[time-nuts] Entry Level Systems Revisited
I've been researching an entry-level system for my own learning and experimentation. Back in May of 2006 there was a thread that posed the question What's a good entry-level time reference system?. At that time there were several options suggested (partial list): - A local frequency standard (HP 10811A, HP10544A, Efratom Rubidium Standard) - A frequency/time interval counter (HP 5334A/B, HP 5345A, HP 5335A with high-stability options, HPIB nice to have, 1.3 Ghz options nice to have) - GPS or other radio reference (Morotola M12+T or UT+ , Garmin GPS-18 LVC) - GPS to NTP converter if doing NTP After a bit more searching in the archives I also ran across the Trimble Thunderbolt (and newer Thunderbolt E). I'm thinking of the following: - Skip the local frequency standard and opt for a high-stability counter - Trimble Thunderbolt or another GPS option - Nice clock that I can drive with 1 PPS (suggestions please) I would be very interested to see what type of entry-level system suggestions there are after the question was first posed a year and a half ago. //MDYER ___ time-nuts mailing 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] Entry Level Systems Revisited
Hi Michael, Well, entry level to me means the least expensive way to have a house standard. So I doubt the basic premises have changed much. Depending upon one's means, a high stability fancy counter may not be in the offering. Therefore, some decent (hopefully cheap) oscillator locked to the GPS provides the basics allowing for very inexpensive counters and other inexpensive devices to provide a degree of comfort. BillWB6BNQ Michael J. Dyer wrote: I've been researching an entry-level system for my own learning and experimentation. Back in May of 2006 there was a thread that posed the question What's a good entry-level time reference system?. At that time there were several options suggested (partial list): - A local frequency standard (HP 10811A, HP10544A, Efratom Rubidium Standard) - A frequency/time interval counter (HP 5334A/B, HP 5345A, HP 5335A with high-stability options, HPIB nice to have, 1.3 Ghz options nice to have) - GPS or other radio reference (Morotola M12+T or UT+ , Garmin GPS-18 LVC) - GPS to NTP converter if doing NTP After a bit more searching in the archives I also ran across the Trimble Thunderbolt (and newer Thunderbolt E). I'm thinking of the following: - Skip the local frequency standard and opt for a high-stability counter - Trimble Thunderbolt or another GPS option - Nice clock that I can drive with 1 PPS (suggestions please) I would be very interested to see what type of entry-level system suggestions there are after the question was first posed a year and a half ago. //MDYER ___ time-nuts mailing 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] Entry level systems
John, What do you do with the time interval function? I have an Advantest (actually Takeda Riken) TR 5823H counter that has time interval functionality with 0.1nS resolution. How can I use that to sync an HP 10811-60102 VOCXO to a Jupiter GPS receiver? The TakedaRiken manual is pretty useless, but it seems to say the minimum time interval that can be measured is 50nS, even though it has 0.1nS resolution. It does not have GPIB. This model had a D/A output option, but my unit does not have it. Thanks Didier KO4BB John Ackermann N8UR wrote: Keith E. Brandt, M.D. said the following on 05/24/2006 06:06 PM: What's a good entry-level time reference system? Interesting question! Assuming you mainly want to have a test-bed for learning and experimentation, I'd say you want three things: 1) a local frequency standard, 2) a frequency/time interval counter, and 3) a GPS or other radio reference. ... Hope this helps. 73, John ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Entry level systems
I use time interval to compare frequency offset and stability by feeding the unknown signal into the start input, and the reference into the stop input. The actual time interval doesn't matter, but by tracking the delta in time interval you can determine offset and drift. Typically, you use 1pps to do this, but there are ways to use higher frequencies, though they run into problems with cycle slip if the two sources aren't very close to each other. John Didier Juges said the following on 05/27/2006 12:23 PM: John, What do you do with the time interval function? I have an Advantest (actually Takeda Riken) TR 5823H counter that has time interval functionality with 0.1nS resolution. How can I use that to sync an HP 10811-60102 VOCXO to a Jupiter GPS receiver? The TakedaRiken manual is pretty useless, but it seems to say the minimum time interval that can be measured is 50nS, even though it has 0.1nS resolution. It does not have GPIB. This model had a D/A output option, but my unit does not have it. Thanks Didier KO4BB John Ackermann N8UR wrote: Keith E. Brandt, M.D. said the following on 05/24/2006 06:06 PM: What's a good entry-level time reference system? Interesting question! Assuming you mainly want to have a test-bed for learning and experimentation, I'd say you want three things: 1) a local frequency standard, 2) a frequency/time interval counter, and 3) a GPS or other radio reference. ... Hope this helps. 73, John ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Entry level systems
