Re: [time-nuts] Antennas for Symettricom 2500 Time Source
Note that many Antcom antennas are 2.5 to 24VDC... /Björn Sent from my iPhone > On 9 Jun 2018, at 22:31, Dan Rae wrote: > >> On 6/9/2018 12:05 PM, Bruce Hunter via time-nuts wrote: >> Has anyone stumbled across the 12V antennas for Symmetricom 2500 Time Source >> units. > I have a Symmetricom "Replacement GPS Antenna Kit" P/N 142-614-50 which > consists of "one wide range 5-12 VDC L1 antenna" and 50 feet of Belden 9104 > coax terminated with a BNC. Plus the hardware and stub mast to fix it to a > vent pipe or similar. I don't know what system this antenna was designed for > but the 5-12V spec is interesting. > > Dan - ac6ao > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tektronix FCA3103 ADEV measurement tau setting problem
If this is a badged CNT-91... This is from the current spec. ”The CNT-91 features a frequency range of 0.001Hz to 400 MHz standard with options to 3, 8, 14 and 20 GHz. ” The counter was designed while Pendulum still did R in Stockholm - not very far from Magnus domains. Magnus certainly knows how to do proper ADEV with that counter. — Björn Sent from my iPhone > On 29 May 2018, at 20:58, gandalfg8--- via time-nuts > wrote: > > > I have a Tek FCA3103 300 MHz counter that measures ADEV > > as a built in function. When I bring up the settings > menu for the measurement, it has an entry window for > "tau" (the averaging time, IE "sigma sub y of tau"). > It defaults to 200 ms. I can enter larger values and > ADEV gives reasonably results. However, if I enter > smaller values, even 199 ms, I don't get any error > on the display, but I get clearly erroneous > results for ADEV. I read the manual and cannot find > anything to the effect that the instrument doesn't work > for less than 200 ms. > > BTW, I asked Tek "customer no support" about it and > they were clueless. > --- > > > > Hi Rick, > > > The Tek FCA3100 is a rebadged Pendulum CNT91 and Pendulum became part of > Spectracom. > Unless I'm missing something, the FCA3103 is the FCA3100 with 3GHz input C > fitted. > > > I've also found that Tektronix tech support seemed to know very little about > these but, in the past anyway, found Spectracom in the UK to be very helpful. > I'm not sure about the current status as Spectracom now seems to redirect to > Pendulum as a separate company again. > > > > Unfortunately, I can't help with your enquiry, and am also somewhat confused, > as I don't recall seeing a settings entry window for "tau" as a settings > option for the built in ADEV function. I take it you do mean the built in > option as in displaying results on the built in screen, or are you also using > some external software? > > > If you are just usin the built in display I'd be interested to hear what > firmware version your FCA3103 is showing in the "About" screen > > > > My FCA3100 is showing the firmware version as 1.28s of 25 Aug 2010, which > seems to match the latest available Tektronix download but I'm wondering now > if there are unlisted updates. > > > > Nigel, GM8PZR > > > > > > > > > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TruePosition GPSDO Holdover Issues
There are sometimes rapidly varying ionospheric conditions in some tropical/equator areas - older generation surveying receivers could loose phase look (cycle slips) due to temporal variation. Spatial variation can break the assumption that two receivers doing “RTK” will not have equal iono delay for each satellite - this would reduce base line lengths that could be achieved. Don’t have a reference at hand, but there are publications about CORS station networks in Brazil discussing these phenomena behind the ION paywall. /Björn >> Neat. Thanks. That raises several questions. >> How high do satellites get if you are at a pole? >> What is the best or worst latitude for timing? >> What is the best/worst latitude for doing a survey? > > > The answer for both timing and survey is that you want to be on the equator > as far > as sat elevation / tracks go. As long as you are “in the tropics” it is just > about as good. > > Bob > > >> >> >> -- >> These are my opinions. I hate spam. >> >> >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] RINEX for Android
Hi Jim, Teqc is not a Windows-only program. There are actually several ARM/Debian compilations. I assume some receiver protocols have been implemented with NDAs attached (hey Trimble...) and that might be one reason not to distribute source code. However if JPL would have a long term need for a specific build - Perhaps Unavco would consider supporting that. https://www.unavco.org/software/data-processing/teqc/teqc.html Teqc does translation (binary to Rinex conversion), editing of rinex and quality control of rinex data. Not sure if that is something you want/need to do at your Beaglebone or what post processing package you intend to use. Some post processing softwares might eat uBlox binary natively - all likely support rinex. — Björn Sent from my iPhone >> On 12 Apr 2018, at 18:51, jimlux <jim...@earthlink.net> wrote: >> >> On 4/12/18 6:57 AM, Ole Petter Rønningen wrote: >> I think teqc.exe can read ubx-files directly >> Ole >>> 12. apr. 2018 kl. 12:46 skrev jimlux <jim...@earthlink.net>: >>> >>> It turns out that some of the newer Android phones support an API which >>> returns raw GNSS data and that can be logged to a file in RINEX format. >>> There's a few apps out there that do this although I've not tried it (my >>> Samsung S6 doesn't have the right hardware). >>> >>> In any case, it might be interesting, if you have one of these devices, to >>> let it log for a while, with the phone in a fixed place, and then post >>> process the data. >>> >>> I ran across this when looking for software to generate RINEX files from >>> data from NEO-7 GPS modules (which I'm still looking for) >>> >>> _ > > > I'm working in a Beaglebone environment - ARM, Debian- so the Windows tools > don't work. Before I go out and write python code to push characters out the > serial port and get the output, I was hoping that someone had done some of > this before.. I can do the conversion from a binary file to RINEX somewhere > else. > > rtklib might do the trick, but might also be overkill. It seems that all I > need to do is send the right strings to the GPS and it will start spitting > out the right binary messages, which I then capture and post process. > (perhaps using rtklib's utility to do binary to RINEX). > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS ANTENNA
Or find an Arra “level set” variable attenuator. 3844 and 3854 models can often be found cheaply, have dc-pass and attenuate at both L1 and L2. /Björn Sent from my iPhone > On 2 Apr 2018, at 03:43, David C. Partridge <david.partri...@perdrix.co.uk> > wrote: > > just use a bias tee to feed in the antenna volts :) > > -Original Message- > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Azelio > Boriani > Sent: 01 April 2018 23:29 > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] GPS ANTENNA > > An unusual attenuator with a DC pass. > >> On Sun, Apr 1, 2018 at 10:21 PM, David C. Partridge >> <david.partri...@perdrix.co.uk> wrote: >> Or use a choke ring survey antenna and an attenuator :) >> >> Dave >> >> -Original Message- >> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob >> kb8tq >> Sent: 01 April 2018 14:43 >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] GPS ANTENNA >> >> Hi >> >> Indeed, it is *very* easy to put to much gain in front of a timing GNSS >> receiver. These beasts are trying to dig out a signal that you can’t even >> see with a spectrum analyzer. >> It’s way to far below the noise floor to detect that way. They optimize >> things pretty tightly to get that done (and to hit a price target ….). Put >> to much gain in front of them and they get unhappy. >> >> Making this even more crazy, the survey industry standard antenna *does* >> have a lot of gain. Survey receivers need way more gain in front of them >> than timing receivers. Put a survey antenna directly on a timing device and >> trouble will likely be the outcome. Equally, a survey instrument probably >> will not be happy with a timing receiver. >> >> Why all this nonsense? As far as I can tell, it goes back to how the very >> early L1 / L2 survey boxes were designed back in the 1980’s and early >> 1990’s. They made a basic decision to put a lot of gain at the antenna. >> Motorola came along with their GPS modules later on. They made a *very* >> different decision about how to distribute the gain. There are very good >> arguments on both sides for why they did it this way. >> The bottom line is still - you need to match things up … >> >> Bob >> >>> On Apr 1, 2018, at 2:36 AM, cfo <xne...@luna.dyndns.dk> wrote: >>> >>> On Sat, 31 Mar 2018 10:58:19 -0500, >>> donandarline-Re5JQEeQqe8AvxtiuMwx3w >>> wrote: >>> >>>> I found a supplier for high quality GPS antennas at a very >>>> reasonable price. PCTEL GPSL1-TMG-SPI-40NCB. >>> >>> *** SNIP *** >>> >>> I had one of those on 25m cable, and it worked fine on a Tbolt , >>> until i got an active antenna splitter that also had some gain. >>> Then i had to replace it w. a 26dB version of same type, else the >>> "Jackson Lite" was loosing sync. >>> >>> What i mean here, is that you can get too much gain too. >>> >>> Btw: Good price. >>> >>> CFO >>> Denmark >>> >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Antenna on Tower.
Hi Thorbjörn, To bad this particula antenna has surrounding buildings (and maybe trees) that mask low elevation satellites. -- Björn > http://www.sp.se/en/index/resources/GNSS/Sidor/default.aspx > Have a look at the best receiving antenna I know about. > > The tower must have cooling tubes coiled around it because of the sun > heating one side will make it bend away from the sun, and turn this way > all day. > The cable and doom is also temperature controlled. > > Best Regards > > Thorbjørn W. Pedersen > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies
> So while I'm eager to see Donald's results, I question their merit. The 5061 standards already have a very convenient Cs-Off switch right on the front panel. It is there so you get the pure 10811 performance when you need it. Use it. In fact there's lots of people run their precious 5061 in > Cs-Off mode 23.9 hours a day and just turn on the Cs once a day, or once a > week, to re-cal the oscillator. It's not there just to conserve cesium; you also get full 10811 short-term performance. Note also some 5061 have a > short/long time-constant switch which also helps you tailor the ADEV you want out of the instrument. > /tvb Very nice design by HP. For the same era design, the OSA (telecom) module made other choices. When turning off CS, they turn off power to the output module and the efc tuning circuit. So even if there is a nice and warm BVA inside - without burning CS - the standard output is not working and also its off any manual tuning. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Sinlge ADC multi-band receiver
Hi Bob, > It is a bit unclear what the third > band would add other than a "cool factor" Even quicker RTK convergence. http://www.navipedia.net/index.php/Carrier_phase_ambiguity_fixing_with_three_frequencies -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TU30 jump second
Hi Bo, Are you getting data in binary format [1] or NMEA? The NMEA mode for some Jupiter receivers are known to behave badly in NMEA-mode. The delay would go from 1:ish to 2:ish seconds depending on signal processing load. -- Björn [1] Navman/Jupiter/Conexant/Zodiac/Rockwell binary... http://aprs.gids.nl/gpskit/documents/rockwell/iospec_w708.pdf > Hi List > > Like many of you I also use a Navman Jupiter TU30 in a GPSDO. Besides the > 10 kHz used for the PLL I also have a display showing time. But since a > couple of years, Jan 15?, the time sometimes jumps -1 s and and then later > returns by jumping +1 s Please see an example of the latter below: > > PC-time Diff. GPS-time Diff > ... > 011606.005 0.992 011604 1 > 011607.013 1.008 011605 1 > 011608.005 0.992 011607 2 <--- The issue > 011609.013 1.008 011608 1 > 011610.004 0.991 011609 1 > ... > > I don't experience the same with a ublox GPS. I don't think I saw this > more than two years ago and wonder if the GPS satellites send some > correction data that the rather old TU30 misinterpret? > > Any clues? > > Thanks in advance > Bo > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Manual for Ashtech Ranger Z-12?
Here is also somewhere to look. ftp://ftp.ashtech.com/OEM_Sensor_ADU/Legacy%20products/Z12/ -- Björn > Hi Brooke, > > There is a 16.5 Mbyte manual for the desktop model on: > > http://ashgps.com/mirror/master/Z12-Type%20Receivers/Manuals/z12.pdf > > ...don't know how different the portable "Ranger" model is. > > Peter > > > > On 8 February 2017 at 19:00, Brooke Clarke <bro...@pacific.net> wrote: > >> Hi: >> >> I just got an Ashtech Ranger Z12 and am looking for a manual. >> It appears to be a field portable version of the rack mount Z12. >> >> Brooke Clarke >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wifi with time sync
Hi Bob, Below are some efforts to reduce buffering in both routers and non router network stacks including wifi. They are focusing on reducing latency - maybe some is relevant for you. https://www.bufferbloat.net/projects/make-wifi-fast/wiki/ https://wiki.openwrt.org/doc/howto/sqm https://www.bufferbloat.net/projects/bloat/wiki/Windows_Tips/ -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Survey plot as art.
Hi Gary, >> >> My gut reaction is that "coupling" between the two antennas may >> >> have some effect on some of the variation. >> >> For high accuracy applications, I have been given the advice to keep >> GPS antenna separation much higher. 1 meter separation was suggested. > > Clearly the Adafruit is not high accuracy. I have played with some > short baseline DGPS (cm level data) and not found any issue with antenna > separation. Good for you! Others have found issues. >> For comparing GPS receiver behavior its a cleaner setup to use a GPS >> signal splitter (or basic RF splitter with suitable DC-blocks). > > Care to recommend any that have SMA connectors? I have found that > a 3dB difference in antenna can degrade my data quality, it would be > interesting to see how the 3dB loss of the splitter affects thins. The ZAPD-2DC+ from Minicircuits are good value for money, if 2 ports are enough. The Colorado based "GPS Source" and "GPS Networking" both provide quality products. They have versions with SMA, but also TNC or N. Splitters build for GPS use can be passive, but they are often amplified. They will also pass power up to the lna in the antenna. -- Björn http://194.75.38.69/pdfs/ZAPD-2DC+.pdf https://www.gpsnetworking.com/store https://www.gpssource.com/products/s18s-1x8-slimline-gps-splitter ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Survey plot as art.
Hi Gary, > Yo Artek! > > On Sun, 8 Jan 2017 17:18:06 -0500 > Artek Manuals <manu...@artekmanuals.com> wrote: > >> Only 1" ? (1" center to center or edge to edge spacing?) > > One inch edge to edge. > >> My gut reaction is that "coupling" between the two antennas may have >> some effect on some of the variation. For high accuracy applications, I have been given the advice to keep GPS antenna separation much higher. 1 meter separation was suggested. For comparing GPS receiver behavior its a cleaner setup to use a GPS signal splitter (or basic RF splitter with suitable DC-blocks). -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TrueTime/Symmetricon XL-AK date reset failure
Hi again Joe, Yesterday was 2 Jan. Which was GPS week:day 1930:2. Walk back 1024 weeks and we are in 906:2. Monday in GPS week 906 was May 19th 1997. And that was also the 139th day in 1997. And I think we can confirm the cause of your problem. How to fix it... the GPS receiver module beeing 20+ years old is unlikely to have a firmware update. But try to identify the model and maybe there is a more modern receiver module that works in your box. Another option could be modifying the XL-AK box firmware to add 1024 weeks to the date. The good thing is that its only the date that is computed wrog. Position and time-of-day, 1pps etc are all working as good as before. -- Björn > On 1/1/2016, I noticed that the day > counter display did not automatically reset to zero, and start over. The > day > counter display continued increasing incrementally, until 139 days ago, it > finally reset itself to zero and started incrementally increasing again > from > [day] 1. Which means that the day-of-the-year counter function currently > reads "139," when it should read "2." The time display has always remained > accurate. I had hoped the day counter issue would resolve itself at > midnight > on 1/1/2017; but nothing changed. > > > > I know that the TrueTime/Symmetricon XL-AK and XL-DC GPS receivers are > popular, and now that I have discovered this forum; I would like to > solicit > feedback as to what the root of the problem is and how to remedy it, from > anyone on the forum having personal experience with this line of GPS > receivers. Ideas??? > > > > Thanks de Joe-W6VI > > > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO - probably a stupid question.
