Rotating satellite dish
This description applies to linear polarisation with names: Horizontal and Vertical.
Prior to attempting to point the dish at the satellite you need to pre-set the polarisation. The polarisation refers the axial rotation of the feed horn/LNB/BUC assembly at the front of the dish. There will be some kind of clamp around the feed throat which may be loosened sufficiently to allow the feed assembly to be rotated. There may be a tiny scale, possibly marked + and - either side of central. Ignore the + and - signs and concentrate just on the scale steps, try to determine how many degrees between each tick mark, perhaps 10 or 15 deg ? Quarter of a turn = 90 deg. In some cases the entire dish needs to be rotated to set the polarisation. There will be a large circular scale behind the dish.
Polarisation setting is a two step process:
1. Start by setting the polarisation to nominal. If you are trying to receive a polarisation called "Horizontal" then you need to set the feed so that the broad faces of the LNB input waveguide are on either side. If "Vertical " then set the LNB waveguide so that the broad faces are on top and underneath. Universal Ku band LNBs for satellite TV reception have internal switching between Horizontal and Vertical controlled by a voltage in the cable. These LNBs need to be initially set 'upright'.
2. Now, based on calculation, make the required polarisation adjustment. Face towards the satellite. A positive + rotation adjustment means turn the feed clockwise. A negative - adjustment requires an anti-clockwise adjustment. Ignore any +/- on the scale. it may be the wrong way round. Numbers like 0, +45, -45, -90, +90 may also be back to front. Think: + means clockwise when facing towards the sky in the direction the dish is pointing.
More useful links:
Finding the satellite:
The principle to follow is: Set the elevation angle (the up/down angle) really accurately and then swing the dish around sideways boldly, but slowly, till you find the satellite.
For the elevation angle: use Azimuth and elevation calculator or to calculate the required angle if you already know your latitude and longitude. If you need to find your lat/long go to Find your lat-long which uses on-line Google mapping. This page gives you dish pointing angles also. Set the dish elevation angle on the scale on the bracket behind the dish.
You need to know where your are located (latitude and longitude). I have two pages to help you do this. The first helps you find your latitude longitude in decimal degrees, the second which also shows satellite photos on a larger size gives latitude and longitude in degrees and minutes format as well.
To recognise that you are on the correct satellite you need to have some kind of detector.
Inexpensive power detectors will give an indication as you pass each satellite, but don't tell you which one you are looking at. This is adequate if you can recognise some significant satellite which will provide you with a known reference satellite. You can then count along the orbit till you come to your wanted satellite.
Satellite identifiers comprise a satellite carrier receiver (normally for digital DVB-S TV type carriers) pre-programmed to detect a particular carrier with a specific symbol rate and frequency. If the pre-programming of your identifier is correct and the expected carrier is present then you will see on a screen verification that you are on your chosen satellite. This is attractive if you are regularly installing dishes to work to TV broadcasting satellites. Beware that carriers with identical or very similar symbol rate and frequency may occur on nearby satellites. LNBs have frequency stabilities in the order of +/- 1 MHz so a satellite identifier may be unable to distinguish between two satellite carriers of the same symbol rate but with frequencies within 1 or 2 MHz of each other. You must have preset your polarisation correctly first. You must also have an LNB with the same local oscillator frequency as used when the satellite identifier was programmed and understand how the local oscillator frequency of the LNB may be changed, by 22kHz tone, by voltage or external dongle.
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