Re: [time-nuts] Recommendations for a newbie?
Said wrote: you make and post negative assumptions about a seller without any first hand experience * * * It is unfair to post that kind of negative opinion without you having any first hand experience with them. This is already way out of hand -- so with this, I'm done: I think you are over-reading my comments, intent on finding offense where none was given. Please recognize that in the process, you are making and posting unfounded negative assumptions about me, the assumptions you assume that I have made, and my postings -- precisely what you accuse me of. I reiterate that I said (and certainly, I meant) nothing negative about the seller, and made no negative assumptions and no negative comments. In fact, I do have experience with him and have no complaints. My point was not that one might not get what was described; rather, it was that I cannot tell from the 58503A listings exactly what is being described, or how what is described in one listing differs from what is described in other listings that vary considerably in price. Nothing more. The End, 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] Recommendations for a newbie?
Hi Bob, On 09/09/2012 03:55 AM, Bob Camp wrote: Hi It would be nice if somebody came up with a fast port adaptation to one of the standard data collection programs. It would not be all that hard to do an adaptation board which creates a live USB stream for instance. Either using an FPGA or by using a handful of TTL and a Cypress USB chip. What you get is the unprocessed hardware time-stamps, but if you add a driver that does the processing (and the HP5372A Programming manual is really getting you into the gory details of bits and post-processing!) then having Timelab do it should not be too hard. It's on my list of neat things to do, but I have so many other things to do. If someone tries to do it, let me know. BTW, I happen to enable the Fast Port on my HP5372A. :) 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] GPSDO Component Selection
Hello, I would like to design and build a microcontroller based GPSDO. And I have a couple of questions some of you may be able to answer. 1. I am going to use Trimble SMT GPS timing module but I'm curious. Does a GPS timing receiver produce a more precise 1 PPS output than a standard GPS tracking receiver in a static location? Or does it just produce a 1 PPS signal that is more accurate to GPS time? 2. I have seen many DOCOXs' listed on eBay produced by Morion Inc St Petersburg Russia. This includes models MV89 and MV180 with manufacture dates in 2008. All of the Ox's' were removed from equipment. I don't know anything about Morion's reputation. The specifications are very good, but do they live up to their data sheet, are they reliable and stable? What DOCXOs' would you recommend? Thanks in advance Don O'Connor ___ time-nuts mailing 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] New wrist Watch
Hello The Net: I need to consider getting a new wrist watch, but I need a second hand and a digital display is unacceptable. What would you consider in the 150$ price range ? Would be nice to have state of the art accuracy with a lifetime battery and high reliability. Thanks, Stan, W1LE Cape CodFN41sr ___ time-nuts mailing 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 wrist Watch
On 9/9/12 7:05 AM, Stan, W1LE wrote: Hello The Net: I need to consider getting a new wrist watch, but I need a second hand and a digital display is unacceptable. What would you consider in the 150$ price range ? Thunderbolt driving a stepper motor? Would be nice to have state of the art accuracy with a lifetime battery and high reliability. Oh.. the battery will weigh a huge amount, but it will last a lifetime, because yours will be very short carrying it It won't be state of the art (I think tvb's cesium wrist watch does that.. but it doesn't have the non-digital display you want) grin couldn't resist... ___ time-nuts mailing 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 wrist Watch
On 09/09/2012 07:05 AM, Stan, W1LE wrote: Hello The Net: I need to consider getting a new wrist watch, but I need a second hand and a digital display is unacceptable. What would you consider in the 150$ price range ? Would be nice to have state of the art accuracy with a lifetime battery and high reliability. Thanks, Stan, W1LE Cape CodFN41sr ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Since the determining factor in the accuracy of a wrist watch these days is you reaction time in setting it to the announcements on WWV, I'd go to Walmart or Target and find something cheap. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ time-nuts mailing 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 wrist Watch
