Re: [time-nuts] 5V GPS antenna on 3.3V device?
On Tue, 10 Apr 2012 05:29:20 +0200, wrote: How's the best way to run an older 5V antenna with the new 3.3V GPS engines? Bias T? Assuming you want to open up and modify your GPS: In many GPS devices you'll find the biasing circuit easily just next to the antenna connector, built with discrete components. Sometimes you'll have to look in the datasheet of the GPS module, there will be a (often well accessible) pin to feed the bias voltage. Typical circuit: Antenna o--+-||---(GPS-Input-Amp) | | +---/\/\/\(Vcc) RF I-limit ChokeResistor Just lift up the I-limit resistor and feed in the suitable bias voltage to the RF choke. ___ 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] Synchronisizing a 100MHz TCXO with Tbold, pse help
Hi Tom, Christian Vogel : but of course: Whatever algorithms you put into your after-the-fact software correction will have an influence similar to a hardware PLL. Tom Van Baak : I'm curious about this. What are the inherent limits of each approach? One difference comes to mind -- with a software post-processing solution you get the benefit of being able to see samples in both the past and future. A hardware PLL works in real-time with data from the past. I have to admit that my comment was backed only by my "gut feeling" about how I would implement such a post-processing, which resembles a numerical PLL. But your question about a non-causal correction/filter/... is a very interesting one. I think it would be worthwhile to try and find it out experimentally: Setup a thunderbolt that receives the GPS signal but is undisciplined. Log both the internally measured PPS offset and the measured PPS versus a known good reference. Try to find the algorithm that gives the best estimate of the externally measured PPS offset from the internally measured (serial port logged) thunderbolt data. Greetings, 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.
Re: [time-nuts] Synchronisizing a 100MHz TCXO with Tbold, pse help
Hi Tom,
Would it be possible for your application to let the 100 MHz
TCXO free-run? Then you could use one or two of the ADC
channels to sample the TBolt 10 MHz and 1PPS leaving all
the rest of the channels to do real work.
This would then give you all the information you need to apply
phase adjustments to your ADC readings as an after-the-fact
software correction. Essentially you get all the benefits of GPS
time tagging and accurate reference frequency along with the
low jitter of your TCXO but without any of the additive noise of
a hardware PLL.
but of course: Whatever algorithms you put into your after-the-fact
software correction will have an influence similar to a hardware PLL.
{With the added benefit that you can improve your code at your
leisure and re-iterate without having to repeat your data recording.}
If one doesn't want to sacrifice an ADC channel to sample the reference,
I'd suggest going Chuck's route, divide the 100 MHz down to 10 and let
the thunderbolt discipline the 100 MHz TCXO.
But when business gets serious, you can break the loop and put the
Thunderbolt into holdover manually. It will then keep the control input
of the 100 MHz stable but will still measure the phase and frequency
offset with respect to GPS time. You could then use the data recorded
from the thunderbolt to do phase corrections on your sampled data as
suggested.
Chris
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Re: [time-nuts] Does TB keep almanac data ?
Hi Alberto, Why almanac data are not kept ? Not enough space in that non volatile memory ? the thunderbolt is meant for permanent installation in mobile base stations where power outages are pretty rare, so I guess the designers didn't see it worthwhile. 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.
Re: [time-nuts] What are these towers?
Hi Jim, On Sat, May 21, 2011 at 06:56:24AM -0700, Jim Lux wrote: > there *is* a sort of tangential connection. One of the more interesting > strategies in broadcasting these days is forming coverage areas with > arrays of geographically dispersed transmitters, all synchronized well > enough that the signals received from all transmitters are appropriately > synced. I live just adjacent to a DVB-T transmission tower, and I've visited the premises: In case of south-german DVB-T I can confirm that they have Meinberg GPS receivers for synchronizing. > I think this is being done with DVB-T in europe, maybe someone will comment? It is being done like that in DVB-T. The interesting thing to realize is that you *will* have signal cancellations inevitably for some frequencies depending on your position with respect to the synchronized transmitters, and you'll have to choose a modulation that can deal with this selective fading of subcarriers. If you also want to be resilient to errors introduced by multipath-reflections, you'll end up at OFDM which modulates *many* carriers (typically 7000 or so) at a rather low symbol rate. Then if some of the carriers get mangled, the forward-error-correction will take care. Highly fascinating, but most likely completely un-time-nutty :-) 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.
