Re: [time-nuts] FE-5680A Question
On Wed, 15 Feb 2012 12:03:45 -0800 Chris Albertson albertson.ch...@gmail.com wrote: It's like asking why did they change the design so that 5V is required, saves the cost of a regulator chip and some caps. They seem to be concerned with saving even $2 on a $1K device. It's a common misconception to think that the amount of money they try to safe per device is determined by the cost of the device while it actually is the number of devices produced. Saving $2 doesn't matter if you build just one device, no matter whether it costs $10 or $1000. The time you need to find those $2 costs you more than what you save. But if you build 100k devices, $2 will save you 200k. With that budget you can go on for a few months to find those $2 and still make money out of it. Attila Kinali -- Why does it take years to find the answers to the questions one should have asked long ago? ___ time-nuts mailing 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] FE-5680A Question
Hi The sweep range on the LPRO's is very similar to the sweep range on the FE's. They both run the VCXO over a very wide range compared to the width of the Rb resonance. They both also have to accommodate VCXO temperature performance and aging. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Wednesday, February 15, 2012 5:34 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] FE-5680A Question On Wed, Feb 15, 2012 at 2:17 PM, Bob Camp li...@rtty.us wrote: Hi If you look at an LPRO or FRS or any of the other brands of Rb's their sweep is very different. They don't spend very much time at the ends of the sweep at all. It's pretty much a triangle wave sweep up and back sort of thing. They don't seem to care weather they catch the lock going high to low or going low to high. The rate of the sweep is *much* slower than what FE is doing on these units. Since there isn't a brain in most of them, there's no pattern watching stuff there. They just look for a lock signal (amplitude out of the detector) and stop sweeping when they see it. That method requires that your sweep in so narrow that it can't catch any other adjacent spectral lines or dips in the light. FEI may have found a way to use a much wider sweep by havinf a brain able to know the fauslt dips from the one it wants. The ends that appear dead might be where the software analyses the data from the previous sweep. I doubt the little uP can mulitask. The uP is doing something when it is not sending commands to the DDS to cause the sweep. My understanding of a Rb physics package is that you get a forest of lines and only the one is the good one. 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] FE-5680A Question
Hi The sweep range on the LPRO is similar to the sweep range on the FE. The resonance on the FE may be wider than the LPRO. The cells are similar in size, so I would *guess* the Q's would be similar. The short term plots (good unit vs good unit) look a lot alike, which also would argue for a similar Q. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: Wednesday, February 15, 2012 5:37 PM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Question On 02/15/2012 11:17 PM, Bob Camp wrote: Hi If you look at an LPRO or FRS or any of the other brands of Rb's their sweep is very different. They don't spend very much time at the ends of the sweep at all. It's pretty much a triangle wave sweep up and back sort of thing. They don't seem to care weather they catch the lock going high to low or going low to high. The rate of the sweep is *much* slower than what FE is doing on these units. Since there isn't a brain in most of them, there's no pattern watching stuff there. They just look for a lock signal (amplitude out of the detector) and stop sweeping when they see it. Indeed. For analogue logics of the old dinsaurs that I hurd in the basement a sawtooth or triangle scanning is a good strategy to track in, but for a processor logic you can do things a bit differently. Also, consider that the Q seems to be wide on the FEI 5680A you can sweep faster without missing the dip. Another aspect on speed is just how large the (needed) scan range is. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FE-5680A Question
