Re: [time-nuts] HP Z3805A com port and monitoring questions
Tom, It looks like they have a pForth interpreter running in there under PSOS: http://code.google.com/p/pforth/. Is there a mechanism to switch from SCPI to the Forth interpreter? david Trimble and HP took different approaches on their GPSDO's. Trimble lets you get into things and fiddle around. HP is much more a black box. I have never seen anything that lets you fiddle' with one of the HP units. Hi Bob, I'm glad you asked. True, the Trimble TSIP binary command set lets you fiddle and the HP SCPI command set is much easier to use but more limited by comparison. But there's also a rich under-the-hood layer on the HP units. Spend some time with this file and you'll see what I mean: http://leapsecond.com/museum/z3801a/z3801a-bin.txt I explored the functionality in some detail during my hp GPSDO DAC dither investigation some years ago. Contact me offline. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ? (Dale J. Robertson)
Dale - To your question re BPSK and DPSK. In both modes the phase shift is 180 degrees. Straight PSK has the issue of determining the 1's from the 0's, at the receiver as there is no phase reference. To avoid this DPSK encodes the the serial data stream prior to the bi-phase modulator. As I recall (at 1 AM) the method is like this. If the present bit to be sent is a 1 the phase of the carrier is inverted. If it is a zero the phase is not inverted. This is easily sorted out in the receiver using a flip flop and an XOR. However recovery of the carrier must occur before decoding of the data stream and is done the same way for both - at least in classical receivers. Squaring Loop or Costas Loop. -john k6iql ___ time-nuts mailing 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] documentation for beginners (was: Followup (still want a GPS-type NTP refclock))
And don't forget those NTP people. BTW, is there an NTP packet exchange example? That is, what is the typical conversation between an NTP server and a client? On Mon, Oct 22, 2012 at 7:28 AM, Hal Murray hmur...@megapathdsl.net wrote: t...@leapsecond.com said: BTW, the best time frequency glossary on the web so far is at: http://tf.nist.gov/general/glossary.htm There's also an index at: http://tf.nist.gov/general/enc-index.htm That's a good example of a point I didn't make last time... Official sites like NIST usually don't do a good job of linking out to other sites. When they do, they often go to official or manufacturers sites rather than informal/amateur sites. That's not bad, but it might not help newbies find places like time-nuts when they are trying to get started. I should have mentioned that there is nothing wrong with having multiple FAQ/Wiki sites run by amateurs. The trick is that they usually cross-link to each other. If google (or dumb luck) takes you to one, that usually helps you find the others. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] documentation for beginners
I already have a number of time-nuts related wiki pages on my site, anybody is welcome to start a new one. It is open to anyone. Didier KO4BB www.ko4bb.com Sent from my Droid Razr 4G LTE wireless tracker. -Original Message- From: David J Taylor david-tay...@blueyonder.co.uk To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sun, 21 Oct 2012 12:11 PM Subject: Re: [time-nuts] documentation for beginners I started a small Wiki for the Plane Plotter program, using the free pbworks site: http://planeplotter.pbworks.com The site is easy to use, and you can have multiple authors and as many readers as you like. I could start a Wiki for Time Nuts, if you like, or anyone else could start one of course. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Adjusting HP 5065A frequency
Tom I have two questions what should the range, resolution and stability of the delay generator be and how much do you think a digital loop driven by a Tbolt would degrade short and medium precision. What is your definition of short and medium? Bert Kehren In a message dated 10/22/2012 12:25:08 A.M. Eastern Daylight Time, t...@leapsecond.com writes: Three companies come to mind for phase microsteppers. A popular one decades ago was made by Austron (model 2055A). I got mine on eBay but they are not as common now as ten years ago. The current models by Symmetricom and Spectra Dynamics are extremely high-end (expensive) and overqualified for use with a vintage rubidium oscillator. If you visit NIST or USNO you will see these impressive units. It would be a very fun project to make your own. I suspect other group members could either help you or would eagerly employ your design for their own use. But -- before you decide on a hardware solution see if you can do it in software. An analogy is what we do with GPS 1PPS sawtooth errors. There are two ways to deal with this. One is to capture the correction message over RS232, measure the DUT vs. GPS 1PPS with a TIC, and then numerically apply the sawtooth correction with one line of code. Several of the popular GPS monitor programs do this automatically for you (TBoltmon and TAC32, for example). The software solution is perfect to the granularity of the sawtooth message, typically 1 ns. The hardware implementation usually involves a PIC and a programmable delay generator. The PIC listens for the correction message over RS232 and then has plenty of time (up to one second) to program the delay chip. When the hardware 1PPS arrives it is delayed to compensate for the aforementioned sawtooth error. The result is a hardware 1PPS that's quite close to the ideal 1PPS, limited again by the granularity of the message, as well as offset or linearity errors in the delay chip. So that's the analogy. To apply this to your rubidium, ask yourself which instruments or measurements or users are downstream of your 5065A 10 MHz output. Can they deal with daily software corrections to a stable but slightly imprecise frequency, or do they really need the frequency to be as accurate as possible at all times. There's a third alternative as well. You might consider using your 5065A as the LO in a GPSDO. This will sacrifice some short- and mid-term precision due to additive noise, but it will guarantee the best possible long-term accuracy. /tvb - Original Message - From: Edgardo Molina To: Tom Van Baak ; Discussion of precise time and frequency measurement Sent: Sunday, October 21, 2012 8:49 PM Subject: Re: [time-nuts] Adjusting HP 5065A frequency Dear Tom, Good evening. In relation to your last comments on this and other subjects, I am sharing some thoughts and experience about it. I took the liberty to separate the topics as to ease the interested parties to follow up accordingly. TNX. a. Information you kindly provided and the index for newbies: Thank you! You just provided me with lots of new ideas and information on the subject. You have very valuable information in your web site. As Hal was saying, an index should be done anywhere so it could be easier for the rest of us to locate the information. I am planning soon to build a web page for my lab. In english of course for everybody to share my experiences. I could work on an index to point out to the various sources of information and topics that are difficult to find. That I think could expedite things a little bit. b. Phase Micro steppers: I saw the phase micro steppers working at CENAM time scale. I was wondering that the technique could be translated to my 5065As and not trying to touch them so often. If I am assuming correctly and the technique could be used with the HP Rb standards. Are those phase micro steppers easy to find? I mean, affordable in the second market? If there is one of course. I saw the ones used at CENAM are produced by SpectraDynamics in Colorado. According to Mike Lombardi it is a small highly specialized company with a small market to serve. I could translate it as expensive and exotic : ) Am I correct? c. Thunderbolt and my will to share initial experiences: I am gathering a lot of information on the Thunderbolts as I am using them in my thesis work. I bought a couple of them. If my information or novice experience with these receivers is good for anybody, I would be more than glad to share it. Thank you. Kind regards, Edgardo Molina Dirección IPTEL www.iptel.net.mx T : 55 55 55202444 M : 04455 20501854 Piensa en Bits SA de CV Información anexa: CONFIDENCIALIDAD DE INFORMACION Este mensaje tiene carácter confidencial. Si usted no es el destinarario de este mensaje, le suplicamos se lo notifique al remitente
Re: [time-nuts] GPSDO three cornered comparisons
