Re: [time-nuts] FCC politics vs their engineers...
I remember a story told to me many years ago, about a discussion between an American Astronaut and a Russian Cosmonaut. It goes along something like this... Astronaut to Cosmonaut: I wouldn't be happy sitting on the top of that low technology rocket Cosmonaut to Astronaut: I would rather that than sit at the top of a pile of low bids Rob K -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of J. Forster Sent: 17 September 2013 19:19 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] FCC politics vs their engineers... It is hard to imagine a more stupid or more dangerous way of making decisions than by putting those decisions in the hands of people who pay no price for being wrong. - Thomas Sowell YMMV, -John === Was it not always so?? Remember the politicians pay the bills not the engineers! Alan G3NYK - Original Message - From: Eric Williams wd6...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, September 17, 2013 7:04 PM Subject: Re: [time-nuts] FCC politics vs their engineers... He tells me with some bitterness that politics triumphed over all of the objections of the engineering staff to LS and that this is not the first time that this has happened. That's how we ended up with Challenger and Columbia. On Tue, Sep 17, 2013 at 6:46 AM, Michael Baker mp...@clanbaker.org wrote: Time-Nutters-- Jim wrote: snip That's why the FCC granted a conditional waiver of the rules. It was politically expedient, and I would imagine that the engineers at the FCC thought there's no way they'll be able to demonstrate no interference Charles wrote: snip The Commission not only thought LS would demonstrate non-interference, it put its thumb on the scale until the public outcry became too loud to ignore (the GPS interests took forever to wake up -- that didn't happen until all of the comment periods were long closed). It just didn't matter what the staff engineers thought -- which is business as usual at the FCC. --**-- A friend of mine was one of the FCC lead supervisory engineers that was involved in the LS fiasco. He tells me that there were technical reports, evaluation summaries and strong opinions offered by the engineering staff that provided a number of reasons why the LS project should be denied. He tells me that most of these engineering studies got buried and ignored. He tells me with some bitterness that politics triumphed over all of the objections of the engineering staff to LS and that this is not the first time that this has happened. Mike Baker Gainesville, FL USA __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/list info/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] My FE-5680A Came In Today
Hi If you re-tune the Rb, the already divided down output on the pps will be at a really odd rate. You can use it, but unwrapping the phase is going to be interesting (= it will wrap a lot). There are other ways to do things. One is to synthesize a highly accurate 100Hz off of the Rb output. That's going to require some dividers. You also get into the multiple phase wrap issue quicker than with a pps. Bob On Sep 17, 2013, at 9:07 PM, Bob Stewart b...@evoria.net wrote: D'oh! But is there a way I can run for let's say 200 pulses on the B channel and see the count on the A channel? From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, September 17, 2013 7:54 PM Subject: Re: [time-nuts] My FE-5680A Came In Today Hi For checking things like GPSDO's the pps is actually much more useful than the 10 MHz. Just do the count one to the other trick and you have a very good way to test what's going on. In it's normal configuration it should tune to within about 1 ppt of the proper frequency. That would be 10,000,000 Hz / 1,000,000,000,000 or 1 ns every thousand seconds on the pps. Bob On Sep 17, 2013, at 8:37 PM, Bob Stewart b...@evoria.net wrote: Hi, I'm just looking for an accurate standard for my GSPDO PLL coding. As it is, I've been depending on others who have these to tell me the code works. I understand that when these are retuned to 10MHz, they're .005Hz off due to the DDS. I'm good with that. =) Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, September 17, 2013 7:30 PM Subject: Re: [time-nuts] My FE-5680A Came In Today Hi Keep in mind that these things make a pretty awful 10 MHz standard. They are spur monsters in a big way. They won't drive your counter nuts, but for anything that wants signal purity - watch out. Bob On Sep 17, 2013, at 8:14 PM, Bob Stewart b...@evoria.net wrote: Hi Bob, Yeah, I figured that retuning it would lose the 1PPS. No biggie. There are a number of those little connectors in this device, and the two that have cables connected use a flat 90 degree connector with a coax that's a bit smaller than RG-174. I just want to snap a pigtail on it and lead it out through a notch in the cover where the DB-9 connector is. There are several examples on the web where people solder wires to the connector and to the RS-232 header. I'd just as soon avoid soldering wires if I can. Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Tuesday, September 17, 2013 7:06 PM Subject: Re: [time-nuts] My FE-5680A Came In Today Hi If you retune it, you probably will throw off the pps. The pps drive strength is a bit weak, so you need to be careful looking for it. On some units there is a software command to enable / disable it (as in pps only when warmed up and locked - like a gps). The can / cover on the unit is mu metal (Rb's are mag sensitive). If you drill a hole in it, you are likely to impact it's mag shielding properties. Bob On Sep 17, 2013, at 6:21 PM, Bob Stewart b...@evoria.net wrote: My FE-5680A Rb standard came in today. After the usual inspections etc, I fired it up and I have the purple haze. The native output is 8.38860798/9 (last digit jitter) as read on my 5335A using my GPSDO as an external standard. I've got a ways to go before it's all setup, but this is looking good. Does it warmup and change frequency at all, or can I retune it to 10MHz and use it as a reference without any further ado? Can someone tell me what type of socket that is where you tap off the RF? It looks sort of like a uFL connector, but a bit bigger. I'd rather avoid hacking and soldering on this if I can. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New NTBW50AA
Moved antenna to fence line on a 10' emt. Nothing much seems to change no matter what I do, so I guess this is what I'm locked into unless I start getting carried away. I still get generally about a 400 ppt swing with the OSC, about 20 ns swing with the PPS and the other things are just what they are. Different filters and surveys don't seem to change anything that I've seen. I like the antenna better at the fence. but I had to add another 30' of RG-6. I have about 100' of FSJ4-50B that I have no use for right now, but I doubt that will do anything for me. http://i251.photobucket.com/albums/gg287/DogTi/time/20139-181346_zps31fb89be.jpg Is this acceptable? From what I deduce, I can expect to get accuracy of +-0.2 Hz at 1GHz? I was hoping for another decimal. This should be plenty good to get mHz accuracy at 100 MHz if I can even measure that using SpecLab. Seems to me Arthur was getting much smaller swings on his ppt with his older Nortel. I did figure out the temp thing and found a link where it's explained, but I have a new chip coming and expect to change it, but I doubt if anything will change except the reported temp will most likely track to less than 1° C unlike it's doing now. Would it be worth looking into the MV89A OCXO as a replacement to get better ppt? I haven't done any looking into my OCXO yet to see what it's spec sheet may be. Still waiting on a chip inductor that I messed up in the TS-2000 so I can get the XRef working. Dave N3DT ___ time-nuts mailing 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] New NTBW50AA
I still get generally about a 400 ppt swing with the OSC, about 20 ns swing with the PPS and the other things are just what they are. Different filters and surveys don't seem to change anything that I've seen. * * * Is this acceptable? You seem to have a reasonably decent view of the sky, judging by the numbers of satellites you are able to track, but the signal quality is lower than I expect (note: my only Trimble GPSDO experience is with TBolts). I'd expect the signal reports to be mostly from 40 dBc upwards, while yours run from low 30s to barely 40 (IIRC, this hasn't changed materially as you've moved the antenna multiple times). Your results look consistent with those signal readings. I don't recall -- have you tried a different antenna? It's also possible that the front end in that particular GPS is noisier than the TBolts I'm familiar with. Also, I see that the oscillator loop gain is set for 1.4 Hz/v. I have no idea what is normal for the OCXOs used in that unit. Have you verified this yourself? (Turn disciplining off, then manually run the DAC voltage up and down while watching the frequency on a counter.) Lowering the GPSDO loop gain may improve matters. Or not. (IIRC, this may mean setting gain to a higher number -- the gain does not SET the loop gain at that value, it tells the digital loop expect the oscillator to have this EFC characteristic.) I did figure out the temp thing and found a link where it's explained, but I have a new chip coming and expect to change it, but I doubt if anything will change except the reported temp will most likely track to less than 1° C unlike it's doing now. That would be my expectation, too. Would it be worth looking into the MV89A OCXO as a replacement to get better ppt? I haven't done any looking into my OCXO yet to see what it's spec sheet may be. That depends on whether or not the remaining errors you are seeing are attributable to the oscillator. The remaining errors can be classed broadly as (i) noisy/wandering OCXO, and (ii) adjustments to the DAC that the GPS thinks it should make. In your case, they look more like class (ii) than class (i) to me. Before you switch out the OXCO, let the crystal that is in the unit now settle down for a few months of uninterrupted running. The class (i) errors should go down by themselves. If the errors you see do not go down, it is more evidence that your limitation is noise in the GPS, not the OCXO. Best regards, Charles ___ time-nuts mailing 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] New NTBW50AA
