Re: Using an FM-Carrier for the Y [Luminance] Signal -- how to relieve the bandwidth issue?
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Green Xenon [Radium]
http://groups.google.com/group/uk.tech.digital-tv/msg/e85e65d92a479a00 :
> "Green Xenon [Radium]" <gluceg...@excite.com> wrote in
messagenews:46f86fa7$0$9596$4c36...@roadrunner.com...
>
> > Couldn’t the video signal first be
> > converted to QAM, multiple-level
> > quadrature modulation, and/or
> > constellation modulation and then
> > transmitted on a FM radio carrier?
>
> > AFAIK, the
> > QAM/multiple-level-QM/constellation-modulation
> > version of the
> > video signal won’t require as much
> > bandwidth as the original video signal.
> > The original video signal is first converted
> > to bits and symbols and then
> > transmitted on an FM radio carrier.
> > To make the best use of bandwidth,
> > limit the baud to only
> > 1-symbol-per-second but pack as many
> > bits-per-symbol as feasible.
> Why?????
>
> Why make it use more bandwidth by
> introducing totally superfluous FM
> modulation??
I wish I could answer that question. It’s a matter of personal
preference. I’ve got this urge to get what I know I can’t have. FM video
is one of them. Hence, I want to do anything possible to transmit the
luminance component of video signals on FM without hogging excessive
bandwidth.
QAM/multiple-level-QM/constellation-modulation are examples of exotic
modulation techniques that allow you to transmit/receive the most amount
of information while using the least amount of bandwidth. To further
prevent excessive usage of bandwidth while maintaining signal
efficiency, the baud should be no more than 1-symbol-per-second while
the amounts of bits-per-symbol conveyed should be the most that is
physically and mathematically-possible.
Before being transmitted on the FM carrier, the luminance video signal
should be converted to QAM, multiple-level-QM, and/or
constellation-modulation. The
QAM/multiple-level-QM/constellation-modulation version of the video
signal won’t consume as much FM bandwidth as the original video signal.
If the original luma is transmitted on an FM carrier, the resulting
deviations in the frequency of the FM wave will be excessive. If the
QAM/multiple-level-QM/constellation-modulation equivalent of the luma is
transmitted, the resulting frequency-deviations will be significantly
smaller and hence use a lot less bandwidth.
I’ve got a neurological disorder which I would like to discuss briefly.
I am not trying to make excuses for any of my posts but I don’t want
readers to wrongly-assume that I troll/spam NGs just for attention. I am
really interested in the stuff I post about and wish that the readers
would not get upset at me.
I have a neurological disability called Asperger's Syndrome.
I would like to give you all some information about my disability. The
reason I am posting this message about Asperger's is to help avoid any
potential misunderstandings [though it's probably too late].
I have been diagnosed with Asperger's Syndrome (AS). AS is a
neurological condition that causes significant impairment in social
interactions. People with AS see the world differently and this can
often bring them in conflict with conventional ways of thinking. They
have difficulty in reading body language, and interpreting subtle cues.
In my situation, I have significant difficulty with natural
conversation, reading social cues, and maintaining eye contact. This can
lead to a great deal of misunderstanding about my intent or my behavior.
For example, I may not always know what to say in social situations, so
I may look away or may not say anything. I also may not always respond
quickly when asked direct questions, but if given time I am able express
my ideas.
On Usenet, the cyber-equivalent of my disability is probably noticed. I
do apologize profusely, for any inconvenience it causes.
Thank you very much in advance for your understanding, cooperation, and
assistance.
Regards,
Radium
Dave Platt
Green Xenon [Radium] <gluc...@excite.com> wrote:
>I wish I could answer that question. It’s a matter of personal
>preference.
When your preferences are at odds with physical reality, guess which
wins?
>QAM/multiple-level-QM/constellation-modulation are examples of exotic
>modulation techniques that allow you to transmit/receive the most amount
>of information while using the least amount of bandwidth. To further
>prevent excessive usage of bandwidth while maintaining signal
>efficiency, the baud should be no more than 1-symbol-per-second while
>the amounts of bits-per-symbol conveyed should be the most that is
>physically and mathematically-possible.
Mathematically, there's essentially no problem. All you need to do is
use a symbol representation which has enough discrete states to carry
the desired amount of information.
The problem here is "physically". Your proposal is very far out
beyond the point of physical realizability.
Video-grade luminance carries a lot of information. Just for grins,
let's say that it's the equivalent of a megabit per second - you can
get tolerable video at that bit rate using MPEG-2 or MPEG-4
compression of typical images. [An uncompressed/uncoded analog video
image requires a *lot* more bandwidth than this... maybe the
equivalent of 20-50 megabits per second?]
So, if you want only one symbol per second (one baud) to keep the
bandwidth down, you have to be able to transmit 1 megabit of
information in that one symbol. That requires that the symbol
representation include
1,000,000
2
different states. That is, the sender has to be able to choose from
among 2-to-the-millionth-power different voltages or RF levels (or QAM
or other constellation states), and the recipient needs to be able to
successfully distinguish between all of these states in order to
recover the megabit of information.
If you look at this in terms of the voltage being transmitted, it
means that the difference in voltage between any two adjacent states
must be large enough to be measured reliably. That would mean that
the _maximum_ voltage needs to be 2-to-the-millionth times higher.
If we want to ease the problem somewhat, we could use a QAM encoding,
with 2^1000 different amplitudes and 2^1000 different phases.
Even if you do that, the signal resolution you need is incredibly far
beyond what's physically possible. If you ran the entire system in a
bath of liquid helium (to keep the thermal noise level of all the
components down to a minimum), and you set the minimum voltage
difference between two states to something just barely above the
remaining thermal noise level ...
... then the maximum voltage level produced by your transmitter will
still be billions of billions of billions of billions times (billions
*of* billions, not billions *and* billions) higher. It wouldn't just
burn out the transmitter... it would (if physically realizable) blow
everything in the solar system into incandescent plasma as soon as you
turned it on.
>If the original luma is transmitted on an FM carrier, the resulting
>deviations in the frequency of the FM wave will be excessive. If the
>QAM/multiple-level-QM/constellation-modulation equivalent of the luma is
>transmitted, the resulting frequency-deviations will be significantly
>smaller and hence use a lot less bandwidth.
Don't bet on it. Remember that the abrupt transitions between QAM
states create a sudden discontinuity in the signal... which introduces
higher-frequency components or sidebands in your encoded luma signal.
These luma sidebands, once FM-modulated onto the carrier, will cause
RF sidebands out quite some distance. That's one of the gotchas of
FM... it creates sidebands which appear *further* away from the
carrier frequency than the maximum carrier deviation!
In short, there's no free lunch. For *any* given baseband signal
(straight, QAM-encoded, or whatever), an FM-modulated carrier will
*always* produce sidebands which go out as broadly as an AM carrier or
further, and will *never* take up less spectrum than an AM carrier
with the same baseband information.
In other words, no matter what coding tricks you can think up to try
to make FM video narrower than AM, you'll lose, because you can apply
the same coding tricks to the input of an AM modulator.
--
Dave Platt <dpl...@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
Green Xenon [Radium]
http://groups.google.com/group/uk.tech.digital-tv/msg/a9872fef8b5bfab4 :
> In article <46faa23a$0$7443$4c368...@roadrunner.com>,
Can’t the maximum voltage be set to be low enough not to cause any
damage/injury to anyone/anything?
Also, couldn’t the temporal and spatial frequencies of the luminance
signal be downshifted prior to QM conversion so that not so many bits
are required?
It’s possible to downshift the frequencies of an audio signal without
low-pass-filtering or changing the speed at which it is played-back.
Couldn’t the equivalent be done with the temporal and spatial
frequencies of a luminance signal?
> >If the original luma is transmitted on an FM carrier, the resulting
> >deviations in the frequency of the FM wave will be excessive. If the
> >QAM/multiple-level-QM/constellation-modulation
> >equivalent of the luma is
> >transmitted, the resulting frequency-deviations will be significantly
> >smaller and hence use a lot less bandwidth.