Re: [time-nuts] USB and Mouse conflict persists
Hi Stan, I am running XP Pro with a USB laser mouse and a USB to serial adapter to the T'Bolt. The USB to serial adapter drivers are on hand and they loaded nicely, with the computer setting the USB port to COM10. if your adapter uses one of the popular FT232 chips from FTDI, then your "mouse" will be rediscovered from time to time, thanks for the "Serial Enumerator" feature present in the driver (see http://www.ftdichip.com/Documents/AppNotes/AN_107_AdvancedDriverOptions_AN_73.pdf ). To disable this incredibly frustrating function, open the windows device manager and remove the serial mouse. Then open the properties of the serial COM port. On the tab "Port Settings" click "Advanced" and in that window uncheck the box next to "Serial Enumerator". http://lh5.ggpht.com/_zKkNaqX3vkM/S-mRNIaXuoI/Aw8/W6mWXYShUC8/s1600-h/serial-properties%5B2%5D.png You'll have to repeat this whenever your USB-to-serial adapter is re-discovered, for example when you've moved it to a different USB port on your machine. Greetings, 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.
Re: [time-nuts] 60hz disciplined watch
Hi Poul-Henning,
On Wed, 20 Apr 2011 17:26:15 +0200, Poul-Henning Kamp
wrote:
In message , paul
swed writ es:
...
As for mains stability. They are indeed stable over time weeks and
months
and are corrected.
...
Here in europe that was lost in the "privatization" of the grid: Nobody
was charged with paying for the extra power needed to capture lost
cycles, so now they just try to keep it close to 50.0Hz and don't
care about the integral.
where do you get that information? The ETSOE(transmission operators
network)-handbook
which specifies the control-loops for frequency/phase have a section on
TIME CONTROL.
They define different levels of allowed offsets between integrated network
phase and UTC.
There are three bands with allowed deviations of +/- 20, 30 and 60 seconds
(target, tolerated and exceptional).
https://www.entsoe.eu/resources/publications/entso-e/operation-handbook/
--- QUOTE from Section P1, Page 29 ---
D. Time Control
[UCTE Operation Handbook Appendix 1 Chapter D: Time Control, 2004] {update
under preparation}
Introduction
The objective of TIME CONTROL is to monitor and limit discrepancies
observed between
SYNCHRONOUS TIME and universal co-ordinated time (UTC) in the SYNCHRONOUS
AREA.
Reasonably it is applied during periods of uninterrupted interconnected
operation, where the
SYNCHRONOUS TIME is the same in all control areas.
...
A discrepancy between SYNCHRONOUS TIME and UTC is tolerated within a range
of ±20 seconds (without need for time control actions).
---/QUOTE---
Greetings from Germany,
Chris
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Re: [time-nuts] Linux timekeeping / jiffy source
Hi bownes, Unfortunately, there is no way to restart the kernel without going through a BIOS re initialization. actually, there is. It's called "kexec". See, for example http://www.ibm.com/developerworks/linux/library/l-kexec.html . Greetings from Germany, 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.
