When I run ccch_scan on a regular network, every once in a while, at random I find the app stops sniffing with the error:
<000c> l1ctl.c:291 BURST IND: @(1428545 = 1077/01/35) (-105 dBm, SNR 3, SACCH) <000c> l1ctl.c:114 FBSB RESP: result=255
At the same time Osmocon gives a message like the following:
=> DSP reports FB in bit that is 1031487569 bits in the future?!? Synchronize_TDMA LOST 2313!
The problems seems therefore to emerge from some corruption of data in reception which causes l1ctl.c to dispatch the S_L1CTL_FBSB_ERR signal.
Can Holger or Harald who have written ccch_scan please confirm if this is the correct way to fix the problem or if there is better solution? Can you please also insert the update in the ccch_scan code in the burst_ind branch so that others can benefit?
It's not a correct fix, that's just a work around that basically says "Try to sync endlessly until it works" ...
Finding out _why_ the sync failed in the first place is the correct fix, which also would most likely fix the border case where you get bits errors (that case is triggered when the firmware thinks it has successfully synced but in fact didn't).
Cheers,
Sylvain
baseband-devel@lists.osmocom.org
-
Bhaskar11 -
Sylvain Munaut