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TV Respection Over a Hill

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thisthat

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TV Respection Over a Hill

I'm asking for your help and advice.
I will first explain what I want to do and why, and what I have come up with so far.
I live in Australia on a small Properity, My front gate is at the top of the hill where theres is good TV respection but as you go down the drive its gone and at 1.1 kilomtres to the house there is zero. Satellite TV is is to Expensive for what is in Australia, and free to air satellite TV does not cover the normal free to air stations.
What I have come up with so far is setup a TV antenna at the front gate with a tuner out of a old remote TV or Video to a 2.4 ghz stereo audio/video TX and antenna and 2.4ghz RX and antenna at the house coonected to the TV and another setup the same for the video for recording.

Can you think of another way of doing this that doesn't cost to much.
and no I won't move to the front gate :lol:

thisthat
 

flatulent

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use telescope

You seem to have the lowest cost solution, although you could have a video modulator which in the US is on tv ch. 3 or 4 and point the output to your house on a directive antenna. This restricts you to one ch unless you like to take 2.2 km walks frequently. The other alternatives I can think of are all more expensive. (1) Put your TV at the gate and watch through a telescope. (2) Use cable over the 1.1 km to bring the base band video to your house. (3) Make a repeater. At the gate aim one antenna at the TV station. Connect it through a few 10's of meter of cable to an amplifier and another antenna aimed at your house. To keep down oscillations, the antennas need to be directive and spaced far apart.

If the angle betwen your gate and the TV station is different than the angle from your gate to your house, try making a flat sheet reflector (it works like a mirror) out of chicken wire about a few meters square. Put it at your gate and orient it so the rays from the tv station are reflected towards you house.
 

sda

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Adding to Fratulent's previous post, and on the practical side of things..
If you decide to use the repeater solution, the setup could be as follows :
A high gain directional yagi antena for reception, located on top of the hill, a 35~ db masthead amp with at least a 110 dbm output to ensure that there is no overloading, feed that to a communal type of amplifier with a gain of 20~30 db and a 120 dbm (at least) output, this located as far possible down the hill (40~50m). The transmition aerial should be of a similar type but mouted for the opposite (vertical) transmition polorization.
Most communal type of amps have attenuators to adjust gain, so you can use them to ensure the setup does not go into oscillation.
All this offcoarse applies if all the chanels received are in one band (UHF), not being the the case AFAIK in Australia, unless things have changed sinse I was last down there (12 years ago).

The whole setup should not cost you over 350 $ for parts.

cheers
 

thisthat

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OK Repeater sounds good, but I don't think it would work over 1.1 kilometres, forgetting the cost of the cable from the front gate to the house, amplifing it very hundred metres would require 10 amplifiers and some means of power them.

I'm going to put some driveway lighting solar powered, but these power unit will be too far apart for powering amplifiers 300metres. Example(spu = solar power unit)
frontgatelight(pw)-------100metres-----light 100m light--------100m-------light(spu)--------100m------light 100m light-------100m-----light(spu)-------100m-----light 100m light-----100m----light(spu)------100m---light 100m house (switch on and off by tone control switch)

The antenna I will be using will be 91 element UHF 18db with a masthead ampilifier of 20db gain. The rest I'm still looking at for ideas that will work.

thisthat
 

sda

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I don't think you understood my previous post.
You signals are to be transmitted to your house, the reason for the vertical polorized second aerial 40 odd metres apart from your site of reception.
You'll need a vertically mounted aerial at your house for that reception.

sda
 

flatulent

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try natoural reflectors

Have you tried rotating your antenna at your house to determine if you can get reflections off the surrounding hills?

Do not reject the reflector idea without tryng it. This method is used in commercial and military systems. At UHF it does not need to be very large. For an experiment, try a 2 m strip of kitchen aluminum foil held by hand at your gate while someone else watches your TV set.
 

thisthat

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Sorry SDA I did miss understand you, I would like to try out what you are recomending for repeater solution, can you step me thru exactly what I require with this vertical transmition polorization antenna at each end. To see if I can buy them or use a horizontal UHF antenna set vertical modified ? back loob?
.
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flatulent Yes I have tried getting reflections of surrounding hills by rotating it, but completely dead. But have not tried a some sort reflection material.
Will give it ago.
thisthat
 

sda

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The aerial is of the same type as for reception, only difference is that instead of being mounted horizontaly as in most cases, it is mouted verticaly. The easiest way is to bolt a small pole ~50cm long verticaly, to your mast, then mount your aerial on that.

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cheers
 

Gakusei

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I have found that the rebroadcast scheme can work without an amplifier. As mentioned earlier, you need high gain yagis and you have to change polarisation to get good isolation between the two antennas. You need to have the two antennas about 2m apart and 10m from the ground and any other obstructions. There must be a clear line of site between the house, the rebroadcast antennas and the transmit antenna. This has worked in blind spots in the cotswold hills in England, but normaly in generaly high signal areas. If this doesn't work, then you will have to fit an amplifier which you could try powering from an old car battery and DC to DC converter. This should last a good few weeks between re-charges.

Good Luck
 

toonafishy

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I would also suggest using the passive approach first of one yagi pointed towards the transmitter and the other pointed towards your house, Low loss cable between them. This is pretty standard point to point microwave.

Sometimes, all you need is a dipole element that can see both the transmitter and receiver. The signal is picked up in the dipole and reradiated and picked up by the receiver.
 

S

sick_man

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my ideas from previous experiance of a hill in aus

you should use a small amplifier and run this from a solar cell charging a 9v or 12v battery

then use this inbetween your antannas

this way youll get 24- 28 db gain of the outgoing signal

you need

1} a 12v 50 - 500ma cell depending on the battery type and rate use a resistor to limit the current forinstance a 1.5v nicad normal tpye will require constant 50 ma charge for 8 hrs a day so work the cell type out on paper first

2} you need two good spiral yagi's this is the best for your 1.2 km to your house

and also another spiral yagi in free space on a small tower
as the "rx " one {so three in total inc your house}
3} two for the gate ..... amplifiers 20 - 28db gain over your freq range place these as close to the antennas as possible
4} one amp 24 db gain for the house



this way what you can do is build a small rotator and remote control it with IR to get the best "tuning" etc

also be able to adjust the gain of your signal


this is a cool system

good luck


h**p://www.antennafactor.com/adocs/m_new.php

a link to a company review of a software for this freq design

a tip is to make your own from nice solid copper type coax

change the ** to TT


h**p://www.armindia.com/antennadivision.htm

here is a good quality manufacturer
 

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