Magnus, I went back to the shop tonight and checked both my FE-5680A's. Both pin 3 and pin 6 are 'high' when power is first applied. When the unit 'locks', both pin 3 and 6 go 'low' but pin 6 then puts out a 5 uSec wide 1 PPS pulse, as judged by my 'calibrated eyeball' which means that I used a stop watch and counted the time for 10 sweeps of my scope, triggered by pin 6 and set for 5 mSec/cm sweep. These are, indeed '1 pulse per second' pulses. Now, I need to move the power supplies, scope and FE-5680A to where my 5370B and TBolt are located. Don't hold your breath on that though, too many irons in the fire. Joe -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Magnus Danielson Sent: Wednesday, January 25, 2012 1:19 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Determination of the placement of the first pps Hi Joe, On 01/25/2012 08:04 PM, J. L. Trantham wrote: > Magnus, > > Thanks for the research. Now that I have read your information, I am going > to have to go back and 'measure' the PPS output on my unit. I just > 'eyeballed' the '1 PPS' and it seemed close to 1 second. Good luck. Hopefully I put you onto a working solution. > It would be nice to find a serial command that would allow placing the 1 PPS > at any arbitrary point in phase to match GPS. > > My impression of reading the posts about the FE-5680A is that the 1 PPS is > likely there, just not easily documented. Well, being lazy enough not to go into the lab and open up my 5680 I went hunting the web and it seems like there was more out there than we seems to have been piecing together. Seems like a bit of more systematic research needs to be done. There are obviously at least two basic models, one older with 50,255+ MHz oscillators and various add-on boards and secondly the 60 MHz + DDS variant. Reverse-engineering the schematics and functions has only partly been done, but I haven't seen any systematic schematic popping out of the work. There is already plenty of information available, but it is not coordinated and systematically done to the level that most aspects can be written down in a service type of document. 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.

     mean: 999.999 900 993 ms
     sdev: 253 ps
     min : 999.999 900 49 ms
     max : 999.999 901 68 ms
     evnt: 100

     mean: 1.000 000 099 83 Hz
     sdev: 289 pHz (?)
     min : 1.000 000 099 04 Hz
     max : 1.000 000 100 62 Hz
     evnt: 100

At 09:13 PM 1/25/2012, J. L. Trantham wrote: >Both pin 3 and pin 6 are 'high' when power is first applied. When the unit >'locks', both pin 3 and 6 go 'low' but pin 6 then puts out a 5 uSec wide 1 >PPS pulse, as judged by my 'calibrated eyeball' which means that I used a >stop watch and counted the time for 10 sweeps of my scope, triggered by pin >6 and set for 5 mSec/cm sweep. These are, indeed '1 pulse per second' >pulses. I attempted to test a FE-5680A pps against the tbolt. I had the 10 MHz tbolt out to my (somewhat flaky) 5370A's ref in. Here's what I got for 100 events, which took about 3:20 to complete: mean: 999.999 900 993 ms sdev: 253 ps min : 999.999 900 49 ms max : 999.999 901 68 ms evnt: 100 Now this was a few days ago and I was confused so don't put too much trust in these numbers. FYI, the tbolt pps output measured as (not freq, not period): mean: 1.000 000 099 83 Hz sdev: 289 pHz (?) min : 1.000 000 099 04 Hz max : 1.000 000 100 62 Hz evnt: 100 -- newell N5TNL