[time-nuts] VNG in a Box
My ears are burning... was someone talking about one of my projects? VNG in a Box is a fairly old project by now, although the design and code are still available. Essentially it's 'payware', so while not entirely open source, you can get to own the source code for very little. If anyone has questions about the project, just send me an email. By the way, if you're looking for a good homebrew GPS Reference (VNG in a Box is a lot more than that), try my Simple GPSDO: http://www.qsl.net/zl1bpu/MICRO/SIMPLE/SimpleGPS.htm 73, Murray Greenman ZL1BPU ___ 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] Z38XX PFORTH interpreter question
Hi, Has anyone made further progress in understanding the PFORTH commands? I find with my Z3815A (with an E1938A hockey puck oscillator installed) that the command 'puck' returns: a= -6.305066e-13 b= 0.00e00 a/d = 1.60e+01 puck communication is alive puck warm= 1 puck EFC ADC err= 0 status1 byte= 1 status2 byte= 0 What fun! I wonder what the three variables are and can one change them? As a separate but related question, I've just swapped out a failed MTI 260 OCXO from this Z3815A and fitted in its place the older E1938A hockey puck. The problem I have is that the EFC sense seems to be reversed. Does anyone know how to change this, either by sending a PFORTH command or otherwise? It would be great to get the Z3815A going again. 73, Murray ZL1BPU ___ 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] Changing FE-56XX frequency
As Bill suggests, the best way to achieve any-frequency performance with the newer FE-56xx devices is to pull out the Rb reference frequency and run an external DDS off it. I found that the Rb loop frequency in the one I played with was exactly 60MHz, rather than the 50.255MHz of the older units, although it doesn't really matter what it is. I run mine with an AD9852 in x4 mode (so the clock is 240MHz), and so have a range of 0 - 90MHz. The only control software I have at present is the dreadful parallel port program which came with the AD development kit, so it is useful only as a signal generator. One day I'll write it something better. 73, Murray ZL1BPU - Original Message - From: To: Sent: Tuesday, April 09, 2013 4:00 AM Subject: time-nuts Digest, Vol 105, Issue 22 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than "Re: Contents of time-nuts digest..." Today's Topics: 1. Re: Changing FE-5650A frequency? (Don Latham) 2. Re: Trimble SVeeSix -- was DATUM 9390-52054 Grief again... (Brooke Clarke) 3. Re: Changing FE-5650A frequency? (WB6BNQ) 4. Re: Lady Heather (Achim Vollhardt) -- Message: 1 Date: Sun, 7 Apr 2013 15:29:46 -0600 (MDT) From: "Don Latham" To: "Discussion of precise time and frequency measurement" Subject: Re: [time-nuts] Changing FE-5650A frequency? Message-ID: <1e9644594b69bd93447cb42b0d60444d.squir...@webmail.montana.com> Content-Type: text/plain;charset=iso-8859-1 wow, a little more picking will get you to the dds pinout wrt the 24-bit programming word... Alexander Wright On 07/04/13 15:10, Herbert Poetzl wrote: The purpose of the polymer foam is isolation to keep a stable temperature throughout the boards. http://www.qsl.net/z/zl1bpu/PROJ/FE5650-2.jpg The top layer in this image is the DDS board, and it is basically identical to the FE5680A, which means it can be adjusted in a wide range, but only does digital synthesis based on the reference frequency. But let's see what Bill says to the pictures ... :) best, Herbert Herbert, the board doesn't seem to be the same, the chips which are visible don't line up with the ones in that picture. Anyway my curiosity got the better of me and I dug through the foam some more to find a long row of DIP switches. I bet i can change the divider ratio with some combination of those: http://m0tei.co.uk/fe5650pics/IMG_20130407_170929.jpg Also, you can see that the chip is an AD9955 DDS chip: http://novatech-instr.com/PDF_files/AD9955.pdf - Alec ___ 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. -- "Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind." De Erroribus Medicorum, R. Bacon, 13th century. "If you don't know what it is, don't poke it." Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.com -- Message: 2 Date: Sun, 07 Apr 2013 15:21:58 -0700 From: Brooke Clarke To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Trimble SVeeSix -- was DATUM 9390-52054 Grief again... Message-ID: <5161f186.9000...@pacific.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Hi: I spent a lot of time with the SV6 learning about GPS. http://www.prc68.com/I/Trimpack.shtml#SV6 Note: The Trimpack web page has a bunch of Trimble GPS receivers, not just Trimpacks. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html -- Message: 3 Date: Sun, 07 Apr 2013 13:55:13 -0700 From: WB6BNQ To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Changing FE-5650A frequency? Message-ID: <5161dd31.1ab6...@cox.net> Content-Type: text/plain; charset=us-ascii Hi Alec, I am going to agree with Robert (G8RPI) on his assessment, particularly as the dip switches are clearly visible in one of the pictures. Although I wonder why Robert feels unfortunate about the [ two chip DDS arrangement ] ? It matters not the number of chips that make up the DDS. Why ? Because the actual physics package and its electronics has nothing to do with the DDS in the older designs. That is, the signal output of the physics package is a fixed frequency (around 50.255 MHz) that yo
[time-nuts] Open source
My mistake was inferring that my GPSDO software was open source. It's absolutely not. It is proprietary to me and written in AVR assembler. There is no reference anywhere in it to any libraries from any other source. So don't get too excited. You can still see what's inside it for $50, but you need to be able to understand AVR assembler source code. 73, Murray ZL1BPU ___ 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] Open source GPSDO
Keenan, You can see my GPSDO source code for a mere $50. It comes with manual and executables. The executables alone are $20. See http://www.qsl.net/zl1bpu/MICRO/SIMPLE/SimpleGPS.htm While this design does not use a Kalmann filter, it has pretty good holdover, and you can see how the phase detector, error integrator, filters, PID controller and D-A converter etc are done. The hardware is pretty simple. There is a PC monitoring and control program. 73, Murray ZL1BPU - Original Message - > As a lurker, I just want to chime in and say that I for one would love to see an open-source GPSDO implementation. [snip] ___ 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] FE-5680A firmware dump
Disassemblers are hardly rocket science. They are only a parser with a pile of memory to remember labels. Why not write your own? I've written them in the past (a long way in the past, and I've written cross-assemblers too), so I don't see anything difficult about writing one for the 8051. The nice part about writing your own is that you get to make it do exactly what you want. 73, Murray ZL1BPU ___ 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] Z3805 etc
Ulrich is right about the use of MTI 260 use in GPSDOs. I have a Korean-made Z3815A clone (it's labelled Agilent) which has a little daughter board with a 5MHz MTI 260 DOCXO in place of the original E1938A used in these models. I understand that there were production and reliability issues with the E1938A. 73, Murray ZL1BPU ___ 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] 57600 baud rate with Basic etc
Corby, Power Basic certainly does the job. However, there's a fairly big learning curve. I use Just Basic, which is a FREE cut-down version of Liberty Basic. While there are a few limitations, and some things you need to do aren't entirely intuitive, it works very well and the serial comms support is excellent. Not only will it do the higher speeds, it will also talk to any COM port you like, including those USB serial adaptors which typically live up at COM6 or higher. What's more Just Basic works great with Win7. I've attached a screen-shot of one of my programs which drives a serial DDS synthesizer (the FEI FE-56xx Rb synth). Looks good and works great. Regards, Murray ZL1BPU <>___ 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] "Best" GPSDO
Ulrich, I think this is a bit like discussing one's favourite wine or favourite stereo! Especially since many of the participants here will not have the capability to compare GPSDO performance reliably. I have a few GPSDOs, and it's my impression that of them all the Agilent Z3815A with MTI260 DOCXO has the best phase noise. Of course these units were originally equipped with an E1938A, and the later MTI260 version is not as common. I also have an E1938A, which I operate standalone. It is very impressive, excellent AD, in fact my best source now that I've given away my HP 5065A. There is some phase noise well away from the carrier, but I've put that down to my own construction (switching power supply noise). Another of my favourites with low phase noise is the Trimble/Nortel NTGS50AA, which has a CMAC/Rakon CFPO-DO OCXO. I've had no opportunity to measure the AD apart from what Lady Heather reports. This unit is physically large but is not power hungry and talks to LH very well. I also own a Z3801A, a Samsung GCRU-D and a small homebrew GPSDO with a CFPO-DO. Sorry, no Timepod for comparisons. 73, Murray ZL1BPU ___ 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] NTGS50AA RS422
Bjorn, Sorry, I have no further info re the RS422. Perhaps you could try tracing it from the processor or at least the 422 interface chip, if you can find it. Nobody so far has come up with a definitove pinout for the rear connector. About the only thing GPS Monitor does that's different is that it has a pop-up screen which repeats the status of the front panel LEDs. As for Lady Heather, you'll need to get the latest executable from Mark. It does work, no trouble at all. 73, Murray ZL1BPU ___ 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] NTGS50AA RS422
Bjorn, I don't know of an RS422 connection at the back of the NTGS50AA. There is a 'CMOS' level serial output (essentailly a monitor point) on the top pin, 7th row along from the end the power is applied. There are also 10MHz PECL outputs at the other end of the connector. I use either Trimble's GPS Monitor software or the latest Lady Heather, and I connect to the front panel RS232 connector. 73, Murray ZL1BPU ___ 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] NTGS50AA undoc 8F-AE data
Mark, Does that mean that there might be yet another version of LH forthcoming? The latest one works well with my NTGS50AA, and doesn't seem to miss much, although it has crashed occasionally when I change the screen resolution. Probably due to insufficient PC performance. I now have it running on an old P1 Tosh laptop. 73, Murray Greenman ZL1BPU ___ 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] NTGS50AA 1pps
Kevin, No, I've not found a 1PPS output. Not that I've looked, and I don't have the official pinouts for the big connector on the back. It would be easy enough to synthesize one, for example using a divider on one of the other products, resetting it if necessary with the 1PPS2 (2 sec) pulse. One of the things I did consider was driving the motor of a Quartz clock directly from the 1PPS2 signal. 73, Murray ZL1BPU ___ 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 94, Issue 21
John, Good stuff. Excellent news. You will be very impressed with the performance of the NTGS50AA. If you have any questions, or need real Trimble software to test it with, let me know. I did some spying on the comms using the Trimble software, but it was very difficult. TSIP is not a protocol that is easy to reverse engineer! 73, Murray ZL1BPU - Original Message - I've got one on order. Assuming it works, I'll get with Mark when it arrives and we'll put a new LH build together, based on whatever protocol documentation we can come up with. -- john Miles Design LLC ___ 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] NTGS50AA, better than Thunderbolt
Mark, I agree with you. I've been using an NTGS50AA here for some time, and it is an excellent unit with none of the thermal problems of the Tbolt. Easily as good as the old Z3801A, and much lower power consumption. I use the NTGS50AA with the Thunderbolt software in TSIP mode, although not all the messages work. While I've not tried the recently suggested method for making it talk to LH, I did find another crude way that works. If you get it talking to TBOLTMON or some similar software via the front panel, you can use LH on another computer on the rear-panel monitor port to monitor what comes back, but again, not all messages are supported. I'd love to see LH (and Z3XXX if possible!) support the NNTSG50AA fully. If anyone out there has documentation for the comms syntax of the NTGS50AA, we'd be pleased to hear! The 48V power supply requirements are a nuisance, which I got around using plus and minus 24V supplies. I use a UPS rather than a battery for backup. 73, Murray ZL1BPU ___ 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] HBG clocks
