"Insanely Exotic Modulation Tricks"
Radium
:
> On 11 Sep 2006 20:35:09 -0700, "Radium" <gluceg...@excite.com> wrote:
> >Hi:
> >Hypothetical situation: a PCM audio signal [24-bit and monoaural] is
> >transmitted through an analog 150 Khz AM carrier, an AM receiver on the
> >other end [tuned to 150 Khz] picks up the signal, and the reciever is
> >attached to a device that can recieve, process, and decode the PCM
> >audio back to analog and then send it to a loudspeaker. However -- in
> >this theoretical situation -- the environment is filled with magnetic
> >interference that affects all AM stations.
> Won't work. The data bit rate (for 44 KHz sampling) is 1.05 MHz, too
> much to put on a 150 KHz AM carrier, at least without insanely exotic
> modulation tricks.
> John
Just what are those "insanely exotic modulation tricks"?
lang...@ieee.org
> John Larkin wrote inhttp://groups.google.com/group/sci.electronics.basics/msg/3786a552954...
> :
>
> > On 11 Sep 2006 20:35:09 -0700, "Radium" <gluceg...@excite.com> wrote:
> > >Hi:
> > >Hypothetical situation: a PCM audio signal [24-bit and monoaural] is
> > >transmitted through an analog 150 Khz AM carrier, an AM receiver on the
> > >other end [tuned to 150 Khz] picks up the signal, and the reciever is
> > >attached to a device that can recieve, process, and decode the PCM
> > >audio back to analog and then send it to a loudspeaker. However -- in
> > >this theoretical situation -- the environment is filled with magnetic
> > >interference that affects all AM stations.
> > Won't work. The data bit rate (for 44 KHz sampling) is 1.05 MHz, too
> > much to put on a 150 KHz AM carrier, at least without insanely exotic
> > modulation tricks.
> > John
>
> Just what are those "insanely exotic modulation tricks"?
look up Shannon-Hartley and realize you would need a huge signal to
noise ratio ....
do you ever try to spend a few minutes reseaching before you ask one
of your numerous questions?
-Lasse
kell
> John Larkin wrote inhttp://groups.google.com/group/sci.electronics.basics/msg/3786a552954...
> :
>
> > >Hi:
> > >Hypothetical situation: a PCM audio signal [24-bit and monoaural] is
> > >transmitted through an analog 150 Khz AM carrier, an AM receiver on the
> > >other end [tuned to 150 Khz] picks up the signal, and the reciever is
> > >attached to a device that can recieve, process, and decode the PCM
> > >audio back to analog and then send it to a loudspeaker. However -- in
> > >this theoretical situation -- the environment is filled with magnetic
> > >interference that affects all AM stations.
> > Won't work. The data bit rate (for 44 KHz sampling) is 1.05 MHz, too
> > much to put on a 150 KHz AM carrier, at least without insanely exotic
> > modulation tricks.
> > John
>
> Just what are those "insanely exotic modulation tricks"?
What, you've never been to a strip club?
John Larkin
wrote:
Multiple-level quadrature modulation, "constellation modulation", is
most common for packing lots of bits per Hz of bandwidth. The more you
pack, the better the s/n ratio has to be. Read up on Shannon.
http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation
http://en.wikipedia.org/wiki/Constellation_diagram
John
Michael A. Terrell
>
> On Jul 20, 6:15 pm, Radium <gluceg...@gmail.com> wrote:
> > John Larkin wrote inhttp://groups.google.com/group/sci.electronics.basics/msg/3786a552954...
> >
>
> What, you've never been to a strip club?
Do you think he'd be wasting so much time posting garbage ,if he ever
got a close look at a woman that doesn't come with an air compresser?
