Does an ATSC RF modulator exist like we had for NTSC?

[croquetala]

In the analog days of Master Antenna Systems it was common to convert an off-the-air channel and rebroadcast it thru the system so that all nodes on the system could tune a "ghost free" analog picture by tuning the converted signal. Now that we have digital tv and HDTV is there hardware to convert HD source to an unused UHF channel that can be broadcast to all HDTV ready sets in the house and thus get HDTV by tuning the formerly unused UHF channel?

[akirby]

So you want to take an ATSC signal on channel 39 e.g. and re-broadcast it on a different channel (27 e.g.)?

What purpose would that serve other than perhaps to amplify the MATV signal on long runs? A good quality splitter(s) and pre-amp would probably accomplish the same thing. There's no way to process the incoming digital signal to make it better, and the TV doesn't care which channel you're using - PSIP will map it to the same virtual channel anyway.

I can see why you'd want to do this to distribute an ATSC signal to NTSC TVs e.g. but not for the situation you described.

[croquetala]

Thanks! You explain the difference...now here is what prompted my inquiry:

I want to input from my Dish Network HDTV receiver/recorder composite video or HDMI outputs to all the tv nodes on my MATV system. I want to modulate the output so that my HDTV equipped TVs on my MATV can receive and display HDTV. Is there software or hardware that can acomplish this?

[akirby]

When you said HD source and MATV I just assumed you were talking about OTA HD. The problem is the Dish receiver does not send out an ATSC signal. You'd basically need an ATSC transmitter that takes a HDMI Input and converts it to an ATSC signal over the existing coax. The other option is HDMI but that requires HDMI cable and probably wouldn't work over long runs or to more than 2 TVs.

In other words - no. You need a HD receiver for each TV unless you're talking about grabbing the OTA HD signals.

[herbdrake]

While NTSC and QAM modulators are available (the latter only from dealers in professional head-end equipment), ATSC modulators for applications such as yours are not and probably will not be for a long time. There are several reasons for this.

First, ATSC uses 8VSB modulation. That particular modulation scheme is not so hard to generate in itself, but the digital processing that takes place prior to modulation is very complex. That's because 8VSB has a lot of redundency. Not only does it have forward error correction (which QAM has), but it also has trellis encoding, which spreads packets out in time so that an impulse noise spike won't cause a drop-out. It was designed especially to resist the problems encountered in over-the-air transmission and the cost of doing all this is so high that only TV broadcasters can afford to purchase ATSC modulators.

Second, ATSC is designed for broadcast, not cable. Because of all the redundency in 8VSB, it is about half as efficient as QAM, which is used on cable systems. That is, it takes a whole 6-MHz physical channel for one ATSC DTV broadcast (which can broadcast one HDTV program and a few SDTV programs). The decoded DTV bitstreams from two ATSC receivers can fit into a single 6-MHz physical cable channel, so even if ATSC modulators were as cheap as QAM modulators, the cable industry would have no interest in using them.

That brings up no 3. Since ATSC is inefficient on cable and very complicated to generate, there is no market for a cheap chipset to generate it in the quantities needed for home entertainment. That's the reason that it is not likely to be available in that form for a very long time, if ever.

Now the good news. It is possible to purchase ATSC decoders, ATSC-to-QAM processors, and ATSC translators. They are intended for professional head-end markets, so they may not be affordable for a home system, but they are available. A translator does what you are trying to do -- it moves an ATSC channel to another channel -- either a broadcast or cable channel -- without actually decoding the bitstream and re-modulating. These devices are available from Blonder Tongue Laboratories (http://blondertongue.com) and the R. L. Drake Co. (http://rldrake.com).

[akirby]

A translator does what you are trying to do -- it moves an ATSC channel to another channel -- either a broadcast or cable channel -- without actually decoding the bitstream and re-modulating. These devices are available from Blonder Tongue Laboratories (http://blondertongue.com) and the R. L. Drake Co. (http://rldrake.com).

I don't understand why you would need a translator to simply move the signal from one channel to another. If you have a TV with ATSC tuner then it will tune the original channel just as well as the new one. And since your only source for ATSC is OTA then by definition you wouldn't have multiple stations using the same channel to begin with.

[croquetala]

When you said HD source and MATV I just assumed you were talking about OTA HD. The problem is the Dish receiver does not send out an ATSC signal. You'd basically need an ATSC transmitter that takes a HDMI Input and converts it to an ATSC signal over the existing coax. The other option is HDMI but that requires HDMI cable and probably wouldn't work over long runs or to more than 2 TVs.

In other words - no. You need a HD receiver for each TV unless you're talking about grabbing the OTA HD signals.

Thanks!!! No will do for now I will read HDTV Magazine and be patient. The hardware will come if not trumped by some kind of HDMI political cabal.

[Richard]

A translator is definitely not a solution for distribution of an A/V source which as I understand it is what croquetala is looking for... Great post, thanks for the in depth info and confirming this product still does not exist along with how unlikely it is that it ever will!

[kq6qv]

The real reason this hardware does not exist is that HDMI has a super high data rate. There is no cheap hardware fast enough to recompress it, and license agreements discourage any corporation from even thinking about trying to develop it. HDMI also has features that prevent it from connecting to an unlicensed device, and a license would not likely be granted for this application.

Actually the circuitry would be very similar to what a camcorder does, and the market for these is quite large, encompassing independent film makers and home movies. Camcorders are available that shoot 1440x1080 24p with good MPEG2 compression output to disk, USB, or IEEE 1394. A factor of 3 improvement will reach 1920x1080 60p, and the industry is working toward that.

Turning MPEG2 into ATSC is not hard. If cheap hardware for this is not available now it soon will be. But this will not help croquetala. -Ken

[DavidEC]

I hope that I am not breaking forum rules by using brand names here.. but it is my understanding that others also make like products:

suggestion one:
480i
Ce Labs 1001st Stereo Agile Rf Modulator
While not 'HD' you can feed the A/V signal into this box 'side squeezed' and using your TV's setting to stretched back out to wide-screen stereo.
Price about $70

suggestion two.. running a pair of CAT5 cables from your HDTV receiver (satellite/cable box) and using the component and coaxial digital signal and the following devices
CE LABS CAT5TX CAT-5 HD A/V TRANSMITTER & CE LABS CAT5RX CAT-5 HD A/V RECEIVER [would need two for two TV's]DISTRIBUTES HIGH-DEFINITION COMPONENT VIDEO WITH DIGITAL OR LEFT/RIGHT AUDIO OVER CAT-5 OR CAT-6 WIRE ; HIGH-BAND WIDTH TRANSMITTER SENDS SIGNALS 500 FT TO 2 DIFFERENT
Price for two set setup about $600.. since the above device does have loop through I guess you could try daisy chaining a few together to feed more remote sites the same signal?

Using the second suggestion.. I have read of companies that are now even making 'routers' that will allow you to connect more than one HDTV receiver and route the correct signal to the receiving set.. but the price of these routers that I have seen are a bit pricey right now.

I have seen HDMI version of suggestion two.. but it only handles a single remote TV for the same price.

--David