LimeSDR output power during GSM set up

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Harald Welte laforge at
Tue Dec 15 10:23:19 UTC 2020

A very later follow up, sorry:

On Fri, Dec 04, 2020 at 12:04:22AM +0300, Mario Lucas wrote:
> and as i understand the only option to vary / set up output power is through the → osmo-bsc →
> trx 0
>    nominal power 23
>    ! to use full TRX power, set max_power_red 0
>    max_power_red 20
> So does this mean that 23-20=3 dbm?

OsmoBSC and OsmoBTS have been developed primarily for GSM-specific radios with calibrated,
defined output levels.

Using a general purpose SDR we really have no way of knowing what the output power will be,
and it differs from unit to unit as well as on the frequency you use.  It's all a big mess :(

In the ideal world one would actually be able to purhcase factory-calibrated SDR
boards that came with a data file (or even stored on internal EEPROM) that would
tell you on which Tx port at which frequency and temperature dbFS (full scale)
results in what kind of absolute output power in dBm.

If the SDR manufacturers would ship such calibration data, life would be so easy.

- Harald Welte <laforge at>  
"Privacy in residential applications is a desirable marketing option."
                                                  (ETSI EN 300 175-7 Ch. A6)

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