I very much agree with this. It works because OCXO thermal effects you're looking at are in a domain where GPS is able to provide an adequate reference against which to measure. Where this scheme doesn't work is with short-term OCXO noise or thermal transients (GPS isn't a stable enough reference at short tau), or long-term GPS accuracy (OCXO isn't a stable enough reference at long tau). That's the beauty of a GPSDO - you essentially get the best of both worlds. Lucky for you, the temperature effects you speak of (especially diurnal) occur a little past the cross-over point. Otherwise I'm not sure you'd be able to measure it your way. Another way of saying it -- you can use the OCXO to measure short-term tempco of the GPS receiver, or you can use GPS to measure long-term tempco in the OCXO. But if the tempco is anywhere near the cross-over point you can't be sure if it's OCXO or GPS. To solve that you do it the old-fashioned way: with a thermometer and a 5065A/cesium/maser reference. /tvb - Original Message - From: Said Jackson saidj...@aol.com To: Tom Van Baak t...@leapsecond.com; Discussion of precise time and frequency measurement time-nuts@febo.com Cc: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, October 21, 2012 9:27 PM Subject: Re: [time-nuts] GPSDO three cornered comparisons Tom, This is true for the phase data and calculating short term stability, but not necessarily for measuring the tempco of the OCXO.. If we assume most GPSDOs have very stable DACs and DAC references (I have measured typical DAC units to be at least 10x more stable than the best DOCXOs over temperature) then the changes in DAC voltage over time can give an extremely accurate absolute measurement of the OCXOs thermal performance. The loop will cause random chaotic small corrections to be made as it tracks the GPS phase. All we have to do is filter these small AC type corrections out of the reported EFC voltage with a reasonable time constant, say 30 minutes, then we are left with a very good representation of how the OCXO reacts to ambient changes. Knowing the sensitivity of the EFC input allows calculation of the changes in frequency that the OCXO is generating over temperature and time. The CSAC GPSDO makes this even easier as it is steered digitally in parts per trillion and gives the steering info in ppt as well, and also has two very accurate high resolution temp sensors on board. Most of the time the resulting curve will have a very strong diurnal correlation to ambient temperature. Knowing the ambient temperature changes around the OCXO then allows us to easily calculate the thermal stability of the OCXO (again assuming the Dac voltage tempco is 10x or more smaller then the OCXO thermal stability). For example, assume the diurnal voltage changes are +/-60 microvolt (typical DOCXO) and we know the EFC sensitivity is 8Hz/V and the temperature changes +/-5 Degrees C then: 8Hz/V * 0.00012V / 10C = about 1E-011 per Degree C So that OCXO would have a thermal stability of 0.6ppb peak to peak over a typical temp range of 0C to 60C which is quite good. All that is needed to make this measurement is a frequency counter to establish the EFC sensitivity of the OCXO once.. And that counter is doing a relative measurement, so its inaccurate internal reference can be used.. Bye, Said On Oct 21, 2012, at 17:39, Tom Van Baak t...@leapsecond.com wrote: David, This is problematic, since the Z38xx software is not really measuring the output of the GPSDO. Instead it's taking the internally reported PLL time error measurements from the disciplining loop and pretending they are a measure of real performance as measured against a real frequency standard. However, this PLL data can be used to see how well the loop is working; that in itself can be interesting. For example, differences in an ADEV plot of the PLL error term can be used to reveal the time constant used by the PLL. So one can still use the ADEV-style calculation on the phase error of a closed PLL; but don't confuse this with the actual performance of the GPSDO as a time/frequency standard. Does this make sense, or shall I explain more? Or, if you have some raw data you can send me off-line I'll take a look at it. Thanks, /tvb - Original Message - From: David Hooke dho...@gmail.com To: time-nuts@febo.com Sent: Sunday, October 21, 2012 4:44 PM Subject: Re: [time-nuts] GPSDO three cornered comparisons Tom, The ADEVs I quoted are from the Z83xx software, so I assume it's comparing time from the GPS system to it's own oscillator's output, in the same way that LH does. I've been monitoring the basic stuff you suggested. It's because I don't have a known reference to compare the units with that I want to use the 3-corner method to start sorting the wheat from the chaff. david I have an HP 58503A and a Symmetricom
Re: [time-nuts] Adjusting HP 5065A frequency
Hi Bert, Not sure about the range/resolution. That would depend on how the standard is used and what its frequency drift rate is. The stability doesn't have to be too much better than the standard itself. The Austron 2055 resolution is 1e-14, IIRC. The Symmetricom AOG is 1e-19 (overkill). What I've found in some GPSDO and passive atomic standards (e.g., Rb or Cs) is that as soon as you turn on the DAC and enable the loop, you get more short-term noise, say in the range of 1 to 100 seconds. That's why for best stability you always switch off the loop during a sensitive measurement. Many older Cs had a Cs off switch for this. Not only did it conserve cesium but it also means you're running straight off the high-quality OCXO. This is also true for GPSDO, like the TBolt which allows you to turn off disciplining with a s/w command. In general, when you discipline a OCXO you get that characteristic ADEV hump. This is expected, a natural byproduct of combining two unknowns, one that's assumed to be better at short tau and worse at long tau (e.g., OCXO) and one that's assumed to be better at long tau and worse at short tau (e.g., Rb cell, or Cs beam, or GPS receiver). At some point there is a cross-over and you know/assume that at that point each must be contributing 1/sqrt(2) of the noise. To see the humps in living color, refer to: http://www.leapsecond.com/pages/gpsdo/ To answer your question about short/medium/long, I guess in this case short is tau left of the hump; medium is the hump, and long is tau to the right of the hump. /tvb - Original Message - From: ewkeh...@aol.com To: time-nuts@febo.com Sent: Monday, October 22, 2012 4:04 AM Subject: Re: [time-nuts] Adjusting HP 5065A frequency Tom I have two questions what should the range, resolution and stability of the delay generator be and how much do you think a digital loop driven by a Tbolt would degrade short and medium precision. What is your definition of short and medium? Bert Kehren In a message dated 10/22/2012 12:25:08 A.M. Eastern Daylight Time, t...@leapsecond.com writes: Three companies come to mind for phase microsteppers. A popular one decades ago was made by Austron (model 2055A). I got mine on eBay but they are not as common now as ten years ago. The current models by Symmetricom and Spectra Dynamics are extremely high-end (expensive) and overqualified for use with a vintage rubidium oscillator. If you visit NIST or USNO you will see these impressive units. It would be a very fun project to make your own. I suspect other group members could either help you or would eagerly employ your design for their own use. But -- before you decide on a hardware solution see if you can do it in software. An analogy is what we do with GPS 1PPS sawtooth errors. There are two ways to deal with this. One is to capture the correction message over RS232, measure the DUT vs. GPS 1PPS with a TIC, and then numerically apply the sawtooth correction with one line of code. Several of the popular GPS monitor programs do this automatically for you (TBoltmon and TAC32, for example). The software solution is perfect to the granularity of the sawtooth message, typically 1 ns. The hardware implementation usually involves a PIC and a programmable delay generator. The PIC listens for the correction message over RS232 and then has plenty of time (up to one second) to program the delay chip. When the hardware 1PPS arrives it is delayed to compensate for the aforementioned sawtooth error. The result is a hardware 1PPS that's quite close to the ideal 1PPS, limited again by the granularity of the message, as well as offset or linearity errors in the delay chip. So that's the analogy. To apply this to your rubidium, ask yourself which instruments or measurements or users are downstream of your 5065A 10 MHz output. Can they deal with daily software corrections to a stable but slightly imprecise frequency, or do they really need the frequency to be as accurate as possible at all times. There's a third alternative as well. You might consider using your 5065A as the LO in a GPSDO. This will sacrifice some short- and mid-term precision due to additive noise, but it will guarantee the best possible long-term accuracy. /tvb - Original Message - From: Edgardo Molina To: Tom Van Baak ; Discussion of precise time and frequency measurement Sent: Sunday, October 21, 2012 8:49 PM Subject: Re: [time-nuts] Adjusting HP 5065A frequency Dear Tom, Good evening. In relation to your last comments on this and other subjects, I am sharing some thoughts and experience about it. I took the liberty to separate the topics as to ease the interested parties to follow up accordingly. TNX. a. Information you kindly provided and the index for newbies: Thank you! You just provided me with lots of new ideas and information on the subject. You have very valuable
Re: [time-nuts] Adjusting HP 5065A frequency
