[time-nuts] Followup (still want a GPS-type NTP refclock)

[Sarah White]

On 10/18/2012 1:20 PM, SAIDJACK at aol.com wrote:
> Let the GPS average the antenna position over a very long time.
>  
> On a good GPSDO one can select the number of averages, and the position  
> variance before the survey is finished, and the (now very precise) position is 
>  stored in memory.
>  
> Indoors this may take a very long time to do (weeks?), but should work too. 
>  The problem indoors is multi path, one never knows where the signal is 
> coming  from that is seen. Setting up signal squelch in the GPS really helps 
> with that,  for example the C/No could be set to a minimum of 35dB, and 
> anything below that  is ignored so only the strongest signals are used.
>  
> We made a customer's urban solution work that way, it effectively  deleted 
> all the multipath issues he had from adjacent high-rises, since the  
> multipath signal strengths yielded about 20 to 28dB C/No and were thus all  
> squelched, whereas the direct signals were 35 to 50dB C/No.
>  
> bye,
> Said

Wow thanks.

I've never seen such an insightful explanation for dealing with
multipath signal issues. Fortunately, I'm not doing this for any sort of
"for profit" purpose / just learning for now. This list really has a lot
of experts :)

-- Sarah

P.S. Sorry for the earlier PGP signatures... In the past 24 hours
someone pointed out to me, to paraphrase: "most of the people reading
this list aren't using email systems which make any use of the (rather
long) message validation blocks"