As long as your front end and AD converter have enough dynamic range, there is really no need for AGC and simple amp somewhere in the frontend chain can increase the front end range enough .... I had thought of using a good audio compressor/limiter circuit after the QSD but when you start running the numbers you'll find you screw up the blocking dynamic range. Large signals in the 48K bandwidth will decrease the gain and render weak signals inaudible ... traditionally this is handled by a strong front end and a narrow IF filter to block out the strong station but that defeats our purpose here of grabbing a fairly wide chunk of the RF spectrum
Better to go with a 2 tier (Maybe 3) gain structure using software AGC and let the software filters get rid of the strong signal (Both are done better in software than hardware today) JR --- In [email protected], "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > > ZN414 IC > > 3 pin TO-92 and 8 pin DIP version. AM receiver on a chip. This is interesting because it has AGC built in. If used as a audio amp section after quadrature detection then some degree of AGC can be obtained in the receiver without allot of complexity. > > The specs mention that it is rated for use from 150 kHz to 3 MHz. Since there are no such things as tuned circuits in the chip I am confident that it may work all the way down into the audio range. Being the rating of 150 kHz is near to 96 kHz but derated dB wise. > > I have found no specs on the audio output responce and do not expect it will be flat across the spectrum. It should however pass some audio frequencies up to 96 kHz. One may not desire to use it if the specs are not correct for their application but I am sure some will try and it may suit their purposes. If you would like to have your SDR receiver double as a regular receiver with its own speaker then this simple chip will make that possible for AM. This then takes the complexity of circuity out of the design of receivers. Adding extra features in a simple manner. If used this way then the agc line may be sampled and used eslewhere in your scheme when used in SDR mode. > > > _____________________________________________________________________ > Call Anyone, Anytime, Anywhere in the World - FREE! > Free Internet calling from NetZero Voice > Visit http://www.netzerovoice.com today! > ------------------------ Yahoo! Groups Sponsor --------------------~--> Something is new at Yahoo! Groups. Check out the enhanced email design. http://us.click.yahoo.com/SISQkA/gOaOAA/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/
