The Official AVS 'Mobile DTV' (M-DTV) Topic! - Page 7 - AVS Forum
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post #181 of 510 Old 09-23-2010, 07:49 PM
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It's been a while since I've done much reading on it, and I don't recall whether or not this is addressed in any way in the A153 ATSC documents (If so, can't find it with a quick look at the Candidate standards Docs I have handy from a couple of years ago) ---

But, everything I had read about the subject seemed to indicate a possible ~11 dB improvement in C/N TOV for M/H due to the additional Error coding and training signals ..... 4dB C/N TOV for A153 vs. ~15 dB for A53 ...

For example, See page 10 at following link, where it says, under "Additional Coding and Training signals on Mobile Streams" :

"Can receive approx. 4 dB C/N vs. 15 dB for standard ATSC" .....

http://www.sbe.org/documents/Integra...C_Schwartz.pdf

Given Ken H's and BDfox18Doe's results so far -- I wonder, Did it not quite work out that way, or do the Current M/H receivers have a really high NF or something?

Jeff
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post #182 of 510 Old 09-25-2010, 05:34 AM
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Quote:
Originally Posted by Nitewatchman View Post

Given Ken H's and BDfox18Doe's results so far -- I wonder, Did it not quite work out that way, or do the Current M/H receivers have a really high NF or something?

Ken H and bdfox18doe didn't go into much detail on how they arrived at their conclusions. A few dB here and there can be a little difficult to measure. The correct way to evaluate C/N would be with a variable attenuator with at least 1 dB steps. Otherwise, you're dependent on having some M/H capable station right at the 15 dB ATSC threshold to test with.

It also depends on the amount of error correction selected for the M/H stream. The 1/4 rate outer code will give the best C/N, but the 1/2 rate outer code will give less (somewhere in the 7.5 dB C/N range). How much coding are M/H stations using?

Finally, as you mention, the receiver design come into play. These are 1st generation receivers. How long did it take for regular ATSC demodulators to become mature?

Unfortunately, performance matters very much for the success of M/H. If it works no better than standard ATSC, it's pretty much doomed as a successful format. If these receivers are really sub-par, then their early introduction may be more harmful than helpful.

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post #183 of 510 Old 09-25-2010, 05:59 AM
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I evaluated the receivers the way a viewer would.. not with test equipment and attenuators..but by placing in the car, with the provided antenna stuck on the roof..and LISTENING to the audio as I drove my normal route to work...at any point..no further than 10 miles from the WCCB and WAXN transmitters. So far, I'm not impressed with the receivers I have tried in the car, both no name imports. Admittedly, not one of them is an LG..which is not yet available and I am awaiting one to try (as well as a few Dell NetBooks) to see how much better it is or is not.

Last I checked stations here are running 1/2,1/4,1/4,1/4 error correction..I did the math on adding additional error correction..the next step up required considerably more bandwidth to implement than I was willing to allocate.

Now.. I have a MediaFlo receiver.. and with their 7 transmitters here it does pretty good..but for $15 a month..no solid nationwide coverage..and FOX News on a 4" screen with heavy compression just doesn't cut it..Satellite radio for the audio only is a better option over Flo, at least for me.

Unless the cellular carriers implement ATSC M/H..and broadcaster have content better than Jerry Springer and Dr. Phil..Not sure it will succeed..and with the push by some now to add FM receivers to cell phones may complicate that.

Bob

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post #184 of 510 Old 09-27-2010, 10:11 AM
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Quote:
Originally Posted by jsmar View Post

I may be wrong, but I don't see how enhancement 1 would help in locking the signal if your antenna is not moving in relation to the transmitter. The enhancement is used to correct the small timing errors that occur due to the movement.

Don't you think atmospheric conditions can cause timing errors too? Of course. Not as bad as doppler shift of a moving car, but still present.
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Enhancement 2 would only be helpful if you are trying to receive the M/H programming of a particular broadcaster.

Yeah I knew that. My point was that if ATSC-12 is not coming in maybe I could switch over to M/H-12 instead, because it's more robust. The 416x240 image on my full sized television would be no worse than watching VHS tape or CD-V.
.

My Free TV streams 19 Mbps == 6000 GB/month per channel. No cellphone can do that. WHY kill off this excellent service??
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post #185 of 510 Old 09-27-2010, 11:22 AM
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Quote:
Originally Posted by theaveng View Post

BTW how did they come-up with 416? A simple 1/2 multiplier on a standard 704x480 image would yield 352 pixels across. I can't figure out where they got the 416 from.
.

All MH is widescreen with squarish rather than rectangular pixels.

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post #186 of 510 Old 09-27-2010, 06:30 PM
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Originally Posted by Trip in VA View Post

All MH is widescreen with squarish rather than rectangular pixels.

