Using an FM-Carrier for the Y [Luminance] Signal -- how to relieve the bandwidth issue?
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Green Xenon [Radium]
One major reason the luminance signals of television are broadcasted on
an AM-carrier instead of FM is because FM requires large amounts of
bandwidth. Is there a way to use FM video without hogging so much bandwidth?
Quotes from
http://groups.google.com/group/sci.electronics.basics/msg/0c013cf5371da8dc?hl=en&
:
>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.
>http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation
>http://en.wikipedia.org/wiki/Constellation_diagram
Does this mean that Quadrature Modulation and Constellation Modulation
can -- at least in theory -- be applied to FM video so that excessive
bandwidth is not needed? If so, then what would be the minimum
radio-frequency required to transmit the video signal?
Thanks,
Radium
![Brian Gregory [UK]'s profile photo](https://lh3.googleusercontent.com/a/default-user=s40-c)
Brian Gregory [UK]
news:46f6d850$0$11068$4c36...@roadrunner.com...
No.
These are like special modified forms of AM.
You can only use these to reduce bandwidth of an FM signal in the same way
that you can use AM to reduce the bandwidth of an FM signal. It just won't
be FM any more.
--
Brian Gregory. (In the UK)
n...@bgdsv.co.uk
To email me remove the letter vee.
Graham.
"Green Xenon [Radium]" <gluc...@excite.com> wrote in message
news:46f6d850$0$11068$4c36...@roadrunner.com...
Brian, with a cross-post list like that, this guy has got to be a troll.
Brendan Gillatt
Hash: SHA1
Okay now you're actualy irritating me quite a LOT.
Please, do yourself a favour: buy an Amazon book voucher and shut up.
- --
Brendan Gillatt
brendan {at} brendangillatt {dot} co {dot} uk
http://www.brendangillatt.co.uk
PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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Green Xenon [Radium]
> No.
>
> These are like special modified forms of AM.
>
> You can only use these to reduce
> bandwidth of an FM signal
> in the same way that you
> can use AM to reduce the
> bandwidth of an FM signal.
> It just won't be FM any more.
Would using Quadrature Frequency Modulation be of any help?
Quadrature Amplitude Modulation uses a combo of AM and Phase-Shift-Keying.
So QFM would use a combination of FM and PSK. Would this decrease the
bandwidth required for broadcasting FM luminance video signals?
Green Xenon [Radium]
> Brian, with a cross-post list like that,
> this guy has got to be a troll.
No. I am just posting questions that I find interesting. I cross-posted
only to relevant NGs.
Green Xenon [Radium]
<brendanREMOVET...@brendanREMOVETHISgillatt.co.uk> wrote in
http://groups.google.com/group/uk.tech.digital-tv/msg/4c903b0a453a39fa :
> Okay now you're actualy irritating me quite a LOT.
How so? I am just asking extremely interesting questions about video
technology.
> Please, do yourself a favour: buy an Amazon book voucher and shut up.
I’ve tried painfully hard to answer my questions doing my own research
-- including reading information from books. I still haven’t found
answers to my questions. That is why I am turning to NGs for assistance.
Is Quadrature Frequency Modulation used? What for?
AFAIK, Quadrature Amplitude Modulation uses a combo of AM and
Phase-Shift-Keying.
So QFM would use a combination of FM and PSK. Would this decrease the
bandwidth required for broadcasting FM luminance video signals?
I did a Google Search for “Quadrature Frequency Modulation” on
http://www.google.com/search?hl=en&lr=&q=%22Quadrature+Frequency+Modulation+%22&btnG=Search
None of those pages made any sense to me.
One major reason the luminance signals of television are broadcasted on
an AM-carrier instead of an FM-carrier is because FM requires large
amounts of bandwidth. Is there a way to use FM video without hogging so
much bandwidth using QFM?
Quotes from
http://groups.google.com/group/sci.electronics.basics/msg/0c013cf5371da8dc?hl=en&
:
> 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.
> http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation
>
> http://en.wikipedia.org/wiki/Constellation_diagram
Does this mean that the FM-equivalents-of-QAM and Constellation
Modulation can -- at least in theory -- be applied to FM video so that
excessive bandwidth is not needed? If so, then what would be the minimum
radio-frequency required to transmit the video signal? Is a 150 kHz
radio-frequency sufficient to be an FM carrier for this video signal?
Constellation modulation is a type of AM. What’s the FM-equivalent of
constellation modulation?
