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Why not rake receivers for DTV?

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Anonymous
October 6, 2004 9:49:52 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

I work in the 3G mobile phone industry, and there the receivers
are designed to take advantage of reflected signals. They have
what is known as a rake receiver that searches for reflections
and then samples the signal with various amounts of delay
so that all reflections are recieved in sync. Because the
mobile is often constantly moving, the rake "fingers" are
added and removed at a high rate. In the end, the reflections
actually provide better signal quality.

Whis is this not done for HDTV? I admit I know nothing about
HDTV encoding and modulation, so perhaps the rates are just
too high.

Regards,
Jatian

More about : rake receivers dtv

October 7, 2004 2:16:16 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

You answered your own question: "I admit I know nothing about HDTV...."

"JatJatIan" <jatjatian@yahoo.co.uk> wrote in message
news:aacc5e60.0410061649.c56f654@posting.google.com...
> I work in the 3G mobile phone industry, and there the receivers
> are designed to take advantage of reflected signals. They have
> what is known as a rake receiver that searches for reflections
> and then samples the signal with various amounts of delay
> so that all reflections are recieved in sync. Because the
> mobile is often constantly moving, the rake "fingers" are
> added and removed at a high rate. In the end, the reflections
> actually provide better signal quality.
>
> Whis is this not done for HDTV? I admit I know nothing about
> HDTV encoding and modulation, so perhaps the rates are just
> too high.
>
> Regards,
> Jatian
October 7, 2004 2:16:17 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

>> Whis is this not done for HDTV? I admit I know nothing about
>> HDTV encoding and modulation, so perhaps the rates are just
>> too high.
>>
>> Regards,
>> Jatian
>
On Wed, 6 Oct 2004 22:16:16 -0400, "curmudgeon"
<curmudgeon@buzzoff.net> wrote:

>You answered your own question: "I admit I know nothing about HDTV...."
-----------------------------
No, he didn't answer his own question. He's inquiring about whether a
technique for signal acquisition used in one field of communications
is applicable in another. A legitimate question, and he's being humble
about it.

If you're so smart, why don't you try to provide a thoughtful answer
instead of spouting off nonsense? Afraid of straining your weeny
little brain?

Buzzoff curmudgeon.
Related resources
October 7, 2004 9:21:07 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

"JatJatIan" <jatjatian@yahoo.co.uk> wrote in message
news:aacc5e60.0410061649.c56f654@posting.google.com...
>I work in the 3G mobile phone industry, and there the receivers
> are designed to take advantage of reflected signals. They have
> what is known as a rake receiver that searches for reflections
> and then samples the signal with various amounts of delay
> so that all reflections are recieved in sync. Because the
> mobile is often constantly moving, the rake "fingers" are
> added and removed at a high rate. In the end, the reflections
> actually provide better signal quality.
>
> Whis is this not done for HDTV? I admit I know nothing about
> HDTV encoding and modulation, so perhaps the rates are just
> too high.
>
> Regards,
> Jatian

The January debut of a fifth generation LG receiver is supposed to do just
that. There is an article at

http://www.keepmedia.com/pubs/BroadcastEngineering/2004...

but it requires registration. Other links have been posted before.

Pat
Anonymous
October 7, 2004 4:57:22 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Greywolf wrote:
> "JatJatIan" <jatjatian@yahoo.co.uk> wrote in message
> news:aacc5e60.0410061649.c56f654@posting.google.com...
>
>>I work in the 3G mobile phone industry, and there the receivers
>>are designed to take advantage of reflected signals. They have
>>what is known as a rake receiver that searches for reflections
>>and then samples the signal with various amounts of delay
>>so that all reflections are recieved in sync. Because the
>>mobile is often constantly moving, the rake "fingers" are
>>added and removed at a high rate. In the end, the reflections
>>actually provide better signal quality.
>>
>>Whis is this not done for HDTV? I admit I know nothing about
>>HDTV encoding and modulation, so perhaps the rates are just
>>too high.
>>
>>Regards,
>>Jatian
>
>
> The January debut of a fifth generation LG receiver is supposed to do just
> that. There is an article at
>
> http://www.keepmedia.com/pubs/BroadcastEngineering/2004...
>
> but it requires registration. Other links have been posted before.
>
> Pat
>
>
The 5th gen receiver does improve reception and the developers of the
technology do admit to learning from COFDM.