--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
Radium
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote in
http://groups.google.com/group/sci.electronics.basics/msg/0c013cf5371da8dc?hl=en&
:
> On Fri, 20 Jul 2007 18:15:43 -0700, Radium <gluceg...@gmail.com>
> wrote:
> >John Larkin wrote in http://groups.google.com/group/sci.electronics.basics/msg/3786a5529547ea5a?hl=en& :
> >> On 11 Sep 2006 20:35:09 -0700, "Radium" <gluceg...@excite.com> wrote:
> >> >Hi:
> >> >Hypothetical situation: a PCM audio signal [24-bit and monaural] is
> >> >transmitted through an analog 150 KHz AM carrier, an AM receiver on the
> >> >other end [tuned to 150 KHz] picks up the signal, and the receiver is
> >> >attached to a device that can receive, process, and decode the PCM
> >> >audio back to analog and then send it to a loudspeaker. However -- in
> >> >this theoretical situation -- the environment is filled with magnetic
> >> >interference that affects all AM stations.
> >> Won't work. The data bit rate (for 44 KHz sampling) is 1.05 MHz, too
> >> much to put on a 150 KHz AM carrier, at least without insanely exotic
> >> modulation tricks.
> >Just what are those "insanely exotic modulation tricks"?
> Multiple-level quadrature modulation, "constellation modulation", is
> most common for packing lots of bits per Hz of bandwidth. The more you
> pack, the better the s/n ratio has to be. Read up on Shannon.
>
> http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation
>
> http://en.wikipedia.org/wiki/Constellation_diagram
In theory, could Quadrature Modulation and Constellation Modulation be
used to give dial-up modem connections around the same fast speeds
provided by Broadband cable modems?
John Larkin
wrote:
Dialup used to be 300, 1200, and finally 2400 baud using fairly simple
modems. Advanced modulation tricks (qam or multicarrier, with adaptive
equalization) were used to push dialup to 56K. That's about the limit
for dialup, because the signal bandwidth and s/n ratio are inherently
limited by the telephone company voice channel hardware.
DSL does better because it hiacks a fairly short pair of wires
directly from a substation to your house, and doesn't go through the
general telephone system.
Shannon's theorems establish rigid limits on what is possible, given a
communications channel of a given bandwidth and signal-to-noise ratio.
John
Radium
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> Dialup used to be 300, 1200, and finally 2400 baud using fairly simple
> modems. Advanced modulation tricks (qam or multicarrier, with adaptive
> equalization) were used to push dialup to 56K. That's about the limit
> for dialup, because the signal bandwidth and s/n ratio are inherently
> limited by the telephone company voice channel hardware.
>
> Shannon's theorems establish rigid limits on what is possible, given a
> communications channel of a given bandwidth and signal-to-noise ratio.
Could the telephone companies discard their present devices and build
new hardware that can provide frequencies ranging from 20 to 20,000 Hz
[instead of 300 to 3,000 Hz] and 120 dB [instead of 40 dB] dynamic
range? Or what that be not worth the time, energy, and money?
John Larkin
Radium
<jjlar...@highNOTlandTHIStechnologyPART.com> wrote:
> On Mon, 13 Aug 2007 23:42:24 -0000, Radium <gluceg...@gmail.com>
> wrote:
> >Could the telephone companies discard their present devices and build
> >new hardware that can provide frequencies ranging from 20 to 20,000 Hz
> >[instead of 300 to 3,000 Hz] and 120 dB [instead of 40 dB] dynamic
> >range? Or what that be not worth the time, energy, and money?
> Why would they do that?
Because the human auditory system perceives 20 to 20,000 Hz and has a
dynamic range of 120 dB.
Don Bowey
1187048544.9...@l22g2000prc.googlegroups.com, "Radium"
<gluc...@gmail.com> wrote:
Yes, but there is no realistic demand for that in message service. Radio
and TV stations often order 20 kHz channels for broadcast service.
Equiptment is available for that type (point-to-point, a.k.a. Private Line)
service.
For message service, including Cellular, some Common Carriers and private
networks use Low Bit-Rate coded channels to get more bang for the bucks.
For message use most people can't perceive a quality difference between
coding to 32 kbit/s vs 64 kbit/s.
You're pushing an old horse nobody wants.
Don Bowey
1187052933.9...@j4g2000prf.googlegroups.com, "Radium"
<gluc...@gmail.com> wrote:
Just because something can be done, doesn't mean it should be done. Who
would pay for the change-over?
James Beck
gluc...@gmail.com says...
and switch over to fibre or some kind of data channel?
Kind of a long road to take to get to the same destination.