It's common knowledge that digital technology gives more telephone [4 Khz wide] channels than analog technology - for the same spectrum width. This even with the steep-sided filters and SSB technology. Since the input and output need to be in analog form, I find digital's claim very unintuitive -- almost doubting it. Can someone offer an intuitive explanation ? I guess a 4 HHz bandwidth telco signal contains a lot of redundancy which is not needed to convey the inteligence ? Speech can even be transmitted as a sequence of 'predetermined sylables' - what are they called again ? So it seems to me that the improvement over analog methods can't be acheived merely by 'modeming', which would only add entropy. But once it's in the digital format, standard compression [by removing redundancy] can make for more efficiency ? Thanks for any info, == Chris Glur.
How can digital be more spectrum efficient than analog ?
Started by ●October 27, 2006
Reply by ●October 27, 20062006-10-27
On Fri, 27 Oct 2006 10:29:06 -0500, no-top-post wrote:>It's common knowledge that digital technology gives more telephone >[4 Khz wide] channels than analog technology - for the same spectrum >width. This even with the steep-sided filters and SSB technology. > >Since the input and output need to be in analog form, I find >digital's claim very unintuitive -- almost doubting it. > >Can someone offer an intuitive explanation ? > >I guess a 4 HHz bandwidth telco signal contains a lot of >redundancy which is not needed to convey the inteligence ? > >Speech can even be transmitted as a sequence of 'predetermined >sylables' - what are they called again ? > >So it seems to me that the improvement over analog methods >can't be acheived merely by 'modeming', which would only add >entropy. But once it's in the digital format, standard compression >[by removing redundancy] can make for more efficiency ? > >Thanks for any info, > >== Chris Glur. >Lot of information is already on line on the topic; Goggle for it. See http://en.wikipedia.org/wiki/Audio_data_compression Should get you up to speed so you can search intelligently. ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =----
Reply by ●October 27, 20062006-10-27
On 10/27/06 8:29 AM, in article 1161962862.317275@work.isdsl.net, "no-top-post" <no-top-post> wrote:> It's common knowledge that digital technology gives more telephone > [4 Khz wide] channels than analog technology - for the same spectrum > width. This even with the steep-sided filters and SSB technology.I disagree with what you say is "common Knowledge." What is your reference for this? Digital transmission provides a much better grade channel WRT noise, but at the cost of bandwidth. Telecommunication systems put 24 SSB nominal 4 kHz circuits in 96 kHz. The D4 digital systems require a 1.544 Mbit/s channel for their 24 nominal 4 kHz channels.> > Since the input and output need to be in analog form, I find > digital's claim very unintuitive -- almost doubting it.Speaking for Digital for the moment, "Digital" has not claimed any such ridiculous thing.> > Can someone offer an intuitive explanation ? > > I guess a 4 HHz bandwidth telco signal contains a lot of > redundancy which is not needed to convey the inteligence ?I guess I wouldn't guess about important things; I'd do some study.> > Speech can even be transmitted as a sequence of 'predetermined > sylables' - what are they called again ? >What were they called the first time? What's the relevance to your main issues?> > So it seems to me that the improvement over analog methods > can't be acheived merely by 'modeming', which would only add > entropy. But once it's in the digital format, standard compression > [by removing redundancy] can make for more efficiency ? > > Thanks for any info, > > == Chris Glur. > >Don
Reply by ●October 27, 20062006-10-27