And these receivers do take advantage of the multipath signals to
enhance reception but they do not do it in the same "rake" fashion.
COFDM is still far superior to both 8-VSB and cell technology. Far more
efficient for one thing.

And while 5th gen receivers are plug and play they are far inferior to
even 1999 COFDM. They are still easily defeated with both static and
dynamic multipath.
Anonymous
October 9, 2004 12:25:14 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

"Bob Miller" <robmx@earthlink.net> wrote in message news:S2b9d.5040
> The 5th gen receiver does improve reception and the developers of the
> technology do admit to learning from COFDM.
>
> And these receivers do take advantage of the multipath signals to
> enhance reception but they do not do it in the same "rake" fashion.
> COFDM is still far superior to both 8-VSB and cell technology. Far more
> efficient for one thing.
>
> And while 5th gen receivers are plug and play they are far inferior to
> even 1999 COFDM. They are still easily defeated with both static and
> dynamic multipath.

Now, I know I'm not supposed to feed the trolls, but assuming COFDM is so
superior, could you give me a clear, concise idea of what I can do to help
save our HDTV system from 8-VSB hell? For example, "Write your
congressman", "Write the FCC", "Boycott current HDTV hardware", "Picket in
front of the Federal building", "Join Al Quaeda", etc. Forgive me if you've
already mentioned the solution somewhere, but all I've soaked in so far is
that you REALLY like COFDM and many people seem be annoyed by your
enthusiasm.
Anonymous
October 9, 2004 10:18:44 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

M Schmidt wrote:
> "Bob Miller" <robmx@earthlink.net> wrote in message news:S2b9d.5040
>
>>The 5th gen receiver does improve reception and the developers of the
>>technology do admit to learning from COFDM.
>>
>>And these receivers do take advantage of the multipath signals to
>>enhance reception but they do not do it in the same "rake" fashion.
>>COFDM is still far superior to both 8-VSB and cell technology. Far more
>>efficient for one thing.
>>
>>And while 5th gen receivers are plug and play they are far inferior to
>>even 1999 COFDM. They are still easily defeated with both static and
>>dynamic multipath.
>
>
> Now, I know I'm not supposed to feed the trolls, but assuming COFDM is so
> superior, could you give me a clear, concise idea of what I can do to help
> save our HDTV system from 8-VSB hell? For example, "Write your
> congressman", "Write the FCC", "Boycott current HDTV hardware", "Picket in
> front of the Federal building", "Join Al Quaeda", etc. Forgive me if you've
> already mentioned the solution somewhere, but all I've soaked in so far is
> that you REALLY like COFDM and many people seem be annoyed by your
> enthusiasm.
>
>
Now that we have 5th gen receivers on the way I don't think you can do
anything to save the US from 8-VSB hell. They are minimally acceptable
so we are stuck with them and 8-VSB.

The power in this equation are the broadcasters. The NAB. They pull all
the strings in DC as you may have seen in just the latest joust between
the head of the Senate Commerce Committee, McCain, and the head of the
NAB. McCain was all but publicly humiliated by the ease with which the
NAB eviscerated McCain's bill.

Now there is spectrum in the US that can use COFDM and some of it has
been sold and will soon be put to use. Radio is starting to learn just
how competitive COFDM is. Both Sirius and XMRadio use COFDM
terrestrially and don't kid yourself that they are satellite services.
The satellite part is just an excuse to build a new terrestrial digital
radio service. When the public finds out how superior COFDM is and
broadcasters find themselves unable to compete with new players because
of 8-VSB you will see just how fast the US modulation will be changed.

