My advice is to get this all figured out in software before using any
hardware (usrps and spectrum analyzers).
You can simulate the effect of changing the max deviation all in
software using a noise source, throttle, nbfm tx block, and an fft sink
(all in grc).
I guarantee that changing max deviation from 5 to 50k makes a big
difference.
-Josh
nansai hu wrote:
I want to design a FM radio with freq deviation can be change.
Then I tried to modified an example in GNUradio example folder which name
"fm_tx4.py" in line61,let max_dev=5 to 50K,shown in following yellow label.
but there is no change at all in a spectrum analyzer.
Help me,thanks
class pipeline(gr.hier_block2):
def __init__(self, filename, lo_freq, audio_rate, if_rate):
gr.hier_block2.__init__(self, "pipeline",
gr.io_signature(0, 0, 0),
# Input signature
gr.io_signature(1, 1, gr.sizeof_gr_complex))
# Output signature
src = gr.file_source (gr.sizeof_float,'/home/sdr/Desktop/hu/1.wma',
True)
fmtx = blks2.nbfm_tx (audio_rate, if_rate, max_dev=5, tau=75e-6)
# Local oscillator
lo = gr.sig_source_c (if_rate, # sample rate
gr.GR_SIN_WAVE, # waveform type
lo_freq, #frequency
1.0, # amplitude
0) # DC Offset
mixer = gr.multiply_cc ()
self.connect (src, fmtx, (mixer, 0))
self.connect (lo, (mixer, 1))
self.connect (mixer, self)
------------------------------------------------------------------------
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