chrptin [ parameter=value ... ] [ outputfile ... ] chrptin [ parameter=value ... ] [ directory ]
Parameters are start_conseq, max_chrpt_frames, on_pass_disk, tape_device, pass_number, files_per_pass, satellite, pass_date, channels, fix_missing, max_fix_miss, solar_corr, min_sun_cos, calibrate, temp_units, byte_output, base_temp, temp_step, full_report, geo_correct, delta_line, delta_sample, use_lat_range, min_lat, max_lat, use_master, master_file, start_time, num_lines, num_samples, shared_mem, dim_counts.
chrptin creates TeraScan MVISR (Multichannel Visible and Infrared Scan Radiometer) datasets from CHRPT telemetry data. Input telemetry data can be read from the pass disk, a tape, or standard UNIX disk files. Multiple passes on tape or the pass disk can be processed at once.
The user can specify one or more of the ten MVISR channels to extract from the telemetry data. The data can also be spatially subsampled. The overall spatial subset of data to be extracted can be specified in one of three ways:
The smallest rectangular area required to cover a region defined by a master dataset.
A rectangular area of specific size, beginning at a user-specified time and scan sample.
A rectangular area of specific width, beginning at a user-specified scan sample, and intersecting a user-specified latitude range.
There are no 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 fy#.yyddd.hhmm, where # is the FY 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 name of the file will be used with the type of dataset appended to the end of the file.
OPTIONAL. This specifies the number of consecutive CHRPT frames with respect to time needed to recognize the true start of useful pass data. Consecutive lines must be 1/6 of a second apart, and must also have good sync and matching satellite ids. Note that all but the last two CHRPT frames from this initial sequence are discarded.
Valid responses are [> 2]. The default is 2.
OPTIONAL. Maximum number of CHRPT frames per input satellite pass. The default is 6000 frames, which translates to over 16 minutes of live CHRPT data. This parameter is needed only to process exceptionally long passes taken from satellite recorders. Setting the maximum number of frames greater than 15000 (about 40 minutes of data, a little less than half an orbit) may cause problems when using masters.
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.
Valid responses are [1 or 2]. The default response is 2.
This is the name of the satellite. The default is fy1-c.
If on_pass_disk=no, this is the date [YYYY/MM/DD] that the pass was collected.
The default is today's date.
This is a list of the MVISR channels to extract from the CHRPT pass. The ten channels correspond to 0.58-0.68, 0.84-0.89, 3.55-3.95, 10.3-11.3, 11.5-12.5, 1.58-1.64, 0.43-0.48, 0.48-0.53, 0.53-0.58, and 0.90-0.96 micrometers.
Valid responses are [1,2,3,4,5,6,7,8,9,10]. The default is 1,2,3,4,5,6,7,8,9,10.
Answer yes if the dataset is to have bad or missing lines of MVISR data filled in by duplicating nearby lines. Answer no if the dataset is to contain all bad or missing lines.
Valid responses are [yes or no]. The default is yes.
OPTIONAL. Only if fix_missing=y. The maximum number of sequential missing lines that can be fixed.
Valid response is any positive number. The default is 1.
Determines whether or not to perform the solar zenith angle correction.
Valid responses are [yes or no]. The default is no.
OPTIONAL. Only if solar_corr=y. The minimum value for cosine of sun zenith angle.
Valid response is a real value in the range 0.0 .. 1.0. The default is 0.05.
Answer yes if the MVISR dataset is to be converted to values with engineering units. For channels 1,2,6-10 the units are percent albedo. For channels 3, 4, and 5 the units are brightness temperature. This process is often referred to as radiometrically calibrating the data. New calibration coefficients are computed for each 100 input lines.
The calibration algorithm is based on information provided by the Scientists at the National Satellite Meteorological Center, China Meteorological Administration. Valid responses are [yes or no]. The default is yes.
If calibrate=yes, converts the raw MVISR data to brightness temperatures with units of degrees Celsius, Kelvin, or Fahrenheit.
Valid responses are [celsius, kelvin, fahrenheit]. The default is celsius.
If calibrate=yes, answer yes if the output dataset is to be saved as 8-bit integer data. Radiance percent albedo is converted to 8-bit values by multiplying by 4 and rounding to the nearest integer. Temperature output is converted to 8-bit values using the base_temp and the temp_step parameters.
Answer no if the output dataset is to be written as 16-bit integer data. Both radiance percent albedo and temperature degrees are converted to 16-bit values by multiplying by 100 and rounding to the nearest integer.
Valid responses are [yes or no]. The default is no.
