Satgen 500  Mobile Phone Problems by GM4IHJ  (BID SGEN500) 1998-10-24

Since writing Satgen485 in July, the satellite mobile phone saga has
taken a few unexpected turns. Orbcom have finally got their full
complement of 28 store and forward sats in LEO orbits These message
sats follow the pattern set years ago by radio amateur satellites
Uplink 148 to 150 MHz.Downlinks 137.46 1 D ;137.6625 1 D;137.6875 2 E
; 137.7175 5 D ;137.7375 1 E;137.8 2 E, where numeral after frequency
is no. of sats heard that frequency, and D = day time orbits, E
signifies evening orbits. Extra sats go up in 1999. Orbcoms success
reveals how well the high altitude aircraft assisted launches of their
Pegasus/Taurus winged rockets, are going.

Iridium has so far been less successful. 84 of the Motorola group LEO
mobile phone sats are now in orbit. Why they need 84 ? When the
designed fleet was 64, is not clear. But their original September 98
operational date has not been met, and is presently postponed , at
least until November 98.

Equally unhappy are the Globalstar consortium. They recently lost 12
satellites when a Russian Zenith rocket failed to get them into orbit.
Even worse the Odyssey series of satellites will not now be launched.
The proposal did not get the start up capital necessary , and it has
been abandoned.

Meanwhile, when everyone thought they were out of the race, the
geostationary satellite designers have come up with what looks like a
reasonable design using a very big dish antenna on the proposed
satelite. Thereby overcoming the objection, that the extremely long
path ( up to 20 times the longest LEO path) would require too much
power, and hence was unsuitable for battery powered mobile handsets.

All is not yet clear however for Iridium. India started the shift when
their Radio Astronomers realised that in order to get Iridium to be
"helpful", they need only persuade their goverment to deny licenses
for Iridium ground stations in India - ground stations being essential
if one wishes to connect to the local terrestrial network. European
radio astronomers then took up the problem and the situation at Oct 98
is - Iridium will cease all operation likely to cause interference
around 1612 MHz on 1 Jan 2006. Replacing existing satellites with
satellites which cause no radio interference. In addition European
radio astromers have not yet agreed to limit operations, pointing out
that Iridiums suggestion of a night time window cleared for astronomy
, neglects the fact that radio stars keep sidereal time , and appear
during the day and the night, in a pattern over which the astronmers
have no control.

Perhaps there is a very interesting lesson here for radio amateur
facing potential extinction from massive LEOsat interference. The
Achilles heel of all these systems is that their ground stations must
get local goverment licenses. It is no longer the case that "Get one
goverment to agree , and the rest must accept these intrusions".
PS. Grateful thanks to all who sent greetings for the publication of
the 500th edition of this saga. Will now have a beer to celebrate