> Don't bet on it. Remember that the abrupt transitions between QAM
> states create a sudden discontinuity in the signal... which introduces
> higher-frequency components or sidebands in your encoded luma signal.
> These luma sidebands, once FM-modulated onto the carrier, will cause
> RF sidebands out quite some distance. That's one of the gotchas of
> FM... it creates sidebands which appear *further* away from the
> carrier frequency than the maximum carrier deviation!
>
> In short, there's no free lunch. For *any* given baseband signal
> (straight, QAM-encoded, or whatever), an FM-modulated carrier will
> *always* produce sidebands which go out as broadly as an AM carrier or
> further, and will *never* take up less spectrum than an AM carrier
> with the same baseband information.
>
> In other words, no matter what coding tricks you can think up to try
> to make FM video narrower than AM, you'll lose, because you can apply
> the same coding tricks to the input of an AM modulator.
Is there any thing that could be done to the QM signal so that the
resulting FM sidebands won’t be excessive?
In an FM carrier, the neutral frequency results when there is no
modulation signal. The FM carrier changes according to the modulator. If
the modulator voltage it positive, the FM carrier’s frequency increases.
When the modulator voltage becomes negative, the carrier’s frequency
decreases. On a graph of the modulator signal, the x-axis is where the
voltage is neutral. Above the x-axis, the voltage is positive. Below the
x-axis, the voltage is negative. The further from the x-axis the voltage
goes, the more broad the sidebands will be.
To prevent the sidebands from getting too broad, the QM signal needs to
have all to voltages shifted closer to the x-axis. This means the device
receiving the QM signals on the other end needs to be more sensitive to
differences in voltages.
Thus it would help if the physical voltage difference between what is
interpreted as 1 or 0 be much smaller. The smaller the change in
voltage, the less extreme the resulting FM sidebands.
Dave Platt
Green Xenon [Radium] <gluc...@excite.com> wrote:
>Can't the maximum voltage be set to be low enough not to cause any
>damage/injury to anyone/anything?
Not if you want to actually be able to use the signal. That was my
point about "liquid helium". If you reduce the upper voltage enough
to be physically realizable, then the smallest voltage difference
you'd have to be able to distinguish is *far* less than the
inescapable amount of noise in the system, even at extremely cold
temperatures where thermal noise is minimized.
>Also, couldn’t the temporal and spatial frequencies of the luminance
>signal be downshifted prior to QM conversion so that not so many bits
>are required?
Not enough to matter, by a factor of zillions to one.
>It’s possible to downshift the frequencies of an audio signal without
>low-pass-filtering or changing the speed at which it is played-back.
>Couldn’t the equivalent be done with the temporal and spatial
>frequencies of a luminance signal?
Once again, no, not enough to matter. If it was only a matter of 2:1
or 10:1, you might be able to do it. The one-baud scheme you propose
is off by a factor of 1,000,000,000,000,...,000 to 1 or so (*lots* of
zeros in there).
Go do as I said, and google "Shannon Limit". To sum it up: there's a
hard limit on the amount of information that you can send through a
communication channel which has (a) a finite bandwidth, and (2) a
finite signal-to-noise ratio.
Your goal of trying to pack video-grade information into small gaps in
the MW spectrum goes far beyond the Shannon limit.
>Is there any thing that could be done to the QM signal so that the
>resulting FM sidebands won’t be excessive?
>
>In an FM carrier, the neutral frequency results when there is no
>modulation signal. The FM carrier changes according to the modulator. If
>the modulator voltage it positive, the FM carrier’s frequency increases.
>When the modulator voltage becomes negative, the carrier’s frequency
>decreases. On a graph of the modulator signal, the x-axis is where the
>voltage is neutral. Above the x-axis, the voltage is positive. Below the
>x-axis, the voltage is negative. The further from the x-axis the voltage
>goes, the more broad the sidebands will be.
>
>To prevent the sidebands from getting too broad, the QM signal needs to
>have all to voltages shifted closer to the x-axis. This means the device
>receiving the QM signals on the other end needs to be more sensitive to
>differences in voltages.
>
>Thus it would help if the physical voltage difference between what is
>interpreted as 1 or 0 be much smaller. The smaller the change in
>voltage, the less extreme the resulting FM sidebands.
Your understanding of FM modulation is incomplete, and it is leading
you astray. You're only looking at half of the picture. You need to
go back and hit the books again so that you understand the whole
situation.
Yes, it's true that the instantaneous carrier deviation depends only
on the amplitude of the modulation signal. However, that's only part
of the picture. Sidebands are created out *beyond* the maximum
carrier deviation frequency... and they are created at frequencies
which are at offset-multiples of the modulating frequency.
You *cannot* narrow an FM signal down to a width less than the
modulating frequency. If you want to carry (for example) an audio
signal with 20,000 Hz of audio bandwidth, then the modulated FM signal
will always have sidebands out as far as 20,000 Hz on either side of
the nominal carrier frequency. This is true NO MATTER HOW SMALL the
amplitude of the modulating signal, as long as there's any signal at
all.
If you FM-modulate a carrier with a very low-level 20 kHz tone, you
might be causing only 1 kHz of carrier deviation... but there will
still be sidebands 20 kHz above and below the nominal carrier
frequency. That may seem strange and counterintuitive, but it's how
the math works out, and how measurements confirm it works.
Green Xenon [Radium]
http://groups.google.com/group/uk.tech.digital-tv/msg/118b30e3f36c8b05 :
> In article <46fc4458$0$16496$4c368...@roadrunner.com>,
> Green Xenon [Radium] <gluceg...@excite.com> wrote:
> >It’s possible to downshift the frequencies of an audio signal without
> >low-pass-filtering or changing the speed at which it is played-back.
> >Couldn’t the equivalent be done with the temporal and spatial
> >frequencies of a luminance signal?
>
> Once again, no, not enough to matter. If it was only a matter of 2:1
> or 10:1, you might be able to do it. The one-baud scheme you propose
> is off by a factor of 1,000,000,000,000,...,000 to 1 or so (*lots* of
> zeros in there).
Would 300:1 work?
300 Hz is the minimum frequency used by telephones and ULF
[Ultra-Low-Frequency] radios.
ULF radio = frequencies at least 300 Hz but no more than 3,000 Hz.
> Go do as I said, and google "Shannon Limit". To sum it up: there's a
> hard limit on the amount of information that you can send through a
> communication channel which has (a) a finite bandwidth, and (2) a
> finite signal-to-noise ratio.
>
> Your goal of trying to pack video-grade information into small gaps in
> the MW spectrum goes far beyond the Shannon limit.
The ULF is even lower-frequency than MW. If a baud of
20-symbols-per-second but 300 bits-per-symbol is used, can the luminance
signal have its temporal and spatial frequencies downshifted
sufficiently so that it can be on a ULF-frequency FM carrier? Will this
work even if the FM carrier’s center-frequency is 300 Hz?
So there is no way to decrease how far the sidebands will go?
Dave Platt
Green Xenon [Radium] <gluc...@excite.com> wrote:
>Would 300:1 work?
Not for video, no.
>The ULF is even lower-frequency than MW. If a baud of
>20-symbols-per-second but 300 bits-per-symbol is used, can the luminance
>signal have its temporal and spatial frequencies downshifted
>sufficiently so that it can be on a ULF-frequency FM carrier? Will this
>work even if the FM carrier’s center-frequency is 300 Hz?
No. No. And, no. You cannot possibly do this... for several reasons.
For one thing, trying to convey 300 bits of information per symbol is
still grossly optimistic. If you take a look at real-world modulation
systems (QAM64 and so forth) you'll find that they send much less
information per symbol... I don't have the best numbers available off
of the top of my head, but I'd be surprised if there's a system in
practical use which tries to send more than 16 bits per symbol. The
amount of noise on real-world communcation channels makes it
impractical-to-impossible to go much beyond that... and you are
proposing something *far* beyond that. Trust me - the laws of physics
in this universe won't permit you to do it.
