(based on my audio background) , I think up to 5.2 or 5.5 kHz is where the best bang for the buck is. My experiments with subband coding in the 90s (divide up 0to 6kHz spectrum with quadrature mirror filters) was that I only needed a couple of bits for 4.5 to 6k (plus some scaling bits which could probably just be turned into on/off 1 bit ) .
Another thing I notice now, at least in Australia- Most 3G Telstra-Telstra mobile phone calls are all now wideband (AMW-WB) (generally the network loading permits it). There is a noticeable quality improvement going from land line (3k) to mobile phone... glen On 9/03/2016 9:31 AM, David Rowe wrote: > Another intriguing possibility is add another few samples and do > wideband, but still low bit rate coding. For example a 6 kHz audio > bandwidth at a channel bit rate of 1000 bit/s, and a RF bandwidth of say > 500Hz (QSPK with tones spaced at Rs). > > It takes very few bits to represent the higher frequencies, as the ear > has a log(f) response. The extra cues may give us a performance advantage. > > Sort of "out of the box" thinking we can do with open source. AFAIK the > rest of the low bit rate would is constrained to 300-3300Hz type audio. > > - David > > On 09/03/16 08:27, glen english wrote: >> "The 4th freq frequency histogram has a mean of 3.2kHz." >> >> I think we need the high frequency support- it adds , i think , to the >> intelligibility in a high noise listening environment. Especially for >> younger ears. There is a significant intel difference between 2700 and >> 3300 Hz band limited speech. >> >> glen >> >> >> On 8/03/2016 12:42 PM, David Rowe wrote: >>> Hello Lists, >>> >>> I'm working on some new ideas for Codec 2. The aim is to get quality >>> similar to FreeDV 1600 (which uses Codec 2 at 1300 bit/s) at 700 bit/s. >>> >> >> ------------------------------------------------------------------------------ >> Transform Data into Opportunity. >> Accelerate data analysis in your applications with >> Intel Data Analytics Acceleration Library. >> Click to learn more. >> http://makebettercode.com/inteldaal-eval >> >> >> >> _______________________________________________ >> Freetel-codec2 mailing list >> Freetel-codec2@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/freetel-codec2 >> > ------------------------------------------------------------------------------ > Transform Data into Opportunity. > Accelerate data analysis in your applications with > Intel Data Analytics Acceleration Library. > Click to learn more. > http://makebettercode.com/inteldaal-eval > _______________________________________________ > Freetel-codec2 mailing list > Freetel-codec2@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > -- - Glen English RF Communications and Electronics Engineer CORTEX RF & Pacific Media Technologies Pty Ltd ABN 40 075 532 008 PO Box 5231 Lyneham ACT 2602, Australia. au mobile : +61 (0)418 975077 ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://makebettercode.com/inteldaal-eval _______________________________________________ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
