Re: [Discuss-gnuradio] fft sink x-axis units

[Dan Halperin]

Eric Hill Matlis wrote:

Thanks for the response.  I guess my question is: where is that information carried?  Is it in the definition of the source?  The two definitions of the sinks look virtually identical to me:

am_rcv.py:
            pre_demod = fftsink.fft_sink_c (self, panel,
            title="Pre-Demodulation", fft_size=1024, sample_rate=if_rate)
            self.connect (src, pre_demod)
            vbox.Add (pre_demod.win, 1, wx.EXPAND)

usrp_wfm_rcv_pll.py:
            self.src_fft = fftsink.fft_sink_c (self, self.panel,
            title="Data from USRP",fft_size=512, sample_rate=usrp_rate)
            self.connect (self.u, self.src_fft)
            vbox.Add (self.src_fft.win, 4, wx.EXPAND)

eric

I haven't looked at the code carefully, but "if_rate" and "usrp_rate" sure look suspicious given that IF usually stands for Intermediate Frequency. Here is a relevant-looking part of fftsink.py

        x = max(abs(self.fftsink.sample_rate), abs(self.fftsink.baseband_freq))
        if x >= 1e9:
            sf = 1e-9
            units = "GHz"
        elif x >= 1e6:
            sf = 1e-6
            units = "MHz"
        else:
            sf = 1e-3
            units = "kHz"

-Dan