skew on AMC1

[turbosat]

I'm trying to figure out what the real 'skew' figure is for AMC1 for my location. I know this satellite has a strange setting compared to the others, but the dish pointer sites all seem to show it as normal. I get skew of 20 +- for 101, 22.9 for 103W, etc but my motorized dish scans the same tps twice on 103. Once as vertical and again as horizontal.
I know I can figure this out if I point a fixed dish at 103, which I plan to do, but was just curious what the real skew figure would be. Remember reading somewhere once that this satellite's skew was off by a large amount, like 20pts or so but I never wrote it down anyplace when I had a fixed dish on it before.

 

[Lak7]

I believe Dishpointer just uses math, based on the location you enter, to figure the skew. It doesn't actually know that Sat's Ku skew is messed up.

If I remember, 101's Ku skew is about 20-25 back to the East.
So, for you, if 103 is 22.9, I would Start at Zero of 101.

 

[Jim S.]

I think it's like 23 or 26 degrees from normal, clockwise facing the front of the dish.

The angle calculator at TheList is modified to give the proper value for this bird, unless it's been regressed to an earlier version for some reason.

 

[meinename]

I remember Iceburg usually saying -24 degree skew off from what the calculations say.
I always remember since he would refer to it like skewing for ONN.

When I had the Direcway pointed there, I could not get consistent results while trying to peak skew for the feeds.

Some didn't care like Pentagon channel and the NBC colorbar channels
The others like WCPE and feeds wanted a -14 skew or a -24 skew. Placing it in between at -20 got me neither.

We'll see what I get later when the SG2100 goes up. Maybe it's me.

 

[turbosat]

Thanks guys, I thought it was not just a few degrees different, but largely different from adjacent birds. If I can get a hole dug for a test pole I'll stick my spare 84e on that satellite and see if I get anything I might be missing now. Back when Safeway had its feeds on there, it was the only way I could pick that tp up, motorized dish couldn't see half the channels, but does find most of the strongest.

edit: TheList' calculator shows it about the same skew for AMC16 for me, haha. So all I need to do is aim at the color bars on 85, then turn dish and drop elevation. Great having that calculator-never noticed it was there!

 

[John Popper]

That's one of the sats I havent been able to get anything from with my setup (3m Dish, Coolsat 6000, positioner is old Echostar analog receiver.
How do you change the skew using the Coolsat?

 

[Lak7]

How do you change the skew using the Coolsat?

You can't. You need to actually twist the LNB in the Holder.

 

[John Popper]

I see

 

[Mr Tony]

I remember Iceburg usually saying -24 degree skew off from what the calculations say.
I always remember since he would refer to it like skewing for ONN.

very good. Someone has been observant

Its actually 26 degrees per the SES website
SES WORLD SKIES - Satellite Data

Polarization Offset 26.0° CCW (viewed from the earth)

This does not affect the C-Band side. That is normal skew

 

[WTguy]

Thanks for the link, supposedly just a couple more years of this bird's life. I cannot wait for that satellite to be replaced.
I have never forgotten my first attempt to get a feed of this satellite,,,it was the 02-03 basketball season which back then meant analog and also meant a poor signal resulted in a lot of sparklies. I messed with it for what seemed like a half before I got the game I wanted to watch with a screen full of sparklies. Finally during a media break in the second half I realized I was so far off theskew in the opposite direction, that I was watching a vertical feed with a horizontal setting. Corrected the skew and set the proper setting,,,,watched the last few minutes of the game with a great picture.

 

[delta_charlie]

Hi all, over the weekend I decided to re-task the fixed 80cm dish that I had on 97w and moved it over to AMC1 then I peaked the skew and found about 40 points on the signal Q over what the 80cm dish with the motor would get. Just wanted to post that in case anyone was wondering if it makes a big difference. I would have to say 40 points is a big difference ;-) Later, DC

 

[turbosat]

Thanks Delta Charlie that is a great amount of difference. I've been re-looking at my motorized dish, and it seems that it is getting both H and V signals, but it also rescans some of the V signals a second time and calls them Horizontal. Having a 2nd dish pointed at AMC1, or using a bud with a polarotor is the only means I can see to overcome the skew-offset.

 

[Mr Tony]

Some of the stronger TP"s on 103 dont matter much (Pentagon, WCPE) but to get the feeds you most definitelly need the skew properly done

A while back we had an uplinker post here about the abnormalities of AMC1
http://www.satelliteguys.us/fta-shack/108401-new-member-uplinker.html

also the news feeds on there they run at lower power than other channels.
http://www.satelliteguys.us/1047778-post12.html

Power levels are kept VERY conservative since it's designed for big dish reception. We only run about 1/4 of the transponder's actual power capacity to save the batteries on the satellite, and to minimize interference.

 

[turbosat]

Thks Ice, I remember reading those posts now. Is funny though-seems to me the way to overcome interference would be to saturate the transponder. Maybe I need to watch that PIT training again on 97, hehe!

 

[tester239]

Sorry to bring up an old subject, but exactly how long has this skew been an issue? I didn't have problems with AMC1 and NBC feeds until sometime in 2009 when I moved. I always figured I set up the dish wrong at my new location.. but everything else in the arc worked just fine.. including AMC1 C-band. I've been hurting for my NBC feeds (going to set up a 72w fixed dish at some point)... When I first heard about a skew issue, I tried manually setting the skew on my KTI 10'/CorotorII and still couldn't lock a single feed. I'm also under the impression that 12117MHz/4232H-5/6 is almost always active with the NBC blue slate. Is this still true? I have moved (yet again) and when I get the big dish back up and aligned, I'm going to try again...

 

[Jim S.]

I thought the skew problem was forever.

When you say feeds, do you really mean occasional news feeds or do you mean the permanent HD network feeds? The reason I ask is because the latter are DVB-S2 now, and I don't know what receiver you're using. (The good news is, they're no longer 4:2:2.)

Last time I was on AMC1, there was one or two SD, DVB-S channels that almost always had an NBC slate, but I have no idea what transponders they were.

 

[tester239]

I have DVB-S2 tuners, but I'm talking about the occasional SD DVB-S news feeds. The ones listed on Lyngsat used to be accurate? Are they still and I just need to play more with the skew?

 

[Jim S.]

I never saw a lot of feeds, usually just the same slates or fixed cameras over and over. But I think there's a tree branch in front of the satellite. (I'm going to verify that at solar conjunction this afternoon, as a matter of fact.) So I moved my dish elsewhere. It's not motorized, so I can't check right now. Sorry I couldn't have been of more help.

 

[tester239]

After getting some sleep and reading back (hadn't noticed a _second_ page to the thread while searching) I see that this has been a problem since launch. However, this does not seem to explain why only within the past year or so I haven't been able to get AMC1 NBC news feeds. If it really were a problem from launch, I would figure that a professionally installed 1m channelmaster dish installed in '99 on top of a 6 story building with a clear view of the sky for the AP NewsWire would be set up to compensate for the skew when installed.. unless.. oh. wait. Everything I'm picking up is vertical... sigh. Shows I'm paying attention! I suppose it's time to go to the roof....

This still does not explain my failed home sky-searching adventures though.

 

[Mr Tony]

AMC1 KU skew has always been off by 20 some odd degrees

This was even confirmed a few years ago by an uplinker when I asked about the skew

It was a launch/positioning anomaly. When it achieved permanent orbit, it was tilted by -- whatever it is -- 20 or so degrees.

There are now hundreds of uplinks that are permanently skewed "off" to compensate for it, so it'll NEVER change. So I have to manually rotate and manually cross-pole each time I go up.

http://www.satelliteguys.us/1047803-post17.html