[opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV
- From: "John Willkie" <johnwillkie@xxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 8 Aug 2008 08:52:31 -0700
Are you merely drunk in the A.m.?
How can you even start to equate the Australian regulatory environment --
forced multicasts -- with the U.S. one, where broadcasters are basically
free?
And, you use it as a reason to criticize M/H. There is nothing to make
broadcasters simulcast with M/H, and there will never be. They are free to
multicast, simulcast, or even use the features of M/H that will never be
coming to a fixed television set near you.
Here's another thing for you to think about over your morning cup of
something: modulation isn't particularly important. The same basic
ipairments of 8-vsb and DVB-T are addressed, respectively, by M/H and T2/h.
There are limits to modulation, and there are work-arounds. You think the
workarounds mean the only way to compare is to go back a few generations.
How's that working out for you? Have you ever deployed a transmitter and
put it into service? I mean, other than loaners from vendors?
John Willkie, who has no problem with being accused by Mark Aitken about m/h
rf subsystem; I am only paying attention to the systems layer.
-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Bob Miller
Enviado el: Friday, August 08, 2008 3:48 AM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV
And I might add 20%, 10% or 36% efficiency to delivery REDUNDANT
programming to make sure viewers can receive the signal in challenging
locations. Something that Australia has been criticized for. Australia
triplecast in SD analog, SD digital and HD digital but they do NOT do
it because the main HD digital program cannot be received reliably and
they do NOT do it so that the HD program can be received mobile.
Neither of those problems needs to be addressed in Australia.
AFAIR they did it so as to minimize the cost of SD receives at a time
when Australia thought that receivers would be very expensive for
either SD or HD and more so for HD and they were worried whether ANY
manufacturer would make any receiver at all at any price.
Reception was not the issue.
In the US we are opting to do REDUNDANT broadcasting to solve the
mobile and reception issues which don't even exist with better
modulations. And IMO this new service is NOT compatible with and
breaks all legacy receivers if either the legacy receivers cannot
receive the new services at all or cannot receive the new services
because they will use MPEG4.
Can you imagine suggesting that part of the 19.34 Mbps that 8-VSB is
capable of were to be used with DVB-T and MPEG4 say in 2000? What
would be the arguments against?
First it can't be done.
Second that legacy receivers, all 2000 of them, could not receive the
DVB-T service, never mind that a broadcaster like Sinclair offered to
replace any 8-VSB receiver with a DVB-T receiver.
Third that legacy receivers can't decode MPEG4.
In my ignorance I think I actually asked that question in 2000.
How times change.
OH!! Then there was that thing about DVB-T not being as efficient as
8-VSB. Something about DVB-T only being capable of 18.6 Mbps while
8-VSB could handle a whopping 19.34 mbps.
At that time .74 mbps was too much to sacrifice for decent and mobile
reception. And making 2000 8-VSB receivers obsolete was a big deal.
Now 9 mbps is OK and millions of receivers being denied access to that
9 mbps is OK so that a measly .9 mbps of REDUNDANT programming can be
received mobile.
How times change.
The worst of all worlds.
Bob Miller
On Fri, Aug 8, 2008 at 6:26 AM, Bob Miller <robmxa@xxxxxxxxx> wrote:
> This is getting more confusing. According to John you need 9 mb/s for
> two services regardless of whether you are using 1/2 on one and 1/4 on
> the other?
>
> The article says they are using a total of 4.5 mb/s with one service
> at 1/2 using .6 mb/s and the other service at 1/4 using .3 mb/s. Mark
> says the efficiencies are 18% for 1/4 and 36% for 1/2. If .3 mb/s is
> 18% efficient then 100% is 1.67 mb/s and if .6 mb/s is 36% efficient
> then 100% would be 1.67 mb/s for a total of 3.34 mb/s.
>
> 3.34 mb/s is 1.16 mb/s shy of 4.5 mb/s and if John is right and you
> need 9 mb/s for two services it is 5.66 mb/s shy.
>
> If John is right then for .9 mb/s of programming you need 9 mb/s of
bandwidth.
>
> I don't think I ever thought it would be that bad.
>
> If Tom is right as to the article they needed or at least 4.5 mb/s to
> transmit .9 mbps or a 20% total efficiency.
>
> If John is right they would need 9 mb/s for the two services totaling
> .9 mb/s for an efficiency of 10%,
>
> What am I getting wrong? What don't I understand? Was I wildly
> optimistic last year?
>
> Bob Miller
>
>
> On Fri, Aug 8, 2008 at 2:10 AM, John Willkie <johnwillkie@xxxxxxxxxxxxx>
wrote:
>> You cannot draw conclusions until the standard has been released.
However,
>> I believe that public prints have put the o/h at close to 4.5 mb/seconds
for
>> one service, and IIRC, 9 for 2 services. Maybe the term isn't exactly
>> services, but I can only refer to things which have been mentioned
publicly.
>>
>> John Willkie
>>
>> -----Mensaje original-----
>> De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
>> nombre de Bob Miller
>> Enviado el: Thursday, August 07, 2008 9:09 AM
>> Para: opendtv@xxxxxxxxxxxxx
>> Asunto: [opendtv] Re: From Broadcast Engineering - WRAL tests mobile DTV
>>
>> That is what I would like to know. How far was I off last year when in
>> technical ignorance but from a good source I put out numbers on what
>> one 8-VSB mobile modulation would cost in bits. What are the numbers?