"default" <default@defaulter.net> wrote in message news:tid4k21t7pg0b212785poqek3ep603gs5b@4ax.com...> On Fri, 27 Oct 2006 10:29:06 -0500, no-top-post wrote: > >>It's common knowledge that digital technology gives more telephone >>[4 Khz wide] channels than analog technology - for the same spectrum >>width. This even with the steep-sided filters and SSB technology. >> >>Since the input and output need to be in analog form, I find >>digital's claim very unintuitive -- almost doubting it. >> >>Can someone offer an intuitive explanation ? >> >>I guess a 4 HHz bandwidth telco signal contains a lot of >>redundancy which is not needed to convey the inteligence ? >> >>Speech can even be transmitted as a sequence of 'predetermined >>sylables' - what are they called again ? >> >>So it seems to me that the improvement over analog methods >>can't be acheived merely by 'modeming', which would only add >>entropy. But once it's in the digital format, standard compression >>[by removing redundancy] can make for more efficiency ? >> >>Thanks for any info, >> >>== Chris Glur. >> > Lot of information is already on line on the topic; Goggle for it. > > See > http://en.wikipedia.org/wiki/Audio_data_compression > > Should get you up to speed so you can search intelligently.Compression is one. The type of multiplexing could be another. It appears that you're assuming the analog approach using frequency multiplexing where each channel uses up 4kHz of bandwidth. However, other multiplexing methods are available with a digital stream. Example: N channels of voice might be time domain multiplexed and silent passages not sent at all in favor of serving other channels, etc. etc. The possibilities are clear enough - I don't know how they do it.... One can well trade bandwidth for computing load and fidelity *up to a point*. More computing load (coding/decoding), more channels in the same bandwidth. Less fidelity, more channels in the same bandwidth. Fred
Reply by ●October 27, 20062006-10-27
"default" <default@defaulter.net> wrote in message news:tid4k21t7pg0b212785poqek3ep603gs5b@4ax.com...> On Fri, 27 Oct 2006 10:29:06 -0500, no-top-post wrote: > >>It's common knowledge that digital technology gives more telephone >>[4 Khz wide] channels than analog technology - for the same spectrum >>width. This even with the steep-sided filters and SSB technology. >> >>Since the input and output need to be in analog form, I find >>digital's claim very unintuitive -- almost doubting it. >> >>Can someone offer an intuitive explanation ? >> >>I guess a 4 HHz bandwidth telco signal contains a lot of >>redundancy which is not needed to convey the inteligence ? >> >>Speech can even be transmitted as a sequence of 'predetermined >>sylables' - what are they called again ? >> >>So it seems to me that the improvement over analog methods >>can't be acheived merely by 'modeming', which would only add >>entropy. But once it's in the digital format, standard compression >>[by removing redundancy] can make for more efficiency ? >> >>Thanks for any info, >> >>== Chris Glur. >> > Lot of information is already on line on the topic; Goggle for it. > > See > http://en.wikipedia.org/wiki/Audio_data_compression > > Should get you up to speed so you can search intelligently.Compression is one. The type of multiplexing could be another. It appears that you're assuming the analog approach using frequency multiplexing where each channel uses up 4kHz of bandwidth. However, other multiplexing methods are available with a digital stream. Example: N channels of voice might be time domain multiplexed and silent passages not sent at all in favor of serving other channels, etc. etc. The possibilities are clear enough - I don't know how they do it.... One can well trade bandwidth for computing load and fidelity *up to a point*. More computing load (coding/decoding), more channels in the same bandwidth. Less fidelity, more channels in the same bandwidth. Fred
Reply by ●October 27, 20062006-10-27
"default" <default@defaulter.net> wrote in message news:tid4k21t7pg0b212785poqek3ep603gs5b@4ax.com...> On Fri, 27 Oct 2006 10:29:06 -0500, no-top-post wrote: > >>It's common knowledge that digital technology gives more telephone >>[4 Khz wide] channels than analog technology - for the same spectrum >>width. This even with the steep-sided filters and SSB technology. >> >>Since the input and output need to be in analog form, I find >>digital's claim very unintuitive -- almost doubting it. >> >>Can someone offer an intuitive explanation ? >> >>I guess a 4 HHz bandwidth telco signal contains a lot of >>redundancy which is not needed to convey the inteligence ? >> >>Speech can even be transmitted as a sequence of 'predetermined >>sylables' - what are they called again ? >> >>So it seems to me that the improvement over analog methods >>can't be acheived merely by 'modeming', which would only add >>entropy. But once it's in the digital format, standard compression >>[by removing redundancy] can make for more efficiency ? >> >>Thanks for any