On Thu, 15 Jan 2009 10:26:07 -0600, akachyan wrote:

> Hi,
>
> I have a sinusodal signals with fixed frequencies(multi-tone). But the
> signal is randomly on and off. What I did is that once the signal is
> off, I discarded the portion and, then, when the signal is on, I
> attached the signal afterward. So, now, the signal becomes phase
> discontinued, same frequency,though.
>
> My frequency tracking algorithm works with the original sinusoidal
> signals(without off). Not it cannot track the phase-discontinued signal
> properly.
> Is there any way to track the frequency of the signal?
>
> Thank you in advance.
> timothy

If the off period isn't too long, and if the phase is continuous even
with the thing shut off (i.e. if the carrier generation is always on,
it's just multiplied by 0 for a while), then you should be able to patch
things in OK.

If the phase just can't be expected to be right, you can still come up
with an algorithm that can use the prior frequency information, with
knowledge that the current phase will be random. Without even an
overview of your algorithm, I can't comment on what you may need to do to
it to make it work.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html