Some (all?) Novatel receivers have an option to sync their internal TCXO or let it freewheel. -- Björn > The stability of the typical GPS receiver oscillator is usually inadequate > to be useful as a GPSDO. An OCXO (as in the Trimble Thunderbolt for > example) or equivalent is usually required. One can't usually just add a > varicap to adjust the frequency of a packaged oscillator. If an external > crystal is used the varicap should be placed in series with the crystal. > However to do this reliably one needs to know the crystal parameters and > those of the oscillator circuit. If you need to adjust the frequency both > up and down (due to crystal parmeter tolerances) then an inductor in > series with the crystal and varicap will also be required. > Bruce > > > On Wednesday, 17 August 2016 7:05 PM, Peter Reilley > <preilley_...@comcast.net> wrote: > > > As a neophyte, I was wondering: rather that trying to discipline an > external > oscillator to create a GPSDO and produce a precise 10 MHz why not > discipline the oscillator > of the GPS receiver itself? This could be done with a varactor diode > across crystal of the > receiver's oscillator. Of course there are the same problems with > trying to servo this > oscillator as there are trying to servo an external oscillator but there > are fewer parts. > > Being a beginner I assume that I am missing something, but what? > > Thanks, > Pete. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS antenna selection
>> The real question is how much of a sky view you get. > >> Ideally you would like a clear view of the sky from >> about NE clear around to NW (270 degrees). > > That would opt for the balcony, as it faces north > and extends the slanted roof, so basically clear > view from NE to NW down to the horizon. > Take a look at (yes M$ Silverlight is needed...:( ) http://www.gnssplanningonline.com/ On "Settings" enter 1) your position (lat, lon, h) - or chose approx position from map. 2) change "cutoff" to 0 deg 3) change "Time span" to max (24h). On "Satellite library" 1) Disable Glonass, Galileo, BeiDou and QZSS (only GPS remain selected) Then view "Sky Plot". This is an illustration where the satellites can be seen by your antenna, with no blocking from house, trees, mountains etc. The blue outer circle represents the horizon, north up, etc. Circle center is straigt up into the sky. The fainter grey circles shows 30 and 60 deg elevation from the horizon. - Moving the time-ruler (lower-right corner) will show the satellites move over the selected position. - While moving the time-ruler around, notice that there is a circle from north horizon:ish and down (with a latitude of ca N45deg, where there are never any satellites. - Where this circle is depends on your latitude. (check N90deg -north pole and N0deg (equator) to get a feel of how the priority directions(azimuth)/elevations are. You can model your specific obstruction environment at different possible antenna sites with "Settings" -> "Obstructions". What is an obstruction? it depends, but first order approx is that anything that blocks your view will count. What kind of GPS-receivers will you use? Old receivers (10+years) will need better installations/locations. Modern high sensitivity receivers will work decently within many houses. For long cable runs, older receiver will be more picky, etc. Good luck! -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Q/noise of Earth as an oscillator
I'am not sure how the big ring lasers have progressed over the past years. It seems the big New Zeeland earthquake messed up the nice ring lasers over there. http://www.fs.wettzell.de/LKREISEL/G/LaserGyros.html http://www.phys.canterbury.ac.nz/ringlaser/about_us.shtml -- Björn > I believe a phase noise plot deep into the uHz or lower would apply to the > rotation rate of the earth. > > On Saturday, 23 July 2016, Hal Murray <hmur...@megapathdsl.net> wrote: > >> >> t...@leapsecond.com said: >> > Earth is a very noisy, wandering, drifting, >> incredibly-expensive-to-measure, >> > low-precision (though high-Q) clock. >> >> What is the Q of the Earth? It might be on one of your web pages, but I >> don't remember seeing it. Google found a few mentions, but I didn't >> find a >> number. >> >> I did find an interesting list of damping mechanisms in a geology book. >> Geology-nuts are as nutty as time-nuts. Many were discussing damping of >> seismic waves rather than rotation. >> >> I've seen mention that the rotation rate of the Earth changed by a few >> microseconds per day as a result of the 2011 earthquake in Japan. Does >> that >> show up in any data? Your recent graph doesn't go back that far and >> it's >> got >> a full scale of 2000 microseconds so a few is going to be hard to see. >> >> >> >> -- >> These are my opinions. I hate spam. >> >> >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com <javascript:;> >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP5065A environmental sensitivities
>>> I got a slope of 3.86E-14/hPa frequency difference versus pressure. > > Did you also control for temperature ? > > Air pressure, in particular at high relative humidities changes the > thermal properties of air so there is bound to be some cross coupling > were temperature sensitivities appear as pressure sensitivity. What are time-nuts using for monitoring the environment? I have been playing a little with the Bosch BME280 - doing air pressure, temp and relative humidity in a small form factor. Easy to interface to Raspberry Pi or Arduino. https://www.bosch-sensortec.com/bst/products/all_products/bme280 https://github.com/adafruit/Adafruit_Python_BME280 http://www.satsignal.eu/raspberry-pi/monitoring.html#BME280 -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Trimble SMT 360
Why would the receiver swap between two solutions. One measurement is typically used to compute the time delta between the glonass and gps time. -- Björn Originalmeddelande Från: Bob Camp <kb...@n1k.org> Datum:2016-04-20 05:26 (GMT+07:00) Till: Discussion of precise time and frequency measurement <time-nuts@febo.com> Rubrik: Re: [time-nuts] Trimble SMT 360 Hi Actually there is one other possibility: If you have more than one “system” enabled *and* it’s doing “all in view” *and* it’s applying that to the timing *and* the population in view changes significantly … (whew !) As the solution pops between GPS and Glonass, you will get a time shift. Since it’s a “which one is right?” sort of thing … Trimble probably does not want to get into the debate. They would love to sell stuff to everybody. Bob > On Apr 19, 2016, at 3:32 PM, Logan Cummings <logan.cummi...@gmail.com> wrote: > > Hi Michael, Bob, > > I had been very curious about this myself - the new ICM SMT 360 > modules at first glance seem like a great deal - < $50 and 10MHz TCXO > disciplining built right in. > > I came across this paper which compares the older (GPS-only) ICM SMT > to a LEA-6T - the Trimble fares poorly in their testing. The graphs don't > show an issue quite like yours Michael, so I'd be curious about the line of > questioning Bob brings up, how many satellites are being used by the > receiver - say in GPS-only mode? > > http://www.imeko.org/publications/tc10-2013/IMEKO-TC10-2013-028.pdf > >Does anyone else have comparative experience with the new SMT modules > from Trimble? RES or ICM? > > Thanks, > -Logan > > On Tue, Apr 19, 2016 at 4:01 AM, Bob Camp <kb...@n1k.org> wrote: > >> Hi >> >> The two plots shown appear to be identical. If they are actually two >> different >> runs, the problem repeats very closely. >> >> If the GPS is not in position hold *and* the antenna is less than ideal - >> That’s >> the sort of thing you may see. Essentially it’s got two locations it >> “thinks” are >> correct. Another possibility is a position hold situation with a very low >> satellite count. >> As a single observed satellite goes in and out of multi path, the solution >> goes all over the place. >> Again, you need a challenged antenna for this to happen. Pretty much all >> of this >> would be apparent from the normal messages out of the part. >> >> Bob >> >> >> >>> On Apr 18, 2016, at 10:13 PM, Michael Wouters <michaeljwout...@gmail.com> >> wrote: >>> >>> Does anyone have experience with the Trimble SMT 360 ? >>> >>> I bought some of these four or five months after they were released. >> During >>> testing, the 1 pps output evidenced a problem, as shown in the attached >>> plot (the 1 pps is being measured against a Cs beam standard), which is >>> not sawtooth-corrected. While there are longish periods of nominal >>> operation, the receiver seems to hop between two solutions. This >> behaviour >>> is well out of specification. >>> >>> When I contacted Trimble support, they said that the firmware in the >>> receivers was very early, and replaced the receivers. However, the >> problem >>> was still evident with the new firmware. Trimble did not respond to >> further >>> emails. >>> >>> I tried many things to isolate the problem, including restricting the >>> receiver to GPS-only but I was unable to make an improvement. >>> >>> I would like to know if anyone else is operating an SMT 360 and if they >>> have seen any similar behaviour. >>> >>> Cheers[image: Inline image 2] >>> Michael[image: Inline image 1] >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Precise Time transfer and relative position over a short baseline
Hi Bruce, For such short baselines single frequency GNSS should be able to keep fixed integer solutions. Not sure how much money thas is going to save, since you might need timing specific geodetic receivers to get external 10MHz input. Did you consider implementing time transfer using time reversal using say a sdr tranciever (usrp or other) where your clock is driving the radio. As done on HF by Yen & Sengupta at last PTTI. https://www.ion.org/ptti/abstracts.cfm?paperID=3373 -- Björn Originalmeddelande Från: Bruce Griffiths <bruce.griffi...@xtra.co.nz> Datum:2016-04-11 12:00 (GMT+07:00) Till: Discussion of Precise Time and Frequency Measurement <time-nuts@febo.com> Rubrik: [time-nuts] Precise Time transfer and relative position over a short baseline There is a proposal to use multiple light bucket style optical telescopes to do Intensity stellar Interferometry over short baselines (up to perhaps 1km or so) by using independent clocks to time tag photon arrivals. store the time tags and process the data off line. Depending on the time tag resolution there is a need to measure the time differences between the independent clocks to an accuracy in the 1ns to 100ps range. Is there a better way of doing this other than using geodetic grade GPS receivers capable of GPS carrier phase measurements?Since the local clock flywheel oscillators will need to not deviate by more than 100ps or so over the several minutes required to perform the carrier phase averaging what sort of clock will be suitable apart from a good rubidium standard with a cleanup oscillator? NB Running fibres or coax between the telescopes isnt an option. The relative positions of the telescopes has to be known to within a cm or so for this to work. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LEA-M8T
For navigation more measurements have always been prefered - that is use as many GNSS systems as all your receicers support. That should be true also for common view timing. -- Björn Originalmeddelande Från: Bob Camp <kb...@n1k.org> Datum:2016-04-07 18:41 (GMT+07:00) Till: Bob Stewart <b...@evoria.net>, Discussion of precise time and frequency measurement <time-nuts@febo.com> Rubrik: Re: [time-nuts] LEA-M8T Hi Indeed, if you have not turned off the other systems for timing, you will have issues. Even for precision navigation, you need to turn them off. Until the European system goes up, there will not ba a coordinated approach between any two of the systems. Right now they each make their own assumptions and their own definitions. If you are driving a car down the road, that’s not a big deal. If you are trying to do TimeNuts stuff … A one meter delta is a big deal for timing. A “few” nanoseconds (say >10) is also a big deal. Bob > On Apr 6, 2016, at 9:39 PM, Bob Stewart <b...@evoria.net> wrote: > > Hi Logan, > > I seem to remember Bob Camp mentioning that you can't have multiple satellite > sources in the mix, because the other satellites are inferior to the GPS sats > in timing. Maybe Bob or someone could address this. I would love to > discover that I've set something wrong in all the many, many data structures. > > Bob > > > > On Wed, 4/6/16, Logan Cummings <logan.cummi...@gmail.com> wrote: > > Subject: Re: [time-nuts] LEA-M8T > To: "Bob Stewart" <b...@evoria.net>, "Discussion of precise time and > frequency measurement" <time-nuts@febo.com> > Date: Wednesday, April 6, 2016, 8:18 PM > > Hi > Bob, > Can't speak to > jitter accuracy but the M8 series is definitely not the same > receiver in the 6 series. As you probably know, M8 > introduced multi-GNSS support so in addition to GPS you have > Beidou and Glonass satellites. > At work we've had some gnashing of > teeth about the wider filter passband requirements for > multi-GNSS support since we're operating in a noisy > environment, but I have nothing further on degraded > performance when using only GPS. > Would be interesting to let > it have all the constellations and see what > happens. > -Logan > On Wed, Apr 6, 2016 at > 10:04 AM, Bob Stewart <b...@evoria.net> > wrote: > I > recently bought a number of LEA-M8T receivers and I have to > say that I am unimpressed, so far. They don't survey > to the same reported accuracy as the LEA-6T in the same > amount of time. They certainly aren't better in the > jitter after sawtooth correction. So, have I managed to > overlook some new field, or are they just not the same > receiver as the 6T? I did shut all sats off except GPS > sats. > > > > Bob - AE6RV > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Conditioning Rubidium Oscillators
I have seen no national timelab using cheap L1 stuff for high quality time transfer. Btw... its been discussed here multiple times over the years. Ashtech Z12-T and fast forward over the past 20years. Look at a geodetic receiver with optional external freq input. They are available from most of the big names. A very interesting question why someone spend $$$ on masers and not a much smaller amount on good antennas and multi frequency gnss receivers. Btw the local vlbi-site have lots of high end gnss rx. -- Björn Originalmeddelande Från: Hal Murray <hmur...@megapathdsl.net> Datum:2016-03-15 04:18 (GMT+01:00) Till: Discussion of precise time and frequency measurement <time-nuts@febo.com> Kopia: hmur...@megapathdsl.net Rubrik: Re: [time-nuts] Conditioning Rubidium Oscillators elfchief-timen...@lupine.org said: > Are there currently any decent (intended (or at least usable) for > timekeeping) GPSs that support using L2/L5 for this purpose? Google is > turning up lots of nothing, for me... I don't know of any. I'm somewhat sure that they don't exist or maybe they are hidden in the military sector. Tom Clark and Rick Hambly work on timing for VLBI. They run a yearly workshop on timing. Their slides are available on the web. They use low cost L1 gear. I'm sure they would use something better if it were available commercially. They are starting with Hydrogen Masers so cost cutting on the GPS receiver would not be a problem. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] BG7TBL GPS Disciplined Source
Originalmeddelande Från: Gedas <w8...@mchsi.com> Datum:2016-03-14 19:52 (GMT+01:00) Till: Discussion of precise time and frequency measurement <time-nuts@febo.com> Rubrik: Re: [time-nuts] BG7TBL GPS Disciplined Source Who would have guessed a Russian OCXO. And, I guess the U-Blox is not one of the better GPS units based on what Paul mentioned. But I think there is software out there that will let me at least monitor what my unit is doing and how many birds it is receiving data from. Ublox makes excellent receivers. The monitoring software is fine. https://www.u-blox.com/en/product/u-center-windows But they dont talk (old) scpi. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Outage
"The product will not report the correct extended GPS week number after the Feb,13th 2016. After the rollover to week #860, the thunderbolt will not make position for 2 hours, because the Ephemeris data on the GPS receiver being consider incorrect. The module will work fine after this 2 hours." Have the Motorola Oncore/Navman/Jupiter receivers also been checked for this condition? Strange that at least 3 independant firmware trees/development teams should chose the same magic wk860. I guess that someone with both affected non-trimble receivers and a gps rf simulator would need to spend some time on this. -- Björn Originalmeddelande Från: Martin Burnicki <martin.burni...@burnicki.net> Datum:2016-02-26 09:32 (GMT+01:00) Till: time-nuts@febo.com Rubrik: Re: [time-nuts] GPS Outage Mark Sims wrote: >> When is some organization going to explain what happened in February for >> almost two hours starting at 00:16 GMT? That subject has gone silent. Rob, >> NC0B > I heard back from NAVCEN. They said it was a Trimble issue and that Trimble > would contact me (they didn't). But that does not jive with reports of > failures in Motorola, Navman, etc receivers. I think we need to distinguish here. The January 26 issue was due to faulty data sent by the satellites, which caused GPS receivers to apply a wrong UTC correction which caused the UTC time to be off by 13.7 us. As explained by Luc Gaudin from http://naelcom.com (who obviously sell Trimble GPS receivers) the February 13 issue was indeed just a Trimble firmware problem. See: https://www.febo.com/pipermail/time-nuts/2016-February/096042.html https://www.febo.com/pipermail/time-nuts/2016-February/096050.html Martin ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP Reliability
Hi, Spent the flight back from PTTI next to a HP, then Agilent medical guy. Aparently the medical stuff did not go into Keysight, they remain Agilent. -- Björn > Hi, > It is rather depressing to me to hear RK and others remark about the > unreliability of HP test equipment. > There is one area where they had outstanding equipment. > I was involved with repairing HP medical equipment for 25 years and it was > awesome stuff. This was the same info I got from other BMET's at many > different hospitals. > The TCO was low as the equipment ran and ran, a lot of it 24/7. I'm > talking about a 10 year period. > Usually our equipment was only replaced by newer technology systems. > Too bad it didn't apply to test equipment as well. > Regards, > Perrier > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] looking for rakable GPSDO
Meinberg, Microsemi (former Symmetricom), Brandywine, Arbiter, Spectracom, Zyfer -- Björn Originalmeddelande Från: Stéphane Rey <steph@wanadoo.fr> Datum:2015-10-19 16:10 (GMT+01:00) Till: time-nuts@febo.com Rubrik: [time-nuts] looking for rakable GPSDO Hello, I'm looking for a 10 MHz output GPSDO with external antenna which would be rackable. Symmetricon doesn't seem to propose some neither Keysight. Found some stuff in Oscilloquartz. Any other brand to suggest ? Thanks & cheers Stephane ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Rohde & Schwarz GPSDO
You might get some oscillator information by looking at the Meinberg site. https://www.meinbergglobal.com/english/specs/gpsopt.htm Is this a badged Meinberg unit or a R built on the Meinberg GPScard? -- Björn Originalmeddelande Från: Tom Knox <act...@hotmail.com> Datum:2015-10-08 05:21 (GMT+01:00) Till: Time-Nuts <time-nuts@febo.com> Rubrik: Re: [time-nuts] Rohde & Schwarz GPSDO What is interesting is I spent a little time on the Manufactures Web Site and could find no AD or PN specs. So even if you can find the down converter antenna, you have no idea how well it will perform. I imagine it has a something like an Oscilloquartz 8663. No doubt as with almost all RS products it will be very high build quality. Cheers; Thomas Knox > From: rbenw...@verizon.net > To: time-nuts@febo.com > Date: Wed, 7 Oct 2015 22:41:11 -0400 > Subject: Re: [time-nuts] Rohde & Schwarz GPSDO > > That's why you can run 300meters of RG-58! This is the "missing" > antenna/converter unit. > > https://www.meinbergglobal.com/english/products/gps-antenna-converter.htm > > Here is one, this time with the antenna: > http://www.ebay.com/itm/Meinberg-ED170MP-GPS-Satellite-Disciplined-Atomic-Cl > ock-10MHz-Oscillator-Antenna-/281560964740?hash=item418e575e84 > > Bob > > >>> -Original Message- > >>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Arthur > >>> Dent > >>> Sent: Wednesday, October 07, 2015 7:46 AM > >>> To: time-nuts@febo.com > >>> Subject: [time-nuts] Rohde & Schwarz GPSDO > >>> > >>> I believe that like a lot of the Meinberg receivers that this uses a > down > >>> converter to give an IF frequency of > >>> 35.4 MHz. If you don't have the converter that apparently isn't included > with > >>> the receiver you have a $300 paperweight. > >>> You might want to check with the seller before bidding. > >>> > >>> -Arthur > >>> ___ > >>> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to > >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >>> and follow the instructions there. > >>> - > >>> No virus found in this message. > >>> Checked by AVG - www.avg.com > >>> Version: 2015.0.6140 / Virus Database: 4435/10749 - Release Date: > >>> 10/03/15 > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS outage? 19:00-2100 UTC Tue
What sort of gear would I need to detect a local jammer? A GPS receiver where you can get AGC data, to see if the power in the GPS band increased - or a SDR-radio, like the SDR-RTL at sub $20 or a commercial GPS jamming detector. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Has my TBolt gone south ?