For another thing, even if you *could* pack that much information into
a symbol, you'd still be capable of sending only 6000 bits per second.
That's far too little for anything resembling real video at real
resolutions... you couldn't even send one frame per second at that
rate.
For a third thing, the frequency content of a video luminance signal
starts just above DC, and goes up from there (to several MHz with
standard NTSC video). There really isn't any room for you to shift
the frequencies downwards by a useful amount... if you try, you end up
trying to shift real information down past DC. Either you lose it (if
you filter before shifting) or you *try* to shift it down past DC into
negative frequencies, and it aliases right back up into your passband
and distorts the rest of the signal.
To sum it up - what you're trying to do is fundamentally impossible.
It doesn't matter how you shift the luminance signal's frequencies
around. It doesn't matter how you modulate it. It doesn't matter
what tricks you play. You just don't have enough bandwidth available.
"You can't fool Mother Nature."
>So there is no way to decrease how far the sidebands will go?
With FM? Nope, not in the way you're hoping. Modulate a carrier Fc
with a frequency Fm, and the first sidebands will be at Fc+Fm and
Fc-Fm, just as would be true with AM. That's the narrowest you can
get.
Steven
Richard Crowley
> No. No. And, no. You cannot possibly do this... for several reasons.
>
> For one thing, trying to convey 300 bits of information per symbol is
> still grossly optimistic. If you take a look at real-world modulation
> systems (QAM64 and so forth) you'll find that they send much less
> information per symbol... I don't have the best numbers available off
> of the top of my head, but I'd be surprised if there's a system in
> practical use which tries to send more than 16 bits per symbol. The
> amount of noise on real-world communcation channels makes it
> impractical-to-impossible to go much beyond that... and you are
> proposing something *far* beyond that. Trust me - the laws of physics
> in this universe won't permit you to do it.
Perhaps "Radium" should ask his questions over there in
that other universe where *his* laws of physics apply.
Sjouke Burry
> In article <46fc71d2$0$24285$4c36...@roadrunner.com>,
> Green Xenon [Radium] <gluc...@excite.com> wrote:
>
>> Would 300:1 work?
>
> Not for video, no.
>
>> The ULF is even lower-frequency than MW. If a baud of
>> 20-symbols-per-second but 300 bits-per-symbol is used, can the luminance
>> signal have its temporal and spatial frequencies downshifted
>> sufficiently so that it can be on a ULF-frequency FM carrier? Will this
>> work even if the FM carrier’s center-frequency is 300 Hz?
>
> No. No. And, no. You cannot possibly do this... for several reasons.
>
As a known troll on many newsgroup he can do anything.
Eve hide under a bridge.
tonsofpcs
transmit video luma would be to take it, and create a digital system
that has a very large number of discrete states, so large that the
lines between them seem to blur, and transmit it at a very high
frequency (or more, maybe even an ultra high frequency), with a large
number of bits per symbol (8 seems like a good number) but a very high
temporal resolution. You could even modulate a color subcarrier on
and add in chroma information on two axis, lets call them I and Q.
This will create a situation where the receiver will be receiving the
data with interference, but since you are only sending a small amount
of data at each temporal interval, any interference's effect within a
decent area will be negligible and the viewer's eye's will compensate.
On second thought, analog video is so much simpler (and exactly the
same, except it lacks discrete levels).
--
A confused Eric, wondering why you're trying to do this....
Michael A. Terrell
>
> A confused Eric, wondering why you're trying to do this....
He isn't trying to do anything, other than troll for the gullible. :(
--
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
Green Xenon [Radium]
http://groups.google.com/group/uk.tech.digital-tv/msg/5d3083e46aff377a :
> A confused Eric, wondering why you're trying to do this....
Well, my goal was to somehow receive QM video signal on a
frequency-modulated ULF [radio-frequency between 300 and 3,000 KHz]
carrier -- in which the QM uses only 1 baud but shoves as many
bits-per-symbol mathematically possible while setting the maximum
voltage of the discrete states low enough not to cause any harm to
anyone or anything [including the equipment itself] -- and with as many
discrete states [between the highest and lowest voltage] as
mathematically-possible. Unfortunately, reality does not want me doing
this and reality always has the last word as to what does and what
doesn’t occur.
Anyways, my next question. Is it possible to split the symbol of a 1
baud, 8-bit-per-symbol signal into 8 bits? I.e. in this case, a single
symbol would be split into 8 different parts each carrying one of the
bits. Is this possible? If so, would this be of any assistance to me?
Richard Crowley
> Anyways, my next question. Is it possible to split the symbol of a 1
> baud, 8-bit-per-symbol signal into 8 bits? I.e. in this case, a single
> symbol would be split into 8 different parts each carrying one of the
> bits. Is this possible? If so, would this be of any assistance to me?
Sure it is possible. It won't be of any assistance to you (or to
anyone else since you can't put 8 pounds in a 1-pound sack.
Bandwidth is bandwidth, no matter how you slice it. Do you
really think that nobody has thought of various methods of
transmitting video over low-bandwidth paths? If so, you need
to study not only science and engineering but the HISTORY
of science and engineering.
Green Xenon [Radium]
http://groups.google.com/group/uk.tech.digital-tv/msg/88f1401cb2a43810 :
There are 8-bits-per-symbol, only 1 baud. The symbol is split into 8
parts. Each part is 1-bit.
How is this “putting 8 pounds in a 1-pound sack?”
It’s more like “putting 1 pound in a 1-pound sack”
Dave Platt
Green Xenon [Radium] <gluc...@excite.com> wrote:
> > Sure it is possible. It won't be of any assistance to you (or to
> > anyone else since you can't put 8 pounds in a 1-pound sack.
> > Bandwidth is bandwidth, no matter how you slice it. Do you
> > really think that nobody has thought of various methods of
> > transmitting video over low-bandwidth paths? If so, you need
> > to study not only science and engineering but the HISTORY
> > of science and engineering.
>
>There are 8-bits-per-symbol, only 1 baud. The symbol is split into 8
>parts. Each part is 1-bit.
>
>How is this “putting 8 pounds in a 1-pound sack?”
>
>It’s more like “putting 1 pound in a 1-pound sack”
You are using the word "split" without defining what you are meaning,
and I think you may be using the word "bit" in two different ways (as
in "a single binary digit's worth of information" and "a part")...
maybe I'm wrong about the latter.
Sure, you can carry 8 bits of information per symbol, at a rate of one
baud. That's an information rate of 8 bits per second, which isn't a
terribly useful amount of information.
What I *think* you are saying is something along the lines of
"If there's no way to carry N bits of information per symbol (where
N is a large number) at a rate of 1 symbol per second, in a
specified bandwidth, over a channel having a certain amount of
dynamic range / signal-to-noise ratio available, then I'd
like to somehow divide each symbol into eight sub-symbols which
each carry N/8 of the information, but which still make up only one
symbol per second. My hope is that these eight sub-symbols could
be easier to transmit, somehow, than a single symbol carrying N
bits, and that I could thus transmit them more easily but without
using any more bandwidth. Can I do that?"
If that's what you're asking, the answer is "no".
Once you hit the theoretical information limit of the communication
channel (which is set by the bandwidth you use and by the amount of
noise on the channel) you can't do any better than that. No matter
how you modulate (changing the baud rate, the amount of information
per symbol, etc.) you can't do better than this.
And, as we've been trying to make clear, your goal is quite far beyond
the theoretical limit. You just can't get there. You're trying to
put all of Lake Erie in a water-glass.
Let it go, Radium.