Has multiple-level QFM ever been used for video before?
Brian Gregory [UK]
> Would using Quadrature Frequency Modulation be of any help?
>
> Quadrature Amplitude Modulation uses a combo of AM and Phase-Shift-Keying.
>
> So QFM would use a combination of FM and PSK. Would this decrease the
> bandwidth required for broadcasting FM luminance video signals?
Think about it.
Obviously there is no way FM and PSK can be going on at the same time in any
way that can convey separate information. Worse still if you separately FM
modulate two signals that start in quadrature with each other they won't
stay in quadrature.
Adrian C
> Brian, with a cross-post list like that, this guy has got to be a troll.
>
He is. Has moved on from pestering "alt.engineering.electrical"
:-(
--
Adrian C
Steven
> "Green Xenon [Radium]" <gluceg...@excite.com> wrote in messagenews:46f6f08e$0$16535$4c36...@roadrunner.com...
Okay, I'll bite too. Why are you wanting to PSK? If you put them in
quadrature won't the phase differences try to cancel at points and
cause a mess?
Note: not my area of expertise but Brian raises some good points.
Wouldn't placing it in odd numbers on the carrier axis present fewer
problems...in other words IIRC the "constellation" mentioned earlier?
3 or 5 perhaps.
Would I be correct in thinking the Grand Alliance must have thought
around these lines originally before settling on an all-digital
system? It doesn't sound too feasable because it would take a lot to
duplicate all this signal and the transmissions would be awfully weak
IMO.
Anybody who has studied IBOC FM knows that the analog carrier noise
increases with IBOC added and each HD subchannel adds to this. The
laws of physics demand more power for those signals and it comes from
the analog signal in the end if you do not increase the total power,
which you cannot do given the nature of the allocations and power
restrictions given by the government. Only an ALL-DIGITAL system in
the end is not a compromise and burden to the existing channels.
Feel free to correct me where I'm goofy and thanks to the OP for
bringing up what I DON'T find boring or spam. I hope we're helping him
and you're doing the same.
Brendan Gillatt
Hash: SHA1
Green Xenon [Radium] wrote:
> On Sep 23, 3:02 pm, Brendan Gillatt
> <brendanREMOVET...@brendanREMOVETHISgillatt.co.uk> wrote in
> http://groups.google.com/group/uk.tech.digital-tv/msg/4c903b0a453a39fa :
>
>> Okay now you're actualy irritating me quite a LOT.
>
> How so? I am just asking extremely interesting questions about video
> technology.
>
>> Please, do yourself a favour: buy an Amazon book voucher and shut up.
>
> I’ve tried painfully hard to answer my questions doing my own research
> -- including reading information from books. I still haven’t found
> answers to my questions. That is why I am turning to NGs for assistance.
AGGGHHHHH.... plonk
- --
Brendan Gillatt
brendan {at} brendangillatt {dot} co {dot} uk
http://www.brendangillatt.co.uk
PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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Green Xenon [Radium]
http://groups.google.com/group/uk.tech.digital-tv/msg/e3f02036509d6ca6 :
> "Green Xenon [Radium]" <gluceg...@excite.com> wrote in
messagenews:46f6f08e$0$16535$4c36...@roadrunner.com...
>
> > So QFM would use a combination of FM and PSK.
> > Would this decrease the
> > bandwidth required for broadcasting
> > FM luminance video signals?
> Think about it.
> Obviously there is no way FM and PSK can
> be going on at the same time in any
> way that can convey separate information.
How about FM and FSK [Frequency-Shift-Keying]?
Would this work if FSK is used in place of PSK?
> Worse still if you separately FM
> modulate two signals that start in
> quadrature with each other they won't
> stay in quadrature.
Okay. Then what is the *practical* FM-equivalent of QAM?
Brian Gregory [UK]
> On Sep 23, 3:02 pm, Brendan Gillatt
> <brendanREMOVET...@brendanREMOVETHISgillatt.co.uk> wrote in
> http://groups.google.com/group/uk.tech.digital-tv/msg/4c903b0a453a39fa :
>
> including reading information from books. I still haven’t found answers to
> my questions. That is why I am turning to NGs for assistance.
>
> Is Quadrature Frequency Modulation used? What for?
>
> AFAIK, Quadrature Amplitude Modulation uses a combo of AM and
> Phase-Shift-Keying.
>
> So QFM would use a combination of FM and PSK. Would this decrease the
> bandwidth required for broadcasting FM luminance video signals?
