Mounting A Satellite Dish Or Rotor

2  Dish & Rotor Alignment Settings Calculator (with internet mapping)

Updated February 2017.

For anywhere in the world this page calculates all the setting angles  azimuth, elevation, skew (aka polarisation tilt, polarisation angle), rotor tilt  needed to point (align) a satellite TV dish to a given satellite, and can display on an internet map the required azimuth (bearing or direction), or calculate the compass or grid bearing for use with a printed map.  To realise its full potential, first time users are advised to read the General Help.

Help

Page loading is staged  -  as soon as possible the calculator's form unlocks so that you can begin entering data, further options becoming enabled as the code to support them completes loading.  The options available also depend on the chosen receiver location as follows:

  • Anywhere  -  Google Map displays a direction line for aligning the dish, while the calculator shows the true azimuth (degrees clockwise from True North), and another azimuth corrected either against Grid Variance (Grid Convergence, Grid Angle) for use with a printed map, or against Magnetic Variance (Magnetic Declination) for use with a compass.  As accurately as possible, enter locations for the receiver and satellite, click the map button, and if required drag the markers to a more precise location.

    The map has two choices of base layer selectable by the buttons in the top right hand corner.  Satellite pictures can take significantly longer to load, so it's quickest to use Map to get as close as possible to the intended final location and zoom level before switching to Satellite.

    Satellite images are often subject to perspective distortion, often to an extent significant in the context of aligning a satellite dish, thus making their results potentially less reliable than the initial impression given by their simplicity.  Although it may seem counter-intuitive, you should work entirely from ground level  position the marker at the point on the ground beneath the proposed dish siting, and choose as aiming point a landmark the base of which is crossed by the line.

  • UK Mainland Nations & the IoM  -  UK OS Map displays the azimuth on an Ordnance Survey map.

    Coordinate conversion between Lat/Lon and E/N doesn't use OSTN02™, so coordinate readouts should only be considered accurate to around 5m.

    OS's OpenSpace® on-line mapping covers UK mainland down to street level (other UK nations are covered by other agencies and are either only available via OS at low-scale or not at all).  If, despite the coordinate vetting, you manage to create a map of somewhere not actually covered, the map may just show nothing, or stick on an area on the north east coast, in which case Ctrl-Click the map button to remove it, and just use the Google one. 

If you plan to print either map, please read the Notes.

If some of the terms or techniques mentioned here are unfamiliar, you are advised particularly to read other pages in this series before use, most particularly the General Introduction  -  see also the navigator bar at the top of the page, and the list of useful links at the bottom.

If you are unsure of the format for inputting data, hovering the pointer over an input will bring up a short message describing the format expected.  In general:

  • Latitudes, longitudes, grid and magnetic variances can be entered as decimal degrees or DD:MM:SS.  In both cases, southern and western values can be entered as negative or by appending S or W, northern and eastern as positive or by appending N or E.
  • Other angles should be entered as decimal degrees.
  • Time values for the Sun can be entered as 24 hour HHMM or HH:MM, or as 12 hour HH:MM AM or PM.  Seconds values will also be accepted and included, but most published calculations for the Sun are only given to the nearest minute, and greater accuracy than that should not be assumed.
  • All other data such as grid references and post codes should be entered in their normal format.  Irish grid references should be flagged with a leading I.

UK Place Name look up covers UK mainland only.  UK Post Code look up should find codes for the entire UK, but to reduce the chances of usage capping by Google, does so by searching the OpenSpace UK mainland database first, only trying Google on failure.  Other post codes and places, for example Eire, can be looked up using the World Place Name option, but the database is very US-centric, so append an appropriate country name, for example ,Eire.

The correct non-standard skews for the Hot Bird and Astra satellites, respectively +3.5 & +7.5°, are given, accompanied by yellow warning text  hovering the pointer over the field will display an appropriate message, including the standard skew normally expected.