Just do a Google image search for analog atomic watch. Pick the one you like. There are several in the $50-$60 price range that are attractive. Many are solar so there are no batteries to replace. They're all set by WWVB nightly (usually) so they're well within a second of accuracy. -Bob On Sun, Sep 9, 2012 at 8:05 AM, Stan, W1LE stanw...@verizon.net wrote: Hello The Net: I need to consider getting a new wrist watch, but I need a second hand and a digital display is unacceptable. What would you consider in the 150$ price range ? Would be nice to have state of the art accuracy with a lifetime battery and high reliability. Thanks, Stan, W1LE Cape CodFN41sr ___ time-nuts mailing 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 Component Selection
On Sun, Sep 9, 2012 at 6:18 AM, Don Oconnor eg...@wowway.com wrote: Hello, I would like to design and build a microcontroller based GPSDO. And I have a couple of questions some of you may be able to answer. 1. I am going to use Trimble SMT GPS timing module but I'm curious. Does a GPS timing receiver produce a more precise 1 PPS output than a standard GPS tracking receiver in a static location? Or does it just produce a 1 PPS signal that is more accurate to GPS time? Both of the above by several orders of magnitude. The best timing mode GPSes today have the PPS within a few tens of nanoseconds of UTC (one sigma) while the typical navigation mode GPS has the PPS within a few microseconds. Also the timing mode GPS can do things like a self survey to determine location. The finding a soltion for time within _knows_ it is not moving removes some uncertainty in the result. I'd say it would be almost pointless to use a nav receiver in a GPSDO especially when decent timming mode receivers sell for under $20. 2. I have seen many DOCOXs' listed on eBay produced by Morion Inc St Petersburg Russia. This includes models MV89 and MV180 with manufacture dates in 2008. All of the Ox's' were removed from equipment. I don't know anything about Morion's reputation. The specifications are very good, but do they live up to their data sheet, are they reliable and stable? Morion has a good reputation but like anything used from eBay expect unit to unit variation. Might be worth buying a few. Actually how else could you measure your GPSDO? I think the main thing that will determine performance is the phase detector that will compare 10MHz to 1Hz. That is your design and is the most critical part. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New wrist Watch
Stan, You want a Casio Waveceptor WVA470J-1ACF, ana-digi/solar/wwvb. I have a WVA105HDA-2A, no-solar, no sweep hand, been a solid performer. 73, Ed -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Stan, W1LE Sent: Sunday, September 09, 2012 10:06 AM To: time-nuts@febo.com Subject: [time-nuts] New wrist Watch Hello The Net: I need to consider getting a new wrist watch, but I need a second hand and a digital display is unacceptable. What would you consider in the 150$ price range ? Would be nice to have state of the art accuracy with a lifetime battery and high reliability. Thanks, Stan, W1LE Cape CodFN41sr ___ time-nuts mailing 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] HP10514B Mixer Terminations
Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) All your help will be appreciated Thanks in advance Pascual Arbona EA5JF ___ time-nuts mailing 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] HP10514B Mixer Terminations
Most all of this kinda stuff is built using 50 Ohm 'building blocks'. You can almost plug them together like Legos. The HP 10514A is no different: http://www.ko4bb.com/Manuals/HP_Agilent/HP_10514_Mixer_Jan_1967.pdf Mini-Circuits (among others) sells loads of different wsuch components. Your biggest choice may be the connector style. BNC and SMA are very common. If size/weight are not a consideration go BNC. -John === Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) All your help will be appreciated Thanks in advance Pascual Arbona EA5JF ___ time-nuts mailing 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] Recommendations for a newbie?
Charles, maybe I did read your email wrong, I apologize for that. To me it came across as negative toward the seller and the listings, and it seems this is not how it was meant, my appologies. Bye, Said In a message dated 9/8/2012 23:05:30 Pacific Daylight Time, charles_steinm...@lavabit.com writes: I reiterate that I said (and certainly, I meant) nothing negative about the seller, and made no negative assumptions and no negative comments. In fact, I do have experience with him and have no complaints. My point was not that one might not get what was described; rather, it was that I cannot tell from the 58503A listings exactly what is being described, or how what is described in one listing differs from what is described in other listings that vary considerably in price. Nothing more. The End, 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.
