Quest for (More) Fire

[radiobob]

Well, all the hard work and great advice have finally paid off: I'm at last able to get something or other on about 10 satellites. Judging from some reception difficulties more toward the middle of the arc, I've still got some more tweaking to do, but that's okay.

Here's the question du jour: recognizing that different transponders operate at different power levels, some signals are rock solid while others on the same satellite (or one only a couple of degrees away) are marginal or unusable...is this still just an alignment issue?

For example, Gospel Network on AMC6 (72W) is so strong it makes my teeth hurt. I've honestly never seen 75% signal and quality before. On the other hand, Ohio News on SBS6 (74W) is unwatchable with 71% signal and 2-5% quality (clearly we need more bits to get pix).

Likewise, on G10R (123W), the Pentagon pumps out 76% sig/35% qual and KFDF is 73% sig/23% qual, while KTWO is 76% sig/0% qual and nothing comes in on the 11720 cluster of stations. The Viewsat seems to need about 10-15% quality level before the dropouts become too bad.

So, how do I get more fire down the wire? More wrench-twisting tweaking ceremonies? More sheet metal?

Bob

[rainman]

you are getting very close bob sounds like you need to do some minor adjustment.

[wejones]

Originally Posted by radiobob

......

Here's the question du jour: recognizing that different transponders operate at different power levels, some signals are rock solid while others on the same satellite (or one only a couple of degrees away) are marginal or unusable...is this still just an alignment issue?

For example, Gospel Network on AMC6 (72W) is so strong it makes my teeth hurt. I've honestly never seen 75% signal and quality before. On the other hand, Ohio News on SBS6 (74W) is unwatchable with 71% signal and 2-5% quality (clearly we need more bits to get pix).

Likewise, on G10R (123W), the Pentagon pumps out 76% sig/35% qual and KFDF is 73% sig/23% qual, while KTWO is 76% sig/0% qual and nothing comes in on the 11720 cluster of stations. The Viewsat seems to need about 10-15% quality level before the dropouts become too bad.
.....

Some of the channels you mention are channels that a lot of people have problems with. For example there was a whole thread over in the Satforums forum about the 11720 MUX you mentioned. And for some reason, I have always had problems with anything on SBS6, even before a tree blocked it. It is a VERY OLD satellite (1990), and tends to have weak signals on it. I used to get Ohio News OK though, before the trees grew up and blocked both SBS6 and AMC6. I just cut the AMC6 tree, and haven't looked to see if it helped SBS6 or not... I hope so.
Also, some receivers have problems with very narrow signals, like the KTWO, particularly if your lnb drifts much. My Fortec receivers are only rated down to 2000 on the SR, and that signal is 2222, so check the specs of your receiver to see if it can handle low SR values. Also, some lnbs drift a lot, and you might completely miss a narrow signal like that. One of my old LNBs typically drifted 2-3 MHz often related to temperature, and when trying to tune one of those narrow digital signals, sometimes I'd just have to keep trying and eventually the receiver would lock on, and the afc would then follow the drift. Most lnbs aren't that bad, but most drift close to 1 MHz, and that KTWO signal is only 2 MHz wide, so if your lnb drifts, you can see that it might be a problem.

But anyway, before doing anything drastic to your tuning, one thing you might try, if you happen to have a TIVO..... What I do, when I have marginal reception on some signal, and want to determine whether it is due to alignment or if it is just that the signal is weak, I tune to the signal and put up the signals strength meter, and have it recording on my TIVO, then go outside and make very slow movements to the dish, pushing up, down, right, left, in all directions, being careful to hold it in each orientation long enough for the receiver's meter to respond. Then I go inside, and watch to see what the effect was on the TIVO. If all I see is the signal getting worse (usually the case), then I figure that the signal is just weak (for me, usually because a tree has grown in the way), and there is nothing I can do about it. BUt if I see improvement, then I know that I've lost my alignment (in my case usually because of spring freeze/thaw cycles), and need to tweak something. So before you resort to tweaking alignment, check to see if you can get improvement by push/pull.

[radiobob]

Thanks, Bill!

As always, you're right on target.

I don't know if it'll make a difference or not, but I already ordered an Invacom LNB from Satoun. We'll see how it plays. And, eventually I may go for a bigger dish.

The Viewsat specs say the VS2000 covers symbol rates between 1 and 45 MS/s, so I should be "good for go".

I popped over to Satforums and read the posts re: G10R and 11720; ran into a few other discussions about other "problem" channels I have. It's good to learn about others' experiences.

Thanks a heap. I really couldn't have done this without you.

Bob

[radiobob]

Originally Posted by rainman

you are getting very close bob sounds like you need to do some minor adjustment.

Rainman, thanks for your continuing encouragement. Means a lot!

Bob

[elgemcdlf]

Well Bob you finally got close enough to believe it is possible It really is just a matter of fine tuning now for you. At this point I am sure you have figured out how "fine" that really is and how "slow" slow really is You should be able to get everything listed out there with a properly tuned dish.

[radiobob]

Fine tuning and luck!

It's taken a fair amount of piddling with the interaction between the elevation and declination... and, there's clearly more to be done!

But, yeah, I guess I'm almost a "true believer". If I could only get the channels I want to come in like the doggone Gospel Network.

Bob

[wejones]

Bob
Since you are a HAM, it seems possible (likely) that you have a communications receiver capable of receiving 950 and 1450 MHz. If so, you might try experimenting looking for the beacons for these satellites. I've been trying to think of a portable alternative to using those little signal strength meters, so a couple days ago, I started searching for some of the beacons for these sats. I've tried this before, and didn't find them, but I had forgotten that the LNBs drift so much that I wasn't looking in a wide enough spectrum.
When I tried this time, I found what I'm pretty sure are the beacons of a couple sats, and they give me a nice signal strength reading on my communications receiver, and this wouldn't be confused by TI or signal coming in from nearby DBS satellites. The only problem is that these beacons are at different freqs, and they will show up at different places because of LNB drift. Ie most of these are within about half a MHz below 1450, and or half a MHz above 950, if you put a "T" with a DC-block in line with your LNB coax. I see them as just a quieting carrier that seems fairly narrow. I think I was picking it up on a 15 KHz bandwith mode, plus another bandwidth, not sure if wider or narrower. However most LNBs drift up to about a MHz.
But what I was thinking, depending on what receivers you have, would be to put a communications receiver in scan mode, scanning maybe a 1 MHz band around 950 and/or 1450, and hopefully the receiver would stop when it found a beacon, and you'd get a signal strength reading that was only from a satellite? You can verify it's a sat signal by switching polarity, and the signal goes away.
I'm not sure how practical this would be, I used a big desktop receiver that wouldn't be much good out at the dish, but if you have a small portable receiver, it might be something fun to play with.
Just a thought.