Green Xenon [Radium]
http://groups.google.com/group/uk.tech.digital-tv/msg/872fdf9b0c765bd0 :
> In article <46fefb70$0$7493$4c368...@roadrunner.com>,
Within physical-possibility, what is the largest amount of
bits-per-symbol [assuming a baud-rate of only 1-bit-per-symbol] that can
be reached without the highest-voltage causing any clipping, generating
any temperatures above 70 Fahrenheit, resulting in any harm to
anyone/anything [including the equipment itself], or shortening the life
of the equipment and without the lowest-voltage being lost in the noise?
What is the maximum-possible amount of discrete levels between the
highest and lowest voltage in such a signal?
An 8-bit signal can have a maximum of 256 different voltage levels
between the highest and lowest voltage. Right? Go too high and the
signal clips, go too low and the signal will not be recognized.
Roderick Stewart
wrote:
> > And, as we've been trying to make clear, your goal is quite far beyond
> > the theoretical limit. You just can't get there. You're trying to
> > put all of Lake Erie in a water-glass.
> >
> > Let it go, Radium.
>
> Within physical-possibility, what is the largest amount of
> bits-per-symbol [assuming a baud-rate of only 1-bit-per-symbol] that can
> be reached without the highest-voltage causing any clipping, generating
> any temperatures above 70 Fahrenheit, resulting in any harm to
> anyone/anything [including the equipment itself], or shortening the life
> of the equipment and without the lowest-voltage being lost in the noise?
> What is the maximum-possible amount of discrete levels between the
> highest and lowest voltage in such a signal?
>
> An 8-bit signal can have a maximum of 256 different voltage levels
> between the highest and lowest voltage. Right? Go too high and the
> signal clips, go too low and the signal will not be recognized.
I tell you what. Why don't you build one of these magic modulators, show us
that it works, and then we'll believe you.
If it does, I might be encouraged to have a go at making that machine I
invented at the age of about seven, even though my dad told me it wouldn't
work. My plan was to use an electric motor to turn a dynamo, which would
generate electricity, which would then be used to power the electric motor.
After it had been patiently explained to me that the amount of electricity
generated would not be enough to power the motor, my next idea was to
interpose some gears or pulleys so that the motor would turn the generator
a little faster, thereby generating more electricity. My understanding of
the physical world had some way to go, but we all have to start somewhere.
Rod.
Dave Platt
Green Xenon [Radium] <gluc...@excite.com> wrote:
>Within physical-possibility, what is the largest amount of
>bits-per-symbol [assuming a baud-rate of only 1-bit-per-symbol]
You just made a meaningless statement. Baud rate is measured in
symbols per second, not bits per symbol. I assume that you meant to
say "assuming a baud-rate of one symbol per second."
> that can
>be reached without the highest-voltage causing any clipping, generating
>any temperatures above 70 Fahrenheit, resulting in any harm to
>anyone/anything [including the equipment itself], or shortening the life
>of the equipment and without the lowest-voltage being lost in the noise?
>What is the maximum-possible amount of discrete levels between the
>highest and lowest voltage in such a signal?
And, another important constraint for actual usability is this: you
have to make sure that the minimum-detectable difference between two
different symbol levels can be detected reliably and accurately at
_all_ levels. In the language of analog-to-digital converts this is
referred to as "linearity" and "no missing codes".
[As a counterexample: the human hearing system can hear down to 0 dBa
or so... a sound level which is just barely above the noise created by
the random collision of air molecules with the eardrum. And, we can
hear sounds up to around 120 decibels above that, before damage starts
to result. That's a pretty wide dynamic range. However, it's not
linear... if we're listening to a loud sound (say, at 110 dB or so),
small sounds are completely lost... you can't hear somebody whispering
10 feet away when you're listening to a rock concert.]
>An 8-bit signal can have a maximum of 256 different voltage levels
>between the highest and lowest voltage. Right? Go too high and the
>signal clips, go too low and the signal will not be recognized.
Right.
At audio-quality sampling rates (say, 50,000 baud) you can buy
converters that are linear down to around 22 bits, I think...
marketers call them "24-bit" converters but they aren't actually
linear down to those levels. At instrumentation rates like 1 baud (1
sample per second), with filtering and averaging being applied to
eliminate the noise, you can do rather better.
I don't know quite what the state-of-the-art is for measuring signals
at such low baud rates as you are referring to. I'd guess that it's
somewhere in the range of 28-30 bits.
30 bits is roughly a billion-to-one ratio between the smallest signal
and the largest. Crudely put, it would mean that you might have a
circuit which has to handle voltages of up to 1000 volts, and has to
be able to generate, and then measure voltage differences of a
*millionth* of a volt, at all of these levels. That's going to be
technologically difficult, to say the least.
The *theoretical* limit is somewhat higher than this, but not enough
to help you achieve what you wish. It'll be limited at the low end by
the thermal noise level (a 50-ohm resistance at room temperature
generates -174 dBm of noise over a 1 Hz bandwidth) and at the high end
by whatever voltage you think your equipment can handle without
damage.
Even being extremely generous, and saying 32 bits of linear resolution
(and thus reliable data) per symbol, you aren't going to get video
across it. 32 bits per second is somewhere between "fast Morse code"
and "old Teletype teleprinter or ticker-tape" bandwidth.
Note that this is the generation and measurement limit and assumes an
interference-free communication link (e.g. a well-shielded cable), and
is *not* what you can get away with in a real-world radio
transmission! The background noise level on LF radio frequencies is
higher than this, due to both manmade and atmospheric electrical
noise.
As another poster has pointed out, there's a damned good reason why
nobody uses very-low-baud-rate modulations to send large amounts of
high-speed data over a narrow-bandwidth channel, despite a century or
more of research and study and competition in the fields of radio and
electronic communication. It just doesn't work, and the reasons why
it doesn't are well understood by those who practice in the field.
Green Xenon [Radium]
http://groups.google.com/group/uk.tech.digital-tv/msg/82ff55b36ba97dbf :
> In article <46ff32e0$0$32538$4c368...@roadrunner.com>,
> Green Xenon [Radium] <gluceg...@excite.com> wrote:
> >Within physical-possibility, what is the largest amount of
> >bits-per-symbol [assuming a baud-rate of only 1-bit-per-symbol]
> You just made a meaningless statement. Baud rate is measured in
> symbols per second, not bits per symbol. I assume that you meant to
> say "assuming a baud-rate of one symbol per second."
Yes. I meant "assuming a baud-rate of one symbol per second."
Sorry.
F-------king typos!!!!!!!!!!!!!!!!!!!!!!!!!!
If 400-nanometer-wavelength coherent light was used in place of electric
signals, would QM in this system be able to pack in more
bits-per-symbol. AFAIK, optical signals can have a greater dynamic range
than electric signals. That is one reason that optic fibers are
replacing coaxial cables. Less noise.
Dave Platt
Green Xenon [Radium] <gluc...@excite.com> wrote:
>If 400-nanometer-wavelength coherent light was used in place of electric
>signals, would QM in this system be able to pack in more
>bits-per-symbol. AFAIK, optical signals can have a greater dynamic range
>than electric signals. That is one reason that optic fibers are
>replacing coaxial cables. Less noise.
*sigh*
I give up.
Richard Crowley
> > "Green Xenon [Radium]" wrote ...
> > > Anyways, my next question. Is it possible to split the symbol of a
> > > 1
> > > baud, 8-bit-per-symbol signal
> > > into 8 bits? I.e. in this case, a single
> > > symbol would be split into 8 different
> > > parts each carrying one of the
> > > bits. Is this possible? If so, would
> > > this be of any assistance to me?
>
> > Sure it is possible. It won't be of any assistance to you (or to
> > anyone else since you can't put 8 pounds in a 1-pound sack.
> > Bandwidth is bandwidth, no matter how you slice it. Do you
> > really think that nobody has thought of various methods of
> > transmitting video over low-bandwidth paths? If so, you need
> > to study not only science and engineering but the HISTORY
> > of science and engineering.