Hi Which still gets us back to - why the really odd sweep on the FE's? and should you center the VCXO as a matter of routine maintenance? Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: Tuesday, February 14, 2012 6:09 PM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Question On 02/14/2012 12:11 PM, Rex wrote: The Efrotoms (FRS-C. Lpro) find the lock by modulating the microwave frequency with an audio signal (127 Hz if I remember right) which causes the light sense modulated signal to double in frequency when centered on the hyperfine frequency. See the manuals for nice description. The 5680A seems to accomplish the same thing by stepping the frequency +/- 700 Hz rather than mixing in modulation. Never saw any documentation on that, but seems to be implied by the great hacking Javier Herrero has done on the loop frequencies. Seems to me that finding lock, that is finding the dip, may be a bit harder with the stepping than with the modulation. Maybe the observed drop in frequency during start up is part of the algorithm to walk the stepped frequency to center on the hyperfine light transmission dip. The modulation (may it be sine or square-wave) is about tracking the absorption dip. However, the initial frequency error of the OCXO can be so large that you don't even hit the dip at all. So, to achieve lock the non-locked state is detected by lack of response, and a sweeping action of the OCXO is done. If sufficient signal is detected, then the sweeping action is stopped and the loop is steered by the detected response which acts like a frequency locked loop. A little to much onto either side and a positive or negative response is given. When in the middle a maximum is achieved on the second harmonic. So, the initial large end-to-end sweeps is about to try to lock the OCXO onto the rubidium reference. That will fail until the OCXO has heated up enough and also the rubidium is heated enough. For some rubidiums you may need to hand-trim the oscillator in order to achieve lock, since their oscillators (crystals and tuning-cap) has wandered to far astray from locking-range. Rubidiums is a bit intricate, but the pieces fall together eventually. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FE-5680A Question
On Wed, Feb 15, 2012 at 9:12 AM, Bob Camp li...@rtty.us wrote: Hi Which still gets us back to - why the really odd sweep on the FE's? and should you center the VCXO as a matter of routine maintenance? I think a very asymmetric sweep makes the most sense. First some history of sailing ships. Back in the 1600's navigation was not perfect and you never knew your exact position on the open ocean. Knowing within 30 miles was hard to do. So to get to a given location in North America from Europe they typically would aim about 50 or more miles to the north of their intended destination and then when they reached land would sail south until they found the destination. This added a day or more to the trip. If they tried to hit the target dead-on they would likely miss but then they'd have to literally guess wetter to go North or South and if they guessed wrong it could really be bad so they always headed for enough north of the target so there was no guessing about which way to turn. I think the sweep is done the same way. If you start way low you know 100% which way to go, the lock has to be up. Seeing as we know they are using software in the loop this makes sense. So on pwr up the uP starts looking with bottom up sweeps. The sweeps fail to find lock because the temperatures of the crystal and Rb are to low but after some minutes, finally a sweep finds the lock 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] FE-5680A Question
Hi They do indeed need to know that they start low and go high. They do need to sweep to either side of the resonance. Every Rb I've ever torn into does those things. Why sweep *way* low, and almost not sweep high enough? Normally the sweep is centered. Why spend most of the sweep time not sweeping and then sweep real fast? I've never seen one that stops at the ends. Wouldn't it be better to spend the same time sweeping slowly? That's what the other designs all do. We're not going to do much about the dead time, but the centering of the sweep is something you will impact if you re-tune the VCXO. When you do retune it, it would be nice to know if the centering was dead on when manufactured and it's drifted, or if it needs to be off center in order to lock properly under all conditions. What could happen? There are multiple transitions in the Rb atom. Some of them are pretty close to the one we use. If you lock onto the wrong one, you are on the wrong frequency. Different designs get around the problem different ways. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Wednesday, February 15, 2012 12:36 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] FE-5680A Question On Wed, Feb 15, 2012 at 9:12 AM, Bob Camp li...