PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT PUBLICATION_DATE = 2000-06-13 NOTE = " MAG Data File Parameter Definitions" END_OBJECT = TEXT END MAGNETOMETER SCIENCE RECORD VARIABLES (Binary Table Fields) The following list of variable names are contained in the header of the Binary table extension of the Magnetometer data file created by CFITSIO user routines for PDS compliance. The corresponding definitions will be placed in a separate file, and will not be contained in the PDS label file, or require the generation of PDS keywords. 1. met minimum value - 0 maximum value - 160000000 units - seconds (unsigned) definition - Mission Elapsed Time in seconds for the start of this MAG sample block 2. tdb minimum value - -1.3e+8 maximum value - +6.4e+7 units - seconds (signed) definition - Barycentric Dynamical Time corresponding to MET(1). Barycentric Dynamical Time (TDB) is the independent variable in the equations, including terms for relativity, of motion of the celestial bodies. The solution of these equations gives the rectangular coordinates of those bodies relative to the barycentre (centre of mass) of the solar system. (The barycentre does not coincide with the centre of the Sun but is displaced to a point near its surface in the direction of Jupiter.) 3. dqi minimum value - N/A maximum value - N/A units - N/A definition - Data Quality Index c0 = Data Quality Flag[0=good,1=flagged for quality defects] c1 = Instrument number for FC, CTP and AIU[1 or 2] c2 - c6 = Processing Flags not quality related c7 = CCDS Source[0=VC0, 1=VC1, 2=VC2, 3=VC3] 4. mag_on_off minimum value - 0 maximum value - 1 units - N/A definition - magnetometer electronics power on/off - turn the power to the magnetometer electronics on or off. If the power is turned off, the magnetometer science record currently being constructed is terminated, padded out with zeros, and sent. The DPU turns the magnetometer power on when it starts up cmd opcode 0xf500 ground conversion: 0=off 1=on 5. cal_on_off minimum value - 0 maximum value - 1 units - N/A definition - calibration bias current off or on - turn calibration bia current off or on. The default is no calibration. cmd opcode: 0xf501 ground conversion: 0=off 1=on initial value: 0=off 6. cal_a_d minimum value - 0 maximum value - 1 units - N/A definition - calibrate the A/D converter - the A/D converter in the magnetometer electronics has a calibration mode which should be exercised periodically by command. When the DPU receives the "calibrate A/D" command, it finishes building the current science record and queues it for transmission, then sets the "calibrate A/D" bit in its interface to the magnetometer. While the A/D performs an internal calibration (at least two 20 Hz magnetometer cycles), the DPU discards the garbage serial data which the magnetometer sends. At the end of the calibration, the DPU resets the "calibrate A/D bit" and then resumes normal data collection from the magnetometer on the following cycle. cmd opcode: 0xf502 ground conversion: 0=calibration mode off (normal data collection) 1=calibration mode on (internal calibration) Note: the A/D calibration (described above) can be commanded to occur automatically. A non-zero argument identifies the calibration interval in seconds; zero turns off automatic calibration. The default interval is fifteen minutes. 7. range_man_auto minimum value - 0 maximum value - 1 units - N/A definition - range manual/automatic - select manual or automatic range control. The default is "automatic". The DPU finishes building the current science record before processing thi command. cmd opcode: 0xf505 ground conversion: 0=manual 1=automatic initial value: 1=automatic 8. noise_rej_on_off minimum value - 0 maximum value - 1 units - N/A definition - noise rejection on/off - enable or disable the noise rejection filters. The default is "on". The DPU finishes building the current science record before processing this command. cmd opcode: 0xf509 ground conversion: 0=off 1=on initial value: 1=on 9. sw_anti_alias_filt minimum value - 0 maximum value - 1 units - N/A definition - software anti-alias filters on/off - enable or disable th software anti-alias filter. The default is "on". The DP finishes building the current science record before processing this command. cmd opcode: 0xf50b ground conversion: 0=off 1=on initial value: 1=on 10. manual_range minimum value - 0 maximum value - 7 units - N/A definition - manual range setting - the DPU controls three discrete lines which set the gain of the magnetometer detector front end electronics which sets the range of the sensor. When in manual-range-control-mode, the new range will be used until a new range is set or automatic-range-control mode is entered. When in