>
> There are 8-bits-per-symbol, only 1 baud. The symbol is split into 8
> parts. Each part is 1-bit.
>
> How is this “putting 8 pounds in a 1-pound sack?”
>
> It’s more like “putting 1 pound in a 1-pound sack”
Which weighs more: one 8-pound sack, or eight 1-pound sacks?
Yes, it is a trick question, but you are the master of trick questions.
Bob Myers
"Richard Crowley" <rcro...@xp7rt.net> wrote in message
news:13g11vn...@corp.supernews.com...
> Which weighs more: one 8-pound sack, or eight 1-pound sacks?
> Yes, it is a trick question, but you are the master of trick questions.
Or we might ask our boy Radium this one:
Which weighs more, a pound of feathers or a pound of
gold? ;-)
Bob M.
John Williamson
1 troy ounce (Gold) = 1.09714 imperial ounces (Feathers)
12 Troy ounces = 1 Troy pound (Gold)
16 ounces = 1 pound (Feathers)
1 (troy) pound Gold = 0.822857 pounds (Imperial) feathers
Sorry to be picky...;-)
--
Tciao for Now!
John.
Don Bowey
Williamson" <johnwil...@btinternet.com> wrote:
> Bob Myers wrote:
>> "Richard Crowley" <rcro...@xp7rt.net> wrote in message
>> news:13g11vn...@corp.supernews.com...
>>> Which weighs more: one 8-pound sack, or eight 1-pound sacks?
>>> Yes, it is a trick question, but you are the master of trick questions.
>>
>> Or we might ask our boy Radium this one:
>>
>> Which weighs more, a pound of feathers or a pound of
>> gold? ;-)
>>
>>
> Errm...
Errm? Clearing your throat?
> 1 troy ounce (Gold) = 1.09714 imperial ounces (Feathers)
> 12 Troy ounces = 1 Troy pound (Gold)
> 16 ounces = 1 pound (Feathers)
>
> 1 (troy) pound Gold = 0.822857 pounds (Imperial) feathers
>
> Sorry to be picky...;-)
To be picky......... I'm sure it was assumed that both the feathers and gold
would be measured with the same scale.
Bob Myers
"John Williamson" <johnwil...@btinternet.com> wrote in message
news:fdrnc7$mi8$1...@stable.tornevall.net...
Oh, fine - just GIVE the answer away!
Why, pray tell, did you THINK I was suggesting this
question be asked of our dear friend Radium? Didn't
occur to you that there might actually be a reason I
chose those two particular materials?
Bob M.
Bob Myers
"Don Bowey" <dbo...@comcast.net> wrote in message
news:C326B53C.791C0%dbo...@comcast.net...
> To be picky......... I'm sure it was assumed that both the feathers and
> gold
> would be measured with the same scale.
Sorry, Don - bad assumption, which was the whole point of
the "trick question." But John W. just HAD to go and spoil
the fun before we could possibly see Radium jump in....sigh...
Bob M.
Don Bowey
<nospam...@address.invalid> wrote:
Well, Radium sets hooks far better that he takes one. I suspect he has no
interest in other's questions.
Michael A. Terrell
No, other than he's a gold bricking bird brain.
Halmyre
johnwil...@btinternet.com says...
There's a bit in one of Richard Feynmann's books where he's talking
about borrowing the US's silver reserves to make generator windings for
the Manhattan Project during WW2. The Treasury agreed to the request,
but took offence for being asked for several tons of silver, pointing
out that "we actually measure silver in ounces"...
--
Halmyre
Green Xenon [Radium]
So a higher-frequency modulation signal will result in more distant
sidebands than a lower-frequency modulation signal? E.g. a 10,000 Hz
tone will result in sidebands further from the base carrier frequency
than a 1,000 Hz signal?
Roderick Stewart
> >>So there is no way to decrease how far the sidebands will go?
>
> > With FM? Nope, not in the way you're hoping. Modulate a carrier Fc
> > with a frequency Fm, and the first sidebands will be at Fc+Fm and
> > Fc-Fm, just as would be true with AM. That's the narrowest you can
> > get.
>
> So a higher-frequency modulation signal will result in more distant
> sidebands than a lower-frequency modulation signal? E.g. a 10,000 Hz
> tone will result in sidebands further from the base carrier frequency
> than a 1,000 Hz signal?
By George! I think he's got it!
Rod.
Brian Gaff
Also there is often pre emphasis to look at as well.
Brian
--
Brian Gaff - bri...@blueyonder.co.uk
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Roderick Stewart" <escap...@removethisbit.beeb.net> wrote in message
news:VA.0000018...@removethisbit.beeb.net...
George
<gluc...@excite.com> wrote:
>Dave Platt wrote:
>
>> In article <46fc71d2$0$24285$4c36...@roadrunner.com>,
>> Green Xenon [Radium] <gluc...@excite.com> wrote:
>
>
>>>So there is no way to decrease how far the sidebands will go?
>
>
>> With FM? Nope, not in the way you're hoping. Modulate a carrier Fc
>> with a frequency Fm, and the first sidebands will be at Fc+Fm and
>> Fc-Fm, just as would be true with AM. That's the narrowest you can
>> get.
>
>
>
>So a higher-frequency modulation signal will result in more distant
>sidebands than a lower-frequency modulation signal? E.g. a 10,000 Hz
>tone will result in sidebands further from the base carrier frequency
>than a 1,000 Hz signal?
No, this is not true.
Both the 10,000 Hz and the 1,000 Hz tones will produce sidebands which
extend to infinity.
John Evans
<gluc...@excite.com> wrote:
>Dave Platt wrote:
>
>> In article <46fc71d2$0$24285$4c36...@roadrunner.com>,
>> Green Xenon [Radium] <gluc...@excite.com> wrote:
>
>
>>>So there is no way to decrease how far the sidebands will go?
>
>
>> With FM? Nope, not in the way you're hoping. Modulate a carrier Fc
>> with a frequency Fm, and the first sidebands will be at Fc+Fm and
>> Fc-Fm, just as would be true with AM. That's the narrowest you can
>> get.
Oh dear - what about the deviation?
The rule of thumb bandwidth required for FM (Carson's Rule) says the
bandwidth is given by
2x(peak deviation x highest modulating frquency).
So a system with a maximum modulating sinusoidal frequency of 15khz
using a deviation of 75khz needs 180khz bandwidth minimum.
Note a pulse would require a far greater bandwidth.
http://www.fmsystems-inc.com/eng_fm.htm
http://en.wikipedia.org/wiki/Frequency_modulation
gives
Jim Lesurf
<Geo...@stopspam.co.uk> wrote:
> On Sat, 27 Oct 2007 01:45:25 -0700, "Green Xenon [Radium]"
> <gluc...@excite.com> wrote:
> >
> >So a higher-frequency modulation signal will result in more distant
> >sidebands than a lower-frequency modulation signal? E.g. a 10,000 Hz
> >tone will result in sidebands further from the base carrier frequency
> >than a 1,000 Hz signal?
> No, this is not true.
..although it will be the case with the 10kHz modulation that none
of the sidebands will be closer than 10kHz from the carrier. Whereas
with 1kHz modulation they will start at 1kHz.
> Both the 10,000 Hz and the 1,000 Hz tones will produce sidebands which
> extend to infinity.
That is what textbooks say about an ideal case of one sinusoid modulated
with another.
But I suspect the posting you responded to assumed that we were talking
about sideband components with power levels significant enough to matter in
relevant real-world situations. Possibly even assuming the same sort of
peak deviation level without saying so. ;->
Fortunately:
A) The amplitude of the sideband components tends to fall rapidly towards
infinitesimally small as you move very far away from the carrier. Bessel
functions of the relevant type are like that.
B) Real world situations generally don't use ideal sinusoids, nor require
zero distortion. Nor use modulators and demodulators with infinite
bandwidths. Thus real modulation bandwiths have a tendency to be finite.