info, >> >>== Chris Glur. >> > Lot of information is already on line on the topic; Goggle for it. > > See > http://en.wikipedia.org/wiki/Audio_data_compression > > Should get you up to speed so you can search intelligently.Compression is one. The type of multiplexing could be another. It appears that you're assuming the analog approach using frequency multiplexing where each channel uses up 4kHz of bandwidth. However, other multiplexing methods are available with a digital stream. Example: N channels of voice might be time domain multiplexed and silent passages not sent at all in favor of serving other channels, etc. etc. The possibilities are clear enough - I don't know how they do it.... One can well trade bandwidth for computing load and fidelity *up to a point*. More computing load (coding/decoding), more channels in the same bandwidth. Less fidelity, more channels in the same bandwidth. Fred
Reply by ●October 27, 20062006-10-27
"default" <default@defaulter.net> wrote in message news:tid4k21t7pg0b212785poqek3ep603gs5b@4ax.com...> On Fri, 27 Oct 2006 10:29:06 -0500, no-top-post wrote: > >>It's common knowledge that digital technology gives more telephone >>[4 Khz wide] channels than analog technology - for the same spectrum >>width. This even with the steep-sided filters and SSB technology. >> >>Since the input and output need to be in analog form, I find >>digital's claim very unintuitive -- almost doubting it. >> >>Can someone offer an intuitive explanation ? >> >>I guess a 4 HHz bandwidth telco signal contains a lot of >>redundancy which is not needed to convey the inteligence ? >> >>Speech can even be transmitted as a sequence of 'predetermined >>sylables' - what are they called again ? >> >>So it seems to me that the improvement over analog methods >>can't be acheived merely by 'modeming', which would only add >>entropy. But once it's in the digital format, standard compression >>[by removing redundancy] can make for more efficiency ? >> >>Thanks for any info, >> >>== Chris Glur. >> > Lot of information is already on line on the topic; Goggle for it. > > See > http://en.wikipedia.org/wiki/Audio_data_compression > > Should get you up to speed so you can search intelligently.Compression is one. The type of multiplexing could be another. It appears that you're assuming the analog approach using frequency multiplexing where each channel uses up 4kHz of bandwidth. However, other multiplexing methods are available with a digital stream. Example: N channels of voice might be time domain multiplexed and silent passages not sent at all in favor of serving other channels, etc. etc. The possibilities are clear enough - I don't know how they do it.... One can well trade bandwidth for computing load and fidelity *up to a point*. More computing load (coding/decoding), more channels in the same bandwidth. Less fidelity, more channels in the same bandwidth. Fred
Reply by ●October 27, 20062006-10-27
"default" <default@defaulter.net> wrote in message news:tid4k21t7pg0b212785poqek3ep603gs5b@4ax.com...> On Fri, 27 Oct 2006 10:29:06 -0500, no-top-post wrote: > >>It's common knowledge that digital technology gives more telephone >>[4 Khz wide] channels than analog technology - for the same spectrum >>width. This even with the steep-sided filters and SSB technology. >> >>Since the input and output need to be in analog form, I find >>digital's claim very unintuitive -- almost doubting it. >> >>Can someone offer an intuitive explanation ? >> >>I guess a 4 HHz bandwidth telco signal contains a lot of >>redundancy which is not needed to convey the inteligence ? >> >>Speech can even be transmitted as a sequence of 'predetermined >>sylables' - what are they called again ? >> >>So it seems to me that the improvement over analog methods >>can't be acheived merely by 'modeming', which would only add >>entropy. But once it's in the digital format, standard compression >>[by removing redundancy] can make for more efficiency ? >> >>Thanks for any info, >> >>== Chris Glur. >> > Lot of information is already on line on the topic; Goggle for it. > > See > http://en.wikipedia.org/wiki/Audio_data_compression > > Should get you up to speed so you can search intelligently.Compression is one. The type of multiplexing could be another. It appears that you're assuming the analog approach using frequency multiplexing where each channel uses up 4kHz of bandwidth. However, other multiplexing methods are available with a digital stream. Example: N channels of voice might be time domain multiplexed and silent passages not sent at all in favor of serving other channels, etc. etc. The possibilities are clear enough - I don't know how they do it.... One can well trade bandwidth for computing load and fidelity *up to a point*. More computing load (coding/decoding), more channels in the same bandwidth. Less fidelity, more channels in the same bandwidth. Fred
