osmo-trx peculiarities in dual-channel mode

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Thomas Tsou ttsou at vt.edu
Sat Jul 13 16:39:08 UTC 2013


On Sat, Jul 13, 2013 at 5:45 PM, Alexander Chemeris
<alexander.chemeris at gmail.com> wrote:
> What is the reason you disabled setting power attenuation an receive
> gain for the second trx? Since both channels in UmTRX are independent,
> it should be possible to control tx power and rx gain independently.
>
> In the "SETPOWER" command handler:
>       if (mPrimary)
>         mRadioInterface->setPowerAttenuation(dbPwr);

The control interface was setup for OpenBTS, which does not make a
distinction between independent channel gain. So I locked both gain
settings to the primary channel (the one that initializes the device).

For better osmo-bts usage, I split the gain settings in the same way
that we discussed for the tuning setting. Note that this breaks
OpenBTS usage, but that fix should really be in core and not the
transceiver.

  git://github.com/ttsou/openbts-p2.8.git  umtrx_dual_test

> In the "SETRXGAIN" it's even stranger, as it's set twice in case of primary trx:
>     newGain = mRadioInterface->setRxGain(newGain);
>     mEnergyThreshold = INIT_ENERGY_THRSHD;
>     if (mPrimary)
>       newGain = mRadioInterface->setRxGain(newGain);

Very strange indeed. That's a bug. Fixed in the same patch.

  Thomas




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