On Wed, May 30, 2012 at 7:00 AM, George Allen <[email protected]>wrote:
> Looking at the specs for the 6000, and following the posts, I think that I > understand how it works. Is the following simplification correct? > > For the up to 70 MHZ band, as an example, there is an ADC that is sampling > the received data at a rate of at least 140MHZ within a Spectral Capture > Unit (using an ADC that's somewhat faster than the one on my Arduino), > corresponding to the Nyquist sampling frequency. By sampling at 2X the > highest frequency desired, the entire band can be recreated. > Yes. > > The sampled digital data is then further processed within a 6000 processor > to separate out "received slices" for the bands desired. > That is done in the FPGA. It does initial filtering and then decimation to create the smaller frequency "chunks" that have more dynamic range. This is now akin to what the receiver in a 5000/3000/1500 would have, except that there is no hardware. It is all software at this point. Later the output of the "slices" are processed in an additional DSP in the 6000 to implement all the other radio "functions" such as narrow filters, demodulation, interference management, etc. This part is akin to what is now done in a PC running PowerSDR. > This is a design that is somewhat hard to comprehend. I have not done any > signal processing in software since about 45 years ago when it was a > challenge to sample data at 8KHZ. > Welcome to the future. :-) Surprisingly, it is still the same old radio, just all the normal radio hardware of mixers, IF filters, BFOs, notch filters, etc., are entirely performed in software. Every "component" is precise and repeatable. No leakage, no extra shielding, no harmonics, no birdies, no stray capacitance pulling things off-frequency, no variations due to component tolerances, etc. -- Brian Lloyd, WB6RQN/J79BPL 3191 Western Dr. Cameron Park, CA 95682 [email protected] +1.767.617.1365 (Dominica) +1.916.877.5067 (USA) _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using beta versions of the software.
