Stan 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, let's put it in the correct perspective. You have a LO of 1843/4 = 460.7 kHz (4 phases). Suppose that the sampling frequency of the sound card is 96 kHz. So, the zero frequency (DC) corresponds to 460.7 kHz and you have a tuning range of 48 kHz below and 48 kHz above this frequency, that is 460.7 - 48 = 412.7 and 460.7 + 48 = 508.7 So whatever signals are between 412.7 and 508.7 kHz are tunable with SDRadio. If you send the IF output of your receiver at 455 kHz to the quadrature mixer, then it falls inside the useable range. The max bandwidth of the signal is of course determined not by SDRadio, but instead by the IF circuitry of your radio. Actually what you will be doing is to use SDRadio as the last IF of a receiver. It can be used for this purpose, though really it is meant to be placed after a Direct Conversion mixer, where the selectable bandwidth, and the rejection of the unwanted sideband features can be fully exploited. 73 Alberto I2PHD ------------------------ 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/
