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Automatic update of USRP RX gain during initial search using --agc option

Raghavendra Dinavahi requested to merge NR_UPDATE_RXGAIN into develop
  • if search fails, keeps increasing the rx gain (set by --ue-rxgain) by 3 db until USRP max rx gain
  • if initial sync is success, sets the rxgain to the value of (TARGET_RX_POWER (50) - pbch digital power in dB/RE)

Manually setting ue-rxgain for different USRPs takes time (especially in OverTheAir testing) using OAI UE. using this option (--agc) rxgain will be gradually increased by 3dB until PBCH/PSBCH is read successfully during initial sync.

Example log:

[HW]     Actual RX gain: 25.000000...
[PHY]   [UE thread Synch] Running Initial Synch 
[HW]   Setting USRP RX gain to 28.000000 (rx_gain 28.000000,gain_range.stop() 75.000000)
[PHY]   synch retry: with higher rxgain 28 dB, increased by 3 dB, (max 75 dB) 
[HW]   Setting USRP RX gain to 31.000000 (rx_gain 31.000000,gain_range.stop() 75.000000)
[PHY]   synch retry: with higher rxgain 31 dB, increased by 3 dB, (max 75 dB)
[HW]   Setting USRP RX gain to 34.000000 (rx_gain 34.000000,gain_range.stop() 75.000000)
[PHY]   synch retry: with higher rxgain 34 dB, increased by 3 dB, (max 75 dB) 
[PHY]   Initial sync: pbch decoded sucessfully, ssb index 0
[HW]   Setting USRP RX gain to 37.000000 (rx_gain 37.000000,gain_range.stop() 75.000000)
[PHY]   Got synch: adjusted rxgain 3 dB, (max 75.000000 dB)
Edited by Robert Schmidt

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