The hump is the DAC update frequency measure: fast update - hump towards the left, slow update - towards the right. Better update fast or slow: recently it was pointed out that fast should be better and this will shift the hump in the 1 to 10 seconds range. On Mon, Oct 22, 2012 at 1:32 PM, Tom Van Baak t...@leapsecond.com wrote: Hi Bert, Not sure about the range/resolution. That would depend on how the standard is used and what its frequency drift rate is. The stability doesn't have to be too much better than the standard itself. The Austron 2055 resolution is 1e-14, IIRC. The Symmetricom AOG is 1e-19 (overkill). What I've found in some GPSDO and passive atomic standards (e.g., Rb or Cs) is that as soon as you turn on the DAC and enable the loop, you get more short-term noise, say in the range of 1 to 100 seconds. That's why for best stability you always switch off the loop during a sensitive measurement. Many older Cs had a Cs off switch for this. Not only did it conserve cesium but it also means you're running straight off the high-quality OCXO. This is also true for GPSDO, like the TBolt which allows you to turn off disciplining with a s/w command. In general, when you discipline a OCXO you get that characteristic ADEV hump. This is expected, a natural byproduct of combining two unknowns, one that's assumed to be better at short tau and worse at long tau (e.g., OCXO) and one that's assumed to be better at long tau and worse at short tau (e.g., Rb cell, or Cs beam, or GPS receiver). At some point there is a cross-over and you know/assume that at that point each must be contributing 1/sqrt(2) of the noise. To see the humps in living color, refer to: http://www.leapsecond.com/pages/gpsdo/ To answer your question about short/medium/long, I guess in this case short is tau left of the hump; medium is the hump, and long is tau to the right of the hump. /tvb - Original Message - From: ewkeh...@aol.com To: time-nuts@febo.com Sent: Monday, October 22, 2012 4:04 AM Subject: Re: [time-nuts] Adjusting HP 5065A frequency Tom I have two questions what should the range, resolution and stability of the delay generator be and how much do you think a digital loop driven by a Tbolt would degrade short and medium precision. What is your definition of short and medium? Bert Kehren In a message dated 10/22/2012 12:25:08 A.M. Eastern Daylight Time, t...@leapsecond.com writes: Three companies come to mind for phase microsteppers. A popular one decades ago was made by Austron (model 2055A). I got mine on eBay but they are not as common now as ten years ago. The current models by Symmetricom and Spectra Dynamics are extremely high-end (expensive) and overqualified for use with a vintage rubidium oscillator. If you visit NIST or USNO you will see these impressive units. It would be a very fun project to make your own. I suspect other group members could either help you or would eagerly employ your design for their own use. But -- before you decide on a hardware solution see if you can do it in software. An analogy is what we do with GPS 1PPS sawtooth errors. There are two ways to deal with this. One is to capture the correction message over RS232, measure the DUT vs. GPS 1PPS with a TIC, and then numerically apply the sawtooth correction with one line of code. Several of the popular GPS monitor programs do this automatically for you (TBoltmon and TAC32, for example). The software solution is perfect to the granularity of the sawtooth message, typically 1 ns. The hardware implementation usually involves a PIC and a programmable delay generator. The PIC listens for the correction message over RS232 and then has plenty of time (up to one second) to program the delay chip. When the hardware 1PPS arrives it is delayed to compensate for the aforementioned sawtooth error. The result is a hardware 1PPS that's quite close to the ideal 1PPS, limited again by the granularity of the message, as well as offset or linearity errors in the delay chip. So that's the analogy. To apply this to your rubidium, ask yourself which instruments or measurements or users are downstream of your 5065A 10 MHz output. Can they deal with daily software corrections to a stable but slightly imprecise frequency, or do they really need the frequency to be as accurate as possible at all times. There's a third alternative as well. You might consider using your 5065A as the LO in a GPSDO. This will sacrifice some short- and mid-term precision due to additive noise, but it will guarantee the best possible long-term accuracy. /tvb - Original Message - From: Edgardo Molina To: Tom Van Baak ; Discussion of precise time and frequency measurement Sent: Sunday, October 21, 2012 8:49 PM Subject: Re: [time-nuts] Adjusting HP 5065A frequency Dear Tom, Good evening. In relation to your last comments on this and
Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ?
Paul, I would also be interested in how you built your simulator. I'm considering building a simple one myself. I'll probably have mine just toggle the phase every 100 ms initially. Dale -Original Message- From: paul swed Sent: Sunday, October 21, 2012 11:08 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ? Jameco had them on sale for 20 cents each so I purchased some. Moved the clock up frequency for 60 Khz and injected the 60Khz BPSK. (I built a simulator) It did not track and in general produced noise. I understand you can use 2 frequencies to drive it and I tried both from synth gens. I was looking at the RDS decoders and the data seemed to be differential. Set it aside at that point. I am curious as to why it did not work. Like everyone here would be great if it worked Regards Paul WB8TSL On Sun, Oct 21, 2012 at 10:55 PM, Dale J. Robertson d...@nap-us.com wrote: Paul, I'm trying to understand your reference to 'differential BPSK' all the RDS references I've looked at indicate a 180 degree phase shift just like WWVB. I'm thinking that differential and antipodal are just different words for the same thing Regards, Dale Sent from my iPhone On Oct 21, 2012, at 10:03 PM, paul swed paulsw...@gmail.com wrote: Because it use differential BPSK. I have a number of them and was trying it. There is a test pin that might make it useful. Regards Paul WB8TSL On Sun, Oct 21, 2012 at 9:14 PM, Dale J. Robertson d...@nap-us.com wrote: While looking for other stuff I came across the data sheet for the NXP Semi SAA6579. The chip is a purpose built demodulator for RDS (which utilises a 57 KHz ABPSK subcarrier on FM broadcast that is) used for traffic, song info etc. This chip has an anti-aliasing front end low pass filter and an 8th order bandpass filter followed by a costas loop and provides a phase synchronous regenerated carrier. What's interesting is that the switched cap bandpass filter and the synchronous detector are both driven by clocks derived from a local crystal oscillator which is spec'd at 4.332 or 8.664 MHz (76 or 152 X carrier chosen by a mode select pin) I'm thinking it should be possible to use a 4.56 or 9.12 MHz crystal or external clock to use this chip as-is on 60 KHz. Have a look at the data sheet and tell me why I'm full of it. Jameco is closing out these chips in DIP-16 at a nickel apiece, $3.00/hundred. Dale NV8U __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nuts 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] Adjusting HP 5065A frequency
Tom A good place to start is with a manual of the Austron 2055 delay if there is real interest. Does any one have it in PDF form? As to the disciplining a Rb or specifically a HP5065A, the filter part is the challenge. Having worked on it for the last ten years always using Brooks loop and developing work around's it will do every thing except temperature control and barometric pressure. I have done temperature analog but rely mainly on holding the Rb temperature stable within a tenth degree C. Bob recently put things in perspective when there was talk about a 32 bit DAC. On one side you have GPS and time averaging is required to get full use of it. That is why a Rb is uniquely qualified for it. The original Shera input implemented on a 1 $ G/A is more than enough for time capture wether using a sawtooth corrected GPS receiver or a Tbolt. On the other end a LTC1655 is again more than enough in an Rb application. You can use it 16 bit direct or dither two or 4 bits. Filter is easy and do not forget that the Rb has an additional filter between cell and OCXO. Brooks V402NE will do the job, how ever others and I have not been able to buy some in the last nine month. Any one knows what is going on? What is needed is some one in the group be willing and able to step up to the plate and develop the filter on a PIC with all the things learned, and believe me, we are still learning as we adapt a M100/8600 via a Tbolt . I will be willing to help with every thing except the PIC. If you bring out the C field coil directly you have full isolation and do not have to worry about ground loops. A complete unit would cost less than $ 40 and more important be assembled by any one. I brought it up before but no one responded. If no response I will still be able to do every thing with the HP5065A RVFR that was given to me. Bert Kehren In a message dated 10/22/2012 7:33:08 A.M. Eastern Daylight Time, t...@leapsecond.com writes: Hi Bert, Not sure about the range/resolution. That would depend on how the standard is used and what its frequency drift rate is. The stability doesn't have to be too much better than the standard itself. The Austron 2055 resolution is 1e-14, IIRC. The Symmetricom AOG is 1e-19 (overkill). What I've found in some GPSDO and passive atomic standards (e.g., Rb or Cs) is that as soon as you turn on the DAC and enable the loop, you get more short-term noise, say in the range of 1 to 100 seconds. That's why for best stability you always switch off the loop during a sensitive measurement. Many older Cs had a Cs off switch for this. Not only did it conserve cesium but it also means you're running straight off the high-quality OCXO. This is also true for GPSDO, like the TBolt which allows you to turn off disciplining with a s/w command. In general, when you discipline a OCXO you get that characteristic ADEV hump. This is expected, a natural byproduct of combining two unknowns, one that's assumed to be better at short tau and worse at long tau (e.g., OCXO) and one that's assumed to be better at long tau and worse at short tau (e.g., Rb cell, or Cs beam, or GPS receiver). At some point there is a cross-over and you know/assume that at that point each must be contributing 1/sqrt(2) of the noise. To see the humps in living color, refer to: http://www.leapsecond.com/pages/gpsdo/ To answer your question about short/medium/long, I guess in this case short is tau left of the hump; medium is the hump, and long is tau to the right of the hump. /tvb - Original Message - From: ewkeh...