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TTY telephone number for DTV information, and more! [Telecom]

I was catching up with my reading of the local newspaper's comic strips (I'm up to 19 June), when I came across Jerry Romansky's column (in the same section of the newspaper as the comics). Christopher L. from Toms River, NJ wrote in with some information on recycling analog TVs. He also wrote "By the way, my hearing-impaired neighbor was thrilled with the information she received from the TTY number, 877-530-2634."

I've already spent our coupons on the DTV converter boxes. I researched the boxes, starting with and . Then I found the "Coupon Eligible Converter Box (CECB)" forum on , where I found out about the box I ended up getting, the Zenith DTT901.

The Zenith DTT901 was the only box (or at least the first box I found information about) that had good reports plus all the features that I wanted. It appears that the problems experienced with the previous model have been solved (hopefully) with the DTT901. Mine came from Circuit City, who had plenty when I got mine. One of the sales guys told me that the DTT901 is the only model that Circuit City is carrying now, that they no longer carry the previous model. Your mileage may vary.

I specifically wanted to get a box with the analog pass-through feature. We get fairly good analog TV reception where we live, and I wanted to be able to choose between analog or digital during this "overlap" period, just in case there were issues with digital reception. Also, I wanted to be able to setup each TV and box so that my wife would not have to do anything different if she wanted to watch TV.

We do have some issues with DTV (or at least with our specific DTV setup):

1) The signal strength for one or two channels is not quite good enough. I guess I'll have to start thinking about a better antenna. Or, according to one
formatting link
message I just read, maybe I should try a better cable from the box to the TV, first.

2) The amount of time from when you turn on the box to when you get picture and sound is annoying, since it's several seconds longer than just powering up the analog TV by itself. I deal with that by powering up the DTV box first, waiting a moment or two, then powering up the TV.

3) Also annoying is the delay for the picture and sound when you change channels on the DTV box, especially when you're used to no delay when changing channels when watching the analog TV without the box.

4) The blocky artifacts and pausing/jumping (when the DTV's station's signal strength is varying from good enough to not quite good enough) is annoying. With analog TV, the TV is still watchable even when the signal is not the strongest.

But, I will say that, from a telephone point-of-view, I'm glad that I don't have to connect these DTV converter boxes to my phone line!!!

Regards, TheLinuxFan

***** Moderator's Note *****

I have a Zenith box, and I realized very quickly that they're not very good without an outside antenna. DTV is not nearly as robust as the old analog system, which, for all its faults, _was_ useable in much more marginal conditions.

Digital TV needs an outside antenna, cable, or satellite. It's just not designed for marginal signal environments. That's not to say that the analog system was anything to brag about, but advances in receiver design and manufacturing over the years made it a lot more useable in frindge areas than the original vacuum-tube televisions ever could be.

However, the press of technology never slows: the same advances that made better analog sets possible have ushered in the digital age, and although the new system offers some advantages, I think on balance that its shortcomings outweigh them.

  1. As TheLinuxFan points out, the digital system takes longer to change channels and is prone to dropouts when users get it off-the-air. Cable or Satellite services will pick up a lot of customers who can't use "rabbit ears" or put up external antennas, thus forcing "free" TV users into the "pay forever" mode that the cable and satellite companies know and love.

  1. The transition will free up spectrum space which the government in the U.S. has and/or will auction off to the highest bidders.

  2. DTV will deliver movie-quality images to DTV receivers in homes, but this "advance" will benefit mostly the copyright owners of older movies, which are being endlessly recycled as their copy- rights near expiration. The new system offers the same aspect ratio used in moviemaking, thus easing the flow of movies from studio to movie house to TV, again benefitting movie studios who have seen their theater revenues plummet as users abandoned traditional venues in favor of "cocooning" around their home entertainment centers.

  1. The DTV system includes much more robust copyright protection, and although any system can be defeated, I think Hollywood is counting on DTV's "Digital Rights Management" features to keep copying down to a marginal cost.

  2. Billions will be spent on digital television receivers, and the recycling costs for analog sets have not been adequately addressed.

Long story short, DTV, like other digital technologies, is an "All or nothing" system, requiring better antennas, better receivers, and even cable or satellite service just so users can get the same talking heads and Gilligan's Island reruns. I feel that it has been pushed by a lot of hidden agendas, without adequate consideration given to how many of the costs have been pushed down to end users.

Bill Horne Temporary Moderator

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Reply to
telecomdigestreader.to.thelinu
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Just to pick a nit, but since the passage of the "Mickey Mouse Extension" of the Copyright Act, copyrights essentially never expire anymore. So much for the "limited time" provided to "authors and inventors" in exchange for promoting "science and useful arts" that the US Constitution provides.

Dave

Reply to
Dave Garland

I, too, find this very annoying. Every digital tuner I've seen (local cableco's digital set top box, satellite set top box) seems to have this... is this a basic attribute of digital tunes (necessitated, perhaps, by the digital modulation) or have I just been lucky enough to see only low-end tuners?

