Algorithm - detect carrier

[Ishira]

Hi,

I am trying to write a program which detects if a signal is modulated
or not; i.e whether there is a carrier or not.

Any suggestions would be greatly appreciated. Also, if you can direct
me to some tutorials/books which handles algorithms of this sort, it
would be great.

Thanks.
Ishira

[Mads G. Christensen]

Hi.

Ishira> Hi, I am trying to write a program which detects if a signal
Ishira> is modulated or not; i.e whether there is a carrier or not.

Ishira> Any suggestions would be greatly appreciated. Also, if you can
Ishira> direct me to some tutorials/books which handles algorithms of
Ishira> this sort, it would be great.

What kind of modulation are we talking about? If we are talking
amplitude modulation, then you may want to have a look at O. Besson
and P. Stoica "Nonlinear least-squares approach to frequency
estimation and detection for sinusoidal signals with arbitrary
envelope, Digital Signal Processing - A Review Journal, vol. 9, 1999.

--
/Mads (http://kom.auc.dk/~mgc)

[Andrew Paule]

Pull an FFT on the thing - carrier band should pop out nicely -
subtract it and the rest is noise and modulation - this is pretty well
documented in the FM case, and the AM case has been nicely commented on
by Mads

Andrew

Ishira wrote:

>Hi,
>
>I am trying to write a program which detects if a signal is modulated
>or not; i.e whether there is a carrier or not.
>
>Any suggestions would be greatly appreciated. Also, if you can direct
>me to some tutorials/books which handles algorithms of this sort, it
>would be great.
>
>Thanks.
>Ishira
>
>

[Ishira]

1. I know that the signal data can only be BB, Constant Carrier
Modulation(CCM), FSK or C_FSK.

So basically, I need to classify the data into one of these modulation
schemes.

2. After that I need to demodulate and then decode.


Thank you so much for your input. It has really got me thinking. I am
now really thirsty for more!

Ishira.








[email protected] (Mads G. Christensen) wrote in message news:<[email protected]>...
> Hi.
>
> Ishira> Hi, I am trying to write a program which detects if a signal
> Ishira> is modulated or not; i.e whether there is a carrier or not.
>
> Ishira> Any suggestions would be greatly appreciated. Also, if you can
> Ishira> direct me to some tutorials/books which handles algorithms of
> Ishira> this sort, it would be great.
>
> What kind of modulation are we talking about? If we are talking
> amplitude modulation, then you may want to have a look at O. Besson
> and P. Stoica "Nonlinear least-squares approach to frequency
> estimation and detection for sinusoidal signals with arbitrary
> envelope, Digital Signal Processing - A Review Journal, vol. 9, 1999.