Install Progress and question

[TimeHorse]

Well, it's been a week since my 75 cm arrived and still no service. After all the difficulty of putting it together finding a proper mount is not as easy as it might seem or was for many of you.

As I live in an arboreal area, there are lots of natural and artificial (neighbouring houses) obstructions to a good line of site.

After I spoke with the DirecTV technician who was here on Thursday, he said I might try the mounting below the current dish which is bolted to the foundation of the house. Unfortunately, that was for a mini-dish and was not the right radius for the 75cm StarChoice dish.

So I decided to take advantage of the aluminium rod towards the rear of the house on the same West-South-Western wall. I followed the advice from Kusat and got some U-Clamps that fit snugly along the pipe. Then went to Lowe's (much better than Home Depot around here for stuff!) because the bolts on the baseplate are 5" apart and the U-Clamp is a 2 1/4" clamp. After chatting with a very helpful fellow at Lowe's named Rob, we decided that an L-Shaped support could be used to compensate for the different lengths. So I spend all day cutting with a hacksaw the L-beam into 6" pieces, filing the holes so that there were 2 at 2 1/4" apart and filing down the edges, spray-painting the pieces and then hooking them up to the Satellite base plate. A number of ratchets later and I had a very snug fit on my aluminium pole. After adjusting the mounting of the dish, I put the dish on my new mount and got my wife to read me the numbers from the DSR 530 diagnostic screen.

I got 2 numbers to work from to align my dish. The first is from Kusat's tool. I plugged in 111.1 for Anik F2 and 107.3 for Anik F1 and got:

Az-True  Elevation  Skew  Az-Mag
224.57   34.13      61.9  235.05

I also looked up Alexandria, VA on Mike Kohl's lookup table as that was the closest point on his list to my house at 17 arc minutes 23 arc seconds from my location. This gave:

Az-True  Elevation  Skew  Az-Mag
227.1    32.9       125   237.58

BTW, does anyone know how I make this calculation so I can verify the results myself. I know my Longitude and Latitude to several decimal places so I should think I could arrive at a rather accurate result.

Now, there are a lot of magnetic fields around my house so getting a good compass reading is tricky but I more or less got it aligned by sighting a point along the line my dish should be pointing. I tried both elevations and twiddling the Azimuth within the 2 1/2 degree range and all kinds of skew but with no results. Also, although it's easy to set a skew of 61.9 on the 75 cm elliptical, I'm not sure how you could set 125 as the dish won't spin that far. The strange thing about the 75 cm dish is that the rest (no skew) angle reads 90 degrees and one can only skew the dish lower as far as I can tell. In other words, I can't twist it the other way so the mark on the left side of the dish reads 125 degrees.

Is there something I'm missing with the skew reading?

Anyway, I also tried aligning the dish with the DirecTV receiver to no effect. After an hour of all 0's on the signal meter my wife and I gave up. It's possible that our neighbours house is in fact obstructing our line of site. I have no way of surveying how tall his house is and thus how far I must be to overcome it.

So it looks like I will end up hiring the professional installer to help me with it on Tuesday. Hopefully, he can use a signal meter to make sure I get a signal from Anik F1 and F2 so I don't have to try F1, activate, and then try F2 and adjust my dish again because putting it on the roof will make it inaccessible. Also, I hope he finds good studs on which to mount the dish.

So it looks like I'll be taking off this Tuesday and hopefully can have Z-Télé by the following Tuesday and BBC Kids as soon as Wednesday. Yeah!

Fingers crossed!

 

[Firefighter Dan]

Try adding 8 degrees to your elevation. I had to do that on my 75E. Then work your mag reading from there slowwwwwwly.

I pointed at the 111.1.

Feel free to PM me about this.... I'm enjoying my *C

 

[TimeHorse]

Thanks. So I upped the Elevation to 41 degrees as you suggested upping it by 8 and that assumes 32.9 for Alexandria + 8. I twisted around 237.58 Magnetic Azimuth but still no signal. I kept the Skew at 61.9 since I still can't figure out how to set it to 125 though 55 degrees would be doable if the Mike Kohl numbers are reversed.

The pro wants $200 to do it so I'll try again tomorrow and if I can't get it working by tomorrow night, I'll have the installer come tomorrow.

Thanks again for the advice.

 

[wherron]

Hey TimeHorse - the skew can be set from 0 to 180 and the degrees are listed on the plate. The default is 90, straight up and down. Turn the dish to the left (facing it from behind) for values >90 and to the right for values <90. Many of the programs I came across gave me a skew value like 31.5, but this is for Europe. For Western longitude you want to add that number to 90 to get the correct skew. Be sure to line up the value with the indicator to the left of the plate.

I got my 75cm dish setup yesterday, with the help of a friend, and activated today. I'm getting 10.5 EBNO on most channels with an 88 signal strength. I think this is pretty good. Most of the channels look great,

I'm not an expert on any of this so maybe someone else here can offer some better advice, but I'm fairly certain you want a skew >90.

Good luck.