And I might add with flagrant disregard to even multi millions of 8-VSB
receivers in the field. Congress will change the modulation to COFDM
overnight.

Or maybe you haven't noticed how such power brokers as the drug industry
simply has its way with our government lately. Their power is so great
and they feel so cocky they don't seem to even worry about incredibly
bad publicity.

And broadcasters are even more powerful than the drug industry IMO.
Anonymous
October 11, 2004 1:51:58 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

Remember, anything that Bob Miller says, the exact opposite is true.

-- Mark --

http://staff.washington.edu/mrc
Science does not emerge from voting, party politics, or public debate.
Si vis pacem, para bellum.
Anonymous
October 11, 2004 11:07:16 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

"Mark Crispin" <mrc@CAC.Washington.EDU> wrote in message
news:p ine.LNX.4.62.0410102150320.18903@shiva1.cac.washington.edu...
> Remember, anything that Bob Miller says, the exact opposite is true.
>
> -- Mark --
>
> http://staff.washington.edu/mrc
> Science does not emerge from voting, party politics, or public debate.
> Si vis pacem, para bellum.

Perhaps as a compliment to Bob's response to me, you could tell me whether
your view then is that COFDM is a) not superior to 8-VSB, b) superior maybe,
but the "Betamax" of modulation schemes, or c) something completely
different.
October 11, 2004 11:16:31 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

"M Schmidt" <martinschmidt57@hotmail.com> wrote in message
news:Eiqad.17$6k2.10@newsread3.news.pas.earthlink.net...
> "Mark Crispin" <mrc@CAC.Washington.EDU> wrote in message
> news:p ine.LNX.4.62.0410102150320.18903@shiva1.cac.washington.edu...
>> Remember, anything that Bob Miller says, the exact opposite is true.
>> -- Mark --
>> http://staff.washington.edu/mrc
>> Science does not emerge from voting, party politics, or public debate.
>> Si vis pacem, para bellum.
>
> Perhaps as a compliment to Bob's response to me, you could tell me whether
> your view then is that COFDM is a) not superior to 8-VSB, b) superior
> maybe,
> but the "Betamax" of modulation schemes, or c) something completely
> different.


You'll be able to learn the fundamental realities about COFDM by doing a
google/groups search, using the search terms "Bob Miller" and "liar".
Anonymous
October 11, 2004 3:56:37 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

M Schmidt wrote:
> "Mark Crispin" <mrc@CAC.Washington.EDU> wrote in message
> news:p ine.LNX.4.62.0410102150320.18903@shiva1.cac.washington.edu...
>
>>Remember, anything that Bob Miller says, the exact opposite is true.
>>
>>-- Mark --
>>
>>http://staff.washington.edu/mrc
>>Science does not emerge from voting, party politics, or public debate.
>>Si vis pacem, para bellum.
>
>
> Perhaps as a compliment to Bob's response to me, you could tell me whether
> your view then is that COFDM is a) not superior to 8-VSB, b) superior maybe,
> but the "Betamax" of modulation schemes, or c) something completely
> different.
>
>
Hard to equate either 8-VSB or COFDM to Betamax. COFDM unlike Betamax is
a worldwide success story having been adopted by most of the world for
digital TV including Japan (ISDB-T), Europe (DVB-T, DVB-H, DAB), China
(DMB-T), S. Korea (DAB, DVB-H) and most other countries (DVB-T, DVB-H
and DAB).

8-VSB has been adopted by the US where it was bitterly fought by some
broadcasters and where COFDM was supported by many broadcasters and
computer companies and the Department of Defense. 8-VSB was adopted by
Canada because they have a long border with the US and while their
broadcasters were pro COFDM their government overruled them. Nothing
much has happened in Canada since their choice of 8-VSB years ago.

