Satgen 164      GATEWAYS TO THE FUTURE   by GM4IHJ           17th May 1992

Scenario 98
The following is a possible scenario for 1998.  Oscar xxx Phase 3D is
above the UK horizon . Station GM44PQ calls the local satellite gateway
GB45GATE, located on vacant land at IBROX , GLASGOW, using AFSK packet.
The gateway replies by packet with a menu reporting Channels Ch1 through
Ch5 occupied. A JA is calling Voice CQ on Ch6. A DL is calling CQ Europe
on packet on Ch7, and Ch8 through Ch12 are unoccupied.
The Scottish ground station replies to the gateway asking for connection
to Ch6, and on being given a link to Ch6, he switches from data to voice,
and begins a QSO with the JA station. In this example the ground station 
and the gateway use simplex AFSK packet and FM voice for their UHF link.
With their exchange being similar to that between a ground station and a
repeater , except that the gateway then connects the GM station to Phase
3D's 10 GHz transponder. Up and downlinks can both be on microwave using a
moderate size dish at the gateway to get a high gain antenna connection to
Phase 3D. The gateway automatically tracks Phase 3D in azimuth and
elevation, and it maintains channel spacing by using the Phase 3D beacon
downlink as a guide to doppler shift. The gateway is unattended , but can
be controlled remotely from a nearby command station.

Discussion
Given something like the above we could rapidly make very effective use of
the Phase 3D microwave bands. Without gateways however - we will probably
lose these bands through lack of international usage, simply because very
few stations can equip for personal microwave access direct to Phase 3D.
Both gateways and personal users can happily coexist on Phase 3D..
There is a wide choice of how the ground station should address the
gateway. It could be done by Voice FM, SSB or Data, with the gateway using
digi voice/ packet. The connection between the ground station and the
gateway can be on any suitable easily accessible, cheaply attainable
amateur band, and it can be simplex or duplex. Channelisation may not be
absolutely necessary but it will be tidier than random access which would
place a larger control protocol burden on the gateway software.
For the up and downlinks , modulation could be any of the prescribed types
There is plenty of choice as to how the initial gateways might be
constructed. We can do preliminary trials on Oscar 13 mode L and S. But we
should tailor our efforts towards producing a common hardware and software
format in order to avoid duplication of effort. Given a proper attack on
the problem now , we should be able to provide Amsat administrators with a
good blueprint for gateways to Phase 3D.
What do other radio amateurs think. Please do not tell me you do not like
it, and you will not use it. No one will be forced to use gateways . But
do remember that if we do not beef up our microwave efforts by using
gateways, you may eventually have no microwaves to work on from your
pristine " Made it all yourself" personal access to Phase 3. Use it, or ,
lose it.
I note AO13 580km perigee. No sign upward recovery. 73 de GM4IHJ @ GB7SAN