[time-nuts] Fury Realhamradio listing
SAIDJACK at aol.com
SAIDJACK at aol.com
Sun Apr 29 16:11:16 EDT 2007
In a message dated 4/29/2007 04:13:30 Pacific Daylight Time,
cfmd at bredband.net writes:
>Indeed. Three-four transistors and a handfull of caps and resistors. The
>Z3801A uses the 10 MHz clock and thus require a x1000 interpolation, which
>easy enought to acheive. Look at the HP5335A service manual for further
>details. What you do is that you stretch the error-pulse (1-2 cycles) by
>charging a cap with one current and discharging it with another, the output
>then run into a comparator for the sake of gain. This stretched pulse is
>measured with the coarse clock and voila!
I respectfully disagree, if it was that easy to get 100ps accuracy and
resolution, then the 53132A would have it and not 150ps I would think.
Also, the PRS10 Stanford Rubiudium would have better than 1ns resolution for
time-tagging. I think they actually do resolve better than 1ns, but don't
On the Z3801A I am still seeing folks speculate that it has 100ps resolution
just because that's what they print out as the averaged value. Does anyone
have schematics to confirm this?
The user manual even states that the number is an averaged version of the
true Time Interval. Same for the 58503B.
There is an easy way to verify this for anyone with access to a Z3801A or
Both units use the VP Oncore, speced at 31ns RMS sawtooth 1PPS jitter and at
around 100ns peak to peak jitter.
So if the Time Intervall circuit was not doing any filtering (which we know
it does, since the HP manuals state that it does), then the Standard Deviation
of the PTIM:SYNC:TINT? query results should have a peak to peak result
slightly worse than 100ns, and a standard deviation of around 30ns. Of course we
would have to add the OCXO noise and the quantization error on top of these
Has anyone done any analysis on the TI values that the Z3801A gives (besides
GPSCon, which gives about 50ns pk to pk and 10+ns Standard Deviation for
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