[time-nuts] RE; New Wrist watch
I have a $49 Casio Wave Ceptor, white face black numerals, analog hands including second hand, date, alarm and WWVB syncing in the middle of the night. Only had to replace the battery once and it ticks are closer than I can discern when comparing to WWV @ 10or 15 Mhz. Rich, W9ENG ___ time-nuts mailing 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] HP10514B Mixer Terminations
For this particular application a capacitive termination (NIST used such a termination in their DMTDs) of the IF port followed by a low pass filter is advantageous. For precision work screw connectors (SMA, TNC, N etc) are more stable than bayonet connectors like the BNC. Bruce J. Forster wrote: Most all of this kinda stuff is built using 50 Ohm 'building blocks'. You can almost plug them together like Legos. The HP 10514A is no different: http://www.ko4bb.com/Manuals/HP_Agilent/HP_10514_Mixer_Jan_1967.pdf Mini-Circuits (among others) sells loads of different wsuch components. Your biggest choice may be the connector style. BNC and SMA are very common. If size/weight are not a consideration go BNC. -John === Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) All your help will be appreciated Thanks in advance Pascual Arbona EA5JF ___ time-nuts mailing 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 Component Selection
Chris, On Sun, Sep 9, 2012 at 6:18 AM, Don Oconnor eg...@wowway.com wrote: Hello, I would like to design and build a microcontroller based GPSDO. And I have a couple of questions some of you may be able to answer. 1. I am going to use Trimble SMT GPS timing module but I'm curious. Does a GPS timing receiver produce a more precise 1 PPS output than a standard GPS tracking receiver in a static location? Or does it just produce a 1 PPS signal that is more accurate to GPS time? Both of the above by several orders of magnitude. The best timing mode GPSes today have the PPS within a few tens of nanoseconds of UTC (one sigma) while the typical navigation mode GPS has the PPS within a few microseconds. Also the timing mode GPS can do things like a self survey to determine location. The finding a soltion for time within _knows_ it is not moving removes some uncertainty in the result. I'd say it would be almost pointless to use a nav receiver in a GPSDO especially when decent timming mode receivers sell for under $20. True for a cheap oem navigation receiver. Not true for a geodetic quality receiver, who usually have some options (external frequency input, PPS_in) to make them the best timing receivers available. However they are much more expensive than the typical single frequency timing reciver. Look at: http://www.septentrio.com/products/receivers/polarx4-tr-pro http://www.topconpositioning.com/products/networks/network-systems/net-g3a http://www.novatel.com/solutions/timing/#whatWeOffer http://javad.com/downloads/javadgnss/sheets/Delta-G3T_Datasheet.pdf http://javad.com/downloads/javadgnss/how-to/hardware/Receiver_Clock_Synchronizing_Configuration_Example.pdf -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP10514B Mixer Terminations
On 9 September 2012 18:28, Pascual Arbona p.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. I don't know the details of what you are trying to do, but keep in mind what I said. 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] RE; New Wrist watch
The waveceptor's are okay but I can't wear mine much because I tend to cross timezones a lot. The hands only run in one direction so when going to the west, it has to spin 11 hours forward. This takes 20 minutes. I guess it's one way to kill time on an airplane. -Bob On Sun, Sep 9, 2012 at 1:12 PM, Rich and Marcia Putz rp...@bnin.net wrote: I have a $49 Casio Wave Ceptor, white face black numerals, analog hands including second hand, date, alarm and WWVB syncing in the middle of the night. Only had to replace the battery once and it ticks are closer than I can discern when comparing to WWV @ 10or 15 Mhz. Rich, W9ENG ___ time-nuts mailing 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] HP10514B Mixer Terminations
David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. 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. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO Component Selection
On Sun, Sep 9, 2012 at 1:14 PM, b...@lysator.liu.se wrote: True for a cheap oem navigation receiver. Not true for a geodetic quality receiver, who usually have some options (external frequency input, PPS_in) to make them the best timing receivers available. However they are much more expensive than the typical single frequency timing reciver. I looked at every link and can't see where they give a timing accuracy spec on the PPS with respect to UTC. Possition accurracy is very good and we might assume the timing is as good. But they don't say it is. What's interesting is these GPSes will accept an accurate clock input in order to give better location data. That is the opposite of a timing GPS where you tell it accurate location data so that it can get better timing. Cutting down the unknown in one lets you do better in the other. I assume these all cost well over $50. You can get a pretty good timing GPS for $30 and it WILL have the PPS error specified. To the OP. None of this matters a lot because PPS is a standard input signal. It is easy to swap out a GPS receiver later. Same with the OCXO. From a control point of view they are all pretty much the same. You can swap them out later 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.