automatic-range-control mode, the new range will be used until the range control algorithm calculates a new range. The default is range 3. The DPU finishes building the current science record before processing this command. cmd opcode: 0xf506 ground conversion: 0=4nT 1=16nT 2=64nT 3=256nT 4=1024nT 5=4096nT 6=16384nT 7=65536nT for example: there are eight sensitivity ranges - in range 0, a field strength of -4nT to +4nT can be measured. initial value: 3=256nT 11. actual_range minimum value - 0 maximum value - 7 units - N/A definition - actual range - This gives the instrument range index that the magnetometer was actually in for the first point in the current packet. Note that each mag sample record als contains the instrument range. 12. ac_axis_select minimum value - 0 maximum value - 2 units - N/A definition - AC axis select - select the axis used for AC processing. The default is the Z axis. The DPU finishes building the current science record before processing this command. cmd opcode: 0xf50c ground conversion: 0=X axis 1=Y axis 2=Z axis initial value: 2=Z axis 13. rng_chng_more_sens minimum value - 1 maximum value - N/A units - N/A definition - range change rate, more sensitivity (lsbs) - This is the time in MAG internal sample intervals (i.e. 0.05 seconds) that the instrument waits before changing the instrument range to a more sensitive range. This is only active whe the instrument is set to autorange mode. The default value is 1200 samples (i.e. one minute). The value in all three field components must be below 17% of current full scale for the entire wait period to result in an automatic change to a more sensitive range. 14. rng_chng_less_sens minimum value - 1 maximum value - N/A units - N/A definition - range change rate, less sensitivity (lsbs) - This is the time in MAG internal sample intervals (i.e. 0.05 seconds) that the instrument waits before changing the instrument range to a less sensitive range. This is only active whe the instrument is set to autorange mode. The default value is 5 samples (i.e. one quarter of a second). If the value in any one of the three field components is above 87.5% of current full scale for the entire wait period, the instrument will change to a less sensitive range. 15. noise_spike_count minimum value - 0 maximum value - N/A units - N/A definition - noise spike count - number of noise spikes seen during this science record. 16. sample_rate minimum value - 0 maximum value - 10 units - N/A definition - output sample rate = The index for the output sample rate given by the following table. Digital filtering is applied with Nyquist frequency given in (). 0 = 1 sample every 100 seconds (0.5 Hz) 1 = 1 sample every 50 seconds (0.5 Hz) 2 = 1 sample every 20 seconds (0.5 Hz) 3 = 1 sample every 10 seconds (0.5 Hz) 4 = 1 sample every 5 seconds (0.5 Hz) 5 = 1 sample every 2 seconds (0.5 Hz) 6 = 1 sample every second (0.5 Hz) 7 = 2 samples every second (1 Hz) 8 = 5 samples every second (2.5 Hz) 9 = 10 samples every second (5 Hz) 10 = 20 samples every second (10 Hz) 17. mag_dc_dc_curr minimum value - 0 maximum value - 255 units - N/A definition - magnetometer DC/DC current - Value of the current transducer monitoring the current drawn by the magnetometer DC to DC power converter. The conversion to milliamperes is: I_DCDC = 496.68-3.95*mag_dc_dc_curr 18. probe_temp minimum value - 0 maximum value - 255 units - N/A definition - probe temperature - Two's complement value of the temperature transducer monitoring the temperature of the magnetometer sensor. The conversion to degrees Centigrade is: cnt = probe_temp if (cnt.lt.128.0) T_PROBE = 17.7 - 0.55*cnt if (cnt.ge.128.0) T_PROBE = 158.5 - 0.55*cnt 19. mag_elect_temp minimum value - 0 maximum value - 255 units - N/A definition - magnetometer electronics temperature - Two's complement value of the temperature transducer monitoring the temperature of the magnetometer electronics. The conversion to degrees Centigrade is: cnt = mag_elect_temp if (cnt.lt.128.0) T_ELECT = 18.5 +0.6134*cnt if (cnt.ge.128.0) T_ELECT = -138.5+0.6134*cnt 20. dpu_dc_dc_temp minimum value - 0 maximum value - 255 units - N/A definition - DPU DC/DC temperature - Two's complement value of the temperature transducer monitoring the temperature of the magnetometer DC to DC power converter. The conversion to degrees Centigrade is: cnt = mag_elect_temp if (cnt.lt.128.0) T_ELECT = 18.5 +0.6134*cnt if (cnt.ge.128.0) T_ELECT = -138.5+0.6134*cnt 21. record_aborted minimum value - 0 maximum value - 1 units - N/A definition - When value equals 1, science record aborted command sent, science record terminated, zero padded. 