Our senses seem well equipped to compensate for slight analog degradation ('hissing', 'snow' on the screen, etc.), while digital receivers get completely lost and freeze or deliver incomprehensible sounds or patterns.

I agree with you, which is why I'm sticking with analog cable as long as my cableco offers it.

Reply to
Geoffrey Welsh

Yup. it _is_ an intrinsic part of the design. It's not that the signal is 'digital', but that the data stream is _compressed_. TV digital data streams are highly compressed, and you have to (a) wait for a synchronization mark so you know where the symbol boundaries are in the _bit_ stream, and (b) wait for the 'dictionary' of what the compressed tokens in the stream "mean" before you can map the tokens back to the 'original' pixel data.

The compression is done horizontally, vertically, *and* between successive frames. The last one is the primary culprit for the 'latency' in the new channel image display. It is also the one that gives the highest degree of compression and needs to use the same 'dictionary' for as long as possible.

Transmitting the dictionary, and/or sync markers, too often means losing the efficiency benefits of compression.

Reply to
Robert Bonomi

I suspected as much, and thanks for confirming it.

Way, way back I remember being told never to pipe the output from the tar command through compress on its way to tape because, if there's a data error, you'd never get sync back and the rest of the session would be lost. In stead, we compressed each file as we tarred it, allowing us to resync at the end of each file after a data glitch, just as you explain that compressed digital video must re-sync after a data error.

When compression came to dial-up modems, it seemed that it could only be enabled if an underlying error correction mechanism was in place; while this might have been due to dependency on facilities within the error correction protocol, it also seemed wise not to risk getting permanently out of sync on a continuous compressed stream due to a bit error!

It is intuitively obvious even to me that MNP- or V.42-style error correction is not possible on broadcast media, and I'm guessing that the overhead of forward error correction would be prohibitive, so I guess we just have to live with the artefacts. (Or with analog signals, if we can obtain them.)

Not that forward error correction could speed up a resync if I flip to a new channel in the middle of a "block" of data...

Thanks,

Reply to
Geoffrey Welsh

It's not so much that it's not possible, it's not worthwhile. The worst that'll happen is that you'll get a picture glitch.

The reason that video compression introduces delay is that the compression technique such as MPEG send the frames out of order, with occasional full frames in JPEG format, and then much smaller delta frames that interpolate between the last two full frames sent. The more you do this, the more compression you can do, but the out of order part means that you need to have enough of a buffer to put the frames back in order.

R's, John

Reply to
John Levine

Yup. 1000% true, DAMHIKT.

Same problem if you have a single error in a conventional compressed file written to disk. _nothing_ after the point where the error occurs is recoverable. Except by 'guessing' (usually brute-force enumeration of all the possibilities) what the mangled bits are 'supposed' to be (and *ASSUMING* you have some way of telling _how_many_ of them got mangled), and seeing if the decompressed result "makes sense".

*OR* the mayhem that ensued, back in the days of PCs, MS-DOS, and the various 'compressed' (e.g., "Stac", "DoubleSpace", etc.) _filesystems_ used to compensate for the high price, and architectural size limitations, of the hard-disk drives of the day. Have the disk develop an additional 'bad sector', and there was a very real risk of having _all_ the data on the entire drive become 'unreadable'/'unrecoverable'.

Yup, the actual 'tape mark' on the tape, occurring between data-sets, could not possibly occur in user data, so it was an 'identifiable' starting point;

*knowing* you were 'at the beginning' told you how to start parsing the data stream.

Basically, it made the implementation simpler, a _LOT_ simpler, by dealing with the stuff in a layered fashion. you could use `conventional compression techniques -- ones that "assume" a reliable infrastructure -- and then just deal with the reliable structure without being concerned with what type of data you were passing.

Otherwise, you would have had to build FEC and/or ECC into the compression protocol, *plus* synchronization markers for re-start points.

One other compelling reason for the 'layered' approach -- it made _testing_ and _troubleshooting_ a *WHOLE* lot easier.

The effectiveness of FEC, as well as 'conventional' ECC, depends almost entirely on 'what you're willing to pay' -- in terms of 'overhead bits' per bit of 'actual data' -- to achieve any particular level of error "tolerance".

Contemporary Satellite TV uses a fairly 'expensive' amount of FEC. I'm pretty sure that over-the-air HTDV does use FEC, also. The 'frozen' images, and/or large-block pixilation you occasionally see are one result of an error that is 'bigger' than the FEC bits can 'forward correct' for.

Once people get 'used to' the "perfect" images from the digital transmissions, only a _microscopic_ minority will be willing to put up with the flaws of the current Depression-era technology.

Obviously true, but even _THAT_ doesn't occur to a lot of people.

Reply to
Robert Bonomi

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