>
> I did a Google Search for “Quadrature Frequency Modulation” on
> http://www.google.com/search?hl=en&lr=&q=%22Quadrature+Frequency+Modulation+%22&btnG=Search
>
> None of those pages made any sense to me.
I had a quick look at a few of them.
Some guy seems to be trying to patent something he calls Quadrature
Frequency Modulation. I see this as similar to the many perpetual motion
machines that get patented.
If it works at all I can't see it offering anything different from QPSK (aka
QAM4) in performance or bandwidth requirements.
Green Xenon [Radium]
http://groups.google.com/group/uk.tech.digital-tv/msg/ce3d79d5140e6b39 :
> Anybody who has studied IBOC FM knows that the analog carrier noise
> increases with IBOC added and each HD subchannel adds to this. The
> laws of physics demand more power for those signals and it comes from
> the analog signal in the end if you do not increase the total power,
> which you cannot do given the nature of the allocations and power
> restrictions given by the government. Only an ALL-DIGITAL system in
> the end is not a compromise and burden to the existing channels.
What is IBOC?
Richard Crowley
> What is IBOC?
If you would learn to look up things like this on Google and/
or Wikipedia, it would dramatically increase your apparent
intelligence. You might find yourself actually learning
something instead of making a nuisance of yourself on
Usenet asking silly questions.
Brian Gregory [UK]
Actually, come to think of it, thinking of QAM as a combination of AM and
PSK isn't at all helpful.
I think QAM should be thought of as two carriers in quadrature with each
other each being AM modulated, that is multiplied by numbers (which can be
both positive and negative). The overall phase of the generated QAM signal
(sum of the two carriers) does shift about as does the overall amplitude but
treating them separately will not help you demodulate the QAM.
I don't think I have much more to say on this subject.
Michael A. Terrell
radium is a troll. he tries this crap on a lot ot different
newsgroups, and asks stupid questions to entertain himself. If you
don't believe me. look at his posting history on Google Groups, then
kill file him.
--
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
Roderick Stewart
wrote:
> I'm not an really an expert either.
>
> Actually, come to think of it, thinking of QAM as a combination of AM and
> PSK isn't at all helpful.
>
> I think QAM should be thought of as two carriers in quadrature with each
> other each being AM modulated, that is multiplied by numbers (which can be
> both positive and negative).
There's something awfully familiar about that description. I'm sure I've read
about it in a book somewhere.
Oh yes, that Mullard book about PAL television I read at school 40 years ago.
Rod.
Steven
<brendanREMOVET...@brendanREMOVETHISgillatt.co.uk> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Green Xenon [Radium] wrote:
> > On Sep 23, 3:02 pm, Brendan Gillatt
> > <brendanREMOVET...@brendanREMOVETHISgillatt.co.uk> wrote in
> >http://groups.google.com/group/uk.tech.digital-tv/msg/4c903b0a453a39fa:
>
> >> Okay now you're actualy irritating me quite a LOT.
>
> > How so? I am just asking extremely interesting questions about video
> > technology.
>
> >> Please, do yourself a favour: buy an Amazon book voucher and shut up.
>
> > I've tried painfully hard to answer my questions doing my own research
> > -- including reading information from books. I still haven't found
> > answers to my questions. That is why I am turning to NGs for assistance.
>
> AGGGHHHHH.... plonk
>
> - --
> Brendan Gillatt
> PGP Key:http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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> =YeLk
> -----END PGP SIGNATURE-----
goodbye brendan...have a nice enema
Steven
Mr. Crowley!
Steven
wrote:
> "Brian Gregory [UK]" wrote:
>
> > "Green Xenon [Radium]" <gluceg...@excite.com> wrote in message
> >news:46f6d850$0$11068$4c36...@roadrunner.com...
> > > Hi:
>
> > > One major reason the luminance signals of television are broadcasted on an
> > > AM-carrier instead of FM is because FM requires large amounts of
> > > bandwidth. Is there a way to use FM video without hogging so much
> > > bandwidth?
>
> > > Quotes from
We're all trolls, damn you, least the exceptional you.
Green Xenon [Radium]
http://groups.google.com/group/uk.tech.digital-tv/msg/6a386fec832f1ef5 :
> "Green Xenon [Radium]" <gluceg...@excite.com> wrote in
messagenews:46f6d850$0$11068$4c36...@roadrunner.com...