Thus reality only approximates to the simple textbook analysis you base
your statement upon. (Most texts avoid more complex modulations and the
effect of finite TX bandwidths like the plague as they can be a nightmare
to model analytically or explain, certainly at an undergrad level! The
tendency is to do simple mod, quote Carson's Rule, and quit while you
are ahead. :-) )
So - unless your interest is purely in trying to score a debating point by
nit-picking based simplifying what appears in undergrad texts - what was
your point? :-)
Slainte,
Jim
--
Electronics http://www.st-and.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Sjouke Burry
The troll may find yet another geeky side to ponder.
George
<jc...@st-and.demon.co.uk> wrote:
>
>So - unless your interest is purely in trying to score a debating point by
>nit-picking based simplifying what appears in undergrad texts - what was
>your point? :-)
>
>Slainte,
>
>Jim
If you examine this thread you might conclude that the question was
asked by someone seeking knowledge.
The first respondant took advantage of this to provide a sarcastic
put-down, which, incidentally, exposed his own ignorance.
Can you imagine the feelings of the questioner upon reading that
response to his honest question ?
That response was typical of many postings in this flaming Newgroup.
Your own posting is made entirely in the same spirit and you should be
ashamed.
By George.
Green Xenon [Radium]
Sorry but I am now confused. Dave said that a higher-frequency modulator
signal will result in wider sidebands than a lower-frequency modulator
signal. George says no to that. Jim then goes on about how it may or may
not be true. I am getting really confused.
Will someone please assist me in clearing this up?
Green Xenon [Radium]
> In article <ujr6i3dolk1qjon2i...@4ax.com>,
> John Evans wrote:
>
>
>>Oh dear - what about the deviation?
>
>
>>The rule of thumb bandwidth required for FM (Carson's Rule) says the
>>bandwidth is given by
>
>
>>2x(peak deviation x highest modulating frquency).
What is peak deviation measured in? Hz?
>
>>So a system with a maximum modulating sinusoidal frequency of 15khz
>>using a deviation of 75khz needs 180khz bandwidth minimum.
>
>
>>Note a pulse would require a far greater bandwidth.
Require a far greater bandwidth compared to what? A sine wave of the
same frequency and amplitude?
>
> Depends on the type of pulse. A wavelet might be about the same.
>
Are you talking about the pulses [bauds] of QAM signals?
"The carrier signal is characterized by the number of signal intervals,
or pulses, that are transmitted per second. Each pulse is called a baud."
Jim Lesurf
<Geo...@stopspam.co.uk> wrote:
> On Sat, 27 Oct 2007 17:56:13 +0100, Jim Lesurf <jc...@st-and.demon.co.uk>
> wrote:
> >
> >So - unless your interest is purely in trying to score a debating point
> >by nit-picking based simplifying what appears in undergrad texts - what
> >was your point? :-)
> >
> >Slainte,
> >
> >Jim
> If you examine this thread you might conclude that the question was
> asked by someone seeking knowledge.
If you examine the thread *in uk.tech.digital.tv* where I am reading and
replying, you will see that the start of the discussion was missing as only
some responses have been posted here. Afraid my conclusions are only
based on what has been posted where I read it.
> The first respondant took advantage of this to provide a sarcastic
> put-down, which, incidentally, exposed his own ignorance.
> Can you imagine the feelings of the questioner upon reading that
> response to his honest question ?
It might help if you addressed what I wrote about *your* posting. :-)
I was 'imagining' the feelings of the person whose posting I saw
you dismiss as untrue when you said that, but didn't give an
explanation which would have helped him to understand that, or
your comment.
> That response was typical of many postings in this flaming Newgroup.
Not clear which "flaming Newsgroup" you mean here.
> Your own posting is made entirely in the same spirit and you should be
> ashamed.
As things stand I am unable to comment. I am sorry if you are upset,
but perhaps you should have explained more clearly when you dismissed
what someone else as not being "true". That way the "spirit" of your
contribution would have been seen by me as being helpful rather than
- as here - critical. :-)
Jim Lesurf
[Radium] <gluc...@excite.com> wrote:
The problem here is that what 'George' said may well have confused your
understanding by introducting a point which is textbook correct, but was
misleading for you in this context without other information. That is why I
responded to him as I did, as I have see similar problems on many occasions
when undergrads have been confused in similar ways. Teaching requires
judgement about how you explain things, as well as patient effort by the
learner. :-)
To actually understand it is generally useful to start with a simplified
description and then only add in details later in a way that builds on the
initial, established, understanding. The snag is that this allows people to
nit-pick and point-score to show off how clever they are, but risks
confusing the person who wanted to learn, or make them think it is all to
complex for them to follow.
There is a fuller explanation of this in textbooks, and on the 'Scots
Guide' (address in my sig, below). But that is aimed at the undergrad level
student and assumes you're happy with the maths, so here is something
simpler.
Consider an example. Take a 1MHz sinusoid and modulate its frequency.
This 1MHz signal is often called the 'carrier' and we'd then say we have a
'carrier frequency' in this case of 1MHz.
Consider applying modulation with a 1kHz sinusoid as the modulation
waveform.
When considered as a sprectrum the result can be described as a series of
'sideband' components, spaced 1 kHz apart, centered on the carrier
frequency. So we'd get components at 1MHz + 1kHz, 1MHz + 2kHz, 1MHz +
3kHz, etc. Also at 1MHz - 1kHz, 1MHz - 2 kHz, etc...
In general, there will also still be a component at 1MHz.
The general rule is that the components are spaced at intervals equal to
the modulation frequency.
So if we'd used 10kHz modulation instead, then the sideband components
closest to the carrier would have been at 1MHz +/- 10kHz, the others at
+/-20, +/- 30, etc... Thus the interval between them has changed.
From the maths in the textbooks, these components nominally extend over an
infinite frequency range. But in reality they don't, and they amplitudes
tend to fall away to being insignificant when you look at frequencies a
long long way from the carrier.
The distribution of the amplitudes or powers of the components depends on
how large the modulation is, as well as the modulation frequency. So, all
else being equal, if you apply, say, 10kHz modulation, the components with
significant power levels will tend to spread out over a wider range of
frequencies than if we'd used 1kHz modulation.
The precise meaning of "significant power levels" will depend on the use
the FM system is being put to, and the conditions in which it is used.
However a general rule-of-thumb people use is 'Carson's Rule'. (If
interested in that, look for it on the Scots Guide.)
Thus the point you made in your first posting in this thread *as it has
appeared in the uk.tech.digital-tv group* is close to being correct, but
there are problems with your wording which would need clarifying.
All else being kept the same, Increasing the modulation frequency tends to
spread out the sideband power distribution and thus requires a wider
bandwidth. In practice a wider bandwidth tends to be required.
But purely in terms of undergrad textbooks, any sinusoidal modulation of a
sinusoid tends to give 'components' over an *infinite* range, so on that
basis what 'George' said is formally correct, and your wording wrong. Since
the components theoretically extend over an 'infinite' range, you can't say
that increasing the modulation frequency will "result in sidebands further
from the carrier" without qualifying that in some way like allowing for the
power levels, or some equivalent. What happens that the distribution of
power tends to spread out over a wider range of frequencies. (And hence the
information also tends to do so.)
The points he omitted are that some of [1] these 'components' well away
from the carrier may be of a size close enough to zero to be of no real
relevance, and that in real world systems no modulator or demodulator can
produce 'infinite' bandwidths. Thus he was showing he'd read the textbooks
which you hadn't, but confused you in the process. He was introducing the
formal need in the maths for an infinite set of components, where many/most
[1 again] of them will be infinitestimally small in power.
