(Insert in 625-205, Galileo Orbiter Functional Requirements Book) Custodian: R. Johansen APPROVED: Spacecraft System ________________ Engineer: N. Yarnell Spacecraft System ________________ Software Engineer: R. C. Barry Engineering ________________ Manager: R. J Reichert GLL Downlink ________________ System Engineer: R. Johansen JET PROPULSION LABORATORY No. GLL-3-280, Revision D 1 March 1989 SUPERSEDES: GLL-3-280, Revision C 13 January 1986 FUNCTIONAL REQUIREMENT GALILEO ORBITER TELEMETRY MEASUREMENTS AND DATA FORMATS Revised and Rewritten _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ page 1 of 389 GLL-3-280 Rev. D A2.4 AACS POSITION AND RATE DATA The AACS shall provide pointing vector and rate data. The pointing vector information shall be provided in the Earth Mean Equator (EME) 1950.0 coordinate system, the Ecliptic (ECL) 1950.0 coordinate system, and spacecraft relative coordinate system. The LRS data schematic is shown in Figure A2.4.1 and described further in Table A2.4.1. __________________________________________________________________________________________ | EME - 50 COORDINATES | | | ECL - 50 | S/C RELATIVE | | | | |COORDINATES| COORDINATES | |________________________________| | |___________|____________________| |ROTOR ATTITUDE|PLATFORM ATTITUDE|PLATFORM RATE| ROTOR | ROTOR | | | | | | | SPIN | SPIN | | | |______________|_________________|_____________| MOTION | POSITION | CONE | CLOCK | |RA | DEC|TWIST|RA | DEC | TWIST | CONE| CROSS | DELTA | ANGLE | POSITION| POSITION | | | | | | | | | CONE | | | | | |16 | 16 | 16 |16 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | 16 | |___|____|_____|___|_____|_______|_____|_______|________|___________|_________|__________| Figure A2.4.1. AACS Position and Rate Data GLL-3-280 Rev. D Table A2.4.1. AACS Position and Rate Data __________________________________________________________________________________________ | |Bits | | | | Data Description |Frame|Data Start| Comments(1) | |___________________________|_____|__________|___________________________________________| | Rotor Attitude (2) | | |The Least Significant Bit (LSB) | | Right Ascension (RA) | 16 | 0 |represents 1/2 revolution. | | Declination (DEC) | 16 | 16 | | | Twist (3) | 16 | 32 | | | | | | | | Platform Attitude (2) | | |The Least Significant Bit (LSB) | | Right Ascension (RA) | 16 | 48 |represents 1/2^16 revolution. | | Declination (DEC) | 16 | 64 | | | Twist (4) | 16 | 80 | | | | | | | | Platform Rate | | |The LSB represents 1/2^24 revolution | | Cone | 16 | 96 |during 8-1/3 millisecond interval. | | Cross Cone | 16 | 112 | | | | | | | | Rotor Spin Motion Delta | 16 | 128 |The LSB represents 1/2^24 revolution | | | | |during 8-1/3 millisecond interval. | | | | | | | Rotor Spin Position | 16 | 144 |The LSB represents 1/2^16 revolution | | Angle (2, 5) | | | | | | | | | | Cone Position (2, 6) | 16 | 160 |The LSB represents 1/2^16 revolution | | Clock Position (2, 7) | 16 | 176 | | |___________________________|_____|__________|___________________________________________| | Notes: | |(1) Data is a 16 bit 2's complement number. | |(2) Data is predicted ahead to RTI 0. | |(3) Rotor twist represents rotation about the spacecraft Z-axis. The twist | | angle shall be defined as the angle from the projection of the Earth's | | North Pole onto the X-Y plane to the Rotor -X-axis (positive rotation | | about the Z-axis provides a positive twist angle.) | |(4) Platform twist represents rotation about the scan platform boresight | | (L- axis). The