Re: [time-nuts] Galvanic decoupling of GPS antenna
Hi Yuri, I'm trying to put gps (for a coarse timing sync and RTC auto-setting) to a small controller that must be completely galvanically decoupled from outside world. Antenna power must be supplied from separate power source (ground potential of isolated part of circuit can slowly float up to +/- 250 volts referenced to ground of antenna power supply). I don't see any need for isolation in the signal chain as long as your antenna and cable are properly insulated. I have a fully sealed antenna here on a Thunderbolt and nothing -with exception of the BNC connector at the cable end- exposes the system ground. So I could easily float the TBolt and connected PC at +250V without anyone "outside" noticing. 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] Serial Port Redirection Recommendation: com0com, com2tcp & hub4com
Hi, to add a few cents to the discussion about Lady Heather's Client, I want to recommend the following piece of software to the windows-using 'nuts: http://com0com.sourceforge.net/ This is a driver that provides for mutually connected virtual serial ports under MS-Windows (I'm right now using it with Win7, x86) and there are two additional programs: com2tcp and hub4com. Com2tcp connects a serial port (hardware or virtual) to a tcp-connection, either as a server or as a client. hub4com allows more complicated routing of serial-port data. With these tools, you can probably implement a lot of the "several programs listening to a single gps" scenarios already and can of course used whenever some old serially connected equipment has to be talked to over the network. The attached screenshot is from my Windows-7 Desktop, where Tboltmon talks to a Thunderbolt hanging on a Linux machine that has a small TSIP-Multiplexer running I wrote with Twisted [http://twistedmatrix.com/trac/]. The upper left shows com2tcp that connected to the Linux machine, the lower left is the com0com configuration program and behind there's the well known Thunderbolt Monitor from Trimble. Of course, it also works with Lady Heather. Once again using ASCII art in case my explanation above was a little confusing: +Linux-+ +-+ | | | Thunderbolt o-(RS232)-o ttyS0 --(Twisted)-- TCP:8000 | +-+ | || +-o+ | =o==o= (Ethernet) | +---oWindows+ | | +-+ | |com2tcp -- COM3 ---o com | | | | 0 | | | tboltmon -- COM2 ---o com | | | +-+ | +---+ I hope the ASCII Art comes through fine. 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] Alternate frequency sources : DVB-T and ISDN?
Hi Alan, I cant remember the detail now but my converstaion with a BBC engineer at the NPL meeting a few years back suggested along the lines of "yes there would be a stable frequency available on a digital TV signal but no it would not be related (tracable) to any given standard because it didnt need to be." at least here in Germany the digital TV transmissions (DVB-T) are using (in some areas) Single Frequency Networks[1]. I live near one of the transmitters and when I visited the facility, they had Meinberg GPS receivers in the racks housing the TV signal generators. Speaking of alternate sources: Has any time-nut considered using the ISDN telephone network [2]? Chris [1] http://en.wikipedia.org/wiki/Single-frequency_network [2] http://openbsc.gnumonks.org/trac/wiki/isdnsync ___ 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] ad-hoc I/O
Hi Rick, The other problem I have with these kinds of devices is what to do about software to talk to them. ... The tutorials assume the program talks only to the "console" (keyboard mouse and monitor). No discussion of connecting to the LAN and interfacing with the hardware. What I have seen written about these topics is incomprehensible to me as an analog engineer. what I say now might make me sound like a pleistocene fossil, but you might want to have a look at TCL/TK (http://tcl.tk/). I used it in the past to talk to network servers mostly, but also have used it to talk to serial peripherals. There are extensions (BLT) to draw graphs built in. Hello World (Button that says "Hello World" and closes the application): : http://wiki.tcl.tk/488 Serial Port Logic Analyzer Screen Capture (first hit in the Wiki for "serial port"...) : http://wiki.tcl.tk/13583 (note that the last example could be adapted to a network-coupled serial port by changing the "open" to a "socket"-call) There's plenty more, tcl/tk is a real unix dinosaur (not something for the hip Ruby-on-Rails folks...) 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] ad-hoc I/O
Hi Dave, Likewise, there are also versions of MCU's with TCP stacks available too, as well as things like this... http://www.lantronix.com/device-networking/embedded-device-servers/xport.html ... Basically, an embedded TCP/IP<>Serial adapter, with bells on! So you can use existing device designs that would use a serial link to the host, and "add" network connectivity for that need, with no (well, little) design overhead. When I was looking for something simmilar, a relative recommended http://www.ak-nord.de/ak/product_info.php?products_id=33 which he uses at work to access interfaces internal to their product during testing. It should be what the "xport" is, but adding i2c and spi ports. Unfortunately, I didn't find time to procure one, or even test it. 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.
