joerg wrote:
Am Di 25. März 2008 schrieb Sean Chiang:
HI!
I'm trying to clarify the T-mobile oscillation issue. my testing result
so far:
Graeme's neo + T-mobile pre-paid sim --> 18 times re-camping to network
in 10 minutes
My neo's + T-mobile pre-paid sim --> 17 times re-camping to network
in 15 hours
These two neos have the same kernel, uboot, rootfs, gsm firmware, IMEI,
and tested at the same location.
I don't think this problem comes from gsm firmware side, there might be
something wrong at gsm module.
I'm not sure which part exactly. So I'll keep digging with TI( :-( :-(
:-( ) and try to figure out if our gsm module
is really broken, how to find them in factory.
Hi Sean,
check for RF-emission spectrum/amplitude of both NEOs. To make sure there's
not a spike harmonic interfering with the exact GSM control channel
frequency. Some PPM offset of any clock in the other NEO may shift such a
spike out of "danger zone". Dependency regarding different provider's cards
is via the channels used by the specific provider, even when both are e.g.
850MHz, their channels (and thus exact frequencies) are different for any
given location.
Another idea to check for is bad connection of GSM antenna in one of the NEOs.
Great point. The GSM antenna makes contact with the main board via a
metal tab with a dimple which presses against a pad on the main board.
When the main board is inserted into the case, care must be taken to
ensure this tab is in the right place. It is easy for it to get caught
under the board in which case the dimple does not make contact.
Worse, I have seen two GSM antennas with this metal tab broken, probably
as a result of getting caught under the board and then bent too far as
the board was forced into place.
Michael