>
> > Hi:
> > One major reason the luminance signals of
> > television are broadcasted on an
> > AM-carrier instead of FM is
> > because FM requires large amounts of
> > bandwidth. Is there a way to use FM video
> > without hogging so much
> > bandwidth?
> > Quotes from
> >
http://groups.google.com/group/sci.electronics.basics/msg/0c013cf5371da8dc?hl=en&
:
> >
> >
> > >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.
> > >http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation
> > >http://en.wikipedia.org/wiki/Constellation_diagram
> > Does this mean that Quadrature Modulation
> > and Constellation Modulation
> > can -- at least in theory -- be applied
> > to FM video so that excessive
> > bandwidth is not needed? If so, then
> > what would be the minimum
> > radio-frequency required to transmit the video signal?
> No.
>
> These are like special modified forms of AM.
>
> You can only use these to reduce
> bandwidth of an FM signal in the same way
> that you can use AM to reduce
> the bandwidth of an FM signal.
> It just won't
> be FM any more.
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.
Quotes from http://en.wikipedia.org/wiki/Baud :
“Conveying more than one bit per symbol has advantages. It reduces the
time required to send a given quantity of data, and allows modern
modems, FDDI and 100/1000 Mbit/s Ethernet LANs, and others, to achieve
high data rates. An optimal symbol set design takes into account channel
bandwidth, desired information rate, noise characteristics of the
channel and the receiver, and receiver and decoder complexity. A typical
2400-bit/s modem transmits at 600 baud (600 symbol/s), where each
quadrature amplitude modulation symbol carries four bits of information.
1000 Mbit/s Ethernet LAN cables use many wire pairs and many bits per
symbol to encode their data payloads. 1000BASE-T uses four wire pairs
and two data bits per symbol to get a symbol rate of 125MBd.”
“So the technique is to try and "pack" as many bits as you can into 1 baud.”
So it’s always best to use the most amounts of bits-per-baud but no more
than 1 baud
bps = baud * number of bits per baud.
Remember, keep the baud no more than one-symbol-per-second but at the
same time, convey as many bits-per-symbol as mathematically and
physically possible.
Then, hopefully, it will be possible to transmit/receive video signals
on FM carriers with radio-frequencies below the medium-wave band --
without stealing bandwidth from existing stations using those
frequencies -- or frequencies near those stations.
http://en.wikipedia.org/wiki/Medium-wave
MW = from 530 kHz up to 1610 kHz
Dave Platt
Green Xenon [Radium] <gluc...@excite.com> wrote:
>Then, hopefully, it will be possible to transmit/receive video signals
>on FM carriers with radio-frequencies below the medium-wave band --
>without stealing bandwidth from existing stations using those
>frequencies -- or frequencies near those stations.
Hope all you want, guy.
Don't hold your breath while you're hoping for it, though.
To understand why, Google the "Shannon Limit".
--
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!
Steven
> In article <46f86fa7$0$9596$4c368...@roadrunner.com>,
> Green Xenon [Radium] <gluceg...@excite.com> wrote:
>
> >Then, hopefully, it will be possible to transmit/receive video signals
> >on FM carriers with radio-frequencies below the medium-wave band --
> >without stealing bandwidth from existing stations using those
> >frequencies -- or frequencies near those stations.
>
> Hope all you want, guy.
>
> Don't hold your breath while you're hoping for it, though.
>
> To understand why, Google the "Shannon Limit".
That Shannon sure is limited!
Lostgallifreyan
news:1190675562.7...@r29g2000hsg.googlegroups.com:
And THAT was the point at which you bring this elevating little debate to
yet another newsgroup, which had so far been fortunate enough not to have
to hear the shouting.
I won't see the reply if any, I removed the group's name to spare it, it
has enough useless posts already.
Arny Krueger
news:5lqd5gF...@mid.individual.net
Agreed that asking questions that are well-answered in the first page of a
simple google retrieval pretty well defines "nuisance".
Rick Merrill
"...signal power through an analog communication channel subject to
additive white Gaussian noise..."
In other words it is obsolete because FM video is going away on Feb 18,
2009.
Brian Gregory [UK]
news: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'm beginning to think you are a troll.
Richard Crowley
> Why make it use more bandwidth by introducing totally superfluous FM
> modulation??
>
> I'm beginning to think you are a troll.
Others have come to the same conclusion months ago.
Sjouke Burry
and crossposting all over the place, hoping to score from
people who think the questions are legit.