twist angle shall be defined as the angle from the | | projection of the Earth's North Pole onto the M-N plane to the scan | | platform -M-axis (positive rotation about the L-axis provides a | | positive twist angle. | |(5) Spin position angle represents the angle from the projection of the | | North Ecliptic Pole vector on the x-r plane to the -X-axis. Positive | | rotation about the Z-axis provides a positive spin position angle. | |(6) Cone position represents the null offset corrected encoder angle | | between the -Z-axis and the scan platform boresight (L-axis). An | | increasing encoder reading represents an increasing +N rotation of the | | scan platform with respect to the stator. | |(7) Clock position represents the null offset corrected angle between the | | -Y-axis of the rotor and the SAS shaft (-N-axis nominally the -Y-axis | | of the stator). An increasing encoder reading represents an | | increasing -Z rotation of the rotor with respect to the stator. | |________________________________________________________________________________________| 257 GLL-3-280 Rev. D A2.7 MAGNETOMETER SUBSYSTEM TELEMETRY These paragraphs describe the format and content of the output of the Magnetometer Subsystem. A2.7.1 MAG Packet. The schematic of a MAG Packet is shown in Figure A2.7.1. One packet is placed in each LRS frame. ___________________________________________________________ | Instrument | 1st Science | 2nd Science | 3rd Science | Title | Status | Sample | Sample | Sample | | | | | | Data Offset | 0 | 16 | 64 | 112 | | | | | | Bits/packet | 16 | 48 | 48 | 48 | | | | | | Description | A2.7.3 | A2.7.4 | A2.7.5 | A2.7.6 | |____________|______________|______________|______________| Figure A2.7.1 MAG Packet A2.7.2 Instrument Synchronicity. The contents of the MAG Packet can be uniquely determined from the data within the packet and the SCLK Mod 91 count. The MAG Synchronization Index is equal to the SCLK Mod 91 count. A2.7.3 Instrument Status. The contents of the Instrument Status section are two bytes of subcommutated analog and digital status values. This is shown in Table A2.7.1. The positions are shown relative to synchronization index in Table A2.7.2. Table A2.7.1 Instrument Status (MSB is bit 1) Bit(s) Measurement Contents ________________________________________________________ ----------- |1-8|Most significant 8 |8 MSB's of | | | |bits of subcommu- |subcommutated | | | |tated instrument |data | ______|______ | |status data. | | _|_____________|_ |___|_____________________|_____________________________| |1|2|3|4|5|6|7|8| MAG Byte #1 ________________________________________________________ ----------- |1-8|Most significant 8 |8 MSB's of | | | |bits of subcommu- |subcommutated | | | |tated instrument |data | ______|______ | |status data. | | _|_____________|_ |___|_____________________|_____________________________| |1|2|3|4|5|6|7|8| MAG Byte #2 298 GLL-3-280 Rev. D TABLE A2.7.2 Instrument Status Subcommutated Data Sl MEASUREMENT CONTENTS ____________________________________________________________________ | 0 | Current Scale Factor |0000000000000010= Inboard sensor | | | | high (+/-16 KnT) | | | |0000000001000000= Inboard sensor | | | | low or Outboard sensor high | | | | (+/-512 nT) | | | |0000100000000000=Outboard sensor | | | | low (+/-16 nT) | | | |ALL OTHERS ARE U/A | |_____|__________________________|_________________________________| | 1 |MAG select and gain select|0101XXXXXXXXXXXX(*)= Outboard | | | | sensor on | | | |1010XXXXXXXXXXXX= Outboard