----- Original Message -----
From: Martin Dvh <[EMAIL PROTECTED]>
Date: Monday, April 17, 2006 3:06 pm
Subject: Re: [Discuss-gnuradio] Basic USRP AM Transmission
> Robert Roberts wrote:
> > Hello everyone,
> >
> >
> > I have been experimenting with the Flex400 board and have been
> trying to
> > implement a basic AM transmitter. I have a WFM and NFM transmitter
> > working, but I cannot get the AM one to transmit correctly. The
> code> below generates a much higher frequency tone. Any advice to
> what I am
> > doing wrong? Does my output need filtering before connecting to
> the> sink?
> >
> >
> > self.u = usrp.sink_c () # the USRP sink
> >
> > # Code here for setting up the USRP, omitted
> >
> > src = gr.file_source (gr.sizeof_float, "audio-1.dat", True) #
> 440Hz tone
> > file
> What is the sample_rate of the audio file
> What is you interpolation rate of the usrp
> What is the duc frequency of your usrp.
I have the file source sampled at 32kS/s
I use the following code for setting up my usrp:
self.dac_rate = self.u.dac_rate() # 128 MS/s
self.usrp_interp = 400
self.u.set_interp_rate(self.usrp_interp)
self.usrp_rate = self.dac_rate / self.usrp_interp # 320 kS/s
self.sw_interp = 10
self.audio_rate = self.usrp_rate / self.sw_interp # 32 kS/s
# determine the daughterboard subdevice we're using
if options.tx_subdev_spec is None:
options.tx_subdev_spec = usrp.pick_tx_subdevice(self.u)
m = usrp.determine_tx_mux_value(self.u, options.tx_subdev_spec)
self.u.set_mux(m)
self.subdev = usrp.selected_subdev(self.u, options.tx_subdev_spec)
print "Using TX d'board %s" % (self.subdev.side_and_name(),)
self.subdev.set_gain(self.subdev.gain_range()[1]) # set max
Tx gain
self.set_freq(options.freq)
self.subdev.set_enable(True) # enable
transmitter
This is the same code I used for both a NFM and WFM transmitter, both of
which appeared to transmit without problems.
Sincerely,
~Chris~
> If the sample rate of your audio file is for example 48000 Herz
> Then the usrp interpolation rate should be 128000000/48000 = 2666
> Which is I think way out of range for the usrp
> You first have to interpolate in software to something in the range
> of the usrp.
>
> Greetings,
> Martin
> > const = gr.add_const_ff (1.0)
> > conv = gr.float_to_complex()
> >
> >
> > gain = gr.multiply_const_cc (4000.0) # transmitter gain
> >
> > # connect it all
> >
> > self.connect (src, const)
> > self.connect (const, conv)
> > self.connect (conv, gain)
> > self.connect (gain, self.u)
> >
> >
> >
> >
> > Thanks,
> > ~Chris~
> >
> >
> >
> >
> > _______________________________________________
> > Discuss-gnuradio mailing list
> > Discuss-gnuradio@gnu.org
> > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >
>
>
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