[Discuss-gnuradio] regarding connecting SNR block in benchmark_rx

[shantharam balasubramanian]

Hi

I have been working with gnuradio python programs for my project and I am trying to collect SNR data for the signals I receive using benchmark_rx.py. 

I have been dealing with connecting an SNR block in the benchmark_rx.py and I came across a block called, "gr.probe_mpsk_snr_c(thresh)", which is in the receive.path.py.

Unfortunately, I am not very familiar with connecting blocks and using them in gnuradio python programs. I have asked gnuradio people before regarding connecting a block to collect the data about power of the signal received.

I then received an email explaining to me about doing it by including the following statements and it worked perfectly.

        self.probe = gr.probe_avg_mag_sqrd_cf(thresh,alpha)
        self.power_sink = gr.file_sink(gr.sizeof_float, "rxpower.dat")
        self.connect(self.probe, self.power_sink) # should dump the power values in a file.....hopefully....         
        # Set up receive path
        self.rxpath = usrp_receive_path.usrp_receive_path(demodulator, rx_callback, options)

                #connects#
        self.connect(self.rxpath)
        self.connect(self.rxpath.channel_filter,self.probe)

I was then trying to use the similar list of commands to calculate the SNR using the block "gr.probe_mpsk_snr_c(thresh)" but it didnt work. I then tried the following statements,

        self.probe = gr.probe_mpsk_snr_c(thresh)

        self.rxpath = usrp_receive_path.usrp_receive_path(demodulator, rx_callback, options)

        self.connect(self.rxpath)

        self.connect(self.rxpath.channel_filter,self.probe)

  

But the receiver didnt receive anything properly and it was printing out weird symbols.

It will be really helpful if someone can explain to me about connecting this block and measure the SNR.

Thank you

--
Regards

Shantharam Balasubramanian
MS in Electrical and Computer Engineering
Rutgers University
Ph:732-543-6863
Email:address@hidden