Marco, I have had an HBG-controlled clock for some years. Not that it ever received HBG at this range! The clock is an 'Irox HB13P' projection clock, and has the logo 'Official Swiss Time' on the front, which you can clearly see at http://www.irox.com/Web/en/Products/Archive/HB13P.htm. The user manual describes that it is controlled by HBG, which it checks once per hour. On the company's web site, http://www.irox.com/Web/en/Products/Clocks.htm, my clock is no longer listed as current, and I note that all the current models with LF receivers are quoted as DCF77 models. The HB13P is no great timekeeper on its own without HBG. I have to manually change it for daylight saving every 6 months, and each time I do I have to also advance it several minutes. So clearly it has an offset of around 10ppm, never mind how much it varies with temperature. 73, Murray ZL1BPU ___ 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] Simple GPSDO
Two thoughts re Simple GPSDOs: 1. For a conventional 1pps approach, see 'A Simple GPS Disciplined Reference" http://www.qsl.net/zl1bpu/MICRO/SIMPLE/SimpleGPS.htm, by yours truly. It uses a high performance 10MHz OCXO and gently disciplines it. Despite not having a Kalmann filter, the holdover is excellent and the Adev is almost as good as the OCXO allows. 2. The excellent 10kHz design by James G3RUH http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm requires a 10kHz GPS source, and folk on this group asked where you can get a modern GPS module with 10kHz output. One suitable answer is any of the u-BLOX modules, such as the LEA5-P. These have completely programmable pulse outputs in 1us steps (width and duration). I use an older u-BLOX Antaris 4 development kit which is Atmel based, and it also has a programmable pulse output. 73, Murray ZL1BPU ___ 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] 63.8976 OCXO is useful
Hi, I can think of at least one excellent use for the unwanted 63.8976MHz OCXO that comes free with some of the recently offered FE-5680A units. It would make a great reference for a DDS synthesizer, such as an AD9852/AD9854. These chips have a 4x reference multiplier capability, and thus would provide a clock at ~256MHz. How useful it would be to have a DDS synthesized signal generator with sub-milliHz steps, low phase noise, controllable phase and output level, and 0 - 100MHz output capability! 73, Murray ZL1BPU ___ 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] FE-5680A results
Bert, There's a very nice way to separate diurnal thermal sensitivity from long term ageing. It applies equally well to Rb sources as to OCXOs, which is where I've used it. What you do is set up to make frequency observations against a more stable reference (of course in this case a GPSDO or a similar), and then make several observations per day for a week or so, preferably at or about the same time of day each day. Then you plot the results using a spreadsheet, as ppb offset on the vertical axis and time of day (NOT total elapsed time) on the horizontal axis. What will result after several days of observations is either a zig-zag or a spiral, depending on the relative sizes of the thermal and ageing effects. You can extract the ageing rate out quite nicely by adding a column with an estimated ageing rate which you add to the measured offset. If you then plot this against time of day you should end up with a static rough retraced circle or line when the estimated offset is correct. The width and height of the result gives you an estimate of the thermal sensitivity with time of day. If you are able also to plot against ambient temperature instead of time of day, the same process applies, and you can extract the thermal sensitivity. 73, Murray ZL1BPU ___ 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] Ways to use unclean RF from FE-56xx
As noted by others, the internal Rb locked signals of some FEI units are not especially nice sine waves. One way to profitably use them is to operate an external DDS generator. The phase noise of the source will afffect the result, but not the harmonics. I have an FE-5680B which has an internal 60MHz source, which I use with an AD9854 DDS kit (an old one with a printer port control interface). It will also work with 10MHz, since the DDS has an internal clock multiplier. The resuilt is a DDS operating 0 - 50MHz or more with uHz resolution. 73, Murray ZL1BPU ___ 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] AD9832 in FE-5680A
Bert, Your comment about the AD9832 being a 25MHz part made me think, and I too wonder how it might all work. The data sheet calls it a 25MHz part, and I agree with you that it might be expected that some extra division occurred between the ~60MHz Rb loop and the synthesizer MCLK. That's not the case however. I don't know how it's achieved, but the FE-5650A and FE-5680A (the versions with AD9832 and user-programmability, I mean) do in fact appear to operate with a ~60MHz MCLK. I support that statement with two facts: 1. The AD9832 in these models is capable of generating moderately good 12MHz output, which it certainly would not with a 25MHz MCLK. 2. The frequency calculations used give you a step size of about 10mHz, and as you will realize, 50MHz/2^32 is about 10mHz. I've used the ~50MHz figure (actually either 50.255MHz or 60MHz) in my software. Does anyone know how we can resolve this apparent inconsistency? 73, Murray ZL1BPU ___ 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] FE-5680A power
It's my experience (and I have two FE-5680A and an FE-5680B, plus a couple of FE-5650As) that you don't need a +5V supply with the FE-5680x devices, just a +15V supply. Now of course the model number has little to do with what we find inside - there seem to be many variants - so I recommend that before you power it up, you look inside and identify what regulators there are internally. They will be on the end PCB which holds the DB9 connector, and bolted to the heatsink block down the centre of the unit. If you've two regulators, one will be for +12V, the other +5V, and so just feed +15V. You should be able to trace the regulator inputs back to the connector to confirm. If there is no +5V regulator (and I'd be surprised), then clearly you'll need to work out where to provide the +5V, and again I recommend tracing back from the power pins of some ICs to the connector to be sure. Much better to be safe than sorry! 73, Murray ZL1BPU ___ 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] Better option than oil
Folk looking for alternatives to dunking things in oil might consider trying a variant of the following technique which I have used with success: The thermal stability of TCXOs and XOs can be improved considerably for experimental purposes by slowing down the thermal time constant between the device and ambient. A simple technique which I have used consists of a recycled polystyrene box (picnic box, frozen food or dry ice transporter) filled with dry sand. I place the device under test in a plastic bag or other small container sealed as far as possible to keep sand out, and bury it in the middle of the sand. The sand has a high thermal mass, and that combined with the polystyrene insulation gives the device a thermal time constant to ambient of many HOURS. While I'd not suggest this is the right solution for an OCXO intended for use in free air, it is a way of achieving impressive short and medium term stability with simple unheated devices, especially if operated in a modestly controlled (e.g. air-conditioned) ambient environment, since the time constant is significantly longer than the ambient temperature cycling. The technique is almost good enough to remove diurnal ambient temperature variation. 73, Murray ZL1BPU ___ 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] Insulating OCXOs
Bob, Many OCXOs, and definitely the CMAC (now RAKON) STP2145A, use ambient compensation technology. It is not possible to place the heater, the crystal and the temperature sensor in exactly the same place, and consequently there will be a thermal profile within the OCXO which depends on the oven design and the external environment. The ambient compensation corrects for this effect. (The temperature is measured inside the unit in two places in order to determine the thermal profile, and a calibrated amount of this differential measurement is used to correct the oven control). If, by lagging the OCXO, you change the thermal profile, which you will, the internal compensation set during calibration will be compromised. This will make the OCXO more sensitive to changes in ambient temperature than it should be. Whilethis may not apply to double-oven oscillators, I still don't beleve it is a good idea to lag them. You achieve nothing useful by reducing the power consumption of the OCXO through lagging: place the OCXO where it can have modest convection, but no draughts or insulation, and preferably no undue heating from the nearby equipment. 73, Murray ZL1BPU ___ 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] OCXO burn-in
Paul, Whenever you make changes to the physical setup you will cause mechanical disturbance to the OCXO which it is likely to take some time to recover from. A couple of days continuous operating should suffice. Add to that an hour for every day it's been switched off. Even tipping the unit upside down changes the G force on the crystal and affects the frequency. Bumping it could change it for a couple of days. As for the environment of the OCXO, try to place it where you don't affect the natural external temperature of the OCXO. Preferanbly don't elevate the case temperature too much, but definitely don't lag the OCXO, put it in a Dewar or subject it to draughts (e.g. air from fan). Respect the need for the OCXO to maintain the internal temperature profile it was calibrated at. The RAKON/C-MAC OCXOs, especially the CFPO-DO and the single-oven types in the typical GPSDO have pretty good ambient compensation, but attempts to lag or cool the OCXO won't be helpful as the thermal profile within the oven could change. Anybody contemplating making their own high performance oven oscillator might as well forget it. The design of the crystal, thermal environment and oven control are all very tightly coupled. These days really good OCXOs, better than anything you could make, can be had at sensible prices. 73, Murray ZL1BPU ___ 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] OCXO settling
There are of course many levels of performance in OCXOs, but in general the ageing slows down with time, and veteran OCXOs can be very good. I recently tested the OCXO in an old HP5245L counter (circa 1970), last calibrated in 1985, and it was still within 100ppb of 10MHz after 24 hours warmup! One point other correspondents didn't answer is the isue of retrace. When an OCXO is unpowered for some time, it undergoes a further ageing process when it starts up next. This is specified in some data sheets, and can typically require an hour of burn-in for each day left unpowered before specifications are met. To answer the question about whether it is best to leave an OCXO turned off when not in use (so it doesn't 'wear out'), I'd suggest that if you don't plan to use it again for a month, turn it off - otherwise leave it running all the time. It should get better with time. 73, Murray ZL1BPU ___ 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] Plessey PR152
My thanks to those who suggested I join the vintage radio forum www.vintage-radio.net. I have joined, and it certainly looks like a very helpful group. 73, Murray ZL1BPU ___ 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 - Plessey PR152
I realize this is very off topic, but I am ever amazed by the wide reaching interests of this group. Does anyone have any information at all on the Plessey PR152 receiver? It is a 'short wave' receiver (rather than comms receiver) from about 1962, with Ge transistors and an amazing film-strip dial. Ideally I'd like a schematic or manual so I can fix the receiver, but I'd be grateful for any crumbs, such as suggestions about who might know more about the receiver. I can send photos if anyone is interested. Contact me direct if you are. Regards, Murray Greenman ZL1BPU ___ 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] Oscillator Buddy