Thanks John, That makes sense. I tried feeding the 10 MHz of two HP synthesizers and got useless results. Now I see why. I understand that using the 1 pps output makes more sense. If my counter had the a/d output, I would be very close to having all I need to synchronize the VCXO to GPS... Didier KO4BB John Ackermann N8UR wrote: I use time interval to compare frequency offset and stability by feeding the unknown signal into the start input, and the reference into the stop input. The actual time interval doesn't matter, but by tracking the delta in time interval you can determine offset and drift. Typically, you use 1pps to do this, but there are ways to use higher frequencies, though they run into problems with cycle slip if the two sources aren't very close to each other. John ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
[time-nuts] Entry level systems
What's a good entry-level time reference system? I'm doing this for the fun/learning/hobby and can't dump $10k into it (without also incurring the attendant lawyer's fee for the divorce settlement :-) I think something along the lines of the TAPR TAC would be perfect if they still made it. Are there other relatively low-cost GPS reference systems out there? Keith LtCol Keith E. Brandt, MD, MPH USAF-NASA Aerospace Medicine Liaison Officer Johnson Space Center, Houston, Texas [EMAIL PROTECTED] Goodbye cruel world that was my home- there's cleaner space out here to roam Put my feet up on the moons of Mars- sit back, relax, and count the stars *This message transmitted with 100% recycled electrons ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Entry level systems
Hi Keith: A lot depends on what you're trying to do. Do you already have a counter that will make time interval measurements and if so with a lot of averaging what's the smallest time interval you can see? Do you already have frequency standard(s) and just want to use GPS to check on them or discipline them? The features of the TAC may or may not be a good fit to your needs. Can you elaborate on your goals / interests / etc.? Have Fun, Brooke Clarke -- w/Java http://www.PRC68.com w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml http://www.precisionclock.com Keith E. Brandt, M.D. wrote: What's a good entry-level time reference system? I'm doing this for the fun/learning/hobby and can't dump $10k into it (without also incurring the attendant lawyer's fee for the divorce settlement :-) I think something along the lines of the TAPR TAC would be perfect if they still made it. Are there other relatively low-cost GPS reference systems out there? Keith LtCol Keith E. Brandt, MD, MPH USAF-NASA Aerospace Medicine Liaison Officer Johnson Space Center, Houston, Texas [EMAIL PROTECTED] Goodbye cruel world that was my home- there's cleaner space out here to roam Put my feet up on the moons of Mars- sit back, relax, and count the stars *This message transmitted with 100% recycled electrons ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Entry level systems
Keith E. Brandt, M.D. said the following on 05/24/2006 06:06 PM: What's a good entry-level time reference system? I'm doing this for the fun/learning/hobby and can't dump $10k into it (without also incurring the attendant lawyer's fee for the divorce settlement :-) I think something along the lines of the TAPR TAC would be perfect if they still made it. Are there other relatively low-cost GPS reference systems out there? Interesting question! Assuming you mainly want to have a test-bed for learning and experimentation, I'd say you want three things: 1) a local frequency standard, 2) a frequency/time interval counter, and 3) a GPS or other radio reference. For the frequency standard, one of the surplus HP 10811A or 10544A oven crystal oscillators (OCXO) which can be had on eBay for $50 - $150 would be good, or one of the surplus Efratom Rubidium standards that go for the $250 range -- each has its own advantages; the crystal will have better short term stability and less phase noise, but the Rb will have better long term stability and will need to be recalibrated far less often. For the frequency counter/time interval counter, I am very partial to the HP 5334A or B. They are quite cheap on eBay (usually less than $150 and have 2ns time interval resolution. As a bonus, many of them have the high-stability option (001) that includes an HP 10811A oscillator, and if you find one with the channel C option you will be able to read frequency to 1.3GHz. Finally for the GPS. We're in a state of flux right now because Motorola sold their line of GPS receivers and the one everyone would have recommended last year is no longer available. Nonetheless, you may be able to find an M12+T receiver which is the best unit they had available, or the slightly older UT+. You'll need an antenna, but you don't necessarily need the TAC-2 -- all it really does is provide power supply and I/O buffering. You can do that on a piece of perfboard if you want. There are lots of other neat toys, but with those three you'll have a good frequency standard and a way to calibrate it. Hope this helps. 73, John ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Entry level systems
