GPS issues on GTA02v4

SHAWN_LIN at fic.com.tw SHAWN_LIN at fic.com.tw
Tue Mar 4 02:12:56 CET 2008


Dear Daneil:
 

I am the hardware engineer dedicate to RF parts. After reading your statement about this issue, this issue may be caused by bad connection of internal GSP antenna. Some tests should be performed on your Neo. I will also send you two antennas. One is internal and the other one is external. 

1. Replace the new one on your Neo and check signal quality (In open-sky, the TTFF is less than 45s)

If the result follows my expectation, the reason for this issue may be repeat de-assembling to damage the RF cable of the internal GPS antenna. 

If not, I think you can do the next test 

2. Plug the external antenna in our Neo and check the signal quality 

If the GPS is normal, I think the RF switch circuit (ESD sensitive) is complete break-down. 

If the signal is still poor or the Neo can not get any satellite, the Neo you owned should be call backed and fix it. (GPS chips must be something wrong)

 

I will send you these two antenna as soon as possible. If any question, let’s discuss together. 

 

Best regards, Shawn

 

________________________________

From: openmoko-kernel-bounces at lists.openmoko.org 代理 Daniel Willmann
Sent: 2008/3/4 [星期二] 上午 07:06
To: openmoko-kernel at lists.openmoko.org
Cc: DKAY_CHEN [陳南廷]; TIM_LEE (李國平經理); ALLEN_CHANG (張吉隆)
Subject: GPS issues on GTA02v4



This mail is mainly an FYI if some GPS related issues creep in along the
road. My problems are probably caused by poor SMT during the GTA02v4
run.

See also
http://lists.openmoko.org/pipermail/openmoko-devel/2008-February/001981.html
for my problem report earlier.

I first really tested GPS on my 2v4 on the train ride from FOSDEM where
the GPS managed to get a pretty good fix even through the window of the
ICE (the navilock GPS receiver I tried didn't).
A couple days later I was again travelling by train and this time the
Neo wouldn't even acquire the time. When I tried again at home the
result was still the same, no fix, no satellites, no time.
I played around with the connector of the internal GPS antenna,
applying pressure, and the GPS managed to get the time and see some
satellites for a short time, but that was it. After that I wasn't able
to reproduce any positive results with the internal antenna anymore (I
also tried different antennas). Attaching an external antenna worked
however and I was able to get the time in ~20s and a fix in additional
20s so GPS itself still seems to work.

At the moment I'm suspecting that either the phantom voltage for the
internal antenna or the antenna switcher is broken.

Regards,
Daniel Willmann


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