22. time_tag minimum value - UNK maximum value - UNK units - N/A definition - time tag - the science housekeeping consists of the real- time housekeeping (except for the magnetic field sample) and a time tag. The housekeeping is sampled at the start of science record collection. The time tag indicates the time of the first magnetometer data sample in the science record, and provides more accuracy than the time tag in the packet header. The time tag is the delta time, in secs./20, of the first sample from the 1 sec. time tag in the packet header. Since the 20 Hz magnetometer clock is independent of the spacecraft 1 Hz clock that provides the MET, the time tag may be incorrect by up to 1/20 of a second. The "calibrate A/D" bit indicates that an A/D calibration was done just before this science record was collected. Since calibrating the A/D causes data collection from the magnetometer to be suspended, a time discontinuity is propagated through the data processing stages; thus, the data in the science record should be regarded with suspicion. 23. x_data minimum value - 0 maximum value - 2**16-1 units - N/A definition - X0-X43 DC field (16 bits each) - a series of 44 X-axis magnetic field values are contained in each record of the science data; each value is sixteen bits. This data is collected during a consistent magnetometer state which is recorded and sent with the sampled magnetic field data. To ensure the consistency of the state, the DPU delays processing commands that effect the state until after the current record is complete. If processing is aborted by the Abort Science Record command or by commanding the magnetometer power off, the aborted record will have a flag set and unfilled data slots will have zeros. 24. y_data minimum value - 0 maximum value - 2**16-1 units - N/A definition - Y0-Y43 DC field (16 bits each) - a series of 44 Y-axis magnetic field values are contained in each record of the science data; each value is sixteen bits. This data is collected during a consistent magnetometer state which is recorded and sent with the sampled magnetic field data. To ensure the consistency of the state, the DPU delays processing commands that effect the state until after the current record is complete. If processing is aborted by the Abort Science Record command or by commanding the magnetometer power off, the aborted record will have a flag set and unfilled data slots will have zeros. 25. z_data minimum value - 0 maximum value - 2**16-1 units - N/A definition - Z0-Z43 DC field (16 bits each) - a series of 44 Z-axis magnetic field values are contained in each record of the science data; each value is sixteen bits. This data is collected during a consistent magnetometer state which is recorded and sent with the sampled magnetic field data. To ensure the consistency of the state, the DPU delays processing commands that effect the state until after the current record is complete. If processing is aborted by the Abort Science Record command or by commanding the magnetometer power off, the aborted record will have a flag set and unfilled data slots will have zeros. 26. ac_data minimum value - 0 maximum value - 2**8-1 units - N/A definition - AC0-AC43 sample (8 bits each) - a series of 44 eight-bit AC measurements from the selected axis are contained in each record of the science data. This data is collected during a consistent magnetometer state which is recorded and sent with the sampled magnetic field data. To ensure the consistency of the state, the DPU delays processing commands that effect the state until after the current record is complete. If processing is aborted by the Abort Science Record command or by commanding the magnetometer power off, the aborted record will have a flag set and unfilled data slots will have zeros. 27. noise_data minimum value -0 maximum value - 1 units - N/A definition - noise/range0-noise/range43 - A series of 44 noise reject indicators and ranges are contained in each science record. Each noise reject indicator and three-bit range is packed into a four-bit field; the noise reject is in the msb and the range is in the lsbs. The record is padded with 48 bits to fill a NEAR CCSDS packet. This data is collected during a consistent magnetometer state which is recorded and sent with the sampled magnetic field data. To ensure the consistency of the state, the DPU delays processing commands that effect the state unti after the current record is complete. If processing is aborted by the Abort Science Record command or by commanding the magnetometer power off, the aborted record will have a flag set and unfilled data slots will have zeros. This flag indicates whether the noise filter identified any internal instrument magnetometer samples for rejection that were used to obtain the current science field values. This flag is set whether the noise rejection is on or off.