[time-nuts] HP53132A vs SR625

[Bob Camp]

Hi

If the gate time is fairly long, the "notch" in the resolution is quite narrow. You don't have to be very far off of 10 MHz to go back to fairly high resolution. Again, not a knock on this fine counter, just something to watch out for. 

Bob

On Mar 17, 2013, at 7:45 AM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:

> On 03/17/2013 01:43 AM, Bob Camp wrote:
>> Hi
>> 
>> The 53132 is indeed a fine counter. It's got another flaw though - right at 10 MHz the resolution takes a dive. If you are doing time nut stuff, that may be a significant issue.
> 
> The frequency averaging method can make use of the beating of the reference clock against the incomming clock, to get more information on the frequency difference. If the clocks are near each other, it takes longer averaging to get the same effective resolution. You can expect the same type of effect around frequency ratios like 3/2 etc.
> 
> This is expected as it is a systematic effect where most of the new samples does not bring any new info as they pop in systematically in the places where they don't give info. Adding noise (sloppy trigger) could actually improve the precission, as it would combat the quantization effect.
> 
> Cheers,
> Magnus
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