[time-nuts] Trimble Thunderbolt - Receive Sensistivity

Predrag Dukic stijena at tapko.de
Thu Aug 28 19:04:41 EDT 2008

I also had the same feeling until I changed the position of the 
antenna from eastern side of the building to the southern.

At least two usable svs more on the average...

P. Dukic

At 19:05 28.8.2008, you wrote:

>The Thunderbolt does not seem to be the most sensitive receiver 
>around,  but it does not seem particularly bad.  Sensitivity in a 
>time receiver can be a bad thing...  more sensitivity tends to make 
>it more susceptible to multipath, etc.  These things were meant to 
>be mounted on cell towers, etc where they have a pretty clear view 
>of the sky.  Once you have that,  you don't need high 
>sensitivity.  Also their proximity to high power RF transmitters 
>makes overly sensitive front ends a problem.
>On the subject of GPS amplifiers...  adding external amplification 
>to a GPS may not improve its performance and can actually degrade 
>it.  All amplifiers amplify signal and noise,  plus distort 
>everything in the process. (fundamental laws of the universe: 1) You 
>can't get something for nothing,  2) You can't break even,  3) 
>You'll die trying)   Ideally,  you want the amplifier at  the 
>antenna and you want the amplification to match the cable loss and 
>no more.  Generally GPS receivers with poor sensitivity have poorly 
>designed front ends or signal processing.  Yelling in their ears 
>won't make them work any better.
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