>> What is the overhead and what is the % of bits that are real at what
>> robustness levels?
>>
>> Anybody care to compare to DVB-T or H or CDMB-T or is it a big secret
>> because it is so bad.
>>
>> Bob Miller
>>
>> On Thu, Aug 7, 2008 at 11:24 AM, <dan.grimes@xxxxxxxx> wrote:
>>>
>>> What is the reason for only getting one 600 Kb/s and one 300Kb/s channel
>> out
>>> of 4.5 Mb/s? Are the rest of the bits required for overhead or did they
>>> just not fill all the M/H channels possible in the 4.5 Mb/s subchannel
>>> bandwidth?
>>>
>>> Dan
>>>
>>>
>>>
>>> Tom Barry <trbarry@xxxxxxxxxxx>
>>> Sent by: opendtv-bounce@xxxxxxxxxxxxx
>>>
>>> 08/06/2008 08:41 PM
>>>
>>> Please respond to
>>> opendtv@xxxxxxxxxxxxx
>>> To
>>> opendtv <opendtv@xxxxxxxxxxxxx>
>>> cc
>>> Subject
>>> [opendtv] From Broadcast Engineering - WRAL tests mobile DTV
>>>
>>>
>>>
>>>
>>> Supposedly from Broadcast Engineering though I copied it from AVS
>>> <http://www.avsforum.com/avs-vb/showthread.php?t=1056025>. I'm not sure
>>> I understand it correctly but it looks like they got a total of 900
>>> kbps (2 channels, 300+600) after error correction overhead from using a
>>> total of 4.5 mbps of the channel bandwidth.
>>>
>>> - Tom
>>>
>>> ---------------------------------------------------
>>> From Broadcast Engineering - WRAL tests mobile DTV
>>> Broadcast Engineering Mobile TV Update
>>>
>>> WRAL tests mobile DTV
>>>
>>> Users in Raleigh-Durham reported reliable signal reception in most parts
>>> of the station's existing coverage area.
>>>
>>> WRAL-DT, the CBS affiliate in Raleigh-Durham, NC, owned by Capitol
>>> Broadcasting Company (CBC), conducted a series of mobile DTV tests last
>>> week using the Mobile-Pedestrian-Handheld (MPH) system promoted by
>>> Harris Broadcast and others. Hosted by CBC's New Media Group, the tests
>>> featured seven handsets given to station executives living in different
>>> parts of the state. Users reported reliable signal reception in most
>>> parts of the station's existing coverage area.
>>>
>>> To kick off the July 21-25 trial, the station hosted a reception last
>>> Tuesday in which about 50 participants were driven in a bus around the
>>> area with prototype LG Electronics mobile handsets that featured
>>> MPH-compatible reception chips inside. Signal reception of two channels
>>> (half rate at 600kb/s and one-quarter rate at 300kb/s) using about
>>> 4.5Mb/s (including turbo coding) of the station's 19.4Mb/s on-air DTV
>>> stream was reportedly strong everywhere they went during the 10-minute
>>> ride - even at 70 miles per hour.
>>>
>>> The goal of the service, according to John Harris, WRAL's director of
>>> programming, is to extend the reach of the station's television channel,
>>> and make it available everywhere our viewers are. The initial plan is to
>>> simulcast the on-air DTV signal. WRAL-TV broadcasts CBS network and its
>>> own local programming in the 1080i HDTV format as well as in SD digital.
>>>
>>> "We're excited about the possibilities," John Harris, WRAL's director of
>>> programming, told Broadcast Engineering. "The priority is to offer
>>> WRAL's TV signal in another way, in another place. I took one [handset]
>>> east of the station and I just kept driving until the signal dropped
>>> out. I got pretty far before that happened, so I can see the potential
>>> of this service."
>>>
>>> LG Electronics, Zenith Electronics and Harris, all proponents of the MPH
>>> scheme, helped out with the field trials. WRAL-DT uses a Harris Sigma
>>> CVD UHF transmitter, with an MPH module, for the weeklong test.
>>>
>>> In a statement, James F. Goodmon, CEO of CBC, said "mobile DTV
>>> broadcasting enables WRAL to better serve our viewers, communities, and
>>> advertisers by providing a strong combination of anywhere access,
>>> two-way communication, and mobility."
>>>
>>> In 1996, Harris worked with WRAL-DT as one of the first DTV stations in
>>> the country. Two years later, when John Glenn made his historic return
>>> to space, Harris worked with WRAL to conduct the first live HDTV
>>> broadcast of a space shuttle launch to audiences nationwide. Now, the
>>> station is the first to promote mobile DTV service in the state of North
>>> Carolina. WRAL predicts that more than 200 million portable devices will
>>> be sold in 2008, although few if any will have the necessary MPH
>>> reception chips inside.
>>>
>>> WRAL-TV and Capitol Broadcasting Company are part of the Open Mobile
>>> Video Coalition (www.openmobilevideo.com), a nationwide group of
>>> broadcasters driving the deployment of mobile digital broadcast
>>> television. Commercial deployments are forecast for 2009. The group
>>> hopes to have an established standard available to broadcasters by the
>>> February 2009 analog shutoff date.
>>> --
>>> Tom Barry trbarry@xxxxxxxxxxx
>>>
>>>
>>>
>>>
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>>
>>
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