A nearby thunderstorm could have taken out the preamp in the antenna. 73 Bill Beam NL7F Carefully powering the antenna from a separate supply and then measuring the current - is one way of checking that the LNA still works. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wtd: WWVB info
Don't know about DE to USA shipping, but the bare modules are available for around or sub 10€ depending on quantity. http://www.hkw-shop.de/Empfangstechnik-AM/Empfangs-Module/ /Björn div Originalmeddelande /divdivFrån: Donald donvuko...@gmail.com /divdivDatum:2015-08-07 22:43 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] wtd: WWVB info /divdiv /divOn 8/7/2015 8:13 AM, Brian Inglis wrote: Given a $10 60kHz receiver, This is the problem. I can not find $10 receivers any more. I can find $15-$20 receivers (from the UK), add shipping and it minimum $20+. Even the older chips still work with the new format, its just finding them, cheaply. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LORAN-C reception in the UK
I think Denmark will also cease operation of their one station in line with Norway and France. What is the plan for Germany and the UK - not enough stations for a full chain? New controlling station - since Lessay leaves? -- Björn div Originalmeddelande /divdivFrån: ken hartman k...@hartmans.org /divdivDatum:2015-07-10 22:46 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] LORAN-C reception in the UK /divdiv /divfrom: http://gpsworld.com/eloran-progresses-toward-gps-back-up-role-in-u-s-europe/ “Both Norway and France have declared an intention to cease Loran transmissions at the end of 2015. Moreover, France intends to dismantle its Loran infrastructure in 2016. Arrangements for the commercial operation of the infrastructure are being investigated, but this depends on some form of regional agreement. The European Union appears to have no policy for resilient PNT, the European Radio Navigation Plan having twice been drafted but never published. The view seems to bee that the introduction of Galileo will achieve resilient PNT, which it will not.” On Fri, Jul 10, 2015 at 7:14 AM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: How good/bad would a LORAN-C frequency reference such as the Stanford Research FS700 work in the UK? I live about 60 km to the east of central London. Is there any future for LORAN-C in the UK? I am looking for a frequency reference that is not GPS - I already have a GPS frequency reference but would like to compare it with something independent of GPS. Just having two GPS receivers provides two signals which are probably highly correlated. Dave. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Loran and SRS FS700 in the UK
Are not Excelis and UrsaNav doing test transmissions again? div Originalmeddelande /divdivFrån: paul swed paulsw...@gmail.com /divdivDatum:2015-07-11 17:23 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] Loran and SRS FS700 in the UK /divdiv /divNigel I have a FS700 and would like a copy of the software. I enjoyed the use of LORAN C when it existed and even in some of the test runs. The runs have been pretty quite or I have missed them. But LORAN C made a really nice alternate to GPS and I tended to use it as the absolute. I do here LORAN from Europe in the winter at night and can occasionally lock the systems here and I am some 2000 miles east. If became a drop motivated I could build a far better antenna for the job. Though there never seems to be any detail of large loran c antennas its always the whip and preamp for boats. Regards Paul WB8TSL On Sat, Jul 11, 2015 at 1:02 AM, Dr. David Kirkby (Kirkby Microwave Ltd) drkir...@kirkbymicrowave.co.uk wrote: On 11 Jul 2015 03:28, GandalfG8--- via time-nuts time-nuts@febo.com wrote: This is a reply to the topic Loran-C reception in the UK with specific emphasis on the Stanford Research FS700. Points to note. All three of my units seem to have the Option 01 oscillator fitted, although only one states this on the option label, so perhaps this became standard with later production. I don't know and wouldn't take it for granted but thought it worth a mention. The fitted oscillator in each unit is an identically specified SRS SC10. Mine are off air right now as I swap about stuff in the timing rack, and haven't really been run for much more than initial tests, albeit for quite long periods. My general impression so far is that the reported frequency offset might be a bit optimistic, this is compared with Thunderbolt GPSDOs, but I need to do more work on this. Useful to know, but of course it could be the errors are on the Thunderbolts! The problem with having multiple GPS units is that they are not exactly independent of each other. The latest FS700 firmware I have seen is version 1.20. I can make the 1.20 firmware available if anyone would like a copy. I might take you up on that if I get an FS700. FS700s have become available on Ebay at very good prices since the USA Loran-C chain was closed down, that's why I have three:-), but it needs to be noted that these are mainly from recycling outfits, what we might once have referred to as scrap yards in the UK, and usually untested and with no warranty. On average mine have cost me about 200GBP each, including shipping and tax, but beware of some sellers still asking anything up to 1000USD before shipping and import tax. I have never seen them at anything like the price you see. About the cheapest I have seen is $600. I did notice one or two on eBay that are rusty, which struck me as odd. That small mains transformer runs really hot, not too surprising perhaps, and I've seen at least one online photo showing two larger transformers mounted in the space towards the front of the unit. One or two probably depends on what's to hand but I would suggest a very worthwhile change. Mains voltage here is generally over 245 volts, so a bit on the high side, but I do believe that transformer is underrated. Are there multiple secondries? If not getting a replacement should not be hard but otherwise it could be tricky. I know someone who run his whole house on an autotransformer because his mains voltage was too high. Small point, but a nuisance, there's no backlighting on the LCD display. Overall impression, an excellent unit with programmable output frequency and built in phasemeter, and I can't wait to get mine back on the air:-) If I could get one for £200 imported into the UK I would definitely get one. I thought I would need to pay considerably more than that. I have seen some in Hong Kong and China. I don't know if the system ever worked there, but if not then Regards Nigel GM8PZR Cheers Nigel. Dave G8WRB. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LORAN-C reception in the UK
Did you check the jamming radius? div Originalmeddelande /divdivFrån: Magnus Danielson mag...@rubidium.dyndns.org /divdivDatum:2015-07-11 18:00 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivKopia: mag...@rubidium.se /divdivRubrik: Re: [time-nuts] LORAN-C reception in the UK /divdiv /divHi, On 07/11/2015 03:18 PM, Poul-Henning Kamp wrote: In message CAPbEEQJxn+R5AvCenfyXjFU=WOjFbYxZd2EC_hX=c6muyev...@mail.gmail.com , ken hartman writes: the European Radio Navigation Plan having twice been drafted but never published. The view seems to bee that the introduction of Galileo will achieve resilient PNT, which it will not.” The reason the ERNP wasn't published, was that it concluded that 40% of *all* benefits came from Loran-C, at a yearly cost only a fraction of a single Galileo launch vehicle. Someone should have dreamed up the aggregate robustness of eLoran, GALILEO and EGNOS. LORAN-C and eLORAN would be an interesting combination to GPS and GALILEO. Sweden essentially had it's own set of LORAN/Chayka transmitters, with a ever evolving jamming/spoofing ability. RT-02 Fredriksson was the system name, often just referred to as Fredriksson. http://www.antus.org/RT02.html http://www.fht.nu/fv_bilder_radio_rasandare_rt_02.html http://www.fht.nu/Dokument/Flygvapnet/flyg_publ_rapport_rt_02.pdf So much for jamming-resistant. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] beaglebones, time, web services
If looking at using the bbb for driving steppers. http://blog.machinekit.io/p/hardware-capes.html?m=1 /Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] End of the World, or beginning of a new one?
Yes the Tymserve and other similar DATUM / Symmetricom products which use the Trimble ACE board will fail again in 2016. This is due to the way the GPS epoch is calculated inside the 2100 : the DATUM engineers estimated the future leap second insertions to determine GPS epochs, which was not a so good idea... That was Trimble engineers... anyone with the actual algorithm they used? /Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Terrestrial Tides and Land Movement
Bob, Tom says 'almost'. In a static location you can improve your timing results by establishing your antenna position as good as possible. It will work almost as good without a survey. In a moving scenario you can of cause not do a survey. But try finding another way to do time transfer with better performance. Btw... pure position averaging over many hours does not seem so optimal by todays standards. Some ppp-version even on L1-only should be more effacient. -- Björn div Originalmeddelande /divdivFrån: Bob Stewart b...@evoria.net /divdivDatum:2015-05-25 20:09 (GMT+01:00) /divdivTill: Discussion of Precise Time and Frequency Measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] Terrestrial Tides and Land Movement /divdiv /divTom said: The nice thing about GPS, unlike other time transfer methods, is that can handle the case of a moving antenna. As the antenna moves so does the time. This is why GPS timing receivers work (almost as well) on top of your car as on top of your house. I don't get that. What's the purpose of doing a survey when you move your antenna if this the case? Bob From: Tom Van Baak t...@leapsecond.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, May 25, 2015 12:29 PM Subject: Re: [time-nuts] Terrestrial Tides and Land Movement Attila, Timing people account for everything that's important. A continental drift of an inch per year acts like a slow phase change over time, which by definition, is a frequency offset. So an inch per year is at most 1/12 * 1e-9 / (365*86400) or 3e-18. For the current precision with which UTC/TAI is calculated this is too small to worry about. The other way to think of the frequency offset is simply the ratio of speed-of-continent vs. speed-of-light. A continent is slow, about 1e-9 m/s and light is fast, 3e8 m/s. This ratio is about 3e-18. Note that an inch-per-year is about a nanometer-per-second. I'm also told fingernails grow about an inch a year. How's that for a rule of thumb (literally). There's a nice (1 inch) 25 mm per year interactive drift map here: http://www.unavco.org/software/visualization/GPS-Velocity-Viewer/GPS-Velocity-Viewer.html The nice thing about GPS, unlike other time transfer methods, is that can handle the case of a moving antenna. As the antenna moves so does the time. This is why GPS timing receivers work (almost as well) on top of your car as on top of your house. Just think of continental drift as a slow moving car. /tvb See also: http://www.iris.edu/hq/files/programs/education_and_outreach/aotm/14/1.GPS_Background.pdf http://www.unavco.org/education/resources/educational-resources/tutorial/how-quickly-are-we-moving-gps-tutorial.pdf - Original Message - From: Attila Kinali att...@kinali.ch I am not sure whether anyone accounts for continental drift in timing applications. I would guess that at least people in VLBI have to. Given that most GNSS high precision time transfer is used rather locally (a couple of 100km) and that few people are running it for more than a couple of months without recalibrating the system, i'd say that the drift rates (which are between 2.5cm(Arctic) and 15cm(Chile) per year) do not induce much error/jitter. Attila Kinali ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 130, Issue 27
Hi Bob, You are confusing the readers here. 1) zero altitude relative the WGS84/GPS ellipsoid are often tens of meters over or below sea level, depending on your location. 2) zero altitude relative to a geoid (EGM96 or something else) is very close to sea level. Then if you think of the ellipsoid as a second order model of the geoid... we can start comfusing people again. -- Björn Hi The gotcha is that the GPS numbers are related to a geoid model and not to sea level. You can indeed find points that are âunderwaterâ based on the geoid, but quite dry in real life (and vice-versa). Bob On May 19, 2015, at 12:26 PM, Demian Martin demianm@gmail.com wrote: I would buy that (Google Maps being off) except that I'm less than 2 miles from the SF bay and -5M would have me underwater. That may well happen but not for a few years at least. Also the Arbiter does match Google maps pretty closely. It doesn't really matter a lot, just a curiosity. Demian Date: Mon, 18 May 2015 18:12:58 -0400 From: Bob Camp kb...@n1k.org To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Thunderbolt Height Error Message-ID: 1ae37b6b-35fd-4c5f-95d6-01316d6c4...@n1k.org Content-Type: text/plain; charset=us-ascii Hi The simple answer is that Google maps may or may not be correct. There are a lot of examples of them being off by 10M or more. That said, my *guess* would be that the Thunderbolt is closer to the truth. Bob On May 18, 2015, at 2:34 AM, Demian Martin demianm@gmail.com wrote: I have 2 GPSDO's. A Thunderbolt and an Arbiter 1083A. The Arbiter is old but it works fine (and has a Wenzel 5 MHz streamline oscillator in it). It has the 1995 firmware issue, and I could get new firmware for it ($$) but I'm not using it as a clock, just a frequency source. I just moved and have re-setup both. They share an antenna. I got both to do a self survey. The Arbiter was really close to what Google maps indicate is my location. The Thunderbolt was about the same except it has me underground. The arbiter has the height as +30M. The Thunderbolt as -6M. What setting do I have wrong in the Thunderbolt? Would it affect the operation as a frequency standard in any way? Demian Martin San Leandro, CA 94577 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt Height Error
Hi Demian, Did you make sure the altitude/height is using the same reference? The GPS system measures relative an ellipsoid approximation of the earth. Sometimes this is used in receiver output messages. To translate this to Mean Sea Level/geoid you need to apply a location dependant correction. The GPS receivers will happily emit both height measures in different messages, its important to understand which is used in the specific messages you are comparing. Have it better explained in the below url: http://www.esri.com/news/arcuser/0703/geoid1of3.html Also not that height accuracy of GNSS is worse than its horizontal accuracy by almost a factor of 2. -- Björn I have 2 GPSDO's. A Thunderbolt and an Arbiter 1083A. The Arbiter is old but it works fine (and has a Wenzel 5 MHz streamline oscillator in it). It has the 1995 firmware issue, and I could get new firmware for it ($$) but I'm not using it as a clock, just a frequency source. I just moved and have re-setup both. They share an antenna. I got both to do a self survey. The Arbiter was really close to what Google maps indicate is my location. The Thunderbolt was about the same except it has me underground. The arbiter has the height as +30M. The Thunderbolt as -6M. What setting do I have wrong in the Thunderbolt? Would it affect the operation as a frequency standard in any way? Demian Martin San Leandro, CA 94577 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 53132A Polish UHS Time Base Option Interesting Ovservation