Re: [time-nuts] RE; New Wrist watch
I have a Junghans. I can't say it is easy on the batteries. Otherwise they work. I regret not getting the glows in the dark version. ___ time-nuts mailing 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] HP10514B Mixer Terminations
Bruce is correct. For best RF performance in an rf environment the use of 50ohms for all ports is a good start. However, even in RF designs you can often optimise a mixer spec with something other than 50 ohms. With a VLF IF freq like a DMTD, each mixer model might have an ideal termination impedance. Steve Mass' book on RF mixers is good for typical mixer applications but the NIST papers are better for DMTD uses. In the mm-wave work I have done, the first place to start is to increase LO power until the s11 of the IF port starts to look like a good match for the IF pre-amp. So each application of a mixer can often be based around what you are doing with it. Each time I use one, I learn a new fact! :-). Great hobby! -Brian, WA1ZMS/4 On Sep 9, 2012, at 4:41 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. 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. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP10514B Mixer Terminations
Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. 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. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO Component Selection
Hi Position accuracy and timing accuracy are two very different things. Firmware is optimized to improve either one. Position firmware is often pretty poor for timing. Bob On Sep 9, 2012, at 5:05 PM, Chris Albertson albertson.ch...@gmail.com wrote: On Sun, Sep 9, 2012 at 1:14 PM, b...@lysator.liu.se wrote: True for a cheap oem navigation receiver. Not true for a geodetic quality receiver, who usually have some options (external frequency input, PPS_in) to make them the best timing receivers available. However they are much more expensive than the typical single frequency timing reciver. I looked at every link and can't see where they give a timing accuracy spec on the PPS with respect to UTC. Possition accurracy is very good and we might assume the timing is as good. But they don't say it is. What's interesting is these GPSes will accept an accurate clock input in order to give better location data. That is the opposite of a timing GPS where you tell it accurate location data so that it can get better timing. Cutting down the unknown in one lets you do better in the other. I assume these all cost well over $50. You can get a pretty good timing GPS for $30 and it WILL have the PPS error specified. To the OP. None of this matters a lot because PPS is a standard input signal. It is easy to swap out a GPS receiver later. Same with the OCXO. From a control point of view they are all pretty much the same. You can swap them out later Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO Component Selection
Sounds like the Heisenberg Uncertainty principle at work :-) jerry -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Sunday, September 09, 2012 5:53 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPSDO Component Selection Hi Position accuracy and timing accuracy are two very different things. Firmware is optimized to improve either one. Position firmware is often pretty poor for timing. Bob On Sep 9, 2012, at 5:05 PM, Chris Albertson albertson.ch...@gmail.com wrote: On Sun, Sep 9, 2012 at 1:14 PM, b...@lysator.liu.se wrote: True for a cheap oem navigation receiver. Not true for a geodetic quality receiver, who usually have some options (external frequency input, PPS_in) to make them the best timing receivers available. However they are much more expensive than the typical single frequency timing reciver. I looked at every link and can't see where they give a timing accuracy spec on the PPS with respect to UTC. Possition accurracy is very good and we might assume the timing is as good. But they don't say it is. What's interesting is these GPSes will accept an accurate clock input in order to give better location data. That is the opposite of a timing GPS where you tell it accurate location data so that it can get better timing. Cutting down the unknown in one lets you do better in the other. I assume these all cost well over $50. You can get a pretty good timing GPS for $30 and it WILL have the PPS error specified. To the OP. None of this matters a lot because PPS is a standard input signal. It is easy to swap out a GPS receiver later. Same with the OCXO. From a control point of view they are all pretty much the same. You can swap them out later Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] HP10514B Mixer Terminations
NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. NIST used a simple diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst using a reactive termination for the difference frequency. With such a termination the minicircuits phase detectors had lower measured PN noise than the 10514. Another issue to consider is saturated or unsaturated (linear) operation of the mixer. Saturated operation, for most mixers, produces lower noise (flicker and floor) however linear operation can have for some mixers lower phase shift tempco which can be important depending on the environment and required phase shift stability. Bruce Bob Camp wrote: Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. 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. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] HP10514B Mixer Terminations
