[time-nuts] TAPR TICC / PRS10

Bob kb8tq kb8tq at n1k.org
Thu Oct 4 22:19:05 EDT 2018


Hi

If you are doing a single device measurement *and* that device is also the reference,
the result will simply be the noise from the TICC. 

If you are doing an A / B comparison of two devices, both with 1 pps outputs, any error
from the GPSDO will scale with the time delta between the 1 pps arrival times. Simply put,
no big deal if they are within a few hundred nanoseconds of each other. 

At long offsets (say a half second) a 1 ppb error from the GPSDO will give you a half
nanosecond timing error on the comparison. That may or may not be significant, depending
on what else is going on.

If your GPSDO’s / standards  are running well, you will have a tough time measuring their actual ADEV
at short tau with a TICC. What you will be plotting is the noise floor of the TICC. That’s not a knock on 
the TICC, it does a good job for what it is. It simply can’t do everything ….

Bob



> On Oct 4, 2018, at 7:49 PM, Chris Burford <cburford1 at austin.rr.com> wrote:
> 
> Hello All,
> I'm very near purchasing a TICC unit to play with and to qualify my
> RFS and various GPSDO units. In reading the documentation for the TICC
> it requires a 10Mhz source input.
> Is (Are) there any issue(s) with using the 10MHz out on the RFS to the
> input reference on the TICC while simultaneously using the 1PPS out of
> the PRS for measurements? If need be I can use a GPSDO for the
> reference input to the TICC. I just thought it would make it easier on
> the RFS not having to be both the oscillator source and taking 1PPS at
> the same time from the RFS.
> I'm guessing that it is ok to source the RFS as the oscillator input
> and also measure the 1PPS simultaneously. I'd like to hear what
> potential "gotchas" may be lurking.
> Thanks for reading,Chris
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