@rtty.us wrote: Hi Which still gets us back to - why the really odd sweep on the FE's? and should you center the VCXO as a matter of routine maintenance? I think a very asymmetric sweep makes the most sense. First some history of sailing ships. Back in the 1600's navigation was not perfect and you never knew your exact position on the open ocean. Knowing within 30 miles was hard to do. So to get to a given location in North America from Europe they typically would aim about 50 or more miles to the north of their intended destination and then when they reached land would sail south until they found the destination. This added a day or more to the trip. If they tried to hit the target dead-on they would likely miss but then they'd have to literally guess wetter to go North or South and if they guessed wrong it could really be bad so they always headed for enough north of the target so there was no guessing about which way to turn. I think the sweep is done the same way. If you start way low you know 100% which way to go, the lock has to be up. Seeing as we know they are using software in the loop this makes sense. So on pwr up the uP starts looking with bottom up sweeps. The sweeps fail to find lock because the temperatures of the crystal and Rb are to low but after some minutes, finally a sweep finds the lock 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] FE-5680A Question
I can see the programmer writing code and he knows he has to wait for warm up. So he does a sweep then calls wait().Or it could be the software is doing more than one function and the dead time is used for measuring temperatures or currents, self tests or whatever. I think they do a wide bottom up sweep because they might be looking for landmarks, some dips that occur below the one they want. Possibly this is a cost saving thing. If you come up and are centered on exactly the dip you need you have t be accurate. But this one hunts by looking at nearby dips. We really can't know why it is designed this way and not some other way but I'd bet the reason is so they could use a cheaper less accurate crystal. It's like asking why did they change the design so that 5V is required, saves the cost of a regulator chip and some caps. They seem to be concerned with saving even $2 on a $1K device. On Wed, Feb 15, 2012 at 9:49 AM, Bob Camp li...@rtty.us wrote: Hi They do indeed need to know that they start low and go high. They do need to sweep to either side of the resonance. Every Rb I've ever torn into does those things. Why sweep *way* low, and almost not sweep high enough? Normally the sweep is centered. Why spend most of the sweep time not sweeping and then sweep real fast? I've never seen one that stops at the ends. Wouldn't it be better to spend the same time sweeping slowly? That's what the other designs all do. We're not going to do much about the dead time, but the centering of the sweep is something you will impact if you re-tune the VCXO. When you do retune it, it would be nice to know if the centering was dead on when manufactured and it's drifted, or if it needs to be off center in order to lock properly under all conditions. What could happen? There are multiple transitions in the Rb atom. Some of them are pretty close to the one we use. If you lock onto the wrong one, you are on the wrong frequency. Different designs get around the problem different ways. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Chris Albertson Sent: Wednesday, February 15, 2012 12:36 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] FE-5680A Question On Wed, Feb 15, 2012 at 9:12 AM, Bob Camp li...@rtty.us wrote: Hi Which still gets us back to - why the really odd sweep on the FE's? and should you center the VCXO as a matter of routine maintenance? I think a very asymmetric sweep makes the most sense. First some history of sailing ships. Back in the 1600's navigation was not perfect and you never knew your exact position on the open ocean. Knowing within 30 miles was hard to do. So to get to a given location in North America from Europe they typically would aim about 50 or more miles to the north of their intended destination and then when they reached land would sail south until they found the destination. This added a day or more to the trip. If they tried to hit the target dead-on they would likely miss but then they'd have to literally guess wetter to go North or South and if they guessed wrong it could really be bad so they always headed for enough north of the target so there was no guessing about which way to turn. I think the sweep is done the same way. If you start way low you know 100% which way to go, the lock has to be up. Seeing as we know they are using software in the loop this makes sense. So on pwr up the uP starts looking with bottom up sweeps. The sweeps fail to find lock because the temperatures of the crystal and Rb are to low but after some minutes, finally a sweep finds the lock 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. -- 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] FE-5680A Question