In the late 60s I built a VLF upconverter using a ring mixer. I tried a few different devices for the diodes. The base/collector junctions of germanium switching transistors gave the best results. On 09/09/2012 03:21 PM, Bruce Griffiths wrote: NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. NIST used a simple diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst using a reactive termination for the difference frequency. With such a termination the minicircuits phase detectors had lower measured PN noise than the 10514. Another issue to consider is saturated or unsaturated (linear) operation of the mixer. Saturated operation, for most mixers, produces lower noise (flicker and floor) however linear operation can have for some mixers lower phase shift tempco which can be important depending on the environment and required phase shift stability. Bruce Bob Camp wrote: Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. 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. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chuck Forsberg WA7KGX N2469R c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ time-nuts mailing 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] HP10514B Mixer Terminations
On 09/10/2012 12:21 AM, Bruce Griffiths wrote: NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. That actually relates back to Craig Nelson hacking audio gear. He was really friendly and we had a nice chat about it. Read more here: http://tf.boulder.nist.gov/general/pdf/2556.pdf http://tf.boulder.nist.gov/general/pdf/2625.pdf http://www.nist.gov/customcf/get_pdf.cfm?pub_id=908622 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] GPSDO Component Selection
On Sun, Sep 9, 2012 at 1:14 PM, b...@lysator.liu.se wrote: True for a cheap oem navigation receiver. Not true for a geodetic quality receiver, who usually have some options (external frequency input, PPS_in) to make them the best timing receivers available. However they are much more expensive than the typical single frequency timing reciver. I looked at every link and can't see where they give a timing accuracy spec on the PPS with respect to UTC. Here is an older quote for geodetic quality time receivers. http://www.bipm.org/static/gpst/mail/13Jul99.1 Table 5. Inferred RMS day-boundary clock variations attributable to individual receivers === USNJ (Javad) 216 ps USNO (AOA TR)630 ps USNB (Ashtech) 574 ps === and some other links. http://tycho.usno.navy.mil/ptti/ptti2003/paper7.pdf http://tycho.usno.navy.mil/ptti/ptti2007/paper29.pdf https://goby.nrl.navy.mil/IGStime/index.php Possition accurracy is very good and we might assume the timing is as good. But they don't say it is. What's interesting is these GPSes will accept an accurate clock input in order to give better location data. That is the opposite of a timing GPS where you tell it accurate location data so that it can get better timing. You got it wrong, the external frequency input is primarily there to let you compare accurate clocks. There are few applications that really require an OCXO or better for position uses. Cutting down the unknown in one lets you do better in the other. I assume these all cost well over $50. That I said already... ;-) But then you will find a gem from time to time on the big epay river. -- Björn ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP10514B Mixer Terminations
Hi ….. and of course, once you go into saturation the mixer doesn't look much like 50 ohms any more. Sort of gets us back to terminations again. Bob On Sep 9, 2012, at 6:21 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. NIST used a simple diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst using a reactive termination for the difference frequency. With such a termination the minicircuits phase detectors had lower measured PN noise than the 10514. Another issue to consider is saturated or unsaturated (linear) operation of the mixer. Saturated operation, for most mixers, produces lower noise (flicker and floor) however linear operation can have for some mixers lower phase shift tempco which can be important depending on the environment and required phase shift stability. Bruce Bob Camp wrote: Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. 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. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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 Component Selection
On 09/09/2012 11:05 PM, Chris Albertson wrote: On Sun, Sep 9, 2012 at 1:14 PM,b...@lysator.liu.se wrote: True for a cheap oem navigation receiver. Not true for a geodetic quality receiver, who usually have some options (external frequency input, PPS_in) to make them the best timing receivers available. However they are much more expensive than the typical single frequency timing reciver. I looked at every link and can't see where they give a timing accuracy spec on the PPS with respect to UTC. Possition accurracy is very good and we might assume the timing is as good. But they don't say it is. What's interesting is these GPSes will accept an accurate clock input in order to give better location data. That is the opposite of a timing GPS where you tell it accurate location data so that it can get better timing. Cutting down the unknown in one lets you do better in the other. I assume these all cost well over $50. You can get a pretty good timing GPS for $30 and it WILL have the PPS error specified. To the OP. None of this matters a lot because PPS is a standard input signal. It is easy to swap out a GPS receiver later. Same with the OCXO. From a control point of view they are all pretty much the same. You can swap them out later There can be uncompensated delays, that always needs to be calibrated out. If you go looking around, you will find that they have gone through fair amount of effort to characterize the delay and it's temperature dependence among other things. Also, the PPS generation and it's precision isn't a good quality measure here, as the PPS is typically generated out of the internal clock and stepped in that clock. For the higher precision you need to use the data alongside it. For most of these, you do not provide external time but a better reference clock for a stable frequency, which will increase the quality of both time and position results. There are receivers in which you provide time as in 5/10 MHz and PPS, but then you get the time difference and position out of the receivers. So I agree with Björn here, but it may be beside the point unless you are eager to go over the steep step and into really good receivers. There even are rubidiums which learns of time and frequency errors out of GPS receiver messages. 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] GPSDO Component Selection
