+- 24KHz with 48KHz audio sampling At 11:26 AM 10/26/2005, you wrote:
>Let me ask the question in a different way. Assume we have a >receiver with the 455 khz IF. A common available xtal is 1843 khz >and 3686 khz. 1843/4 = 460.7 So if we mix the IF with the osc >we will get 5.7 khz output at the input the soundcard for SDRadio. > >Do we need to do anything ? How broad a range of input frequencies >will the soundcard pgm accept? > >Stan > > > > >--- In [email protected], Alberto I2PHD <[EMAIL PROTECTED]> wrote: > > > > Juan EA7FNJ wrote: > > > Hi guys, I have seen some schematics and I've got a question: > > > > > > At the input of SB, do I put a IF freq about 25KHz? If the SB is >about > > > 48KHz, I get the IF and they change into a two signals I & Q >about 25KHz. > > > > > > 455KHz - 1720 KHz (LO 4x) = 25KHz I & Q > > > > > > Is it correct? I hope I don't miss on this. > > > > Juan, > > basically it is correct, with some caveats. Your LO is 1720 >kHz, > > which divided by 4 (if you use a Johnson counter) gives 430 kHz. > > You must produce 4 phases at 430 kHz, spaced 90 degrees from each > > other, which are sent to a quadrature mixer, which will give as > > output the I and the Q components of the difference frequency, i.e. > > 455 - 430 = 25 kHz. Then you send these I and Q components to the > > sound card for digitization. The software will then bring that > > 25 kHz IF down to 0 Hz (DC), and extract the lower or the upper > > side band. > > > > 73 Alberto I2PHD > > > > > > > > > > >Yahoo! Groups Links > > > > Cecil Bayona KD5NWA www.qrpradio.com I fail to see why doing the same thing over and over and getting the same results every time is insanity: I've almost proved it isn't; only a few more tests now and I'm sure results will differ this time ... ------------------------ Yahoo! Groups Sponsor --------------------~--> Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/ELTolB/TM --------------------------------------------------------------------~-> Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> 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/
