In general, a constellation of spacecraft is used to broadcast to a
particular region with high angles of view in order to reduce blockage or
shadowing. A constellation of a plurality of spacecraft is placed in
24-hour orbits having inclination of about 55.degree., eccentricity of
about 0.32, semi-major axis of about 42,000 km, longitude of the ascending
node of about 43.degree. East, argument of perigee of about 270.degree.,
and longitude of the ground track at maximum latitude of about 7.degree.
East. The preferred number of spacecraft ranges from three to six. In a
particular application of Digital Audio Broadcast to Europe in some
embodiments, the most populous cities are provided with service from no
more than about 10.degree. from vertical, and broadcast takes place when
the spacecraft are above at least 35.degree. North latitude. The broadcast
power is reduced during those portions of the orbit in which the ground
track lies in the Southern hemisphere.
