File: TORUS1:[GLL_RAW.INFO]AACS_CONTENTS_PHASE1.DOC

					Feb 25, 1991 KES
			    Add'l Info, Nov 26, 1991 KES

	The contents of the AACS data files are shown below.
Each file contains records of IDL length associated with a
floating point array of 1132 values.  The first 40 values 
contain the standard header values, in floating point format,
followed by 91 groups of 12 Attitude and Articulation Subsystem
(AACS) values, as listed below.  

	Each record in an .AACS file represents one Major Frame 
(= 60.333 seconds) and there are 91 minor frames (mf) in a Major 
Frame (MjF).  Minor frames are numbered 0 to 90, where each minor 
frame is 0.666 seconds.  The Real Time Interrupt (RTI) clock is 
the next finer time.  The RTIs are numbered from 0 to 9 and are 
therefore 0.0666 seconds.  RTIs are divided into eight divisions
(called the MOD8 clock) and represent 8-2/3 milliseconds.

	Each parameter of the 12 values shown below is 
derived in a single minor frame.  The value is then projected
ahead in time to the next minor frame (for RTI=0).  The CDS
receives the value during that "next minor frame", time tags
it with the time of THAT minor frame, builds the telemetry
block and then represents the telemetry block to the Telemetry
Subsystem.  That all happens in the minor frame for which the AACS
value has been projected.  The result is that the AACS parameters
are absolutely time tagged.

	The maximum resolution for each parameter is as follows:
		1) The Least Significant Bit (LSB) represents 
		      1/(2**16) revolution
                2) The LSB represents 1/(2**24) revolution in a
		      8-2/3 millisencond interval.

	Galileo Functional Requirement document 3-180 describes
the reference systems; and 625-505, Volume XII describes the
AACS measurements.

Reference
XIDL	Fortran		Description                       Range    Resol.
------------------------------------------------------------------------
0-39    1-40		Standard Header

40	41  	^	Rotor attitude -- RA	         (0-360 deg)  1
41	42 	.	Rotor Attitude -- DEC	    (-90 to +90 deg)  1
42	43	.	Rotor Attitude -- TWIST          (0-360 deg)  1
43	44	.	Platform attitude -- RA	         (0-360 deg)  1
44	45	.	Platform Attitude -- DEC    (-90 to +90 deg)  1
45	46    mf=0	Platform Attitude -- TWIST       (0-360 deg)  1
46	47	.	Platform Rate -- CONE       (-90 to +90 deg)  2
47	48	.	Platform Rate -- CROSS CONE (-90 to +90 deg)  2
48	49	.	Rotor Spin Motion Delta	  (assume 0-360 deg)  2
49	50	.	Rotor Spin Position Angle (assume 0-360 deg)  1
50	51	.	S/C Relative Cone		 (0-360 deg)  1
51	52	_	S/C Relative Clock		 (0-360 deg)  1

52-63	53-64		Same as above for minor frame = 1
...
1120-   1121-		minor frame = 90
 1131    1132