Hi John,
more of a note pad than an email:
*PFB*
> firdes.low_pass(2.0, oversampled_width, fm_dev*2 ,1000,
> firdes.WIN_HAMMING, 6.76)
low_pass(double gain, double sampling_freq, double cutoff_freq, double
transition_width, gr::filter::firdes::win_type window, double beta=6.76)
pfb_taps is (with some variable names simplified for clarity):
firdes.low_pass(2.0, oversampled_width, fm_dev*2 ,1000,
firdes.WIN_HAMMING, 6.76)
where oversampled_width = channel_width * (num_chan + 1)
for channel_width = 15 kHz, fm_dev = 5 kHz, and num_chan = 7.
For what it's w
what's the pfb_taps design spec? (i.e. what did you use as argument for
firdes.lowpass()?)
Best regards,
Marcus
On 05/24/2017 04:38 PM, John Ackermann N8UR wrote:
> Here's the whole flowgraph.
>
> Once I get the code functioning, I'm planning to clean this up, maybe
> add a few more channels, a
Interesting point, Marcus. I'll post the complete flowgraph tomorrow when I am
at my development machine. I did revert the audio rate out of the demod to
15ksps and that helped somewhat. So maybe that can go further.
On May 23, 2017, 7:18 PM, at 7:18 PM, "Marcus Müller"
wrote:
>Hi John,
>
>
Hi John,
3 to 5 seconds doesn't sound all that much considering that you're doing
stuff at a nominal 7.5 kS/s – compare [1]; the typical buffer size
between two blocks is 8 kB, and with floats (i.e. 32 b = 4 B), that's
2000 S, and at 7.5 kS/s, that's 2/7.5 s = 0.26667 seconds for the
buffers betwe
Hi Marcus and Kevin, and thanks for the info.
I've set all squelch gates off. In that case, I get good audio if "OK
to block" in the audio sink is set to "yes" but the latency is awful --
3 to 5 seconds! If "OK to block" is "no", then I get lots of aU and
unusable audio.
If setting the squ
Hi JOhn,
you mustn't gate=yes in the squelch! The "add" block needs an input
sample on every input to generate one sum sample, and thus, every
squelch that's currently gating (i.e. not generating any samples) will
simply stop the complete flow graph.
The rest looks ok (if you really feed in 15 kH
On Tue, May 23, 2017 at 11:31 AM, John Ackermann N8UR wrote:
> I'm continuing to work on a multi-channel NBFM receiver using the
> polyphase filter. I have the basic system working, but am hung up on how
> to get audio out of the system; most of my attempts end up either with
> audio underruns,
