Hi Marcus, Thank you for your prompt response.
I can change the TX power, kindly find attached the received "I" channel in case of TX power -25 dbm and -45 dbm. Also, there is about 10 dB attenuation before the Ettus RX. As you can see, there are many samples that goes to +/- 2048 and I believe that means ADC is overloaded. It is mentioned in the reference manual of Ad9364: "When the ADC is overloaded, the error between its samples and the input signal will cause the ADC to output more samples with values of +4 or −4 as it struggles to track the input signal.", is there anything else I can try? Note: Disabling AGC and changing gains gives reasonable outputs (i.e., amplitude of samples change with changing the applied gain without samples going to +/- 2048). But I need to use AGC because I want to have "over the air" testing instead of cable testing. Also, I tried to use --args type=b200 but it did not help. Is it possible after loading and executing the script top_block_py (i.e., while USB port is used to stream I/Q) to send commands for the board to get sample rate, carrier freq., gains,....? Thanks again, Best Regards, Ahmed On Wed, Mar 28, 2018 at 12:29 PM, Marcus D. Leech via USRP-users < usrp-users@lists.ettus.com> wrote: > On 03/28/2018 11:32 AM, Ahmed Hamza via USRP-users wrote: > > Hi, > > I am using Ettus B200 mini, to receive signal at carrier frequency 725 MHz > and the bandwidth is 6 MHz. The sampling rate is set to 13.28 MHz. > > I enabled AGC by calling set_rx_agc() from set_gain inside > /usrp_source_impl.cc. > The thing is that I am receiving a signal with a maximum that reach +/- > 2048 frequently so I believe that the ADC is overloaded. The test is using > cable so it is supposed that there is no out of band interference. > > My questions are: > 1) Do you know what may be causing this behavior and what should I try? > 2) Where can I find the default values that Ettus B200 mini used for Ad9364 > registers? > 3) Is there a way to read and/or write values of Ad9364 registers? > 4) There are some get functions provided by Ettus, could this get > functions used in run time (I mean after loading the script)? For example, if > I do, uhd_usrp_probe --string /mboards/0/dboards/A/rx_ > frontends/A/gain/agc/mode/value after loading the script > I get: linux; GNU C++ version 5.3.1 20151219; Boost_105800; > UHD_003.009.002-0-unknown > Error: LookupError: KeyError: No devices found for -----> > Empty Device Address > > Thanks, > > Best Regards, > Ahmed > > > Reduce the power of the device that is sending the signal--use attenuators > if you have to. > > uhd_usrp_probe needs a device address: use --args type=b200 > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >
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