How to use a solar compass to point satellite dish azimu

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  1. 1. How to use a Solar Compass Page 1 of 3 Farmskys How to use a solar compass to point a satellite dish, Azimuth & Elevation & other tools I hope you find this Solar Compass satellite pointing guide both practical and useful. Pointing a satellite dish is always quite a challenge first time up. Azimuth is the horizontal component of a direction (compass direction), measured around the horizon, usually from the north toward the east, clockwise measured in degrees. The correct calculation (within 1 degree) of a satellites azimuth is actually quite difficult. The use of a compass can be confusing with magnetic deviation to consider, as well as the many other factors that may influence erratic behavior of that little magnetic needle. So here is a dead certain method of obtaining an accurate azimuth (as long as the sun shines) from which you can extrapolate any other azimuth. Or you could even use the moon, if that works for you! What do I need? You will need accurate time and access to the internet. Using the 'Solar compass' link (at 2.) below enter the place name in Australia or enter your locations accurate lat/long and the date and time you wish to take the reading. UTC offset is calculated for you. The closer you undertake this to midday, the closer to north your reading will be. Use a vertical pole to cast a shadow and mark the solar azimuth (degrees) of the shadow. If this is done on a clear flat surface, you can then extrapolate any other azimuth with a simple protractor. You can use this same calculator to actually confirm or point a dish to a particular satellite (as long as the sun shines) by fiddling the time and date until the solar azimuth matches your satellites azimuth. Hold your breath that the sun is shining at that time and the sun will 'fully illuminate' your dish i.e. your dish will point directly to the sun's azimuth. This picture shows a C1 installation at the calculated time. You'll just have to trust me that I'm not fibbing. Oh and you still have Elevation to complete, but that should be a piece of cake now. Tips The sun at the autumn and spring equinoxes describes the exact same arc as the Satellite Clarke belt; in winter you aim higher, in summer lower. Draw a string from the centre of your dish to project the azimuth of your dish for more accurate pointing. Gorbtrack & Satellite Antenna Alignment (below) include excellent solar compass tools.
  2. 2. How to use a Solar Compass Page 2 of 3 Some useful Satellite Stuff URLs (the URL links are clickable and work at 10/06) 1. Magnetic variation (current magnetic compass deviation for your location in Australia) 2. Solar Compass (a very accurate means of determining azimuth) 3. Australian Place Names Locator (Lat/Lon) 4. View of the Earth from a satellite (just for fun) 5. Traditional internet based satellite Azimuth/ Elevation calculators. Try the Satlex calculator or Satsig (for an Aussie & NZ map based calculator) or try Satsig Polar Mount for good polar mount calculations. a) The Satlex satellite locator gives you a diagrammatic representation of the satellite you are locating and lnb skew and a .csv file of pointing data for every satellite viewable from the location you entered. b) The skew for Optus series satellites (and a few other Ku satellites) is not standard, so the results here may not be accurate. 6. EIRP (dBW) vs dish size C-band 7. EIRP (dBW) vs dish size Ku-band Note: Very handy to work out what size dish you need for the transponder your trying to tune. It has a good margin of error. often supports a beam feature. Click on the beam column and it may provide the EIRP pattern for that transponder. Optus provides pretty hopeless EIRP data for its series of satellites. 8. Antenna Alignment Software (free for personal use) Satellite Antenna Alignment is a nice, but very basic piece of freeware (personal use is free). Load it up on the PC and it gives a nice text az/el (only) view of all satellites viewable from your place, plus a solar compass plotter. It also has a useful offset antenna calculator. SMLink is a Swedish equipment providers free alignment software. It is quite sophisticated in some areas, particularly if you are calculating link budgets, carrier to noise and antenna gains. A worthwhile inclusion (check out the Swedish Christmas trees). Gorbtrack is the complete PC satellite alignment tool. Load this excellent freeware on to your PC and your set for your geo-stationary satellite life. It has data update options (to keep up to date with recent satellites) and a reasonable (US based) Australian place name database (albeit with some odd spelling).
  3. 3. How to use a Solar Compass Page 3 of 3 Gorbtracks inbuilt solar compass function is a true gem. I love it! And the diagrammatic views are priceless. Highly recommended! 9. "Ricardo's Geo-orbit Quick look" is the complete internet satellite compendium. 10. Solar Interference Calculator (calculates times of geo-stationary satellite solar interference). Interesting. Note: a) Solar interference is what happens when the sun lines up right behind the satellite youre locked onto. The sun is a rather large u-wave radio source; so goodbye satellite reception for 4-6 minutes for 4-6 days, twice a year at the Spring and Autumnal equinoxs. Here we can calculate when it will happen for your location and satellite. Enter a value of 1 degree for Max. Separation (e.g. 1.0 deg). This will produce a valid result. 11. Detailed Satellite Mathematical Calculations (if youve a yearn for link budgets, dish gains & dBs n things), this site is outstanding. 12. Confused about your polar mount? Have a look here for a comprehensive guide. The standard latitude declination angle table and a Moteck HH how to. Heres another comprehensive guide. 13. Whats an LNB? All about your LNB. Universal, dual-polarity, C, Ku. Its all here. 14. What's a Satellite Band? 15. Whats a Geostationary Orbit? Understanding microwaves and satellite bands. 16. Whats an Offset Dish? Offset dish elevation angle set up and pointing. 17. How do I align a Toroidal dish? If youre setting-up one of these its worth a visit to learn how at this handy NZ based site. The Satlex T90 calculator is a true gem. Best to lign up on the centre of the bit of sky you want to view. 18. Austech members Solar Compass success story.


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