diff options
| author | Andy Walls <awalls@md.metrocast.net> | 2016-03-30 09:15:45 -0400 |
|---|---|---|
| committer | Andy Walls <awalls@md.metrocast.net> | 2016-03-30 09:15:45 -0400 |
| commit | 515e40039e614ac86fb4c7be8dc4d067aa2bd9a3 (patch) | |
| tree | 0a9da028ca3ff74acdea28cb756fab363375b486 /gr-uhd/examples/python/fm_tx4.py | |
| parent | 2ae7809b845b7930c9b0120737167dd1251098eb (diff) | |
gr-analog: Add safety and default for FM preemphasis filter
The FM preemphasis filter design now precludes the user from
inducing a pole on the unit circle at z = -1.0 and z = 1.0.
A pole at either of these locations makes the filter unstable and
useless: feeding back "+/-inf" into an IIR filter has no good
recovery.
Also provide a reasonable, maximally safe default of 0.925*fs/2.0
for the high frequency corner, fh. This keeps the slope of the
preemphasis filter looking reasonable sane in the whole band; at
least for tau=75e-6 and fs=48000.
Diffstat (limited to 'gr-uhd/examples/python/fm_tx4.py')
| -rwxr-xr-x | gr-uhd/examples/python/fm_tx4.py | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/gr-uhd/examples/python/fm_tx4.py b/gr-uhd/examples/python/fm_tx4.py index ffc74abf82..516033dae1 100755 --- a/gr-uhd/examples/python/fm_tx4.py +++ b/gr-uhd/examples/python/fm_tx4.py @@ -63,8 +63,8 @@ class pipeline(gr.hier_block2): sys.exit(1) print audio_rate, if_rate - fmtx = analog.nbfm_tx(audio_rate, if_rate, max_dev=5e3, tau=75e-6, - fh=0.0) + fmtx = analog.nbfm_tx(audio_rate, if_rate, max_dev=5e3, + tau=75e-6, fh=0.925*if_rate/2.0) # Local oscillator lo = analog.sig_source_c(if_rate, # sample rate |