Does the cell network code hate being in a mobile device?

asked 2014-10-25 23:57:34 +0300

eskild gravatar image

updated 2014-10-25 23:59:59 +0300

Whenever I try to use the cellular network on my Jolla on the bus or in a train, it keeps crashing on me. On and on and on, the record being somewhere around 10 reboots on a 30-minute trip. When I stop moving, i.e. get off the train, the reboots stop.

While on the train I've also tried not entering my SIM pin, and then the phone doesn't reboot. When I re-activate cellular, boom. Sometimes it crashes within maybe 5 seconds after entering the pin.

This has been a problem for for months and months and it's still present on 1.1.0.39. Frankly, I'm just about to give up on my Jolla because of this.

If anybody has an idea about how to hone in on the root cause, I'm all ears. The crashes are just so sudden and without warning that anything along the lines of "fire up a terminal, run 'whatever' and see what it says" probably won't work.

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Really strange, that it is so frequent with you.

I had that happen to me once, long time ago when I was in a basement location where the cellular field dropped to zero. Also had that problem once with my N9 years ago in the same place.

juiceme ( 2014-10-26 00:02:12 +0300 )edit

Please try cleaning battery contacts. :) https://together.jolla.com/question/57254/personal-log-battery-contact-issue-observations/

tigeli ( 2014-10-26 01:08:27 +0300 )edit

There have been similarly reports by other users, also involving a mobile connection (possible together with bad reception), coupled with excessive battery drain. My bet is still on a hardware problem somewhere.

dthierbach ( 2014-10-26 12:45:09 +0300 )edit

Thanks for the input. I'll try getting hold of something to clean the contacts with, and then we'll see how it goes.

But even if it's related to contact resistance it would seem to me that whatever control circuitry there is (hw/sw/both in concert), isn't responding optimally.

eskild ( 2014-10-26 20:16:12 +0300 )edit

Actually it is pretty logical that large resistance in the battery contacts would lead to all kinds of system haziness when the device is in poor network coverage; The device tries to send with increasing power to be heard with the BTS, and this leads to higher current drain from the battery which starts dropping voltage over the contact resistance. When the voltage drops below the threshold that the regulators can compensate for, the device reboots.

juiceme ( 2014-10-26 20:28:09 +0300 )edit

Yes, expect from what I read from other reports this doesn't sound like a simple Ohm's law kind of thing: Sometimes a phone comes back with more charge reported than prior to the reboot, sometimes the drop is very rapid. It smells more like a control issue of some sort. Anyway, it's all just speculation without measurement. I hope Jolla's looking into it.

Again, thanks for input.

(Edit: It sounds a bit weird that this transmit-power increase doesn't trigger low-battery warnings. I would expect better from a phone simply because one day it'll have to deal with an aging battry. I kind of consider it "bad style" :-) to reboot without warning just because the battery is getting old.)

eskild ( 2014-10-26 21:12:11 +0300 )edit