Re: [time-nuts] Using cheap sound cards for measurements
Hi Lux, Syncing inexpensive cards is a real chore (and the only reason to be thinking about using this in the first place is to keep the cost to a minimum, otherwise, you might as well build a special purpose little box with counters & A/Ds, and an interface) I've had too many problems with cheap (onboard) soundcards in the past, even when using them for their intended purpose, so I would not advice to use them for anything quantitative. But if you *really* want to syncronize inexpensive soundcards, it's rather trivial, see for example http://quicktoots.linuxaudio.org/toots/el-cheapo/ . Just buy a few dozens for a EUR/$ each and hunt down the ones with identical oscillator frequencies ;-). But don't expect miracles, you end up with a few synchronized cards that only happen to not skip samples with respect to each other. Compared to decent signal input they are still cheap cards, and hog the CPU for their individual servicing. 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.
Re: [time-nuts] Obscure terms
Hi Rex, Yep, as usual Google is fantastic for this task. Asking, 'RCH definition', I found out this: Royal Canadian Hussars ... try the "urban dictionary", it's a very good reference for slang terms, not safe for work for some, though... http://www.urbandictionary.com/define.php?term=rph 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.
Re: [time-nuts] Multiple Voltage monitoring
Hi Bill, I was going to suggest, depending upon Matts interests, that perhaps he could use a PIC or ATMEL device with analog inputs and roll his own. Most PIC models have 10 bits but some do have 12 bit. You could use an external A/D for 12 bits or more. I actually used this for a laboratory setup just recently, but I only needed about 1% of accuracy. I bought a "Arduino Duemilanove" board for *?25*. This includes a FDTI USB-to-serial and a Atmel AVR microcontroller and is powered from USB. Their simple IDE speaks a preprocessed version of C and it took me 5 minutes to have my 3-channel-analog-to-serial software done. You can also use your conventional toolchain and just ignore their beginners' environment, though. http://arduino.cc/en/Main/ArduinoBoardDuemilanove 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.
Re: [time-nuts] looking for good description/generalized model for time adjustments
Hi Lux,
The real problem is that the "master" clock might be a crummy 50ppm XO, and all us
"slaves" all have TCXOs that are good to a few ppm. It's almost the inverse problem from
disciplining a XO with GPS.
I have the impression that you are confused by your own weird
terminology ;-). If you have a rather good clock yourself, and want to
somehow characterize external events with their own sketchy time-of-day
estimation, then please don't call this cheap thing the "master".
Just let your internal clock ("precise") run undisturbed and capture the
precise time for all the external events received from the "cheap"
outside machines. Then timestamp a number of external/internal events
and calculate the average relative external clock frequency. Filter the
last N events and use the relative frequencies to extrapolate events to
be expected in the future. It's basically just a PLL done in software.
Without telling us some details, noone here will be able to give you
real advice, I think...
Chris
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Re: [time-nuts] Cabling GPS antennas
Hi Steve, > these frequencies. I was thinking outside the square and see that > dual/quad screened RG6 is cheap and plentiful now but of course it's > 75Ohm and there would be a big fat impedance mismatch using this. I > thought about looking at fitting impedance matching baluns at each end > but that is not cheap and there are losses involved with this approach > anyway. the manual of the Trimble Thunderbolt GPSDO recommends doing exactly that. 75Ohm cable obviously is cheaper, due to it being ubiquitously used for TV and video installations and has lower loss due to the higher impedance (impedance/resistance ratio). They (Trimble) claim that reflections will not introduce any problems. One can argue that, to cause interference effects, a wave has to travel back from the GPSO to the antenna and back to the GPDO (where it interferes with the direct signal). This will be attenuated by the SWR twice, and dampened by the cable loss twice. The issue at hand has been discussed at length one (two?) year(s) ago and included a link to an article that analytically analyzed the effect of multipath (of which the reflections are a specific case) on GPS accurady, if I remember correctly. Chris --- Quote from the Trimble manual (ThunderboltBook2003.pdf), Page "3-5" --- Note ? RG-59 is a 75 ohm coaxial cable. The ThunderBolt and the Bullet antenna are compatible with either 50-ohm or 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. Note ? The input impedance of the ThunderBolt RF input & its antenna is 50 ohms. ___ 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
Hi Hal, > What's the bandwidth of an individual satellite? the bandwidth is defined by the ~ 1 MHz "chipping" rate that phase-modulates the carrier, so it's roughly 1 MHz to both sides of the carrier (for the civilian signal). Search google images for "gps spectrum" to see plots... :-) 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.
