sdfin [ parameter=value ... ] [ outputfile ... ] sdfin [ parameter=value ... ] [ directory ]
Parameters are: on_pass_disk, tape_device, pass_number, files_per_pass, pass_date, pass_time, satellite, hi_res, temp_units, use_master, master_file, start_time, fine_lines, fine_samples, smth_lines, smth_samples, sync_time, debug_time, time_diag, max_gap, sat_time_test.
sdfin creates TeraScan Optical Line Scanner (OLS) datasets from the Defense Meteorological Satellite Program (DMSP) stored data fine (SDF) telemetry.
Input telemetry data can be read from the pass disk, tape, or standard UNIX disk files. Multiple passes on tape or the pass disk can be processed at once. In the case of UNIX disk files, additional "header" information needs to be provided by the user to process the pass.
The OLS sensor data is composed of two channels: a visible and a thermal channel. The image data from each of these channels has approximately the same spatial resolution (< 0.5km). The data resolution is 6-bits and is stored as byte data.
The parameter hi_res gives the user two options which determine how sdfin is to extract and store the data. For an input pass that contains 5*M lines and 5*N samples of data, the following describes the extraction options available:
lines samples
---------------
hi_res=yes:
5*M 5*N
no subsampling or averaging
hi_res=no:
M N
average every five pixels in scan direction
subsample every fifth row
The overall spatial subset of the OLS data to be extracted can be specified in one of two ways:
1) the smallest rectangular area required to cover a region defined by a master dataset (see master).
2) a rectangular area of specific size, beginning at a user-specified time and scan sample.
There are no (user-supplied) input TeraScan datasets. The sources for input telemetry data are described above. Output is either to a user supplied directory or a user-supplied list of dataset names. If a directory name is entered, output names will be automatically generated and the files will reside in the specified directory. Names will be generated that look like f#.yyddd.hhmm.ols, where # is the DMSP satellite number, yyddd is the year and julian date, hhmm is the start hour and minute of the output dataset. If a directory name is not entered, the output filename(s) given will be used with the type of dataset appended to the end of the file.
In processing the telemetry data, sdfin looks for a "good" time value to attribute to the start of the pass. A time is considered "good" when three consistent and consecutive times have been found. This "good" time helps ensure that sdfin begins processing after any "noise" at the beginning of the pass. More importantly, it allows the earth location of the data to be performed more accurately.
In establishing a "good" start time, sdfin first tries to use the satellite times embedded in the telemetry. If they cannot be extracted for some reason, sdfin will then use the time in the pass header that was put in by the operator (see parameters sync_time, time_diag, max_gap, debug_time, and sat_time_test below).
Answer yes if the input is from the pass disk, or no if the input is from tape or standard UNIX disk file.
Valid responses are [yes or no]. The default is yes.
If on_pass_disk=no, this is the name of the input tape device or UNIX disk file name. Tape device names are machine specific. For example, the following devices are commonly used on the Sun SPARC Station:
/dev/nwd0 - DAT, fixed blocking, APUNIX driver /dev/nrwd0 - DAT, variable blocking, APUNIX driver /dev/nsx0 - 8mm, fixed blocking, APUNIX driver /dev/nrsx0 - 8mm, variable blocking, APUNIX driver /dev/nrmt - 8mm or CCT, variable blocking, SUN driverAll of the above device names imply no rewind on close.
The default is extracted from the UNIX environment variable TAPE. Only tape devices listed in the file $PASSDIR/devtable, or simple UNIX disk file names, are accepted.
This specifies the number(s) of the pass(es) to process, when input is from tape or the pass disk. Passes are numbered starting with 1. Input tape is always assumed to be positioned at the first pass.
Valid responses for input from the pass disk are [1 to maximum number of passes that can be stored on your pass disk (see lspass]. The default response is the number of the last acquired pass.
Valid responses for input from tape are [1 to 100]. The default response is 1.
If input is from tape, this is the number of tape files per pass. If files_per_pass=2, then each pass is assumed to consist of a header file, followed by a data file. If files_per_pass=1, then the tape is assumed not to have any header files. In this case, the user must supply the additional "header" info using the three parameters listed immediately below.
Valid responses are [1 or 2]. The default response is 2.
If files_per_pass=1 or the pass is from a UNIX disk file, this is the date of the pass to be processed. See formats for valid date formats.