@aol.com To: time-nuts@febo.com Sent: Monday, October 22, 2012 4:04 AM Subject: Re: [time-nuts] Adjusting HP 5065A frequency Tom I have two questions what should the range, resolution and stability of the delay generator be and how much do you think a digital loop driven by a Tbolt would degrade short and medium precision. What is your definition of short and medium? Bert Kehren In a message dated 10/22/2012 12:25:08 A.M. Eastern Daylight Time, t...@leapsecond.com writes: Three companies come to mind for phase microsteppers. A popular one decades ago was made by Austron (model 2055A). I got mine on eBay but they are not as common now as ten years ago. The current models by Symmetricom and Spectra Dynamics are extremely high-end (expensive) and overqualified for use with a vintage rubidium oscillator. If you visit NIST or USNO you will see these impressive units. It would be a very fun project to make your own. I suspect other group members could either help you or would eagerly employ your design for their own use. But -- before you decide on a hardware solution see if you can do it in software. An analogy is what we do with GPS 1PPS sawtooth errors. There are two ways to deal with this. One is to capture the correction message over RS232, measure the DUT vs. GPS 1PPS with
Re: [time-nuts] documentation for beginners (was: Followup (still want a GPS-type NTP refclock))
Dear Azelio, Count on me for that. I am doing my thesis in network synchronization and NTP will be the main course. I will be posting a brief of the thesis and all related information in my soon to be published web page. I dream NTP now… Regards, Edgardo Molina Dirección IPTEL www.iptel.net.mx T : 55 55 55202444 M : 04455 20501854 Piensa en Bits SA de CV Información anexa: CONFIDENCIALIDAD DE INFORMACION Este mensaje tiene carácter confidencial. Si usted no es el destinarario de este mensaje, le suplicamos se lo notifique al remitente mediante un correo electrónico y que borre el presente mensaje y sus anexos de su computadora sin retener una copia de los mismos. Queda estrictamente prohibido copiar este mensaje o hacer usode el para cualquier propósito o divulgar su en forma parcial o total su contenido. Gracias. NON-DISCLOSURE OF INFORMATION This email is strictly confidential and may also be privileged. If you are not the intended recipient please immediately advise the sender by replying to this e-mail and then deleting the message and its attachments from your computer without keeping a copy. It is strictly forbidden to copy it or use it for any purpose or disclose its contents to any third party. Thank you. On Oct 22, 2012, at 3:14 AM, Azelio Boriani azelio.bori...@screen.it wrote: And don't forget those NTP people. BTW, is there an NTP packet exchange example? That is, what is the typical conversation between an NTP server and a client? On Mon, Oct 22, 2012 at 7:28 AM, Hal Murray hmur...@megapathdsl.net wrote: t...@leapsecond.com said: BTW, the best time frequency glossary on the web so far is at: http://tf.nist.gov/general/glossary.htm There's also an index at: http://tf.nist.gov/general/enc-index.htm That's a good example of a point I didn't make last time... Official sites like NIST usually don't do a good job of linking out to other sites. When they do, they often go to official or manufacturers sites rather than informal/amateur sites. That's not bad, but it might not help newbies find places like time-nuts when they are trying to get started. I should have mentioned that there is nothing wrong with having multiple FAQ/Wiki sites run by amateurs. The trick is that they usually cross-link to each other. If google (or dumb luck) takes you to one, that usually helps you find the others. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] documentation for beginners (was: Followup (still want a GPS-type NTP refclock))
azelio.bori...@screen.it said: And don't forget those NTP people. BTW, is there an NTP packet exchange example? That is, what is the typical conversation between an NTP server and a client? What are you looking for? The wikipedia page is a good introduction: http://en.wikipedia.org/wiki/Network_Time_Protocol NTP is a big sub-set of time-nut activity with an active community of geeks. I think any time-nut documentation should point to other info rather than duplicate their activity. http://www.ntp.org/ There is also PTP, IEEE 1588 The basic NTP conversation is the typical client/server exchange of a pair of UDP packets. tcpdump will decode the contents so you can easily use it to get a quick introduction. (That's assuming you have a system running NTP that already generates the packets.) -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Adjusting HP 5065A frequency
(( replied at beginning to be consistent with this thread )) Thanks, this has done a good job at furthering my understanding about error (one way of describing adev as I understand) vs short and long tau times. I don't have anything to add on that subject, but but I have a question about a page you linked... http://www.leapsecond.com/pages/gpsdo/ section: Trimble Thunderbolt GPSDO (OCXO version) The text This version of the Thunderbolt has an OCXO (unlike the model shown on the Trimble web page). These are also recently available on the surplus market. just before chart image titled Free vs. Locked: GPSDO [#a20] So when I did a quick fact check, I was immediately confused: (re-quote) ...version of the Thunderbolt has an OCXO (unlike the model shown on the Trimble web page)... Fact checking with today's site: http://www.trimble.com/timing/ The TBoltI can even find is the Thunderbolt® E GPS Disciplined Clock Which in turn, if I follow the link: Under Key features section: Ovenized quartz oscillator provides stable 10 MHz and 1 PPS output to maximizes bandwidth Leaves me wondering. Does trimble even offer a non-ovenized TBolt at this point? I can logically infer / assume that at one point, they did, but I don't know what to think now. New and curious, Sarah On 10/22/2012 7:32 AM, Tom Van Baak wrote: Hi Bert, Not sure about the range/resolution. That would depend on how the standard is used and what its frequency drift rate is. The stability doesn't have to be too much better than the standard itself. The Austron 2055 resolution is 1e-14, IIRC. The Symmetricom AOG is 1e-19 (overkill). What I've found in some GPSDO and passive atomic standards (e.g., Rb or Cs) is that as soon as you turn on the DAC and enable the loop, you get more short-term noise, say in the range of 1 to 100 seconds. That's why for best stability you always switch off the loop during a sensitive measurement. Many older Cs had a Cs off switch for this. Not only did it conserve cesium but it also means you're running straight off the high-quality OCXO. This is also true for GPSDO, like the TBolt which allows you to turn off disciplining with a s/w command. In general, when you discipline a OCXO you get that characteristic ADEV hump. This is expected, a natural byproduct of combining two unknowns, one that's assumed to be better at short tau and worse at long tau (e.g., OCXO) and one that's assumed to be better at long tau and worse at short tau (e.g., Rb cell, or Cs beam, or GPS receiver). At some point there is a cross-over and you know/assume that at that point each must be contributing 1/sqrt(2) of the noise. To see the humps in living color, refer to: http://www.leapsecond.com/pages/gpsdo/ To answer your question about short/medium/long, I guess in this case short is tau left of the hump; medium is the hump, and long is tau to the right of the hump. /tvb - Original Message - From: ewkeh...@aol.com To: time-nuts@febo.com Sent: Monday, October 22, 2012 4:04 AM Subject: Re: [time-nuts] Adjusting HP 5065A frequency Tom I have two questions what should the range, resolution and stability of the delay generator be and how much do you think a digital loop driven by a Tbolt would degrade short and medium precision. What is your definition of short and medium? Bert Kehren In a message dated 10/22/2012 12:25:08 A.M. Eastern Daylight Time, t...@leapsecond.com writes: Three companies come to mind for phase microsteppers. A popular one decades ago was made by Austron (model 2055A). I got mine on eBay but they are not as common now as ten years ago. The current models by Symmetricom and Spectra Dynamics are extremely high-end (expensive) and overqualified for use with a vintage rubidium oscillator. If you visit NIST or USNO you will see these impressive units. It would be a very fun project to make your own. I suspect other group members could either help you or would eagerly employ your design for their own use. But -- before you decide on a hardware solution see if you can do it in software. An analogy is what we do with GPS 1PPS sawtooth errors. There are two ways to deal with this. One is to capture the correction message over RS232, measure the DUT vs. GPS 1PPS with a TIC, and then numerically apply the sawtooth correction with one line of code. Several of the popular GPS monitor programs do this automatically for you (TBoltmon and TAC32, for example). The software solution is perfect to the granularity of the sawtooth message, typically 1 ns. The hardware implementation usually involves a PIC and a programmable delay generator. The PIC listens for the correction message over RS232 and then has plenty of time (up to one second) to program the delay chip. When the hardware 1PPS arrives it is delayed to compensate for the aforementioned sawtooth error.
