What'd he say? Lol Scott AC8DE
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Mike Valentine Sent: Tuesday, May 29, 2012 9:27 PM To: Drax Felton Cc: [email protected] Subject: Re: [FlexEdge] Slices One could possibly do that, but there would be all sorts of LO settling time issues after a slew in frequency as the LO hopped around. One would need to blank all processing until the LO settled, post slew. And, the time-sharing aspect would hurt sensitivity as the total input power would be spread across multiple "dwell" frequencies of the LO. The receive sensitivity would be reduced by the number of slices being monitored because of having to time-share the LO and the antenna's contribution to each slice frequency. It's MUCH simpler to do what the Flex-6xxx does and spawn multiple CORDIC IQ down-converters in software to get to a better place. As long as the FPGA CORDIC processing can keep up, there is no downside to many simultaneous slices being processed concurrently. The total input power from the antenna to the ADC is not diluted while being digitized and all of the signals of interest are contained in the bit stream until processed out by the FPGA routines. Once the ADC performs its magic, only the downstream computational power limits what signals can be extracted from the antenna. So, when it comes to FPGA performance, --- size matters ;-0 And, that is all that matters. Best, Mike-W8MM On May 29, 2012, at 8:59 PM, Drax Felton wrote: > So couldn't the software rapidly vary the oscillator to give the appearance of monitoring more spectrum? > > > Sent from my iPhone > > On May 29, 2012, at 7:56 PM, Mike Valentine <[email protected]> wrote: > >> Because the Flex-5000/3000/1500 only digitize around the LO frequency applied to the quadrature sampling mixer and is limited to processing signals within a narrow range about that LO. >> >> The Flex-6XXX digitizes the entire spectrum from near DC to 77 MHz and can process any signal thus captured. >> >> Cheers, >> >> Mike-W8MM >> >> >> On May 29, 2012, at 5:58 PM, Drax Felton wrote: >> >>> >>> >>> >>> >>> So why can't the Flex 5000 and PowerSDR emulate the idea of >>> monitoring slices of multiple bands? >>> >>> >>> >>> >>> >>> _______________________________________________ >>> 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. >>> >> >> >> >> _______________________________________________ >> 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. > _______________________________________________ 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. _______________________________________________ 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.
