SatSig topic:

ASI (Adjacent Satellite Interference)

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Oct 13^th, 2010 at 6:42am

Am Having issues with (Adjacent Satellite Interference) ASI on 902,antennae size being 2.4 & a 10 watt BUC. though it has a long cable 120-150 mtrs it has been working well for the last 2 years, i have changed Connectors, cleaned-up the Feed-horn made sure Focus is ok, tried realigning But ASI wont clear. Anything Else i should do?

Oct 13^th, 2010 at 6:50am

Just to add into this am in Jarkata....and its an SCPC link, hope this is of help.

Cheers,
Muchugu.

Oct 13^th, 2010 at 8:55am

Verify that the problem is in the receive direction at your antenna.

Observe the interferers and your wanted signal and then move off the wanted satellite towards the adjacent satellite. If the wanted signal decreases and the interferers all increase as you approach the other satellite then you do have a problem with the receive pattern/beamwidth of your antenna. When you peak up on your wanted satellite the interferer should NOT peak up simultaneously in the same fashion. Can you see multiple interfering carriers that all match the carrier pattern from the adjacent satellite ?

Ask for help from the satellite operator if you suspect that there is uplink interference into your wanted satellite, such as from one carrier from one uplink dish working to the adjacent satellite.

Regarding your dish. If the dish is distorted, for example by the sides being pulled forwards by the weight of the feed/BUC/LNB assembly, then the gain may be several dB low and the beamwidth much wider than it should be. Do the two fishing line test. Put tight strings up/down and sideways across the front. They should just touch (<1 mm for Ku band) in the middle where they cross. If not, pull back the sides till the front rim is exactly flat. Re-peak the antenna pointing and see if the adjacent satellite interference has gone.

Best regards, Eric.