Re: [time-nuts] documentation for beginners
t...@leapsecond.com said: I should also mention the choice to have John Ackermann host the list (free) along with all the TAPR mailing lists has proven itself again and again. Few entities on the web have been this solid for a decade. A couple of times a year we have trouble with S/N ratio, but those tend to be short lived. Many thanks to Tom and John. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Adjusting HP 5065A frequency
Hi One simple / dirty approach, assuming you are starting from 5 or 10 MHz: Lock up a VCXO at 100 MHz from the source via a wide band PLL. Divide it down to 1 pps by the usual techniques. Slip the counter (add / subtract one count) to get things within 10 ns. Now all you need is a +/- 5 ns adjustment. Inject a DC offset into the PLL with an DAC to steer it off of it's mid point. A cheap 16 bit DAC would get you to below 200 fs. With a wide band (say 1 KHz) loop, the ADEV of the VCXO compared to the reference should be identical at anything past 100 ms. A well filtered DAC voltage should not mess that up. Yes you need to do a little calibration. If you use something like an XOR as a phase detector, and run the DAC off the same supply as the XOR, cal should not be too hard. No, NIST will not be drooling at your gizmo any time soon. You will have your PPS steered far closer to UTC than any of us is likely to be able to measure. Cost wise there's not a lot there. The main thing to work out is the pop when you step the counter (roll over a 10 ns boundary). The gizmo is cheap enough that you run two of them and ping-pong when you do a roll over (keep one running while the other settles). The big bucks approach probably is to run a good RF ADC on the input and then do all the offset stuff as DSP math. The VCXO just sits at it's magic frequency and never moves. More money / no pops. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of ewkeh...@aol.com Sent: Monday, October 22, 2012 7:05 AM To: time-nuts@febo.com Subject: Re: [time-nuts] Adjusting HP 5065A frequency Tom I have two questions what should the range, resolution and stability of the delay generator be and how much do you think a digital loop driven by a Tbolt would degrade short and medium precision. What is your definition of short and medium? Bert Kehren In a message dated 10/22/2012 12:25:08 A.M. Eastern Daylight Time, t...@leapsecond.com writes: Three companies come to mind for phase microsteppers. A popular one decades ago was made by Austron (model 2055A). I got mine on eBay but they are not as common now as ten years ago. The current models by Symmetricom and Spectra Dynamics are extremely high-end (expensive) and overqualified for use with a vintage rubidium oscillator. If you visit NIST or USNO you will see these impressive units. It would be a very fun project to make your own. I suspect other group members could either help you or would eagerly employ your design for their own use. But -- before you decide on a hardware solution see if you can do it in software. An analogy is what we do with GPS 1PPS sawtooth errors. There are two ways to deal with this. One is to capture the correction message over RS232, measure the DUT vs. GPS 1PPS with a TIC, and then numerically apply the sawtooth correction with one line of code. Several of the popular GPS monitor programs do this automatically for you (TBoltmon and TAC32, for example). The software solution is perfect to the granularity of the sawtooth message, typically 1 ns. The hardware implementation usually involves a PIC and a programmable delay generator. The PIC listens for the correction message over RS232 and then has plenty of time (up to one second) to program the delay chip. When the hardware 1PPS arrives it is delayed to compensate for the aforementioned sawtooth error. The result is a hardware 1PPS that's quite close to the ideal 1PPS, limited again by the granularity of the message, as well as offset or linearity errors in the delay chip. So that's the analogy. To apply this to your rubidium, ask yourself which instruments or measurements or users are downstream of your 5065A 10 MHz output. Can they deal with daily software corrections to a stable but slightly imprecise frequency, or do they really need the frequency to be as accurate as possible at all times. There's a third alternative as well. You might consider using your 5065A as the LO in a GPSDO. This will sacrifice some short- and mid-term precision due to additive noise, but it will guarantee the best possible long-term accuracy. /tvb - Original Message - From: Edgardo Molina To: Tom Van Baak ; Discussion of precise time and frequency measurement Sent: Sunday, October 21, 2012 8:49 PM Subject: Re: [time-nuts] Adjusting HP 5065A frequency Dear Tom, Good evening. In relation to your last comments on this and other subjects, I am sharing some thoughts and experience about it. I took the liberty to separate the topics as to ease the interested parties to follow up accordingly. TNX. a. Information you kindly provided and the index for newbies: Thank you! You just provided me with lots of new ideas and information on the subject. You have very valuable information in your web site. As Hal was saying, an index should be done anywhere so it could
Re: [time-nuts] Adjusting HP 5065A frequency
There's a history to many of the GPSDO products you hear us talk about. I believe the original TBolt (fancy red case) did have an OCXO but it wasn't particularly high quality. Perhaps Bob can shed light on this. 99% of TBolt's found on the surplus market today, and all the ones in the TAPR deal, have a surprisingly good OCXO's. These were customer specials as best we can determine, and never described on Trimble's web page. They are in the plain brushed golden color aluminum case. The Thunderbolt E is a relatively new product (fancy blue case, ROHS-compliant) and isn't yet on the surplus market. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Adjusting HP 5065A frequency
Hi Based on Time Nuts data - The OCXO's in the TBolt's have indeed gotten better over the years. The early Piezo labeled parts did not do as well as the later Trimble labeled parts. With the Trimble labeled parts, roughly pre-2002 is a break point for performance. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van Baak Sent: Monday, October 22, 2012 1:00 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Adjusting HP 5065A frequency There's a history to many of the GPSDO products you hear us talk about. I believe the original TBolt (fancy red case) did have an OCXO but it wasn't particularly high quality. Perhaps Bob can shed light on this. 99% of TBolt's found on the surplus market today, and all the ones in the TAPR deal, have a surprisingly good OCXO's. These were customer specials as best we can determine, and never described on Trimble's web page. They are in the plain brushed golden color aluminum case. The Thunderbolt E is a relatively new product (fancy blue case, ROHS-compliant) and isn't yet on the surplus market. /tvb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ? (Dale J. Robertson)
On Mon, Oct 22, 2012 at 02:16:19AM -0400, johncr...@aol.com wrote: Dale - To your question re BPSK and DPSK. In both modes the phase shift is 180 degrees. Straight PSK has the issue of determining the 1's from the 0's, at the receiver as there is no phase reference. To avoid this DPSK encodes the the serial data stream prior to the bi-phase modulator. As I recall (at 1 AM) the method is like this. If the present bit to be sent is a 1 the phase of the carrier is inverted. If it is a zero the phase is not inverted. This is easily sorted out in the receiver using a flip flop and an XOR. I might add one note. Non differential PSK has a slight BER advantage with very weak signals as differential PSK decoding causes TWO bits to be in error in the recovered data if the phase state of a bit is incorrectly determined by the receiver and the next and previous bits were correctly determined. For this reason most satellite nPSK modulations use absolute encoding and determine phase in initial lockon by looking for a phase which causes the inner FEC to work (eg produce valid corrected data). There have been demodulators for differential nPSK that work by correlating the last bit with the current bit using some kind of delay line. Don't typically work as well with weak signals though. -- Dave Emery N1PRE/AE, d...@dieconsulting.com DIE Consulting, Weston, Mass 02493 An empty zombie mind with a forlorn barely readable weatherbeaten 'For Rent' sign still vainly flapping outside on the weed encrusted pole - in celebration of what could have been, but wasn't and is not to be now either. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Adjusting HP 5065A frequency