Zyfer have(had?) some papers on g-compensated oscillators by Fruehof. -- Björn div Originalmeddelande /divdivFrån: D W watsondani...@gmail.com /divdivDatum:2015-05-12 17:49 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] 53132A Polish UHS Time Base Option Interesting Ovservation /divdiv /div And this is where one question leads to another. For an oscillator that is going to be used at very high velocities and accelerations, like in a missile, would it be calibrated somehow under the target G force? Or would you just compensate some other way? Or just not worry about it? Dan On May 12, 2015, at 6:51 AM, Bob Camp kb...@n1k.org wrote: Hi All OCXO’s are sensitive to acceleration. Gravity is one form of acceleration. A sensitivity in the 0.5 to 2 ppb / G is not uncommon. Bob On May 11, 2015, at 9:24 PM, J. L. Trantham jlt...@att.net wrote: I recently obtained a 53132A and added the HP Opt 010 High Stability Time Base option with a 10811 variant OCXO. I left it on for over a week and it, ultimately, seemed to slow down in its drift, with the displayed frequency, as it 'read' my GPSDO, slowly decreasing, suggesting that the Time Base was, slowly, increasing in frequency. I then removed the HP option and installed a Polish UHS Time Base option with a Morion DOCXO. After about 72 hours, it seemed to stabilize. I then 'calibrated' the 53132A by connecting my GPSDO to Channel 1. The displayed frequency was +/- 1 to 2 mHz of 10.000 000 000 MHz for the past week or so, with no drift noticeable. I had 'calibrated' the 53132A with it sitting at about +30 degrees, propped up on its 'handle' in a 'vertical' position. I then had occasion to move the 'handle' under the unit whereby the unit was 'flat', at which point the displayed frequency dropped to 9.999 999 997 MHz, +/- 1 to 2 mHz. The displayed frequency was the same this evening when I came home. When I again 'elevated' the unit by moving the handle to its more 'vertical' position, the displayed frequency moved to 10.000 000 000 MHz +/- 1 to 2 mHz. I'm not sure what this means. It is a 'repeatable' observation. It displayed the lower frequency all day and when I 'elevated' the 53132A this evening, the frequency again went to 10.000 000 000 Mhz. Is this a 'gravity' effect? Is this an issue with the DOCXO? Is this an issue with the 53132A? If I am correct in my calculations, the displayed frequency is +/- 1 to 2 parts in 10E-10 of 10 MHz, assuming my GPSDO is accurate and stable. Otherwise, the GPSDO and 53132A 'drift' is exactly the same. I would appreciate anyone's thoughts regarding this analysis and observation and how to go about 'quantifying' it in a more scientific method, assuming it's worth pursuing. Thanks in advance. Joe ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] lawnmower robots may be the end of VLF timekeeping
http://forum.blitzortung.org/showthread.php?tid=705highlight=lawn+mower Working url. Sorry for the mistake in previous post. -- Björn div Originalmeddelande /divdivFrån: Björn b...@lysator.liu.se /divdivDatum:2015-05-09 20:15 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] lawnmower robots may be the end of VLF timekeeping /divdiv /divThe same has been observed by the lightning listeners at blitzortnung.org -- Björn div Originalmeddelande /divdivFrån: Poul-Henning Kamp p...@phk.freebsd.dk /divdivDatum:2015-05-09 14:15 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: [time-nuts] lawnmower robots may be the end of VLF timekeeping /divdiv /divI spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] lawnmower robots may be the end of VLF timekeeping
The same has been observed by the lightning listeners at blitzortnung.org -- Björn div Originalmeddelande /divdivFrån: Poul-Henning Kamp p...@phk.freebsd.dk /divdivDatum:2015-05-09 14:15 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: [time-nuts] lawnmower robots may be the end of VLF timekeeping /divdiv /divI spent some time capturing some data today. The measurements is from my $20 loop-antenna in the attic, which is something like 8 meters up and 10 meters besides the lawn-mower loop: http://phk.freebsd.dk/time/20150509.html -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Important parameters for a GPS/GNSS antenna
Also consider phase wind up. http://www.navipedia.net/index.php/Carrier_Phase_Wind-up_Effect Sure there are also some papers on rotating antennas. http://www.researchgate.net/profile/Simon_Banville/publication/257945217_Antenna_Rotation_and_Its_Effects_on_Kinematic_Precise_Point_Positioning/links/0deec5266c9c6ac71800.pdf Due to the polarization of GPS signals, carrier-phase measurements made by GPS receivers are affected by the orientation of the antenna. On the other hand, code measurements are not affected by this effect. -- Björn I'm curious whether it would need 360 degree rotation? Would simply cycling about 120 degrees on the end of a short arm be just as good and could be done without a rotary joint? I understand that now the RX is moving but within a small radius would it be unbearable? Or would 300 degrees around the axis be sufficient? From Tom Holmes, N8ZM On May 7, 2015, at 11:49 AM, John Ackermann N8UR j...@febo.com wrote: Just put the GPS antenna, receiver, battery, and a low power RF transmitter modulated by the PPS (wide bandwidth = fast edge time) on the turntable, then use an appropriate receiver to demodulate the PPS and feed it to the rest of the system. Put the RX antenna directly above (or below) the turntable so the path length remains close to constant. Using FM might also remove Doppler effects from the received pulse. On 5/7/2015 11:18 AM, Tom Van Baak wrote: I wonder if anybody ever made a rotating GPS antenna to average out the X-Y phase-center offset ? Of course, this does not really work with a gps antenna, unless you put the whole receiver onto the rotary table. But then you shift the problem onto the PPS output (note: amplitude noise translates into phase noise). Attila, My thought was to put PHK's proposed experiment entirely on the rotating table: antenna, receiver, local Cs standard, laptop, and battery. You could also get interesting data if you slightly offset the antenna from the center. It would make the ultimate GPS Spirograph. (for those of you under 40, http://en.wikipedia.org/wiki/Spirograph will explain) /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Microsemi versus Spetracom
Look also at Brandywine and Meinberg. /Björn div Originalmeddelande /divdivFrån: Andrew Cooper acoo...@keck.hawaii.edu /divdivDatum:2015-05-06 21:58 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: [time-nuts] Microsemi versus Spetracom /divdiv /divSo, yes, our old TS2100's suffered the 1995 bug over the weekend like all of the others in the world. Kludged into working for the moment using 1PPS and two units. I do need to buy a couple replacements, good time is critical around an observatory, looking at a $16K purchase order. We have quoted both the SecureSync from SpectraCom and the S350 from Microsemi, both fully spec'd out with IRIG and IEEE1588. I am not really a time expert, just an everyday electrical engineer. Thrust into the problem three days ago. I have learned a bit reading through the Time Nuts archive... Thanks! Anything I should be aware of with these units. Any opinions on this purchase? Thanks for your advice, Andrew Andrew Cooper Electrical Engineer W. M. Keck Observatory 808-881-3862 mailto:acoo...@keck.hawaii.edu ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] XL-DC was Re: time-nuts Digest, Vol 127, Issue 33
Hi, AT575-142TTW-TNCF-000-RG-41-NM Not all 575 antennas eat the same power. Its the RG in the part number above that specifies 4.2V to 15V DC power for the internal LNA. This is the most common option - but there are others. -- Björn div Originalmeddelande /divdivFrån: Bob Camp kb...@n1k.org /divdivDatum:2015-02-27 20:21 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] XL-DC was Re: time-nuts Digest, Vol 127, Issue 33 /divdiv /divHi One important caution on antennas: The 575 is quite happy with anything from 5 to 18V as a feed voltage and only pulls 35 ma. There are antennas out there that don’t like voltages over 6V. There also are antennas on the market that pull well over 50 ma. If the “original” box sourced 12V to the antenna and triggers as “overload” around 50 ma, the 575 will work great with the box. If you plug a modern timing antenna (= 5V version) into the box the antenna may be damaged and / or the over current may trigger. There also are 3.3 V antennas out there, but they are rarely seen in timing applications (yet). Simply put - the 575 is a great antenna and it will work on a lot of stuff. The problem is not at all with the antenna. It’s with the stuff specified to work with it. You have no way of knowing if it’s a 12V gizmo or a 5V feed. The same issue can come up with downconverter feeds. They often put +12 on the feed to run the downconverter. It’s best to put a DVM on the feed before attaching a nice new $1,500 antenna to it …(or even a $20 one) Bob On Feb 27, 2015, at 1:11 PM, Russell Rezaian r.reza...@earthlink.net wrote: I can confirm there are at least two common varieties of the XL-DC GPS RX board. One uses a normal GPS antenna (no down-converter, provides DC on the antenna line for an amp in the antenna, the typical antenna provided seems to be an AeroAntenna AT575 variety, but I suspect other antennas that are similar should be fine). The specific antenna part I have is: AT575-142TTW-TNCF-000-RG-41-NM It's been a while since I last decoded that part number but it's a very easily re-useable general use GPS antenna with an integrated RF amp. Works over a fairly wide range of DC supply voltages and claims a slightly higher gain than some other standard timing GPS ice cream cones. There are also versions of the GPS module for the XL-DC that use a GPS antenna with an integrated down converter that is actually physically part of the antenna provided. The down converter antenna is normally a single integrated unit. The part numbers I see on one I have handy are 140-614 (TrueTime) or Model 142-6150 on the Symmetricom label. I don't have any details for the voltages or whether there is a reference frequency provided for the down converter style receiver. I have seen some suggestions that they also had a dedicated down converter module that could be used with normal GPS antennas, but I don't have any details on that option. If you have a RX module that needs the converter antenna there should be a clearly visible little label indicating this on the module itself near the antenna connector. If you don't have that label the RX should work with most GPS antenna systems (and also with most antenna splitter systems too). -- Russell Al Wolfe wrote: I have an XL-DC and it has an internal GPS receiver in it. It supplies and monitors 5 volts to a BNC antenna jack for an external amplified GPS antenna. I don't know what the internal GPS engine is but doubt if it is anything special. The manual describes the down converter system as an option. Al, k9si Boy I ran out to mr google and did a search and now I am wondering if some versions of the xl-dc just used a plain old GPS antenna. It sure looks like that could be the case. The manual does say down converter. Maybe it changed over time. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] L1 and L2 frequencies
Brooke, The traditional GPS has C/A and P(Y) on L1 and P(Y) on L2. Most Civilian GPSes only uses C/A. Advanced receivers can also use P(Y) code, since the P-code is known, the hand-off to P code is known and the way that P-code is encrypted into Y-code is known (XOR with another code, called A-code or W-code in different sources). Modern receivers is able to do both code and carrier phase observations on the P(Y) code signals. Read up on semi-codeless tracking, I dont think (pure) codeless is used anymore. http://www.colorado.edu/ASEN/asen6090/ztracking.html https://books.google.se/books?id=-sPXPuOW7ggCpg=PA240lpg=PA240 The military goal of this break-in is not lost, as those receivers still rely on the C/A code and that is easy to jam. Also, the break-in comes at a signal quality loss and the advancement of methods have reduced this loss. The benefit of dual frequency observation is that ionspheric shift can be almost completely taken out of the error budget, adjusting both code and carrier phase observations. Then working on the integer ambiguity you can get carrier phase observations with accurate pseudo-ranges. Carrier-phase observations has a much higher precision to them, so that gives a very high precision and using a good reference network corrections can be adjusted to give good absolute position. If civilian receivers where to implement L2C and L5 which now is becoming common, they would gain quite a bit of precision in a similar fashion. For car navigation, the GPS would know which lane you are in. There ARE civilian receivers doing this, and has been for quite some years. And its not from only a few vendors - all the big ones have it - Trimble, Novatel, Topcon, Javad, Leica, Septentrio and a few more. There are now receivers tracking GPS L1/L2/L2C/L5, Galileo E1/E5A/E5B/AltBoc/E6, GLONASS L1/L2/L3, BeiDou B1/B2/B3, QZSS L1/L2/L5 The price exceeds my home hobby budget, but so does a replacement CS-tube a factory new OCXO based GPSDO and many other things you can sometime find at reasonable cost used/recycled. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] L1 and L2 frequencies
Magnus, If civilian receivers where to implement L2C and L5 which now is becoming common, they would gain quite a bit of precision in a similar fashion. For car navigation, the GPS would know which lane you are in. There ARE civilian receivers doing this, and has been for quite some years. And its not from only a few vendors - all the big ones have it - Trimble, Novatel, Topcon, Javad, Leica, Septentrio and a few more. There are now receivers tracking GPS L1/L2/L2C/L5, Galileo E1/E5A/E5B/AltBoc/E6, GLONASS L1/L2/L3, BeiDou B1/B2/B3, QZSS L1/L2/L5 The price exceeds my home hobby budget, but so does a replacement CS-tube a factory new OCXO based GPSDO and many other things you can sometime find at reasonable cost used/recycled. I naturally meant with a reasonable price-tag, sorry for being sloppy on that detail, and I do know that there is vendors for those signals. If we had dual or triple frequency receivers below 500 USD things would start to be interesting. If high-volume kits would be just twice as expensive, it would be possible to consider for more luxury models. Receiver with 24 universal channels each of GPS L1/L2/L2C/L5 is cheaper than a entry level TCXO-based 19 GPSDO (M300GPS @ Dustin). And about the same price as a modern Loran receiver. What is a reasonable commercial price? But yes, multi frequency GNSS is much more expensive than the Oncore, Ublox traditionally used in a GPSDO. Is the performance gain worth the cost? Certainly not for all but a few. On the oscillator side, we consider everything from XO, TCXO, OCXO, DOCXO, to devar based designs - BVAs and others, and rubidiums, cesiums and Masers. What are reasonable price-tags for oscillators compared to various time transfer capable receiver? -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FYI: Galileo satellite recovered and transmitting navigation signals
Hi Dick, Its available for everyone. It will be as global as GPS. But currently under a system test phase. Three working satellites, one of the first four has some problems. Whats the status of that one now? Two new launched in August experienced a faulty orbit injection. http://ec.europa.eu/enterprise/policies/satnav/galileo/index_en.htm Should be more usable in a year or two. Will have performance much like GPSIII. -- Björn Dumb Question Time ... Is the Galileo available in North America or only for our overseas brethren ? Tnx, Dick, W1KSZ On 12/5/2014 8:16 AM, Edesio Costa e Silva wrote: Partial recovery of Galileo constellation: http://www.southgatearc.org/news/2014/december/galileo_satellite_recovered_and_transmitting_navigation_signals.htm Edésio ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Convert Stanford Research SR620 time-interval counter to SR625 ???