Mexico recently chose 8-VSB after much negotiation (read bribery) and
will do even less than Canada. Mexico made its choice only after being
informed of the 5th gen receiver technology. S. Korea had a REVOLT among
its broadcasters who refused to put 8-VSB on the air ever since 1998
when it was chosen as the countries DTV modulation standard. They
recently gave in after the introduction of 5th generation receivers and
after their government agreed to allow COFDM to be used for mobile DTV
ventures.

Other countries actually SWITCHED from 8-VSB to COFDM. They include
Australia and Taiwan. Argentina chose 8-VSB but then switched to a
neutral position with NO choice of a digital modulation.

COFDM is being used and is superior for HDTV. It is used in Australia,
Japan and soon France. It has a higher data rate than 8-VSB at 19.76
Mbps and at that speed is still more robust. That is you can still
receive COFDM mobile at that data rate. 8-VSB is stuck as 19.34 Mbps and
is easy to defeat with both static and dynamic multipath at that datarate.

That said after almost 7 years 8-VSB finally has been able to field a
minimally acceptable 5th generation receiver so it will limp along for
some time in the few countries stuck with it.
Anonymous
October 15, 2004 1:57:18 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

"M Schmidt" <martinschmidt57@hotmail.com> wrote in message
news:Eiqad.17$6k2.10@newsread3.news.pas.earthlink.net...
> "Mark Crispin" <mrc@CAC.Washington.EDU> wrote in message
> news:p ine.LNX.4.62.0410102150320.18903@shiva1.cac.washington.edu...
>> Remember, anything that Bob Miller says, the exact opposite is true.
>>
>> -- Mark --
>>
>> http://staff.washington.edu/mrc
>> Science does not emerge from voting, party politics, or public debate.
>> Si vis pacem, para bellum.
>
> Perhaps as a compliment to Bob's response to me, you could tell me whether
> your view then is that COFDM is a) not superior to 8-VSB, b) superior
> maybe,
> but the "Betamax" of modulation schemes, or c) something completely
> different.

Sorry there are people on this NG that bash Bob regardless of how many facts
he uses to backup his view. They would have you believe that Bob is just
wrong for no particular reason, and that should be good enough for you.

I think Bob is just adamant about those views, and perhaps those people are
just tired of reading them. Perhaps they have other motivations.

??
Anonymous
October 16, 2004 9:27:43 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

In article <ckol01$12ju$1@spnode25.nerdc.ufl.edu>,
"John Doe" <me@here.com> writes:
>
> "M Schmidt" <martinschmidt57@hotmail.com> wrote in message
> news:Eiqad.17$6k2.10@newsread3.news.pas.earthlink.net...
>> "Mark Crispin" <mrc@CAC.Washington.EDU> wrote in message
>> news:p ine.LNX.4.62.0410102150320.18903@shiva1.cac.washington.edu...
>>> Remember, anything that Bob Miller says, the exact opposite is true.
>>>
>>> -- Mark --
>>>
>>> http://staff.washington.edu/mrc
>>> Science does not emerge from voting, party politics, or public debate.
>>> Si vis pacem, para bellum.
>>
>> Perhaps as a compliment to Bob's response to me, you could tell me whether
>> your view then is that COFDM is a) not superior to 8-VSB, b) superior
>> maybe,
>> but the "Betamax" of modulation schemes, or c) something completely
>> different.
>
> Sorry there are people on this NG that bash Bob regardless of how many facts
> he uses to backup his view.
>
I agree that criticism against Bob's claims is sometimes strong, but given
human feelings (people simply get tired of the misleading claims), it would
be expected that Bob would be a lightening rod for criticism.
Firstly, I have WANTED to like Bob, and have tried to take up for him
in a few cases, even against people in this group who I believe that I'd
like if I met them. Bob is not always a liar, but I do believe that he
is misguided, and sometimes really believes some of his wrong (or
distorted) claims. Some of Bobs' facts are correct, however seem often
to be deceptively mixed with odd, eccentric or totally wrong claims.
I DO NOT WANT TO DISLIKE OR DISTRUST BOB. In fact, I cannot say that
I dislike him -- he deals with aggressive criticism rather well, and
appears to be very used to it. I wish Bob would quit trying to justify
COFDM. (Previously, I told people that 8VSB receivers would get better
(where Bob would poo-poo them), and now Bob talks about the new receivers,
but seems to assume that they'll never get better yet. I make the claim
now that some time in the future, the 8VSB receivers will be BETTER yet,
when they need to be. If they dont' get much better, it will be because
the current (newest generation) receivers are GOOD ENOUGH in the stationary
reception situation. The moving TV viewing situation is best solved
by pre-recorded media, because in the US there is no motivation and
almost no consumer market for VOLUNTARY MOVING RECEPTION OF TV -- that is,
in the case where the consumer would likely turn on the TV to view
the show.

