PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 1997-01-13 NOTE = "This is a format description of Galileo PWS reformatted full-resolution spectrum analyzer (lrs) archive files. This information is reproduced in PDS structure in associated 'safull.fmt' files." END_OBJECT = TEXT END Notes on full-resolution Galileo PWS LRS archival format The Galileo PWS full-resolution LRS data are organized into the following archival format for ease of use. Each 600-byte fixed-length record contains data from available minor frames in a 28-minor-frame instrument cycle. During this cycle, all available frequencies are sampled and two snapshots of waveform data are taken. Items named "validity flags" are derived from the 8-bit data quality (DQ) word in the PWS minor frame which contains even parity bits corresponding to the associated data items. All multi-byte binary items are "big-endian" or high-byte-first unless noted otherwise. Bits are numbered starting with 0 as the least significant (lowest order or rightmost) bit up to 7 as the most significant (highest order or leftmost) bit for 8-bit bytes or, for example, up to 31 for 4-byte binary items. HEADER SECTION, 44 bytes byte offset description ------ ----------------------------------------------------------------------- 0 32-character string like "GO PWS 1992-12-16T00:00:00.000Z\0" where the numbers represent the SCET of the beginning of the interval (28 minor frame cycle) in PDS time format and the last character is ASCII null "\0" (binary zero). SCLK marking the beginning of a 28-minor-frame interval of PWS data 32 3-byte binary SCLK RIM count (24-bit unsigned range: 0 - 16777215) 35 1-byte binary SCLK minor frame count (modulo 91 counter: 0 - 90) 36 2-byte spare SCET corresponding to above SCLK 38 2-byte binary days since January 1, 1958 40 4-byte binary millisecond of day (0 - 86401999, for 2 leap seconds) TIME-ORDERED STATUS SECTION, 52 bytes byte offset description ------ ----------------------------------------------------------------------- 44 32-bit minor frame presence flags. In general, minor frame presence is indicated by a 1 in the corresponding bit position. hexadicimal value 00000001 indicates only the first minor frame is present, while 08000000 indicates only the 28th minor frame is present, and 0FFFFFFF indicates all 28 minor frames are present. 48 32-bit spectrum analyzer antenna switch flags. The antenna switch position is logged for each minor frame and stored in a bit position corresponding to the minor frame modulo 28 counter, as in the previous item. Normally this will be hexadecimal 00000000 for all electric field minor frames or 0FFFFFFF for all magnetic field minor frames. 52 Array of 7 8-bit command words obtained during the 28-minor-frame cycle. A complete 8-bit command word is obtained for each 4 consecutive minor frames: Bits 7 and 6 are obtained during the first minor frame, bits 5 and 4 during the second minor frame, bits 3 and 2 during the third minor frame, and bits 1 and 0 during the fourth minor frame. The bits are specified as follows: +---+---+---+---+---+---+-------+ | 7 | 6 | 5 | 4 | 3 | 2 | 1 0 | PWS 8-bit command word +---+---+---+---+---+---+-------+ bit description bit = 0 bit = 1 --- --------------------------------- -------------- --------------- 7 waveform command enable inhibit 6 sa antenna switch e/b electric magnetic 5 sa antenna switch cyc/inh cycle inhibit 4 calibration inhibit enable 3 waveform select electric magnetic 2 waveform power on off 1-0 2-bit waveform receiver mode (0 - 3) 00 = waveform survey (alternating 1kHz and 10kHz snapshots) 01 = 25200 4-bit samples per second (50Hz - 10kHz mode) 10 = 201600 4-bit samples per second (80kHz mode) 11 = 3150 4-bit samples per second ( 5Hz - 1kHz mode) 59 Array of 7 8-bit WBR automatic gain control (AGC) Indicates gain of wideband receiver. Can be used to calibrate WBR data. Relative to the beginning of the record (28-minor-frame interval), the individual AGC sample times occur at -0.467s (-7 RTI) and every 2.667s (40 RTI) thereafter (where an RTI is one tenth of the minor frame interval). 