Rural Kentucky Antenna Setup

[tvreception]

I didn't use the amp gain figure. Please correct me if I am wrong, but this is what I was taught:

The NM present at location is 18.9

Then you add the gain of the antenna, this figure would be required, otherwise you are not factoring for the signal strength of the antenna. In this case the gain of the antenna being discussed is 14.5. If you add these two figures together you will get 33.4.

Next we subtract the amplifier noise figure, which is 2.9 in this case, which would leave us a total of 30.5.

The only other way that the amp figures come into play, is if the system losses after that point (on the way to the TV) would total more than the gain, which in this case would be 19db, which it won't.

Tvfool.com also discusses this analysis here http://tvfool.com/index.php?option=com_ ... view&id=57 and , unless I am reading it wrong, it says the same thing.

Please look this over, and let me know if I am not thinking correctly.

Tvfool says:
...Antenna gain is the only quantity that should ever be ADDed to the NM value. Most antennas will specify their gain in dBd or simply dB, and this is the value that should be used...

...pre-amps will actually cause you to lower your Noise Margin. No matter how much gain an amp or pre-amp claims, it will actually reduce your Noise Margin by the amount listed as the Noise Figure (NF) in its specs...


Steve
http://tvreception.net

[tigerbangs]

I was mistaken about your initial noise margin. You calculations are correct as you presented them: My bad! Sorry!

[simnaj]

Thank you tvreceptions and tigerbangs! I'm going to try and merge your suggestions and see what you think.

I am no longer looking at Bowling Green, good point tigerbangs, regarding broadcasters using two digital channels to transmit HD signals...40.1 and 13.1 are being broadcast in HD, while 40.2 and 13.2 are just DT.

So I decided to concentrate my efforts on Lexington...My concern here is that I would need a dual antenna assembly (to capture low VHF) and with a metal roof and the required mounting distance between the antennas themselves and the roof I do not think I could accomodate an adequate rig to support.

So I resort to Louisville...This is the direction I am leaning right now. Why? All major networks broadcasting in HD, realatively decent Noise Margin across the major networks, no need for low VHF (again I am only looking for ABC, CBS, FOX, NBC), may be able to accomodate a single UHF/VHF high antenna (tvreceptions suggestion Winegard HD7697P) and finally no need for rotator (I have a dual tuner and want to be able to record two channels simultaneously without regard for directionality).

Thoughts? Am I close or way off? Thanks again for all of your advice...I look forward to posting the results.

[tigerbangs]

I'm a little iffy about using Louisville all by itself for TV reception: we may be surprised and find out that everythng comes in well, and that would be great, but your signal strength and noise margin on those stations, and the distance to the stations makes me think that Louisville may not be reliable 100% of the time, and that you ought to have a rotator as a back-up so you can see Lexington and Bowling Green as a back-up. I still contend that separate antennas are the way to go here, espeially on UHF, but you pay your money and take your chances...

[simnaj]

A rotator is not an option...I have a dual tuner receiver (TiVo HD) and I want to be able to record two channels simultaneously. I also want to be able to setup automated recording (Season Pass) without having to think about making sure the rotator is in the right position at the right time on right day.

Two antenna's is an option, but again, I have a metal roof and only about ten feet above the roof line to the topmost antenna (UHF), leaving the VHF antenna just six feet above the metal roof?!?

[tvreception]

at this point about all you can do is buy the antenna system, and if it doesn't work out, aim it for your original location. You really don't have any other options.




Steve
http://tvreception.net

[tigerbangs]

It's true, but I suggest STILl including a rotator just in ase your origital plans have to change: it's a LOT easier to see what's happening wth the signal quality meter on your TV set or converter box than it is to screw around on your roof and try to adjust an antenna after the fact. Spring for the rotator!