[Discuss-gnuradio] WBX CW transmit problem

[Aleš Povalač]

Dear all,

I have been testing USRP2 with WBX board (#957). Using GNU Radio, I
have created a simple CW TX system. The problem: output signal is
oscillating when I set the TX frequencies to 900MHz band. Signal
output (in time domain) at TX/RX connector from the FSL analyzer is in
the attachment.

Settings:
868 MHz, 200 kSps, gain 15 dB

Same results with:
./tx_waveforms --rate 250000 --freq 868000000 --gain 15

The oscillation with ca. 1dB amplitude is present for almost all gain
settings except the lowest values. I have observed the problem at
several frequencies from 700M to 1G, sometimes with amplitude over
2dB.

Any ideas about the cause of this problem? Some PA instability or AGC
loop issue?

Thanks,
Ales

KMIT_001.PNG
Description: PNG image