Warren, I agree with other responders that a closed loop approach to OCXO minding is feasible using a simple micro and D-A. I designed a system which has as its main focus low ADev and reasonably good frequency accuracy, without necessarily requiring the tight timing of a commercial GPSDO or the use of high resolution D-A. You might consider my system 'loose' control, as it relies on the OCXO being pretty good in the first place. It just corrects for long term effects such as ageing. What I came up with may be helpful. Essentially it phase locks the OCXO to GPS 1pps, but does so with extremely long integration times (hours), and with modest gain, so provided the OCXO is not subject to sudden temperature extremes or has an excessive ageing rate, will provide good control. As others have suggested, if you limit the control range (in my case I have a manual coarse setting) you can achieve very good closed-loop control with limited D-A resolution. I used 15 bit PWM, using a 12-bit timer and 3 bits of dither, providing a range of under 1ppm and a step size of about 3e-11. The system has no predictive capability, but does achieve (with a good OCXO) quite good holdover performance. By studying the control voltage over the last year, I've determined by extrapolation that manual intervention (coarse adjustment) will be unlikely within 10 years. I used a small AVR processor, did all the counting and maths in the processor, and operated the analog circuitry from the internal reference in the OCXO, resulting in very good thermal performance. The design is described in some detail at http://www.qsl.net/zl1bpu/MICRO/SIMPLE/SimpleGPS.htm. Regards, Murray Greenman ___ 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] FTS 1050A
The FTS 1050A sounds like a very nice toy. I agree with one of the other suggestions - use the device as a reference for a DDS generator, so you can have any frequency you like, with high stability. Many of the newer DDS chips have excellent performance, and in addition include a clock multiplier. I have an AD9852 kit, and it can multiply by up to 20, so would give ~120MHz as the reference from your FTS1050A, and then have useful output to 30MHz. The synthesizer is 48 bit, so the steps are very small. I use mine with an odd-frequency FEI Rubidium source (about 60MHz) and the results are very good - any frequency I want with microHz resolution. Regards, Murray Greenman ___ 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] Broadband synthesizer (WB6BNQ)
Bill, One method I've found convenient is to use a DDS Development kit such as the AD9852 one and drive that from a Rubidium or GPSDO source. I have a 60MHz FEI-5680B driving mine and easily get 0 - 200MHz out. No, it won't give all the range you want, but there are few alternatives that will, certainly not at the price. You can run these kits directly off a 10MHz GPSDO, using a higher multiplier setting, but they do work better if the reference is higher. They provide micro Hz stepping with no trouble at all. The only inconvenient thing with my older kit is that the computer interface is via a parallel (printer) port. I've used mine to zero-beat against the GPSDO at 10MHz and (using a Vector Voltmeter) compare the phase shift over 24 hours. It has shown me that not all GPSDOs are created equal! 73, Murray ZL1BPU ___ 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] Lady Heather
We had the REAL Lady Heather on TV last night here in New Zealand! It was the CSI episode about cats. Any tenuous connection with Time-Nuts, perhaps? Murray ___ 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] Synchronous LF Reception
Hi, There was a discussion a week or so back about SoftPAL and techniques for LF reception which would allow us to study the phase and signal strength of VLF and LF transmissions. Effects to be studied include detection of solar events and prediction of earthquakes. At the time I forgot to mention Clicklock by Con ZL2AFP (http://www.qsl.net/zl1bpu/SOFT/click.htm). There's also a simpler program by Scott VE7TIL, and another by Peter G3PLX who invented the idea, although I don't have a URL for either of those. While nowhere near as sophisticated as SoftPAL, Con's Clicklock is FREE, and will do the job required. It displays a pair of graphs showing relative signal power and phase angle, as well as an integrator phasor diagram. It will handle carrier phase integration times from 1s to 1000s or more and with careful setup can be used up to 500kHz. The Clicklock technique was developed by Peter G3PLX, and uses a GPS 1pps reference fed into the computer sound card. It uses this reference to sample the phase of harmonics of the same 1pps pulse fed into the receiver antenna. If the receiver is tuned perfectly to an integer 1Hz step, the phase of the harmonics within the receiver bandwidth will be much the same (not zero, as it depends on receiver delay, and group delay in the receiver has some effect). If the receiver is mistuned, each successive harmonic will have increasing or decreasing phase. The software operates an NCO to reduce the incoming signal to zero Hz, and this NCO is steered by analysis of these harmonics to remove errors due to drift and offset in the receiver. The zero frequency I and Q components are then integrated over time to recover the signal. With a conventional ham receiver and LF antenna you can easily achieve lock and use 100 sec or more integration times. This technique does of course make the study of drying paint seem very speedy, but it is effective and VERY sensitive. On the web page referred to above is an example of WWVB (60kHz) recorded with 600 second integration time, and you can clearly see the hourly phase advance. This was recorded at a range of 10,000km. I have also copied signals from Europe in this way, and Con has copied (at 500km range) my extremely weak 10uW EIRP test transmissions on 181kHz which include intentional phase changes for identification purposes. 73, Murray ZL1BPU ___ 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] Softpal VLF software
I've recently been in touch with Kit, the developer of Softpal (lives in Dunedin, New Zealand). He took some effort to locate. The software is commercial, and runs on a Labchart (commercial instrumentation) package which you also have to buy, and that's the expensive bit. The software does indeed do as he claims, and we have had some useful discussions. Like you guys, I'd love to try it out! I'm trying to negotiate a shared development for use with a conventional Windows platform. Kit is interested in doing this, but don't hold your breath! Regards, Murray Greenman ZL1BPU ___ 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] HP 8508A Vector Voltmeter
Hi, I found an old HP 8508A in the store room at work, and it looks like a useful candidate for Time Nuts activities. It seems to work OK, and while it has GPIB, I don't at present have GPIB on my computer, but I can connect up a chart recorder. Has anybody any comments about using this instrument for comparison of references, for example? 73, Murray ZL1BPU ___ 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] Symmetricom board - please help with information
I've been given a very interesting board made by Symmetricom. For photos and details, see: http://www.qsl.net/z/zl1bpu/PROJ/Symm.htm The board clearly has all the ingredients of a GPSDO - nice OCXO, GPS receiver, 10MHz and 1pps outputs, TCXOs and other outputs. The OCXO has SPI controlled VCO input. However, the power connections and communications aspects are far from normal, and I would like to hear from anyone who can tell me more - I'd like to make use of the unit if I can. I would particularly like to know: * What it does * What the connector pinouts are * How I can power it up * How I can talk to it All the details I have and some really clear photos are on the web page referred to above. I found that for some reason the links to the high res photos don't work this morning. If they don't work for you, - try: http://www.qsl.net/z/zl1bpu//PROJ/SYMM061.JPG http://www.qsl.net/z/zl1bpu//PROJ/SYMM060.JPG 73, Murray ZL1BPU ___ 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] Choice of Rb vendor
Joe, If all you need is a fixed 10MHz source, you might be better getting an Efratom LPRO-101, which are available from the same sources. The LPRO-101 doesn't need a heatsink, and does not have the confusing array of different versions and options that the FEI units suffer from. As for suppliers, I have had good results with 'Fluke.1' also known as 'NBBob', and probably other aliases. He is fast and reliable on delivery, and replaces faulty equipment without argument. I have no experience with any other suppliers. Most of these suppliers seem to have little knowledge of what they are selling, so don't trust the technical details given without checking them yourself. 73, Murray ZL1BPU ___ 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] FE-5680A pinout
The confusion is understandable. There are so many different variants of the FE-5680A, and they are not easy to identify. Some of the information you see out there is from folk who measure the voltage on the pins with a meter, not understanding what they are looking at. When I've investigated such devices (I have several FEI units) I start by tracing my way back from the power supply regulators to determine where the power goes in, and what it should be, to avoid mistakes. It's also been a useful technique with things like GPSDOs where nothing is known about the pinouts (Trimble NTGS-50AA for example). Sure is frustrating when you have one that isn't frequency agile! One of my FEI units is an FE-5680B with only 1pps output. The Chinese supplier thought it was faulty, but the 1pps pulse is only 5us wide, and isn't present until the unit has locked. I found a very useful 60MHz reference inside the unit as well. 73, Murray ZL1BPU ___ 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] FEI FE-5650A and FE-5680A caution
Jerry has described the situation fairly well. You take pot luck, and the Chinese supplier does not know which are which. Out of four units I have, two are remote controllable, one is fixed at (reasonably close to) 10MHz, while the fourth had no output at all. I've since discovered that this last unit has a 1pps output, and I was also able to recover a useful 60MHz output from it by digging inside. If you end up with a fixed ~10MHz unit, it's still useful as a portable reference. It doesn't matter what the exact frequency is, so long as it's stable and repeatable (within your measurement requirements) and has a nice low ageing rate. Murray ZL1BPU ___ 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] Portable standard - Rb query
Joe, I have several of the FEI units. You pay more for these, because (assuming you get the right one) they have a DDS synthesizer included, which (with suitable modification) allows them to operate from about 1kHz to 15MHz in 10mHz steps. Some models require +15V and +5V, others just +15V. My preferred unit is the FE-5680A. I have mine mounted on a large aluminium plate and powered by a switch-mode computer supply. I have set the default frequency to 10MHz. The LPRO type are fine if you want a simple fixed 10MHz reference, and are in general cheaper and use less power. As for lifetime, they seem to go forever. That said, there's no need to power them continuously since (in my experience) they are close to their final frequency 5 minutes from a cold start. Power consumption is higher than an OCXO, but they really do make a great portable standard. That's what I'd use (in fact, that's what I do use). Murray ___ 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] Oncore battery backup
Why not just put a bigger battery in your UPS? I have a couple of old ones, and they run just fine with an old car battery, and thus give me many hours of backup for my Trimble/Nortel GPSDO. Just be careful though - in some UPS units the battery is live to the mains! The APC ones seem to be OK. Murray ___ 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] JJY40
I've also observed that JJY40 is now off the air. It has been excellent
reception down here in New Zealand for many years, generally better than
the JJY signal on 60kHz, where of course it competes with other signals.
JJY40 was typically strong enough to hear by ear during the day as well
as at night here, and fades considerably for an hour or two at sunrise
and sunset. There is some evidence that Japanese radio-controlled
('Atomic') clocks work in New Zealand using this signal, as there is no
closer source.