On 22 Oct, 2012, at 12:48 , Bob Camp li...@rtty.us wrote: The big bucks approach probably is to run a good RF ADC on the input and then do all the offset stuff as DSP math. The VCXO just sits at it's magic frequency and never moves. More money / no pops. A somewhat cheaper way might be to use a DDS. That is, lock the clock driving the DDS to the input frequency and then program the DDS to correct the measured error of the input clock. A DDS with a 48 bit control word will have an effective resolution of about 4e-15, if my arithmetic is right, which seems adequate for the purpose. The DDS also gives you the option of generating any (corrected) output frequency you want. The output frequency could even be programmable if you don't mind looking at the DDS digital noise in the output, though that could be cleaned up by picking a fixed output frequency ahead of time and adding a cleanup PLL for the chosen frequency following the DDS. I'm not sure why this problem isn't always dealt with this way, actually. Since the corrections are applied in digital arithmetic the precision with which they can be made is limited only by the bit-width of the adders you use to compute each cycle's update and, given that the D/A converter it is driving is probably going to be limited to 300 or 400 MSPS, even an FPGA (let alone semi-custom logic) could carry more bits through the computation than are useful to have. There is probably some catch to this that I don't understand. Dennis Ferguson ___ time-nuts mailing 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] Adjusting HP 5065A frequency
Hi The gotcha with the DDS is phase truncation. That pretty much trashes the ADEV. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Dennis Ferguson Sent: Monday, October 22, 2012 1:44 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Adjusting HP 5065A frequency On 22 Oct, 2012, at 12:48 , Bob Camp li...@rtty.us wrote: The big bucks approach probably is to run a good RF ADC on the input and then do all the offset stuff as DSP math. The VCXO just sits at it's magic frequency and never moves. More money / no pops. A somewhat cheaper way might be to use a DDS. That is, lock the clock driving the DDS to the input frequency and then program the DDS to correct the measured error of the input clock. A DDS with a 48 bit control word will have an effective resolution of about 4e-15, if my arithmetic is right, which seems adequate for the purpose. The DDS also gives you the option of generating any (corrected) output frequency you want. The output frequency could even be programmable if you don't mind looking at the DDS digital noise in the output, though that could be cleaned up by picking a fixed output frequency ahead of time and adding a cleanup PLL for the chosen frequency following the DDS. I'm not sure why this problem isn't always dealt with this way, actually. Since the corrections are applied in digital arithmetic the precision with which they can be made is limited only by the bit-width of the adders you use to compute each cycle's update and, given that the D/A converter it is driving is probably going to be limited to 300 or 400 MSPS, even an FPGA (let alone semi-custom logic) could carry more bits through the computation than are useful to have. There is probably some catch to this that I don't understand. Dennis Ferguson ___ time-nuts mailing 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] Adjusting HP 5065A frequency
On Mon, Oct 22, 2012 at 1:00 PM, Tom Van Baak t...@leapsecond.com wrote: There's a history to many of the GPSDO products you hear us talk about. I believe the original TBolt (fancy red case) did have an OCXO but it wasn't particularly high quality. Perhaps Bob can shed light on this. 99% of TBolt's found on the surplus market today, and all the ones in the TAPR deal, have a surprisingly good OCXO's. These were customer specials as best we can determine, and never described on Trimble's web page. They are in the plain brushed golden color aluminum case. The T'bolts in the gold, brushed aluminum case were provided to Grayson Electronics, at the time a part of the Allen Group (later Andrew and Commscope) for use in a receiver for an E911 locator system. The Trimble p/n was 41562-30 and, as far as I know, the only significant changes are the value of one Zener to allow the -12 V line to run at -7 V w/o asserting a fault and the change of the power connector to the back side of the board. Only the board is from Trimble; the sheetmetal and the attached 3dB coupler were provided by the OEM. Otherwise, I believe it to be the same unit that was in the red and silver Trimble case being sold at the same time (the one with the integrated dc-dc converters). 73, geo - n4ua ___ time-nuts mailing 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] documentation for beginners (was: Followup (still want a GPS-type NTP refclock))
Yes, the problem is that I don't have anything running NTP... I'm searching for a packet dump: I should use it to quickly develop the response for a possible Lantronix XPort implementation. On Mon, Oct 22, 2012 at 6:22 PM, Hal Murray hmur...@megapathdsl.net wrote: azelio.bori...@screen.it said: And don't forget those NTP people. BTW, is there an NTP packet exchange example? That is, what is the typical conversation between an NTP server and a client? What are you looking for? The wikipedia page is a good introduction: http://en.wikipedia.org/wiki/Network_Time_Protocol NTP is a big sub-set of time-nut activity with an active community of geeks. I think any time-nut documentation should point to other info rather than duplicate their activity. http://www.ntp.org/ There is also PTP, IEEE 1588 The basic NTP conversation is the typical client/server exchange of a pair of UDP packets. tcpdump will decode the contents so you can easily use it to get a quick introduction. (That's assuming you have a system running NTP that already generates the packets.) -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP Z3805A com port and monitoring questions
On 10/22/2012 07:13 AM, Tom Van Baak wrote: Trimble and HP took different approaches on their GPSDO's. Trimble lets you get into things and fiddle around. HP is much more a black box. I have never seen anything that lets you fiddle' with one of the HP units. Hi Bob, I'm glad you asked. True, the Trimble TSIP binary command set lets you fiddle and the HP SCPI command set is much easier to use but more limited by comparison. But there's also a rich under-the-hood layer on the HP units. Spend some time with this file and you'll see what I mean: http://leapsecond.com/museum/z3801a/z3801a-bin.txt I explored the functionality in some detail during my hp GPSDO DAC dither investigation some years ago. Contact me offline. I spend time to reverse engineer it, and there is a whole bunch of hidden features which isn't in the documentation. Among others, you can get the list of the pSOS processes. There's also a pForth in there, so if you kick the right escape sequence you get into a Forth prompt, but I don't remember how much of the inner gut you get through it. There is *MUCH* more under the Z38xx hood! I would need to have pSOS manuals for the 68k variant to get further. The Trimble approach is a tuneable PI-based PLL. Nothing wrong with that. HP went for the Smart Clock approach out of NIST. The Trimble approach is a platform where the openness allowed for the customer to adapt to its application (and alternative oscillators) while the HP approach was to achieve a well-engineered solution. What Trimble did right is that they tuned up the GPS receivers oscillator while HP spent more on the control algorithms. It's not all, but a quick stab at the differences. 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.