Thanks Charles, I have tried the a command and that is where LH put the numbers, TC from 100 to 500, Damp from 1.2 (that's how it came) to 1.0, and it changed the gain from 1.2 to 1.403. I could certainly try playing with the DAC voltage. I haven't written anything to the prom yet, I think, when I turn the unit off and back on it seems to revert to where it was when I got it, but that's only been a few times and for a few minutes, it's been on nearly since I got the antenna installed on Sep 9, or 9 days. I haven't done a precision survey at this location either, but it didn't seem to make any difference at the other locations. As far as dBc, I've seen numbers in the 50's at this location and I don't think I've seen that before, but nothing scientific about any of the locations or numbers. This location sees to the east and west probably better than the others, south should be about the same. Actually right now I'm seeing 2 in the 60's and one at 71.5. I wasn't going to change the OCXO willy-nilly, I'll have to explore this one first. I'll see if I can find any info on this OCXO. The antenna is a Lucent PCTEL GPS-TMG-HR-26N, High Rejection 26dB With Enhanced Narrow Band Filtering, apparently for high RF environments, only one I've got or tried, it came with the Nortel from RDR. About 130' of RG-6 and with the 26dB gain and a 4 dB noise figure, it's probably swamping any loss in the cable or NF of the RX. You didn't say, but I get the feeling maybe I should be getting smaller ppt numbers? When you say noisy, is high ppt generally a result of excess noise (front end NF)? When I get a chance I'll play with the DAC voltage. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Decent GPS Antenna Active/PassiveRecommendation
Hi Dave, Hopefully not too far off topic, just wanted to chime in here. I have known the people at RDR Electronics (I live in NY and am not affiliated with them) for over 15 years. I used to live in the Denver area and got to know the original owners. They used to buy industrial aerospace surplus cheap and turn it around quick. They are like us in that they like to tinker around with equipment (many times much more expensive than most of us could afford). They have respect for us time nuts ;). I have never known them to not stand by something they sold. They do sell direct outside of auctions - just look them up online in the Denver area. They are easy to talk to and nice people. If you are wondering how many items they may have, ask them. They are not trying to hide anything. They do need to turn a profit like any company. I am ready to spend $1000 + on an item soon and I would not flinch at giving it to them. They do answer their emails and will listen to you if you are looking for a special setup for a good price. They occasionally come across a one of a kind oddball item and would sell direct rather than post on an auction. My only concern I have ever heard was from outside the U.S. They have to turn stuff around fast and can't take on the risk of issues with international shipments from what I have heard. Sorry for what sounds like a commercial. I really have no current connection, but wanted to let you know what you could expect. On Sun, Sep 15, 2013 at 10:34 PM, quartz55 quart...@hughes.net wrote: I got the Lucent 26dB antenna with my Nortel and it seems fine, although I have nothing to compare it to. It seems like a fine commercial unit and comes with the protector mount. I don't know what RDR bids are running up to, but at $30 plus $11 shipping, you might as well buy the whole Nortel GPSTM and the antenna for $150 delivered. He doesn't let on how many of either he has. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Decent GPS Antenna Active/PassiveRecommendation
Gerald, I wasn't trying to make any derogatory remarks about RGR. I did email him about the Nortel unit I got and he responded quickly with an appropriate answer, so my dealings with them have been fine. I actually bought some other stuff from him after the GPS unit. I'm happy with what I've gotten from them. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] GPSDO vs Rb standard
I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Hi One cycle of 10 MHz would be 100 ns. 100 ns per second would be 100 ppb. 100ns per 20 seconds would indeed be 5 ppb. Since the Rb is *stable* but not *accurate*, the real question is - how much does the 5 ppb change by? The Rb can't tell you if the GPSDO is correct. The best it can do is tell you if it changed. If you can demonstrate that the GPSDO is locked up, and that it's stable for many days, you can reasonably conclude that the GPSDO is accurate. I'd say the first step is to get the Rb tuned closer to the GPSDO. You should be looking for 0.01 ppb changes. That's going to be tough with a 5 ppb offset. Bob On Sep 18, 2013, at 5:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Decent GPS Antenna Active/PassiveRecommendation