Secondly, based upon Bob's claims, I have spent more money than need be.
I have learned that it is unwise to take his claims as totaly trustworthy.
My mistake, as a very experienced engineer who now works at a major
TV manufacturer, was to take his claims at face value (assuming
that Bob's integrity and ethics were just like mine), and realizing
that when I was reading Bobs' claims, I hadn't looked much at HDTV for
10yrs. I happily defer to authority, but from ignorance, I deferred
to Bob instead.

Sometimes, Bob has been known to spin the facts in a way to distort their
meaning. Such spin would certainly include ignoring the context of the
results and also totally leave out the substance of his quoted facts. For
example, it is well within a Bob claim to leave out a caveat (something
like ignoring the fact that the payload isn't HDTV or even HDTV bandwidth
for his beloved system.)

It is certainly true that almost all of Bobs desires would weaken HDTV
in the US (unless perhaps the TV stations were allocated 8MHz instead
of 6MHz), yet he also sometimes inconsistently claims that he likes
HDTV, yet has also said that 480p is all that the customer needs.

Someone has alleged that Bob has (from second hand info) on his website
advocated the possibility of advertisements on mass transit. When providing
moving video, with either COFDM or 8VSB WITH THE 6MHz US allocation, a good
choice would be to assume 2mbps or higher payload for moving video that
provides an apparent undistorted and unartifacted quality. Given 8VSB can
carry approx 19mbps, but below 15mbps, 1080i tends to look more and more
heinous as the bitrate decreases, then there is ONLY the possibility of
providing TWO (perhaps three-four, with better compression techniques) moving
video tampon, condom, cigarette, and perhaps targeted ads to children during
school commutes. That non-video, fully unidirection transport applications
are definitely fairly weak while also destroying the quality of the HDTV
transmissions.

No matter how the standard is changed, there can be something better,
newer, more efficient in the future. For viewing HDTV at home (or
in fixed positions, like the beach, at picnic, or in a bar), then the
current scheme does work quite well. For watching HDTV in an SUV
while driving down the road, no OTA scheme other than a VERY COMPLETE
SFN scheme would be workable, however the US doesn't even have
an adequate scheme for viewing NTSC on the road -- because the
coverage of TV in the US IS NOT UNIVERSAL, especially when using
a practical antenna for an SUV while moving at 60mph. FRANKLY, THE
BETTER SCHEME IS TO USE DVD VIDEO that has been properly screened
for DRIVING DOWN THE ROAD ALL AROUND THE COUNTRY.

*** The SIGNIFICANT AND PRACTICAL use of mobile HDTV reception is
for saturation advertising that further and excessively pollutes
the already ugly environment that we often have to deal with. Normal
consumer mobile reception of HDTV (or even DTV) has a very limited
market, is second or third choice to a better solution, and would be
VERY VERY UNLIKELY to be adopted or even adoptable by most responsible
consumers because of practicality, safety and legal reasons. ***

John
Anonymous
October 23, 2004 6:24:33 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

John S. Dyson (toor@iquest.net) wrote in alt.tv.tech.hdtv:
> For watching HDTV in an SUV
> while driving down the road, no OTA scheme other than a VERY COMPLETE
> SFN scheme would be workable, however the US doesn't even have
> an adequate scheme for viewing NTSC on the road -- because the
> coverage of TV in the US IS NOT UNIVERSAL, especially when using
> a practical antenna for an SUV while moving at 60mph.