When you are satisfied with your settings, you can save them by pressing Submit and then bookmarking, marking as a favourite, the resulting URL, the parameters in which will recreate your original settings in the calculator.  You may wish to do this once you have positioned a map exactly on your dish site as described below (though you will then have to wait for everything to reload).

Clicking on a map button fixes latitude and longitude as the method of designating the dish location, and creates a map with a marker and azimuth (direction) line for aligning it.  Dragging the marker to a new location recentres the map(s) and updates the calculator.  Likewise, where necessary, changes in the calculator will be reflected in the map(s).  After creating a map, changing settings other than receiver latitude & longitude, or choosing a different satellite, is not recommended and may not be possible.

The Google map has four choices of base layer selectable by clicking the buttons in the top right hand corner.  Satellite pictures take significantly longer to load, so it's quickest to use Map to get as close as possible to the intended final location and zoom level before switching to Satellite or Hybrid.  If you plan to print the map, please read the Notes.

Satellite images are often subject to perspective distortion, to an extent significant in the context of aligning a satellite dish, thus making their results potentially less reliable than the initial impression given by their appealing simplicity.  Work entirely from ground level  position the marker at the point on the ground beneath the proposed dish siting, and choose as aiming point a landmark the base of which is crossed by the line.

For UK mainland nations, there is also an option to create an OS map.  OS's OpenSpace® on-line mapping covers UK mainland down to street level (other UK nations are covered by other agencies and are either only available via OS at low-scale or not at all).  If, despite the coordinate vetting, you manage to create a map of somewhere not actually covered, the map may just show nothing, or stick on an area on the north east coast, in which case Ctrl-Click the map button to remove it, and just use the Google one.  Coordinate conversion between Lat/Lon and E/N doesn't use OSTN02™, so coordinate readouts should only be considered accurate to around 5m.

Notes

  • Satellite and rotor data is now loaded as JSONP, so users attempting to use this page via online language translation services should no longer see messages that *.xml files could not be loaded.
  • Magnetic variance is computed by the 2015 World Magnetic Model, with estimated error less than 1° until 2020.  Thereafter it will display in red, indicating the model's increasing unreliability over time, in which case you should attempt to get a more recent estimate for your location and enter it manually:
  • Browser compatibility notes (see also the next note about printing):
    • ALL  -  Maps gobble up resources.  If you create both types of map together without letting one complete before starting the other, or, after creating maps, many times change settings in the calculator or drag and zoom forcing continual redrawing, you may find that the Google map becomes blank, or there are jumbled tiles or holes in the OS map, or markers disappear from it, perhaps first from the print preview, then from the map proper.  Such problems may resolve themselves given enough time, but now there is also an option to remove a broken map by Ctrl-Clicking the relevant button, so it can be then be clicked again to redraw from scratch.  However, particularly as Google Maps do not document a destroy function, it is questionable whether all the resources used are reclaimed when a map is removed, and, especially if you want to print the maps, you may have to reload the page with your chosen final settings, most easily done by clicking Submit on them, before creating one map at a time, allowing each to load fully before creating the next.
    • FF  -  This page does not support really old legacy versions, but any version including and after 12 that has been tested has proved to work.
    • IE  -  Google's policy of only supporting the latest three versions of any browser means that any version of IE prior to 8 cannot run this page.
    • Opera  -  The oldest legacy versions cannot be supported, but v12 seems to work as long as an Opera inbuilt extension is turned off  about:config, Extensions, EcmaScriptJIT needs to be disabled.  Of the newer Webkit versions, only 43 has been specifically tested and shown to work, but Webkit browsers generally are known to work.
  • Each map is designed to print on a single page of A4 or Letter with top and bottom margins of about 15mm and side margins of about 10mm.  This site has better map printing support than many, but generally printing web content is too often neglected, not least by those who create browsers, and maps particularly so.  In the past I've reported problems to Microsoft, Opera, Google, and OpenLayers, yet problems remained long outstanding, though recent testing has shown a marked improvement in some browsers.
    • ALL  -  Print the Google Satellite Base Layer without the labels.  The latter tend to look fine in Print Preview but prevent the map printing properly.  IE8+ & FF3+ may print them properly, but legacy browsers tend to print only the label & map overlay, without the satellite imagery.
    • FF3  -  Printing individual map pages results in blank maps, you have to print the entire document to get the maps to print properly. Fixed in v3.5.1.
    • IE  -  continues its abysmal history printing maps  of the versions still actually supported by Google, IE8/9 won't print either map correctly, IE10/11 will only print the Google map correctly.
    • Chrome  -  Earlier versions may insert spurious blank pages.
    • Safari  -  Earlier versions may not print the Google Map  please upgrade to the latest version.
    • Opera  -  Legacy version map printing was abysmal; Webkit versions have not been specifically tested, but see the notes above about Chrome and Safari.

