[amsat-bb] Re: maximum AO-7 distance

Gus 8P6SM 8p6sm at anjo.com
Mon Oct 1 18:43:27 PDT 2012

```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?

--
73, de Gus 8P6SM
The Easternmost Isle
```

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