On 7/11/07, Bob McGwier <[EMAIL PROTECTED]> wrote: > > > ...It is strongly correlated and we should be able to > derive a "filter" that will predict a version of the signal that is IN > your passband. The property of the signal we will optimize on is to > reduce the energy of the interference to the best of our ability...
Lest we become prematurely enthusiastic...this is a ways off, at least as a routine procedure. Leaving aside the purely technical issues involved, we still need to be aware that *any* processing of this kind is going to involve significant latency. Like any kind of error correction, it depends on having a certain amount of leading data to chew on, with results that can be applied retrospectively to the output data stream. Based on what we know now, the necessary latency will be of roughly the same order as you get from robust digital voice on HF. *However* there is another approach which will yield far lower latency but at the expense of voice quality (although not intelligibility). This approach involves inserting a vocoding stage between the radio demod and the audio output. The result will be approximately cellphone-quality speech, but close to instantaneous response. The interference mitigation operates not on the signal but rather on the reduced vocoder coefficients. This is a lossy procedure, and there's no way to reconstruct what's thrown away in the compression process. But it reduces dramatically the search and computation space for both the inverse interferer filter and and cleaned-up signal of interest. If ever there were a reason to have all the DSP processing on a separate general-purpose CPU host, this kind of cleanup would surely have to rank near the top. 73 Frank AB2KT -------------- next part -------------- An HTML attachment was scrubbed... URL: http://mail.flex-radio.biz/pipermail/flexradio_flex-radio.biz/attachments/20070711/3c334d17/attachment.html _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