Reply by ●October 27, 20062006-10-27
"default" <default@defaulter.net> wrote in message news:tid4k21t7pg0b212785poqek3ep603gs5b@4ax.com...> On Fri, 27 Oct 2006 10:29:06 -0500, no-top-post wrote: > >>It's common knowledge that digital technology gives more telephone >>[4 Khz wide] channels than analog technology - for the same spectrum >>width. This even with the steep-sided filters and SSB technology. >> >>Since the input and output need to be in analog form, I find >>digital's claim very unintuitive -- almost doubting it. >> >>Can someone offer an intuitive explanation ? >> >>I guess a 4 HHz bandwidth telco signal contains a lot of >>redundancy which is not needed to convey the inteligence ? >> >>Speech can even be transmitted as a sequence of 'predetermined >>sylables' - what are they called again ? >> >>So it seems to me that the improvement over analog methods >>can't be acheived merely by 'modeming', which would only add >>entropy. But once it's in the digital format, standard compression >>[by removing redundancy] can make for more efficiency ? >> >>Thanks for any info, >> >>== Chris Glur. >> > Lot of information is already on line on the topic; Goggle for it. > > See > http://en.wikipedia.org/wiki/Audio_data_compression > > Should get you up to speed so you can search intelligently.Compression is one. The type of multiplexing could be another. It appears that you're assuming the analog approach using frequency multiplexing where each channel uses up 4kHz of bandwidth. However, other multiplexing methods are available with a digital stream. Example: N channels of voice might be time domain multiplexed and silent passages not sent at all in favor of serving other channels, etc. etc. The possibilities are clear enough - I don't know how they do it.... One can well trade bandwidth for computing load and fidelity *up to a point*. More computing load (coding/decoding), more channels in the same bandwidth. Less fidelity, more channels in the same bandwidth. Fred
Reply by ●October 27, 20062006-10-27
"default" <default@defaulter.net> wrote in message news:tid4k21t7pg0b212785poqek3ep603gs5b@4ax.com...> On Fri, 27 Oct 2006 10:29:06 -0500, no-top-post wrote: > >>It's common knowledge that digital technology gives more telephone >>[4 Khz wide] channels than analog technology - for the same spectrum >>width. This even with the steep-sided filters and SSB technology. >> >>Since the input and output need to be in analog form, I find >>digital's claim very unintuitive -- almost doubting it. >> >>Can someone offer an intuitive explanation ? >> >>I guess a 4 HHz bandwidth telco signal contains a lot of >>redundancy which is not needed to convey the inteligence ? >> >>Speech can even be transmitted as a sequence of 'predetermined >>sylables' - what are they called again ? >> >>So it seems to me that the improvement over analog methods >>can't be acheived merely by 'modeming', which would only add >>entropy. But once it's in the digital format, standard compression >>[by removing redundancy] can make for more efficiency ? >> >>Thanks for any info, >> >>== Chris Glur. >> > Lot of information is already on line on the topic; Goggle for it. > > See > http://en.wikipedia.org/wiki/Audio_data_compression > > Should get you up to speed so you can search intelligently.Compression is one. The type of multiplexing could be another. It appears that you're assuming the analog approach using frequency multiplexing where each channel uses up 4kHz of bandwidth. However, other multiplexing methods are available with a digital stream. Example: N channels of voice might be time domain multiplexed and silent passages not sent at all in favor of serving other channels, etc. etc. The possibilities are clear enough - I don't know how they do it.... One can well trade bandwidth for computing load and fidelity *up to a point*. More computing load (coding/decoding), more channels in the same bandwidth. Less fidelity, more channels in the same bandwidth. Fred
