True South - Is this correct?

[mickstery]

Hey everyone ,

Just trying to figure out my true south correctly and thought I would run it past some of the experts on here :king-041:

So basicly this is what I understand:

I have found out my lattitude and longitude via multimaps:

this is :

Grid ref: NW442327
Lat: 54:37:30N (54.62487)
Lon: 5:57:47W (-5.96304)

So based on my longitude , I then use this as a reference to the satellite in the sky which is my true south satellite.

My true south satellite based on my longitude is AtlanticBird3 (5.0W)

From this point I need to calculate the magnetic Declination/Deviation.

I done this with a handy online tool here : http://www.ngdc.noaa.gov/geomagmodels/struts/calcDeclination

Based on a lattitude: 54 degrees north and a longitude: 5 degress west my magnetic Declination/Deviation is = +3° 57' W changing by 0° 10' E/year . So therefore I would add 3° 57' from the position of my true south satellite to actually get my true south?

In othe words my true south satellite is 180 degrees on the Azimuth and taking into cosiderationg the declination of 3° 57' = 183.57 degrees = my true south ?


I hope that is correct, can one of you guys on here tell me if I am in anyway correct or should I go back to the drawing board?

cheers :respect-062:

[dcselec]

Try using Google dish pointer think you put
lat/long in then it uses google maps it will point
a line to any sat from your location

[mickstery]

HA!

well thats useful.

it came up with

Latitude: 54.6237°
Longitude: -5.9610° Name: True South / True North
Distance: 38823km Motor Latitude: 54.6°
Declination Angle: 7.7°
Dish Elevation: --°
Elevation: 27.7°
Azimuth (true): 180.0°
Azimuth (magn.): 184.6°

However is what I previously worked out correct? my true south is 3-4 degrees + of my ture south sat on 5west?

[Bbigfoot]

Hi mickstery,

Conntect your motor to the dish, set Latitude to 55n.
Turn On S.T.Box, tune to BBc World (Thor 0.8w).
Your motor will be set to Zero (look on the back of motor for scale). your S.T.Box
will read (No SIgnal) just move dish till you recieve a signal
from BBc World. bolt up, thats It.

BF...

[mickstery]

cheers mate ill give it a go.:cheers2:

[gbmitie]

use dishpointer, you can even put in the motor you are using. I would use 5west for best reference, then arc will be correct = 100%.

let us know how you get on. will look for sat on 5west for you

gb--:hurray::hurray::hurray::hurray:

use MT Blanc, 11096V, 29950. 1/2 good signal

[mickstery]

if i have the motor aligned south and then align the dish exactly inline with the motor , everything should be fine ?

Or

is it a case of having the motor set to south then moving the dish to align with my nearest sat = 5w or 1w?
then tighten everything up?

[gbmitie]

The first one, motor on 0, dish pointing at 5west = true south for you, dont touch dish elevation but you can tweak motor elevation initially. then to get best signal you may have to fine tune dish elevation and motor, its trial and error.

i was watching sport all day

gb--

[Tmull]

At midday,1pm GMT in the UK the sun is due south on the Grenigh merridian. 0Long.00.00. For every 15 dreeges add one hour. Therefore for 5dreeges W add twenty minutes to miday and the sun is due south of you. Accurate enough for dish purposes but slightly incorrect for navigation as an equation called Equation of Time would come into play for navagation purposes. TMULL

[TonyO]

gbmitie,

are you saying that true south is at magnetic 5w, that seems about right to me, if I want 39e I usually take the magnetic reading which is about 34e and its never far out.

If you pop the question into google about true south and magnetic south you get loads of the most long drawn out complicated answers that go for pages of facts and figures in which the straight answer is never given !

[gbmitie]

I use the sat nearest to ones location and then use that as the starting point so the arc will be correct. I am -8.9w so use 8 WEST, in Wales I use 1west. And for the above I would use 5west. If there was no sat close by then that would be.... interesting.

gbmitie

[TonyO]

It seems from the site I just visted that the variation for london is 3' 1/2 degrees and not 5'

---------------------------------
(taken from an article on a board)

The relationship
magnetic grid variation = magnetic declination − convergence

still holds, though, provided the signs are handled correctly. For example, in the part of North London where I live, the magnetic declination is −2°25' and the convergence is +1°25': the magnetic grid variation here is therefore

(−2°25') − (+1°25') = −(2°25' + 1°25') = −3°50',

i.e. magnetic north is 3°50' west of grid north. On the other hand, at Penzance in the extreme south-west of Cornwall, the magnetic declination is −4°13' and the convergence is −2°43'; so the magnetic grid variation there is

(−4°13') − (−2°43') = −(4°13' − 2°43') = −1°30',

so that magnetic north is 1°30' west of grid north.

[Tmull]

Lads, As a retired navigator I believe you are getting bogged down on the Variation issue. True South is what is needed. The Sats on the ark have names and a No.expressed in degrees. Like Hotbird 13 degrees E. What that means is that Hotbird is at Longitude 13E directly overhead if you were at that Longitude and on the Equator or Lat 00.00. You cannot accuratly find a Sat with a compass unless you use a copmplicated maths formuls ,using Trigonotmery and know your own Lat,& Long. The simple method usually is the best.TMULL

[mickstery]

I would like to thank everyone in this thread for helping me out and explaing how to go about what I set out to do.

This evening I aligned the dish and motor to my south (using 5 west). I then tweaked the elevation on the dish making sure I was getting the best possible signal with the aid of a cheap satellite meter from ******.

All satellite are coming in loud and clear. Now I know how to do this in the future and am well pleased.


Cheers guys.

:respect-055:

[gbmitie]

well done and top man for posting back. Whatever you do dont mess with motor settings.

What I did as well was write down the signal strength/quality for each sat so that if it weakens you can figure out if it is on all sats, just one sat etc.

Enjoy


gbtipp

[mickstery]

gbmite,

I have another question for you if you dont mind :D

As I have said all sats are coming in nicely with a good strong signal.

However on 5east some of the transponders are fluctuating on there readings. For example snr 83% and agc 71%, jump up and down quite a bit and is not stable.

I am however pulling in the viasat xl cahnnels and viasat extra channels and some other french channels, France 3 & 5 etc.

Im thinking that all I have to do is go out and adjust the dish slightly to get everything stable on this satellite. But also thinking if I move it I will disturb everything else on the other sats.

what do you do in this situation?

[Bbigfoot]

Hi mickstery,

Pleased your Sorted.
If your using USALS you can tweek your Longitude (Save going up ladder).
When I posted I did not noticed your Longitude.

How to Tweek in USALS. If you have loaded your Longitude as (6w),
tweek it to (6.2w), then (Save).
Come out of (Motor Menu) check you Signal Quality, see if you have
a higher Signal. Just keep tweeking your Longitude for best Sig.
Each time you tweek your Longitude your motor move's 2or3mm East
or west depending on the Longitude change.

Its the Sig Quality that counts as far as (Black Screens) matters.
On a Humax STBox loss of Signal comes at (17%) below that and its (Black Screens).

BF...

[gbmitie]

above could sort you but quote the channels causing bother and we can have a look as well. Also was weather bad/windy when you were viewing, and large trees nearby with BIG green leaves, any rooftops? etc, quote the channels.

gb--