[amsat-bb] PCsat Power management

[Bob Bruninga <bruninga@xxxxxxxx>]

Here is a summary of power demand on PCsat:

PCsat low power mode saves us about 35% from RESET mode.  But with some
aggressive commanding during this last power minimum we found an
additional 14% savings by turning off all periodic packets except the bare
minimum.

We don't lose anything, because I have modified our PCSAT Command program
(running on all continents) to transmit the BULLETINS and STATUS from the
ground.  Thus, the users on most continents still see the current status,
but PCsat then does not keep sending them over the other 90% of its orbit
where there are no users.  These packets will look like this:

   OPS-min.  No dark ops please. Command Stn sends.

Here are the numbers which show the whole-orbit average power required to
transmit each kind of packet...  Remember there are two TNC's and both are
dual port, and both can be crossconnected to both transmitters in
fail-safe mode (RESET).  When crossconnected, transmit power is doubled.

 PACKET      1200/9600  DEFAULT X-CNCTD NEW-PLAN  FINAL
 ----------- ---------  ------- ------- -------- ------
 A-TLM every  1/3 min   13 ma    26 ma     1/0   10 ma
 B-TLM every  3/1 min   13 ma    26 ma     1/0   10 ma
 A-BText      3/3 min    7 ma    14 ma     5/0    4 ma
 B-BText      3/3 min    7 ma    14 ma     5/0    4 ma
 A-BLTNS    4@6/6 min   13 ma    26 ma   1@6/0    2 ma
 B-BLTNS    4@6/6 min   13 ma    26 ma   1@6/0    2 ma
 --------------------   ------- ------           ------
 TOTAL XMT LOADS        66 ma   128 ma           32 ma


 UHF RX's               70 ma    70 ma   off      2 ma
 TNC/RX fixed load     140 ma   140 ma   on     140 ma
                       ------   ------          ------
 TOTAL LOADS           276 ma   342 ma          174 ma

User load only occurs over about 10% of the earth, so if user demand about
equals the ALOHA standard of less than say 20% when over the HAM
populations, then the user load is less than 5% of total power budget.
Over the USA, user demand is on that order.  But I dont know what it is
over Europe.

If someone in Europe wants to add up the average user packets-per-minute
over a pass, this will help us guestimate how best to manage the user
load.  Dont send me files, just count packets per minute (not counting
PCsat's own packets).

If User load is low enough, we might be able to go back to night ops..

de WB4APR, Bob



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