>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-discontinue
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 patc

>things in OK.

Thank you for your comments.
The off period is random, where it can be long or short. So multiplying b
0 will not work in this case.

>
>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 t

>it to make it work.

Yeah, I use several iterations of DFT filter to track its frequenc
incoming signal without memory (at this moment). Also, I am considering t
use Goertzel filter to track. Anyway, the operations are pretty similiar
though.

the problem is during DFT(Goertzel) filtering process in certai
iteration, the signal changes randomly, so that tracking process wil
generate incorrect or loose the output. It might lead to start over th
tracking process.

I thought windowing function to minimize phase discontinuity. however, du
to the random on and off, it is hard to apply windows on the signal
without having huge memory.

Thanks.
Timothy

>
>--
>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
>