The following two fields form the VIDF comment block. This block is a free form set of text generally used for any and all documentation of the VIDF. Some common features in comment blocks include: a change log, pertinent publication list, instrument description, and algorithm definitions. Also found here are listings of the contents of packed VIDF sensors which often cannot be adequately broken out in the restricted space provided in the VIDF description block. The UDF kernel software makes no active use of these fields.
This is a scalar field which specifies the number of lines of text in the comment field.
The field begins with the line format id s followed by an integer specifying the number of comment lines. An optional comment field may follow.
Sample NUMBER OF COMMENT LINES field:s 77 /* Num Comments */
An array field of length Number of Comment Lines, this field constitutes the VIDF comment area. Each element in the array is a line of text not to exceed 79 characters in length. If the number of comment lines has been given as 0 then this field is then undefined and is entered in the VIDF as a null line.
The comment field begins with the array designation line: m followed by the input N 1. Here N is the total number of entries and should be set to the value given in the Number Of Comment Lines field and 1 indicates that each element in the array will occupy its own line. Each of the following N lines begins with the line format t followed by a line of text not to exceed 79 characters. An optional comment field may be added to the end of each line.
Sample COMMENT BLOCK field:m 77 1 /* Comments */ t IMAGE:IMAGE-1:HENA:HENASCI:IMHACCUM /* C000 */ t /* C001 */ t The High Energy Neutral Atom (HENA) experiment is a part of the /* C002 */ t Imager For Magnetopause to Auroral Global Explorer (IMAGE) /* C003 */ t spacecraft. The experiment constructs images of the earth's /* C004 */ t magnetosphere using energetic neutral atoms. The experiment /* C005 */ t has two sensors, one emphasing high-spatial resolution and the /* C006 */ t other emphasing high energy resolution. /* C007 */ t /* C008 */ t This UDF definition contains the HENA accumulator data. In /* C009 */ t addition to hardware that presents valid events to the DPU, /* C010 */ t there is hardware that counts the various pulses that are /* C011 */ t generated in the detectors. Because of false triggers and noise /* C012 */ t these accumulators count many more pulses than are genuine /* C013 */ t events. There are 16 of these accumulators, each 24 bits long, /* C014 */ t compressed to 10 bits before transmission. /* C015 */ t /* C016 */ t The data is stored in 32 bit sensors, three 10-bit measurements /* C017 */ t per sensor. The data must be unpacked before uncompressed. Both /* C018 */ t the unpacking of the data and uncompression are handled through /* C019 */ t tables contained in this VIDF /* C020 */ t /* C021 */ t The measurement locations within the five defined UDF sensors /* C022 */ t are defined in the following table /* C023 */ t /* C024 */ t MEASUREMENT SEN BITS | MEASUREMENT(S) SEN BITS /* C025 */ t ______________ ___ _______ | ______________ ___ _______ /* C026 */ t Start Fast 0 20-29 | Stop Fast 1 20-29 /* C027 */ t Start Shaped 0 10-19 | Stop Shaped 1 10-19 /* C028 */ t Start Coinc 0 0-9 | Stop Coinc 1 0-9 /* C029 */ t MCP TOF 2 20-29 | SSD Pileup 3 20-29 /* C030 */ t Coinc 2 10-19 | TOF SSD 3 10-19 /* C031 */ t Energy Rate 2 0-9 | Full MCP 3 0-9 /* C032 */ t Full SSD 4 20-29 | SSD TOF 5 20-29 /* C033 */ t Valid Rate 4 10-19 | /* C034 */ t Transfer Event 4 0-9 | /* C035 */ t /* C036 */ t The following is a list of tables found in this VIDF: /* C037 */ t /* C038 */ t TABLE 0: Decompression table for 10 bit compressed data /* C039 */ t TABLE 1: Byte Mask for bits 0-9 /* C040 */ t TABLE 2: 10 bit shift right /* C041 */ t TABLE 3: 20 bit shift right /* C042 */ t /* C043 */ t To break out the individual data fields do the following table /* C044 */ t operations: /* C045 */ t /* C046 */ t Bit Field: apply TABLE(S) with OPERATION(S) /* C047 */ t --------- -------- ------------ /* C048 */ t 0-9 1 5 /* C049 */ t 10-19 2,1 7,5 /* C050 */ t 20-29 3,1 7,5 /* C051 */ t /* C052 */ t The following can be extracted from this UDF /* C053 */ t /* C054 */ t VALUE: SEN TABLE(S) OPERATION(S) UNITS /* C055 */ t ______________ ___ _______ ____________ ______________ /* C056 */ t Start Fast 0 3,1,0 7,5,0 counts/accum /* C057 */ t Start Shaped 0 2,1,0 7,5,0 counts/accum /* C058 */ t Start Coinc 0 1,0 5,0 counts/accum /* C059 */ t Stop Fast 1 3,1,0 7,5,0 counts/accum /* C060 */ t Stop Shaped 1 2,1,0 7,5,0 counts/accum /* C061 */ t Stop Coinc 1 1,0 5,0 counts/accum /* C062 */ t MCP TOF 2 3,1,0 7,5,0 counts/accum /* C063 */ t Coinc 2 2,1,0 7,5,0 counts/accum /* C064 */ t Energy Rate 2 1,0 5,0 counts/accum /* C065 */ t SSD Pileup 3 3,1,0 7,5,0 counts/accum /* C066 */ t TOF SSD 3 2,1,0 7,5,0 counts/accum /* C067 */ t Full MCP 3 1,0 5,0 counts/accum /* C068 */ t Full SSD 4 3,1,0 7,5,0 counts/accum /* C069 */ t Valid Rate 4 2,1,0 7,5,0 counts/accum /* C070 */ t Transfer Rate 4 1,0 5,0 counts/accum /* C071 */ t SSD TOF 5 3,1,0 7,5,0 counts/accum /* C072 */ t /* C073 */ t To return same values but as raw telemetry - omit the last /* C074 */ t table and operation for each line above. /* C075 */ t /* C076 */