Re: [gpsd-users] Acquiring a Navisys GR[67]01W (was: GR-301W)

[Thomas P.]

Hi, 


On Wednesday 19 November 2014 12:05:42 Gary E. Miller wrote:
> My experience says otherwise.  I find the uBlox6 and SiRF III have no
> trouble in most buildings I am in.  And not on the edge, quite strong.
> I do agree that steel and/or tall building are very hard on a GPS
> signal, but that is not something I often see.
Maybe a difference between Europe and US. Here you will hardly find any 
buildings where it works and even trough modern windows its hard. 

> > But I would not expect, 1dB more or less sensitivity such a chipset
> > version has more or less would make a difference. (And newer chipsets
> > typically have better sensitivity than olders)
> 
> My experience says otherwise.  Many of the newest GPS chips have
> emphasized power saings over receiver sensitivity.  Way more than dB.
> For example, I find the SiRF IV to perform very poorly compared to the
> SiRF III.

What I quickly can find:
Sirfstar3 -159dBm sensitivity 
(http://www.globalsources.com/gsol/I/GPS-module/p/sm/1025755241.htm#1025755241)
Sirfstar4 -163dBm sensitivity (http://www.csr.com/products/35/sirfstariv-gsd4e)

Well, this numbers say at least, but should be in a theoretic scenario equal, 
with a tendency the SS4 is a bit better. 

However, such a difference could be easily overridden by poor antenna/PCB 
design, choosing a cheaper LNA etc. 

Also other effects like fading or spur tones might harm the one or other 
receiver more or less. Could be again that e.g. somebody uses a cheaper filter 
after the antenna. 

Kind regards, 

Thomas