Thanks. So I upped the Elevation to 41 degrees as you suggested upping it by 8 and that assumes 32.9 for Alexandria + 8. I twisted around 237.58 Magnetic Azimuth but still no signal. I kept the Skew at 61.9 since I still can't figure out how to set it to 125 though 55 degrees would be doable if the Mike Kohl numbers are reversed.

The pro wants $200 to do it so I'll try again tomorrow and if I can't get it working by tomorrow night, I'll have the installer come tomorrow.

Thanks again for the advice.

 

[TimeHorse]

Skew

Congratulations, wherron!

Actually, if I go by the Mike Kohl numbers, east coast will have 90+ positive Skew but the west coast of North America will have 90+ negative Skew (somewhere around longitude 107.3 and 111.1 .

The Kusat site is based in Montréal but the tool might be from Europe which is so far a-skew from 111.1 and 107.3 that they may just be getting results that make no sense if they are not assuming "Western Longitude", though the Kusat tool does explicityly say west. I suppose on European lookups I'd use negative longitudes for the Satellite locations. That may get the right result. Technically I think Mike Kohl numbers look to be known good but I really wish I knew how to calculate it myself to make sure.

Anyway, I'll try the anti-rotation again -- hopefully it won't stick. Thanks again!

 

[miguelaqui]

Timehorse....I live near you, well, sort of! I have my 75E dish Elevation 36 Skew, yes! 125! Take the dish off the mast. Loosen the bolts holding the skew plate, the ones with those brass-looking tabs under them. Spin the skew plate to 125...you will see a grove in the dish which will indicate where the skew is.

As far as people saying point to 111.1.....You wil not be able to read 111.1 on the receiver until after the receiver has been actived, yes a big pain!!

Put the receiver on either 299 or 200, go to the signal strength meter and turn in *C. If you get a good signal on 200 or 299..my 200 is 79 and my 299 is 82, with the skew set properly, after you have the receiver activated, go to 298, yes, it's in French, but you will be able to tune 111.1 better, if need.

 

[wherron]

That would make sense - your skew angle is dependent upon your longitude relative to the satellite's position and not what side of GMT you are on (it was late and I was tired when I wrote that ). Using a program like Satellite Finder gave me numbers like 31.5. At first I had my skew set to this, but this tilted the dish in the wrong direction. I then realized the program's 31.5 was with 0 as the starting point. I added 90 to it to come up with my correct skew for the 75e. Actually, I took all of the numbers for 107.5 and 111.1 and split the difference to determine my skew, az and el. I'm pretty sure you will want a skew ~124.

Good luck.

Congratulations, wherron!

Actually, if I go by the Mike Kohl numbers, east coast will have 90+ positive Skew but the west coast of North America will have 90+ negative Skew (somewhere around longitude 107.3 and 111.1 .

 

[HDTVFanAtic]

BTW, does anyone know how I make this calculation so I can verify the results myself. I know my Longitude and Latitude to several decimal places so I should think I could arrive at a rather accurate result.

Well, you can either post your lattitude and longitude or use Mr. Lutus' formula:


final double toDeg = 180.0/Math.PI;
final double toRad = Math.PI/180.0;

/*
*
* ComputePos(input: (earth) lat (deg), lng (deg),
* (satellite) satlng (deg),
*
* output: Complex = az true (deg), y = el (deg))
*
* az format: North = 0, East = 90, South = 180, West = 270
* el format: Horizontal 0, Vertical 90
*
*/

private Complex computePos(double lat, double lng, double satLng) {
double dlngr = (lng-satLng) * toRad;

double az = Math.atan2(Math.sin(lat * toRad),Math.tan(dlngr)) * toDeg;
az = (270.0 - az) / 360.0;
az = az - Math.floor(az);
az *= 360.0;

double r1=6.6107; // ratio synchronous orbit/earth radius
double clng = Math.cos(dlngr);
double clat = Math.cos(lat * toRad);
double v1=r1*clat*clng-1.0;
double v2=r1*Math.sqrt(1-clat*clat*clng*clng);
double el = Math.atan2(v1,v2) * toDeg;
return new Compleaz,el);
}

/*
*
* ComputeSkew(input: (earth) lat (deg), lng (deg),
* (satellite) satlng (deg),
*
* output: double skew (deg)
*
*/

private double computeSkew(double lat, double lng, double satLng) {
double dlngr = (satLng-lng) * toRad;
return (Math.atan2(Math.tan(lat * toRad),Math.sin(dlngr)) * toDeg) - 90.0;
}

// The rather simple "Complex" class:

public class Complex {
private double x;
private double y;

public Compledouble x,double y) {
this.x = x;
this.y = y;
}

public double ) {
return x;
}

public double y() {
return y;
}

 

[TimeHorse]

Thanks guys!!

It's up and running now! It turns out the 125 Skew relative to 90 was correct and with the elevation at about 33 I got a hit while spinning the Azimuth and bingo saved myself $200 and only had to spend $40 in parts! We fine-tuned and get and 85 signal or 9.5 dB.

And BTW, with the A8 software now downloaded the DVI interface looks GREAT, even for SD programming.

I think Z Télé is one of my favourite channels too.