Prices used to be on their website. -- Björn div Originalmeddelande /divdivFrån: David I. Emery d...@dieconsulting.com /divdivDatum:2014-12-03 21:54 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] Convert Stanford Research SR620 time-interval counter to SR625 ??? /divdiv /divOn Wed, Dec 03, 2014 at 02:53:50PM -0500, Paul wrote: On Wed, Dec 3, 2014 at 12:08 PM, Neil Schroeder gign...@gmail.com wrote: I haven't really ever been able to talk to my prs10 via serial I took the easy way out and bought the interface board (directly from SRS). Do you have any rough number as to what they charged you for this ? -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LTE-Lite and - S14WI 1x4 GPS splitter
Hi! The splitter will not route 5V back out to another splitter port. Your gpsd(tcx)o antenna port is safe. -- Björn div Originalmeddelande /divdivFrån: cfo xne...@luna.dyndns.dk /divdivDatum:2014-11-29 08:53 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: [time-nuts] LTE-Lite and - S14WI 1x4 GPS splitter /divdiv /divGents I have a S14WI GPS antenna splitter w. Opt : Amplified + DC Bias Select + Ant Current monitor It's connected to a Maxrad 40dB ice cone timing antenna DS for the spliter here http://www.amtechs.co.jp/2_gps/pdf/S14WI_spec.pdf http://tinyurl.com/nfmpyqm Currently i have this connected : Port1 : Tbolt Port2 : Z3810A Port3 : Reserved KS Lucent (Waiting for TNC-BNC adapter) Port4 : Reserved for LTE-Lite (hope to connect today) Port3/4 have a 50ohm (BNC ethernet terminator) on right now As i read the DS , the splitter currently used the antenna power from Port1, to power the antenna, and Port2 is terminated w. 200ohm. I'm a bit unsure about the DS , but as i read it it will isolate Port4 from the antenna DC , as it draws power from Port1 (Tbolt) The LTE-Lite is 3v3 , and wouldn't like to get 5v on it's antenna. If anyone could have a quick glance , and verify my assumptions i'd be gratefull. TIA CFO -Denmark -- E-mail:xne...@luna.dyndns.dk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Divide by five
NTP does not pick the best clock. NTP finds the subset of clocks that track each other. NTP does indeed find the best clock from the subset of clocks which pass its sanity check, and then it uses only that one. There are several problems with that, and as we speak I'm developing a new algorithm which at least so far, gives much superior performance. You can read my musings about this here: http://phk.freebsd.dk/time/20141107.html My goal is to release the new NTP client before X-mas. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 Hi, Looking forward to testing the new NTP implementations! Many years ago I was bitten by a setup where ntpd did not exclude a falseticker. A normal PC (P2-450MHz) running linux (2.4.20ish-kernel with ppskit-patches) was set up with 4 or 5 good internet ntp-servers as reference. Two GPS-receivers were attached locally and configured as refclocks. One Trimble with external event input (driver29) and a Rockwell Jupiter with 1pps (hardpps) (driver31). By mistake I disconnected the Jupiter antenna cable. After about day (day and night, 24h), the clock had drifted ca 180ms. Even though all clocks but the Jupiter was agreeing within 1ms of true time. The clock followed the 1PPS of the drifting Jupiter oscillator, never minding the other sources. This could be since the jupiter 1pps, was configured as hardpps using the kerneldriver, instead of letting ntpd using the pps in softpps(?)-mode. Nevertheless I was a bit surprised that the computer continued to serve time claiming to be a S1-server, even if both local refclock and a number of external S1-servers said time was false. I dont know if recent ntpd and operating system versions still have this problem. Poul-Henning, for the updated server with local refclock, have you elaborated over 1) supporting multiple 1PPS-sources on the same server? 2) supporting a stable frequency source? (say a ocxo or rb, that are divided down to 1pps, 10pps or 1pp(minute), but the pulse is only stable not aligned to a utc-second transition, and have a small frequency offset.) -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WTB: GPS Antenna Splitter
From a geodetic antenna manufacturer, I got the recomendation to keep 1m separation between antennas. This was for a sub 5cm position application. But no white papers to quote... /Björn div Originalmeddelande /divdivFrån: Dave M dgmin...@mediacombb.net /divdivDatum:2014-10-08 17:40 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] WTB: GPS Antenna Splitter /divdiv /divBob, Thanks for that. My intent was to mount the antennas on yardarms on a mast. Both antennas will be at the same elevation, just separated horizontally by a couple feet (not 10ft). My concern (and I think you answered it) was how far apart could I place the antennas without having to do another survey when I switch them around. As an alternative, I could enter the antenna coordinated manually into each GPS when I switch antennas. That should avoid a new survey each time. Then, the distance between the antennas shouldn't matter. Thanks for the info!! Dave M Bob Camp wrote: Hi Missed the survey question… If a ns in free air is about 1 foot (30 cm), then you probably want a survey that is better than 6” to keep the error down. You do not want to have the antennas on top of each other, so yes, the GPS will need a survey / location each time you change antennas. If you go with the 10’ spacing, then you will get some pretty big jumps without switching the location. Bob On Oct 6, 2014, at 4:01 PM, Dave M dgmin...@mediacombb.net wrote: Does anyone in the group have, or can point me to, a low-cost (but not cheap) 2-port splitter for a GPS antenna? Those on Ebay are rather expensive. I have two GPSDO units, and have both an older timing antenna and a new choke ring antenna (Thanks, Pete L). I already have one 2-port splitter (working well), but my intent is to connect both antennas through the splitters and a couple coaxial relays so that I can, with the twist of a switch, allow me to run each GPS from a different antenna, or both from the same antenna. I would like to gather some data as to the differences between the two antennas. I know I could switch the connections manually, but I like the idea of a switch to sort of automate the connections, and I'd need another splitter anyway. Before I go to the trouble and expense of building upon this idea, are there any comments as to the value of the project? Some questions come to mind: I'm thinking about mounting both antennas on the same mast, at the same elevation, just separated by a couple feet. Any problems that I should be aware of by putting both antennas so close together? Will that small distance have a noticeable effect when switching a receiver from one antenna to the other? Will the GPS notice the difference and want to do another survey? Thanks for your comments. Dave M ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WTB: GPS Antenna Splitter
Hi, For those with a junk basket full of generic splitter/combiners and DC-blocks, go ahead and put something together. Note that most receivers wish to have a DC-load of around 200ohm to not raise antenna fault alarms. I have not found a dedicated GPS splitter cheaper than this from Mini-Circuits http://217.34.103.131/pdfs/ZAPD-2DC+.pdf When trolling the online auction sites, GPS Source and GPS Networking splitters are often less pricy than the HP/Agilent/Symmetricom/Microsemi ones. -- Björn Hi: This works great and has minimal cost. http://www.prc68.com/I/4GPS.shtml Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html John C. Westmoreland, P.E. wrote: Dave, Can you please let us know what you go with for your splitter choice? I noticed companies like EndRun Technologies use ones from these folks: http://gpsnetworking.com/GPS-antenna-splitters.asp TESSCO might stock those if you ask them. Regards, John W. On Mon, Oct 6, 2014 at 6:09 PM, Bob Camp kb...@n1k.org wrote: Hi Missed the survey question⦠If a ns in free air is about 1 foot (30 cm), then you probably want a survey that is better than 6â to keep the error down. You do not want to have the antennas on top of each other, so yes, the GPS will need a survey / location each time you change antennas. If you go with the 10â spacing, then you will get some pretty big jumps without switching the location. Bob On Oct 6, 2014, at 4:01 PM, Dave M dgmin...@mediacombb.net wrote: Does anyone in the group have, or can point me to, a low-cost (but not cheap) 2-port splitter for a GPS antenna? Those on Ebay are rather expensive. I have two GPSDO units, and have both an older timing antenna and a new choke ring antenna (Thanks, Pete L). I already have one 2-port splitter (working well), but my intent is to connect both antennas through the splitters and a couple coaxial relays so that I can, with the twist of a switch, allow me to run each GPS from a different antenna, or both from the same antenna. I would like to gather some data as to the differences between the two antennas. I know I could switch the connections manually, but I like the idea of a switch to sort of automate the connections, and I'd need another splitter anyway. Before I go to the trouble and expense of building upon this idea, are there any comments as to the value of the project? Some questions come to mind: I'm thinking about mounting both antennas on the same mast, at the same elevation, just separated by a couple feet. Any problems that I should be aware of by putting both antennas so close together? Will that small distance have a noticeable effect when switching a receiver from one antenna to the other? Will the GPS notice the difference and want to do another survey? Thanks for your comments. Dave M ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WTB: GPS Antenna Splitter
John, Note that Mini-Circuits seems to have made lots of other (GPS) splitters for Lucent and others. http://www.ebay.com/itm/Mini-Circuits-3-Way-Power-Splitter-Combiner-ZB3PD1-1575DC1S-/270834416075 -- Björn Björn, Thanks for letting us know - price isn't too bad - gotta love the P/N - ZAP D - makes you wonder if they have a sense of humor. Regards, John W. *Ordering,Pricing Availability Information* http://www.minicircuits.com/MCLStore/ModelPriceDisplay#*Select Country* http://www.minicircuits.com/MCLStore/ModelPriceDisplay#Part NumberData SheetDescriptionConnector TypeBracket OptionTRAvailability 1-4Price Each ($)Click to add to Shopping Cart1-45-910-24=25(+) Symbol indicates this Model is available as RoHS Compliant/Pb Free http://www.minicircuits.com/quality/environmental_introduction.html. ZAPD-2DC+ http://www.minicircuits.com/MCLStore/ModelPriceDisplay#Data Sheet http://www.minicircuits.com/pdfs/ZAPD-2DC+.pdfPower Divider, RoHSBNC --In Stock$ 74.95$ 74.95$ 64.95$ 63.95-ZAPD-2DC-N+ http://www.minicircuits.com/MCLStore/ModelPriceDisplay#Data Sheet http://www.minicircuits.com/pdfs/ZAPD-2DC+.pdfPower Divider, RoHSN--In Stock$ 79.95$ 79.95$ 69.95$ 68.95-ZAPD-2DC-S+ http://www.minicircuits.com/MCLStore/ModelPriceDisplay#Data Sheet http://www.minicircuits.com/pdfs/ZAPD-2DC+.pdfPower Divider, RoHSSMA--In Stock$ 74.95$ 74.95$ 64.95$ 63.95- On Tue, Oct 7, 2014 at 4:43 AM, Björn Gabrielsson b...@lysator.liu.se wrote: Hi, For those with a junk basket full of generic splitter/combiners and DC-blocks, go ahead and put something together. Note that most receivers wish to have a DC-load of around 200ohm to not raise antenna fault alarms. I have not found a dedicated GPS splitter cheaper than this from Mini-Circuits http://217.34.103.131/pdfs/ZAPD-2DC+.pdf When trolling the online auction sites, GPS Source and GPS Networking splitters are often less pricy than the HP/Agilent/Symmetricom/Microsemi ones. -- Björn Hi: This works great and has minimal cost. http://www.prc68.com/I/4GPS.shtml Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html John C. Westmoreland, P.E. wrote: Dave, Can you please let us know what you go with for your splitter choice? I noticed companies like EndRun Technologies use ones from these folks: http://gpsnetworking.com/GPS-antenna-splitters.asp TESSCO might stock those if you ask them. Regards, John W. On Mon, Oct 6, 2014 at 6:09 PM, Bob Camp kb...@n1k.org wrote: Hi Missed the survey questionââ¬Â¦ If a ns in free air is about 1 foot (30 cm), then you probably want a survey that is better than 6â⬠to keep the error down. You do not want to have the antennas on top of each other, so yes, the GPS will need a survey / location each time you change antennas. If you go with the 10ââ¬â¢ spacing, then you will get some pretty big jumps without switching the location. Bob On Oct 6, 2014, at 4:01 PM, Dave M dgmin...@mediacombb.net wrote: Does anyone in the group have, or can point me to, a low-cost (but not cheap) 2-port splitter for a GPS antenna? Those on Ebay are rather expensive. I have two GPSDO units, and have both an older timing antenna and a new choke ring antenna (Thanks, Pete L). I already have one 2-port splitter (working well), but my intent is to connect both antennas through the splitters and a couple coaxial relays so that I can, with the twist of a switch, allow me to run each GPS from a different antenna, or both from the same antenna. I would like to gather some data as to the differences between the two antennas. I know I could switch the connections manually, but I like the idea of a switch to sort of automate the connections, and I'd need another splitter anyway. Before I go to the trouble and expense of building upon this idea, are there any comments as to the value of the project? Some questions come to mind: I'm thinking about mounting both antennas on the same mast, at the same elevation, just separated by a couple feet. Any problems that I should be aware of by putting both antennas so close together? Will that small distance have a noticeable effect when switching a receiver from one antenna to the other? Will the GPS notice the difference and want to do another survey? Thanks for your comments. Dave M ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions
Re: [time-nuts] Oscilloquartz 3210 Cesium Standard
Hi Chris, Nice work! I can't help you with the faulty unit. There are others on the list with deeper insight in that OSA Cs core. Hope they have time to chime in. But I do have a telco variant of the same Cs core running in the basement. Its running continously (ocxo and ion pump) but its not burning the last fumes of Cs in the tube. This is since I don't see access or money available for a replacement tube. As you noted. With ocxo warm and cosy and the ion pump running it does not take long for Cs lock when needed. A mode where you can use the unit as premium ocxo (bva :-) ) standard that can be calibrated against the cs tube periodically as needed would suit my situation. However there are (at least) two mods needed. Because unless the cs tube burnes, there is no power to the 1) output buffer card. And thus no output signal. 2) potentiometer adjusting the bva frequency. Thus without cs tube running the bva is off freq. This design might have been a safe one in the original market. But I think modding the unit to let it run mostly as a very stable crystal standard is better for hobbyist use. Have others done these kind of mods to prolong the Cs tube life? Kind regards, Björn div Originalmeddelande /divdivFrån: Chris syseng.greenfi...@btconnect.com /divdivDatum:2014-09-29 22:43 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: [time-nuts] Oscilloquartz 3210 Cesium Standard /divdiv /divAnother update on progress: -- Now at the stage where two of the three 3210's are working. The fault that was blowing the line fuse turned out to be a shorted reservoir cap. Managed to find an Ebay seller in Greece with exactly the same voltage, capacity and outline, though different manufacturer. The caps have a stud mount at the base of the can, so not easy to find, but bought four at just over 3 ukp each and replaced both caps in the psu, leaving two for spares. From cold, the spec is up to 90 minutes warmup time, but if the OCXO and pump have been running for some time, both units lock up within 4 minutes. Have done some setup. For example, normalised the gains and offsets in the preamps as per the manual and both units show the expected preamp level of ~165mV and 2nd harmonic amplitude of 9-10 on the meter, so assume both tubes are in good condition. None of the settings were very far out. Took a set of measurements from one of the good units and the faulty for comparison, with similar results, Good unit as follows, but faulty unit more or less the same: Ion pump = EHT ok, meter = 0 Electron multiplier EHT voltage = 1800 volts, (100Mohm hv probe on o/p wire) Cesium oven = Not open circuit, voltage = 5.5 volts Ioniser = not open circuit, 1 volt p-p square wave at ~26KHz Synthesiser output = 12.6317715, follows variation in OCXO and in lock Backplane test points, tpb, tpc = 8.2 volts p-p square wave, ~137 Hz. Multiplier 12.6... MHz input = 2v p-p (Scope) Multiplier 137Hz input = 2.25v p-p (Scope) Multiplier 180MHz output = +26DBm (HP 3406A rf voltmeter + 20DB attenuator) Microwave tap on waveguide = -14.5DBm, threaded attenuator works (HP432A, 478A) The 3406 and 432 are quite old and the sensor head is even older, but should be reasonably accurate. The 478A head was coupled to the microwave tap using a ~3 inch length of rigid coax, so not much attenuation. Hopefully, these figures may help others trying to debug these standards, but if there's anything i've missed, please let me know. For the faulty unit, even with all the levels as expected, there is still no signal, nor 2nd harmonic, even with the preamp gain turned up to max. Connected a Fluke electrometer in series with the preamp input socket, but the current is at least 100 times down on 1nA. Looks like the tube is completely lifed, or has an internal fault. /FX: Have visions of a sad, faithful and slowly dying 3210 left for decades in a rack, in the dark, powered up, but long forgotten after the accurate reference it provided ceased to be used anywhere in the organisation. A ship adrift for thousands of years, but all systems still at least partially working and waiting to be discovered :-). So what else am I missing in this puzzle ?... Regards, Chris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A question about anomolous Alan Deviation Measurements.
Morrie, Be aware that the PM66 (80,81,90) are badged versions of Pendulum CNT (80,81,90). Pendulum was based in Stockholm Sweden, before a merger and subsequent close of the site. :-( Did you use the built in adev calculations? Logging/processing with TimeLab might be easier to analyse for the list experts. Also look for comments from Magnus in the archive. -- Björn div Originalmeddelande /divdivFrån: Tom Van Baak t...@leapsecond.com /divdivDatum:2014-09-22 12:39 (GMT+02:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] A question about anomolous Alan Deviation Measurements. /divdiv /divHi Morrie, I suspect your PM6690 is working correctly. High-end counters give better-looking results when the two frequencies (DUT and REF) are not exactly the same. I don't know if the Fluke documentation mentions it. But there is a short description in the HP/Agilent manuals: http://leapsecond.com/pages/53132/53132-reduced-resolution.gif See also: https://www.febo.com/pipermail/time-nuts/2013-August/079662.html Remember that you are not measuring the Allan deviation of a OCXO alone -- your measurements are the Allan deviation of the DUT + the counter + the REF. When you get near the noise floor it becomes very important how much each of the three pieces contribute to the final number. The counter noise may differ between time interval, time interval average, and frequency modes. Note also that your 6e-12 number may be skewed by undocumented oversampling or averaging done inside the counter. That is, the true ADEV may be higher than 6e-12. But it sounds like you are just making pair-wise comparisons among OCXO so this is probably not a concern. To make short-term measurements with significantly higher resolution you may have to switch to an instrument designed to measure oscillator noise. A classic example is: http://www.wriley.com/A%20Small%20DMTD%20System.pdf /tvb - Original Message - From: mor...@iometric.com To: time-nuts@febo.com Sent: Sunday, September 21, 2014 7:55 PM Subject: [time-nuts] A question about anomolous Alan Deviation Measurements. I am using a Fluke PM6690 counter measure the Alan Deviation of various pairs of 10 MHz OCXO's in use in my lab. I discovered that I can measure a (tau = 1 sec) low value of say 6.0E-12 on a good set, but only If the crystals are tweaked so the delta is some 0.5 ppm. If they crystals are tweaked to be within a mH, then the Alan Deviation zooms to about 5 times higher. I suspect a flaw in my PM5590 unit or in its design, and I guess will hunt around for something better. Does anyone have experience with this phenomena? Does one always have to separate the clocks being compared to avoid this beating? Thanks, Morrie Altmejd ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Looking for the spec on a chokering
Look for AERAT2775_42+CR at http://www.ngs.noaa.gov/ANTCAL/Antennas.jsp?manu=AeroAntenna http://www.ngs.noaa.gov/ANTCAL/LoadImage?name=AERAT2775_42%2BCR%2BNONE.gif Even if the phase offsets are different from what is printed on your chokering, they do look similar. Do you have the antenna also, or only the chokering? What spec's are you looking for? /Björn AeroAntenna AT27751995 https://plus.google.com/u/0/photos/111617808980322733757/albums/6058672650441867201 -pete ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS antenna in snowy environment (was: LEA-6T, Software.)