Hi Bob, Probably true for Motorola Oncores. Not very true for geodetic receivers. Until you have a receiver clock that is on par with the satellite clocks AND you are short on visable satellites. This might be true if you can load up a modern cesium in your vehicle, and go for a downtown urban valley type of scenario. On a stationary site, your expensive clock will not matter to much, since your solution is already pretty over-determined with some 60 measurements on each epoch. (9 GPS +6 Glonass)*2(L1/L2)*2 (code + phase) -- Björn Hi Position accuracy and timing accuracy are two very different things. Firmware is optimized to improve either one. Position firmware is often pretty poor for timing. Bob On Sep 9, 2012, at 5:05 PM, Chris Albertson albertson.ch...@gmail.com wrote: On Sun, Sep 9, 2012 at 1:14 PM, b...@lysator.liu.se wrote: True for a cheap oem navigation receiver. Not true for a geodetic quality receiver, who usually have some options (external frequency input, PPS_in) to make them the best timing receivers available. However they are much more expensive than the typical single frequency timing reciver. I looked at every link and can't see where they give a timing accuracy spec on the PPS with respect to UTC. Possition accurracy is very good and we might assume the timing is as good. But they don't say it is. What's interesting is these GPSes will accept an accurate clock input in order to give better location data. That is the opposite of a timing GPS where you tell it accurate location data so that it can get better timing. Cutting down the unknown in one lets you do better in the other. I assume these all cost well over $50. You can get a pretty good timing GPS for $30 and it WILL have the PPS error specified. To the OP. None of this matters a lot because PPS is a standard input signal. It is easy to swap out a GPS receiver later. Same with the OCXO. From a control point of view they are all pretty much the same. You can swap them out later Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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 Component Selection
Hi Indeed true for most non-geodetic gps units. Put another way - true unless you have a lot of money. Bob On Sep 9, 2012, at 7:25 PM, b...@lysator.liu.se wrote: Hi Bob, Probably true for Motorola Oncores. Not very true for geodetic receivers. Until you have a receiver clock that is on par with the satellite clocks AND you are short on visable satellites. This might be true if you can load up a modern cesium in your vehicle, and go for a downtown urban valley type of scenario. On a stationary site, your expensive clock will not matter to much, since your solution is already pretty over-determined with some 60 measurements on each epoch. (9 GPS +6 Glonass)*2(L1/L2)*2 (code + phase) -- Björn Hi Position accuracy and timing accuracy are two very different things. Firmware is optimized to improve either one. Position firmware is often pretty poor for timing. Bob On Sep 9, 2012, at 5:05 PM, Chris Albertson albertson.ch...@gmail.com wrote: On Sun, Sep 9, 2012 at 1:14 PM, b...@lysator.liu.se wrote: True for a cheap oem navigation receiver. Not true for a geodetic quality receiver, who usually have some options (external frequency input, PPS_in) to make them the best timing receivers available. However they are much more expensive than the typical single frequency timing reciver. I looked at every link and can't see where they give a timing accuracy spec on the PPS with respect to UTC. Possition accurracy is very good and we might assume the timing is as good. But they don't say it is. What's interesting is these GPSes will accept an accurate clock input in order to give better location data. That is the opposite of a timing GPS where you tell it accurate location data so that it can get better timing. Cutting down the unknown in one lets you do better in the other. I assume these all cost well over $50. You can get a pretty good timing GPS for $30 and it WILL have the PPS error specified. To the OP. None of this matters a lot because PPS is a standard input signal. It is easy to swap out a GPS receiver later. Same with the OCXO. From a control point of view they are all pretty much the same. You can swap them out later Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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 Component Selection
On 09/10/2012 01:28 AM, Bob Camp wrote: Hi Indeed true for most non-geodetic gps units. Put another way - true unless you have a lot of money. Well, you raise up from the normal noise just by adding carrier phase support and external clock. Can you do double frequency it's even better. Double freq and GPS + GLONASS is not what I can do right now... 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] GPSDO Component Selection
