On Mon, Jul 14, 2008 at 11:41 PM, Steve Kallal <[EMAIL PROTECTED]> wrote: > Sorry, but I'm not sure I agree. By that definition many radios since the > 80s would be SDRs.
Not many radios from the 1980s are SDR, Affordable DSPs from the 1980s didn't have the bandwidth necessary to sample from the IF, (ideally after the 1st mixer on receive) rather than the AF. It wasn't until the late 1990s that cheap and powerful DSPs suitable were readily available, as far as I know. > My definition of an SDR is a radio that could be radically changed in > functionality by a software change. Perhaps the K3 fits that definition with > firmware changes. But does the K3 modulate or demodulate a signal using > analog or digital techniques. I am ignorant about the K3's architecture. Yes the K3 does modulate and demodulate the IF to produce a human readable audio / digital output. Personally I think a good rule of thumb is whether the radio could theoretically add a new operating mode with only software changes. In the case of the K3 this is true. For example Elecraft could (ignoring patent / technology licensing issues) add broadcast shortwave DRM support through a firmware update that the end-user could perform. > For example, early SSB rigs used a balanced modulator that nulled the > carrier. Then a filter selected LSB or USB. I think true SDR would do that > entirely in software. How does the K3 generate SSB? A "pure" SDR would have a ADC / DAC (optionally with power wideband amp for transmission) connected to antenna. In many cases a compromise with an analog RF front-end, typically consisting of 1 or 2 mixers for frequency translation and filtering. The closest to a pure SDR that I personally know of is the GNU Radio and certain USRP modules. As I understand it, some of the improvements in the Flex-radio 5000 are because of an improved analog RF front-end I believe. -Michael, VE3TIX _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