73,
Murray ZL1BPU
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[time-nuts] FE5860A CONNECTIONS
Dan, Yes, you are right. There are so many variants of the FE-56xx devices that I'm sure even FEI don't have a clue which is which! The FE-5680 family are invariably single supply, although the connectors vary. Pull the lid off and with an Ohm-meter trace the input to the regulators back to the DB9 or DB15 connector to be sure. +15V should do the job. As far as my experience goes, only the 5650 family require dual supply. Anyway, a sure way to check is by seeing if there are both +12V and +5V regulator chips fitted in the power supply section behind the panel. If you have any more questions, please ask. I have four different (and working) FEI units of various models. 73, Murray ZL1BPU ___ 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] STP2145A
Robert, I've attached the data sheet for the STP2145A. The device is 12V operated, and has an internal 8V reference which you can use to supply the EFC circuit. Have a look at http://www.qsl.net/zl1bpu/MICRO/SIMPLE/SimpleGPS.htm, where I describe a simple home-brew GPS Disciplined Reference based on an oscillator similar to the STP2145A. The stability is impressive for such a simple unit. RAKON France (used to be C-MAC) make a wide range of high performance OCXOs. 73, Murray ZL1BPU C-MAC STP2145A.pdf Description: C-MAC STP2145A.pdf ___ 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] Pulling oscillators
Don, You haven't explained how much you want to pull the oscillator, but assuming it's less than 1ppm, what you suggest is quite viable. Replace one of the caps in the Pierce oscillator PI network (preferably the output one) with an NPO one of slightly smaller value and add across it a varactor. If your intention is to externally lock to (say) GPS, the smaller the range you can get away with, the better. How much range you allow depends on the intended application, including how much thermal compensation is required (defined by crystal cut angle and therefore pullability) and how much ageing compensation is to be expected. You can do some pretty subtle things for very small adjustment range. In one design I employed the small change in oscillator chip input capacitance with supply voltage - I removed the zener on it's power supply and drove it from a D-A converter. In another I heated the crystal with PWM from a phase detector as a means of holding the frequency (operated the AT cut crystal on the slope of its Bechmann curve at around 40°C). In an old SSB transceiver I locked the 7.MHz reference (similar oscillator to the one you describe) to GPS by phase comparison every third second (as though the reference was 1/3 Hz). The micro doing the locking simply ignore two out of three phase measurements. In short, yes, it can be done. 73, Murray ZL1BPU ___ 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] NMEA time off
Many older GPS units sending NMEA at 4800 baud will in effect indicate one second slow, either all the time or some of the time, if there are too many GPS sentences turned on. There's too much data in the queue. Either drop the number of sentences enabled, or increase the baud rate, or both. Another source of delay is the computer. It may take up to a second for the serial data to get to the screen from the com port. Try a different computer and/or terminal program. The best source of time is of course the 1pps pulse, but you still need to know which UTC second each one refers to! 73, Murray ZL1BPU ___ 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] Earthquake meets time ball
Hi, You may recall we discussed here some time back about how time was disseminated in days gone past, and mentioned Time Balls at various locations from Greenwich onward. I'd forgotten that there was (and still is) one at Lyttleton, NZ, right at the epicentre of the big earthquake. This historical building has as a result been badly damaged, but the ball and its tower still in place. See http://www.nzherald.co.nz/nz/news/image.cfm?c_id=1&gal_gid=116950&galler y_id=116940#7382812 73, Murray ZL1BPU ___ 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] Freq cal to 1ppm without GPSDO
John, I've had quite a bit of experience doing what you want to do, and have tried several methods. TV used to be a good way, but now that everything's gone digital that method is out. Despite advice to the contrary, comparing with WWV or similar on HF is NOT reliable to 1ppm. This is because there is Doppler on the short wave F-layer signal to the tune of several ppm. (It can be done if you are within ground wave or E layer range). An experienced user can achieve results with WWV by understanding when the propagation is E layer, and always using the same time of day. 1. My best advice is to get hold of a cheap GPS module with a 1pps (seconds pulse) output. Connect it up, and when you have a fix, use the 1pps to trigger your digital oscilloscope. Set the timebase to 1us/div to start with, and ultimately 100ns, and observe the 10MHz output of your TCXO. You will see the waveform drifting slowly. Counting how long it takes to slip one cycle will tell you how far off the TCXO is. If you have a counter with Time Interval mode capability, you could use that, using the GPS to start and 10MHz to stop, again observing the drift. 2. The reference oscillator in a GPS receiver isn't any help to you. While they need to be stable, they are NOT usually controlled by the GPS receiver. If you know what you are doing with the GPS NMEA 'clock bias' telemetry, you can work out what the receiver reference is doing, and compare with that, but that's only for experts. 3. If you want to divide the 10MHz down to 2Hz, you can run a 'Quartz' clock mechanism with second hand, and then, although this method is very slow, compare clock time with WWV's minute marks. A slip of 1 sec every two weeks is about 1ppm! Bear in mind that few TCXOs have a spec better than ±2ppm, and will often have other dynamic and hysteresis effects amounting to the same order. If you can find an OCXO to use as reference, so much the better. Method 1 is really simple to do and positively foolproof! 73, Murray ZL1BPU ___ 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] FE-5680A
Bud, I have a couple of these units going nicely, but I agree with Bob, you are best to sort the pinouts for yourself since they vary. Take the lid off (it's fairly simple, screws on the base, on the side and by the connector) and identify the 5V regulator input, then use an Ohmmeter to find where the power comes in. It's likely that the unit is +15V (single supply) powered, and I agree, there should not be a 5V input required on the 5680A. If the power connector is DB9, then almost certainly +15V will be pin 1 and ground (15V return) pin 2. You need nothing else to try it out. Once you have power applied and it's running, you should be able to identify the other pins. The one of most interest is the lock indicator, which is open collector and will operate a LED. If you have the version with the DDS synthesizer, see http://www.qsl.net/zl1bpu/PROJ/Ruby.htm for info on adapting it to give improved frequency response and computer control. 73, Murray ZL1BPU ___ 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] SECAM vs NTSC
Rick, Maybe the French had a point... we all know NTSC stands for 'Never Twice Same Colour'! Regards, Murray Greenman ___ 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] UBLOX 1pps vs Z3801A
John, The Z3801A 1pps is based on the mean UTC/GPS time, but regenerated from the local (very stable) 10MHz reference, so has little jitter. The UBLOX GPS module 1pps output is more or less instantaneous, so has jitter resulting from each individual position solution. If you provide it with a known position, the jitter will be reduced, but still not as good as the regenerated 1pps from the Z3801A. The jitter is much greater if 'Selective Availability' is on. One of the important factors in designing and building your own GPSDO is to shield your stable OCXO from this timing jitter. The aim is to have the going rate of the OCXO follow UTC/GPS, not the jitter, SA, fix solution or diurnal satellite variations. Murray ZL1BPU -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of time-nuts-requ...@febo.com Sent: Wednesday, 22 December 2010 11:47 a.m. To: time-nuts@febo.com Subject: time-nuts Digest, Vol 77, Issue 97 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than "Re: Contents of time-nuts digest..." Today's Topics: 1. West coast LORAN (Hal Murray) 2. Re: UBLOX GPS board testing (John Green) 3. Re: LORAN C antenna thoughts from the group (paul swed) 4. Re: LORAN C antenna thoughts from the group (Poul-Henning Kamp) 5. Re: West coast LORAN (paul swed) 6. Re: UBLOX GPS board testing (paul swed) 7. Re: LORAN C antenna thoughts from the group (paul swed) 8. Re: What is the best way to multiply a 10 Mhz (Gerhard Hoffmann) -- Message: 1 Date: Tue, 21 Dec 2010 13:00:55 -0800 From: Hal Murray Subject: [time-nuts] West coast LORAN To: time-nuts@febo.com Message-ID: <20101221210055.66c18800...@ip-64-139-1-69.sjc.megapath.net> Content-Type: text/plain; charset=us-ascii Has anybody on the west coast tried to pick up LORAN stations from north west Pacific? Does anybody have any idea of how long those transmitters are likely to keep running? -- These are my opinions, not necessarily my employer's. I hate spam. -- Message: 2 Date: Tue, 21 Dec 2010 15:26:54 -0600 From: John Green Subject: Re: [time-nuts] UBLOX GPS board testing To: time-nuts@febo.com Message-ID: Content-Type: text/plain; charset=ISO-8859-1 I tried substituting the 1 PPS output from the Z3801 and comparing it to its own 10 MHz output and find the same jumpy behavior as I get with the UBLOX boards. Well, not exactly the same but pretty much. Now I am confused. I expected the 1 PPS to be in lock step with the 10 MHz. -- Message: 3 Date: Tue, 21 Dec 2010 17:09:10 -0500 From: paul swed Subject: Re: [time-nuts] LORAN C antenna thoughts from the group To: j...@quik.com, Discussion of precise time and frequency measurement Message-ID: Content-Type: text/plain; charset=ISO-8859-1 John I believe that it is usable certainly from the pre-amplified whip that I picked up 90070 last night on. The downside is you have to be awake at 0300. One of those nights. As I mentioned my GPS comparison was not very good because I forgot to rehook the gps antenna up to the hp3801. Do. Explains that pretty well. Is there a real advantage to a 4 or 6 foot big loop compared to a small loop? I use a 3 foot loop on wwvb/preamp and that works well. One other point on the wavefrom on loran c. It was constructed to minimize the impact of skywave influence on the receiver. Essentially making it easier for the receiver to distinguish between the two. Thast what I hadread in the loran docs. Regards Paul. PS I thought the bw was +/- 10KC and even wider. On Tue, Dec 21, 2010 at 3:11 PM, J. Forster wrote: > I was more interested in reducing the BW, rather than increasing it. > > Years ago, I bought up some of the resuidual of Appelco, a New Hampshire > LORAN company that made units for Raytheon. Included were a bunch of > active tunable filters, designed to "tune out" interference. However, > there is no documentation. > > I was just toying with the idea that a good shielded (possibly active) > loop, the tunable filters, and an Austron 2100F might still be usable on > the east coast. > > FWIW, > > -John > > > > > In message <53187.12.6.201.2.1292957970.squir...@popaccts.quikus.com>, > "J. > > Fors > > ter" writes: > > > >>I remember reading somewhere that the envelope of the LORAN pulses was > >>shaped to reduce the transmitted BW. > > > > The envelope is designed for two things: sensible BW and ease of > > producti
[time-nuts] Plastic covered OCXOs
I could tell you but... There's a lot of interesting IP in these little guys! Regards, Murray Greenman RAKON ___ 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] Setting clocks 100 years ago
