What is the maximum bits-per-symbol possible using FSK on telephone devices?
in [DSP]
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From: glen herrmannsfeldt on 17 Dec 2009 01:42 steveu <steveu(a)coppice.org> wrote: >>On Wed, 16 Dec 2009 19:49:39 -0600, Green Xenon wrote: >>> What is the maximum amount of bits-per-symbol of FSK possible using a >>> telephone system [including the phone lines and any devices from start >>> to finish of the phone's signal chain]? >>Infinite, but you have to be patient. > Since telephone lines are heavily quantised by the PCM network, that's > only going to be true for very funky definitions of "symbol" or "FSK" Note that the symbol rate wasn't mentioned. Though I might say that 'symbol' only really applies for synchronous modulation methods. -- glen
From: Steve Pope on 17 Dec 2009 01:57 steveu <steveu(a)coppice.org> wrote: >>On Wed, 16 Dec 2009 19:49:39 -0600, Green Xenon wrote: >>> What is the maximum amount of bits-per-symbol of FSK possible using a >>> telephone system [including the phone lines and any devices from start >>> to finish of the phone's signal chain]? >>Infinite, but you have to be patient. >Since telephone lines are heavily quantised by the PCM network, that's >only going to be true for very funky definitions of "symbol" or "FSK" Not really. Symbol length = 24 hours Tone spacing = (1/86400) Hz 3 KHz bandwidth That comes to 2^28 tones = 28 bits per symbol. Steve
From: steveu on 17 Dec 2009 02:27 >steveu <steveu(a)coppice.org> wrote: > >>>On Wed, 16 Dec 2009 19:49:39 -0600, Green Xenon wrote: > >>>> What is the maximum amount of bits-per-symbol of FSK possible using a >>>> telephone system [including the phone lines and any devices from start >>>> to finish of the phone's signal chain]? > >>>Infinite, but you have to be patient. > >>Since telephone lines are heavily quantised by the PCM network, that's >>only going to be true for very funky definitions of "symbol" or "FSK" > >Not really. > >Symbol length = 24 hours >Tone spacing = (1/86400) Hz >3 KHz bandwidth > >That comes to 2^28 tones = 28 bits per symbol. Yeah, OK, that just requires an ovenised oscillator or rhubidium clock :-) Steve
From: Green Xenon on 17 Dec 2009 10:32 >Green Xenon <green_xenon1(a)yahoo.com> wrote: > >> [glen writes] > >>>All the FSK I know of are one bit/symbol. > >>Isn't MFSK [Multiple Frequency Shift Keying] a form of FSK that uses more >>than 1-bit-per-symbol? > >Does the M stand for Multiple or does it mean Minimal? M stands for multiple
From: glen herrmannsfeldt on 17 Dec 2009 15:10
Green Xenon <green_xenon1(a)yahoo.com> wrote: (snip) >>>Isn't MFSK [Multiple Frequency Shift Keying] a form of FSK >>>that uses more than 1-bit-per-symbol? (snip, someone wrote) >>Does the M stand for Multiple or does it mean Minimal? > M stands for multiple In that case I believe it is still one bit per symbol per FSK, though again I don't believe symbol is the right word in the FSK case. -- glen |