Hi Bob, On 02/15/2012 06:12 PM, Bob Camp wrote: Hi Which still gets us back to - why the really odd sweep on the FE's? They didn't look all that odd to me. As long as you do the sweeps every now and then you will lock up. I think you need to tell me what's so odd about them. and should you center the VCXO as a matter of routine maintenance? Yes, you should. It's fairly trivial as you just adjust it so the CV is mid-scale. If you do it regularly enough, every other year or so, getting back on track will never be a problem. Cheers, Magnus Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: Tuesday, February 14, 2012 6:09 PM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Question On 02/14/2012 12:11 PM, Rex wrote: The Efrotoms (FRS-C. Lpro) find the lock by modulating the microwave frequency with an audio signal (127 Hz if I remember right) which causes the light sense modulated signal to double in frequency when centered on the hyperfine frequency. See the manuals for nice description. The 5680A seems to accomplish the same thing by stepping the frequency +/- 700 Hz rather than mixing in modulation. Never saw any documentation on that, but seems to be implied by the great hacking Javier Herrero has done on the loop frequencies. Seems to me that finding lock, that is finding the dip, may be a bit harder with the stepping than with the modulation. Maybe the observed drop in frequency during start up is part of the algorithm to walk the stepped frequency to center on the hyperfine light transmission dip. The modulation (may it be sine or square-wave) is about tracking the absorption dip. However, the initial frequency error of the OCXO can be so large that you don't even hit the dip at all. So, to achieve lock the non-locked state is detected by lack of response, and a sweeping action of the OCXO is done. If sufficient signal is detected, then the sweeping action is stopped and the loop is steered by the detected response which acts like a frequency locked loop. A little to much onto either side and a positive or negative response is given. When in the middle a maximum is achieved on the second harmonic. So, the initial large end-to-end sweeps is about to try to lock the OCXO onto the rubidium reference. That will fail until the OCXO has heated up enough and also the rubidium is heated enough. For some rubidiums you may need to hand-trim the oscillator in order to achieve lock, since their oscillators (crystals and tuning-cap) has wandered to far astray from locking-range. Rubidiums is a bit intricate, but the pieces fall together eventually. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] FE-5680A Question
Hi If you look at an LPRO or FRS or any of the other brands of Rb's their sweep is very different. They don't spend very much time at the ends of the sweep at all. It's pretty much a triangle wave sweep up and back sort of thing. They don't seem to care weather they catch the lock going high to low or going low to high. The rate of the sweep is *much* slower than what FE is doing on these units. Since there isn't a brain in most of them, there's no pattern watching stuff there. They just look for a lock signal (amplitude out of the detector) and stop sweeping when they see it. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: Wednesday, February 15, 2012 3:34 PM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Question Hi Bob, On 02/15/2012 06:12 PM, Bob Camp wrote: Hi Which still gets us back to - why the really odd sweep on the FE's? They didn't look all that odd to me. As long as you do the sweeps every now and then you will lock up. I think you need to tell me what's so odd about them. and should you center the VCXO as a matter of routine maintenance? Yes, you should. It's fairly trivial as you just adjust it so the CV is mid-scale. If you do it regularly enough, every other year or so, getting back on track will never be a problem. Cheers, Magnus Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: Tuesday, February 14, 2012 6:09 PM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Question On 02/14/2012 12:11 PM, Rex wrote: The Efrotoms (FRS-C. Lpro) find the lock by modulating the microwave frequency with an audio signal (127 Hz if I remember right) which causes the light sense modulated signal to double in frequency when centered on the hyperfine frequency. See the manuals for nice description. The 5680A seems to accomplish the same thing by stepping the frequency +/- 700 Hz rather than mixing in modulation. Never saw any documentation on that, but seems to be implied by the great hacking Javier Herrero has done on the loop frequencies. Seems to me that finding lock, that is finding the dip, may be a bit harder with the stepping than with the modulation. Maybe the observed drop in frequency during start up is part of the algorithm to walk the stepped frequency to center on the hyperfine light