If calibrate=yes and byte_output=yes, these two parameters are used to convert temperature output to 8-bit values as follows:
8-bit value = nearest int( ( temp - base)/step )temp_step must be in the range [.1, 2.]. There are no restrictions on base_temp. The default values for base_temp and temp_step depend on temp_units. For Kelvin or Celsius, the default temp_step is .5. For Fahrenheit, the default temp_step is 1. The default values for temp_base are -80, 193, and -120 for Celsius, Kelvin, and Fahrenheit respectively.
If calibrate=yes, answer no if only the calibration report for the first 100 lines is printed. Answer yes if a calibration report is printed for every 100 lines of input data.
Valid responses are [yes or no]. The default is no.
Answer yes if the dataset is to be geometrically corrected to compensate for the curvature of the earth. Because the MVISR sensor scans at a constant rate, pixels near the ends of scan lines are up to 5 times wider than pixels at the center of scan lines. This option redistributes the pixels along each scan line so each pixel is approximately square, about 1.1 km on a side. This involves replicating pixels near the ends of a given scan line, while discarding a few pixels at the center of the scan line.
Geometrically correcting full 2048-sample MVISR scan lines results in output lines containing 2560 samples.
Valid responses are [yes or no]. The default is no.
This parameter specifies the rate of subsampling in the direction of subtrack. If delta_line=3 every third line will be used. If delta_line=1, all lines will be used.
Valid responses are [1 through 8]. The default is 1.
This parameter specifies the rate of subsampling in the scan direction. If delta_sample=3 every third sample will be used. If delta_sample=1, all samples will be used.
Valid responses are [1 through 8]. The default is 1.
OPTIONAL. Indicates that only MVISR data corresponding to MVISR lines that intersect a user-specified latitude range will be ingested.
Minimum and maximum latitudes, used only when use_lat_range=yes. If min_lat is greater than max_lat, they are interchanged invisible to the user.
Latitudes must be specified in standard format, e.g., 34.5 n, 34 30 n, or 34 30 00 n. See formats. There is not default for either parameter.
Used only if use_lat_range=no. Answer yes if the data is to be selected from the intersection of a master dataset (see master). Answer no if subsets are to be specified by start_time and start_sample.
Valid responses are [yes, no]. The default is yes.
If use_master=yes, this is the name of the master dataset used to specify a region for 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 and use_lat_range=no, this is the start time for data extraction. The first line with a time greater than start_time is the first output line. A response of 00:00:00 instructs chrptin 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 use_lat_range=no this is the number of lines written to the output MVISR dataset. delta_line * num_lines input lines will be processed to produce an output dataset containing num_lines. 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 6000/delta_line.
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 2048]. The default is 1.
This parameter controls the number of samples written to the output dataset. If geo_correct=no, num_samples is the exact number of samples per line in the output dataset. If geo_correct=yes, then delta_sample * num_samples input samples will be processed to produce geometrically corrected lines that are then subsampled according to the delta_sample parameter.
The valid range is determined by [start_sample -1 + num_samples * delta_sample <= 2048]. The default is 1 + (2048 - start_sample)/delta_sample.
OPTIONAL. If ingest coincides with pass reception (e.g., the input pass is live), this parameter enables or disables reading directly from shared memory. It may be wise not to read from shared memory if writing output data is so slow that input telemetry is cycled out of shared memory before it can be read.
Valid responses are [yes, no]. The default is yes.
OPTIONAL. Determines whether or not a progress variable called dim_counts is written to the output datasets. A progress variable has an entry for each of the ten MVISR channels; the entries are updated to reflect the number of lines written for each channel. This parameter is intended for use by scrolling applications.
Valid responses are [yes, no]. The default is no.
Create a TeraScan dataset named dataset1 from a pass archived on tape. The area for data selection is specified by a master dataset.
[1] % chrptin dataset1 on_pass_disk : char( 3) ? [yes] n tape_device : char(255) ? [/dev/nwd0] pass_number : int ( 2) ? [1] files_per_pass : int ? [2] satellite : char( 11) ? [fy1-c] pass_date : char( 15) ? [2000/02/01] channels : int ( 10) ? [1 2 3 4 5 6 7 8 9 10] fix_missing : char( 3) ? [yes] n calibrate : char( 3) ? [yes] n geo_correct : char( 3) ? [no] delta_line : int ? [1] delta_sample : int ? [1] use_master : char( 3) ? [yes] master_file : char(255) ? [Master] Processing pass # 1. /dev/nwd0: fy1-c 2000/02/01 17:30:26.087 dataset1: Creating ... dataset1: Actual size is 944 lines by 511 samples.
Last Update: $Date: 2002/04/22 20:28:28 $