[time-nuts] DMTD to MMTD

Bruce Griffiths bruce.griffiths at xtra.co.nz
Wed Feb 17 22:26:46 UTC 2010


Lux, Jim (337C) wrote:
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob Camp
>> Sent: Wednesday, February 17, 2010 1:57 PM
>> To: 'Discussion of precise time and frequency measurement'
>> Subject: Re: [time-nuts] DMTD to MMTD
>>
>> Hi
>>
>> Thanks for the quick response.
>>
>> The impression I've always had of that system is that it is comparing the
>> sources two at a time. They can select between a number of sources, but only
>> one pair is looked at.
>>
>>      
> It basically timestamps transitions on all 8 inputs.  The post processing software that looks a the timestamps is what selects either 1 channel (single mixer+offset generator) or 2 channels (dual mixer time difference)
>
> The counters in the FPGA are running at 100 MHz, so they have a basic resolution of 10 ns.
>
> _______________________________________________
>    
See:

http://tycho.usno.navy.mil/ptti/ptti2006/paper11.pdf


Bruce





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