Oh - sorry - did not mean it that way. I wants to let you know you can talk to them and they will work with you (and sometimes get a better deal if you write a check and can wait ). Glad to see what you have done - I am just starting back in the precise time work, but I used to work in USAF with precise time with Loran C. Guess that is gone (for now :) ). Jerry On Wed, Sep 18, 2013 at 5:24 PM, quartz55 quart...@hughes.net wrote: Gerald, I wasn't trying to make any derogatory remarks about RGR. I did email him about the Nortel unit I got and he responded quickly with an appropriate answer, so my dealings with them have been fine. I actually bought some other stuff from him after the GPS unit. I'm happy with what I've gotten from them. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Hi Bob, As always, thanks for your informed help. I had been reaching the same conclusion, but needed unbiased confirmation. I think the RUBY4 software does what I want? I'll look into it. Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 5:01 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi One cycle of 10 MHz would be 100 ns. 100 ns per second would be 100 ppb. 100ns per 20 seconds would indeed be 5 ppb. Since the Rb is *stable* but not *accurate*, the real question is - how much does the 5 ppb change by? The Rb can't tell you if the GPSDO is correct. The best it can do is tell you if it changed. If you can demonstrate that the GPSDO is locked up, and that it's stable for many days, you can reasonably conclude that the GPSDO is accurate. I'd say the first step is to get the Rb tuned closer to the GPSDO. You should be looking for 0.01 ppb changes. That's going to be tough with a 5 ppb offset. Bob On Sep 18, 2013, at 5:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you will find out that the Rb is slow... you can also check the Rb's PPS against the GPS's PPS. On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I imagine this is in the specs of the specific receiver - but I was wondering if some of you have actually measured what that is - and could report the numbers that you have found. Thanks! John Westmoreland On Wed, Sep 18, 2013 at 3:07 PM, Azelio Boriani azelio.bori...@screen.itwrote: Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you will find out that the Rb is slow... you can also check the Rb's PPS against the GPS's PPS. On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Hi John and Azelio, The problem with the GPS 1PPS is the +/- 52ns sawtooth. Without some magic hardware, you're left with using a stable 1PPS and then calibrating that to the correct frequency. If my software does what my math says it does, then my OCXO is very close to correct. Testing is time consuming to say the least. Bob From: John C. Westmoreland, P.E. j...@westmorelandengineering.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 6:13 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I imagine this is in the specs of the specific receiver - but I was wondering if some of you have actually measured what that is - and could report the numbers that you have found. Thanks! John Westmoreland On Wed, Sep 18, 2013 at 3:07 PM, Azelio Boriani azelio.bori...@screen.itwrote: Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you will find out that the Rb is slow... you can also check the Rb's PPS against the GPS's PPS. On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
The GPS's PPS wanders but it can be used to have an idea whether your Rb is fast or slow. How much the wander will be, depends on the type of GPS receiver, the antenna position and the survey, the GPS clock granularity (the sawtooth). Given a suitable amount of time (5 minutes, for example) you can see if the Rb PPS is fast or slow. I have measured up to 200nS of PPS peak-to-peak wander using a Z3815A as a reference. On Thu, Sep 19, 2013 at 1:37 AM, Bob Stewart b...@evoria.net wrote: Hi John and Azelio, The problem with the GPS 1PPS is the +/- 52ns sawtooth. Without some magic hardware, you're left with using a stable 1PPS and then calibrating that to the correct frequency. If my software does what my math says it does, then my OCXO is very close to correct. Testing is time consuming to say the least. Bob From: John C. Westmoreland, P.E. j...@westmorelandengineering.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 6:13 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I imagine this is in the specs of the specific receiver - but I was wondering if some of you have actually measured what that is - and could report the numbers that you have found. Thanks! John Westmoreland On Wed, Sep 18, 2013 at 3:07 PM, Azelio Boriani azelio.bori...