--- "Richard (Rick) Karlquist (N6RK)" <[EMAIL PROTECTED]> wrote:
> Related question: The softrock receiver has I and Q > outputs > to 2 audio inputs for image rejection. If I build a > hardware > image reject filter, can I get away with just using > I, which saves > an audio input, and halves the number of sound cards > needed. > > Any other way to accomplish this? Hardware vs. DSP. Seemingly, for those with a modern PC, DSP wins, because hardware is simpler, but bulkier, more labor intensive, and might be more expensive for a given level of results. I am assuming, of course, that you have a suitable PC. Of course, a bunch of passive parts should be cheaper than a modern PC. I have worked with on a SSB receiver with a polyphase phase shift network and you need 56 RC components for some 80 dB of opposite sideband suppression. Some may say that 60 dB (or 40 db) is enough, but certainly 80 dB sounds like a REAL radio with a good (Collins ?) mechanical filter. The hardware approach also requires some degree of component matching to achieve the expected results. For those without a powerful enough computer, it is the way to go. But using a computer, it is hard to justify the effort and expense of 56 x N components for N channels. I know of no software that does what you want, nowadays, but it does not mean it is not "doable", maybe because it has not been widely distributed, or no capable programmer has felt the need to work on it... Good luck, Jose, CO2JA __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
