The QSD SDR has provided very good receiver performance at a lower cost than conventional receivers and it has achieved the goal of making the modulator and demodulator a part of the digital signal processing, bridging the gap between IF DSP and AF DSP processors. But it still has one mixing process which is a potential source of intermodulation distortion.
The next logical step is to eliminate the QSD mixer and sample the RF spectrum directly at the antenna. This is the basis of 4th generation SDRs. The process is known as Direct Digital Sampling (DDS). DDS software defined radios sample the entire HF spectrum from a few kHz up to 55MHz or higher at once. To comply with the Nyquist theorem this requires very fast analog to digital converters which have only become available in the last few years. 73, Ron, K5HM <mailto:[email protected]> [email protected] <http://www.qrz.com/db/k5hm> www.qrz.com/db/k5hm Excelsior! From: BVARC [mailto:[email protected]] On Behalf Of Scott Royall via BVARC Sent: Sunday, August 30, 2015 2:35 PM To: 'BRAZOS VALLEY AMATEUR RADIO CLUB' <[email protected]> Cc: Scott Royall <[email protected]> Subject: Re: [BVARC] New Icom Rig -- IC 7300 What's the difference? From: BVARC [mailto:[email protected]] On Behalf Of Gary Sitton via BVARC Sent: Sunday, August 30, 2015 14:12 To: BRAZOS VALLEY AMATEUR RADIO CLUB <[email protected] <mailto:[email protected]> > Cc: Gary Sitton <[email protected] <mailto:[email protected]> > Subject: Re: [BVARC] New Icom Rig -- IC 7300 Ron: The Flex 5000 was the 1st DDC/DUC from Flex, but the 1000, 1500, and 3000 used QSD which is a cheaper direct sampling technology as have many other SDRs in the last 10 years or so. Gary On 8/30/2015 09:08, K5HM via BVARC wrote: ICOM is claiming that they are the first to offer direct sampling . I thought that most of the new Flex line already did that. Seems that all new rigs now claim they are SDR. Whatever that is. 73, Ron, K5HM [email protected] <mailto:[email protected]> www.qrz.com/db/k5hm <http://www.qrz.com/db/k5hm> Excelsior! From: BVARC [mailto:[email protected]] On Behalf Of Rick Hiller via BVARC Sent: Saturday, August 29, 2015 6:20 PM To: 'BRAZOS VALLEY AMATEUR RADIO CLUB' <mailto:[email protected]> <[email protected]> Cc: [email protected] <mailto:[email protected]> Subject: [BVARC] New Icom Rig -- IC 7300 EXTRA, EXTRA, READ ALL ABOUT IT.... ICOM IC-7300 SDR http://www.icomamerica.com/en/products/amateur/hf/7300/default.aspx _______________________________________________ BVARC mailing list [email protected] <mailto:[email protected]> http://mail.bvarc.org/mailman/listinfo/bvarc_bvarc.org
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