[Discuss-gnuradio] Re: unknown peak in the FFT-Plot Sink

[feldmaus]

Paul Mathews <opto <at> whidbey.com> writes:

> 
> Use an Intermediate Frequency (IF) and frequency translating filter. 
> Paul Mathews
I still use the IF by tune my usrp source with,
usrp.tune(self.usrp_source, 0, self.selected_device, self.usrp_freq)

But i think you mean to tune the "frequency translating filter" ?!
Therefor i want to know what is <tabs> ?
I read <channel filter>. Is this equivalent to <bandpass filter> 
or do you mean the IO-Ports from the DA-converters  ?

Sorry but i didn't learned the english translated technical term.

How to fit up this <frequency translation filter> ?
# USRP SOURCE
self.usrp_simple_source_x = grc_usrp.simple_source_c(which=0, side='B',
rx_ant='RXB')
self.usrp_simple_source_x.set_decim_rate(decim)
self.usrp_simple_source_x.set_frequency(freq, verbose=True)
self.usrp_simple_source_x.set_gain(gain_usrp_source)

# FREQU. TRANS. FILTER
self.gr_freq_xlating_fir_filter_xxx_0 = gr.freq_xlating_fir_filter_ccc(decim,
(1, ), freq, samp_rate)

# FFT PLOT SINK
self.wxgui_fftsink2 = fftsink2.fft_sink_c(
        self.GetWin(),
        baseband_freq=0,
        y_per_div=10,
        y_divs=8,
        ref_level=80,
        sample_rate=samp_rate,
        fft_size=512*2,
        fft_rate=20,
        average=True,
        avg_alpha=None,
        title="FFT Plot",
        peak_hold=False,
        )

When i start this, it seems to be busy !
When i tune the freq with my slider, all 3 elemts will be tuned.
Is this correct?
Or should i set up the baseband frequency of the fft plot to 0Hz ?

Any Hints ?

Regards Marksu