Dan, The classic Aeroantenna SPIKE snow cone. http://www.ngs.noaa.gov/ANTCAL/LoadImage?name=AERAT1675_120%2BSPKE.t.jpg The old Ashtech snow cone http://www.ngs.noaa.gov/ANTCAL/LoadImage?name=ASH700936A_M%2BNONE.t.jpg Both of the above will keep birds looking for another place to rest. http://www.ngs.noaa.gov/ANTCAL/LoadImage?name=ASH701945C_M%2BSCIS.s.jpg http://www.ngs.noaa.gov/ANTCAL/LoadImage?name=TPSCR.G5%2BTPSH.gif http://www.ngs.noaa.gov/ANTCAL/LoadImage?name=TPSPN.A5%2BSCIT.ave These spherical cones will impact the signals less, but they do give birds a rest/watch-place. See the middle url, which shows the drawing, and where the antenna phase center is put in the center of the (half)-sphere. The swedish COORS network - called SWEPOS - are using at least two versions of snow cones made from clear acrylic. http://swepos.lmv.lm.se/stationer/0opp.htm http://swepos.lmv.lm.se/stationer/0bor.htm But I doubt very much that a usual timing receiver will notice the difference. -- Björn Björn, Can you provide links to some examples? A picture or two would be great! Attila, Almost all the snow we get accumulates. However it does settle, even then by mid February it's not unusual to see 4 or 5 feet on the ground... However, that raises a good questions, in terms of cones and shedding snow. I wonder how a straight slender vertical pipe with capped end would work. Say 6 feet long. Let the snow build on the top. You might loose a few degrees of sky view above it, but how detrimental would that be? Lots to think about before winter! :) Dan ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS antenna in snowy environment (was: LEA-6T Software.)
Note that the high accurcy geodetic snow cones for chokering antenns have moved towards thin spherical designs. -- Björn div Originalmeddelande /divdivFrån: Chris Albertson albertson.ch...@gmail.com /divdivDatum:2014-08-28 15:17 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] GPS antenna in snowy environment (was: LEA-6T Software.) /divdiv /divThe same shape that keeps bird off the antenna also keeps birds off. It is worth getting the tall cone shape no matter where you live. On Thu, Aug 28, 2014 at 6:04 AM, Attila Kinali att...@kinali.ch wrote: On Mon, 25 Aug 2014 10:48:51 -0400 Dan Kemppainen d...@irtelemetrics.com wrote: Also, I have a low cost antenna coming. It's one of the Synergy systems puck type amplified antennas. I remember some time back a bit of chatter about improving GPS antennas for timing, by providing some sort of guard ring or choke to prevent low angle reception. Are there any good links anyone could provide on what may be worth building or playing with. Keep in mind, I live in snow country (~300 inches/year) so a something that gathers a lot of snow could be undesirable! :) How much snow you get is mostly irrelevant. It's more important how much accumulates ;-) A cone hat over your antenna should solve quite a bit of the issue. The problem is, that you need quite a steep cone or you need to heat it constantly above 0°C, as snow tends to stick to everything, even smooth walls. Maybe also worth a try would be to grease the cone. But i've only heard of that and never seen it in action. So i cannot tell whether that helps in any way. Attila Kinali -- I pity people who can't find laughter or at least some bit of amusement in the little doings of the day. I believe I could find something ridiculous even in the saddest moment, if necessary. It has nothing to do with being superficial. It's a matter of joy in life. -- Sophie Scholl ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Ublox neo-7M GPS
Have not tried myself, but there are instructions around describing how to load T-firmware into non T ublox models. There also seem to be possible to patch the program ram to enable looked features on models without flash reprogramming capability. /Björn div Originalmeddelande /divdivFrån: Tony tn...@toneh.demon.co.uk /divdivDatum:2014-08-22 03:45 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] Ublox neo-7M GPS /divdiv /divOn 21/08/2014 08:13, Ed Palmer wrote: But, timing receivers do have features that can improve performance over navigation receivers. Some that come to mind are position hold mode, TRAIM, maintaining performance with only one satellite locked, sawtooth correction, and precision survey. I haven't dug through the Ublox data sheets to see which ones they support. I just tried sending various TMODE and TMODE2 configuration messages to the NEO-7M. These allow you to select 'Disabled' 'Survey In' and 'Fixed Mode' where you can specify the receiver's lattitude and longitude. Not surprisingly, it replied with negative acknowledgements each time so they presumably aren't supported in this receiver. I was using the ublox u-center tool which should ensure the messages were formatted correctly. It's very unlikely, but its conceivable that it does actually support these modes but some other required configuration hadn't been done, causing a conflict. I've not yet found any detailed documentation specifying exactly which messages/features these modules do support. Tony H ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Fwd: CGSIC: FW: The next GPS Launch
Its positive that the SVs has exceeded contract design life saving money with less launches. But the launch on failure policy has also delayed the modernization of the constellation - even if the last batch of 2R were retrofitted with some new signals. I imagine that having SVs sitting in storage for 5+(more?) years also has its implications with keeping support contracts etc. Cheers, Björn div Originalmeddelande /divdivFrån: Magnus Danielson mag...@rubidium.dyndns.org /divdivDatum:2014-07-29 20:46 (GMT+01:00) /divdivTill: time-nuts@febo.com /divdivRubrik: Re: [time-nuts] Fwd: CGSIC: FW: The next GPS Launch /divdiv /divJohn, It has delayed the launching of birds, as the old ones does not die of quick enough for the planned schematic to maintain 24 birds, instead we see 30-32 birds active for many years, and some being off air backups. On the other hand, it gives more time to adjust the new birds with new signals. Cheers, Magnus On 07/29/2014 08:42 PM, John Allen wrote: Hi Magnus et al - just FYI: 2 1/2 times the design lifetime is not unusual for satellites. More of the Ham Oscar satellites have exceeded their lifetime by that much or more. (Sorry, no facts handy). It saves us USA taxpayers money when they last that long! Regards, John K1AE Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: Tuesday, July 29, 2014 2:12 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Fwd: CGSIC: FW: The next GPS Launch Fellow time-nuts, Things will shift in the sky. Lot's of changes. SVN-33 is being decommissioned after 17.5 years of operation, with a 7 years designed lifetime, that's 2.5 times the operational lifetime, and it's being decommissioned in a controlled fashion. Respect. Cheers, Magnus Original Message Subject: CGSIC: FW: The next GPS Launch Date: Tue, 29 Jul 2014 17:23:10 + From: Civil Global Positioning System Service Interface Committee (CGSIC) cg...@cgls.uscg.mil Reply-To: cg...@cgls.uscg.mil To: cg...@cgls.uscg.mil cg...@cgls.uscg.mil All CGSIC: The Air Force is set to launch the 7th GPS IIF satellite from Cape Canaveral Air Force Station in Florida. Delta IV GPS IIF-7 Mission Overview: Atlas V GPS IIF-7 Mission Brochure: http://www.ulalaunch.com/uploads/docs/Mission_Booklets/AV/av_GPSIIF7_MOB.pdf Rocket/Payload: An Atlas V 401 will launch the GPS IIF-7 mission for the U.S. Air Force. Date/Site/Launch Time: Friday, Aug. 1, 2014, from Space Launch Complex (SLC)-41 at Cape Canaveral Air Force Station, Fla. The 18-minute launch window opens at 11:23 p.m. EDT. Viewing the Launch by Webcast: The live webcast will begin at 11:03 p.m. EDT. GPS IIF-7 is one of the next-generation GPS satellites, incorporating various improvements to provide greater accuracy, increased signals, and enhanced performance for users. Launch Updates: To keep up to speed with updates to the launch countdown, dial the ULA launch hotline at 1-877-852-4321 or join the conversation at www.facebook.com/ulalaunch and twitter.com/ulalaunch; hashtag #GPSIIF7. The Air Force Second Space Operations Squadron indicates that IIF-7, SVN-68/PRN-3, will replace SVN-43 in the F plane slot 3 (F3). SVN-43 will be re-phased from F3 to the F2F slot to replace SVN-26. SVN-33 will be taken out of the operational constellation the day after SVN-68 launch and sent to Launch, Anomaly and Disposal Operations (LADO). SVN-33 was launched on 09 April 1996 successfully serving over 17.5 years, 10.5 years beyond its design life, due to the diligent efforts of the men and women of the U.S. Air Force. SVN-26 will back-up SVN-43 once it completes its re-phase journey. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Lightning for time-transfer... now also positioning...
Hi, A followup on Tom's thread on blixtortnung (lightning location) and the possible use of lightning as a time transfer method. It seems Darpa is reseaching positioning based on lightning. https://medium.com/war-is-boring/gps-not-working-try-using-lightning-to-find-your-way-e75144bcf4dd /Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO standard interface?
Novatel has two versions of each message one binary (ending with B) and one ASCII (ending with A). That is one way of catering to both the interactive use and the clean software side of the problem. Javad (GRIL now GREIS) is my personal favorite. Your commands are ascii, often very short. The output messages are usually binary but with a prefix and ending linefeed that makes it easy to monitor which messages are active in a plain console terminal. The binary parts are also constructed in such a way that makes it very easy to receive them in normal structs. my two öre. /Björn I dislike TSIP quite a bit. It's a disaster in my opinion if you are not intimately familiar already with the Trimble binary commands, and exists in a number of inconsistent and non-compatible dialects as far as I know. No way for a human to enter a simple command in a simple text terminal, you have to have everything translated by some application. I know the software folks like binary better than ASCII, because parsing binary commands can theoretically be done with less effort. I think effort == results. There is SatStat, GPSCon, and Ulrich's great Z38xx control program for human readable SCPI commands besides the good old ASCII terminals. HP leads the way with GPIB/SCPI in my opinion. But it's like religion, everyone thinks theirs is the right one, and everyone else is on the wrong path. bye, Said In a message dated 6/26/2014 14:01:35 Pacific Daylight Time, hol...@hotmail.com writes: There are TSIP commands for doing all those things. It should be fairly easy to adapt them to control your hardware and whatever GPS receiver you are using. The nice thing about implementing a TSIP interface is being able to use existing programs like Tboltmon and Lady Heather (over 30,000 lines of code) to monitor and control it. Also NTP knows how to talk TSIP. I am planning on the output of at least position, corrected phase error, DAC value, ambient temperature, and a few other things. I also see a need to read and write the PID gain and damping factors, but that may just have to be a custom tty interface. It may be that I need to have a pass-through mode to give direct access to the receiver for triggering site survey, etc. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low cost GPS module for 100ns timestamping error
On Mon, May 12, 2014 at 3:03 AM, Tony tn...@toneh.demon.co.uk wrote: Unfortunately they use way too much power - 800mW maximum compared to 50mW for a UBLOX MAX-7c which are around $15. It also is specified at 50ns rms, 99% 100ns. It appears that most, if not all, the timing type modules are higher power as well as more expensive; unless anyone has any better suggestions it looks like I'll have to stick to navigation type modules. I think they use more power because a timing mode GPS is used at a fixed location and so is likely to have AC mains power available and if a backup battery is needed it can be a large gell cell type More likely its lower power needs is because the uBlox tech is 10+ years more recent than the old Motorola stuff. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS antenna length correction
Michael, Lever arms are used to move a measurement to where its needed. Typically when an INS uses a GPS measurement where the antenna is some meters away from the INS calculation reference point. Its not applicable to the antenna cable length problem. The GPS needs to calculate x,y,z and t for each epoch. However the receiver can't distinguish between the antenna-cable delay and a bias/time-error in the receiver clock. And as a result the GPS 1PPS output will be biased by this delay. x,y,z is not affected by the time-delay between the antenna phase-center and the receiver. /Björn The ability to correct the position depends on the receiver. Some receivers have a correction known as the lever arm correction. This is the vector difference between the antenna centroid and there is also a variable to enter the cable length. Between these two corrections the receiver time and position is the same as that at the antenna centroid. These corrections are normally found on kinematic and military receivers but may be on any - check the specs / owners manuals. Michael / K7HIL On Mon, Apr 28, 2014 at 8:20 AM, Hal Murray hmur...@megapathdsl.net wrote: br...@lloyd.com said: As I think about the geometry of satellite position and path length, it seems to me that, since the geometry is determined by the antenna position and not the receiver position, additional antenna cable introduces a fixed delay value and hence a fixed constant that gets added to each path regardless of direction. It seems to me that this would produce a much fuzzier solution to position and/or variation in timing. Knowing cable length and propagation velocity, would allow the software to subtract that constant from all ranges and thus provide a more correct position and time solution. Is this not the case? Does it do something simpler but good enough? If you just do the normal calculations, you get the location of the antenna as though you were there a while ago. If you know the delay in the cable, you can correct the time. There is no way to correct the position. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS antenna length correction
As mentioned earlier the position of the receiver is indeterminate unless the vector displacement from the antenna to the receiver is accounted for. Accounting for the cable delay will only correct the absolute time. Imagine a 100m antenna feed line; the receiver could be anywhere within 100m of the antenna (even above it or at it). The algorithm that computes position needs to know this. It is possible the programmer assumes that the receiver is directely below the antenna; but I don't know what programmers assume. It would be safest to display the position of the antenna. This discussion suggests that manufacturers should make it clear that the position is of the antenna or otherwise The receiver computes the position of the antenna phase center. The position of the receiver is not of interest and also cannot be computed. People who do not accept this, should keep their antenna cables really short... ;-) /Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low SNR GPS reception and cheap LNAs
On Fri, 25 Apr 2014 12:21:04 -0400 (EDT) gandal...@aol.com wrote: Coincidentally, I came across this earlier today when looking for some MMIC data, perhaps it might be worth a look?... http://lna4all.blogspot.co.uk/ Now that's almost perfect! Only two modifications and it does what i need it to do! Thanks a lot! Next time I will try a ZX60-P162LN+ from Mini-Circuits. http://217.34.103.131/pages/s-params/ZX60-P162LN+_GRAPHS.pdf only $54 for a boxed unit. Bias-T needed to. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS W/10KHz
Dennis, All I was pointing out is that at a higher output frequency, like 10 kpps, the frequency of the quantization saw tooth error will almost always be much higher as well. There's no need for the digital correction since averaging over a relatively short period, like in the loop filter of an appropriate analog PLL, will almost always be sufficient to smooth the sawtooth. The sawtooth correction is the difference between where the receiver would wish to place the edge and where its known limited resolution electronics lets it put the edge. The receiver wish is based on the timesolution from the last measurement. In the Jupiter this is done at 1Hz maximum. The sawtooth correction will apply the same for all 10k (pos or neg) edges in the 10kHz signal during that one second. There are effects that are not easily filtered away in the analog domain. See the archives and http://www.leapsecond.com/pages/m12/sawtooth.htm kind regards, Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WAAS.....
