BTS using osmocombb trx

Christian Schulte cs at saturn2.franken.de
Wed Jan 29 16:36:31 UTC 2014


  Hello dear osmocom team

first off, thanks for all the work you have
put into this project. Its great to have a starting
point for toying with this new/old technology. ;)

I got myself a C155 and have used osmocom-bb on it
to read some traffic with wireshark. So far everything
works nicely.

Now i wanted to communicate with a second phone and
have tried setting up a BTS following this guide

http://openbsc.osmocom.org/trac/wiki/network_from_scratch
(using a single phone)

My problem is that the phone doesnt transmit anything.
Yes i have enabled the transmitter flag in the Makefile. ;)
When i use osmocon to load the TRX into the phone and start the
osmocom-transceiver i get this debug output from osmocon.

...
Synchronize_TDMA
=>FB @ FNR 26585 fn_offset=2002505 qbits=4924
LOST 1910!
BTS MODE: 255 65535 {0,0,0,0,0,0,0,0} TX 0..7 RX 0..7


After taking a look at the code the values seem weird
and they come from the transceiver function l1ctl_tx_bts_mode()
like that.
/host/layer23/src/transceiver/l1ctl.c:120

As a test i got the phone to transmit something by
overwriting the values on the TRX side.

I havent gone further yet but wanted to ask if someone could
maybe point me to an obvious mistake i did before i
spend more hours on this issue.
A hint as to how i enable the different logging settings
would be great as well.


  thanks,
  best regards, Christian






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