The truth of the matter is that the US doesn't even have complete cell-phone
coverage even in major metropolitan areas. If that can't be done when there
is *tons* of money in it, why would mobile HDTV ever work?

--
Jeff Rife |
SPAM bait: | http://www.nabs.net/Cartoons/Dilbert/LostNetworkPasswor...
AskDOJ@usdoj.gov |
spam@ftc.gov |
Anonymous
October 23, 2004 8:57:43 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Jeff Rife wrote:
> John S. Dyson (toor@iquest.net) wrote in alt.tv.tech.hdtv:
>
>> For watching HDTV in an SUV
>>while driving down the road, no OTA scheme other than a VERY COMPLETE
>>SFN scheme would be workable, however the US doesn't even have
>>an adequate scheme for viewing NTSC on the road -- because the
>>coverage of TV in the US IS NOT UNIVERSAL, especially when using
>>a practical antenna for an SUV while moving at 60mph.
>
>
> The truth of the matter is that the US doesn't even have complete cell-phone
> coverage even in major metropolitan areas. If that can't be done when there
> is *tons* of money in it, why would mobile HDTV ever work?
>
Very simply because the spectrum for TV is lower than that for cell phone.

Also the small matter that a cell phone network has to both SEND and
receive. That means the CELL PHONE has to have a transmitter in it that
is capable of transmitting all the way back to the tower.

Can you picture your cell phone having a million Watts of power so that
you can transmit to the Empire State building from the middle of New
Jersey? Can you imagine anyone comparing a two way cell phone network
coverage that uses microwatts to a one way broadcast DTV network that
uses MEGAWATTS and suggesting that there was any comparison of coverage?
You just did.

Cell phones are mobile. Our current television modulation is NOT capable
of mobile but every other modulation being used in the world is capable
of mobile.

MOBILE HDTV???? Mobile DTV you mean. HDTV is a resolution not a TV
system. Of course mobile DTV will work and therefore if someone wants to
deliver a resolution like HDTV that will work also. The is a business
decision, do we want to devote all those bits to one program or many.
The next thought becomes well most mobile screens will be small, why
would we want to deliver an HD resolution to minuscule screens?

Mobile DTV works, yes you have to build a comprehensive SFN to do it.
XMRadio has already done that for digital radio. They have 1500
terrestrial transmitters in major cities. The problem again for XM is
that they are using higher frequencies than normal TV does. And yet
potentially the first DTV mobile systems, Crown Castle's) for cell
phones will use 1.4 GHz (not quite so bad as XM's 2.4 GHZ).

They will have to build a VERY comprehensive SFN with small cells
because of their frequency allocation. But they will do it. Will they
deliver HD? Of course NOT. If they did would it work? Of course it would.

Using 700 MHz spectrum or lower (800 MHz down) and using a very
reasonable SFN network you can build a national DTV network that will
allow the reception of hundreds of programs while mobile at 100 mph in
your SUV or your Yugo with a built in (non-visible ) 3 inch antenna (or
even smaller).

Will it be HDTV? Not real time since I expect the bean counters are
going to want to make the most money they can and that will be more
programming not more resolution. But these mobile receivers will have
hard drives or other storage devices and the capacity of those devices
will grow rapidly over any number of years you paste into your business
plan. That means that non real time in off hours higher resolution
programming can be broadcast for auto storage on those devices for later
viewing.

How do you view those stored HD programs? With HD projectors that fit in
your pocket and can project onto any white surface. With HD glasses that
let you watch on the bus or subway or the back seat of the car and other
such devices which keep popping up. And on HD flat screen DTVs that will
find there way into mobile transport as well.
!