Navigators used chronometers to determine their longitude. If they were stopped in one place long enough, they could work out longitude by a complicated process of star and lunar observations; however, when they left an established port, they usually took with them a time standard based on local measurements of the sun and the known location of the port. These measurements used a device called a 'Transit', which was a simple telescope mounted so that it pivoted in elevation, but was fixed N-S in azimuth. Midday was marked by the time at which the sun transited the telescope. It thus had higher resolution than a sundial. Getting N-S axis correct involved determining by iteration and surveying the axis that gave maximum elevation at time of transit. Once the transit was observed, a large ball on top of the building was dropped, indicating midday, and in some locations a cannon was also fired. Ships in port could observe the ball drop and hear the cannon. To this day the ball drops at midday at Greenwich. 73, Murray ZL1BPU ___ 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] Distribution Amp suggestions
Hi, We have more expensive distribution amps around the production facility here at RAKON than I'd care to count, and always seem to need more. I am looking for additional units as the requirements expand, something like the Symmetricom 4036B which we already use. Our need is for 10MHz distribution. Since we need to purchase several of these, can anyone suggest a unit with similar performance and quality that would be lower cost than the Symmetricom 4036B? Regards, Murray Greenman RAKON Ltd ___ 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] Drake DSR-2 Rx
Nigel, Thanks very much! I'm not able to download it from here at work (the IT Police policies block so much the internet isn't fun any more!), but will as soon as I'm home. I have the receiver going quite well, and it certainly looks impressive with its Nixie display. It's no great performer by modern standards of course (and not like the marvellous Redifon/Harris/RACAL receivers). 73, Murray ZL1BPU Date: Fri, 17 Sep 2010 03:53:40 EDT From: gandal...@aol.com Subject: Re: [time-nuts] Drake DSR-2 Receiver manual To: time-nuts@febo.com Message-ID: <48c02.7b05af0d.39c47...@aol.com> Content-Type: text/plain; charset="US-ASCII" In a message dated 16/09/2010 23:58:47 GMT Daylight Time, murray.green...@rakon.com writes: know this is a bit off-topic, but I wonder if any of you guys have available the manual for the old (1970s) Drake DSR-2 receiver? - Hi Murray I suspect PremRX would be the best place to ask, but you're in luck so perhaps you made the right choice after all:-) It's too big to email so have uploaded it to Rapidshare.. _http://rapidshare.com/files/419537735/Drake_DSR2.pdf.html_ (http://rapidshare.com/files/419537735/Drake_DSR2.pdf.html) regards Nigel * ___ 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] Drake DSR-2 Receiver manual
I know this is a bit off-topic, but I wonder if any of you guys have available the manual for the old (1970s) Drake DSR-2 receiver? I've you are able to send me a PDF copy, I'd be most grateful. 73, Murray ZL1BPU ___ 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] Homebrew WWVB simulator
I designed and built a similar thing a while back, which emulated the full VNG time code (which could be decoded by 'Radio Clock' and other clock software). My unit was GPS locked, using two microcontrollers, but it wouldn't need to be that complex for setting clocks/watches. It generated all the required ticks and time code pulses as various audio tones using a direct digital synthesizer which operated in an interrupt in the micro firmware. The WWVB code would be fairly straight-forward to implement, even including the phase advance, if you generate the 60kHz directly using DDS within the micro. I might look into that as a future project. My 'VNG in a Box' design is at www.qsl.net/zl1bpu/MICRO/VNGBOX/ Regards, Murray ZL1BPU ___ 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] Basic question regarding comparing two frequencies
You guys are trying to crack a nut with a sledgehammer! For a start, as Didier says, you can't possibly read the frequency of a sky-wave signal to 0.01Hz in any short time frame since the Doppler on the signal can be as much as 1ppm (i.e. 10Hz at 10MHz). You can only infer it closer than that by studying the frequency in the very long term. In addition, you'll never know how much of the daily variation is ionospheric, and how much is due to thermal changes at the source. For what it's worth, the method I use for HF frequency measurements is much simpler. I use a receiver which I can lock to my GPSDO (RACAL RA6790/GM and HP Z3801A), and thereafter calibration is simply an issue of getting the sound card sampling rate correct at the software spectrum analyser, which you can do with a 1kHz reference from the GPSDO. No complicated signal generators, signal injection, or AM mode with AGC problems. I use Peter G3PLX's SBSpectrum as the analyser, where you can trim the sample rate in tiny steps. It also has a frequency resolution of 25mHz, which is more than adequate for HF. My combination has won FMCs, but I still can't resolve 0.01Hz off-air. Whatever you do (with a sky wave signal) must be done over a long time frame in order to be sure of getting closer than 1ppm. 73, Murray ZL1BPU ___ 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] Rapid startup GPSDO
Jim, Would an inexpensive Rubidium unit do what you want? I know it won't be closer than a few ppb, but in my experience (LPR101, FE-5650A, FE-5680A) they are stable inside about four minutes. The big advantage is they don't need GPS at all. Regards, Murray ZL1BPU Message: 1 Date: Wed, 14 Jul 2010 06:42:50 -0700 From: jimlux Subject: [time-nuts] rapid startup GPSDO To: Discussion of precise time and frequency measurement Message-ID: <4c3dbeda.7010...@earthlink.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Is there some (inexpensive) GPSDO that has a "time from power on in an unknown location to reasonably stable" in the <5 minute category? Frequency accuracy in the 1E-9 range would be fine. A regular old GPS has a Time to First Fix well under that, and it should be cranking out 1pps pulses with 1E-7 or 1E-8 precision pretty quickly.. Would it be fair to say that after 100 seconds, one could theoretically have driven that down another factor of 10? As I understand it, a thunderbolt needs some number of hours after turn on to stabilize, but just how bad is it after, say, 5 minutes. ___ 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] Yet another GPSDO - locking to 10MHz
I have a design which locks a high performance 10MHz OCXO to a 10MHz source which should work equally well with the LEA5, or any source of 5 or 10MHz. I designed it for use with a distributed factory GPS reference which has picked up noise, hum and phase modulation, in order to deliver a high quality but GPS locked reference direct to equipment. The design adds nearly three orders of improvement. Essentially it divides the incoming 10MHz by 16384 and compared the phase with a similar division from the OCXO, within an ATTiny2313 micro. The phase detector is a D-flip-flop type implemented in software (in interrupts), and it delivers a locked reference with ADev around 10e-12 for Tau between 1s and 20s. The micro also keeps a real time clock and does various background monitoring and telemetry tasks. There is PC monitoring software as well. There are only four chips in the design. While I can't share the code (belongs to my employer), the idea is simple enough and I could share the schematic. Eight of these units have been built. I used the excellent Rakon STP2402E OCXO. Regards, Murray Greenman ZL1BPU ___ 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] Z3815A
Magnus, The Agilent Z3815A is a very nice unit, and fairly easy to get going. The main problem is software, which we had to specially write, although some versions of Ulrich's Z38XX work with it quite well. (The problem is subtle differences in the SCPI syntax). Yes, the backplane carries all the required signals except the serial comms. Use 2.54mm spaced header pins to connect. For power, use a little Veroboard with headers on. The DC supply connects to pins A54 to A58 (B) and A59 to A63 (A). Polarity is unimportant, and it operates from regulated 20 to 56V. A 24V 2A switch-mode plug pack will do the job. This supply is isolated from the rest of the unit. There are other outputs on the backplane, which I will leave you to find! They include 19.6608MHz, 4.096MHz and 1.544Mhz. The coaxial block consists of three independently buffered 10MHz sine outputs at +13dBm (B1 to B3). The GPS antenna (5V active) connects to A4. I've never had any success finding matching connectors at a sensible price, and so simply solder the antenna cable and 10MHz outputs to the back of the board. This connector is not soldered in, but simply held by its insert barbs. You can't prize it out as a unit, but I'm told that if you break up the plastic you can remove the inserts one at a time, although I've not tried it. The serial comms is wired with the wrong connector sense, so it's best to make a dedicated cable, or use a Null Modem cable with a DB9 M-M adaptor at one end. It doesn't talk unless spoken to, and uses 9600-N-8-1, SCPI protocol. If you have one of the earlier Z3815A units, you will find the superb HP E1938A 10MHz reference oscillator inside. There were manufacturing problems with these units, I understand, and later ones (like mine) have a Milliren 260 series 5MHz DOCXO (with excellent specs) on a daughter board made by Symmetricom. There is a full (unofficial) manual and software available on CD for the Z3815A - write to ksca...@bytecan.com.au. The manual lists all known commands, and also covers the Korean clone of the Z3815A, which is electrically and firmware different but externally identical. Software includes a monitor program with multiple windows and a rather cool retro and very realistic Nixie Clock. Regards, Murray Greenman -- Message: 4 Date: Thu, 10 Jun 2010 09:41:00 +0200 From: Magnus Danielson Subject: [time-nuts] HP Z3815A hookup To: Discussion of precise time and frequency measurement Message-ID: <4c10970c.10...@rubidium.dyndns.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Hi! I just got a HP Z3815A but it seems like it is a bit of a challenge to hook it up. I see one large connector for some bus-structure, but don't know the pinning. There is also an 8 coax connector, where I suspect the antenna, 10 MHz, PPS and other generated frequencies pop out. The RS-232 on the front is obvious. I know there is a few SMBs inside, but it would be nice to get some practical hints from people playing with them before. Yes, the hockey-puck is there. 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] Most accurate small crystal