Re: [time-nuts] Thunderbolt and USB to RS232 converters
Hi Bob, > A tip for anyone that might be designing software. Don't put a fixed limit > on the USB virtual COM ports like 1 to 16. Make a pull down that show > what ports are really populated via the SetupDI API. The next new USB > COM port I plug into my development machine is going to be assigned > COM44! > > Anyone know where in the registry to reset the ever incrementing > new COM number? > Control-Panel -> System -> Tab: Hardware -> Device Manager In the device manager, choose "View: Show hidden devices." The grayed out devices have once been, but are no longer, connected to your machine. Remove the ones that you no longer care about. You can also remap the comport-numbers in the properties of the serial port devices, use the button "Advanced..." there. These are the things that make me happy to be using Linux for most of my electronics stuff ;-)... 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.
Re: [time-nuts] Rb references for audiophiles?
> ESOTERIC - G-0Rb MASTER CLOCK GENERATOR (RUBIDIUM) …“esoteric”… While I realize the absurdity of hooking up such a thing to your CD player at home, there can be merits of having a centrally generated and extremely accurate clock in a professional audio/video production facility. When you are passing around digital audio and video signals between production desks in different rooms or even countries, missing drift can eliminate the need for special resampling equipment (frame stores for video). > which oddly, is actually made by a division of Teac > http://www.teac.com/esoteric/ > http://www.teac.com/esoteric/Master-Clock_Up-Converter.html > There's also this: > http://forum.cakewalk.com/tm.asp?m=1304280 …that's proably also where it originates at TEAC, my guess is that they modified a professional device to fit into the audiophile market. > Fascinating, too, that they don't actually have any real data on the > jitter performance of their box on the spec sheet.. even though that's > what they're selling.. they just quote the absolute frequency accuracy. I'd say you don't get the concept of “Audiophile Equipment” here! :-) It doesn't matter what the measurement says as long as you can hear it, the sound is more vivid and… you get the idea. Chris (who get's his 48kHz wordclock by dividing 18.4 MHz from a can oscillator by 348 with a AVR microcontroller…) ___ 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] THUNDERBOLE STATUS LED'S
Hello Jeff, > Has anyone determined how an interface could be incorporated into the > Thunderbolt so as to show if it was locked. Some status led's would be nice > such as can be fount on the Z3801's front panel. provided that there is no easily accessible connector with the relevant signals inside the Thunderbolt, the easiest thing would be a microcontroller circuit listening to the serial data on the 9pin DSUB port. About any microcontroller with the power to process the data at 9600 bps will be fine, which includes pretty much every AVR, PIC, 8051, MSP,… currently available. I was pondering about that myself, but unfortunately will be quite busy for the following month… ☹ 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.
Re: [time-nuts] thunderbolt for ntpd or gpsd
