[amsat-bb] AO-51 update 2/18/2007

[Andrew Glasbrenner]

The satellite is almost reloaded, and the repeater is back on. There may be 
instances where the repeater is shut off on a pass over the command station 
for the next few days, to allow a higher downlink power on the digital side. 
This will allow the command stations to finish the uploads more quickly.

After a few more pieces of software are loaded, we will begin testing 
everything. Things may be chaotic for a bit so please bear with us as we 
make these improvements.

Some of the upgrades to be tested include:

1) An automatic mode changing scheduler that will allow for unattended mode 
switches at a predetermined time and date. This will be a big relief for the 
command team, as they will not have to be at the controls for every single 
mode change on the schedule.

2) A upgraded PL system that works like this: The repeater downlink 
transmitter will normally be off to conserve power. When a signal with a 
valid PL tone is heard on the uplink, the repeater will power up, and switch 
to no PL required for x amount of minutes. x has yet to be determined. After 
x minutes, the transmitter will shut down and return to a standby state for 
a valid PL. This will allow us to use the PL to conserve power and not have 
the 'logjam' effect that came with the past PL scheme. We will also be able 
to identify intruders to our satellite band while over areas with active 
users.

3) Automatic power control that will increase the downlink power when the 
batteries are charged and there is power to spare. Exact values will be 
determined during upcoming testing.

There were also at least twice as many changes made that related to internal 
housekeeping, telemetry, and command and control. Some of these will be made 
public, and some will not for obvious reasons (command and control). I'm 
very proud of the great job the entire AO-51 team has done on this set of 
upgrades over the past 4 months, and wish to personally thank Mike KE4AZN, 
Jim WD0E, and Gould WA4SXM for their hard work.

Just a little while longer and we'll be back to normal operations.

73, Drew Glasbrenner KO4MA
AMSAT-NA VP Operations