Hi Keith: A lot depends on what you're trying to do. Do you already have a counter that will make time interval measurements and if so with a lot of averaging what's the smallest time interval you can see? Do you already have frequency standard(s) and just want to use GPS to check on them or discipline them? The features of the TAC may or may not be a good fit to your needs. Can you elaborate on your goals / interests / etc.? Have Fun, Brooke Clarke Thanks for the reply. I am starting from essentially nothing. The most practical use I would have is a primary source for NTP. Other than that, it would be experimenting with setting up an accurate time source. LtCol Keith E. Brandt, MD, MPH USAF-NASA Aerospace Medicine Liaison Officer Johnson Space Center, Houston, Texas [EMAIL PROTECTED] Goodbye cruel world that was my home- there's cleaner space out here to roam Put my feet up on the moons of Mars- sit back, relax, and count the stars *This message transmitted with 100% recycled electrons ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Entry level systems
Keith E. Brandt, M.D. wrote: Thanks for the reply. I am starting from essentially nothing. The most practical use I would have is a primary source for NTP. Other than that, it would be experimenting with setting up an accurate time source. You can forgo the local freq. std. if your just want to run an NTP server. They're great to have, but can be added later. Most GPS's with a serial connection will work well enough for many applications. The Motorola OnCores are supposed to be quite good. I'd like to say I've got mine up and running, but the truth is that I've spent the past week dealing with the disaster of a fish pond in my back yard. cheers, glenn ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Entry level systems
I am starting from essentially nothing. The most practical use I would have is a primary source for NTP. Other than that, it would be experimenting with setting up an accurate time source. If you want to start with NTP, the Garmin GPS-18 LVC is popular. It's a hockey puck. Mine is inside. It works most of the time. You need the LVC version. The others don't have the PPS output. Some assembly required. One trick is to steal power from USB. Total cost should be under $100. (Assuminng you already have a soldering iron and such.) Lots of good info at: http://ntp.isc.org/bin/view/Main/WebHome Refclock info at: http://ntp.isc.org/bin/view/Support/ConfiguringRefclocks -- The suespammers.org mail server is located in California. So are all my other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited commercial e-mail to my suespammers.org address or any of my other addresses. These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Entry level systems
[EMAIL PROTECTED] said the following on 05/24/2006 08:23 PM: Hello John, I have several HP 5334's (A and B), and there is a trick how you can get from 2ns (2E-09) resolution to 10ps (1E-11) on these great units. To measure a 10MHz reference at 100micro Hertz resolution: * Do an offset of 10MHz (subtract 10MHz from your reading) * then set the gate time to its maximum of 99 seconds. Voila, the unit now displays the difference between it's internal OCXO to your source in 0.0001Hz resolution. Very clever trick! Thanks much, Said. John ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Entry level systems
At 06:31 PM 5/24/2006, John Ackermann N8UR wrote: Keith E. Brandt, M.D. said the following on 05/24/2006 06:06 PM: What's a good entry-level time reference system? I'm doing this for the fun/learning/hobby and can't dump $10k into it (without also incurring the attendant lawyer's fee for the divorce settlement :-) I think something along the lines of the TAPR TAC would be perfect if they still made it. Are there other relatively low-cost GPS reference systems out there? Interesting question! Assuming you mainly want to have a test-bed for learning and experimentation, I'd say you want three things: 1) a local frequency standard, 2) a frequency/time interval counter, and 3) a GPS or other radio reference. For the frequency standard, one of the surplus HP 10811A or 10544A oven crystal oscillators (OCXO) which can be had on eBay for $50 - $150 would be good, or one of the surplus Efratom Rubidium standards that go for the $250 range -- each has its own advantages; the crystal will have better short term stability and less phase noise, but the Rb will have better long term stability and will need to be recalibrated far less often. You will often find that it is cheaper to buy a counter with the high-stab oven option than to buy the oven separately. For the frequency counter/time interval counter, I am very partial to the HP 5334A or B. They are quite cheap on eBay (usually less than $150 and have 2ns time interval resolution. As a bonus, many of them have the high-stability option (001) that includes an HP 10811A oscillator, and if you find one with the channel C option you will be able to read frequency to 1.3GHz. The 5335A is also sold from about $100 up and has the oven option as opt010, 1.3GHz is opt030 and opt040 - expanded HPIB control is worth having if you plan to remote the counter at all. A little heavier is the 5345A which can be equipped for operation all the way to 40GHz or so at not a huge expense. It is one of my all time favourites. It has 2ns resolution and counts direct to 500MHz. They came as standard with the high stab oven, opt001 removes the oven. Opt010 is very basic HPIB talk only, opt011 HPIB with remote programming, opt012 is HPIB like 011 but has control of slope and trigger level as well. You can pay from $80 or so for basic counter with HPIB. Just get the seller to confirm it is not Opt 001! The 5345 is heavy, and a bit noisier than the newer 5334A/B or 5335A. To my m ind if you are interested in frequerncy measurement, this counter can give you flexibility well beyond anything else that mere mortals can afford when coupled with various plug-ins and convertor heads. 73's, John (ex VK3ZJF) Finally for the GPS. We're in a state of flux right now because Motorola sold their line of GPS receivers and the one everyone would have recommended last year is no longer available. Nonetheless, you may be able to find an M12+T receiver which is the best unit they had available, or the slightly older UT+. You'll need an antenna, but you don't necessarily need the TAC-2 -- all it really does is provide power supply and I/O buffering. You can do that on a piece of perfboard if you want. There are lots of other neat toys, but with those three you'll have a good frequency standard and a way to calibrate it. Hope this helps. 73, John ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
