Dish pointing down?

[carled9]

Hi all... been reading with interest the motorised/moteck threads... guess what I've been doing all evening?

Well.. I was about to give up in disgust when I got something. Technomate 1500 & SG2100A. 80cm triax mesh dish, based in Leicester.

Was trying Thor 0.8W, no signal. Finally reset everything, sent satellite to 13E and got a tiny signal, moved dish elevation and azimuth on pole, not motor, to maximise signal and got maybe 65% on level and 75% quality.

Added 28.2E, dish moved, level at 75%, quality 85%. Tried Thor 1W again... nothing. 24% on both. Neighbours roof could just about have been interfering so tried 30W, which is well clear of roofline. Nothing on level or quality.

Strange thing is, by this time, the dish is sort of canted right over so the lnb is sitting at, say, about 4pm on a clock face and the dish is pointing pretty much straight at the ground about 50 metres from my house! (dish is about 8m from ground, just under gutter).

Now I can see it's an offset dish and that the nearer true west I get, the more it'll point at the horizon, but this seems to have more chance of picking up the neighbours labrador farting than Hispasat where it is...

Anyone any ideas what I'm doing wrong here?

Cheers,
Carl

 

[rolfw]

Hi Carl, you really are going to make life hard by jumping too early into the moving the dish with the receiver stage. You really need to set up on your due South point first.

If you reall believe that you cannot see 1 West, then drive the motor using the buttons on the body, to the 13 East marker on the body and then by moving the whole assembly on the pole and the elevation of the dish only, try and get a lock. To test that you are on the correct satellite, do a single transponder scan on one where you know the available channels. This should give you a base to work from.

 

[carled9]

Well, I didn't leap *straight* into moving it with the receiver! I just wanted the technomate to think it was on 13E before I moved the dish manually! Too dark now, so I'll have to check tomorrow. However, on doing a scan, 13E is definitely 13E - known channels are on there...

So what "sort" of perceived angle of elevation should the dish be at with, say, 30W? Certainly not pointing at the neighbour's hyacinths, I'll wager...

 

[RedAltoGL]

Where the dish points has no relationship as to where the signal is coming from. Most offset dishes have an offset of 20+ degrees. The signal comes from "up there" rebounds off of the dish face to the lnb. It is not coming from the neighbours plants.

Wait until you get round to 58-61 degrees west, set up looks really wierd, but just think about where the signals are being sent from, angles and elevations and then take into account the offset of the dish.

Redmund.

 

[carled9]

Yeah, I understand the offset thing and I've just been looking into this on various websites... trouble is that I haven't yet really found a single resource that gives a definitive answer that I can see.

I'm definitely concerned about the neighbour's house being in the way for maybe Thor at 1W but for Hispasat, it really shouldn't be an issue. If I stand directly by the dish and look down the LNB arm, it's pointing well to the right of the neighbour's house, so it can't be in the way.

How can I definitively work out the "line of sight" I need on the setup? Using www.satlex.net and my coordinates (52.58N, 1.19W) I can see that for Thor 0.8W I should be at 179.51 az and an elevation of 29.94. BUT... there is also the "declination" angle of -7.48, so, in effect, should the elevation angle therefore only be 22.46? Now this is the angle from the offset dishes point of view, right? There is an adjustment on the elevation on the dish mount that I have set to around that figure - it's a bit difficult to be precise with the size of the scale on there! Now at 22.56 degrees elevation with an offset dish, if I'm standing next to the dish (on a flat roof!) should the dish "appear" to be pointing downwards? When allegedly aimed at 30W, the LNB arm is pointing at a spot on the ground about 50 metres from my house... As the dish is mounted just under the eaves of a standard semi, this seems wrong, but maybe it's right? Who knows...

Really I need to know how to work out if the neighbour's house is getting in the way of the line of sight of the dish, but I don't know what line of sight I'm looking for, due to the offset of the dish!

If I get out a protractor and draw on a large piece of board an angled line at 22-ish degrees (or should it be 30 degrees for line of sight?) then put that on the flat roof under the dish, then, from the side, use a virtual parallel line from the dish to see if it clears the neighbour's roof, should that do it?

 

[Analoguesat]

When you are looking for Thor, make sure you arev looking for a transponder which is actually available to the Midlands - lots of them are on Nordic beams which are weak in the UK

 

[RedAltoGL]

This might help you:

http://www.geomancy.org/orthographic/html/section-3/3-1.html
Redmund.

PS Elevation of 1 west for your location is 23 degrees, Elevation of 30 west for your location is 18.5 degree. Hence with an offset of 20+ degrees the dish is pointing down when on Hispasat and upright when on Thor.
Active transponder for 1 west, BBC World 11325 H, 24500, 7/8.
Redmund.

 

[carled9]

Cheers - I'll give that a try later. Question still stands though - am I looking for 30 degrees or 22-ish degrees?

 

[rolfw]

I've attached a picture of my dish, similar longitude and a little lower down the country (difference of about 1 degree in elevation higher on most sats), it is pointing at 28.2 East, about the same elevation as 30W. Looks like your motor is sending the dish way too far.

When testing for line of sight, I normally swing the whole assembly around to the furthest points of the arc and have a scan for them, but it is a lot easier obviously when you have a meter.

