Re: [Flexradio] Flex 6000 Family Dynamic Range
Clay : The difference is more than made up in the the fact that the new AD operates at 245 MHz and the old AD is 200 kHz and you get huge processing gain in the downsample and filter process greatly increases the dynamic range. Bob On May 18, 2012 4:46 PM, Clay W7CE w...@curtiss.net wrote: Did anyone else notice that the receivers on the 6500 and 6700 use a 16-bit ADC rather than 24-bit like the 5000A? That reduces the dynamic range by up to 48 dB (same dynamic range as the 1500). That will probably be fine on HF, but I already have occasional problems with ADC saturation on 6M when locals (within 25 miles) running 1500 watts are transmitting in the 96 or 192kHz bandpass of my current frequency. Of course, I can eliminate the saturation by turning off my preamp, but then I can't hear the weak station I was trying to work. 73, Clay W7CE __**_ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/**mailman/listinfo/flexradio_**flex-radio.bizhttp://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/**flexradio%40flex-radio.biz/http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/ ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
Re: [Flexradio] Flex 6000 Family Dynamic Range
On Fri, May 18, 2012 at 1:45 PM, Clay W7CE w...@curtiss.net wrote: Did anyone else notice that the receivers on the 6500 and 6700 use a 16-bit ADC rather than 24-bit like the 5000A? That reduces the dynamic range by up to 48 dB (same dynamic range as the 1500). No. Learn about decimation. -- Brian Lloyd, WB6RQN/J79BPL 3191 Western Dr. Cameron Park, CA 95682 br...@lloyd.com +1.767.617.1365 (Dominica) +1.916.877.5067 (USA) ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
Re: [Flexradio] Flex 6000 Family Dynamic Range
Hi Bob, If it's OK with everyone, I'd like to count this as my oh duh moment for today (my target is no more than one per day). I wasn't thinking about decimation. However, assuming a bandwidth of 192 kHz and a sample rate of 245 MHz, doesn't that only give an extra 5 bits or so of effective resolution? That still leaves us 3 bits short of the 5000A ADC, which still means 18 dB less dynamic range. Maybe I missed it in the PDF file, but I didn't see a dynamic range spec. 73, Clay W7CE On 5/18/2012 3:44 PM, Robert McGwier wrote: Clay : The difference is more than made up in the the fact that the new AD operates at 245 MHz and the old AD is 200 kHz and you get huge processing gain in the downsample and filter process greatly increases the dynamic range. Bob On May 18, 2012 4:46 PM, Clay W7CE w...@curtiss.net mailto:w...@curtiss.net wrote: Did anyone else notice that the receivers on the 6500 and 6700 use a 16-bit ADC rather than 24-bit like the 5000A? That reduces the dynamic range by up to 48 dB (same dynamic range as the 1500). That will probably be fine on HF, but I already have occasional problems with ADC saturation on 6M when locals (within 25 miles) running 1500 watts are transmitting in the 96 or 192kHz bandpass of my current frequency. Of course, I can eliminate the saturation by turning off my preamp, but then I can't hear the weak station I was trying to work. 73, Clay W7CE ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz mailto:FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/ No virus found in this message. Checked by AVG - www.avg.com http://www.avg.com Version: 2012.0.2176 / Virus Database: 2425/5007 - Release Date: 05/18/12 ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
Re: [Flexradio] Flex 6000 Family Dynamic Range
Clay, Just in rough numbers, you get a 1/2-bit for every divide-by-two decimation you do. If you are looking at dynamic range in a 500Hz bandwidth (this is what we typically do). The math I generally use to get there is log(f1/f2)/log(2)/2. I just think this way as a programmer (do everything in base 2). So if you take log(245.76E6/500)/log(2)/2 you get 9.4 extra bits when added to the 16 gives you 25.5 bits (152.7dB dynamic range). This assumes all 16-bits of the ADC are good which is probably not a good assumption. I'd have to pull out the notes and look at the data sheet again, but this should give you a rough idea. Hopefully I haven't made an additional duh today myself! Bottom line -- there's plenty of dynamic range. Also, if you are interested, we are using Xilinx DSP48E1 blocks which use an 18x25 multiplier and so Xilinx tools generate the on-board DDS as a 25-bit DDS by default --- again to preserve the SFDR of the receiver. We could add extra bits, but 25 are fine for the same reason. Steve Stephen Hicks, N5AC, AAR6AM VP Engineering FlexRadio Systems™ 4616 W Howard Ln Ste 1-150 Austin, TX 78728 Phone: 512-535-4713 x205 Email: st...@flexradio.com Web: www.flexradio.com *Tune In Excitement™* PowerSDR™ is a trademark of FlexRadio Systems On Fri, May 18, 2012 at 6:33 PM, Clay W7CE w...@curtiss.net wrote: Hi Bob, If it's OK with everyone, I'd like to count this as my oh duh moment for today (my target is no more than one per day). I wasn't thinking about decimation. However, assuming a bandwidth of 192 kHz and a sample rate of 245 MHz, doesn't that only give an extra 5 bits or so of effective resolution? That still leaves us 3 bits short of the 5000A ADC, which still means 18 dB less dynamic range. Maybe I missed it in the PDF file, but I didn't see a dynamic range spec. 73, Clay W7CE On 5/18/2012 3:44 PM, Robert McGwier wrote: Clay : The difference is more than made up in the the fact that the new AD operates at 245 MHz and the old AD is 200 kHz and you get huge processing gain in the downsample and filter process greatly increases the dynamic range. Bob On May 18, 2012 4:46 PM, Clay W7CE w...@curtiss.net mailto: w...@curtiss.net wrote: Did anyone else notice that the receivers on the 6500 and 6700 use a 16-bit ADC rather than 24-bit like the 5000A? That reduces the dynamic range by up to 48 dB (same dynamic range as the 1500). That will probably be fine on HF, but I already have occasional problems with ADC saturation on 6M when locals (within 25 miles) running 1500 watts are transmitting in the 96 or 192kHz bandpass of my current frequency. Of course, I can eliminate the saturation by turning off my preamp, but then I can't hear the weak station I was trying to work. 73, Clay W7CE __**_ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz mailto:FlexRadio@flex-radio.**bizFlexRadio@flex-radio.biz http://mail.flex-radio.biz/**mailman/listinfo/flexradio_** flex-radio.bizhttp://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/**flexradio%40flex-radio.biz/http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/ No virus found in this message. Checked by AVG - www.avg.com http://www.avg.com Version: 2012.0.2176 / Virus Database: 2425/5007 - Release Date: 05/18/12 __**_ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/**mailman/listinfo/flexradio_**flex-radio.bizhttp://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/**flexradio%40flex-radio.biz/http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/ ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flexradio.com/ Homepage: http://www.flexradio.com/