Re: [time-nuts] Adjusting HP 5065A frequency
Bert, On 10/22/2012 04:46 PM, ewkeh...@aol.com wrote: Tom A good place to start is with a manual of the Austron 2055 delay if there is real interest. Does any one have it in PDF form? As to the disciplining a Rb or specifically a HP5065A, the filter part is the challenge. Having worked on it for the last ten years always using Brooks loop and developing work around's it will do every thing except temperature control and barometric pressure. I have done temperature analog but rely mainly on holding the Rb temperature stable within a tenth degree C. Bob recently put things in perspective when there was talk about a 32 bit DAC. On one side you have GPS and time averaging is required to get full use of it. That is why a Rb is uniquely qualified for it. The original Shera input implemented on a 1 $ G/A is more than enough for time capture wether using a sawtooth corrected GPS receiver or a Tbolt. On the other end a LTC1655 is again more than enough in an Rb application. You can use it 16 bit direct or dither two or 4 bits. Filter is easy and do not forget that the Rb has an additional filter between cell and OCXO. Brooks V402NE will do the job, how ever others and I have not been able to buy some in the last nine month. Any one knows what is going on? What is needed is some one in the group be willing and able to step up to the plate and develop the filter on a PIC with all the things learned, and believe me, we are still learning as we adapt a M100/8600 via a Tbolt . I will be willing to help with every thing except the PIC. If you bring out the C field coil directly you have full isolation and do not have to worry about ground loops. A complete unit would cost less than $ 40 and more important be assembled by any one. I brought it up before but no one responded. If no response I will still be able to do every thing with the HP5065A RVFR that was given to me. The needed loop filter isn't all that hard to achieve. Do read the Stanford Research PRS-10 manual. The core PI-filter can be formulated as: VI = VI + Vd * I VF = VI + Vd * P Where Vd is the phase detector value (may be in number of nanoseconds or whatever), VF is the output frequency control (EFC) value. The I and P values is the control parameters and VI is the integrator state. Adding a pre-filter for Vd values can be done as in the PRS-10: Vd = Vd + (Vi - Vd)* F where Vi is the raw input and F is filter control parameter. F can be set in power of 2 steps without too much loss of control, allowing for shift-steps, which is what the PRS-10 uses. The PRS-10 runs it all in a whopping 6805 if I recall things correctly, just your off the shelf 8 bit processor that felt right in the moment. You can then allow for some front-end processing to cook up the I and P values from more user-friendly parameters if you like. Tossing in a FLL functionality on top of it for improved lock-in performance isn't hard either. There is a few scaling issues and most things is about getting a stable timing and such, but it's not all that hard. If you want to do PPS there is a little more attention to lock-in details naturally. Cooking up an open lock-it-all isn't that hard thing to accomplish with a bit of knowledge and experience. One might even have a bit of fun and cook up a Kalman filter, which is essentially a self-tuning PI regulator. PS. Sorry for not making you aware in advance that I was changing planes in Miami this Friday. It was a busy week in Atlanta. 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.
Re: [time-nuts] Adjusting HP 5065A frequency
On 10/22/2012 07:53 PM, Bob Camp wrote: Hi The gotcha with the DDS is phase truncation. That pretty much trashes the ADEV. True, but the more bits you apply the better performance you get. Modern DDS clock chips do have pretty amazing specs for the money you spend. 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.
Re: [time-nuts] HP Z3805A com port and monitoring questions
David, On 10/22/2012 08:07 AM, David Hooke wrote: Tom, It looks like they have a pForth interpreter running in there under PSOS: http://code.google.com/p/pforth/. That's not the pForth implementation in there I beleive. It's pretty close thought. Is there a mechanism to switch from SCPI to the Forth interpreter? Yes. I did reverse engineer that a few years back. It will take some time to recover. 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.
Re: [time-nuts] Adjusting HP 5065A frequency
Magnus Are you changing or did you change and if you are how much time do you have. Bert In a message dated 10/22/2012 6:24:06 P.M. Eastern Daylight Time, mag...@rubidium.dyndns.org writes: Bert, On 10/22/2012 04:46 PM, ewkeh...@aol.com wrote: Tom A good place to start is with a manual of the Austron 2055 delay if there is real interest. Does any one have it in PDF form? As to the disciplining a Rb or specifically a HP5065A, the filter part is the challenge. Having worked on it for the last ten years always using Brooks loop and developing work around's it will do every thing except temperature control and barometric pressure. I have done temperature analog but rely mainly on holding the Rb temperature stable within a tenth degree C. Bob recently put things in perspective when there was talk about a 32 bit DAC. On one side you have GPS and time averaging is required to get full use of it. That is why a Rb is uniquely qualified for it. The original Shera input implemented on a 1 $ G/A is more than enough for time capture wether using a sawtooth corrected GPS receiver or a Tbolt. On the other end a LTC1655 is again more than enough in an Rb application. You can use it 16 bit direct or dither two or 4 bits. Filter is easy and do not forget that the Rb has an additional filter between cell and OCXO. Brooks V402NE will do the job, how ever others and I have not been able to buy some in the last nine month. Any one knows what is going on? What is needed is some one in the group be willing and able to step up to the plate and develop the filter on a PIC with all the things learned, and believe me, we are still learning as we adapt a M100/8600 via a Tbolt . I will be willing to help with every thing except the PIC. If you bring out the C field coil directly you have full isolation and do not have to worry about ground loops. A complete unit would cost less than $ 40 and more important be assembled by any one. I brought it up before but no one responded. If no response I will still be able to do every thing with the HP5065A RVFR that was given to me. The needed loop filter isn't all that hard to achieve. Do read the Stanford Research PRS-10 manual. The core PI-filter can be formulated as: VI = VI + Vd * I VF = VI + Vd * P Where Vd is the phase detector value (may be in number of nanoseconds or whatever), VF is the output frequency control (EFC) value. The I and P values is the control parameters and VI is the integrator state. Adding a pre-filter for Vd values can be done as in the PRS-10: Vd = Vd + (Vi - Vd)* F where Vi is the raw input and F is filter control parameter. F can be set in power of 2 steps without too much loss of control, allowing for shift-steps, which is what the PRS-10 uses. The PRS-10 runs it all in a whopping 6805 if I recall things correctly, just your off the shelf 8 bit processor that felt right in the moment. You can then allow for some front-end processing to cook up the I and P values from more user-friendly parameters if you like. Tossing in a FLL functionality on top of it for improved lock-in performance isn't hard either. There is a few scaling issues and most things is about getting a stable timing and such, but it's not all that hard. If you want to do PPS there is a little more attention to lock-in details naturally. Cooking up an open lock-it-all isn't that hard thing to accomplish with a bit of knowledge and experience. One might even have a bit of fun and cook up a Kalman filter, which is essentially a self-tuning PI regulator. PS. Sorry for not making you aware in advance that I was changing planes in Miami this Friday. It was a busy week in Atlanta. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Adjusting HP 5065A frequency
Hi Modern parts are pretty cool. I have measured them them for this application. The truncation still is a big issue. Bob On Oct 22, 2012, at 6:16 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 10/22/2012 07:53 PM, Bob Camp wrote: Hi The gotcha with the DDS is phase truncation. That pretty much trashes the ADEV. True, but the more bits you apply the better performance you get. Modern DDS clock chips do have pretty amazing specs for the money you spend. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Adjusting HP 5065A frequency
Warren, On 10/23/2012 12:45 AM, WarrenS wrote: Tom said: In general, when you discipline a OCXO you get that characteristic ADEV hump. At some point there is a cross-over and you know/assume that at that point each must be contributing 1/sqrt(2) of the noise. Although putting the Hump at the cross over point is typically a good compromise, there are other choices which give different trade-offs. Attached is a excell plot showing the effect of different PID tunings on the Hump's size and location. This spread sheet (originally is from Wenzel's site) was for plotting the effect of the RC H/W values for a PLL when used as a clean up Osc, but can be used for setting the PID values of a disciplined GPS such as a Tbolt with a few changes and using different data. As expected, the hömp (sorry for sudden Inspector Clouseau) depends greatly on the damping factor. Lowest hump you get from the high damping-factor (40) located at the cross-over point of the two curves. The remaining hump is what you need to live with as the noises is spliced together by the high-pass/low-pass action of the PLL. Good illustration. I haven't seen it before, but it is expected. 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.
