[Gta04-owner] GTA04A4 starts shipping tomorrow

Lionel Broche lionel.broche at gmail.com
Tue Jan 31 11:23:01 CET 2012


Interesting... I am surprised that a hand can influence the signal so much.
Maybe it would be worst investigating what kind of material are most
transparent to satellite RF signal to design the casing.

Lionel

On 31 January 2012 18:53, Dr. H. Nikolaus Schaller <hns at goldelico.com>wrote:

>
> Am 31.01.2012 um 00:47 schrieb Lionel Broche:
>
> > Good job, keep up with the good work!
> > How does the GPS performs now, with the HW fix and internal antenae?
>
> Much better than before. It is possible for an indoor situation to get
> time within
> 10 seconds and date within 20. And 3 or more satellites within 30-40
> seconds.
> In a cold start situation.
>
> As soon as the receiver starts tracking and knows its position, it even
> increases
> its sensitivity so that you can get 6-8 satellites.
>
> Generally an external antenna is still better and I have seen it receiving
> and
> using for navigation 11 of 12 possible satellites.
>
> SNR values I have seen is in the 15-35 dB range (indoors) with internal
> antenna and 25-45 with external. Getting a low TTFF needs 3 satellites
> above approx. 28 dB. The receiver may track them down to approx. 15 dB
> before loosing them. So it has a very wide dynamic range.
>
> Of course there are still many factors influencing sensitivity. Just
> holding
> your hand in 5-10 cm distance in the direction of the strongest satellites
> may reduce the SNR by 5dB. And, heavy SD card activitiy is also still
> recognizable.
> E.g. copying files may also reduce by 5dB while this is in progress.
>
> But in my subjective impression it is better than randomly picked GTA02
> (there
> has been a wide variance between good and not so good devices).
>
> Nikolaus
>
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