It is currently Fri Jan 22, 2021 10:36 pm

Click the link below to visit the site sponsor

The Ham Radio Shop

Post new topic Reply to topic  [ 1 post ] 
 FM with IQ 
Novice Member

Joined: Wed Aug 22, 2018 8:43 pm
Posts: 26
Location: Burnley, IO83VT
Feedback: 2 (100%)
Reply with quote
Post FM with IQ
Hi all,

In my spare time I've been trying to understand how different modulation types work with IQ signals. Thus far I've managed OOK and AM. I've now moved onto FM. I'm using:

out[i] = cos(X[i]) + j sin(X[i])

to create the output IQ sample from the input signal X at baseband. However when I listen back to this signal on my radio, demodulating with NFM it sounds very very distorted.

I have some questions about what I'm doing:

Is the above correct for generating an FM signal?
I'm presuming that the signal is being over-modulated and that's why I'm hearing distortion?
I've ran X through a low-pass filter at 6.25kHz, which I think would then give a signal at 12.5kHz deviation?
Is there anything else I could try to attempt to reduce the distortion heard on my radio?


Wed Nov 18, 2020 10:52 am
Profile Send private message
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 1 post ] 

Who is online

Users browsing this forum: No registered users and 1 guest

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
Powered by phpBB © phpBB Group.
Designed by Vjacheslav Trushkin for Free Forums/DivisionCore.