Hi Tim, On Thu, Jun 12, 2008 at 10:05:13PM -0400, Tim Cwik wrote: > Is there a way to have gpsd use 8N1 for TSIP? The manual says teh > thunderbolt uses 8N1, the windows support program says it and the > thunderbolt are using 8N1. I can not find a way to tell the thunderbolt > to use 8O1. as a quick hack, use the following command just after you started gpsd to force the parity to non on the serial line: [EMAIL PROTECTED] ~ # gpsd -n /dev/ttyUSB0 [EMAIL PROTECTED] ~ # stty -F /dev/ttyUSB0 -parenb -parodd When in debug-mode, gpsd then spits out the following lines: gpsd: Software version: 3.0 020627 10.2 04 gpsd: GPS Time 485697.156250 1483 14.00 gpsd: Current Datum 0 0.00 0.00 0.00 6378137.00 0.006694 gpsd: Navigation Configuration 3 7 0 4 0.00 0.00 0.00 -0.93 0 gpsd: GPS Time 485697.25 1483 14.00 gpsd: Sat info: mode 1, satellites used 5: 18 9 28 15 26 gpsd: Sat info: DOP P=0.0 H=0.0 V=0.0 T=1.0 G=1.0 gpsd: Satellite Tracking Status: Ch 0 PRN 10 Res 0 Acq 1 Eph 2 SNR 2.8 LMT 485697.2500 El 10.0 Az 191.7 gpsd: Satellite Tracking Status: Ch 1 PRN 18 Res 0 Acq 1 Eph 2 SNR 20.2 LMT 485697.2500 El 25.9 Az 307.3 gpsd: Satellite Tracking Status: Ch 2 PRN 9 Res 0 Acq 1 Eph 2 SNR 21.6 LMT 485697.2500 El 25.5 Az 272.1 gpsd: Satellite Tracking Status: Ch 3 PRN 17 Res 0 Acq 2 Eph 0 SNR 0.0 LMT 485697.2500 El 23.8 Az 123.5 gpsd: Satellite Tracking Status: Ch 4 PRN 28 Res 0 Acq 1 Eph 2 SNR 5.0 LMT 485697.2500 El 54.4 Az 65.0 gpsd: Satellite Tracking Status: Ch 5 PRN 15 Res 0 Acq 1 Eph 2 SNR 12.0 LMT 485697.2500 El 77.5 Az 260.3 gpsd: Satellite Tracking Status: Ch 6 PRN 8 Res 0 Acq 2 Eph 2 SNR 1.2 LMT 485697.2500 El 16.9 Az 78.8 gpsd: Satellite Tracking Status: Ch 7 PRN 26 Res 0 Acq 1 Eph 2 SNR 7.8 LMT 485697.2500 El 78.8 Az 161.7 gpsd: Unhandled TSIP superpacket type 0xab Unfortunately, it does not show any information about time or position on a connected cgps/xgps client. 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] Progin GPS Antenna
Hi, I acquired a GPS antenna for use with a Trimble Thunderbolt (which provides +5V antenna supply voltage) on ebay.de this week (seller "gps-laden"). While initially the seller cited compatibility with 3.3-5V GPS receivers, the actual unit shipped has a label reading "2.7-4.0V", which matches what the manufacturer (http://www.progin.com.tw/Active_Antenna_en.htm : 3.3V +/- 0.6V) puts on his webpage. After further inquiry, "gps-laden" now claims Progin had assured that the antennae would work also with the higher supply voltage, but he will not guarantee it, he had offered to take back the antenna, though. So the purpose of this email to time-nuts is twofold :-)... (1) if you live in germany and are looking for a little GPS antenna for your disciplined clock, the prominent search result on ebay might not be what you want, even if you ask specifically and... (2) my question to the group: Does anyone use a Progin antenna sucesesully 20% outside of the specified voltage range? (I would hate to wait another week for my antenna...) Greetings from Germany, 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.
Re: [time-nuts] RS485/422/232 Chip
Hi Bruce, >> The MAXIM MAX3162E will do RS485/422 and RS232 in the one chip , get >> samples from maxim.com. >> > These devices only implement a single RS485/RS422 transmitter and receiver. > That's true for the 3160 which can be switched between two RX and two TX of RS232 or one RX and one TX of RS485. The 3162 does both functions simultaneously. I had a look at the MAX3535E recently, which has a isolated RS485 transceiver with capacitive coupling in it, did anyone of you use those to break ground-loops? I'm especially interested if this kind of "capacitor-isolation barrier" adds any significant noise to the RS485 lines, which might couple into sensitive signals running in parallel, or if I should just go the traditional optocoupler-route. Greetings from Germany, 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.