It would have been better if he'd then explained this, rather than simply
pronouncing that your comment wasn't "true". That way, his posting would
have been more helpful, rather than confusing for you. But it is always
easier - and quicker - to say someone else is wrong than it is to try to
give a useful explanation yourself. Explanations like this take time,
and may simply prompt someone else to nit-pick. :-)
If you want an example of how the modulation frequency affects the
spectrum, have a look at
http://www.st-and.demon.co.uk/temp/fmspectra.html
note, though, that this page was produced for another purpose so
uses more complicated modulations than a simple sinusoid. In
this case to show the effect of stereo (difference) modulation on
traditional stereo FM broadcasts. In this example the L-R or Right
only signals end up being modulation with higher modulation
frequencies, so tend to spread out the power-frequency spectrum
of the result. The first graphic shows this most clearly.
I'm afraid I can't comment on what might have been said in this discussion
prior to it starting being cross-posted to uk.tech.digital-tv as I haven't
seen that. If you or anyone else is simply engaged in a wind-up or trolling
I haven't seen that. So if what I write does not fit that context I am not
in a position at present to take that into account. Similarly, if 'George'
has lost patience as a result of fol-de-rols before this thread popped
up here in uk.tech.digital-tv I have no awareness of that, so can't
respond on that.
Slainte,
Jim
[1] Indeed infinitely many of them will be of infinitestimally small
amplitude. 8-] You could even have wonderful nit-picking debates about
if this was 'most' of them, or not, as you can get into playing word-games
in English about the relationships between different 'infinity' values and
subtracting finite values from them or taking ratios. c.f. discussions in
H2G2 about how much it rains. Beyond that I'll leave the question for
mathematicians and other theologians. :-)
Green Xenon [Radium]
In the original post of the "Using an FM-Carrier for the Y [Luminance]
Signal -- how to relieve the bandwidth issue?" I was describing
converting the luminance signal to QAM and then broadcasting the QAM
video on a ULF [300 Hz] FM carrier in which the QAM uses
1-symbol-per-second and a sufficient amounts of bits-per-symbol to
represent the video.
Unfortunately for me, it is not possible to do this.
spamtr...@gmail.com
wrote:
> Paul Martin wrote:
> > Depends on the type of pulse. A wavelet might be about the same.
>
> Are you talking about the pulses [bauds] of QAM signals?
>
> Quotes fromhttp://www.howstuffworks.com/framed.htm?parent=modem.htm&url=http://w...
> :
>
> "The carrier signal is characterized by the number of signal intervals,
> or pulses, that are transmitted per second. Each pulse is called a baud."
Wrong. A bawd is an elderly slut. You mean a bit.
Matti Lamprhey
Wrong. The baud is a measure of signalling changes per second. Each
signalling change can involve multiple bits of data. Therefore
bits-per-sec is not equivalent to baud rate (although in practice it
used to be in primitive modems).
Matti
spamtr...@gmail.com
reversed.com> wrote:
> <spamtrap1...@gmail.com> wrote...
So, a baud is really an inverse second.
Matti Lamprhey
No - you're thinking of the unit which later went into Van Rental.
Matti
Andy Champ
On a 1-bit-per-transition line, the baud rate is the bit rate. On a
parallel or multi-level transmission medium it is *not*.
There a nice article at
http://en.wikipedia.org/wiki/Baud
Which is much better than the one I just wrote and threw away!
Andy
Green Xenon [Radium]
I'd like my QAM video signal to be at least 1-billion-bits-per-symbol
but no more than 1-symbol-per-second. I then want to transmit this video
signal on an ULF FM radio signal whose carrier wave is only 300 Hz.
Lord please make this physically-possible. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please. God
please. God please. God please. God please. God please. God please.
<praying until death from exhaustion>
Roderick Stewart
wrote:
> I'd like my QAM video signal to be at least 1-billion-bits-per-symbol
> but no more than 1-symbol-per-second. I then want to transmit this video
> signal on an ULF FM radio signal whose carrier wave is only 300 Hz.
>
> Lord please make this physically-possible. God please. God please. God
> please. God please. God please. God please. God please. God please.
>
> <praying until death from exhaustion>
I don't think he's listening. What's possible is possible and what isn't
isn't, and that's that.
Rod.
Green Xenon [Radium]
Dayum! Just when I was thinking I could change everything by requesting
the Lord to do so!
My euphoria just become dysphoria!
CRRRRRRRRRRRRRRRRRRRRAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAASSSSSSSSSSSSSSSSSSSSSSSHHHHHHHHHHHHHHHHHHH!
spamtr...@gmail.com
A baud used to be a bit time per second (per the historic referenced
article in wiki) and now no longer is. Fine. But baud is still a rate:
symbols per second; whereas a pulse (from "howstuffworks") is not a
rate and thus cannot be a baud.
Bob Myers
"Green Xenon [Radium]" <gluc...@excite.com> wrote in message
news:4727a189$0$19640$4c36...@roadrunner.com...
> I'd like my QAM video signal to be at least 1-billion-bits-per-symbol but
> no more than 1-symbol-per-second. I then want to transmit this video
> signal on an ULF FM radio signal whose carrier wave is only 300 Hz.
I realize you're again just either trolling or so astoundingly ignorant of
the field that it's amazing you're walking around without a keeper,
but...why?
What possible advantage would such a system have, if it were possible
in the first place (which it isn't, not by a rather large number of orders
of magnitude)?
And what in the hell does "QAM video signal" on an "FM radio signal"
mean in the first place?
Bob M.
Bob Myers
<spamtr...@gmail.com> wrote in message
news:1193864474.2...@i38g2000prf.googlegroups.com...
> A baud used to be a bit time per second (per the historic referenced
> article in wiki)
Trust ye not in Wiki. "Baud rate" NEVER meant the same as
"bit rate" - the two just happened to be the same number in
early 1 bit/symbol systems.
Bob M,
Green Xenon [Radium]
> "Green Xenon [Radium]" <gluc...@excite.com> wrote in message
> news:4727a189$0$19640$4c36...@roadrunner.com...
>
>
>>I'd like my QAM video signal to be at least 1-billion-bits-per-symbol but
>>no more than 1-symbol-per-second. I then want to transmit this video
>>signal on an ULF FM radio signal whose carrier wave is only 300 Hz.
>
>
> I realize you're again just either trolling or so astoundingly ignorant of
> the field that it's amazing you're walking around without a keeper,
> but...why?
>
> What possible advantage would such a system have, if it were possible
> in the first place (which it isn't, not by a rather large number of orders
> of magnitude)?
Okay I got a bit carried away here. Sorry. 1-billion-bits-per-symbol is
equivalent allows for 2^1,000,000,000 voltages. This is not possible.
Just an imagination. Please forgive me and forget about it.
Anyways, the QAM should be given the highest practical bit-resolution.
1-symbol-per-second should be the baud.
The following is interesting but only theoretically-possible. Not gonna
happen with today's technology:
The minimum voltage should be set to 1.6e-19 volt. This is the voltage
of one electron. The maximum voltage should be set to the highest you
can get *without* doing any of the following to any extent:
1. Exceeding the dielectric strength of any electronic component
2. Generating temperatures above 70 Fahrenheit in any electronic component
3. Ionizing any electronic component
The bit-resolution should be high enough that each "level" is a
difference of 1.6e-19 volt from the level above/below. A resolution of
8-bit allows for only 256 different levels -- obviously *way* too low.
>
> And what in the hell does "QAM video signal" on an "FM radio signal"
> mean in the first place?
>
Again, the following is interesting but only theoretically-possible. Not
gonna happen with today's technology:
The original Y signal is converted to QAM. This QAM signal is then
broadcasted on an FM radio carrier wave whose base frequency is 300 Hz.
300 Hz is the lowest ULF frequency and the lowest frequency used by
telephones.
http://en.wikipedia.org/wiki/Ultra_low_frequency
Prior to converting the Y signal to QAM, the temporal and spatial
frequencies [excluding DC -- 0 hertz] are downshifted in real time [sort
of like the video-equivalent of the voice-changers used on the phone
which can decrease the pitch of your voice in real time without
decreasing the speed of your speech]. This frequency downshifting does
not involve decreasing the "speeds" of the temporal or spatial
components of the Y-signal. All temporal and spatial frequencies other
than zero-hertz are shifted closer to zero. This decreases the bandwidth
of the Y-signal. No low-pass filtering. No changing the speed of the
temporal signal. No changing the size of the spatial signal.