Okay but still doesn't explain how they got 416. If converting from a widescreen 1920x1080 source, you have to divide the vertical by 4.5 and the horizontal by 4.61538..... not really a convenient scaling.

IMHO it would have been consistent to apply the 4.5 factor in both directions, and choose 1920/4.5 == 426.

My Free TV streams 19 Mbps == 6000 GB/month per channel. No cellphone can do that. WHY kill off this excellent service??
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post #187 of 510 Old 09-27-2010, 06:46 PM
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Quote:
Originally Posted by theaveng View Post

Okay but still doesn't explain how they got 416. If converting from a widescreen 1920x1080 source, you have to divide the vertical by 4.5 and the horizontal by 4.61538..... not really a convenient scaling.

IMHO it would have been consistent to apply the 4.5 factor in both directions, and choose 1920/4.5 == 426.

MPEG-2 and H.264 coded resolutions have to be a multiple of 16.

Ron

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post #188 of 510 Old 09-27-2010, 08:54 PM
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So predictable. I knew somebody would say that, but ATSC-M/H is MPEG4 which does not have that limitation. It can do blocks of any size, not just 16-pixel wide blocks.

My Free TV streams 19 Mbps == 6000 GB/month per channel. No cellphone can do that. WHY kill off this excellent service??
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post #189 of 510 Old 09-27-2010, 09:26 PM
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Quote:
Originally Posted by theaveng View Post

So predictable. I knew somebody would say that, but ATSC-M/H is MPEG4 which does not have that limitation. It can do blocks of any size, not just 16-pixel wide blocks.

Considering I've been working in the compression industry for 17+ years, it's possible I have a deeper understanding of how things work.

H.264 can have smaller partitions (the smallest being 4x4), but it is still based on 16x16 macroblocks. From the H.264 specification paragraph 0.6.3:

As in previous video coding Recommendations and International Standards, a macroblock, consisting of a 16x16 block of luma samples and two corresponding blocks of chroma samples, is used as the basic processing unit of the video decoding process.

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post #190 of 510 Old 09-28-2010, 09:23 AM
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Alright I'm wrong. So adjusting my previus calculations:

1920/4.5 == 426. Then crop to 424 to preserve as much of the image as possible.

My Free TV streams 19 Mbps == 6000 GB/month per channel. No cellphone can do that. WHY kill off this excellent service??
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post #191 of 510 Old 10-12-2010, 03:44 PM
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LG DP570MH 7-Inch Portable DVD and Mobile DTV Now Available at Amazon..

Bob

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post #192 of 510 Old 10-12-2010, 08:54 PM
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Good catch, thank you for the post. I look forward to reading reviews of this. I wish we had a station transmitting this in my market. Here is the URL http://www.amazon.com/LG-DP570MH-7-I...6937722&sr=8-1
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post #193 of 510 Old 10-25-2010, 01:39 PM
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http://www.prweb.com/releases/MygoTV...web4689104.htm

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post #194 of 510 Old 10-25-2010, 05:09 PM
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Thank you for posting that. Since one good turn deserves another, here is the company URL http://www.mygotv.com/ It will be interesting to see how they advertise this, how well it performs, and how well it sells. I think the basic message to be spread is that not all areas have Mobile DTV. Some of these will be sold and then returned because people will not read that and/or understand that. My market does not have Mobile DTV yet. I am in the Minneapolis/Saint Paul MN area and we do not have any stations broadcasting ATSC-M/H yet. I am glad that they have both regular ATSC AND ATSC-M/H. I don't recall if the LG DP570MH has just ATSC-M/H or if it has both types of tuners.

It looks like they have some tuners with both and some with one or the other:

MYGOTV for both portable and mobile DTV capability: DMT336R, DMT335R, DMT270R.

MYGOTV for only portable TV capability: DPT170D+, DHT235D, DHT234D.

MYGOTV for mobile DTV tuner: DMT3BR.
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post #195 of 510 Old 10-25-2010, 05:47 PM
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Quote:
Originally Posted by Jim1348 View Post

Some of these will be sold and then returned because people will not read that and/or understand

Agreed.. also, returned by those who get one and say.."18-10 (M/H) works pretty good, but not 18-1 (Legacy ATSC)"

And no, the DP570MH does not have Legacy ATSC support.

