discuss-gnuradio
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: FSK and Timing Recovery Questions


From: Barry Duggan
Subject: Re: FSK and Timing Recovery Questions
Date: Sat, 11 Jan 2020 18:29:06 -0500
User-agent: Roundcube Webmail/1.3.8

Hi Alex,

You might be interested in:
https://wiki.gnuradio.org/index.php/Sample_Rate_Tutorial#Source_hardware_example

It's a little different approach, but works very well. Contact me if you have any questions.

Happy New Year to you too.
--
Barry Duggan KV4FV

On Wed, 8 Jan 2020 13:57:09 -0600, Alex Roberts wrote:

Hello Mailing List,

Happy New Year!

I've been playing around with this (
http://aaronscher.com/GNU_Radio_Companion_Collection/Audio_Modem_loop_back_test_FSK.html)
FSK audio modem and have a few issues/questions.

1) Is the PFB block the way to go for FSK timing recovery? I have issues
where if I start the receiver before the transmitter, the system doesn't
work. And if I start the transmitter before the receiver, it will
eventually lose sync and never recover. I added a message strobe to send
dummy data once a second (like a keep alive/heartbeat) and this helps it
from losing sync in between time of when I send meaningful data.

1a) Reading docs on both PFB and M&M blocks, do I need a moving avg. filter
after quad demod to round out the square pulses to allow PFB and M&M to
better find peaks or is the moving avg filter implemented within the block?

2) Is the pre-amble being muxed doing anything more than just padding my
data to help the PFB lock in before actual data arrives?

3) Would the Correlation Estimator help since it can send "time_est" tags downstream to the PFB and if so, where would be the ideal place to put it?

Cheers,
Alex



reply via email to

[Prev in Thread] Current Thread [Next in Thread]