Apologies for these inconveniences.

Use decimal degrees or Degrees : Minutes : Seconds?

 
Where is the receiving dish?
 
 
 
 
 
 
 
 
 
System Type?
 
 
 
 
How to find azimuth?
 
 
 
 
 
How to find dish elevation?
 
 
 
 
 
 
 
 
 
Alignment Settings
TargetMeridian Sat:
Azimuth:
 
GridMag Azim:
 
Rotor Azim:
 
Elevation:
 
Skew:
 
Rotor & Dish:
Azimuth:
 
GridMag Azim:
 
Tilt:
 
90 - Tilt:
 
Declination:
 
Elevation:
 
Skew:
 
        

Many thanks to:

Significant updates to this document
Date Description
12/03/2017 Updated page help on browsers, minor supporting script changes.
13/02/2017 Updated with the latest satellite data.  Updated Google Maps authentication.
20/12/2014 Updated World Magnetic Model script with WMM2015 coefficients and test answers.  Added navigation history controls to Ordnance Survey map.
07/12/2014 Updated site OpenLayers script to allow future implementation of navigation history controls.
04/07/2014 Corrected Ordnance Survey map panning problem for all browsers except IE.
19/03/2014 Restored proper printout in IE10+, and by setting IE7 standards to IE8/9.
23/02/2014 Corrected: legacy IE markers, world place names not looking up properly, degree symbol in DMS mode.
06/02/2014 Corrected printing problems, updated Notes concerning Internet Explorer problems.
01/02/2014 HTML5, Google, OpenLayers, & OpenSpace map updates, data and form script updates, updated satellite data.
04/10/2011 Added 'universal' option for offset calculation.
05/09/2011 Improved form option locking when maps are drawn.  Refinements to site OpenLayers script.
21/07/2011 Updated satellites list.
12/01/2011 Updated satellites list.
27/10/2010 Fixed bug loading DMS values from URL.
11/10/2010 To reduce risk of Google usage capping, altered UK Post Code search to try OpenSpace first, then Google.  Significant rewrite of asynchronous script loading.  Cut down OpenLayers script and enabled compression for faster loading.
26/06/2010 Fixed bug in reading URL parameters when DMS set.  Fixed to work using static data only with common translation engines.
13/06/2010 Added support for Chrome and Safari.  Updated Notes appropriately, and to cover Opera 10 hang up.
28/04/2010 Greatly improved support for IE8 wrt map drawing and printing.  Updated site scripts for better form handling and asynchronous data loading.  Updated satellite data.  Added this update record.
01/12/2009 Updated site script handling forms.  Updated satellite data.
13/08/2009 Google Map converted to use Google API, rather than OpenLayers API.  Upgraded Ordnance Survey map to use OpenLayers v2.8.  Fixed problem with colours in <Select> elements in the forms in Opera and IE8.  Improved marker dragging and update of calculator.  Updated satellite data.
06/01/2009 First major useable version in its current form.