For more information on the Meteosat data decryption and MKU functionality see Meteosat High Resolution Image Dissemination Encryption Infrastructure. User Guide, EUMETSAT, EUM TD 02(R), Vol. 1.
Last Update: $Date: 1998/09/01 18:18:45 $
metin [ parameter=value ... ] [ outputfile ... ] metin [ parameter=value ... ] [ directory ]
Parameters are: on_pass_disk, pass_number, tape_device, delta_line, delta_sample, use_master, master_file, start_spin, num_spins, start_percent, width_percent, channels, calibrate, sublat, sublon, noblck, block_size, shared_mem, pipe_output, xvis, admin, fix_missing, saved_decrypt.
metin creates TeraScan CDF datasets from raw Meteosat VISSR telemetry data. The dataset may contain up to four images from IR, VISs, VISn and WV sensors. Conversion of IR and WV data to radiance is performed automatically using the conversion equation:
Radiance = (count - SPC) * CAL
Enter this where the conversion coefficients for IR ( IRSPC and CALIR) and WV (WVSPC and CALWV) channels are extracted from the telemetry if they were found there. Otherwise, the user will be informed that no conversion to radiance was done.
The IR and WV radiance data can be converted into the brightness temperature using IR and WV Temperature/Radiance Conversion tables for each Meteosat satellite.
The raw data can be read from the pass disk, UNIX disk or from tape. Raw data on tape must be in TeraScan Archive Format (TAF).
Meteosat is a weather satellite in an Earth-fixed orbit over the equator which (re)transmits environmental data.
Meteosat takes images in three spectral bands: The water vapor infrared (5.7-7.1 um) and thermal infrared (10.5-12.5 um) images are composed of 2500 lines x 2500 pixels (can be subsampled to 1250 x 1250), while the visible (0.5-0.9 um) image is composed of 5000 lines x 5000 pixels (can be subsampled to 2500 x 2500). The corresponding spatial resolution at the sub-satellite point is 5km (10 km) and 2.5 km (5.0 km) respectively. Scanning of the Earth nominally takes place every half-an-hour, providing images in all three spectral channels. Data from all spectral channels are coded in eight bits corresponding to 256 grey levels.
The overall spatial subset of 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 a specified size, determined by the start line and sample numbers, number of lines and samples and two parameters determining the subsampling rate.
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 dataset name. If a directory name is entered, output name will be generated and the file will reside in the specified directory. Name will look like m#.yyddd.hhmm, where # is the Meteosat satellite number, yyddd is the year and julian date, and hhmm is the time.
Meteosat data is usually encrypted; only the image data is affected, which means the data can be framed (captured) without decryption. metin actually performs the decryption of the image data. To do this, metin requires either:
Serial port access to a EUMETSAT Meteosat Key Unit (MKU), or
Decryption information saved into the first frame by mkuload.
In the first case, the MKU serial port is defined by the environment variable MKU_DEVICE. See mkuload for information on how it works with the MKU.
Satellite id's from input telemetry are converted to (satellite-name, subpoint-latitude, subpoint-longitude) using the table $SATDATA/pdus_satid. If this table is not present or readable, hard-coded conversions are used.
Answer yes if the passes are on disk and no if the passes are on tape.
Valid responses are [yes, no]. The default is no.
If on_pass_disk=y or tape_device specifies tape, pass_number is prompted. This is the number of each pas on the pass disk or on the tape to process. You can list passes on disk with the command lspass.
The range of valid responses depends on the pass disk or tape configuration. The default is the most recent pass (for pass disk) or 1 (for tape).
If on_pass_disk=no, metin prompts for tape_device. This takes the device address of the input tape device or UNIX file. Tape device names are machine specific.
This must be a valid UNIX tape device address or file name.
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_spin, start_percent, num_spins and width_percent.
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 an Earth transform. The default is Master.
If use_master=no, this is the spin number to start saving data.
Valid responses are [1..2500]. The default is 1. For B format the actual start_spin will be (1809 + start_spin) since the data starts from spin number 1810.
If use_master=no, this is the number of spins to retrieve.
Valid responses are [1..2500]. The default is 2500-start_spin+1.
If use_master=no, this defines the sample number to start saving data by specifying its ratio to the total number of samples in one scan.
Valid responses are [1..100]. The default is 0.
If use_master=no, this defines the number of samples to retrieve by specifying its ratio to the total number of samples in one scan.
