[time-nuts] Trimble Thunderbolt - Receive Sensistivity
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...
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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