Re: [time-nuts] Entry level systems HP 5345
Hi John: I'm using the HP 5345A opt 11 now and really like it. When in the Time Interval mode (cesium s/n 1227 1 MHz on start and cesium s/n 1013 1 MHz on stop) you can turn the Gate Time knob up from MIN to say 1 SEC. What this does is to accumulate the gate times for as many receptive measurements as it takes to get to a total of 1 second, so the number of measurements depends on the actual TI being measured. For example with 1 SEC gate time and a TI of about 574 ns it takes about 3 seconds of clock time per measurement. The display is like 574.419,441 nano seconds. That's 574 nano seconds and 419 pico seconds and 441 femto seconds. If you set the gate time longer you get more digits. So at 10 SEC you get 0.1 femto seconds resolution after a 30 second wait. Simply fantastic! It counts to 500 MHz without any plugins unlike the HP 5245 that needs a plugin to get to 500 MHz. But a drawback to the early models is that the air filter is buried behind the FRONT panel and needs servicing something like twice a year. This required taking the counter apart. In later versions they removed the air filter. Although I can read HP-IB data in talk only mode, I haven't figured out the secret of two way communication. But the SR620 is still hands down my favorite TI counter. 16 digits with a fixed weight on the positions is a really good layout. Have Fun, Brooke Clarke John Day wrote: At 06:31 PM 5/24/2006, John Ackermann N8UR wrote: Keith E. Brandt, M.D. said the following on 05/24/2006 06:06 PM: What's a good entry-level time reference system? I'm doing this for the fun/learning/hobby and can't dump $10k into it (without also incurring the attendant lawyer's fee for the divorce settlement :-) I think something along the lines of the TAPR TAC would be perfect if they still made it. Are there other relatively low-cost GPS reference systems out there? Interesting question! Assuming you mainly want to have a test-bed for learning and experimentation, I'd say you want three things: 1) a local frequency standard, 2) a frequency/time interval counter, and 3) a GPS or other radio reference. For the frequency standard, one of the surplus HP 10811A or 10544A oven crystal oscillators (OCXO) which can be had on eBay for $50 - $150 would be good, or one of the surplus Efratom Rubidium standards that go for the $250 range -- each has its own advantages; the crystal will have better short term stability and less phase noise, but the Rb will have better long term stability and will need to be recalibrated far less often. You will often find that it is cheaper to buy a counter with the high-stab oven option than to buy the oven separately. For the frequency counter/time interval counter, I am very partial to the HP 5334A or B. They are quite cheap on eBay (usually less than $150 and have 2ns time interval resolution. As a bonus, many of them have the high-stability option (001) that includes an HP 10811A oscillator, and if you find one with the channel C option you will be able to read frequency to 1.3GHz. The 5335A is also sold from about $100 up and has the oven option as opt010, 1.3GHz is opt030 and opt040 - expanded HPIB control is worth having if you plan to remote the counter at all. A little heavier is the 5345A which can be equipped for operation all the way to 40GHz or so at not a huge expense. It is one of my all time favourites. It has 2ns resolution and counts direct to 500MHz. They came as standard with the high stab oven, opt001 removes the oven. Opt010 is very basic HPIB talk only, opt011 HPIB with remote programming, opt012 is HPIB like 011 but has control of slope and trigger level as well. You can pay from $80 or so for basic counter with HPIB. Just get the seller to confirm it is not Opt 001! The 5345 is heavy, and a bit noisier than the newer 5334A/B or 5335A. To my m ind if you are interested in frequerncy measurement, this counter can give you flexibility well beyond anything else that mere mortals can afford when coupled with various plug-ins and convertor heads. 73's, John (ex VK3ZJF) Finally for the GPS. We're in a state of flux right now because Motorola sold their line of GPS receivers and the one everyone would have recommended last year is no longer available. Nonetheless, you may be able to find an M12+T receiver which is the best unit they had available, or the slightly older UT+. You'll need an antenna, but you don't necessarily need the TAC-2 -- all it really does is provide power supply and I/O buffering. You can do that on a piece of perfboard if you want. There are lots of other neat toys, but with those three you'll have a good frequency standard and a way to calibrate it. Hope this helps. 73, John ___ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
