[time-nuts] TIC Characterization

[Magnus Danielson]

Hi Poul-Henning,

On 12/30/18 2:15 PM, Poul-Henning Kamp wrote:
> --------
> In message <e2141e96-9c20-02f0-3225-e228b56763f6 at rubidium.dyndns.org>, Magnus D
> anielson writes:
>> Hi Gilles,
>>
>> On 12/29/18 11:28 PM, Club-Internet Clemgill wrote:
>>> Hi, 
>>> Looking to testing my HP53132A in TIC mode. 
>>> I considered the Time Interval measurement technique: 
>>> The start channel is connected to a 1 PPS signal, and to the stop channel though a coax cable (constant delay line).
>>
>> Fair enough setup. This is a static test setup which works as long as
>> you do not lock the counter up to a 10 MHz of the same source as the
>> PPS, and for all maters not accurate enough, so it's best for the test
>> for it to be free-running.
> 
> Here is another test-setup, which is very revealing about non-white
> noise in TIC counters:
> 
> You need a signal generator which can be locked to an external
> frequency and control the phase of the output signal relative to
> that external frequency.  The HP3336 is a good cancidate.
> 
> Lock both the counter under investigation and the siggen to the
> same house standard.  Set the siggen to output same frequency as
> house standard.
> 
> measure (start=house_std, stop=siggen) and (start=siggen, stop=house_std) for
> as many siggen phase settings as you have patience for.
> 
> Plot results, and wonder why you don't get a straight line...
> 

Well, this was the second setup I was talking about. To disclose the
full non-linearity you want to tweak it to 9.999 MHz rather than 10 MHz.
That will sweep through lots of phase relationships between the
time-base input and the TIC input. That would sweep the states with 10
ps for each cycle and thus be quite revealing. If you measured long
enough you would relatively well sampled all the phase relationships and
can now see how that looks as an average curve.

Cheers,
Magnus