Even though the spatial signal does not have "speed" as its component
because it is -- by nature -- static, it does have an equivalent which I
have a hard time figuring out. Perhaps it’s the size? Decreasing the
"speed" might involve increasing the size of the image? I am guessing
this is the case.
There are many audio softwares that allow downshifting the frequencies
of music until they are closer to zero. They can do this without slowing
the playback speed or increasing the length of the song. If a frequency
is zero Hz, its stays at zero. However, if a frequency is not zero, it
is shifted closer to zero.
Apparently -- from what I see on the graph my audio software [Adobe
Audition 1.5] -- downshifting decreases the amount of cycles per
distance and then increases the lengths of the waves. So basically the
signal does not take up more space than it did prior to the
pitch-shifting. The amount of waves per area decreases but the remaining
waves are increased in length, so the distance from where the waves
started to where they finish do not decrease -- their lengths increase
but their amounts decrease. So overall, the distance from start to
finish remains the same. Hence the file’s length does not change.
The real-time-video-equivalent of the above is done to decrease the
overall frequency [and bandwidth] of the Y-signal prior to converting it
to QAM. A sufficient amount of this frequency-downshifting is done to
the original Y-signal such that the resulting QAM signal does not cause
the FM signal to develop sidebands beyond 301 Hz or 299 Hz -- sideband
is only 1 Hz + or - from baseband.
Equally important, prior to conversion to QAM, the amplitude levels of
the Y-signal are brought closer to the neutral without decreasing the
amount of levels -- darker than neutral result is represented by a
negative electric current while brighter than neutral is represented as
a positive electric current. When the Y-signal is at medium light
intensity, the current is neutral [i.e. right on the x-axis of a graph
when measured]. Anyways, all of the brightness levels are shifted
towards the x-axis so that the resulting QAM signal will not cause the
FM radio signal's frequency to deviate beyond 301 Hz or 299 Hz -- peak
deviation is only 1 Hz + or - from baseband.
In a luminance signal, the medium light intensity is represented by
voltages that are neither positive nor negative. If the light intensity
increases above the medium brightness, a positive voltage results. If
the light intensity falls below medium brightness, a negative voltage
results. This is because the Y-signal is represented by AC current.
The chroma along with instructions regarding how to reverse-process the
Y-signal [so the original Y-signal is retrieved] -- as well as properly
linking the chroma with the luma -- is delivered from the transmitting
end to the receiving end via optic fibers. That way the equipment
receiving the FM video signal can best decode the video back to how it
originally looked -- not exactly how it looked but close.
One potential disadvantage of this tech is the white flashes on the
receiver's screen when there are electrical storms in the atmosphere
[such as lightning], or manmade electric disturbances such as florescent
lamps and automobile ignitions. Such visual interferences are worse
during cloudy/rainy weather -- even if there is no lightning. The
reception maybe FM, but the receiver is built to be extremely sensitive
to the extremely low power signals emitted from the transmitting end.
This FM receiver can coherently receive frequency-modulated 300 Hz
electromagnetic signals as weak as 1.3e-24 watts per
square meter. This weak signal is equivalent to 1 photon per second per
square meter.
Turn on a distant xenon-lamp [on the otherside of the world] and boom!
The monitor displaying the video signals will start to show some
interesting white disruptions -- dancing zig-zag lines, sawtooth waves,
etc. That’s how sensitive this receiver is.
Bob Myers
> Anyways, the QAM should be given the highest practical bit-resolution.
> 1-symbol-per-second should be the baud.
Fine, but the question remains - what the hell is so important
about "1 symbol per second"? Why do you CARE?
> The minimum voltage should be set to 1.6e-19 volt. This is the voltage of
> one electron.
Wrong. Electrons have charge, expressed in coulombs, not
voltage. Go figure out the difference, and come back.
>
> The bit-resolution should be high enough that each "level" is a difference
> of 1.6e-19 volt from the level above/below. A resolution of 8-bit allows
> for only 256 different levels -- obviously *way* too low.
Way too low for WHAT?
> The original Y signal is converted to QAM. This QAM signal is then
> broadcasted on an FM radio carrier wave whose base frequency is 300 Hz.
> 300 Hz is the lowest ULF frequency and the lowest frequency used by
> telephones.
Restating nonsense doesn't make it less nonsensical. What does
"QAM...on an FM radio carrier wave" MEAN on your planet?
The rest is just gibberish as well.
Bob M.
Green Xenon [Radium]
> "Green Xenon [Radium]" <gluc...@excite.com> wrote in message
> news:47295e0d$0$11519$4c36...@roadrunner.com...
>
>>Anyways, the QAM should be given the highest practical bit-resolution.
>>1-symbol-per-second should be the baud.
> Fine, but the question remains - what the hell is so important
> about "1 symbol per second"? Why do you CARE?
I want to send the most information using the least bandwidth.
>>The minimum voltage should be set to 1.6e-19 volt. This is the voltage of
>>one electron.
> Wrong. Electrons have charge, expressed in coulombs, not
> voltage. Go figure out the difference, and come back.
A charge can generate a voltage. An area with one free electron vs. a
area with no free electrons has a difference of 1.6e-19 volt because a
single electron has a negative charge of 1.6e-19 coulomb.
>>The bit-resolution should be high enough that each "level" is a difference
>>of 1.6e-19 volt from the level above/below. A resolution of 8-bit allows
>>for only 256 different levels -- obviously *way* too low.
> Way too low for WHAT?
Deciphering all those voltage levels with differences of 1.6e-19 volt
and with 1.6e-19 volt being the lowest voltage and the maximum voltage
being just low enough *not* to do any of the following to any extent:
1. Exceed the dielectric strength of any electronic component
2. Generate temperatures above 70 Fahrenheit in any electronic component
3. Ionize any electronic component
8-bits of resolution simply isn't *nearly* enough for this task.
>>The original Y signal is converted to QAM. This QAM signal is then
>>broadcasted on an FM radio carrier wave whose base frequency is 300 Hz.
>>300 Hz is the lowest ULF frequency and the lowest frequency used by
>>telephones.
> Restating nonsense doesn't make it less nonsensical. What does
> "QAM...on an FM radio carrier wave" MEAN on your planet?
A QAM signal in broadcasted on an FM radio wave. What don't you
understand about this?
> The rest is just gibberish as well.
How so?
Andy Champ
>
> Trust ye not in Wiki. "Baud rate" NEVER meant the same as
> "bit rate" - the two just happened to be the same number in
> early 1 bit/symbol systems.
>
> Bob M,
>
>
That article was mostly right when I looked at it, or I wouldn't have
mentioned it. Some odd stuff about gigabit ethernet now though...
Andy
Green Xenon [Radium]
> Deciphering all those voltage levels with differences of 1.6e-19 volt
> and with 1.6e-19 volt being the lowest voltage and the maximum voltage
> being just low enough *not* to do any of the following to any extent:
>
> 1. Exceed the dielectric strength of any electronic component
>
> 2. Generate temperatures above 70 Fahrenheit in any electronic component
>
> 3. Ionize any electronic component
>
> 8-bits of resolution simply isn't *nearly* enough for this task.
The reason is because there are obviously a *lot* more than 256 voltage
levels in the above.
> A QAM signal in broadcasted on an FM radio wave.
Sorry. That should read "A QAM signal *is* broadcasted on an FM radio
wave."
F--king typos!
John Fields
<gluc...@excite.com> wrote:
>Bob Myers wrote:
>> The rest is just gibberish as well.
>
>How so?
---
Clearly, anything you post is gibberish and an attempt to get
attention by having others try to correct your intentional nonsense.
--
JF