Hi, I'm having problems getting the correct (well..what I believe to be correct) gain out of the RFX 900 transceiver.
I have a input signal of around -50dBm going into the TX/RX port of the RFX900. I've bypassed the ISM filter. I have to turn the RF gain all the way to its maximum of 70dB, just to get a 0dBm signal at the A/D converter. Changing the PGA gain has no effect. As I turn down the RF gain, the input level drops accordingly. I've been using the C/C++ interface, so I used the write_aux_dac function to max out the RF gain as follows: m_uRx->write_aux_dac(1,0,(int) ceil(0.2*4096.0/3.3)). and the set_pga function to set the IF gain. So with 70dB total of combined front gain, I would expect that the input to the A/D would be saturated, i.e. full-scale, with a A/D input level of 10dBm. Some questions: -- I'm assuming the input impedance to the RFX900 is 50ohms. Is that correct? -- The RFX900 schematic shows 2 gain stages. The first is an LNA that provides 22dB, the second is the DDC which provides a max of 45dB and is adjustable via the aux DAC. So the RF gain is adjustable b/w 22dB and 67dB? I'd appreciate any answers, questions, or suggestions anyone might have. Thanks, Harvind _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
