[time-nuts] Delay through GPS antenna splitter/amplifier -- an answer, and a question

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon Mar 12 18:39:12 EDT 2007


Tim Shoppa wrote:
> John Ackermann N8UR <jra at febo.com> wrote:
>   
>> But we're time-nuts... we DO worry about those things. :-)
>>
>> While we were at it with the network analyzer, we did FDR (frequency 
>> domain reflectometry) to measure the cable delay to the antenna, and I 
>> spent yesterday making up six matched cables to go from the splitter to 
>> the receivers -- they all test within about 1 nanosecond of each other.
>>
>> Obsessive compulsive?  Me?
>>     
>
> At the lab I worked at in the 80's, all the cables hanging on
> the wall-racks were calibrated and labeled in nanoseconds.
>
> But... after the ECL signals got turned into TTL, we just didn't
> care anymore :-).
>
> Tim.
>
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>   
John

Your not quite obsessive enough.
The cable delays (including the antenna to splitter cable) should also 
be a multiple of half the signal period to minimise the effects of 
residual mismatches at either end of the cable.

Bruce



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