66 Array of 7 8-bit power supply monitor (PS MON) Indicates health of instrument. Nominal value is 204 +/- 2. Relative to the beginning of the record (28-minor-frame interval), the individual PS MON sample times occur at +2.0s (+3 RTI) and every 2.667s (40 RTI) thereafter (where an RTI is one tenth of the minor frame interval). 73 Array of 7 8-bit "8-bit ADC REF" Indicates health of 8-bit analog to digital converter. Nominal value is 55 +/- 2. Relative to the beginning of the record (28-minor-frame interval), the individual "8-bit ADC REF" sample times occur at +0.867s (+13 RTI) and every 2.667s (40 RTI) thereafter (where an RTI is one tenth of the minor frame interval). 80 Array of 7 8-bit "4-bit ADC REF" Indicates health of 4-bit analog to digital converter. Nominal value is 102 +/- 2. Relative to the beginning of the record (28-minor-frame interval), the individual "4-bit ADC REF" sample times occur at +1.533s (+23 RTI) and every 2.667s (40 RTI) thereafter (where an RTI is one tenth of the minor frame interval). 87 Array of 7 8-bit analog engineering status validity flags. Four flags are present in each byte: +---+---+---+---+---+---+---+---+ | x x x x | 3 | 2 | 1 | 0 | Analog Eng validity flags +---+---+---+---+---+---+---+---+ bit description bit = 0 bit = 1 --- --------------------------------- -------------- --------------- 3 "4-bit ADC REF" flag invalid valid 2 "8-bit ADC REF" flag invalid valid 1 "PS MON" flag invalid valid 0 "AGC" flag invalid valid 94 2-byte spare FREQUENCY-ORDERED STATUS SECTION, 28 bytes byte offset description ------ ----------------------------------------------------------------------- 96 Array of 4 8-bit spectrum analyzer (SA) validity flags. Each of the 4 channels is sampled 7 times during the record. The validity of the first sample is indicated by bit 0, the second by bit 1, and so on up to the seventh sample by bit 6. A one bit indicates available data that passes the parity check. The four bytes contain flags for the four channels in increasing frequency order from the first channel at 5.62 Hz to the fourth channel at 31.1 Hz. +---+---+---+---+---+---+---+---+ | x | 6 | 5 | 4 | 3 | 2 | 1 | 0 | flag bit position +---+---+---+---+---+---+---+---+ 1 1 1 1 1 1 1 SA channel 1 . . . +---+---+---+---+---+---+---+---+ | x | 6 | 5 | 4 | 3 | 2 | 1 | 0 | flag bit position +---+---+---+---+---+---+---+---+ 4 4 4 4 4 4 4 SA channel 4 100 Array of 4 32-bit sweep frequency receiver (SFR) validity flags. Each individual channel of the SFR is sampled only once during the record. These flags are grouped by filter bank of which there are four of 28 channels each, ordered by increasing frequency. The first 32-bit group contains validity flags for the lowest frequency bank and the fourth 32-bit group contains flags for the highest frequencies. The flags are arranged in each 4-byte element (32-bit group) such that the lowest frequency is represented by bit 0 and the highest frequency by bit 27, hence the hexadecimal value 0FFFFFFF in an element indicates valid values for all 28 associated frequency channels. +---+---+---+---+---+ +---+ | x x x x | 27| . . . | 0 | validity flag bit position +---+---+---+---+---+ +---+ 28 . . . 1 SFR channels 1 - 28 . . . +---+---+---+---+---+ +---+ | x x x x | 27| . . . | 0 | +---+---+---+---+---+ +---+ 112 . . . 