osmo-trx issues

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Max msuraev at sysmocom.de
Thu Jun 16 08:55:34 UTC 2016


Hi.

A little follow-up.

When testing calls after manual poweron using clkind branch of osmo-trx
I've noticed following:

WARNING 3077733184 10:50:06.4 Transceiver.cpp:749:driveControl:
NOHANDOVER at timeslot 1 subslot 0
WARNING 3077733184 10:50:08.2 Transceiver.cpp:749:driveControl:
NOHANDOVER at timeslot 1 subslot 0
WARNING 3077733184 10:50:08.2 Transceiver.cpp:749:driveControl:
NOHANDOVER at timeslot 1 subslot 0
WARNING 3077733184 10:50:12.0 Transceiver.cpp:749:driveControl:
NOHANDOVER at timeslot 2 subslot 0
WARNING 3077733184 10:50:13.0 Transceiver.cpp:749:driveControl:
NOHANDOVER at timeslot 2 subslot 0
WARNING 3077733184 10:50:32.2 Transceiver.cpp:749:driveControl:
NOHANDOVER at timeslot 2 subslot 0
WARNING 3077733184 10:50:32.5 Transceiver.cpp:749:driveControl:
NOHANDOVER at timeslot 2 subslot 0

Looking at the code which produced it does not reveal much - just a
debug print upon reception of some command. Why is it a warning? What's
bad about it?

On 06/13/2016 06:58 PM, Alexander Chemeris wrote:
> Hi Max,
>
> On Mon, Jun 13, 2016 at 6:15 PM, Max <msuraev at sysmocom.de> wrote:
>> While running osmo-trx with B200 I've noticed following log messages
>> repeated multiple times:
>>
>> 1) WARNING 3011271488 16:59:00.1 Transceiver.cpp:674:pullRadioVector:
>> Clipping detected on received RACH or Normal Burst
> This means that your phone transmit at a level which saturates BTS's
> receive chain. Osmo-trx can't demodulate the signal and prints this
> message.
>
> I don't have much experience with USRPs, but general way to avoid this is:
> 1) Decrease "ms max power", so that phone starts with lower power,
> 2) Reduce "rxgain" in osmo-bts config
> 3) Add an attenuator to your Tx/Rx chains.
>
>> 2) ERR 3011304256 16:58:12.9 UHDDevice.cpp:1512:write: Skipping buffer
>> data: timestamp=210353475 time_end=202360063
> This means that you're loosing samples between the device and UHD.
> Can't help you much here, because it's device specific. May be Thomas
> can suggest something.
>
> This is not the end of the world, but it may lead to all kinds of
> unstable behavior similar to when you have really bad radio link and
> bursts are dropped randomly.
>
>

-- 
Max Suraev <msuraev at sysmocom.de> http://www.sysmocom.de/
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