Hi Bob, This argument has been done before on time-nuts... sorry for repeating. There are geodetic quality GPS reveivers, like the Ashtech Z12-CORS (with external 5-20MHz input - not the true Z12 Metronome) available for a few hundred dollars occasionally. I got my Z12 CORS for free, from a site where it had been replaced by modern GPS/GLONASS receivers. I also found three Novatel Millenium OEM3 for ca $100 a piece, which in their days were used by national time labs. Unfortunately two of them has developed a problem with a custom IC. I am far from having the economic freedom to purchase a new H-Maser or Cesium. However I still have a HP5065A running in the basement. When new in the early 1970ties, you could probably have traded the rubidium for the house it is now running in. Conclusion: used geodetic gps equipment are no more expensive, than many of the oscillators we play with. They might actually once have been used in the same national time lab... ;-) -- Björn Hi Indeed true for most non-geodetic gps units. Put another way - true unless you have a lot of money. Bob On Sep 9, 2012, at 7:25 PM, b...@lysator.liu.se wrote: Hi Bob, Probably true for Motorola Oncores. Not very true for geodetic receivers. Until you have a receiver clock that is on par with the satellite clocks AND you are short on visable satellites. This might be true if you can load up a modern cesium in your vehicle, and go for a downtown urban valley type of scenario. On a stationary site, your expensive clock will not matter to much, since your solution is already pretty over-determined with some 60 measurements on each epoch. (9 GPS +6 Glonass)*2(L1/L2)*2 (code + phase) -- Björn Hi Position accuracy and timing accuracy are two very different things. Firmware is optimized to improve either one. Position firmware is often pretty poor for timing. Bob On Sep 9, 2012, at 5:05 PM, Chris Albertson albertson.ch...@gmail.com wrote: On Sun, Sep 9, 2012 at 1:14 PM, b...@lysator.liu.se wrote: True for a cheap oem navigation receiver. Not true for a geodetic quality receiver, who usually have some options (external frequency input, PPS_in) to make them the best timing receivers available. However they are much more expensive than the typical single frequency timing reciver. I looked at every link and can't see where they give a timing accuracy spec on the PPS with respect to UTC. Possition accurracy is very good and we might assume the timing is as good. But they don't say it is. What's interesting is these GPSes will accept an accurate clock input in order to give better location data. That is the opposite of a timing GPS where you tell it accurate location data so that it can get better timing. Cutting down the unknown in one lets you do better in the other. I assume these all cost well over $50. You can get a pretty good timing GPS for $30 and it WILL have the PPS error specified. To the OP. None of this matters a lot because PPS is a standard input signal. It is easy to swap out a GPS receiver later. Same with the OCXO. From a control point of view they are all pretty much the same. You can swap them out later Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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 Component Selection
Hi Except that on the same basis, the non-timing GPS gear is in the $10 to $20 range… Bob On Sep 9, 2012, at 7:55 PM, b...@lysator.liu.se wrote: Hi Bob, This argument has been done before on time-nuts... sorry for repeating. There are geodetic quality GPS reveivers, like the Ashtech Z12-CORS (with external 5-20MHz input - not the true Z12 Metronome) available for a few hundred dollars occasionally. I got my Z12 CORS for free, from a site where it had been replaced by modern GPS/GLONASS receivers. I also found three Novatel Millenium OEM3 for ca $100 a piece, which in their days were used by national time labs. Unfortunately two of them has developed a problem with a custom IC. I am far from having the economic freedom to purchase a new H-Maser or Cesium. However I still have a HP5065A running in the basement. When new in the early 1970ties, you could probably have traded the rubidium for the house it is now running in. Conclusion: used geodetic gps equipment are no more expensive, than many of the oscillators we play with. They might actually once have been used in the same national time lab... ;-) -- Björn Hi Indeed true for most non-geodetic gps units. Put another way - true unless you have a lot of money. Bob On Sep 9, 2012, at 7:25 PM, b...@lysator.liu.se wrote: Hi Bob, Probably true for Motorola Oncores. Not very true for geodetic receivers. Until you have a receiver clock that is on par with the satellite clocks AND you are short on visable satellites. This might be true if you can load up a modern cesium in your vehicle, and go for a downtown urban valley type of scenario. On a stationary site, your expensive clock will not matter to much, since your solution is already pretty over-determined with some 60 measurements on each epoch. (9 GPS +6 Glonass)*2(L1/L2)*2 (code + phase) -- Björn Hi Position accuracy and timing accuracy are two very different things. Firmware is optimized to improve either one. Position firmware is often pretty poor for timing. Bob On Sep 9, 2012, at 5:05 PM, Chris Albertson albertson.ch...@gmail.com wrote: On Sun, Sep 9, 2012 at 1:14 PM, b...@lysator.liu.se wrote: True for a cheap oem navigation receiver. Not true for a geodetic quality receiver, who usually have some options (external frequency input, PPS_in) to make them the best timing receivers available. However they are much more expensive than the typical single frequency timing reciver. I looked at every link and can't see where they give a timing accuracy spec on the PPS with respect to UTC. Possition accurracy is very good and we might assume the timing is as good. But they don't say it is. What's interesting is these GPSes will accept an accurate clock input in order to give better location data. That is the opposite of a timing GPS where you tell it accurate location data so that it can get better timing. Cutting down the unknown in one lets you do better in the other. I assume these all cost well over $50. You can get a pretty good timing GPS for $30 and it WILL have the PPS error specified. To the OP. None of this matters a lot because PPS is a standard input signal. It is easy to swap out a GPS receiver later. Same with the OCXO. From a control point of view they are all pretty much the same. You can swap them out later Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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 Component Selection
