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 firmware dump
From: Chris Albertson albertson.ch...@gmail.com Email some of the sellers in China and offer to buy a returned unit. they must have some On Mon, Feb 13, 2012 at 5:55 PM, EB4APL eb4...@cembreros.jazztel.es wrote: I don't mind sending something like $5 to a buy group and we'll have enough with a few of us. But if I were Elio I'll not feel very happy using a working unit for this kind of use, This is the answer I got from 'nichegeek': We do would like to help but sorry that what we got from supplier is good items although it is secondhand products. I will buy one working unit just to be dissectioned. _Elio. ___ 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] Recommendation
I know this is off subject but I had such a good experience with rdr-electronics and they list items like Rb’s and GPS receivers. I bid and won a GPS receiver for my FE 5680A, but based on previous questions they noticed I had bid on the wrong one, they informed me and asked which one I wanted and let me change with out increase in cost. Super service! No wonder they have 100% rating. Bert Kehren ___ 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's suitability for use as a 10 MHz reference for microwave transverters
Nice job!! Rob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of C. Turner Sent: 13 February 2012 21:03 To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A's suitability for use as a 10 MHz reference for microwave transverters Last week I noted that the FE-5680A's barefoot output was found to NOT be a suitable 10 MHz reference for microwave transverters. Specifically, I tested it on two different 10 GHz transverters and found there to be objectionable levels of grunge on signals caused by low-level phase modulation internal to the '5680A and at 10 GHz the result of this phase modulation was a racket of audible and subaudible noises on CW carriers that made it difficult to find zero beat! In comparison, the 10 MHz outputs of the Z3801, Isotemp VCXO and LPRO-101 yielded results at 10 GHz that were quite clean. Related observations were also made by N8UR in his web page comparing various units. In order to clean up the output of the FE-5680A I did the obvious thing, disciplining a homebrew VCXO to its output - details are found here: http://www.ka7oei.com/10_MHz_Rubidium_FE-5680A.html While the comparison frequency is fairly high (1.25 MHz) the loop gain and bandwidth are quite low so it's pretty much the Butler oscillator VCXO that determines the phase noise of the 10 MHz output and I can't detect any audible artifacts from the '5680A at all. At the moment I don't have the means of generating a pristine test signal at 10368 MHz, but from what I can determine, the resulting CW notes from the transverter (being locked to the regenerated output of the the '5680A) compared to the other 10 MHz sources sound the same. At some point I hope to do a more-detailed analysis. Had I a low-noise canned 10 MHz VCXO around, I'd have probably used that rather than go through the hassle of building the oscillator, but none of the 10 MHz VCXOs that I *did* have on hand produced as good a CW note as the Butler built around a cheap microprocessor-type crystal. I also had on hand some 10 MHz ovenized VCXOs which would have worked fine, but not only were these too large to fit in the box, they would have added even more current consumption to an already power-hungry frequency source - an important consideration when operating from a battery! There are, no doubt, a number of ways one could do this same thing, but it's clear that this simple of a circuit will do an admirable job of extracting the frequency stability of the FE-5680A without the synthesis-related artifacts. Of course, the regenerated 10 MHz output will have a degree of variable phase offset with respect to the '5680A's barefoot 10 MHz output over varying conditions (such as temperature) but when used only as a frequency reference these rather slow changes are unimportant. 73, Clint KA7OEI ___ 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] Recommendation
I have also had great dealings with RDR. They are a great company to deal with. Thomas Knox From: ewkeh...@aol.com Date: Tue, 14 Feb 2012 07:28:11 -0500 To: time-nuts@febo.com Subject: [time-nuts] Recommendation I know this is off subject but I had such a good experience with rdr-electronics and they list items like Rb’s and GPS receivers. I bid and won a GPS receiver for my FE 5680A, but based on previous questions they noticed I had bid on the wrong one, they informed me and asked which one I wanted and let me change with out increase in cost. Super service! No wonder they have 100% rating. Bert Kehren ___ 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 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.
Re: [time-nuts] FE-5680A firmware dump
Elio, Let us contribute to the buy. If you can receive money by Paypal it wold be very easy. Best regards, Ignacio, EB4APL El 14/02/2012 13:26, Elio Corbolante escribió: From: Chris Albertsonalbertson.ch...@gmail.com Email some of the sellers in China and offer to buy a returned unit. they must have some On Mon, Feb 13, 2012 at 5:55 PM, EB4APLeb4...@cembreros.jazztel.es wrote: I don't mind sending something like $5 to a buy group and we'll have enough with a few of us. But if I were Elio I'll not feel very happy using a working unit for this kind of use, This is the answer I got from 'nichegeek': We do would like to help but sorry that what we got from supplier is good items although it is secondhand products. I will buy one working unit just to be dissectioned. _Elio. ___ 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 partial schematics (digital only)
At 09:24 PM 2/12/2012, Elio Corbolante wrote: Being not yet able to dump the FE-5680A firmware, I started to write down the DIGITAL part of the schematics: http://www.rhodiatoce.com/pics/time-nuts/FE-5680A/FE-5680A_schematics_v0.0.pdf I hope it can be useful to some of you. (any suggestion is welcome!) Nice work! I do have a defective non-locking FE-5680A, but the problems it has (incorrect serial command replies, way off DDS tuning values, and absence of 10 MHz once the microcontroller boots up) makes me think there's a problem with the CPLD or even the firmware in flash. I don't think it would be a good candidate for a firmware dump. -- newell N5TNL ___ 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 Schematics (v0.1)
at the following address: http://www.rhodiatoce.com/pics/time-nuts/FE-5680A/FE-5680A_schematics_v0.1.pdf you will find the 0.1 release of the FE-5680A schematics. New additions: - pinout of the unpopulated (24 pin) connector (J9) behind the DB9 - connections between CPU/MAX3232 and the *TWO* serial ports!!! - component values of the 10MHz filter + option on PCB to output a square 10MHz wave on DB9 - connections between CPU and MAX1246 (A/D converter) - connections between XC9572 and MAX392 (quad analog switch) - unknown pins marked as '?' As you can see, it seems FE-5680A fully supports 2 serial ports: one on DB9 and the other one on the unpopulated connector (J9) behind DB9. Any comments/suggestions are welcome. . ciao _Elio. ___ 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] LightSquared news
From today's telcom trade press: The FCC said late today that the International Bureau is proposing to vacate LightSquared, Inc.'s conditional authorization and indefinitely suspend its ancillary terrestrial component (ATC) authority in the wake of the National Telecommunications and Information Administration's recommendation that LightSquared's LTE (long term evolution) network can't operate as planned without causing harmful interference to government GPS (Global Positioning System) receivers. This is just a brief summary of a long article that has some nuances that are not represented here. The FCC intends to release a public notice tomorrow. It is not necessarily over, but it is looking better. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