sensor| | | | off | | | |XXXXXXXX0101XXXX= Inboard sensor | | | | on | | | |XXXXXXXX1010XXXX= Inboard sensor | | | | off | | | |XXXX0101XXXXXXXX= Outboard sensor| | | | gain high | | | |XXXX1010XXXXXXXX= Outboard sensor| | | | gain low | | | |XXXXXXXXXXXX0101= Inboard sensor | | | | gain high | | | |XXXXXXXXXXXX1010= Inboard sensor | | | | gain low | | | |ALL OTHERS ARE N/A | |_____|__________________________|_________________________________| | 2 |Current flip positions |11100001XXXXXXXX= Outboard sensor| | | | flipped right | | | |00011110XXXXXXXX= Outboard sensor| | | | flipped left | | | |XXXXXXXX11100001= Inboard sensor | | | | flipped right | | | |XXXXXXXX00011110= Inboard sensor | | | | flipped left | | | |ALL OTHERS ARE N/A | |_____|__________________________|_________________________________| | 3 |Last flip command |11100001XXXXXXXX= Outboard sensor| | | | commanded right | | | |00011110XXXXXXXX= Outboard sensor| | | | commanded left | | | |XXXXXXXX11100001= Inboard sensor | | | | commanded right | | | |XXXXXXXX00011110= Inboard sensor | | | | commanded left | | | | | | | |ALL OTHERS ARE U/A | |_____|__________________________|_________________________________| (*) where X is irrelevant 299 GLL-3-280 Rev. D TABLE A2.7.2 Instrument Status Subcommutated Data Sl MEASUREMENT CONTENTS ________________________________________________________________________ | 4 | Calibrate enable/flip |XXXXXXXX01010101= Calibrate power on | | | power enable |XXXXXXXX10101010= Calibrate power off| | | |00001000XXXXXXXX= Flipper power | | | | on (start flipper power | | | | decrements from 1000 to 0000. | | | | A step occurs at every MOD 91 | | | | count) | | | |00000000XXXXXXXX= Flipper power off | | | |ALL OTHERS ARE N/A | | 5 | Gain 1 |-2 to +1.999939 | | | Gain 2 |-2 to +1.999939 | | 7 | Gain 3 |-2 to +1.999939 | | 8 | Offset 1 | Field Units | | 9 | Offset 2 | Field Units | | 10 | Offset 3 | Field Units | | 11 | Rotation 11 | -1 to +0.9999695 | | 12 | Rotation 12 | -1 to +0.9999695 | | 13 | Rotation 13 | -1 to +0.9999695 | | 14 | Rotation 21 | -1 to +0.9999695 | | 15 | Rotation 22 | -1 to +0.9999695 | | 16 | Rotation 23 | -1 to +0.9999695 | | 17 | Rotation 31 | -1 to +0.9999695 | | 18 | Rotation 32 | -1 to +0.9999695 | | 19 | Rotation 33 | -1 to +0.9999695 | | 20 | Despin status |01010101XXXXXXXX= Despin on | | | |10101010XXXXXXXX= Despin off | | | |ALL OTHERS ARE N/A | | 21 | S/C time | 16 MSB's of RIM | | 22 | S/C time | 8 LSB of RIM. and MOD 91 count | | 23 | Spin angle | spin angle as received from CDS | | 24 | Spin delta angle | spin delta as received from CDS | | 25 | Xdspin at 21 | Field Units | | 26 | Ydspin at 21 | Field Units | | 27 | Zdspin at 21 | Field Units | | 28 | Calibration coil |01010101XXXXXXXX= on | | | |10101010XXXXXXXX= off | | | |ALL OTHERS ARE N/A | | 29 | Optimal averager/ |01010101XXXXXXXX= Optimal | | | snapshot data status | averager on | | | |10101010XXXXXXXX= Optimal | | | |averager off | | | |XXXXXXXX01010101= Snapshot data on | | | |XXXXXXXX10101010= Snapshot data off | | | |ALL OTHERS ARE N/A | | 30 | Memory keep alive volt | -20 V. to +19.9993900 V | | 31 | +12 Volts DC | -20 V. to +19.9993900 V | | 32 | +10 Volts DC | -20 V. to +19.9993900 V | | 33 | -12 Volts DC | -20 V. to +19.9993900 V | |_____|__________________________|_____________________________________| 300 GLL-3-280 Rev. D TABLE A2.7.2 Instrument Status Subcommutated Data Sl MEASUREMENT CONTENTS ________________________________________________________________________ | 34 | Reference V+ | -20 V. to +19.9993900 V | | 35 | Reference Gnd | -5 V. to +5 V. | | 36 | Temperature Electronics | -5 V. to +4.9998475 V. | | 37 | +V - Clip | -5 V. to +4.9998475 V. | | 38 | -V - clip | - 5 V. to +4.9998475 V. | | 39 | Parity error counters | MSByte=H/W. LSByte=S/W | | 40 | XNF | Field Units | | 41 | YNF | Field Units | | 42 | ZNF | Field Units | | 43 | spare | | | 44 | spare | | | 45 | spare | | | 46 | DSP-Constant | | | 47 | Aver # | | | 48 | spare | | | 49 | spare | | | 50 | Xo aver | Field Units | | 51 | Xo Sin 0 aver | Field Units | | 52 | Xo Cos 0 aver | Field Units | | 53 | Yo aver | Field Units | | 54 | Yo Sin ~^ aver | Field Units | | 55 | Yo Cos 0 aver | Field Units | | 56 | Zo aver | Field Units | | 57 | Zo Sin 0 aver | Field Units | | 58 | Zo Cos 0 aver | Field Units | | 59 | spare | | | 60 | ROM checksum pointer | 0 to 4000 | | 61 | ROM checksum | LSByte=o to 255 | | 62 | RAM checksum pointer | 16384 to 20480 | | 63 | RAM checksum | LSByte=0 to 255 | | 64 | ROM CKSUM (POR) | CKSUM $0000 - $OFFF | | 65 | RAM CKSUM (POR) | CKSUM $4000 - $46FF | | 66 | S/C time | 16 MSB's of RIM | | 67 | S/C time | 8 LSB of RIM and MOD 91 count | | 68 | Spin angle | spin angle as received from CDS | | 69 | Spin delta angle | spin delta as received from CDS | | 70 | Xdspin aver at 66 | Field Units | | 71 | Ydspin aver at 66 | Field Units | | 72 | Zdspin aver at 66 | Field Units | | 73 | Data buffer beginning |4800 (HEX) to 4D00 (HEX) | | | address | | | 74 | Data buffer | Field Units | | 75 | Data buffer | Field Units | | 76 | Data buffer | Field Units | | 77 | Data buffer | Field Units | | 78 | Data buffer | Field Units | |_____|__________________________|_____________________________________| 301 GLL-3-280 Rev. D TABLE A2.7.2 Instrument Status Subcommutated Data Sl MEASUREMENT CONTENTS ________________________________________________________________________ | 79 | Data buffer | Field Units | | 80 | Data buffer | Field Units | | 81 | Data buffer | Field Units | | 82 | Data buffer | Field Units | | 83 | Data buffer | Field Units | | 84 | Data buffer | Field Units | | 85 | Data buffer | Field Units | | 86 | Data buffer | Field Units | | 87 | Data buffer | Field Units | | 88 | Data buffer | Field Units | | 89 | Data buffer | Field Units | | 90 | Command counter | Set to zero at each | | | | POR | |_____|__________________________|_____________________________________| A.2.7.3.1 Data Buffer Format. The data provided in the OPTIMAL AVERAGING and SNAPSHOT modes of the magnetometer is stored in a data buffer provided between locations 48DO-4D00. This data includes the current storage pointer start time sector data and 200 vector samples of the magnetic field in the OPTIMAL AVERAGER MODE. In the SNAPSHOT mode the data is stored in reverse order due to timing restrictions in the interrupt handling routines and includes the start time and 210 vector samples. Format details are provided in Table A.2.7.3. This data is read out in 16 16-bit blocks once each MOD91 frame from address 4800-4D00 and placed in the magnetometer subcommutated data from Sl=74 through Sl=89. (see Table A.2.7.2). In order to collect one complete buffer of data approximately 40 frames must be read. The data readout continuously cycles bet~een addresses 4800-4D00. 