Re: [time-nuts] sync computer clock ticks
I forgot two things! (1) It's all Linux, with stock kernel.org kernels, see below. (2) see comment about the application below. Christian Vogel schrieb: > at work, I use it to sync all servers and workstations to 4 stratum 1 > NTP-servers. I get ~100us offset usually. Without special hardware I'd > say that 1usec is not possible. > > Server, Gig-Ethernet, 4 hops (>=Gigabit) to ntp: > *ntp2-rz.rrze.un .GPS. 1 u 758 1024 377 1.225 **-0.179** 0.068 > (HP DL380-G3, Dual 3.2 GHz P4, no powersaving) > -> Temperature fluctuates +/- 3 Deg-Celsius every 20sec due to HVAC Kernel 2.6.21.3 SMP > > Client, 100Mbit, 5 hops (last 4 are better than Gigabit): > *ntp2-rz.rrze.un .GPS. 1 u 987 1024 377 1.577 **-0.111** 0.091 > (P4-Celeron, 2.4 GHz, currently throttled to 300 MHz) > -> Temperature currently stable and possibly very cool, have not > been in my office for a week :-) Kernel 2.6.22.1 PREEMP And: We should not forget the original poster's question about if 1 usec precision can be achieved? I'd say that the most important thing about this question is, what application the precision is needed for. For example, do you want to timestamp interrupts to synchronize machinery? Or just note down the timestamps of bittorrent downloads very precisely? Just synchronizing an otherwise idling computer is probably much easier than a machine that is doing a lot of additional work that can mess up the timekeeping by clogging the processor or just creating varying stress on the power-supply lines. Scatterbrained, 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.
Re: [time-nuts] sync computer clock ticks
Hi Michael, > I've used NTP for years, but i was under the impression that it is not > able to synchonize the clocks below 1 or 2 seconds. Can you point me > towards a specific article that speaks about the configuration > parameters to get ntp sync'd that low? at work, I use it to sync all servers and workstations to 4 stratum 1 NTP-servers. I get ~100us offset usually. Without special hardware I'd say that 1usec is not possible. Server, Gig-Ethernet, 4 hops (>=Gigabit) to ntp: *ntp2-rz.rrze.un .GPS. 1 u 758 1024 377 1.225 **-0.179** 0.068 (HP DL380-G3, Dual 3.2 GHz P4, no powersaving) -> Temperature fluctuates +/- 3 Deg-Celsius every 20sec due to HVAC Client, 100Mbit, 5 hops (last 4 are better than Gigabit): *ntp2-rz.rrze.un .GPS. 1 u 987 1024 377 1.577 **-0.111** 0.091 (P4-Celeron, 2.4 GHz, currently throttled to 300 MHz) -> Temperature currently stable and possibly very cool, have not been in my office for a week :-) My main problem is probably that ntp switches between three equally good servers quite frequently (it just did). 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.
Re: [time-nuts] CPU frequency and NTP crazyness.
Hi Ryan, > maximum speed and everything has been just peachy with NTP. My > question is this, does anyone have a way to switch off the power save > feature the CPU is using so I don't have to run my machine full tilt? you can do it by changing different power-schemes in Windows' Control-Panel Power Properties. Download RMclock to watch your CPUs clocks and voltage/frequency settings while playing with the power-schemes. If you select "Always On", your computer will not do any power-saving. 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] Scrambled Messages {EZGPIB & other software}
); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY Executive summary: ^--- these two lines are to blame :-) ---^ Hi everyone, the problem is with the superfluous "SAEximRunCond"-lines. Ulrich's mailer chose to encode the Email-message in Base64, so the message is supposed to look like this: > From: "Ulrich Bangert" <[EMAIL PROTECTED]> > To: "Time nuts" > Subject: [time-nuts] EZGPIB & other software > Content-Type: text/plain; charset="windows-1251" > Content-Transfer-Encoding: base64 > > SGkgZm9sa3MsCgp0aGlzIGlzIHRvIGlu... (<-- this is base64 of "Hi folks,...") Now between Content-Transfer-Encoding and "SGkg..." the well-known bug we witness on this list will insert the two lines starting with "SAEximRUnCond...". A mail-client then tries to base64-decode this, which in my case will make Ulrichs Email start with some interesting looking cyrillic characters. As it's not the usual base64, I expect mail-clients to behave strange... Without the two erroneous lines, I see no problem with Ulrichs emails. I hope, I could clarify a little... 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.