On 09/10/2012 02:14 AM, Bob Camp wrote: Hi Except that on the same basis, the non-timing GPS gear is in the $10 to $20 range… True, but better performance is reachable on a private budget. 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] HP10514B Mixer Terminations
What am I missing here? Vce = Vbe, so the diode connected transistor isn't saturated. -Original Message- From: Bob Camp li...@rtty.us Sender: time-nuts-boun...@febo.com Date: Sun, 9 Sep 2012 19:16:22 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] HP10514B Mixer Terminations Hi ….. and of course, once you go into saturation the mixer doesn't look much like 50 ohms any more. Sort of gets us back to terminations again. Bob On Sep 9, 2012, at 6:21 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. NIST used a simple diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst using a reactive termination for the difference frequency. With such a termination the minicircuits phase detectors had lower measured PN noise than the 10514. Another issue to consider is saturated or unsaturated (linear) operation of the mixer. Saturated operation, for most mixers, produces lower noise (flicker and floor) however linear operation can have for some mixers lower phase shift tempco which can be important depending on the environment and required phase shift stability. Bruce Bob Camp wrote: Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.com wrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. 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. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] HP10514B Mixer Terminations
Not transistor saturation but mixer saturation where the RF input is sufficiently that for a given LO level the IF output level is saturated (ie doesnt increase (or increases very slowly) with increasing RF signal level). Bruce li...@lazygranch.com wrote: What am I missing here? Vce = Vbe, so the diode connected transistor isn't saturated. -Original Message- From: Bob Campli...@rtty.us Sender: time-nuts-boun...@febo.com Date: Sun, 9 Sep 2012 19:16:22 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] HP10514B Mixer Terminations Hi ….. and of course, once you go into saturation the mixer doesn't look much like 50 ohms any more. Sort of gets us back to terminations again. Bob On Sep 9, 2012, at 6:21 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: NIST have indicated that mixer PN noise measurements with a non dissipative terminations (even RF) are intended to be made. Using a discrete mixer using diode connected transistors may also be useful at least for 5MHz and 10MHz input frequencies in that their flicker noise can be significantly lower than for mixers using diodes. NIST used a simple diplexer arrangement that terminates the RF sum frequency in 50 ohms whilst using a reactive termination for the difference frequency. With such a termination the minicircuits phase detectors had lower measured PN noise than the 10514. Another issue to consider is saturated or unsaturated (linear) operation of the mixer. Saturated operation, for most mixers, produces lower noise (flicker and floor) however linear operation can have for some mixers lower phase shift tempco which can be important depending on the environment and required phase shift stability. Bruce Bob Camp wrote: Hi In general, you terminate the mixer in 50 ohms at the RF frequencies (say 10 and 20 MHz). Termination at the IF (in this case audio) frequencies is what turns out to be tricky. Any time you terminate a source in a high impedance, you get a higher output voltage. Reactance rarely adds noise to a termination. With a DMTD, slew rate is the issue, generally mixer noise goes up less than the slew rate increases with a non-50 ohm termination. Bob On Sep 9, 2012, at 4:41 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: David Kirkby wrote: On 9 September 2012 18:28, Pascual Arbonap.arb...@securimar.comwrote: Hello Brian, I am a radio amateur and and also in the Time nuts list, At the moment I am planning to bild a DMTD for experimentation. and as you have a nice experience in this field , for me will be very wellcame your help. My ask is ¿whitch is te best temination for the mixer? (FI 10Hz or 100Hz) ¿what about the amp, limiters and zero crosing detec.) Mixers should be terminated in 50 Ohms - at least at all frequencies where there is an output. Someone mentioned minicircuits. They sell constant impedance filters, where the impedance in the both the passband and stopband are 50 Ohms. Most filters have a impedance far away from 50 Ohms in the stopband. This is an often repeated fallacy. For low IF frequencies such as in a DMTD, a reactive IF termination can have the advantage of lower noise and larger IF signal slew rate. The resultant reduction in RF and LO port VSWR is easily corrected (at least for low RF and LO frequencies) with a series resistor and/or resistive pad. There are a number of NIST papers on the effect of mixer termination for DMTDs and phase noise measurements. The minicircuits phase detectors (actually specialised mixers) are specified for use with 500 ohm IF terminations. I don't know the details of what you are trying to do, but keep in mind what I said. 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. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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
Re: [time-nuts] HP10514B Mixer Terminations
On 9/9/12 9:37 PM, li...@lazygranch.com wrote: What am I missing here? Vce = Vbe, so the diode connected transistor isn't saturated. I think it's where the diode is fully conducting, and into the linear part of the V/I curve, not in the square law part any more. In normal use the LO port is driven hard enough that the mixer is (hopefully) acting as a switch (and RF port is -10dB relative to the LO) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
