[amsat-bb] SUNSAT Telemetry

[Bob Bruninga <bruninga@xxxxxxxxxxxxx>]

Here is how to interpret SUNSAT APRS Status and Telemetry packets:

>OBC1v8: up=20/01:49:17, rst=wdog, Tue Oct 10 11:18:06 UTC 2000
 
FIELD1:	On Board Computer software version 
FIELD2:	Up time in Days, Hours, Minutes and Seconds
FIELD3:	Reason for the last RESET ( POWER-ON, TELECOMMAND, or WATCHDOG)
FIELD4:	Onboard Clock Time

The SUNSAT APRS telemetry is sampled once every 4 minutes.  Thus, in 24 
samples, you get a full 98 minutes of data which constitues one orbit.  
To give whole orbit data, the 24 sample telemetry buffer is transmitted
one packet every 9.6 seconds so that a complete set can be received in
just 4 minutes.  THus the 000 packet is the current value and each
subsequent one is the previous 4  minute one:
 
SUNSAT-3>APRS:T#000,098,133,140,041,046,11100000
SUNSAT-3>APRS:T#001,099,138,110,041,038,11111111
SUNSAT-3>APRS:T#002,099,140,191,042,040,11111100... etc

Telemetry data is identified by a T# header , then a serial number, then 
5 analog telemetry channels, and then 8 Binary Bits. 

SERIAL#:	Whole Orbit buffer pointer (0 in the first example above),
CHANNEL1:	Battery state of charge percent (98 %)
CHANNEL2:	Battery voltage in 10ths of a volt (13.3 V)
CHANNEL3:	Battery charge current -128 in 10's of Milliamps  
                (140 - 128)*10 = 120 ma
CHANNEL4:	Battery temperature in degrees C (41 øC),
CHANNEL5:	Top plate sun sensor reading (46, an uncalibrated value).  
BINARY BITS:	The last field indicates the state of the 8 solar panels
                (0: sourcing the power bus, 1: shunted, dumping energy).

The above telemetry was when SUNSAT was over Arkansas and it was just sunrise in 
Maryland.  Thus SUNSAT was in daylight even though Arkansas was in dark.

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