Wow! until this I had not thought there was any bennfit to "out of passband notch".
Jim - W4YXU ----- Original Message ----- From: "Bob McGwier" <[EMAIL PROTECTED]> To: "Ray Andrews" <[EMAIL PROTECTED]> Cc: <flexradio@flex-radio.biz> Sent: Wednesday, July 11, 2007 1:41 PM Subject: Re: [Flexradio] Manual notch filter? > Here is the grand experiment we are going to try when we finally get to > calm down from the Flex5000 rush to finish. I have done enough > matlab/octave experimentation to expect it to work so long as we define > what it is we mean by work. > > Suppose you are listening to weak signal A. Strong signal B comes on > and its main power is well out of your passband but the splatter or > sidebands are in your passband and harms your ability to hear signal > A. The mathematical idea is that the portion of the signal B that is > in your passband is correlated with the "main" signal that is out of > your passband. 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. If > we get 20 dB reduction of the inband interference from an "out of band" > interferer, I will consider it a victory. Much more than that and I > will consider it to be a major league success. > > Bob > > Ray Andrews wrote: > > Guy, > > > > Of course, a notch filter could be coded to work anywhere in the range of > > the panadapter display. However, don't hold your breath waiting for it to > > do what you want. If the splatter is caused by an improperly adjusted > > transmitter somewhere else on the band, then the splatter consists of > > spurious signals that are within your desired pass band. Notching out the > > main signal will NOT reduce the spurious signals -- they have already been > > put there by the dirty transmitter. > > > > The only way that this type of notch filter would help is if the splatter is > > caused by overload in your receiver, either in the hardware or in the signal > > processing software. > > > > Sorry, > > > > 73, Ray, K9DUR > > > > > > _______________________________________________ > > 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/ > > > > > > > -- > Robert W. McGwier, Ph.D. > Center for Communications Research > 805 Bunn Drive > Princeton, NJ 08540 > (609)-924-4600 > (sig required by employer) > > > _______________________________________________ > 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/ > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.476 / Virus Database: 269.10.2/891 - Release Date: 7/8/2007 6:32 PM > _______________________________________________ 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/