Jim, Getting back to the original question, I'd suggest that the Epson-Toyocom FC-12M would be an appropriate device. See http://ndap3-net.ebz.epson.co.jp/w/www/PDFS/epdoc_qd.nsf/WE_khz_unit/737394E88F20BFBA4925736B002B4C07?OpenDocument. It is a surface mount device, very small, 2 x 1.2 x 0.6mm, and is a true tuning fork, but manufactured using QMEMs (Quartz micro-electro-mechanical, photolithographic techniques). The repeatability achieved by this manufacturing method gives a tightly specified parabolic frequency response (typical of tuning forks) with 25°C turnover temperature. As others have mentioned, there are plenty of strategies around for managing the temperature control of the reference, most achieved by operating the crystal slightly high, and running a pulse swallower driven by a table or other algorithm. Clearly (as is done in the Dallas device) the closer you can associate the temperature sensor with the crystal, the lower the hysteresis and the better the accuracy. Of course a pulse swallower isn't something you'd use for frequency control, but is quite appropriate for time keeping over days and weeks. I have tested the FC-12M in a low power oscillator (I used the Texas LVC1404 oscillator chip and an LM94022 silicon temperature sensor), and it gave very nice results, no dips or jumps over temperature, and reasonable phase noise (although this isn't an issue with RTCs). I modelled the temperature response in EXCEL and it closely followed the 2nd order model. Regards, Murray Greenman -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of time-nuts-requ...@febo.com Sent: Thursday, 27 May 2010 5:31 p.m. To: time-nuts@febo.com Subject: time-nuts Digest, Vol 70, Issue 75 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than "Re: Contents of time-nuts digest..." Today's Topics: 1. Re: For your museum only Loran-C monitor (paul swed) 2. Re: IRIG B (jimlux) 3. Re: Digital tight PLL method (Steve Rooke) 4. Re: Digital tight PLL method (J. L. Trantham) 5. Re: Digital tight PLL method (Bob Camp) 6. Re: IRIG B (Robert Atkinson) 7. Most accurate small crystal (Jim Palfreyman) 8. Re: Most accurate small crystal (Brooke Clarke) -- Message: 1 Date: Wed, 26 May 2010 08:44:16 -0400 From: paul swed Subject: Re: [time-nuts] For your museum only Loran-C monitor To: Discussion of precise time and frequency measurement Message-ID: Content-Type: text/plain; charset=ISO-8859-1 Great ? Have to respond later On Wed, May 26, 2010 at 1:27 AM, Hal Murray wrote: > > paulsw...@gmail.com said: > > Thats why I designed the loran c simulator. It works well. All I need to > do > > is hook it to an antenna and away you go. Maybe a small power amp would > be > > handy. Say 100KW? Antennas the real killer. I think its a zoning problem. > > What's going to happen to that chunk of spectrum? > > How much power/antenna would it take to make a signal that was useful out > to > 1 mile? 100 miles? > > What are the chances the FCC would let amateurs run timing and/or location > services on that band? 1/2 :), but there might be something interesting in > there. > > > > -- > These are my opinions, not necessarily my employer's. 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. > -- Message: 2 Date: Wed, 26 May 2010 06:16:49 -0700 From: jimlux Subject: Re: [time-nuts] IRIG B To: Discussion of precise time and frequency measurement Message-ID: <4bfd1f41.2050...@earthlink.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Bob Camp wrote: > Hi > > Strange as it seems, *stocking* the R's and C's can be an issue. There's also > placement cost. Based on some of the numbers you see, the cross over point > (IC to odd value R's and C's) is amazingly low. I'm not saying any of that's > right, just that it's the way a lot of companies roll up the costs. > > Bob > > Not surprising.. the cost to stock, pick, place, solder is probably the same for a small IC and a
[time-nuts] FEI-5680A holes in the case
I avoided the problem of drilling holes by simply routing the added cables out the back between the cover flange and base. For the RF output I used a short length of the tiniest audio screened cable I could find; for the RS232 I used flat ribbon cable of the smallest dimensions available. 73, Murray ZL1BPU Date: Thu, 01 Apr 2010 20:43:12 -0700 From: "Leigh L. Klotz, Jr WA5ZNU" Subject: Re: [time-nuts] FEI FE-5680A To: Discussion of precise time and frequency measurement Message-ID: <4bb567d0.7030...@wa5znu.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 03/24/2010 03:18 PM, Magnus Danielson wrote: > Fellow time-nuts, > ... > Second, anything I should keep in mind as I power one up? > > ... > Cheers, > Magnus There's a bit of discussion in the archives about the need for a heat sink, and also about the whether it's necessary to anneal the case in a 400C Hydrogen reducing oven after the SMA modification. (Although I do have access to one, it is over the threshold for things I'm willing to do.) Leigh. ___ 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] FE-5680 commands
Magnus, There's also the 'E' command which causes the current operating frequency to be stored for next time it powers up. I've set mine to 10MHz. I too would like to know about any hidden commands. Especially any fine trim commands. On the page www.qsl.net/zl1bpu/PROJ/Ruby.htm there's a list of the currently known commands, a collection of modification information, and also a PC program to download, which controls the FE-5650A and FE-5680A in an easy to use manner, where you dial in the frequency in Hz. These are great little units! Regards, Murray Greenman ZL1BPU --- Message: 8 Date: Wed, 24 Mar 2010 23:18:12 +0100 From: Magnus Danielson Subject: [time-nuts] FEI FE-5680A To: Discussion of precise time and frequency measurement Message-ID: <4baa8fa4.5040...@rubidium.dyndns.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Fellow time-nuts, I am a curious mind, which should come as no big supprise, and I know that lots of people have looked deeply into these devices before me. So, first of all I wonder, what other commands than S and F=<32-bit hex number> is there? Anything fun? Anything useful? Anything booring? Second, anything I should keep in mind as I power one up? Mine came with a little extra-gift. Need to take a photo of that. Very neat. :) Cheers, Magnus -- ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts End of time-nuts Digest, Vol 68, Issue 127 ** ___ 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] Rock, gas, and air
Probably hot air... Murray -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of time-nuts-requ...@febo.com Sent: Monday, 1 March 2010 2:56 p.m. To: time-nuts@febo.com Subject: time-nuts Digest, Vol 68, Issue 3 Send time-nuts mailing list submissions to time-nuts@febo.com To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to time-nuts-requ...@febo.com You can reach the person managing the list at time-nuts-ow...@febo.com When replying, please edit your Subject line so it is more specific than "Re: Contents of time-nuts digest..." Today's Topics: 1. Re: Rock, gas, and air (Bruce Griffiths) 2. Re: Rock, gas, and air (Bill Hawkins) 3. Re: Rock, gas, and air (Stanley Reynolds) 4. Re: DMTD Mixer Terminations (Bob Camp) 5. Re: Rock, gas, and air (Bob Camp) -- Message: 1 Date: Mon, 01 Mar 2010 14:41:20 +1300 From: Bruce Griffiths Subject: Re: [time-nuts] Rock, gas, and air To: Discussion of precise time and frequency measurement Message-ID: <4b8b1b40.8030...@xtra.co.nz> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Bill Hawkins wrote: > Rock I take to be crystal. How about gas and air? > > Bill Hawkins > > -Original Message- > From: Magnus Danielson > Sent: Sunday, February 28, 2010 5:15 PM > To: p...@b737.co.uk; Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] My DIY frequency counter and a request for help > > --%<-- > > I think I have a fairly good setup including bunches of rock, gas and > air clocks alongside a fair set of counters, so I could probably do some > testing, but I am located over in Sweden. > > > Gas = rubidium vapour?? Bruce -- Message: 2 Date: Sun, 28 Feb 2010 19:47:55 -0600 From: "Bill Hawkins" Subject: Re: [time-nuts] Rock, gas, and air To: "'Discussion of precise time and frequency measurement'" Message-ID: <44f1d726cc5f42f99145fe8cb0f3f...@cyrus> Content-Type: text/plain; charset="us-ascii" Whack! (sound of hand hitting forehead) Gas must be Ru and Cs. How do you run your pneumatic clocks? Bill Hawkins -Original Message- From: Bill Hawkins [mailto:b...@iaxs.net] Sent: Sunday, February 28, 2010 7:34 PM To: 'Discussion of precise time and frequency measurement'; 'p...@b737.co.uk' Subject: Rock, gas, and air Rock I take to be crystal. How about gas and air? Bill Hawkins -Original Message- From: Magnus Danielson Sent: Sunday, February 28, 2010 5:15 PM To: p...@b737.co.uk; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] My DIY frequency counter and a request for help --%<-- I think I have a fairly good setup including bunches of rock, gas and air clocks alongside a fair set of counters, so I could probably do some testing, but I am located over in Sweden. -- Message: 3 Date: Sun, 28 Feb 2010 17:50:22 -0800 (PST) From: Stanley Reynolds Subject: Re: [time-nuts] Rock, gas, and air To: Discussion of precise time and frequency measurement Message-ID: <380617.65743...@web30307.mail.mud.yahoo.com> Content-Type: text/plain; charset=iso-8859-1 A while back we had a thread about Paris and a network of air synced clocks ? Stanley - Original Message From: Bruce Griffiths To: Discussion of precise time and frequency measurement Sent: Sun, February 28, 2010 7:41:20 PM Subject: Re: [time-nuts] Rock, gas, and air Bill Hawkins wrote: > Rock I take to be crystal. How about gas and air? > > Bill Hawkins > > -Original Message- > From: Magnus Danielson > Sent: Sunday, February 28, 2010 5:15 PM > To: p...@b737.co.uk; Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] My DIY frequency counter and a request for help > > --%<-- > > I think I have a fairly good setup including bunches of rock, gas and > air clocks alongside a fair set of counters, so I could probably do some > testing, but I am located over in Sweden. > > >? ? Gas = rubidium vapour?? 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. -- Message: 4 Date: Sun, 28 Feb 2010 20:54:53 -0500 From: Bob Camp Subject: Re: [time-nuts] DMTD Mixer Terminations To: Discussion of precise time and frequency measurement Message-ID: <43be29b2-dcb6-43e2-a23b-7ad1deb6b...@rtty.us> Content-Type: text/plain; charset=us-ascii Hi The Minicircuits guys claim 800 to 1000 mv / radian. In my units that would be 5 to 6.2 volts per cycle. I believe I'm getting ~ 3 X that mostly from
[time-nuts] DIY frequency counter help (Gerard PG5G)
Gerard, By now you've no doubt had more offers to assist than you need, and in particular from far more local enthusiasts than me. However, if I can help answer any particular points, I would be pleased to do so. My reason for suggesting this is that I have available a Pendulum CNT-90 counter, plus several very good references, both traceable and high stability (though as you can imagine often not both at once!) I've designed my own counters in the past, but nothing on the scale of yours. Well done! 73, Murray ZL1BPU ___ 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] Double vs single oven TBOLT
Warren, I take the point that you are testing the SAME oscillator as a means of adding some consistency to the test. However, leaving aside this consistency and issues relating to the disciplining device (your TBOLT), I suggest your test of double vs single oven OCXO may be unfair to the single oven device. A well designed high performance single-oven OCXO will include such techniques as ambient compensation and (for example the HP E1938A) incredibly complex high-gain temperature control. As a result, performance can challenge the traditional DOCXO, including temperature slope performance. Your inner-oven only device isn't necessarily a good representative of a single-oven OCXO. While we might expect inner-oven-only to operate like a single-oven 10811A, it may be that the DOCXO inner oven doesn't have the power or thermal gain to handle more than the slight temperature variations (and temp slope) it would see within the outer oven. Try the test again with a single-oven variant 10811A, or with a modern high performance SOCXO such as RAKON STP2602LF. Regards, Murray ZL1BPU ___ 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] 1pps to 10kHz
Ashley, It should be quite easy with any reasonable micro (PIC included) to generate 10kHz using a 1pps reference. My approach would be to operate a software DDS (essentially a numerical oscillator) with a sine-wave look-up table and 8-bit R-2R ladder on an output port. Operate it in the micro's main loop and choose the phase increment value which gets closest to 10kHz. Then all you do is operate a very short interrupt at 1pps which clears the phase accumulator (or sets it to some arbitrary value). Since at 10kHz the multiplication ratio is very low, the reference provided to the micro need not be anything stunning (crystal to 50ppm or cheap TCXO). With a good reference you could make the interrupt operate every n interrupts. I've used this technique successfully for radio transmission at 181kHz using a 2ppm TCXO and AVR micro. See www.qsl.net/zl1bpu/MICRO/EXCITER/Index.htm. Regards, Murray Greenman ___ 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] 64MHz derived from 10MHz