transmission dip. The modulation (may it be sine or square-wave) is about tracking the absorption dip. However, the initial frequency error of the OCXO can be so large that you don't even hit the dip at all. So, to achieve lock the non-locked state is detected by lack of response, and a sweeping action of the OCXO is done. If sufficient signal is detected, then the sweeping action is stopped and the loop is steered by the detected response which acts like a frequency locked loop. A little to much onto either side and a positive or negative response is given. When in the middle a maximum is achieved on the second harmonic. So, the initial large end-to-end sweeps is about to try to lock the OCXO onto the rubidium reference. That will fail until the OCXO has heated up enough and also the rubidium is heated enough. For some rubidiums you may need to hand-trim the oscillator in order to achieve lock, since their oscillators (crystals and tuning-cap) has wandered to far astray from locking-range. Rubidiums is a bit intricate, but the pieces fall together eventually. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing 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] FE-5680A Question
On Wed, Feb 15, 2012 at 2:17 PM, Bob Camp li...@rtty.us wrote: Hi If you look at an LPRO or FRS or any of the other brands of Rb's their sweep is very different. They don't spend very much time at the ends of the sweep at all. It's pretty much a triangle wave sweep up and back sort of thing. They don't seem to care weather they catch the lock going high to low or going low to high. The rate of the sweep is *much* slower than what FE is doing on these units. Since there isn't a brain in most of them, there's no pattern watching stuff there. They just look for a lock signal (amplitude out of the detector) and stop sweeping when they see it. That method requires that your sweep in so narrow that it can't catch any other adjacent spectral lines or dips in the light. FEI may have found a way to use a much wider sweep by havinf a brain able to know the fauslt dips from the one it wants. The ends that appear dead might be where the software analyses the data from the previous sweep. I doubt the little uP can mulitask. The uP is doing something when it is not sending commands to the DDS to cause the sweep. My understanding of a Rb physics package is that you get a forest of lines and only the one is the good one. 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] FE-5680A Question
On 02/15/2012 11:17 PM, Bob Camp wrote: Hi If you look at an LPRO or FRS or any of the other brands of Rb's their sweep is very different. They don't spend very much time at the ends of the sweep at all. It's pretty much a triangle wave sweep up and back sort of thing. They don't seem to care weather they catch the lock going high to low or going low to high. The rate of the sweep is *much* slower than what FE is doing on these units. Since there isn't a brain in most of them, there's no pattern watching stuff there. They just look for a lock signal (amplitude out of the detector) and stop sweeping when they see it. Indeed. For analogue logics of the old dinsaurs that I hurd in the basement a sawtooth or triangle scanning is a good strategy to track in, but for a processor logic you can do things a bit differently. Also, consider that the Q seems to be wide on the FEI 5680A you can sweep faster without missing the dip. Another aspect on speed is just how large the (needed) scan range is. 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] FE-5680A Question
The Efrotoms (FRS-C. Lpro) find the lock by modulating the microwave frequency with an audio signal (127 Hz if I remember right) which causes the light sense modulated signal to double in frequency when centered on the hyperfine frequency. See the manuals for nice description. The 5680A seems to accomplish the same thing by stepping the frequency +/- 700 Hz rather than mixing in modulation. Never saw any documentation on that, but seems to be implied by the great hacking Javier Herrero has done on the loop frequencies. Seems to me that finding lock, that is finding the dip, may be a bit harder with the stepping than with the modulation. Maybe the observed drop in frequency during start up is part of the algorithm to walk the stepped frequency to center on the hyperfine light transmission dip. On 2/13/2012 4:39 PM, Bob Camp wrote: Hi If they are looking for a pattern what is the pattern? Bob On Feb 13, 2012, at 3:35 PM, paul swedpaulsw...@gmail.com wrote: The reason to sweep low is to establish a particular lock pattern to look for. Check the programmed offset before retuning. Mine was at mid range Search the threads for sending commands to the FE5680. On Mon, Feb 13, 2012 at 2:56 PM, Bob Campli...@rtty.us wrote: Hi For what ever reason, most of the FE's sweep down to about 200 to 250 Hz low. Few sweep more than 50 Hz high. I have one unit that locks fine and only sweeps 5 Hz high. Yes, I would open it up and re-tune. I think I would only bump it about 50 Hz or so. I have no idea *why* they are all tuned low, but there may be a reason (like avoiding a false lock). Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FE-5680A Question