Hi Brian! Hmmm... should I finish the thread before commenting... The scenario has been discussed on the list before. There are publications from Zyfer (fei) on Waas timing with a fixed dish antenna. There is also a Fenton(Novatel) patent. -- Björn div Originalmeddelande /divdivFrån: Brian, WA1ZMS wa1...@att.net /divdivDatum:2014-01-08 09:25 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] WAAS. /divdiv /divIn this case the timing rcvrs are located all with in a 20km radius with fixed known surveyed locations. The problem is GPS jamming that happens at random times. So one what if idea is to use a WAAS enabled rcvr and a yet to be selected parabolic antenna to point at a given WAAS sat. The concept is to give all rcvrs a single common view for critcal timing use in a comm system. The ultimate goal is to try and reduce the number of times when full sky view GPS antennas are victims of GPS band interference. This is only a half-baked idea of mine (in my day-job) but wanted Time Nuts feedback to see if it has any merit at all. BTW, the system has Rb for hold-over when there are problems but the frequent system error alarms indicating hold-over events is what I/we would like to reduce. New SNMP traps could mask off the events, but being an RF guy.I was thinking about a HW solution. :- ) -Brian, WA1ZMS/4 iPhone On Jan 7, 2014, at 11:05 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: Brian, On 2014-01-08 02:25, Brian, WA1ZMS wrote: Hypothetical question For a given set of GPS timing grade receivers at multiple locations, is there any advantage by limiting allowable SVN numbers to only be the WAAS satellites? Well, if you do common view GPS comparision and is not into monitoring observables separately (which is recommended), then there is some use for it, as you configure the WAAS acceptance statically and only need to update it once a new bird becomes available or one disappears. However, I wonder if they are any good for that purpose anyway. So, in a more general way, I'd say no. More importantly, what are you trying to achieve? Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Trimble Thunderbolt 1pps
The RIPE ntp system does a little bit of this. http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver43.html -- Björn div Originalmeddelande /divdivFrån: Brian Lloyd br...@lloyd.com /divdivDatum:2014-01-04 19:26 (GMT+01:00) /divdivTill: Discussion of precise time and frequency measurement time-nuts@febo.com /divdivRubrik: Re: [time-nuts] Trimble Thunderbolt 1pps /divdiv /divOn Sat, Jan 4, 2014 at 12:05 PM, Hal Murray hmur...@megapathdsl.net wrote: albertson.ch...@gmail.com said: Where those using the cat-5 wire as a twisted pair? If sothat's cheating Yes. I was thinking that 4 pairs would be Rx, Tx, PPS, and power. If I need Ethernet, I'll pull another Cat-5. Pulse quality of single-ended RS232 over unbalanced twisted pair is going to be pretty bad beyond a few feet. If you want to transport the 1pps over twisted pair there are a couple of options: 1. A BALUN. There are lots of 75ohm-to-CAT5 BALUNs out there specifically for transporting NTSC video over CAT-5. At the far end use another BALUN before running into a TTL-to-RS232 line driver. There should be sufficient drive without too much extra hardware. (Terminate into 75 ohms tho'.) 2. Use an RS-422 driver. This will accept the TTL-level 1pps in and produce a nice differential output to drive the twisted pair. You can find serial cards that have RS-422 line receivers that will plug directly into the PC. 3. Simply use coax that is properly terminated at the far end to drive a TTL-to-RS232 line driver right at the computer's RS-232 input. All three of these should result in an acceptable 1pps with jitter levels lower than the timing resolution of the NTP server you are running on the target machine. -- Brian Lloyd, WB6RQN/J79BPL 706 Flightline Drive Spring Branch, TX 78070 br...@lloyd.com +1.916.877.5067 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT : different Rx and Tx baud rate on same port
Tom, Bob James, (will answer in one response, to save some bandwidth) I have a GPS receiver that is hard configured at 19200baud one way, and 76800baud the other. The most convinient would be a USB serial adapter, but ExpressCard or PC-CARD is also ok. PCI/PCIE is better than nothing. HW is a laptop. Preferably a modern one. But one with PCMCIA is also ok. I have a (binary only) windows program that I need to run. Windows version either XP or preferably win7. But I am interested in running the adapter in linux also. In Linux I can arrange with combining two serial ports, since I have the source. In MSWindows I do not have that luxuary. Have seen reference to the bb-elec stuff. The closest I found now is http://www.bb-elec.com/Products/Datasheets/232brc_0812DSds.pdf which convert baud rates, but I think not in the way I wish. I have looked but not fully digested if the advanced async/sync serial adapters can do split baud rates. http://www.commtech-fastcom.com/data_sheets/sab82532.pdf It seems there was a time in the distant past where this was more common. Setting the input baud rate to zero was a mechanism to allow for split baud rates. Clarifications in this volume of IEEE Std 1003.1-2001 have made it possible to determine whether split rates are supported and to support them without having to treat zero as a special case. http://manpages.ubuntu.com/manpages/hardy/man3/cfgetispeed.3posix.html Here is an (obsolete, but with documentation from 2009 its not ancient) serial controller from Exar The Independent TX/RX Baud Rate Generator feature allows the transmitter and receiver to operate at different baud rates. http://www.exar.com/connectivity/uart-and-bridging-solutions/8-bit-vlio-uarts/xr16m680 Looking at the stty unix command. It seems clear that split baud rates has been supported at one time. http://www.openbsd.org/cgi-bin/man.cgi?query=sttysektion=1 ispeed number Set terminal input baud rate to the number given, if possible. If the input baud rate is set to zero, the input baud rate is set to the value of the output baud rate. ospeed number Set terminal output baud rate to the number given, if possible. If the output baud rate is set to zero, modem control is no longer asserted. speed number This sets both ispeed and ospeed to number. With this much hinting, I was hoping there was still some hardware out there supporting split baud rates. kind regards, Björn Björn, If you can't find a black box that does this, just use two serial ports: Rx from one and the Tx from the other. On the software side it means opening two devices, but that shouldn't be hard to handle. Note bb-elec.com used to make a cute 4-port serial concentrator that would allow you to configure different baud rates in/out, but I see that's no longer a current product. Of course you could do all this with a micro or SBC, but I assume you're looking for a turn-key device rather than a homebrew project. /tvb - Original Message - From: Björn b...@lysator.liu.se To: time-nuts@febo.com Sent: Friday, December 06, 2013 4:14 PM Subject: [time-nuts] OT : different Rx and Tx baud rate on same port Hi, I am looking for current serial adapters that support split baud rates. That is different input and output baud rate. Grateful for suggestions! kind regards, Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT : different Rx and Tx baud rate on same port
Paul, The posix C library supports this. http://linux.die.net/man/3/tcsetattr with the cfsetispeed and cfsetospeed functions. Yes, but do the serial device drivers (still) support it? Is there hardware supporting it? -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] OT : different Rx and Tx baud rate on same port
Hi, I am looking for current serial adapters that support split baud rates. That is different input and output baud rate. Grateful for suggestions! kind regards, Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Strange 100ns jumps on Motorola M12+T
Hi Stephan, Using a single antenna and splitting it is an idea, but then I still need to devise something to inject the antenna DC power at the other end of the splitter etc. And, we are trying to measure the relative offset between the antenna/receiver pairs for calibration. Most generic RF splitters I have worked with have DC connections between all ports. So you would need to connect one GPS directly to the splitter and then DC block the other two receivers. This is taken care of if you buy a splitter designed for GPS use. Look in the archives. GPS networking, GPS Source, HP/Agilent/Symmetricom/... all do splitters. http://gpsnetworking.com/datasheet%20replacements/LDCBS1X4.pdf Phase unbalance between the ports of 1 deg, should not contribute to you error budget significantly. kind regards, Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Time stamping with a PICPET
Chris, So basically what you are proposing is an NTP reference clock that queries a known good external clock at semi-random intervals. The query method is to send a pulse then read the time from the external clock. GPS is a push device. It just sends data forever. What you are wanting is a pull device, one that will tell you the absolute time of a pulse. It would not be hard to build. Get a 32 bit counter that is driven by a 10MHz GPSDO. then a pulse will latch the counter. You'd need a very fast logic family if you plan to count nanoseconds. This is already available even in some small mass market receivers. See the uBlox Lea-6T and other uBlox receivers. Time mark of external event inputs This has also been available in high quality L1 receivers and L1/L2 receivers used for airborne photogrammetry. Read the text on page 40 and onwards of the Ashtech G12 manual http://goo.gl/Oc1htQ The same feature is also available in all(?) the bus interface T/F cards from Bancomm/Datum/Symmetricom/Truetime/Spectracom/KSI/Odetics etc. Event Time Capture. An Event Time Capture feature provides a means of latching time for an external event input. from http://www.symmetricom.com/products/bus-level-timing/legacy-pci/bc635PCI-U-IRIG/ The query would not be once per second. NTP would use its normal method to determine the interval, usually it is much longer than one second. I bet there must already be an NTP ref clock that is based on query. that could be a starting place. See the Palisade refclock driver http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver29.html kind regards, Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Splitter for GPS antenna suggestions?
Charles, Bob, Bob wrote: The Symmetricom / HP splitters are way more than just a splitter. They have an amp and some filtering in addition to the split. They also pass DC from only one port and correctly DC terminate the other ports so you don't get an antenna missing error. And they were designed for precision timing systems, so thought was given to minimum propagation time and to equal delay between channels. PT is about 20nS, and very consistent channel-to-channel. Best regards, Charles Here is a splitter that is way more than the Symmetricom/HP ones. http://www.gpssource.com/files/S1X4WI-Datasheet-005.pdf The S14wi has lower delay. Has options to pass DC from any one port. Will remove the DC load so that the splitter does not hide from the GPS receiver that the antenna really is broken/gone missing. In the only national time lab I have visited, there was Cesiums, H-masers and rubidiums. Do not remember seeing L1-only receiver. But many dual/tripple frequency receivers. Thus the antenna distribution was set up for wide band reception. The S14WI was available from some sources (Ebay 190645191204). At $100 it was a steal compared to most other options. The Mini-circuits generic splitters I have checked has had common DC path on all ports. That means you need a bias-T with resistor load or at least a DC-block on the ports you do not feed the antenna LNA from. kind regards, Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Splitter for GPS antenna suggestions?
Hi Frank, HP/Agilent/Symmetricom splitters work well. GPS networking, GPS source are usually covering both L1 L2, which you do not need with your current receivers (the ones you mention). HP/Agilent/Symmetricom is often more expensive on the auction site, even though they are less advanced. Mini-circuits and such generic rf-splitters also works well, but then you might need some dc-blocks, bias-t's etc. Search the archives. Google for splitter site:febo.com or something similarly. kind regards, Björn Hi, I want to see if it is possible to feed both the Trimble TB and the Jackson Labs Fury from the existing antenna. It appears both the TB and the Fury are 5vdc antenna power. Checked the auction site for splitters, but before I randomly buy anything, could someone please suggest what they use that works? Thanks, and 73 Frank KJ4OLL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] trimble antenna connector
Hi Eric, Because they were designed to use cheap 75ohm cable-tv/satellite cables which usually go with F connectors. The companion Bullet antenna also have F connector. From the Tbolt manual RG-59 is a 75 ohm coaxial cable. The ThunderBolt and Bullet II HE antenna are compatible with 75 ohm cable. Compared to most 50 ohm cable, 75 ohm cable provides superior transmissibility for the 1.5 GHz GPS signal and a better quality cable for the price. Mismatched impedance is not a problem. -- Björn why do older thunderbolts use an F connector for the antenna? (the current version uses a BNC). It seems like it needlessly complicates installation at a base station. I've always wondered this. -- --Eric _ Eric Garner ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Req: Decent GPS AntennaActive/Passive Recommendation
Hi Bob, Doppler shift is +-3.5kHz. Bandwidth for the CA signal is ca 2MHz, narrow correlator receivers takes in 10MHz to mitigate multipath errors. So doppler spread is about 1/1000 of the spread spectrum signal. Does the filter delay really change that much with 7kHz total doppler variation? For Glonass receivers this is more of a problem, since Glonass is a FDMA system. -- Björn Hi Once the sat's all arrive at the antenna, a fixed delay (in general) does not impact things a lot. The gotcha with the filter is that it's delay is unequal across the GPS band. Doppler puts the sat's all over the place. That gives some more delay than others. Having unequal delay on sats is indeed an issue. As the filter changes delay with temperature things will move a bit more. Since it's a frequency high on approach / low on departure sort of thing it will average out on each pass. The main impact would be an increase in wander. Bob On Sep 16, 2013, at 1:24 AM, David J Taylor david-tay...@blueyonder.co.uk wrote: From: Bob Camp Hi All of the ones I've opened up or seen dis-assembled have had the ceramic plate antennas in them. That very much surprised me early on, since I *assumed* they had something fancy inside based on their shape. No argument about the filtering, I'm not sure if the temp-co of filter delay on an exposed antenna makes it a plus or a minus . Bob === .. and would the true time-nut add the delay through the filter to the delay in the feeder co-ax? I suppose that means you could only buy an antenna with a stated, calibrated delay? Limits the choice, a little! Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NTP/1-PPS/RS232 question
david-tay...@blueyonder.co.uk said: Although, IIRC from discussions with Dave Hart, the Windows port can only accept the normal positive-going signal on the DCD line. The devices I've tested all have positive going signals. Pulse width is typically 100 or 200 milliseconds, with a few receivers giving a much shorter pulse. Low cost GPS receivers usually have long PPS pulses. Fancy GPS receivers, like the TBolt or Z3801A have short pulses, ballpark of 10 microseconds. The short pulses sometimes don't get captured by the standard PPS software. The PTTI 1PPS is defined in http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf It is 20us long and common in some applications. However the voltage levels are a bit high... -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NTP/1-PPS/RS232 question
b...@lysator.liu.se said: The PTTI 1PPS is defined in http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf It is 20us long and common in some applications. However the voltage levels are a bit high... The section I saw said 10 V nominal, +1, -2. That's 8-11 V. I think that would work fine with a RS-232 receiver. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NTP/1-PPS/RS232 question
b...@lysator.liu.se said: The PTTI 1PPS is defined in http://www.navcen.uscg.gov/pdf/gps/ICD-GPS-060B.pdf It is 20us long and common in some applications. However the voltage levels are a bit high... The section I saw said 10 V nominal, +1, -2. That's 8-11 V. I think that would work fine with a RS-232 receiver. Yes, but driving 10V into _50ohms_ is a lot of power for a modern receiver... /Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Star Box
Hi Bob Joe, The CMC Allstar was a high quality 12 channel L1 receiver. There was even an option for the DGPS version to have an onboard OCXO. Joe, does your have that or the ordinary Rakon TCXO? Shure the Allstar is not a high sensitivity receiver so do not try indoor navigation with this receiver. However, measurement quality with a decent antenna/antenna siting - it will still give the modern uBlox receivers a run. Not to bad for a 10-15 year old product. It is also nice - as Magnus pointed out - in that it driven by a 10MHz oscillator onboard. Compared to a uBlox based GPSDO it does not need the 1PPS/phase detector. These Allstars used for DGPS, were - I suspect - the prime reason for the CMC/Novatel branded AT575-90 L1 Choke ring antennas we have seen available. -- Björn Hi Pretty much everything made from silicon goes through 3-4 year cycles. Anything that's 10 years old is a couple of cycles behind. It's probably not going to work as well as an LEA-6T or even a LEA-5T. It might be competitive with a 4T or a 3T. Bob On Aug 15, 2013, at 10:47 PM, Joseph Gray jg...@zianet.com wrote: I just picked up a Star Box for $10. It has an Allstar DGPS board inside. I saw several mentions of similar boards in the archives and I have found some documentation on the net. Has anyone actually used one of these in a GPSDO? Does it work any better than the usual Motorola, Rockwell, or other available boards? The other thought is, since this is a DGPS board, how difficult would it be to use it to obtain a more accurate position fix? Or do I need other GPS boards to correlate this one with? I'll admit that so far, I have only skimmed the documentation that I downloaded. If I need to RTFM for my answers, just tell me so. Some data on what I have: Star Box Part No. 100-600304-100 (DGPS Base Station option is checked) Inside the box is a carrier board that has a power supply and an RS-232 TX/RX chip. The GPS board that plugs onto the carrier has a label on the underside that says VAR 100. This corresponds to the suffix of the part number on the box. The top side of the GPS board has the GPS receiver in a large metal box that is imbossed ALLSTAR 12 and CMC, which is the manufacturer (since then bought by Novatel?). Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tboltmon AMU range
Hi Russ AMU is a Trimble invented quality unit. I once heard a professor describe it as A Meaningless Unit. The Tbolt can change between AMU and dBc. With your range, the Tbolt has been switched to dBC, it is not showing AMUs. Approaching 50 with your high elevation SVs is excellent. You have a very good setup! If you wish to check it further, run Lady Heather with the Signal Strength vs Az/El plot enabled. http://www.ke5fx.com/heather/readme.htm http://www.mail-archive.com/time-nuts@febo.com/msg40567.html -- Björn I moved my Trimble bullet up the pole to have a 360 degree unobstructed view and now the AMUs for the SVs are reading in the 39-50 range. Is this too high or normal? Russ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Tbolt with Palisade?