If you go the protractor route, then you would be looking at a line from the bottom of your dish to the top of any nearby obstacle, I use the Swedixh microwave calculator to work out the relevant azimuth and elevation details. www.smw.se

 

[claasi]

Carl if you look up you will find a thread above yours were Ralf and myself had a discussion to help Clive on his issue.

http://www.satellites.co.uk/php-bin/forum/showthread.php?t=44722

Just read through the thread and try it out. Since you can not aim to Thor then use a compass and set the zero of the motor to the south and the dish as well of cause. Now turn your motor to 30 west and look up if the motor stops at the position on the scale what it says on satlex. If yes perfect then. Hope your latitude is correct on your motor ? If yes then you just have to take care of the dish. Now move the dish up and down till you hit the signal. Be aware you have a proper frequency on 30 west. You should get a signal now. If, then it fits for all other birds too.

Good luck!

Claasi

 

[carled9]

OK - I'll give that a try, thanks. How do I tell the Technomate to go to 0? If I manually move the dish to 0 and the technomate thinks it's at 13E, then when I tell it to go to Hispasat, it'll go too far, right? Do I tell it to go to 0.8W, and then move the dish to 0 manually?

 

[rolfw]

I'm not sure of the commands on the Technomate, there is normally a return to reference or send to "0" command in the motor control section. If not, turn off the DiseqC and perhaps reset the receiver.

 

[claasi]

Not sure what you mean. Why does the receiver think when you move it to 0 it is on 13E ? Turn of the receiver and usually all motors go to zero position. If not then move it manually be remote control or on the motor with the buttons. Then aim the whole motor with the dish to south. Now when you select Hispasat in the receiver menu, if it is stored, it should move automatically to that position if your receiver supports this. If not than move if manually with remote control again or the buttons to the position what it says on satlex.for 30 west.

Claasi

 

[carled9]

No, you're missing my point... It appears (in my highly limited experience!) that my Technomate retains the memory of which satellite it is on. Therefore if it is currently on 13E and I'm viewing that channel, there's no point in me moving the dish manually to 0 degrees, as when I move it by motor again, it'll be out by 13 degrees.

I therefore needed a way to tell the receiver to "go to zero" first and THEN move the dish manually back to 0.

Basically, I'm very close to 1 deg West where I live, therefore the "zero degree" position is going to be pretty much due south, correct? An azimuth of 180 degrees? If I start there, then tell the receiver to go to 30 deg west, then try manually moving the dish slightly until I pick up a known transponder on Hispasat, that should help me set things up, right?

 

[Analoguesat]

Yes - always set a motorised dish up at the due south position first - in your case 1W. Once its correctly set up, all the other satellites should slot into place naturally.

 

[claasi]

Carl I get you right :-) The first time you set up the motor what did you do ? It apperars that you receive 13 E currently. What does it show on the scale on the motor on that position ? Is it what it shows on satlex for that position on 13 E ? I don't think it does ! I assume your motor runs out of orbit.

To get the zero postion of the motor just shut of the receiver and take a look on the scale. If this is the case then turn the whole lot (Motor + dish) on the pole. Besides is your pole vertical 100% ? If not you will never have a proper setting up of your motor. Use a water scale to check your pole. This is very important otherwise your motor will never drive along the clark belt.

 

[carled9]

Success! It was the age old problem... I had it pretty much set up right, but the default transponders used by the Technomate had nothing tranmsmitting on them! As soon as I used the list shown in the "sticky" bit of this section I got channels straight away. So all along I was getting a signal from 1W and 30W but I didn't know it. I have had to readjust elevation and "base position" azimuth slightly, but I get a full range now.

I took a portable tv up on to the flat roof during realignment and tweaked the settings all ways until I got peak signals (up to 70% level/90% quality on some sats and only 50-ish% level and quality on others, such as Hispasat, is this usual?).

Whilst re-seating the pole and motor settings I manually held the dish assembly much higher - over the eaves of the house so it was well clear of the neighbour's roof and it made no difference at all to the signal strength, so I must be just ok where the dish is sited anyway.

Thanks for all the help guys - much appreciated.

 

[claasi]

I took a portable tv up on to the flat roof during realignment and tweaked the settings all ways until I got peak signals (up to 70% level/90% quality on some sats and only 50-ish% level and quality on others, such as Hispasat, is this usual?).
[/QUOTE]

Congrats !!!
Besides the best method with the porti TV since I did the same otherwise you get crazy.

Not sure about your Hispasat becuase it could perhaps be a bit more than 50%. Ok you have 80 cm dish but EIRP 51 in your area is actually strong and a 55 cm dish should do. What LNB do you have ?

Cheers
Claasi

 

[carled9]

I have the MTI blue line 0.3db one... was told it was good. As I say - on Hotbird and Astra it gives me around 90% so it seems to work fine.

 

[RedAltoGL]

Well done, I'ts a nice feeling when everything just falls into place. The readings that you are getting, seem ok. Over a number of years and useing different receivers I have found that there is no corrolation between one make and another. At present I get a rock steady picture on a Technomate that shows 20% quality on Nilesat whereas the manhattan shows 45% quality and is very blocky.

Anyhow, well done and welcome to the world of fta satellite TV.
Redmund.