Now I realize I'm known as an injection locking fan, but here's my 2 cents worth: Divide 10MHz by 5 to 2MHz using a Johnson ring counter (74HC4017). Use that to injection lock a 64MHz XO. A low noise solution and no PLLs required. I'd not be surprised if you could injection lock directly with 10MHz. 73, Murray ZL1BPU ___ 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] Injection Locking
Frank, As Bruce suggests, you can in theory lock any rational number ratio, including 11/5 and 21/5. However, the locking gain drops off as the ratio becomes more extreme, and thus the lock range and potential stability are degraded. Yes, you could certainly use a regenerative divider to generate 6MHz or 7MHz, but why not use another IL oscillator? Simply make a 6MHz gate oscillator (common micro crystal) and lock it to 2MHz, divided from 10MHz, then use that to lock 42MHz. If you use Johnson decade counter as divider (e.g. 74HC4017), you get a nice 100ns wide 2MHz pulse to lock to. In my experience locking higher frequencies to lower ones is easier if the reference consists of a pulse with width rather less than the period of the higher frequency, although this depends on how you inject. You'll need to buffer and shape the 6MHz to lock the 42MHz oscillator. Good idea, build a bunch of gate oscillators and experiment. I suggest you also try directly locking 42MHz to 2MHz, in order to determine the lock range. I know from experience at 2MHz to 10MHz (5/1) the lock range is immense, far more than the thermal drift of the 10MHz oscillator, and so I have a very phase stable result. I used mine to GPS lock a 2MHz OCXO, using a micro running at 10MHz, and I injection locked the 10MHz micro clock to the 2MHz, and so needed good phase stability. Not a micro or ASIC in sight! 73, Murray Zl1BPU ___ 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] FW: Injection locking
-Original Message- From: Murray Greenman Sent: Wednesday, 3 February 2010 9:00 a.m. To: 'time-nuts@febo.com' Subject: Injection locking Frank, Bruce's collection would be a good place to start. Thanks Bruce. Most of the examples relate to microwave applications, where often there is no alternative, but the approach works well on HF and VHF as well, and more importantly, can be achieved with existing oscillators with little modification. The IL technique works with ratios from 20:1 to 1:20 or more, and works well with the GPSDO as a reference. My experience is mostly with locking HF crystal oscillators. It works with overtone as well as fundamental oscillators. With an overtone oscillator you can couple into the mode suppression choke. With a tuned tank Pierce oscillator you can couple into the output tank. With a Colpitts, inject into the emitter, collector, or bottom of the crystal. I have made an excellent 10MHz CMOS gate oscillator with 2MHz injection into a varicap acting as one of the crystal load caps (output side). Kit VK2LL and others have used 10MHz injection to lock the 20MHz reference in common Icom HF transceivers. Arguably the father of the Injection Locking technique would be Vasil Uzunoglu, and I have some references for articles by him. The most readable article is "Synchronous Oscillator outperforms the PLL" (from EDN 1999) http://www.edn.com/contents/images/46326.pdf. It shows how to emitter-lock a conventional Colpitts oscillator. The secret here is to get the bias correct. The test and measurement techniques he uses are a good way to assess performance. Robert Adler (inventor of the TV remote!) also explored the IL technique. See: http://www.edn.com/contents/images/46326.pdf US Patent 4,355,404 "Carrier Recovery Network for QPSK Modems employing Synchronized Oscillators", Uzunoglu 1982 US Patent 6,580,330 "Injection Locked Oscillator Automatic Frequency Centering method and Apparatus", Katznelson & Petrovic 2003 (has a good list of background papers to read) "A study of locking oscillators..." Proc IEEE R Adler 1973 http://ieeexplore.ieee.org/iel5/5/31361/31173/01451222.pdf http://en.wikipedia.org/wiki/Injection_locking http://www.amalgamate2000.com/radio-hobbies/radio/synchronous_oscillator .htm http://potol.eecs.berkeley.edu/~jr/research/PDFs/2009-01-ASPDAC-Bhansali -Roychowdhury-GenAdler.pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.130.2535&rep=re p1&type=pdf That should keep you busy for a while! 73, Murray ZL1BPU ___ 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] Low noise PLL for transceiver locking
Frank, My suggestion would be to try injection locking, rather than a PLL. No change is made to the 22MHz and 42MHz oscillators, except to find a way to inject enough reference power to force them to lock to it. Injection locking works well with modest harmonic relationships, and gives good noise performance. The injection can be via a coupling link, or even at the cold end of an existing bypass capacitor. Narrow pulses often work best. I am confident that you could lock 22MHz to a 2MHz injection (divided from your 10MHz reference) if the 2MHz pulse was narrow enough and the 22MHz oscillator sufficiently stable. 42MHz is more of a challenge - you might need a double-step, such as first locking 7MHz to 1MHz from the reference, and using that to lock 42MHz. The literature on injection locked oscillators is quite limited. You get very interesting results as the lock drops out! 73, Murray ZL1BPU ___ 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] Z3815A
Steve, There are at least 20 Z3815A units in ZL Amateur hands that I know of, and many more in VK. They were 'rescued' by a friend in VK, and have been distributed with firmware and manual that we've worked out for them. As far as I can make out, they were not used in cellular systems here. Unlike the Z3801A, Z3805A and Z3816A, the Z3815A is more than just a 'general purpose' unit. It has a complex back plane with all sorts of signals intended for E1/T1 phone systems. Other units I have met with these extra features include the Chongho GPSR-A (clone of the Z3815A), the Samsung GCRU-D and the Trimble (Nortel) NTGS50AA. All came from Australia, and I've no doubt there are several other types there as well. 73, Murray ZL1BPU ___ 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] Z3805A vs Z3815A
Steve, No, I've not seen a Z3805A at all. Not that I know all there is to know about the Z3815A either. 73, Murray ZL1BPU ___ 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] Z3815A vs Z3816A
Alberto, The Z3815A is certainly less common - except down here in VK/ZL. I have one, and can try to answer your questions. The oscillator used in the Z3815A is generally the HP E1938A, although mine is a more recent Symmetricom version with a Milliren 260 OCXO adaptation. Power supply is 20 - 60V, and the units were built under licence by Chongho Industrial in Korea. No official documentation is available yet for the Z3815A, so all I have was achieved by reverse engineering. The unit is compatible with Satstat and Z38XX. I have no experience of the Z3816A, although I have an HP Z3801A, a Samsung GCRU-D and a Trimble NTGS50AA. 73, Murray ZL1BPU ___ 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] EROS Oscillators
EROS is an abbreviation used by the Electronic Research Company. They used to be in Overland Park, KS, USA. They made OCXOs for government and space applications. I have some of their 5MHz devices which were widely used in Transit (pre-GPS) satellite navigation receivers. These OCXOs were fixed (mechanically adjustable) but had very low ageing. The ERC OCXOs typically had "EROS" part numbers. I guess it stands for Electronic Research OScillator? I think the company is now known as Inficon - see http://www.electrodynamics.com/ 73, Murray ZL1BPU ___ 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] FE-5680 frequency change
Rob, It will depend on which version you have. I've not seen a dedicated 15MHz unit, so can't be sure which synthesis scheme it uses. If it has a dedicated fixed synthesizer, you may be out of luck. However, if (like the 1pps models) it has a DDS synthesizer, the frequency change can be done via a serial command. For details see: http://www.mail-archive.com/time-nuts@febo.com/msg13486.html http://www.leapsecond.com/museum/fei5650a/ http://www.qsl.net/zl1bpu/PRECISION/FE-5650A.htm The DDS board can be identified by comparing it with the photo at: http://www.leapsecond.com/museum/fei5650a/freq_divider.jpg Bear in mind that the photo might be the other way around from the angle you get to view it at. If you have the DDS version (it's the same in the FE-5650A and FE-5680A), you're in luck, and can program any frequency from DC to 20MHz or so. You might consider buying another dedicated unit for 2.048MHz. Bob Mokia (NHBBob on Ebay) has the 1pps versions for sale, and these are easily converted to remote frequency programming, as described in the links above. Regards, Murray Greenman ___ 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] Morion MV89
John, Yes, the temperature and current are completely normal. I have my MV89 running on the bench here, and it's drawing 300mA and too hot to hold. Don't think about lagging it to keep it warm, or adding cooling, as you'll mess up the internal thermal profile, and then the calibration and performance may suffer. The ageing rate of my unit is about -2e-10/day. Murray ___ 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] Time running backwards down under
Think about it... no it doesn't. Just takes a while to get used to the sun being on the wrong side and the moon being upside down (think about that one!). And yes, the water goes down the plug hole the other way, and hurricanes rotate the other way. However, here in New Zealand we are currently 13 hours ahead of UTC, so well ahead of the rest of the world! Murray ___ 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] Down under Time Nuts
Ray, There are several of us down here on the list. I can think of several in AU and at least three or four in NZ. If they don't identify themselves to you, let me know. We also know the whereabouts of some nice gear. Regards, Murray Greenman ZL1BPU www.qsl.net/zl1bpu ___ 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] Lifetime of Rb references
I've not found this to be a problem. I simply turn mine on 5 minutes before I need it. If it was necessary to run it for weeks, I'd find a way to use an OCXO or GPSDO instead. It's a bit different with the old-style Rb References such as the HP 5065A, which take longer to get going. Mine has been running more or less continuously since 1978, and while other things have died along the way, it hasn't run out of tube life yet. Murray ZL1BPU ___ 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] Calibration of Rb
Someone asked what the Time-Nuts way of calibrating a Rb source would be. I'm no expert, but here's my 2c worth: I don't like making adjustments, as they can lead to lowered reliability, lowered understanding of the processes of ageing, and are also more work. As someone else pointed out, provided you know where your oscillator is, it is stability that is important, not accuracy, so to me, calibration is a matter of MEASUREMENT AND DOCUMENTATION, not twiddling of knobs. I keep records of all my oscillators, without adjusting any, and so have a very clear idea of their ageing rate, and can thus predict with confidence where they will be without necessarily measuring on a daily basis. For example, I know my Morion MV89 is currently at 10.00271MHz, going up at 2.6e-10/day, and my HP E1938A is at 9.98082MHz, going down at 8.7e-10/day. As a reference I use a Samsung GCRU-D GPS Discplined Reference, and make measurements with a Pendulum CNT-90 counter. I borrow the counter from work when I need it, as my own HP 5315A counter lacks the resolution. As a matter of interest, the OCXO in the Samsung (which is a C-MAC STP2145A) has been under my eagle eye for two years now, and has an estimated rate of -2e-9/year, incredibly low, but probably just dumb luck. Because it is GPS locked, this is estimated from the going rate of the EFC voltage and the known Kvco of the OCXO. Regards, Murray ZL1BPU ___ 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] Newbie question - what use is a Ruby?