Hi The interesting part is that the LPRO sweeps *much* slower than the FE. For what ever reason, the FE spends most of it's sweep cycle with the VCXO going nowhere (railed at one end or the other). Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Rex Sent: Tuesday, February 14, 2012 6:11 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] FE-5680A Question The Efrotoms (FRS-C. Lpro) find the lock by modulating the microwave frequency with an audio signal (127 Hz if I remember right) which causes the light sense modulated signal to double in frequency when centered on the hyperfine frequency. See the manuals for nice description. The 5680A seems to accomplish the same thing by stepping the frequency +/- 700 Hz rather than mixing in modulation. Never saw any documentation on that, but seems to be implied by the great hacking Javier Herrero has done on the loop frequencies. Seems to me that finding lock, that is finding the dip, may be a bit harder with the stepping than with the modulation. Maybe the observed drop in frequency during start up is part of the algorithm to walk the stepped frequency to center on the hyperfine light transmission dip. On 2/13/2012 4:39 PM, Bob Camp wrote: Hi If they are looking for a pattern what is the pattern? Bob On Feb 13, 2012, at 3:35 PM, paul swedpaulsw...@gmail.com wrote: The reason to sweep low is to establish a particular lock pattern to look for. Check the programmed offset before retuning. Mine was at mid range Search the threads for sending commands to the FE5680. On Mon, Feb 13, 2012 at 2:56 PM, Bob Campli...@rtty.us wrote: Hi For what ever reason, most of the FE's sweep down to about 200 to 250 Hz low. Few sweep more than 50 Hz high. I have one unit that locks fine and only sweeps 5 Hz high. Yes, I would open it up and re-tune. I think I would only bump it about 50 Hz or so. I have no idea *why* they are all tuned low, but there may be a reason (like avoiding a false lock). Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] FE-5680A Question
Hi Gents, received my FE-5680A UN 63401 S/N 0311-61144... Anybody can advise a few idea about this module..? From the label I can see it requires +5 Volt but no info about the RS232... Can I adjust the C field from the DB9 connector Any info appreciated. Many thanks and best regards, Ernie. ___ time-nuts mailing 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] FE-5680A Question
On Mon, 13 Feb 2012 08:29:43 -0500 (EST) Erno Peres erniepe...@aol.com wrote: received my FE-5680A UN 63401 S/N 0311-61144... Anybody can advise a few idea about this module..? From the label I can see it requires +5 Volt but no info about the RS232... Can I adjust the C field from the DB9 connector Any info appreciated. The info was given quite a few times on this mailinglis already. There is a faq available at [1] that covers all of your questions. For more information, read the mails with 5680 in the subject send on this ML from late December to now. You can find the link to the archive at the bottom of this mail. Attila Kinali [1] http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq -- The trouble with you, Shev, is you don't say anything until you've saved up a whole truckload of damned heavy brick arguments and then you dump them all out and never look at the bleeding body mangled beneath the heap -- Tirin, The Dispossessed, U. Le Guin ___ time-nuts mailing 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] FE-5680A Question
From the label I can see it requires +5 Volt but no info about the RS232... Can I adjust the C field from the DB9 connector On the units that require 5V you can adjust the frequency using rs-232 but only within a very small range around 10MHz. Some of the documentation applies to other types of this same model oscillator. 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] FE-5680A Question