If files_per_pass=1 or the pass is from a UNIX disk file, this is the start time of the pass to be processed. See formats for valid time formats.
If files_per_pass=1 or the pass is from a UNIX disk file, this is the DMSP satellite name of the pass to be processed.
Valid responses include [f-8, f-9, f-10, f-11].
This determines how sdfin extracts and stores the data. The different options are described above in the DESCRIPTION.
Valid options are [yes or no]. The default is no.
Specifies the temperature scale of the OLS thermal calibration. The thermal calibration comes from a fixed scaling determined before launch.
Valid options are [kelvin celsius fahrenheit]. The default is celsius.
Answer yes if the OLS data is to be selected from the intersection of a master dataset (number 1 in the description above, also see master). Answer no if subsets are to be specified by start time and sample (number 2 in description above).
Valid responses are [yes or no]. The default is yes.
If use_master=yes, this is the name of the master dataset used to specify a region for OLS data extraction (see master).
Valid responses are any TeraScan dataset that contains a map projection-based earth transform. The default is Master.
If use_master=no, this is the start time for OLS data extraction. The first line with a time greater than start_time is the first OLS output line. A response of 00:00:00 instructs sdfin to begin processing at the first scan line.
Any valid time is allowed (see formats). The default is 00:00:00.
If use_master=no and hi_res=yes, this is the number of fine OLS lines to be written to the output OLS dataset. If the end of pass is detected before the output dataset is complete, the output dataset is truncated.
The valid range is [>=1]. The default is 2000.
If use_master=no and hi_res=no, this is the number of subsampled OLS lines to be written to the output OLS dataset (see DESCRIPTION). If the end of pass is detected before the output dataset is complete, the output dataset is truncated.
The valid range is [>=1]. The default is 2000.
If use_master=no, this is the first sample to extract from the pass. Samples are numbered starting with 1.
The valid range is [1 to 7322] if hi_res=yes. The valid range is [1 to 1464] if hi_res=no. The default is 1.
If use_master=no and hi_res=yes, then this is the number of fine samples written to the output set.
The valid range is [>= 1 <= 7322]. The default is 7322.
If use_master=no and hi_res=no, then this is the number of smoothed samples written to the output set.
The valid range is [>= 0 <= 1464]. The default is 1464.
OPTIONAL. Instructs sdfin to print out the embedded times it encounters in processing the telemetry.
Valid responses are [yes or no]. The default value is [no]. This parameter can only be set by an explicit specification on the command line.
OPTIONAL. Specifying yes instructs sdfin to try and find a good start time for the pass using the times embedded in the telemetry. Specifying sync_time=no, instructs sdfin to bypass the satellite times and use the operator given time (the time in the pass header).
The default value is yes. This parameter can only be set by an explicit specification on the command line.
OPTIONAL. Determines whether sdfin prints diagnostic messages regarding time gaps in the telemetry and the insertion of missing data.
Valid responses are [yes or no]. The default value is [yes]. This parameter can only be set by an explicit specification on the command line.
OPTIONAL. This specifies the number of seconds that is to be considered a valid time gap in the telemetry stream. If a time gap occurs that is less than this time, sdfin attempts to insert the proper amount of "missing" data. If a time gap occurs that is more than this time, sdfin assumes the apparent time gap is caused by a bit error in the time word and ignores it.
Valid responses are integers [> 0]. The default value is [90]. This parameter can only be set by an explicit specification on the command line.
OPTIONAL. This is the number of seconds to search for valid satellite times at the beginning of the pass.
The default value is 90. This parameter can only be set by an explicit specification on the command line.
$TSCANROOT/refdata/satel/f-*/orbdata $TSCANROOT/refdata/satel/f-*/ols
dmsp, ols, datasets, formats, etx, avin, rdsin, rtdin, magnify, subsamp, fixline, master.
An attribute called telemetry is written to OLS output datasets to distinguish datasets derived from rtd, rds, sds and sdf telemetries.
Warning: In the later stages of the F-9 spacecraft, the OLS thermal data went out of specification and the temperatures may be incorrectly calibrated. Correction tables are available that can be applied to correctly calibrate the data if necessary.
DMSP Data Specifications, IS-YD-821B, 7 March 1991. DMSP Processing Guide, Aerospace Corporation, El Segundo, CA.
Last Update: $Date: 1998/05/29 20:42:48 $