85 SFR channels 85 - 112 116 Array of 2 32-bit high frequency receiver (HFR) validity flags. The lowest 14 HFR channels are sampled twice each and the upper 28 HFR channels are sampled once each during the record interval. The first 4-byte element contains pairs of flags for each of the lower 14 HFR channels and the second 4-byte element contains individual flags for each of the upper 28 HFR channels. A 1 bit indicates available data which passes the parity check. +---+---+---+---+---+---+ +---+---+ | x x x x | 27| 26| . . . | 1 | 0 | flag bit position +---+---+---+---+---+---+ +---+---+ 14 14 . . . 1 1 HFR channels 1 - 14 +---+---+---+---+---+---+ +---+---+ | x x x x | 27| 26| . . . | 1 | 0 | flag bit position +---+---+---+---+---+---+ +---+---+ 42 41 . . . 16 15 HFR channels 15 - 42 LRS DATA SECTION, 196 bytes byte offset description ------ ----------------------------------------------------------------------- 124 Array of 28 8-bit spectrum analyzer (SA) uncalibrated samples. These consist of 7 time-ordered samples for channel 1 followed by 7 samples from channel 2, followed by 7 samples from channel 3, and finally 7 samples from channel 4. Relative to the beginning of the record (28-minor-frame interval), the sample times of the individual channels are: SA channel relative sample time (10 RTI per minor frame) ---------- ----------------------------------------------------------- 1 +1.867s (+28 RTI), repeating every 2.667s (40 RTI) 2 +1.200s (+18 RTI), repeating every 2.667s (40 RTI) 3 +0.533s (+08 RTI), repeating every 2.667s (40 RTI) 4 -0.133s (-02 RTI), repeating every 2.667s (40 RTI) 152 Array of 112 8-bit sweep frequency receiver (SFR) uncalibrated samples. These are arranged from lowest to highest frequency channels. Relative to the beginning of the record (28-minor-frame interval), the sample times of the individual channels are: SFR channel relative sample time (10 RTI per minor frame) ----------- ---------------------------------------------------------- 1+n, 29+n -0.133s + n*0.667s (-02 RTI + n RTI), for n = 0 .. 27 57+n, 85+n -0.467s + n*0.667s (-07 RTI + n RTI), for n = 0 .. 27 264 Array of 56 8-bit high frequency receiver (HFR) uncalibrated samples. The lowest 14 channels are repeated twice, followed by the upper 28 channels: 1, 1, 2, 2, . . ., 14, 14, 15, 16, . . ., 41, 42 Relative to the beginning of the record (28-minor-frame interval), the sample times of the individual channels are: HFR channel relative sample time (10 RTI per minor frame) ----------- ---------------------------------------------------------- 1+n two samples at -0.133s + n*2.667s and +0.533s + n*2.667s (-02 RTI + n*40 RTI and +08 RTI + n*40 RTI), for n = 0 .. 6 8+n two samples at +1.200s + n*2.667s and +1.867s + n*2.667s (+18 RTI + n*40 RTI and +28 RTI + n*40 RTI), for n = 0 .. 6 15+n -0.467s + n*2.667s (-07 RTI + n*40 RTI), for n = 0 .. 6 22+n +0.200s + n*2.667s (+03 RTI + n*40 RTI), for n = 0 .. 6 29+n +0.867s + n*2.667s (+13 RTI + n*40 RTI), for n = 0 .. 6 36+n +1.533s + n*2.667s (+23 RTI + n*40 RTI), for n = 0 .. 6 WAVEFORM SAMPLE DATA SECTION, 280 bytes byte offset description ------ ----------------------------------------------------------------------- 320 Array of 280 4-bit waveform samples collected from the first 14 minor frames of this record. This is a snapshot of contiguous samples. +---+---+---+---+---+---+---+---+ -+---+---+---+---+ | 3 | 2 | 1 | 0 | 3 | 2 | 1 | 0 | . . . | 3 | 2 | 1 | 0 | +---+---+---+---+---+---+---+---+ -+---+---+---+---+ sample 1, sample 2, . . . sample 280 Relative to the beginning of the record (28-minor-frame interval), this waveform sample begins at -0.333s (-05 RTI). 460 Array of 280 4-bit waveform samples collected from the last 14 minor frames of this record. This is a snapshot of contiguous samples. Relative to the beginning of the record (28-minor-frame interval), this waveform sample begins at +9.000s (+135 RTI). ------ 600 bytes total