[time-nuts] Low SNR GPS reception and cheap LNAs

Bob Camp lists at rtty.us
Sat Apr 26 08:20:47 EDT 2014


Hi

The ability of these receivers to handle noisy signals depends on a lot of things. The good stuff seems to have a massive number of correlators. Going from a 1.3 to a 0.3 db nf amp likely only helps you by 1 db. The low correlateor GPS’s are / were 10 to 20 db less sensitive than the newer stuff. 

Bob

On Apr 26, 2014, at 6:52 AM, Attila Kinali <attila at kinali.ch> wrote:

> On Sat, 26 Apr 2014 12:25:11 +0200
> Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
> 
>> If you have a passive antenna, put a LNA right at the antenna, since any 
>> cable damping will cause the S/N to go down. Also, if you put an 
>> aditional amplifier in line, your want that too up at the antenna.
>> Then, low-loss cable should be natural.
> 
> My current antenna is an cheap patch antenna. It has an LNA, but aparently
> it's not enough. I talked with a few gnuradio people and they basically
> told me that the GNSS-SDR software needs a strong signal for acquisition.
> Ie. i realy need to put the antenna somewhere with good skyview.
> 
> I ordered 4 of those lna4all, so that problem should be solved.
> 
> I'm also getting a better antenna and we'll see how much signal i can
> get out of this place.
> 
> 			Attila Kinali
> 
> -- 
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