302 GLL-3-280 Rev. D TABLE A.2.7.3 MAG DATA BUFFER CONTENT OPTIMAL AVERAGER SNAPSHOT ________________________________________________________________________ |Memory |Memory | |Location |Location | | | | | | | | 4800 8 MSB of X @ T |4800 8 LSB Sensor 3 data @ T | | o | 209 | | 4801 8 LSB of X @ T |4801 8 MSB Sensor 3 data @ T | | o | 209 | | 4802 8 MSB of Y @ T |4802 8 LSB Sensor 2 data @ T | | o | 209 | | 4803 8 LSB of Y @ T |4803 8 MSB Sensor 2 data @ T | | o | 209 | | 4804 8 MSB of Z @ T |4804 8 LSB Sensor 1 data @ T | | o | 209 | | 4805 8 LSB of Z @ T |4805 8 MSB Sensor 1 data @ T | | o | 209 | | . . | . . | | . . | . . | | . . | . . | | 4CAA 8 MSB of X @ T |4CE6 8 LSB Sensor 3 data @ T | | 199 | o | | 4CAB 8 LSB of X @ T |4CE7 8 MSB Sensor 3 data @ T | | 199 | o | | 4CAC 8 MSB of Y @ T |4CE8 8 LSB Sensor 2 data @ T | | 199 | o | | 4CAD 8 LSB of Y @ T |4CE9 8 MSB Sensor 2 data @ T | | 199 | o | | 4CAE 8 MSB of Z @ T |4CEA 8 LSB Sensor 1 data @ T | | 199 | o | | 4CAF 8 LSB of Z @ T |4CEB 8 MSB Sensor 1 data @ T | | 199 | o | | | | | 4CEC Current storage pointer | | | | | | 4CFO 16 MSB of RIM (SCLK) |4CF3 8 LSB of RIM and MOD91 | | | | | 4CF2 8 MSB of RIM and MOD91 |4CF5 16 MSB of RIM (SCLK) | | | | | 4CF4 S/C Spin Angle |4CF7 8 MSB of MOD91 | | | | | 4CF6 S/C Spin Motion Delta | | |_______________________________|______________________________________| In the "Optimal Average" mode timing between vectors is controlled by the AVERAGE # found in SI47 of the instrument status data. The timing is always a multiple of the MOD91 timing and is defined by DELTA T = (AVERAGE # + 1) *60.6666 In the "Snap Shot" mode timing between vectors is 33.3 ms or 30 vectors per second. 303 GLL-3-280 Rev. D A2.7.4 1st Science Sample. The 1st Science Sample section contains 3 (16 bit) samples of sensor data collected exactly 1 MOD 91 count prior to the SCLK MOD 91 count of the LRS frame they are within. The 3 (16 bit) samples are 3 measurements corresponding to the X Y and Z axis respectively. The measurements are output in field units which can be converted to nano-teslas (nT) by dividing by the scale value provided in the instrument status (Sl=0, Table A2.7.2). FieldnT = (FieldFu)/SCALE (*) (*) SCALE shall be commandable to a selected value. Each sample is a 16 bit two's complement word which ranges from 32768 to +32767 A2.7.5 2nd Science Sample. The 2nd Science Sample section contains 3 (16 bit) samples of sensor data collected at 222.22 ms after the MOD 91 count prior to the SCLK MOD 91 count of the LRS frame they are within. The 3 (16 bit) samples are 3 measurements corresponding to the X, Y, and Z axis respectively. The measurements are output in field units which can be converted to nano-teslas (nT) by dividing by the scale value provided in the instrument status (Sl=0, Table A2.7.2). FieldnT = (FieldFu)/SCALE Each sample is a 16 bit two s complement word which ranges from 32768 to +32767 A2.7.6 3rd Science Sample. The 3rd Science Sample section contains 3 (16 bit) samples of sensor data collected at 444.44 ms after the MOD 91 count prior to the SCLK MOD 91 count of the LRS frame they are within. The 3 (16 bit) samples are 3 measurements corresponding to the X, Y, and Z axis respectively. The measurements are output in field units which can be converted to nano-teslas (nT) by dividing by the scale value provided in the instrument status (Sl=0, Table A2.7.2). FieldnT = (FieldFu)/SCALE Each sample is a 16 bit two's complement word which ranges from 32768 to +32767 A2.7.7 Telemetry Mode Changes. Upon the application of system power MAG shall automatically configure itself to a standby mode. MAG data packets will contain no valid data in this mode. Commanded telemetry mode changes are processed every RIM. 304