ATSC to QAM modulator - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 11 Old 11-20-2019, 02:24 PM - Thread Starter
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ATSC to QAM modulator

Hi

I wanted to convert over the Air Signals to QAM and amplified and distribute to 50 TVS (if I do with same ATSC then last tv get only noise amplified and that's the reason I need to convert it to QAM.

If any help on this

1) what type of cost effective Equipment
2) Source of this Equipment and other information

If any other way then I am thinking please let me know

Thanks
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post #2 of 11 Old 11-20-2019, 02:36 PM
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I've used Blonder Tongue AQTs before for single channels, way back:
https://www.tonercable.com/pdf/AQT_U...651219100C.pdf

...but it seems they only make an 8-channel model now:
https://www.blondertongue.com/aqt8-qam-ip.html

There are plenty of options, but that should give a start to find comparable from whichever manufacturer you'd like. The link above shows one source, but you may have vendors that can get you your model-of-choice from a cheaper distributor. Really not sure what kind of budget you're looking at, as this is usually Commercial or MDU equipment and pricing.
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post #3 of 11 Old 11-20-2019, 06:34 PM
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Quote:
Originally Posted by Gitesh Pandya View Post
Hi

I wanted to convert over the Air Signals to QAM and amplified and distribute to 50 TVS (if I do with same ATSC then last tv get only noise amplified and that's the reason I need to convert it to QAM.

If any help on this

1) what type of cost effective Equipment
2) Source of this Equipment and other information

If any other way then I am thinking please let me know

Thanks
Why are you certain that your distribution will work better with QAM than with ATSC?

Are their other factors?
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post #4 of 11 Old 11-21-2019, 04:49 AM
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More accurate.... QAM vs. 8VSB.



If you can’t explain it simply, you don’t understand it well enough – Albert Einstein
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post #5 of 11 Old 11-21-2019, 06:21 AM - Thread Starter
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Quote:
Originally Posted by Channel99 View Post
Why are you certain that your distribution will work better with QAM than with ATSC?

Are their other factors?
Distance between TVs and number of TVs I wanted to connect 120 TVs with it each splitter loss of 7db even though I will distribute the load 24 x 5 so each 25 splitter has loss of DB and If I amplified those signals to 25*7 = 175 loss only in split between so ultimately tvs will get amplified noise.

If I convert those in QAM then noise amplification will be very less or null and my end TV will get full list of channels

Hope I make things clear with my limited knowledge of AVS.

Thanks
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post #6 of 11 Old 11-21-2019, 08:53 AM
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QAM and 8VSB are modulation techniques to carry an ATSC signal. Why would/does one have different "loss" from the other?
(Not a challenge... a question.)


My thought... your concern should be cable type, cable distances/runs, placement of splitters and/or signal regeneration (distribution amps). I think this is more important than modulation types.
In other words... a good cable plant design for the least amount of signal loss/degeneration, whether QAM or 8VSB.



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post #7 of 11 Old 11-21-2019, 11:00 AM - Thread Starter
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Quote:
Originally Posted by Ratman View Post
QAM and 8VSB are modulation techniques to carry an ATSC signal. Why would/does one have different "loss" from the other?
(Not a challenge... a question.)


My thought... your concern should be cable type, cable distances/runs, placement of splitters and/or signal regeneration (distribution amps). I think this is more important than modulation types.
In other words... a good cable plant design for the least amount of signal loss/degeneration, whether QAM or 8VSB.
Can you please guide me about selecting cables distance between first point to last of TV (set of 24 ) is 75 Feet and every 12 feet we have splinters four way spliters and from there on we going to end of last branch.

Again I don't have any knowledge of loss of signal what I learn from other tech guys informed me this loss or gain go noise theory
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post #8 of 11 Old 11-21-2019, 11:10 AM
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I can't provide a design recommendation. I have no idea/concept about the facility and anticipated desires.
Best guess???? Add a distribution amp every 25-30 feet?


You should probably consider a "professional" contractor.



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post #9 of 11 Old 11-21-2019, 12:16 PM
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Quote:
Originally Posted by Gitesh Pandya View Post
Hi

I wanted to convert over the Air Signals to QAM and amplified and distribute to 50 TVS (if I do with same ATSC then last tv get only noise amplified and that's the reason I need to convert it to QAM.

If any help on this

1) what type of cost effective Equipment
2) Source of this Equipment and other information

If any other way then I am thinking please let me know

Thanks
Hello, Gitesh


First you must have the proper distribution system.
Quote:
Can you please guide me about selecting cables distance between first point to last of TV (set of 24 ) is 75 Feet and every 12 feet we have splinters four way spliters and from there on we going to end of last branch.
For that type of system you should use a high level trunk line with directional couplers, also called taps. As the signals get weaker down the line, the loss of the tap is reduced to compensate for that reduction of signals so that all TVs have about the same strength signals. This arrangement will work better than all splitters.

At each location you can use a 4-way directional coupler or a single tap coupler and a 4-way splitter.

The end of the trunk line must be terminated with a 75 ohm resistor.
Quote:
2) Source of this Equipment and other information
The source of the equipment depends upon where you are located. What is your location?

If you don't have a meter to measure the strength of the signals, I agree with Ratman; you should have a professional contractor do the installation for you.

Once you have a good distribution system, then you can use either 8VSB ASTC signals or QAM SCTE (Society of Cable Telecommunications Engineers) signals.

If you want to use QAM, you will need a tuner and a modulator for each channel. How many ATSC OTA channels do you have to be converted to QAM for the system?

If you can not measure it, you can not improve it.
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Last edited by rabbit73; 11-21-2019 at 12:21 PM.
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post #10 of 11 Old 11-21-2019, 12:38 PM
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Quote:
Originally Posted by rabbit73 View Post
If you want to use QAM, you will need a tuner and a modulator for each channel.
Unless all 50 or 120 TV's will all be displaying the same OTA channel simultaneously.
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post #11 of 11 Old 11-21-2019, 02:41 PM
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To the OP...
Is this for a retail display setup to demonstrate 50/120 TV's?
Is this for a very large sports bar or similar venue?
Is this for a condo/apartment/motel complex?


So many questions from us... need more info from you. (Which is without a fee. )
Dentists get paid for pulling teeth.
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