[time-nuts] phase lock
Mark C. Stephens
marks at non-stop.com.au
Sat Dec 24 04:50:29 EST 2011
Ah I have a pair of HP counters on my bench, one 5335 with known good performance and calibration and a 5370 with rather dubious performance history.. I have figured out how to do phase with the 5335 but the 5370 is still a bit of a mystery. The main problem seems to be finding and reserving a clear space on the workbench!
So I had a quick Google search and came up with a no nonsense example by Mr. W.J. Riley using something called a pictic and one of your 1992 counters. After reading that particular article have an idea of how to do it and the actual difficulties involved in getting precision measurement of pulse phase. It looks like months of interesting activity ;)
And I just realised you are the Chuck 'zmodem' Forsberg of Omen Tech. Our paths cross again, later after the BBS years. From 300 Baud to 57600 your zmodem was everything for me! I even used it as a terminal program! Good to see you are well, Chuck.
From: Chuck Forsberg WA7KGX N2469R [mailto:caf at omen.com]
Sent: Saturday, 24 December 2011 5:03 PM
To: Mark C. Stephens; time-nuts
Subject: Re: phase lock
I have a Racal-Dana 1992 Nanosecond Universal Counter that includes
a phase measuring function. I also have a GPIB interface and wrote some
C code to log these readings which can be displayed with gnuplot.
The phase should be measured for a very long time - days perhaps. The ability
to record the phase over that period is useful because the Thunderbolt will
have considerable (compared to the Rb) short term variance.
You could use a scope. If the X and Y channels can hack 10 MHz you can do a
Lissajous pattern. Otherwise display one and trigger on the other.
The frequency should be within a fraction of one Hz before worrying about the phase.
On 12/23/2011 03:32 PM, Mark C. Stephens wrote:
[cid:image001.gif at 01CCC276.1D67E7A0]
Hello Chuck, I noticed with interest you compared a thunderbolt to a RB standard using phase lock.
I wonder how you measured the phase lock?
My thoughts would be to use an Oscilloscope but do you have another method?
Many thanks, Mark
Mark C Stephens | Customer service engineer | Non-Stop Computer Ltd
* +61 2 9011 8186 | ( +61 428 256 334 | * marks at non-stop.com.au<mailto:marks at non-stop.com.au>
Non-Stop Computer PTY LTD
79 Devon St
Email: service at non-stop.com.au<mailto:service at non-stop.com.au>
Chuck Forsberg WA7KGX N2469R caf at omen.com<mailto:caf at omen.com> www.omen.com<http://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
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