Good TV signal. What tools do I need? - AVS Forum
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post #1 of 3 Old 07-21-2001, 01:09 PM - Thread Starter
Jym
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I am obsessed with getting the TV distribution system performing well through my house.

The system includes analog cable, 3 channel modulator and 13 TVs.

I am breaking down the problem into the following pieces

1) Verify Cable signal alone is good
2) Verify Modulator signal alone is good
3) Combine cable signal and modulator and make sure it is
good.
4) Distribute the signal through the house.

I need instruments and what I am looking for to complete this.

Questions?

1) What instrument do I buy to measure cable signal? and Modulator signal?

2) What should the signal measure on the instrument?

Thanks,

-Jym-
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post #2 of 3 Old 07-21-2001, 06:21 PM
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1) Verify Cable signal alone is good

Take a TV to the point where the CATV signal hits your house. Thats as good as it will get.

2) Verify Modulator signal alone is good.

By unhooking the CATV feed and without using an CATV amp ofter let the modulator feed the 13 TVs. This is where I start. Add an amp if needed working without the CATV signal.


3) Combine cable signal and modulator and make sure it is
good.

You will need to adjust the CATV amp and/or CATV level and/or the modulator level 90% of the time.


4) Distribute the signal through the house.

Hookup the splitters and check TV signal thru this process.

I need instruments and what I am looking for to complete this.

All TVs have different tuners. So don't judge the signal on just one TV. Newer sets are better for this project.

Questions?

1) What instrument do I buy to measure cable signal? and Modulator signal?

CATV meter! Cost $1000

2) What should the signal measure on the instrument?

At the TVs no more than 17db per channel and no less than 8 db per channel.


I created a distribution system on a house boat that has over 30 CATV outlets with 19 modulated channels from many different sources from many different locations with CATV. May take awhile but it can be done. This project was with all channel plus equipment.

Dave


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[This message has been edited by David Richardson (edited 07-21-2001).]

[This message has been edited by David Richardson (edited 07-21-2001).]
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post #3 of 3 Old 07-22-2001, 06:58 AM
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The tool I believe you are looking for is a feild strength meter. It measures the strength of an Rf signal in dBm. You will also need a set of in-line Rf attenuators and an Rf amplifier or two. The last piece of info you need is the length of the individual cable drops to the 13 tvs in 50' increments (long runs have an affect on signal strength). The signal strength you are shooting for is 8-10 dBmv at each tv location. The signal strength of your cable feed and the output of your modulator should also be equal before you combine the two. You should avoid more than two stages of Rf amplification in trying to accomplish those feats. Stark Electronics sells Blonder Tongue FSM's at reasonable prices. http://www.starkelectronic.com/btdfsm.htm
Channel Plus describes a method of making rough measure of field strength with <$10 in parts. http://www.channelplus.com/tech.htm
Channel Vision offers some model Rf system diagrams and a troubleshooting list on their website, along with a list of the attenuation factors of typical splitters and coax runs. http://www.channelvision.com/

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