@screen.itwrote: Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you will find out that the Rb is slow... you can also check the Rb's PPS against the GPS's PPS. On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Hi The Rb's have a couple of issues: 1) Its been years since they were set on frequency and they do have a yearly drift rate 2) They have a temperature coefficient of drift that may be fairly large (0.1 ppb over -30 to +70) 3) They self heat quite a bit, so they do move temperature / need a heatsink The solution to the temperature issue is a servo controlled fan. The solution to the first drift / accuracy issue is to calibrate them against something else. Bob On Sep 18, 2013, at 7:13 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I imagine this is in the specs of the specific receiver - but I was wondering if some of you have actually measured what that is - and could report the numbers that you have found. Thanks! John Westmoreland On Wed, Sep 18, 2013 at 3:07 PM, Azelio Boriani azelio.bori...@screen.itwrote: Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you will find out that the Rb is slow... you can also check the Rb's PPS against the GPS's PPS. On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Hi The purpose here is to estimate the stability of a GPSDO. For that, you don't need perfect. You simply need to get the Rb close enough that it's error is manageable. Bob On Sep 18, 2013, at 8:18 PM, Azelio Boriani azelio.bori...@screen.it wrote: The GPS's PPS wanders but it can be used to have an idea whether your Rb is fast or slow. How much the wander will be, depends on the type of GPS receiver, the antenna position and the survey, the GPS clock granularity (the sawtooth). Given a suitable amount of time (5 minutes, for example) you can see if the Rb PPS is fast or slow. I have measured up to 200nS of PPS peak-to-peak wander using a Z3815A as a reference. On Thu, Sep 19, 2013 at 1:37 AM, Bob Stewart b...@evoria.net wrote: Hi John and Azelio, The problem with the GPS 1PPS is the +/- 52ns sawtooth. Without some magic hardware, you're left with using a stable 1PPS and then calibrating that to the correct frequency. If my software does what my math says it does, then my OCXO is very close to correct. Testing is time consuming to say the least. Bob From: John C. Westmoreland, P.E. j...@westmorelandengineering.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 6:13 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I imagine this is in the specs of the specific receiver - but I was wondering if some of you have actually measured what that is - and could report the numbers that you have found. Thanks! John Westmoreland On Wed, Sep 18, 2013 at 3:07 PM, Azelio Boriani azelio.bori...@screen.itwrote: Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you will find out that the Rb is slow... you can also check the Rb's PPS against the GPS's PPS. On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Hi When I want to tune an Rb, I just hook up to it with a terminal program and hack away at it. There's not a lot to the protocol. Bob On Sep 18, 2013, at 6:49 PM, Bob Stewart b...@evoria.net wrote: Hi Bob, As always, thanks for your informed help. I had been reaching the same conclusion, but needed unbiased confirmation. I think the RUBY4 software does what I want? I'll look into it. Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 5:01 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi One cycle of 10 MHz would be 100 ns. 100 ns per second would be 100 ppb. 100ns per 20 seconds would indeed be 5 ppb. Since the Rb is *stable* but not *accurate*, the real question is - how much does the 5 ppb change by? The Rb can't tell you if the GPSDO is correct. The best it can do is tell you if it changed. If you can demonstrate that the GPSDO is locked up, and that it's stable for many days, you can reasonably conclude that the GPSDO is accurate. I'd say the first step is to get the Rb tuned closer to the GPSDO. You should be looking for 0.01 ppb changes. That's going to be tough with a 5 ppb offset. Bob On Sep 18, 2013, at 5:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Bob, I've been mulling over the question of a case, and I was thinking of getting a 2M brick amp and putting it inside, bolted upside down to the heat sink. Good idea? Anybody got a busted one? Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 7:22 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi The Rb's have a couple of issues: 1) Its been years since they were set on frequency and they do have a yearly drift rate 2) They have a temperature coefficient of drift that may be fairly large (0.1 ppb over -30 to +70) 3) They self heat quite a bit, so they do move temperature / need a heatsink The solution to the temperature issue is a servo controlled fan. The solution to the first drift / accuracy issue is to calibrate them against something else. Bob On Sep 18, 2013, at 7:13 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I imagine this is in the specs of the specific receiver - but I was wondering if some of you have actually measured what that is - and could report the numbers that you have found. Thanks! John Westmoreland On Wed, Sep 18, 2013 at 3:07 PM, Azelio Boriani azelio.bori...