On Sun, 2009-01-18 at 20:32 +, Grant Hodgson wrote: Does anybody know how difficult it would be to use just the antenna + LNA part of a Trimble Palisade? Have Tbolt but no antenna. I can get a Palisade for much less than a proper GPS antenna. Coax length would be about 20 feet, connected to the output of the Palisade's LNA (or output filter if fitted). Does the Palisade have an LNA at the antenna? Since it is an integrated receiver antenna construction, I would imagine they use a passive antenna. And you have no ready to use coaxial connector to the Palisade housing. Is it worth your time? Why not take a small mag-mount antenna (++many available at sub $10 at an online auction site close to you.) They usually have up to about 5 meters of thin coax (RG174 or equiv.). -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FTS 1000B OCXO from a FTS 4040 CS
Hi Stanley, On Sat, 2009-01-17 at 19:29 -0800, Stanley Reynolds wrote: Was unable to adjust to 5Mhz, 4.752 was the best I could get with external pot. Internal pot has no effect, assume it is disconnected when external is present ? Was not hard to dissemble, the oven is not warm but has 29 volts maybe problem in the control circuit. Does anyone have any info I could use ? I have downloaded a 4040B operation manual but it is not that similar to the 4040. This unit uses a 1802 RCA microprocessor so is much older than the B model, think it uses a 68xx type processor. I have no manuals for the FTS-4040 and been unable to connect a PC to the 9 pin monitor/sync connector on the back, I need the pin out and perhaps a older monitor program as I only have monitor 2 and monitor 3 programs. What I can see of the ocxo outside: Has 2 SMA RF out connectors and a 9 pin D connector inside: Oven was inside a glass vacuum bottle with layers of foam insulation to close one end. 2 MTH15N20 transistors to heat the oven temp sensor on a small separate pc board part #56219-03909 REV A attached to oven main board not insulated is part # 56219-06802-00 REV D There is some pinout information for 1000A and relatives in ftp://ftp.lysator.liu.se/~bg/time-nuts/FTS1200Doku.pdf I do not know if pinout applies to 1000B. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Free programs to read NEMA data.
Hi Warner, On Sat, 2009-01-17 at 16:30 -0700, M. Warner Losh wrote: In message: ca1.4beaaa2e.36a3c...@aol.com n3...@aol.com writes: : : OK I found my registration for NMEAT. Now that I upgraded my hobby PC I'm : giving it a work out by running as many applications as I can. I have NMEAT : running from a Jupiter GPS engine and I have T-Bolt mon going at the same time. : They are 16 seconds off from each other? I see on Tboltmon there is a field : for UTC offset and 15 seconds is entered there. Any ideas? The current UTC GPS offset is 16, and has been for the last 17 days or so :) That is not the view of USNO... ftp://tycho.usno.navy.mil/pub/gps/leapsecnanu.txt nor the Meinberg receiver I take care of. $ ntpq -c cv timehost.lysator.liu.se | grep gps_utc gps_utc_correction=current correction 15 sec, last correction on cd068600. Thu, Jan 1 2009 0:00:00.000, However I once had a Jupiter receiver where the NMEA output came 1.0xx seconds late or 2.0xx seconds late. Btw, the Jupiter/Zodiac binary was much better timed. Warner -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO TC
On Fri, 2009-01-09 at 10:28 +1300, Bruce Griffiths wrote: Richard Moore wrote: On Jan 8, 2009, at 2:58 AM, time-nuts-requ...@febo.com wrote: Message: 6 Date: Thu, 08 Jan 2009 11:51:50 +0100 From: Magnus Danielson mag...@rubidium.dyndns.org Subject: Re: [time-nuts] GPSDO time constant To: Tom Van Baak t...@leapsecond.com,Discussion of precise time and frequency measurement time-nuts@febo.com For ThunderBolt owners it is pretty straightforward to adjust the TC and damping, which is very nice. Use this oppertunity! So, Magnus (and Tom), what damping factor do you suggest for a TBolt? I'm running a verrry long TC now. If 1.2 is not actually critically damped, what value would be? Any guesses? BTW, I really like that plot of Tom's that tracks the oven and then gets better from the GPS... Dick Moore Richard As always, the problem is how do you know that the time constant you are using is anywhere near optimum? Bruce So what is optimum... from control theory we learn, that with an even better model of your system, you can push performance to the edge! But you always loose robustness in doing that. So what is the implication of a to large TC here? Nothing going instable in the control loop? We are just following the freerunning OCXO curve past the point where GPS goes downhill? -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO TC
On Fri, 2009-01-09 at 11:09 +1300, Bruce Griffiths wrote: [...snip... My point was that measurements are required to establish the optimum for each individual OCXO not just for a given OCXO model. Bruce Are those measurements possible to do in real time with only the GPSDO? -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Common sky pps errors for any GPSDOs?
Hi Matt, On Mon, 2009-01-05 at 22:03 -0800, Matt Ettus wrote: On Mon, Jan 5, 2009 at 9:27 PM, saidj...@aol.com wrote: Hi Matt, having 140ps matching of the 1PPS between units is the equivalent of knowing your antenna position to within ~0.14 feet total error max. Thats less than one inch error per antenna! That makes it sound a lot more difficult than it really is. The vast majority of the error in GPS is systematic, such that two GPS systems with antennas near each other should have highly correlated error. This is the basis of differential GPS. It doesn't matter if the absolute error is hundreds of feet, as long as both devices have the same error. One idea with a traditional GPSDO... I assume the sites have a real time communication link, Internet or Radio. Make sure the sites use exactly the same GPS SVs. This can be forced by telling the GPS to exclude SVs you do not want to use. Either you go with 1-SV timing mode and manually tell the receivers which SV to use. Or you juggle 4-6 SVs that are high on the sky on all sites. This will help the GPSDO to measure against the same satellites which gives you kind of a differential effect. I spent a couple of years nearly a decade ago doing differential GPS for steering heavy equipment. You can get sub-centimeter errors over baselines in the tens of km. Again, this is relative error. Sub 10cm, and even sub 5cm over distances up to 40km is possible with dual freq GPS receivers in real time. There are some reasonably priced dual freq GPS that can be driven by your external 5 or 10 MHz OCXO. The Novatel OEMV-2, beeing one candidate http://www.novatel.com/Documents/Papers/OEMV2.pdf Make one site the base and the others rovers. Pass RTK-corrections from your base to the rovers. You should get a very reasonable position errors, especially since your sites are stationary and you can let the RTK algorithms get plenty of time to converge. Then look at the receivers estimate of local oscillator drift for your frequency measurement. This is a fairly simple integration of COTS modules. Since the rovers are not taking advantage of beeing at a surveyed stationary position this is not the optimal solution. Someone on the list with the equipment and time to set this system up? Tvb, have you done this? Matt -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Deriving PPS from hockey-puck G-Mouse GPS receiver to lock an oscillator
On Tue, 2008-12-30 at 02:46 +1300, Steve Rooke wrote: [... even with the gusty winds we have been experiencing here. Now I have looked at the output of these which from a reset state run at 4800bd and produce the requisite NMEA 0183 protocol as expected. Looking at the TTL output on a scope there is a burst of data, at 4800bd, each second with a reasonable gap between each burst. Each packet of data starts with a $GPGGA message and time-stamping these shows they seem to occur at 1 second intervals. What I was thinking about building was a small circuit which would switch on the start of the data block and then time out at the end of the block thereby producing a 1Hz signal, albeit not 50% duty cycle, which could possibly be used to lock a ocxo via a phase-frequency detector, like a MC4044, and a low pass filter. Has anyone looked at this before and, perhaps discarded it or whatever? Yes, I know it is no substitute for a Thunderbolt but I don't have one of those yet and this may be a cheap and cheerful way to sync to GPS. Measuring is more fun than theoretical pondering... so start there. ;-) Try to measure the jitter on that 1Hz signal. Either with external hardware, or software. One way to do this is by configuring the GPS as a refclock to a computer running NTP. http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html When you have the computer running you can query NTP of what kind of jitter it sees. Look at the last column in the query below. With a few external network servers you can also estimate approximate delay or offset. Both are in milliseconds below. NOTE: The GENERIC clock here IS using PPS. $ ntpq -c pe timehost.lysator.liu.se remote refidst t when poll reach delay offset jitter == *GENERIC(0) .GPS. 0 l 64 64 3770.0000.001 0.002 +nissan.ifm.liu. .PPS. 1 u 644 1024 3770.655 -0.009 0.033 +ntp1.sth.netnod .PPS. 1 u 593 1024 3773.661 -0.037 0.053 +ntp2.gbg.netnod .PPS. 1 u 619 1024 377 10.967 -0.025 0.042 -ntp1.mmo.netnod .PPS. 1 u 623 1024 377 13.933 -0.097 0.050 Last time I tried a NMEA without PPS i got jitter of about 10ms. Delay (offset) was a few hundred ms. Why is NMEA probably the worst way to get time out of a generic GPS receiver? The receiver has more important stuff to do than putting the first bit of a long serial message on a slow 4800baud link exactly at the correct time. If the receiver is busy tending to its correlator chip. Serial output will have to wait. There are often two serial protocols implemented in the receiver. A binary format different for each manufacturer. Trimble has TSIP, SIRF Binary etc. This require less CPU to generate than the ascii NMEA. The binary protocol often has better timing. The number of CPU cycles to compute a PVT solution is not constant. With 4 satelite measurements its quicker than with 12 SVs in view. If the NMEA output is the task with lowest priority in the receiver the leading pulse timing accuracy will suffer. There are sometimes a short binary timing message that have better specifications on jitter and offset. This would probably be an order of magnitude better than NMEA. A real PPS would be another 3 or so magnitudes better. There are surely exceptions to the above arguments not to use straight NMEA. Measuring the performance over some time of cause gives you the best answer for your particular GPS. good luck! Björn Be gentle Bruce :-) 73, Steve ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] time-nuts Digest, Vol 53, Issue 46
On Thu, 2008-12-11 at 14:38 -0800, Brooke Clarke wrote: Hi Mark: I think it's out of date. The current method is to drop an optical corner cube (retro-reflector) in a vacuum and using a laser measure the distance it moves (which requires a reasonably good source of time. http://www.ngs.noaa.gov/GRD/GRAVITY/ABSG.html Have Fun, Brooke Clarke http://www.prc68.com Mark Sims wrote: The quintessential gravity meter (Worden Gravity Meter by Texas Instruments)... still being made after 60 years or so: http://www.mssu.edu/seg-vm/pict0246.html Spring based (relative) gravimeters are NOT yet dead... http://large.stanford.edu/courses/ph210/lee1/ and in local lingo for those so inclined... http://www.lantmateriet.se/templates/LMV_Page.aspx?id=4912 These are not _as_ good, but very mobile http://inertialsensor.com/qa3000.shtml -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] position determination over short distance
On Fri, 2008-12-05 at 09:49 -0800, WarrenS wrote: The way you are describing doing it may have one additional BIG problem you may not of addressed. The antennas must be smaller than 1mm or at least be stable in effective position to that accuracy. Good geodetic quality GPS antennas have well defined phase centers that are stable at the mm level. This is even though the antenna element might be the size of a small plate and the groundplane (chokering) is the size of a pizza. Above said, I would explore a digital camera solution for the OPs problem. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 10 MHz over optical fiber?
On Fri, 2008-11-28 at 02:50 +0100, Magnus Danielson wrote: Consider also things like laser gyroscopes. The stability of the fiber is sufficient to detect even small shifts frequency due to Sagnac effect. Usually called FOGs (Fiber Optic Gyroscope), where the other laser type, no fibers here, is called RLG (Ring Laser Gyroscope). -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] The Trimble NTPX26AB-06 / Z3801A
Hi Roy, On Sat, 2008-11-22 at 11:29 +, Roy Phillips wrote: at the front of the unit via a connector, and there is a location on this PCB for a for a 9-pin D connector!. If this had been used it would have made a serial port available at the front panel. More interesting is that there are tracks feeding what would have been pins 2,3 and 5 ! Perhaps there was an intention in the original specification to provide a service serial port to the front of the unit - but would this have provided RS-422 and not RS-232 signals ? RS-422 gives you, at least, RX+, RX-, TX+, TX-; your pins (2,3,5) cannot be RS-422. I would spy voltage levels with a scope, and hope for RS232-levels or TTL-levels. TTL is easily shifted with a MAX232 or equiv. Roy -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWV / WWVH / WWVB
On Thu, 2008-11-20 at 15:51 -0500, Brad Stockdale wrote: At 01:55 PM 11/20/2008, you wrote: I bought a nice little module from digi-key to handle this. 561-1014-ND, under $11 including the ferrite antenna. Interesting little module. Cheap too! Looking over the datasheet right now. Thanks for the pointer. Here is a euro-alternative that for a multitude of frequencies http://www.hkw-elektronik.de/englisch/products/assemblys.php I built a few receivers from this design http://www.buzzard.me.uk/jonathan/radioclock.html using HKW-modules. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oh the horror
On Mon, 2008-11-17 at 00:38 +1100, Jim Palfreyman wrote: Only this group will understand and suffer with this news... Our observatory has recently had three Russian hydrogen masers arrive (along with some Russians to install them). It turns out that one of the masers had a rough trip from Russia to Australia. It looks like the entire shipping case has been dropped or turned over from a reasonable height. The 7mm thick internal glass cylinder has been shattered and inside that the glass bulb has been smashed to bits. The whole unit is completely destroyed and useless. It's enough to make a grown man cry. On a much smaller scale... but the incident shown in the attached picture was no fun either... two old BVAs came the standard (brutal) post service packed like in the picture. One of the two got its glass bottle broken. :-( Thanks to lucky circumstances it later got repaired and a good new home. :-)) -- Björn attachment: bva_package.jpg___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP Z3801A Question
On Thu, 2008-11-13 at 05:44 -0500, [EMAIL PROTECTED] wrote: Hello, I am running the HP Z3801A after a long time again, more then 150hrs from the new ON status but I have never seen on the TI to GPS small window better figure then 1,5E-9. the avarage is 1,3E-8 and seldom goes to 10E-9. And running parallel the FURY board with a TEMEX OCXO and displays +1,6E-10 is the average very often 10E-11 and sometimes for a relative short time / 4-5 min / 1,4E-12. Are you comparing apples with apples? some nanoseconds error in _phase_ (time) seem reasonable (for the HP) . A _frequency_ error in the range of 1E-10 to 1E-12 is also reasonable (for the FURY). But then I have neither of the units you compare, so I could have misunderstood your issue. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP Z3801A Question
On Thu, 2008-11-13 at 10:14 -0500, [EMAIL PROTECTED] wrote: Hi Björn, According to HP spec sheet It should be better then just a few 1,5E10-9. Rgds Ernie. In phase or frequency? -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Checking the Frequency of a Rubidium Oscillator
On Tue, 2008-11-11 at 10:10 -0800, Hal Murray wrote: All the satellites are at the same frequency, and they are CDMA (each satellite has a different PN sequence on its signal) What's the bandwidth of an individual satellite? As said before. The carrier is chopped by a 1.023MHz PRN sequence on C/A and a 10.23MHz chipping rate on P(Y). -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Checking the Frequency of a Rubidium Oscillator
On Tue, 2008-11-11 at 10:28 -0800, Lux, James P wrote: A GPS receiver actually solves for the state vector of the receiver (including the local clock error) using the raw observables from the tracking loop (code phase). The nav equations calculate (apparent) range and range rate from the known state vector of each satellite and the (estimated) state vector of the receiver. Range rate is the doppler. The 1.xxx Megachip/second C/A code is 1023 bits long, so the classical approach is to step the receiver through all possible phases of the code, integrating at each one to see if it can detect the signal. If your integration time is, say, 10 milliseconds, it takes 10 seconds to step through them all. Once the signal is detected, the PN tracking loop tracks that signal. You also need to check different doppler bins. 500Hz bins are a classic choice. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
