[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: AO-7



I first put this memo out last week, almost nothing came of it, which 
surprised me somewhat.  IF AO-7 if to be made maximally useful to the 
amateur community then we need to achieve some new learning about what AO-7 
can and can not do now in 2002.

There are options of course, the AMSAT community can do nothing and AO7 
will become another long term derelict in the sky like AO-10 has been these 
many years.  [It might surprise some current AMSAT people that there are 
some people (like me specifically) who do NOT see the derelict AO-10 as a 
good situation that brings credit to AMSAT....]

IF however some effort to learn about AO-7 in July and onwards in 2002 
might tell us enough that AO-7 could be put under management and become 
potentially a long term performing resource to the AMSAT amateur 
community.  To do this will require some potential users of AO-7 to do some 
detailed observing and data collection and to report the information 
coherently so that it can be use to assist in further analysis of what 
might be achieved going forwards with AO-7.  The transponders in AO-7 
having lasted this long could now last for many many years.  Done right 
AO-7 is a resource, done wrong (in my opinion) AO-7 becomes a long term 
source of uncontrollable pollution.  As I see it work needs to be done, and 
done starting right now.

Tom Clark, W3IWI pointed out that even finding an exciter that can transmit 
the command information has not yet been achieved, current production 
equipment is not able to do the trick it seems.

Tom, the Intel 4004 was introduced in 1971 and I finally had one with 256 
bytes of EPROM and 1024 bytes of 256 x 4 ram in mid 1973 when the first 
microprocessor commands were sent to AO-6.  The 4004 was really just a 
supper clock program that had trip events (to send commands to AO-6).  The 
program was written entirely in hand assembled machine code and was some 
950 bytes long.  The 8080 came along in 1974 and Randy and I had cloned 
8080's working reliably in late 1974/early 1975.

Tom, you might also remember that RCA's Dr. Winder slipped me a two chip 
CDP1802 set and a few weeks later some extras arrived at AMSAT HQ, this of 
course led to the 1802 design for IPS.

now for a repeat of my earlier memo with a few minor additions......

Greetings:

I have now recovered some of the early notes I kept on AO-7 after it was 
launched.  It would be very helpful if those of you who are active on AO-7 
now would look carefully for the following conditions.

When AO-7 is in MODE A, look for MODE B to be on at the same time.
When AO-7 is in MODE B, look for the 435.1 beacon to be on at the same time.
If this NEVER happens then we know the mutual lock out logic is working, or 
at least we can have a sense it is working properly

If these undesirable conditions were to exist, and with truly random logic 
states they could exist, they might indicate why some of the worst FMing 
and other aberrations in the signals might be explained to some degree.

IF things inside the control logic are really waking up in a random state, 
then one should also hear whatever is going on inside the CODESTORE box 
coming out the telemetry ports on occasion.  This would mostly be 
meaningless garbage BUT it should be repetitive at least two or three times 
over a regular overhead pass of AO-7.  If you hear what seems like random 
garbage coming out the transponder beacon signals please record it and look 
for a repetitive cycle in the data.

There should also be some occasional 45.4545 baud data coming out of the 
telemetry ports.  On the Transponder beacons this will be space only 
keying, NOT FSK keying, and will sound funny.  Thanks to G3RWL for 
remembering this can be a valid mode of operation.

Last but certainly not least, observations, on multiple frequencies at 
once, at the TURN ON, ie when AO-7 enters sunlight, made carefully would be 
of great interest.  The 435.1 beacon has special logic internally that is 
supposed to prevent the beacon from coming ON when the power supply and the 
ON/OFF beacon control signal line wake up at the same time.  This was a 
major design effort and was tested here for many months and many hundreds 
of thousands of cycles.  The timing capacitor to effect this delay was a 
very high quality unit and was NOT of the electrolytic type - it should not 
have failed.  It would be immense interest if we could find out if the TURN 
ON where the MODE A transponder beacon came ON and the 435.1 beacon came ON 
occurred at the same time or with an offset in time.  The offset in time 
could be as little as 300 milliseconds but should be well over 1 second.

The deaths of OSCAR VI and VII were very different.  OSCAR VI died because 
of cell degradation but this was mitigated by most of the control logic 
having fluxed up into the never never region above a logic "0" and below a 
logic "1".  Control simply became impossible.  Late in life we regularly 
shut AO-6 OFF for periods to let the logic drain down.

I have been reviewing my notes of that time and I never remember nor do my 
notes show any apparent flux up logic being an issue with AO-7!  I am sure 
there was no difference by intent between the two satellites yet there is a 
serious difference between the two satellites.  If anyone has any thoughts 
on this I would appreciate some thoughtful discussion on the subject.

There is a continuing need for very careful and ongoing analysis and 
observation of the way that AO-7 is operating.  It is only with new 
knowledge of what exists inside AO-7 that will tell those interested what 
can be done and what might be done with the existing state of the bird.  I 
urge those with resources to make observations and very detailed notes on 
what is observed.  The sequence of events, including time references can be 
very valuable.

Last, but not least, if the control logic is waking up truly randomly then 
2.3 GHz beacon should be coming up as well from time to time.  Those of you 
with AO-40 resources should be able to hear this signal.  Reports of this 
event would be of great interest to many.  The beacons, 435.1 MHz and the 
2.3 GHz beacon may well be involved in the heavy FMing of the Transponder 
signals.  Observations are needed.

For the moment I am watching this reflector for any relevant observations 
of AO-7.

Larry
VA3LK

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home