Valid responses are [1..100]. The default is 100-start_percent.
Spins subsampling rate.
Valid responses are [1..4]. The default is 1.
Samples subsampling rate.
Valid responses are [1..4]. The default is 1.
Channels to extract from the input dataset.
Valid responses are [vis_n vis_s ir wv]. The default is to extract all channels. Entering the same channel more than once is not allowed.
Answer yes if the IR and WV data is to be converted from radiance to brightness temperature.
Valid responses are [yes, no]. The default is yes.
Longitude of the satellite's nominal subpoint.
Valid responses are [-180.0..+180.0]. The default is 0.0. This value is only used if $SATDATA/pdus_satid cannot be read.
OPTIONAL. Latitude of the satellite's nominal subpoint.
Valid responses are [-90.0..+90.0]. The default is 0.0. There is no known reason why one may want to make this value non-zero. This value is only used if $SATDATA/pdus_satid cannot be read.
OPTIONAL. This parameter says whether the Meteosat frames were written sequentially with no gaps (yes) or by physical blocks with the size a multiple of 512 (no).
Valid responses are yes and no. The default answer no should be used for the data captured by TeraScan system. The answer yes is offered to read the format used by some of the customers.
OPTIONAL. Used only if noblck=no. Specifies the physical record size in bytes. The valid range is [>64*364]. The default is 23552. Note that each physical record is assumed to contain exactly 64 logical records, each containing 364 bytes.
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 (e.g., when the output dataset is remote or when using pipe_output=yes). Valid responses are [yes, no]. The default is yes.
OPTIONAL. If UNIX stdout is not a terminal, this parameter enables writing of image data to stdout in addition to the normal output dataset. Piped data is serialized, and is generally used in conjunction with deflate and inflate functions. Valid responses are [yes, no]. The default is no.
OPTIONAL. This parameter, if non-zero, will force IR channel in X format to be interpreted as either VIS_s (xvis=1) or VIS_n (xvis=2).
Valid responses are 0,1,2. The default answer 0 should always be used except for the case of visible data in X format.
OPTIONAL. This parameter controls whether or not to print administrative message.
Valid responses are [yes, no]. The default response is no.
OPTIONAL. This parameter controls whether or not gaps of one or two missing lines are automatically fixed.
Valid responses are [yes, no]. The default response is no.
The fix rule is as follows; here 'b' means missing data, and numbers mean good data:
input output comment
1 1 1 1 1 1 1 1 1 1
b b b b b 1 1 1 1 1 previous line replicated
b b b b b b b b b b no good neighbors - still missed
b b b b b 2 2 2 2 2 next line replicated
2 2 2 2 2 2 2 2 2 2
OPTIONAL. This parameter indicates whether or not to ignore decryption information saved into the first Meteosat frame by mkuload. Normally, saved_decrypt=yes, and the first frame is checked for decryption information; if it is not there, and the data contains encrypted image data, then an attempt will be made to access the MKU. If saved_decrypt=no, then no attempt is made to find decryption information in the first frame. This later case is useful ONLY when the decryption info saved in the first frame by mkuload is wrong, e.g., based on old keys.
Valid responses are [yes, no]. The default response is yes.
The following example creates a file containing a full-Earth disk with all available channels.
[1] % metin output file(s) : char(255) ? [.] on_pass_disk : char( 3) ? [yes] pass_number : int (100) ? [1] delta_line : int ? [1] delta_sample : int ? [1] use_master : char( 3) ? [yes] n start_spin : int ? [1] num_spins : int ? [2500] start_percent : real ? [1] width_percent : real ? [100] channels : char( 19) ? vis_n ir vis_s wv sublon : real ? [0.0] calibrate : char( 3) ? [yes] writing file m3.93132.0708 pass number 1: vis_n found pass number 1: ir found
metcal, datasets, etx, master, xcapcon.
For more detailed documentation on the Meteosat satellite, telemetries and the VISSR sensor, see Meteosat High Resolution Image Dissemination, Meteosat Exploitation Project, European Space Operations Center, Federal Republic of Germany, October 1989.
For more information on the Meteosat data decryption and MKU functionality see Meteosat High Resolution Image Dissemination Encryption Infrastructure. User Guide, EUMETSAT, EUM TD 02(R), Vol. 1.
Last Update: $Date: 1998/09/01 18:18:45 $