>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
>

Hi,

How do you track the frequencies?
If you use a fft-based method (looking for peaks),
I think it might be better if you leave the "off-parts"
in. The multiplies with zeros for the "off-parts"
will introduce spurious peaks, but you could
use an algorithm which "puts a question-mark" to all new
peak in a new STFT frame and just considers to track them
if they appear in more than one succesive STFT frame.

It really depends on:

1. What method are you using to track the frequencies of
the sinusoids?

2. What is the ratio between "on" and "off" parts?
How much of the signal is dropped?

Splicing the signals together doesn't seem to make too much
sense. But maybe I'm wrong...

gr.
Bjoern