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post #196 of 510 Old 10-25-2010, 08:30 PM
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I am also still wondering how long it will be until we see these receivers integrated into other devices. For example, Garmin has a GPS/DTV https://buy.garmin.com/shop/shop.do?pID=14807 in Italy. I think that would be pretty slick. For safety, it could offer TV audio only while in motion, but allow video when parked. Obviously, other popular devices are notebook and netbook computer, so I am anticipating that there will be USB devices http://www.twice.com/article/458765-...hp?rssid=20310 http://www.amazon.com/Coby-TV-Receiv.../dp/B003TJVP80 http://www.cobyusa.com/?p=prod&prod_...8&pcat_id=1012 soon. Also, with the popularity of tablets like the iPad, Dell Streak, Samsung Galaxy, and others it would seem like a popular convergence. I could certainly see people surfing the web on an iPad and having a Picture In Picture of a local M-DTV in the upper right corner. Of course, regular smartphones would seem like a popular platform as well.
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post #197 of 510 Old 10-31-2010, 12:05 PM
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Quote:
Originally Posted by theaveng View Post

I have problems getting VHF12 when the sun is up.

Could you post your tvfool info or maybe just your zip code. I want to learn about your VHF 12 problem. BTW, an FM trap helped my channel 12 problem.
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post #198 of 510 Old 10-31-2010, 01:40 PM
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Quote:
Originally Posted by bdfox18doe View Post

I found another M/H receiver that I have on the way to play with:

http://www.dealextreme.com/details.dx/sku.45315

One caution if you buy this tho: " Speed limit: 120km/h; in America: 60-70MPH/hour"


Has anyone tested the "LX-A8005" ?

Enjoy,
Keith
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post #199 of 510 Old 10-31-2010, 01:48 PM
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Has anyone tested the "LX-A8005" ?

Nope.. they charged me for the unit when I placed the order..after 4 weeks or so the order still had not been filled, so I canceled and got a refund.

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post #200 of 510 Old 10-31-2010, 01:51 PM
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Thank stinks..

I want to play with a unit, and this seems like the only
one that does not need a Computer ( ie: USB) and also
has an External Antenna port..

I'll keep looking...

Thanks,

Enjoy,
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post #201 of 510 Old 10-31-2010, 03:59 PM
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The MHDTV-1 meets your criteria. http://www.mhdtv.info/



Bob

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post #202 of 510 Old 10-31-2010, 07:33 PM - Thread Starter
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Quote:
Originally Posted by Jim1348 View Post

I am also still wondering how long it will be until we see these receivers integrated into other devices.

January 2011.

'Better Living Through Modern, Expensive, Electronic Devices'

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post #203 of 510 Old 11-14-2010, 09:21 AM
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It doesn't look like there will be much in time for Christmas 2010 for M-DTV choices.
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post #204 of 510 Old 11-20-2010, 10:51 AM
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Quote:
Originally Posted by Keith View Post

http://www.dealextreme.com/details.dx/sku.45315 ...
Has anyone tested the "LX-A8005" ?

I got this unit, and tested it this morning here on Long Island, NY,
I recieved the following ATSC-M/H TV MDTV Signals :

WPXN D31 - qubo - WPXN Ion Media
WNJU D36 - Telemundo - WNJU T47
WLNY D47 - Wlny Broadcast - WLNY MH1
WLNY D47 - *NO A/V* - WLNY MH2


but I dont receive .. as listed at http://www.rabbitears.info/market.php?request=atscmph...
WNBC 28 - News - WNBC Mobile

Enjoy,
Keith
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post #205 of 510 Old 11-20-2010, 11:29 AM
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First of all, thanks for confirming what's on WLNY's MH. I'd been wondering what they were doing with Mobile 55-2. Sounds like nothing.

Second, I've heard that WNBC's MH has been up and down. You might try again during the week or something.

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post #206 of 510 Old 11-22-2010, 01:36 PM
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Got the Dell ATSC M/H Netbooks today..now to get time to play..

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post #207 of 510 Old 11-22-2010, 03:02 PM - Thread Starter
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Quote:
Originally Posted by bdfox18doe View Post

Got the Dell ATSC M/H Netbooks today..now to get time to play..

Cool. Let us know what you think.

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post #208 of 510 Old 11-22-2010, 04:23 PM
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Quote:
Originally Posted by bdfox18doe View Post

Got the Dell ATSC M/H Netbooks today..now to get time to play..

What is the model number of that netbook?
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post #209 of 510 Old 11-22-2010, 05:26 PM
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It is a special run for OMVC members not yet publicly available.

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post #210 of 510 Old 11-22-2010, 05:39 PM
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Thank you for the reply. There really isn't a big hurry for me yet, since there does not appear to be any broadcasters in the Minneapolis-Saint Paul MN DMA that have announced that they will be offering this anytime soon. I had been told that KMSP may be interested, but only time will tell.

In the meantime, I have started focusing on the Sling Adapter for my Dish Network 722k receiver. I have an Android Garminfone and the Sling Adapter on order, so it is just a matter of time.

I have also been giving some thought to devices to watch TV on. I was thinking that the Dell, when it is available to the public. would be a great mobile device. With a built in ATSC-M/H, it would allow local terrestrial tuning and the Sling Adapter would allow remote satellite TV viewing. Sort of the best of both worlds!
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