Hi Chris, thanks for the info. My second problem is that the unit is in locked position after powering up but after about 5-8min the freq goes down slowly about 9.999.997.3 Hz and the lock ind level is still low. Also noticed that during the sweep the max freq is 10.000.004 Hz and the min freq is 9.999.750 Hz.. I assume that I have to open up the unit and try to re tune the 10Mhz sweep osci.. let say from 9.999.900 to 10.000.100 at least. Any suggestion Thanks and regards, Ernie. -Original Message- From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Mon, Feb 13, 2012 7:32 pm Subject: Re: [time-nuts] FE-5680A Question From the label I can see it requires +5 Volt but no info about the S232... Can I adjust the C field from the DB9 connector On the units that require 5V you can adjust the frequency using rs-232 ut only within a very small range around 10MHz. Some of the ocumentation applies to other types of this same model oscillator. Chris Albertson edondo Beach, California ___ ime-nuts mailing list -- time-nuts@febo.com o unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts nd 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] FE-5680A Question
Hi For what ever reason, most of the FE's sweep down to about 200 to 250 Hz low. Few sweep more than 50 Hz high. I have one unit that locks fine and only sweeps 5 Hz high. Yes, I would open it up and re-tune. I think I would only bump it about 50 Hz or so. I have no idea *why* they are all tuned low, but there may be a reason (like avoiding a false lock). Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Erno Peres Sent: Monday, February 13, 2012 2:17 PM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Question Hi Chris, thanks for the info. My second problem is that the unit is in locked position after powering up but after about 5-8min the freq goes down slowly about 9.999.997.3 Hz and the lock ind level is still low. Also noticed that during the sweep the max freq is 10.000.004 Hz and the min freq is 9.999.750 Hz.. I assume that I have to open up the unit and try to re tune the 10Mhz sweep osci.. let say from 9.999.900 to 10.000.100 at least. Any suggestion Thanks and regards, Ernie. -Original Message- From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Mon, Feb 13, 2012 7:32 pm Subject: Re: [time-nuts] FE-5680A Question From the label I can see it requires +5 Volt but no info about the S232... Can I adjust the C field from the DB9 connector On the units that require 5V you can adjust the frequency using rs-232 ut only within a very small range around 10MHz. Some of the ocumentation applies to other types of this same model oscillator. Chris Albertson edondo Beach, California ___ ime-nuts mailing list -- time-nuts@febo.com o unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts nd 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] FE-5680A Question
The reason to sweep low is to establish a particular lock pattern to look for. Check the programmed offset before retuning. Mine was at mid range Search the threads for sending commands to the FE5680. On Mon, Feb 13, 2012 at 2:56 PM, Bob Camp li...@rtty.us wrote: Hi For what ever reason, most of the FE's sweep down to about 200 to 250 Hz low. Few sweep more than 50 Hz high. I have one unit that locks fine and only sweeps 5 Hz high. Yes, I would open it up and re-tune. I think I would only bump it about 50 Hz or so. I have no idea *why* they are all tuned low, but there may be a reason (like avoiding a false lock). Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Erno Peres Sent: Monday, February 13, 2012 2:17 PM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Question Hi Chris, thanks for the info. My second problem is that the unit is in locked position after powering up but after about 5-8min the freq goes down slowly about 9.999.997.3 Hz and the lock ind level is still low. Also noticed that during the sweep the max freq is 10.000.004 Hz and the min freq is 9.999.750 Hz.. I assume that I have to open up the unit and try to re tune the 10Mhz sweep osci.. let say from 9.999.900 to 10.000.100 at least. Any suggestion Thanks and regards, Ernie. -Original Message- From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Mon, Feb 13, 2012 7:32 pm Subject: Re: [time-nuts] FE-5680A Question From the label I can see it requires +5 Volt but no info about the S232... Can I adjust the C field from the DB9 connector On the units that require 5V you can adjust the frequency using rs-232 ut only within a very small range around 10MHz. Some of the ocumentation applies to other types of this same model oscillator. Chris Albertson edondo Beach, California ___ ime-nuts mailing list -- time-nuts@febo.com o unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts nd 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] FE-5680A Question
