RF power problems with current master of osmo-trx
andreas at eversberg.eu
Sat Jan 25 06:22:56 UTC 2014
Alexander Chemeris wrote:
> Could you please provide more details about your setup and experiments
> you did?
> E.g. what PC so you run it on, what is the CPU utilization, have you
> tried to run it with real-time priority, what exactly you feed into
> the osmo-trx and what do you see on your monitoring phone, how exactly
> long is "longer", etc
> We noticed, that Linux kernel 3.3 had issues with 1GbE chips from
> Intel, so we switched to the kernel version 3.8, which works stable.
> We use kernels from the stock Ubuntu Server 12.04.
sorry, but this was my fault. here is the reason why i have only RF
power on two slots:
- i configured TS 0 with CCCH and TS1..TS7 with SDCCH8
- i set bts type at osmo-nitb to "nanobts", which rejects SDCCH8 on TS2..TS7
- no "Set Chan Attr" was sent from osmo-nitb to osmo-bts for TS2..TS7,
so osmo-bts did not send SETTSC to osmo-trx.
the thing is that the transceiver will only send bursts to umtx, if
SETTSC was given. (makes sense)
i found out that sending no butsts from osmo-trx to the transceiver will
cause no RF output. this is why osmo-bts sends dummy bursts for the
first TRX, so there is RF power on all TS all the time. on other TRX,
osmo-bts send bursts, only if the logical channel (the bursts belong to)
is activated. this is the way it is done to reduce noise on the
spectrum. i can see it one the osmocombb-RSSI application. once a
channel was activeated, there will be RF power on the specific TS, even
when osmo-bts does not send bursts anymore. i guess that some filler
table of osmo-trx causes it. i think it would be nice if osmo-trx would
stop transmitting, when there are no more bursts comming from osmo-bts.
(at least after a while.)
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