PCSAT2 TELEMETRY DEFINITIONS AND EQUATIONS 22 Aug 2005
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rev1 12 Dec 2003
rev2 4 Mar 2005
rev3 28 Apr 2005 Swapped Isol and Iload and changed "10" fm Cell1 to Cell2
rev4 22 Aug 2005 swapped Load & Sol current in EQN table to be consistent
and fixed the two Cell-1's to be 1 and 2
This is the validated as-wired telemtry channels for PCSAT2.
The twenty channels of PCSAT2 telemetry are multiplexed into 4 sequential
frames of telemetry. Every telemetry frame consists of 5 analog channels,
8 on/off status bits, two CONTROL bits, two FRAME counter bits and a final
single status bit. It takes four such frames to constitute the complete
telemetry picture of PCSAT2.
The format of each frame is:
PCSAT2>APRTLM,SGATE:T#SSS,111,222,333,444,555,11111111,XXYY,ZZ
Where the header is PCSAT2>APRTLM,SGATE: (These fields may vary)
Within the actual data portion of the packet are these fields:
SSS is the serial number
111 is the first channel telemetry
222 is the second channel
333 is the thrid channel
444 is the forth channel
555 is the fifth channel
11111111 is the status of the 8 ON/OFF OUTPUT commmand bits
XX is the status of the CTRL-A and CTRL-B outputs
YY is the 1-of-4 telemetry FRAME counter (00,01,10,11)
Z is a single telemtery ON/OFF bit.
Notice, the YY bits tell you which frame you have.
Here are the verififed channels for PCSAT2:
YY CHANNEL 1 CHANNEL 2 CHANNEL 3 CHANNEL 4 CHANNEL 5
-- ----------- ----------- ----------- ------------ ------------
00 RXA-current RXB-current BAT-CELL3 TNCA-current TNCB&RXC-Cur
01 BAT-Temp PEC-Temp TXA-current TXB-Current Bat-Cell1
10 TXA-Temp TXB-Temp Bat-Cell2 RX-Temp TLM-Temp
11 Bat-Volts Bat-Current Load-Current Sol-Current 5-Volts
Telemetry equations are generally of the form y = aX^2 + bX + C where
X is the 3 byte decimal telemetry count in each channel in the data.
For PCSAT2, however, all channels are linear except for the temprature
which are y=.00001X^3 - .0034X^2 + .7134X - 33.49
CHANNEL A B C UNITS Equation basis
------------- ----- ----- ------ ----- ---------------------------
RXA-current 0 2 0 mA a count of 256 = 512 mA
RXB-current 0 2 0 mA a count of 256 = 512 mA
BAT-CELL3 0 0.0498 0 volts
TNCA-current 0 2 0 mA a count of 256 = 512 mA
TNCB&RXC-Cur 0 2 0 mA a count of 256 = 512 mA
BAT-Temp . .. . degC See cubic equation above
PEC-Temp . .. . degC See cubic equation above
TXA-current 0 5 -5 mA a count of 256 = 1.33 Amps
TXB-Current 0 5 0 mA a count of 256 = 1.33 Amps
Bat-Cell1 0 0.0504 0 volts
TXA-Temp . .. . degC See cubic equation above
TXB-Temp . .. . degC See cubic equation above
Bat-Cell2 0 0.0500 0 volts
RX-Temp . .. . degC See cubic equation above
TLM-Temp . .. . degC See cubic equation above
Bat-Volts 0 0.1 0 volts
Bat-Current 0 -22.44 +2842 mA a count of 128 is 0
Load-Current 0 15.43 20 mA a count of 128 is about 2000 mA
Sol-Current 0 7.843 -7 mA a count of 128 is about 1000 mA
5-Volts 0 0.0235 0 volts a count of 213 = 5 volts
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PCSAT2 TELEMETRY DESCRIPTION 4 Mar 2005
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Not realizing I had done all this work, I did another complete write up
of the telemetry from scratch. Here is the new version and this one is
derived from the actual code in our PCSAT2 decoding software used
during all testing. So if there is any difference between the above
file and the below file, I guess the below file should take precedence.
Define Function for Temperature:
Tof(V) = .00001 * V ^ 3 - .0034 * V ^ 2 + .7134 * V - 33.49
Telemetry Format is: T#515,135,134,001,138,001,11111111,0010,1
T#nnn is serial number
Then five 3 byte decimal values
Then eight bits which default to 11111111
1st bit = 0 means 96 hour timer toggle is set
2nd bit = 0 forces reset of opposite TNC
3rd bit = 0 means RX heaters are on
4th bit = 0 means VHF transmitter is enabled
5th bit = 0 toggles state of Shunt Reference
6th bit = 0 means PSK-31 is enabled
7&8 bits= 01 means FM Repeater is forced on
00,11,10 mean nothing
Next is a comma
Next is SRFF,Z
Where S bit is Solar Experiment Reset
Where R bit is RESET 8 hour timer (shuts down system)
Where FF are they two frame bits
IF Frame is "00" THEN
RXa Current = 2 * value1
RXb current = 2 * Value2
B3volts = Value3 / 20.07
TNCa current = 2 * value4
TNCb current = 2 * value5
IF Z bit is a "0" THEN ArmB2 = -1
IF Frame is "01" THEN
BatTemp = Tof(value1)
CaseTemp = Tof(value2)
TXa current = 5 * value3 - 5
TXb current = 5 * value4
B1-volts = value5 / 19.86
IF Z bit is "0" THEN ArmA2 = -1
IF Frame is "10" THEN
TXa temp = Tof(value1)
TXb temp = Tof(value2)
B2-volts = value3 / 20.01
RX temp = Tof(value4)
TNC temp = Tof(value5)
IF Z bit is "0" THEN ArmB1 = -1
IF Frame is "11" THEN
B4-volts = value1 / 10
Bat current = INT(-22.44 * value2) + 2.27 * Tf + 2842)
Load current = INT(15.43 * value3 + 20)
Solar current= INT(7.843 * value4) - 7
5volt ref = value5 * 5 / 213
IF Z bit is "0" THEN ArmA1 = -1 ELSE ArmA1 = 0
IF 5volt ref is < 1 volt THEN set 48 hour warning
Notice TF in the Battery Current equation. This is the
temperature of the FTSCE experiment which must be
obtained by other means. Assume 0 deg C if not avail
de WB4APR, Bob