LNB moving or satellite moving?

[Jim S.]

Here's a weird situation. Last week I added extra LNBs to my 30" dish at 97. I set up one on 91 and one on 103 for feeds. (Would've liked to go to 105 but I didn't know if the dish would support it and it might be behind a tree. I'm not even sure if 103 will be clear in the spring.) After looking at feeds for a while the one on 91 is obviously not at the best point and I'll be tinkering with it tomorrow. But the one on 103 seems to be getting good signals on everything so far. Here's the weird part: at night (I'm not sure when it starts, but it's up and going strong by 2AM), I get RTPI, apparently from 101! My Coolsat reads it as 12031H, SR 2997, PIDs 33,34,8190. I don't get any other signals at all from 101. But this one transponder is coming in at a signal level of 82%, and the quality is at 58%. This is on a box with a threshold of lower than 30%Q for four-digit SRs!

At this point I'm not inclined to mess with the LNB, because 105 seems to be OK so far and I've actually seen a program I like on RTPI. But I'm curious, is something in my setup flexing in the cold (it's below freezing, and the signal is always gone the next day), or is the satellite drifting around that much in orbit?

(Besides RTPI, tonight I also discovered an unlisted audio channel. But I have no idea which satellite it's on, because its transponder doesn't even appear on Lyngsat for either of them. I guess I'll have to see if it's there in the morning. I don't know if it's permanent though, because it has a generic name and EPG data of "Test".)

 

[pedrogarcia]

Station-keeping on sats is an interesting subject. North-South drift is affected by the gravitational pulls of Sun and the Moon's orbit around the Earth. The East- West drift is affected by Solar radiation pressure. Left unadjusted a sat can move up to 1 degree either way but this clearly does not happen, ground telemetry keeps the system in check.

Having said all that budget plays a huge part. Operators want the birds and their fuel to last as long as possible especially now they have to have a reserve to take the bird to its graveyard orbit to decay at the end if its useful life. Of course the trick here to sell the bird off to someone with some life left so they have the problem. All of which means drift parameter allowances are a little larger than ideal, but hopefully not I think your problem.

Drift is more noticeable on the fringe of the footprint. Your bleed of the reasonable strong transponder RTPI is more likely to be the 103 LNB alignment or even slight dish imperfection or possibly both