On 10/01/2012 02:47 AM, Bob- W7LRD wrote:
to my AO-7 afictionados...what is the maximum distance one can work edge to edge, and how did you figure that out? 73 Bob W7LRD
Maximum communications distance:
MCD = 2 R arccos [ R / (R + h) ]
where R = Radius of earth (Spherical earth: 6371 Km) h = Height at apogee
(Eq 12.4, Sat. Experimenters Handbook 2nd Ed; Davidoff) All you need is the apogee height for the satellite in question, and a calculator. For AO-7 the apogee height USED to be 1460 Km, and probably hasn't altered much over the years. Therefore:
MCD = 2 * 6371 * arccos [ 6371 / (6371 + 1460) ] = 12756 * arccos [ 6371 / 7831 ] = 12756 * arccos [ 0.8135614864 ] = 12756 * 0.620545318575 = 7915.7 Km (4918.59 miles)
What is the "official" distance?
With a good station, the non-spherical earth working for you at your QTH and hoping for some sub-horizon love, who knows?