Hi If they are looking for a pattern what is the pattern? Bob On Feb 13, 2012, at 3:35 PM, paul swed paulsw...@gmail.com wrote: The reason to sweep low is to establish a particular lock pattern to look for. Check the programmed offset before retuning. Mine was at mid range Search the threads for sending commands to the FE5680. On Mon, Feb 13, 2012 at 2:56 PM, Bob Camp li...@rtty.us wrote: Hi For what ever reason, most of the FE's sweep down to about 200 to 250 Hz low. Few sweep more than 50 Hz high. I have one unit that locks fine and only sweeps 5 Hz high. Yes, I would open it up and re-tune. I think I would only bump it about 50 Hz or so. I have no idea *why* they are all tuned low, but there may be a reason (like avoiding a false lock). Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Erno Peres Sent: Monday, February 13, 2012 2:17 PM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Question Hi Chris, thanks for the info. My second problem is that the unit is in locked position after powering up but after about 5-8min the freq goes down slowly about 9.999.997.3 Hz and the lock ind level is still low. Also noticed that during the sweep the max freq is 10.000.004 Hz and the min freq is 9.999.750 Hz.. I assume that I have to open up the unit and try to re tune the 10Mhz sweep osci.. let say from 9.999.900 to 10.000.100 at least. Any suggestion Thanks and regards, Ernie. -Original Message- From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Mon, Feb 13, 2012 7:32 pm Subject: Re: [time-nuts] FE-5680A Question From the label I can see it requires +5 Volt but no info about the S232... Can I adjust the C field from the DB9 connector On the units that require 5V you can adjust the frequency using rs-232 ut only within a very small range around 10MHz. Some of the ocumentation applies to other types of this same model oscillator. Chris Albertson edondo Beach, California ___ ime-nuts mailing list -- time-nuts@febo.com o unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts nd 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] FE-5680A Question
Hi Some numbers: C field tuning on a Rb like an FRS or an LPRO is about 2 to 6 ppb DDS tuning on the new FE's is in the 1 to 10 ppm range (1000x larger) DDS tuning on the old FE's was about 10% without mods, much wider with minor tuning. Bob On Feb 13, 2012, at 2:16 PM, Erno Peres erniepe...@aol.com wrote: Hi Chris, thanks for the info. My second problem is that the unit is in locked position after powering up but after about 5-8min the freq goes down slowly about 9.999.997.3 Hz and the lock ind level is still low. Also noticed that during the sweep the max freq is 10.000.004 Hz and the min freq is 9.999.750 Hz.. I assume that I have to open up the unit and try to re tune the 10Mhz sweep osci.. let say from 9.999.900 to 10.000.100 at least. Any suggestion Thanks and regards, Ernie. -Original Message- From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Mon, Feb 13, 2012 7:32 pm Subject: Re: [time-nuts] FE-5680A Question From the label I can see it requires +5 Volt but no info about the S232... Can I adjust the C field from the DB9 connector On the units that require 5V you can adjust the frequency using rs-232 ut only within a very small range around 10MHz. Some of the ocumentation applies to other types of this same model oscillator. Chris Albertson edondo Beach, California ___ ime-nuts mailing list -- time-nuts@febo.com o unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts nd 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] FE-5680A Question
The patterns simply the lead in to lock. Coming from a known position low in frequency... Nothing magical On Mon, Feb 13, 2012 at 7:48 PM, Bob Camp li...@rtty.us wrote: Hi Some numbers: C field tuning on a Rb like an FRS or an LPRO is about 2 to 6 ppb DDS tuning on the new FE's is in the 1 to 10 ppm range (1000x larger) DDS tuning on the old FE's was about 10% without mods, much wider with minor tuning. Bob On Feb 13, 2012, at 2:16 PM, Erno Peres erniepe...@aol.com wrote: Hi Chris, thanks for the info. My second problem is that the unit is in locked position after powering up but after about 5-8min the freq goes down slowly about 9.999.997.3 Hz and the lock ind level is still low. Also noticed that during the sweep the max freq is 10.000.004 Hz and the min freq is 9.999.750 Hz.. I assume that I have to open up the unit and try to re tune the 10Mhz sweep osci.. let say from 9.999.900 to 10.000.100 at least. Any suggestion Thanks and regards, Ernie. -Original Message- From: Chris Albertson albertson.ch...@gmail.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Mon, Feb 13, 2012 7:32 pm Subject: Re: [time-nuts] FE-5680A Question From the label I can see it requires +5 Volt but no info about the S232... Can I adjust the C field from the DB9 connector On the units that require 5V you can adjust the frequency using rs-232 ut only within a very small range around 10MHz. Some of the ocumentation applies to other types of this same model oscillator. Chris Albertson edondo Beach, California ___ ime-nuts mailing list -- time-nuts@febo.com o unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts nd 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.