Re: [time-nuts] Adjusting HP 5065A frequency
On 10/23/2012 12:41 AM, Bob Camp wrote: Hi Modern parts are pretty cool. I have measured them them for this application. The truncation still is a big issue. If you generate a lower frequency and gear it up in frequency, you would get better result. It's more or less what the phase micro-steppers do anyway. IEM Kvarz also makes micro-stepper BTW. 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.
Re: [time-nuts] Adjusting HP 5065A frequency
Hi Yes, a DDS at high freq./ narrow band crystal filter / divide to low audio / image reject mix with input back to rf / lock to VCXO approach would get around much (but not quite all) of the truncation stuff. It's complex enough that I suspect that ADC approach would give it a run for the money ( equal to, or better than bang for the buck). Bob On Oct 22, 2012, at 7:18 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote: On 10/23/2012 12:41 AM, Bob Camp wrote: Hi Modern parts are pretty cool. I have measured them them for this application. The truncation still is a big issue. If you generate a lower frequency and gear it up in frequency, you would get better result. It's more or less what the phase micro-steppers do anyway. IEM Kvarz also makes micro-stepper BTW. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ?
Dale I guess a couple of comments to you and everyone. I am not an expert on the chip. I downloaded what was available and thats not all that much. So if someone has the experience to know whats actually correct and how to turn this magical 20 cent chip into something useful, I am all ready to hear the answer. I do not believe that the system uses a varicap or VTO to tune things instead I will speculate they drop cycles in the count chain. But thats simply a guess. No matter what I simply could not get the system to put out the 1s and 0s I was putting in. But spent only a few nights on it because the reality is its only a part of the answer. The costas loop is the nice piece. But ahead of that it needs a somewhat healthy signal to drive it so there is more to the puzzle like agc and such. To the easier part of your 2 questions. The BPSK modulator was reasonable. It can be created a lot of ways but we are talking 60Khz and that opens up things like opamps etc. But real simple. I take a 60 khz sig generator, locked to a RB reference at 1 volt pp. Run that to a xformer primary. These are radioshack class they work great at 60 Khz who would have thought. The secondary center tap is grounded and I select plus or minus phase with a CD 4016 analog switch. Using a single supply everything is biased at 1/2 VCC and then isolation caps for the signals. To switch correctly at the zero point I sample the plus of the secondary with a LM339 comparator (only using 1 section) and feed that to a SXB micro running at 40 Mhz. Detect the zero and switch if I want. The micro programs in basic and screams along. So I can flip at any rate or create patterns as easily as I can think them up. Its seriously dumb, simple, and stupid. But it lets me run tests without waiting for wwvb. I do attenuate the output signal to about 60 uv. Generally what I see on the east coast during the day. Regards Paul WB8TSL On Mon, Oct 22, 2012 at 9:18 AM, Dale J. Robertson d...@nap-us.com wrote: Paul, I would also be interested in how you built your simulator. I'm considering building a simple one myself. I'll probably have mine just toggle the phase every 100 ms initially. Dale -Original Message- From: paul swed Sent: Sunday, October 21, 2012 11:08 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ? Jameco had them on sale for 20 cents each so I purchased some. Moved the clock up frequency for 60 Khz and injected the 60Khz BPSK. (I built a simulator) It did not track and in general produced noise. I understand you can use 2 frequencies to drive it and I tried both from synth gens. I was looking at the RDS decoders and the data seemed to be differential. Set it aside at that point. I am curious as to why it did not work. Like everyone here would be great if it worked Regards Paul WB8TSL On Sun, Oct 21, 2012 at 10:55 PM, Dale J. Robertson d...@nap-us.com wrote: Paul, I'm trying to understand your reference to 'differential BPSK' all the RDS references I've looked at indicate a 180 degree phase shift just like WWVB. I'm thinking that differential and antipodal are just different words for the same thing Regards, Dale Sent from my iPhone On Oct 21, 2012, at 10:03 PM, paul swed paulsw...@gmail.com wrote: Because it use differential BPSK. I have a number of them and was trying it. There is a test pin that might make it useful. Regards Paul WB8TSL On Sun, Oct 21, 2012 at 9:14 PM, Dale J. Robertson d...@nap-us.com wrote: While looking for other stuff I came across the data sheet for the NXP Semi SAA6579. The chip is a purpose built demodulator for RDS (which utilises a 57 KHz ABPSK subcarrier on FM broadcast that is) used for traffic, song info etc. This chip has an anti-aliasing front end low pass filter and an 8th order bandpass filter followed by a costas loop and provides a phase synchronous regenerated carrier. What's interesting is that the switched cap bandpass filter and the synchronous detector are both driven by clocks derived from a local crystal oscillator which is spec'd at 4.332 or 8.664 MHz (76 or 152 X carrier chosen by a mode select pin) I'm thinking it should be possible to use a 4.56 or 9.12 MHz crystal or external clock to use this chip as-is on 60 KHz. Have a look at the data sheet and tell me why I'm full of it. Jameco is closing out these chips in DIP-16 at a nickel apiece, $3.00/hundred. Dale NV8U ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/https://www.febo.com/cgi-bin/** mailman/listinfo/time-nuts https://www.febo.com/cgi-bin/**mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ?
- Original Message - From: paul swed paulsw...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, October 22, 2012 8:35 PM Subject: Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ? To switch correctly at the zero point I sample the plus of the secondary with a LM339 comparator (only using 1 section) and feed that to a SXB micro running at 40 Mhz. Detect the zero and switch if I want. The micro programs in basic and screams along. So I can flip at any rate or create patterns as easily as I can think them up. Its seriously dumb, simple, and stupid. But it lets me run tests without waiting for wwvb. I do attenuate the output signal to about 60 uv. Generally what I see on the east coast during the day. Hi Paul, Reading the spec, I think the chip wants to see about 500 UV RMS. Is that correct? At three cents each, it sure would be nice to find another use for it. ___ time-nuts mailing 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] WWVB New Modulation five cent demodulator / carrier regenerator ?
I was giving it 1000uv. Thats why I say it needs a lot. On Mon, Oct 22, 2012 at 9:00 PM, Tom Miller tmil...@skylinenet.net wrote: - Original Message - From: paul swed paulsw...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Monday, October 22, 2012 8:35 PM Subject: Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier regenerator ? To switch correctly at the zero point I sample the plus of the secondary with a LM339 comparator (only using 1 section) and feed that to a SXB micro running at 40 Mhz. Detect the zero and switch if I want. The micro programs in basic and screams along. So I can flip at any rate or create patterns as easily as I can think them up. Its seriously dumb, simple, and stupid. But it lets me run tests without waiting for wwvb. I do attenuate the output signal to about 60 uv. Generally what I see on the east coast during the day. ==**== Hi Paul, Reading the spec, I think the chip wants to see about 500 UV RMS. Is that correct? At three cents each, it sure would be nice to find another use for it. __**_ 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/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.
