Using WBFM block

GNU Radio
1

Hi All,
I am doing simple wide band FM…The flowgraph is as attached…When i
execute it i am getting following error:

gr_remez: insufficient extremals – cannot continue
Traceback (most recent call last):
File “/home/ali/Desktop/top_block.py”, line 109, in
tb = top_block()
File “/home/ali/Desktop/top_block.py”, line 75, in init
max_dev=4000000,
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/analog/wfm_tx.py”,
line 69, in init
40) # stopband atten dB
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/filter/optfir.py”,
line 55, in low_pass
taps = filter.pm_remez (n + nextra_taps, fo, ao, w, “bandpass”)
File
“/usr/local/lib/python2.7/dist-packages/gnuradio/filter/filter_swig.py”,
line 466, in pm_remez
return _filter_swig.pm_remez(*args, **kwargs)
RuntimeError: gr_remez: insufficient extremals – cannot continue

Is the quadrature rate and audio rate are high?

2

Given your question, I think you already know the answer. 2MHz is far
from audio. Please refer to the wbfm example in GNU Radio, which has
sane parameters.

Greetings,
Marcus

3

On Thu, Jun 5, 2014 at 4:37 AM, jason sam [email protected] wrote:

ok.Then how can i achieve FM for greater deviation.i.e. in MHz range in
GRC?

What you’re seeing is a result of the Remez algorithm in the optfir
module
not properly converging. Why isn’t always clear; you can either tighten
up
or loosen the demands on the filter being built to try and fix it. You
could also go into the code and replace the optfir call with firdes. The
resulting filter might not be as good as you want and more taps, but it
will at least always build.

Tom

4

ok.Then how can i achieve FM for greater deviation.i.e. in MHz range in
GRC?

On Thu, Jun 5, 2014 at 1:18 PM, Marcus Müller [email protected]