@screen.itwrote: Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you will find out that the Rb is slow... you can also check the Rb's PPS against the GPS's PPS. On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Hi There are lots of case solutions. A busted piece of HP gear is a nice way to come up with a case. Heatsink material is available from several web sites cut to order quite cheap. A simple computer fan is way more air than you will ever need. The obvious missing link is the controller. I'd run something up with a micro talking to a 4 wire fan header. That way you have tach feedback on the fan and all the PWM stuff is driven on the fan end. More or less a weekend project on a piece of pert board. Maybe a bit more than that if you do a pc board. (yes I realize this heading horribly close to talking about building things …. alarm bells are ringing somewhere…..) Bob On Sep 18, 2013, at 8:32 PM, Bob Stewart b...@evoria.net wrote: Bob, I've been mulling over the question of a case, and I was thinking of getting a 2M brick amp and putting it inside, bolted upside down to the heat sink. Good idea? Anybody got a busted one? Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 7:22 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi The Rb's have a couple of issues: 1) Its been years since they were set on frequency and they do have a yearly drift rate 2) They have a temperature coefficient of drift that may be fairly large (0.1 ppb over -30 to +70) 3) They self heat quite a bit, so they do move temperature / need a heatsink The solution to the temperature issue is a servo controlled fan. The solution to the first drift / accuracy issue is to calibrate them against something else. Bob On Sep 18, 2013, at 7:13 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I imagine this is in the specs of the specific receiver - but I was wondering if some of you have actually measured what that is - and could report the numbers that you have found. Thanks! John Westmoreland On Wed, Sep 18, 2013 at 3:07 PM, Azelio Boriani azelio.bori...@screen.itwrote: Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you will find out that the Rb is slow... you can also check the Rb's PPS against the GPS's PPS. On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] HP 5350A Frequency Counter EPROMs
HI, Sorry to come in with a Out-of-Topic question, but I am stuck. I am trying to bring an HP 5350A frequency counter back to life. I am looking for the two EPROM loads. If you can help, please contact me direct. Thanks, Bert, VE2ZAZ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO vs Rb standard
Hi Some numbers: Your Rb should hold 10 ppt per month. It's 1 second ADEV should be about 10 ppt as well. (makes it interesting to measure). Your Rb should hold 1 ppt per degree C on average. It will have a nasty glitch (around 1 ppt as it steps over a temperature boundary). Best to keep it stable to 0.5 C. For long(er) averaging times the Rb should have an ADEV that goes as the square root of tau. It'll be 10X better at 100 seconds than at 1 second. It *could* be 100X better at 10,000 seconds except for that glitch. It's not going to get beyond 0.2 ppt ADEV without some major help. All that said, with simple temperature stabilization, it should let you check out your GPSDO for drift. Within the ADEV imposed limits it'll tell you if things are holding together on a day to day / week to week basis. Bob On Sep 18, 2013, at 8:32 PM, Bob Stewart b...@evoria.net wrote: Bob, I've been mulling over the question of a case, and I was thinking of getting a 2M brick amp and putting it inside, bolted upside down to the heat sink. Good idea? Anybody got a busted one? Bob From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Wednesday, September 18, 2013 7:22 PM Subject: Re: [time-nuts] GPSDO vs Rb standard Hi The Rb's have a couple of issues: 1) Its been years since they were set on frequency and they do have a yearly drift rate 2) They have a temperature coefficient of drift that may be fairly large (0.1 ppb over -30 to +70) 3) They self heat quite a bit, so they do move temperature / need a heatsink The solution to the temperature issue is a servo controlled fan. The solution to the first drift / accuracy issue is to calibrate them against something else. Bob On Sep 18, 2013, at 7:13 PM, John C. Westmoreland, P.E. j...@westmorelandengineering.com wrote: Azelio and Fellow Time Nuts, Isn't the GPS 1PPS signal supposed to be 'precise' to within what error? I imagine this is in the specs of the specific receiver - but I was wondering if some of you have actually measured what that is - and could report the numbers that you have found. Thanks! John Westmoreland On Wed, Sep 18, 2013 at 3:07 PM, Azelio Boriani azelio.bori...@screen.itwrote: Instead of using the Rb's PPS, use the GPS receiver's PPS. Maybe you will find out that the Rb is slow... you can also check the Rb's PPS against the GPS's PPS. On Wed, Sep 18, 2013 at 11:47 PM, Bob Stewart b...@evoria.net wrote: I hooked the Rb's 1PPS to the trigger input on my old Tek 455, 10MHz GPSDO to Channel A, .05us trace, and turned the lights out so I could see it. The 10MHz is marching right to left about 1 cycle every 20 seconds. So, can I say that the Rb considers my GPSDO to be too fast by about 5ppb? Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] GPS with 10KHz output
