On 09/08/13 00:22, Vanush Vaswani wrote:
Hi,
If i add a rational resampler to match the audio rate before the UDP
sink, I can get a continuous output, but it's of terrible quality due to
the loss of information.
You are always going to have to throw information away. You have 192k
that you are trying to fit into human hearing, so you *must* filter
and then down sample.
How wide is your BPF/LPF ? Is it more than your soundcard can handle ?
How does the flowgraph work having a sample rate 'mismatch' when the
FCDPP block is in the same graph?!
Your soundcard (probably) expects 44k1. The resampler takes care of
this, but of course, 192k is not going to go into 44k1. You need to
filter first.
Could you give me a hint in working around this issue?
As I said before, google has plenty of examples of FM receivers with grc
(Google for gnuradio FM receiver grc, I'm sure you'll find loads)
Here are two working flowgraphs that start at 192k and 250k
respectively:
http://hal.g7iii.net/GRC/Examples/Simple_Multimode_RX.png
http://hal.g7iii.net/GRC/Examples/GUI_TRX_JACK.png
They are actually a multimode receiver I wrote as an example for a
friend, and a multimode transceiver for ham radio use, but they show
the FM receive chain.
With both, you'll note I have a variable BPF so I can listen to
broadcast stations on MW/LW, and FM, SSB, or CW stations on the amateur
radio bands.
For pure FM you can drop the selector blocks, and just concentrate on
the NBFM receiver chain
Note if you need to be tuning with the FIR filter, you'll need to define
filter taps. I used a simple LPF.
Hope that helps
Iain
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