Joseph, There are several uses for a Rb unit (even if you already have a GPSDO). 1. The Rb unit is very portable, and is on frequency from cold in 5 minutes. Great for tests away from home. Easily battery operated. No GPS antenna required either! 2. With fast warm-up, they are ideal as a reference for gear you don't use too often, and can't justify the power consumption (or added space) of a GPSDO and its backup supply, which must run continuously. 3. Some units (such as the FEI FE-5650A and FE-5680A) are frequency programmable, and so you can use them as a stable signal generator or (if you're a Radio Amateur) as an Exciter for experiments. I have software which can transmit an on/off or frequency shifted pattern for ID purposes. 4. They are a handy adjunct to the GPSDO. Use the latter to calibrate the former, and then you've a reference even if GPS is unavailable. The Rb units also have very good short-term stability. 5. If you are interested in making phase noise or frequency measurements requiring a mix-down technique, the programmability of the FEI units is very useful. Phase noise is good enough for most applications. I have two units (FE-5650A and FE-5680A), from China. They started life providing only 1pps (1Hz) and required reasonably simple modification to provide 1kHz to 15MHz operation in ~10mHz steps. When thus modified, the output level is about +9dBm. The units use a 50.255MHz oscillator in the physics package, and this acts as reference for a built-in DDS synthesizer, hence the frequency flexibility. Disadvantages? 1. You can have any frequency you like, but only one with sub-ppb accuracy (because of the DDS step size). 2. The power consumption (not that it's as high as the GPSDO). 3. Ageing, and the need for occasional calibration. Regards, Murray Greenman ___ 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] Morion MV89
I have an MV89, and it draws about 320mA steady state. No cycling of the current at all once warmed up. The surface temperature is warm, but you can leave your hand on it. Performance wise, the MV89 is very good. The ageing is particularly low - after only a week from power-up it's running at under 1e-9/day. By the way, my unit came direct from Russia, not epay. 73, Murray ZL1BPU ___ 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] High accuracy? GPS position
Mark, How do you KNOW your position to such accuracy? Is it in fact possible to survey your position to that accuracy by any independent means? If, for example, you use official survey marks to determine your position by direct measurement, are the survey marks really that accurate? Murray ___ 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] Gravity and OCXOs
Rick is right. The effect you see when turning your GPSDO upside down will be predominantly the direct gravitational effect on the OCXO crystal and its mountings. You see this with any OCXO, and the good ones will have a '2G turnover' or other G rating quoted. For example, the well known HP 10811A specification says 'Gravitational Field: <4 x 10^-9 for 2g static shift (turnover). That's fairly typical. I just measured the effect on a good C-MAC 10MHz OCXO (similar to those used in many recent GPSDOs) and measured 40mHz p-p, or exactly 4e-9. It's complicated in the GPSDO because the correction mechanism (via GPS 1pps) is much slower than the rate at which you can change the gravitational effect. Rb references simply have a faster loop and will correct the G effect more quickly. Murray ___ 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] Generating 66.666...MHz from 10MHz
Here's an idea which actually works (I tried it). Rather than lock at 10MHz, you lock directly to 1pps. You can lock an XO to 1/3 Hz steps by locking to 1pps and ignoring two out of three results from the TIC. I did it at 7.333MHz, using an AT90S2313 micro, and you could just as easily do it at 8.333... and then multiply by 8. Yes, it does leave you with a very low loop frequency! Although I've not tried it, you could potentially add 120 degrees equivalent to one intermediate TIC result and subtract 120 degrees from the next, and so lock at 1Hz. 73, Murray ZL1BPU ___ 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] Long Wave Receiver ideas
Poul, Regarding Clicklock. Yes, in a sense Clicklock is a lock-in amplifier. However the really special thing is that it completely compensates (within reason) for the drift in ALL the oscillators in your receiver and/or converter, so that it becomes GPS locked. It does this by comparing the phase of harmonics of 1pps as they arrive at the receiver with the phase of the 1pps itself. It uses an NCO to down-convert to zero Hz. There is obviously an advancing phase with frequency in the 1pps harmonics if the down-converted frequency is high, and the NCO is shifted to compensate. It will also therefore also compensate for changes in phase and delay through the preamp, feedline and receiver filters. If you look at the examples on the reference I gave, http://www.qsl.net/zl1bpu/ZL2AFP/CLICK/click.htm, you'll see there's a phase plot which shows the integration of I and Q samples, plus phase and power plots which are achieved by maths from the I and Q followed by 'leaky integrators'. That bit was my contribution. The whole idea originated with Peter G3PLX, the source of many good ideas. Give it a try - it's quite a tricky bit of software to drive. Regards, Murray Greenman ZL1BPU ___ 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] Long wave receiver ideas
Marc, I endorse Leigh's suggestion. It is a very simple but effective solution. I use the SA602 myself. Used with an active whip antenna sensitivity is not a problem, and you can receive signals from around the world. As for the local oscillator, yes you can most certainly use the FE-5650A or FE-5680A, but I don't think that's necessary. If you have a receiver which has suitable stability and can receive 10MHz, then a very good solution is to drive the S602 with a 10MHz OCXO as the LO (the SA602 is very accommodating, and can act as VFO, XO or buffer for an external LO), or even drive it from a 10MHz GPSDO. Bear in mind that any phase noise or modulation will appear on the mixed output (and 1Hz modulation can be a problem with GPSDOs if you're not careful). There is a very neat technique which works well below about 500kHz to give extreme precision to reception. This is 'Clicklock' developed by Peter Martinez G3PLX. Essentially you can receive any signal which has ultra-low drift even if your receiver or converter has drift. It uses harmonics of a 1pps reference compared with the 1pps pulse itself to compensate for receiver drift, and all you need is a 1pps GPS signal and a PC with sound card. The software is then able to provide sufficient phase stability to integrate the received signal synchronously over many seconds, giving incredible sensitivity and bandwidths measured in milliHz. It has enabled me to discern the carrier (and hourly phase advance) of WWVB on 60kHz at a range of 8000km, and for my own 80uW EIRP transmission on 181kHz to be detected 500km away. See http://www.qsl.net/zl1bpu/ZL2AFP/CLICK/click.htm for more information and Clicklock software by Con Wassilief ZL2AFP. 73, Murray Greenman ZL1BPU ___ 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] Lady Heather question
John/Mark, I don't own a Thunderbolt, but I do have a very nice Trimble NTGS50AA GPSDO which works very well, and it also operates very nicely with TBOLTMON, in both TSIP and SCPI modes. However, I've just fired up Lady Heather V2.0 for the first time, and although the program starts, nothing happens. I have a graph graticule at the bottom, and a blank black area above with just a few things written on it, such as the graph legend. No sign of the wealth of data shown in the help file screen shot, nor any graph data, even after waiting quite a while. I tried both the Win version and the DOS version, and they behave the same. My test computer is an old IBM Aptiva with 450MHz 586 processor, running Win XP. I use COM2 and the program seems happy with that, and everything works fine with TBOLTMON. My next step is to drag out a laptop and spy on the comms between the computer and GPSDO to see what's going on (if anything). I know this is a big ask, but any suggestions as to what might be happening? 73, Murray ZL1BPU ___ 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] FE-5680A heat sink
I think we've all learned from this. Good info about the Efratom unit, and sounds as though we should aim for around 38C with the FEI units as well. The FE-5680 looks to be easier to deal with than the FE-5650, so I'll look into that first. Murray ZL1BPU ___ 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] FE-5680A thermal management
Leigh, I agree with Chuck. I have both an FE-5650A and an FE-5680A. With the former I was concerned about the heat, and so ran it only for short periods, until I understood what was going on. I had the impression from the data sheet that there were different heatsink options for different temperature ranges, and I now believe this led me astray. With the FE-5680A I had the opportunity to study things in more detail. There is no temperature range specification that I could find, and no particular advice in the manual regarding installation. I ran the unit from regulated 15V DC, and monitored the supply current. With no extra cooling, the steady state current was about 700mA. With air blown over it, the current increased. With the unit placed in a poly bag, the current decreased to about 650mA. By the way, the current also decreased when operated from 17V DC. This tells me that the whole structure is part of the thermal package, and we should not attempt to force down the case temperature just because the unit runs hot. My experience with high performance OCXOs tells me that the thermal environment is carefully designed, and part of the calibration process - if you modify this environment (by cooling or extra insulation) you modify the thermal environment, and are at risk of modifying the performance. I'd leave well alone, and run the unit in an open, breeze-free environment. 73, Murray ZL1BPU ___ 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] Msg to N.Z. time nuts re time pips
Geoff, I'm not in a position to check at present, but have also noticed discrepancies in the time pips in the past. I'd not use a GPS receiver for this, as they can easily indicate a second or so out. I use a GPS Disciplined Receiver (HP Z3801A or Trimble NTGS50AA) for the job. I suggest you talk to Dr Tim Armstrong (t.armstr...@irl.cri.nz). He's the guy who looks after the official NZ time service, which is the source of those time pips. The equipment is at Gracefield in a room with three Caesium standards. He should be able to explain how the time pips are distributed, and you may find (if you encourage him a little!) that he is also interested in measuring their delivered accuracy as well. Regards, Murray ZL1BPU ___ 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] Wrong date on Samsung GCRU-D
My Samsung GPSDO is a very good and fairly new unit, but I've just spotted that the date it is reporting is incorrect! It should be 1 March, but it is reporting 29 Feb, and there isn't one this year. The GPS module I'm also running at present (u-BLOX Antaris) does report the date correctly. 73, Murray ZL1BPU ___ 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] Trimble GPSTM
Chris - Which model Trimble do you mean? I have a Trimble NTGS50AA, built for the Nortel Metrocell system. It talks TSIP, although its native language is (poorly understood) SCPI. The NTGS50AA works fine with TBOLTMON. Regards, Murray Greenman ZL1BPU ___ 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] Roof-mount GPS antenna
Down here in NZ, a common form of TV antenna mount is the 'hockey stick', which is a J-shaped pole with a plate for barge-board or gable mount (on a vertical surface) and a vertical pipe about 1m long and 20mm diameter. A typical pipe-mount GPS antenna is easy to mount on this, either directly threaded on, or clamped to the side with a U-bolt. The threaded on connection is really tidy if you have the right antenna, as the cable can go down through the pipe. Another way to do pipe-mount is to strap a short length of suitable pipe to a roof vent or chimney, but you'll have to be creative with where to bring the cable in - perhaps over the edge of the roof, provide a drip curve, then under the roof through the soffit or gable end and across the attic and through the ceiling. Sewer pipe vents are good candidates. Chimneys less so, unless they are unused. I once used a hockey-puck magnetic mount type antenna on a small metal plate, and chocked the plate horizontal on the sloping (metal) roof using a block of wood. It worked fine, but had the bad habit of blowing away in a storm, even when I weighted the plate down with bricks. Look for TV hardware in your nearest DSE/Jaycar/Tandy/hardware store. 73, Murray ZL1BPU ___ 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] Indoor GPS for GPSDO
You might as well forget using an indoor antenna for GPSDO use. For best performance, you need an antenna which sees the top of the sky (say down to 30° elevation) really clearly, and ideally you want an antenna designed for timing applications, which favours high angle satellites. This is quite different to navigation use, where low angle satellites give better angular calculations. I'd say if you can't achieve 24 hours without a holdover event, you need to improve the antenna. How long it takes to perform the survey is another matter, and seems to depend on the GPSDO. I've experience with some of the hot new receivers (such as the ublox LEA-5) with good indoor navigation performance, but even with this type, I would not expect the timing to be perfect without a good antenna in a good location. You should also be able to achieve 7 - 8 satellites in the fix most of the time, with at least 40dB average CNR. My Samsung GCRU-D achieves these figures with no difficulty using a Novatel GPS-600 antenna and 30m of cable. Performance of my Trimble NTGS50AA is also similar, on a commercial hockey-puck designed for timing reception. The HP Z3801 has only a 6-ch receiver, and on an old Furuno marine quadrifilar antenna (designed for navigation) performs less well, and I have short holdover events every few days. All antennas have a clear view of the top of the sky. 73, Murray ZL1BPU ___ 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] Coddling your TBOLT
Personally, I'd just leave the TBOLT to get on with the job. It's probably a good idea to exclude draughts, but adding further insulation will probably not help matters and may hinder them. I'm thinking specifically of what happens to the ambient compensation of OCXOs when the insulation thermal resistance (and thus the thermal gradient to ambient) differs materially from when the unit was calibrated. Murray ZL1BPU ___ 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] Tek 602
Magnus, I can't help you with the manual, but I agree, it will be useful for T&F applications. I have a newer model X-Y display (the one with storage, forget the model) which I intend to use for T&F. By the way, for anyone who is wondering, a conventional TV Vectorscope works great as a phase comparator for T&F, provided your reference frequency is suitable. I have the PAL model (4.433MHz colour subcarrier), and it works fine at 5MHz. I feed 0dBm 5MHz reference into the subcarrier input, and any other 5MHz signal for phase comparison in one of the video inputs. You get a dot on the screen which rotates with phase, and it's easy to see phase jitter and changes as small as a couple of ns. Regards, Murray ZL1BPU ___ 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] STLN4096A / HP Z3817
Skip, How about sending me some photos of the unit? I know the Z3815A and E1938A well, and if it's the same in different packaging, I'll be able to tell. 73, Murray ZL1BPU ___ 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.
