Satgen286   Satellites for Education   by GM4IHJ              17 Sept 94
BID of this msg is SGEN286  Please use this BID if you retransmit this msg

We presently have two useful amateur radio satellites for experimenters ,
UO11 and AO17, but no replacements are planned. So now looks like a good
time to start lobbying for either another dedicated Educational satellite
,or, perhaps more realistic, experimental facilities on several new
satellites. These extra facilities need not be a large power drain or a
building problem. A typical experimental satellite uses simple circuitry
and low power, and could therefore be a secondary attachment to a unique
non experiment primary payload.
Clearly there is a major decision to be made , in respect of digital or
analog downlink, and while the former may be more convenient for builders
, it is important to remember that schools do not have large budgets.
Anyone contemplating building a school station has to consider the fact
that a digital system requires the addition of a computer, a modem and
probably trainable antennas costing around 1000 pounds sterling or about
1500 dollars US, over and above the much cheaper hardware fit for an
analog receiving system. So while digisats may suit college sat builders,
our most important group of users, namely pre college youngsters, will 
be unlikely to benefit from them.
There is of course no reason why a digisat could not carry a separate CW
telemetry beacon or a digitalker telemetry broadcast. Either of these
simple ancilliaries could provide up to 20 or 30 different experiments for
school physics groups. Starting with simple doppler and working up to
complex differential doppler, measuring Faraday rotation of polarisation,
monitoring propagation, or, via telemetry, deriving UV, IR, and other
radiation studies, plus solar power system monitoring with satellite spin
measurement and orientation assessment, eclipse studies, battery and
temperature monitoring and a host of other interesting practical
demonstrations of physics, not normallly available for study in any other
way.
What is sure , is that any satellite launched without these features
misses a great opportunity to help and encourage a vital section of our
community. What goes up for a small body of advanced well equiped
technically expert users could with the addition of some simple low power
ancilliary features provide for hundreds more users around the world at
little extra cost in money and enormous gain for amateur radio.
But please keep it simple. Too often amateur radio satellites have
attractive experimental features but spoil them in practical operation .
The classic example of this was revealed a few weeks ago in a discussion
about Phase 3 elliptical orbit doppler . Whereby of 7 hams present all
long term satellite operators , none could answer a question about AO13
doppler, Was his equipment drifting in frequency ?, said one. AO13 signals
had curious doppler on them . None of those present had ever measured AO13
doppler for an orbit and discovered that IT WENT UP IN FREQUENCY , unlike
a LEO sat beacon. An omission which is of course excusable  when you
recognise that AO13 never stays on one frequency long enough to present a
full orbit doppler curve. So hopefully if we can get low power beacon
experiments on new satellites we can have them on continuously . So that
even the old timers can discover, what really goes on, Hi.
73 de GM4IHJ @ GB7SAN