Hi, Does anyone know the suitability of this module for GPSDO ? I am new to the group. Thanks, Bill R http://www.ebay.com/itm/Navman-jupiter-T-Tu60-GPS-Kit-1pps-10khz-GPS-Module-/260790984470?pt=US_Ham_Radio_Amplifiershash=item3cb85a9f16 ___ time-nuts mailing 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] New NTBW50AA
Dave wrote: You didn't say, but I get the feeling maybe I should be getting smaller ppt numbers? When you say noisy, is high ppt generally a result of excess noise (front end NF)? Hard to say about the ppt numbers -- my TBolts give somewhat lower numbers than you are getting, but they use different OCXOs with different phaselocking circuitry, so I can't say what would be considered normal for the model you have. Also, as several have said already, the GPSDO is measuring itself with itself (no independent reference), so its proclamations need to be taken with more than some caution. Excess noise on the GPS signals (from whatever cause) causes timing errors in the GPS, which makes the GPS think the oscillator needs correction, which leads to DAC adjustments that aren't necessary. But if you are seeing at least some numbers in the 50 dBc and higer range, there is nothing further you can do in this regard. (Well, if the model you have supports it, you can set a signal level mask that will exclude satellites with signals below a dBc threshold of your choice. As with the elevation mask, if you get too aggressive you may force the unit into holdover when there are a few OK but not great signals.) As we all have said repeatedly, you need a good, accurate survey. Also, it is the nature of crystal oscillators that when they are disturbed (turned off and back on, frequency adjusted, handling/moving, fast temperature changes, etc., etc.) that they take time to settle back down -- often months. Now that you have a permanent antenna location, do a precision survey, SAVE IT, then let the unit sit undisturbed for several months and see where you are. You are certainly in the ballpark -- there are clearly no gross problems. Bob presumably knows more than I do about non-TBolt Trimbles (since I know nothing about them). If he says you can't adjust the TC and gain I'd be inclined to believe him. (And if you can't adjust the gain, there is no point in measuring the EFC characteristics of the OCXO, except for curiosity.) The antenna is a Lucent PCTEL GPS-TMG-HR-26N, High Rejection 26dB With Enhanced Narrow Band Filtering, apparently for high RF environments, only one I've got or tried You may have read on another thread about narrow bandpass filters tending to have rising group delay at the passband edges. An antenna with Enhanced Narrow Band Filtering very likely has more group delay error than one with more gentle filtering, so it is possible that satellites with high doppler shifts are causing the GPS timing solution to shift around more than it would with a different antenna. The one you have is presumably good enough for cell timing, since that is what it was designed for. The question is whether the lower group delay of an antenna without Enhanced Narrow Band Filtering would be enough better that you could tell. Without measuring the filters, we can't really predict what to expect. You might ask the seller if he would exchange your antenna for one that doesn't have the extra filtering. You almost certainly don't need it in your rural location, and an antenna without it would at least not be any worse, all else equal. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS with 10KHz output
If you ned the 10KHz, Jupiter is one that has been used. I think a 10KHz GPS will make your GPSDO converge quickly but for long term use a 1Hz GPS works as well and will be easier t replace years from now. Also a 1HZ GPS with about equivalent performance is MUCH less expensive (see ebay 271152854221 which is $15)But 10KHz does allow a simpler design for the GPSDO that can be done 100% analog On Wed, Sep 18, 2013 at 7:21 PM, Bill Reed br...@otelco.net wrote: Hi, Does anyone know the suitability of this module for GPSDO ? I am new to the group. Thanks, Bill R http://www.ebay.com/itm/Navman-jupiter-T-Tu60-GPS-Kit-1pps-10khz-GPS-Module-/260790984470?pt=US_Ham_Radio_Amplifiershash=item3cb85a9f16 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