Re: [time-nuts] DCF77 signal change
Hi Everyone, Poul-Henning wrote: >> Anyone know the encoding of the weather info ? I wonder if they >> use the minute bits to designate regions to save bits ? >> >> This PDF is written in german, it contains the following Paragraph: (http://www.hkw-elektronik.de/pdf/DB%20W-Protokoll-V%201.pdf) """Die übertragenen Daten können nur mit der über den Lizenzvertrag beschaffbaren Dechiffriervarianten geprüft und für die Auswertung bzw. Anzeige nutzbar gemacht werden""" --> The transmitted data can only be used using the deciphering-methods availabe via license... Their homepage also states further that to decipher the data one has to be a licensee of Meteotime. With greetings from Germany, Chris ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] DCF77 signal change
Hi Poul-Henning, > Anyone know the encoding of the weather info ? I wonder if they > use the minute bits to designate regions to save bits ? > http://www.ptb.de/en/org/4/44/442/dcf77_kode_e.htm : "In addition weather data are transmitted, which are supplied by the Swiss firm Meteo Time GmbH. The same data are transmitted also by the Swiss standard frequency and time signal service HBG (75 kHz)." HBG claims to be quite DCF77 compatible with their modulation, so hope is that it's actually the same encoding. I did not find any info about how they encode the information, though :-( Chris ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Coax switch
Hi Richard, > DPDT ?? > double pole, double throw, which could be drawn like this: -o -o o -(pole 1) -o -o o -(pole 2) ^ | Two "throws" each. Chris ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Serial Port Logging Script?
Hi everyone,
I have been lurking for quite some time, so let me use this
opportunity to say hello to everyone.
Regarding logging serial port-data to files, there is always
trusty old tcl. It should be installed on almost every Solaris,
HPUX, AIX, Linux, Freebsd, ... machine there is.
I used the "extended" version below to read out a Hameg-8123
counter over a period of several weeks, it worked flawlessly.
The "reduced" version will just print out all lines it receives,
prefixed with a human-readable and a unix-since-epoch timestamp.
21:15:35 1166818535 FRA 9.84604 MHz
21:16:42 1166818602 FRB 9.98405 MHz
21:17:48 1166818668 RAB 0.98619
21:18:55 1166818735 FRA 9.84597 MHz
Greetings from Germany,
Chris
- snip (reduced version) -
#!/usr/bin/tclsh8.4
# callback when there is reable data on the serial port
proc getData { chan } {
if { [eof $chan] } {
return
}
# get one line from serial port
set s [gets $chan]
# form timestamp
set t [clock seconds]
set f [clock format $t -format "%H:%M:%S"]
# print timestamp
puts "$f $t $s"
}
set sp [ open "/dev/ttyS0" "r+" ]
fconfigure $sp -blocking 0 -mode "9600,n,8,1" -handshake none -buffering
line
fileevent $sp readable [ list getData $sp ]
set quit 0
while { $quit == 0 } {
vwait quit
}
- full script
#!/usr/bin/tclsh8.4
set currchan ""
proc getData { chan } {
global currchan
if { [eof $chan] } {
return
}
# get one line from serial port
set s [gets $chan]
# puts "chan << $s"
# check if it looks like a number (starts with 0-9)
# if there is no recent measurement, the counter will
# respond with "Not available" or such.
if { ! [string match "\[0-9.\]*" $s ] } {
return
}
# form header
set t [clock seconds]
set f [clock format $t -format "%H:%M:%S"]
# print timestamp, unix seconds, string from counter
if { "" != "$currchan" } {
puts "$f $t $currchan $s"
}
# Advance channel.
switch $currchan {
FRA { set currchan "FRB" }
FRB { set currchan "RAB" }
default { set currchan "FRA" }
}
puts $chan "$currchan"
}
# send "XMT" to counter, which tells the counter to return
# the most recent measurement
proc doTick { chan } {
puts $chan "XMT"
after 1000 [ list doTick $chan ]
}
set sp [ open "/dev/ttyS0" "r+" ]
fconfigure $sp -blocking 0 -mode "9600,n,8,1" -handshake none -buffering
line
fileevent $sp readable [ list getData $sp ]
# input channel A AC, 50 Ohm, 1:10
puts $sp "ACA"
puts $sp "OAL"
puts $sp "LVA0.00"
puts $sp "AA1"
# input channel B
puts $sp "ACB"
puts $sp "OBL"
puts $sp "LVB0.00"
puts $sp "AB1"
# gate time: 65535 ms
puts $sp "SMT65535"
# poll counter every 1000 ms
after 1000 [ list doTick $sp ]
set quit 0
while { $quit == 0 } {
vwait quit
}
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