On Tue, Jun 16, 2009 at 09:15:34PM +0800, Su Jinzhao wrote: > Hi, > > I want to read RSSI value using analog AUX ADC, I think we can read RSSI > through AUX_ADC_A1 pin of AD9862, I looked through the code > of usrp_read_aux_adc in file > /root/gnuradio/gnuradio-3.1.3/usrp/host/lib/legacy/usrp_primes.cc,
If you are using usrp_standard_rx, or gr.usrp_source_*, you can do this much more simply by using: adc_val = u->read_aux_adc(which_side, which_adc) http://gnuradio.org/doc/doxygen/classusrp__basic__rx.html http://gnuradio.org/doc/doxygen/classusrp__standard__rx.html You didn't mention which daughterboard you are using. Not all daughterboards have an analog RSSI output. > my question is: > 1.The AD 9862 specification says: "The AUX SPI can be enabled and configured > by setting register AUX ADC CTRL. Setting register use pins high enables the > AUX SPI port.", but in the above code AUX_ADC_CTRL_AUX_SPI was not set high( > In my opinion, aux_adc_control should be added with | = AUX_ADC_CTRL_AUX_SPI > because usrp_9862_write and usrp_9862_read all need SPI operation, so we > should enable AUX API), Is this a mistype or another method ? The code is correct. There are a couple of ways to use the AUX ADCs. We use them by polling, not over the AUX SPI bus. > 2.stefan.bruens in the list had said that the low 16 bits is the RSSI value, > I want to know why did the above code combine the high and low 16-bit and > format the data into 12-bit ? This is a digital RSSI, determined post high-speed ADC. You can look at the computation here: http://gnuradio.org/trac/browser/gnuradio/trunk/usrp/fpga/sdr_lib/rssi.v > 3. Even with the RSSI value (int type), what should I do to convert that > value into dBm unit ? You would need to calibrate the entire signal path. Left as an exercise... Eric _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
