User's Guide

TAPEL1B

Copy Level 1b file(s) on disk to ANSI labeled tape

Function:

Copy Level 1b file(s) on disk to tape for AVHRR image(s). Associated data are written, including the terabit memory (TBM) header or, for NOAA KLM series satellites, the Archive Retrieval System (ARS) header, the data set (DSH) header, dropped line information, telemetry data, sun zenith angles, earth location data, and calibration coefficients. This program can be used to create tapes for HRPT, LAC, and GAC images. Windowing is not allowed in this routine.

Parameters:

INFILE
Name of input Level 1b file on disk.

COMMENT
Description of ANSI labeled tape. A text string sent to the operator's terminal describing the tape to mount. If a new tape is being created, the comment should indicate the type of tape to be used. For example, "please mount a 8MM ANSI labeled tape." If there is a specific tape the images are to be placed on, then the comment should contain the tape library identification number and a short description of the tape. This will allow the operator to ensure that the correct tape is mounted. If more than one tape will be required, the same comment will be used to request another tape when the first is full. If COMMENT is defaulted, INFILE must be specified.

TTYPE(&$TTYPE)
Tape type. Type of tape that is to be stacked. The default is defined by the TAE global $TTYPE. The list of valid tape types is defined by the TAE global $TTYPEVAL.

TAPEDENS(&$TPDENS)
Tape density. The density of the tape in bytes per inch. The default is defined by the TAE global $TPDENS. The list of valid densities are defined by the TAE global $TPVAL.

MAXBYTES(--)
Maximum megabytes. The maximum number of megabytes that can be written to a tape.

MVOLFLG(YES)
Multi-volume flag. Indicates whether more than one tape may be used for the order. The available options are:

  = YES: Multiple tapes may be used for this tape set.

  = NO:  Only one tape will be used.  If logical tape end
	 is reached, processing stops and remaining part
	 of image is not written to tape.

Note: single images will not be split across multiple tapes.

SUMFLG(NO)
Summary flag. Determines whether or not a product summary is printed for each individual scene that is written.

ACCTNUM(--)
Account number. The account number to which this order will be sent and billed.

ORDERNUM(--)
Order number. The order number that includes this item.

UNITNUM(--)
Unit number. The Level 1b unit number of the specified order.

ADDRESS(--)
Shipping address. This address will be printed on the tape label and the shipping form.

PRODESC(LEVEL1B)
Product description. A description of the Level 1b product which will appear on the Product Summary. If there is a special description for the product, it should be placed in PRODESC.

Examples:

  1. LAS> tapel1b infile=(al14070297131200, al14070297131438) comment="please mount a 8mm ansi labeled tape" ttype=8hi mvolflg=no acctnum="123456789" ordernum="91121800004" unitnum=3 address=("address line 1","address line 2", "address line 3")

    The two images will be written to 8MM tape. All channels present, all lines and samples will be written. Multiple volumes are not allowed. This tape is being created for account number 123456789, unit three, of order 9112180004. Default PRODESC is "LEVEL1B", and the default tape density will be used. Product summary information will not be printed. The order will be sent to the address specified.

Description/Algorithm:

An ANSI labeled tape is mounted. The specified AVHRR Level 1b file is opened for reading. The 122-byte terabit memory (TBM) or 512-byte Archive Retrieval System (ARS) header is written to the output tape. The data set header (DSH), with a length of that of the image data records, is written to the output tape. For non-KLM LAC and HRPT data, an extra dummy header record the same length as the image data record is written to create a set of two records in a format similar to the LAC/HRPT image data records (see below). KLM and GAC data does not require this dummy header because their image data records are not in sets of two.

Next, the actual image data are written. One line of image data includes the line number, time stamp code, calibration coefficients, zenith angles, earth location data, telemetry data, and the actual pixel values. The length of a line of image data depends on the data type, number of channels, and whether or not the data is packed. For non-KLM GAC data, two lines of the image are written into physical one record; for non-KLM LAC and HRPT data, one line of the image is written into two physical records. All KLM data sets contain one line of data per logical record. If less than five channels are present, the image data are written in an unpacked format as one ten-bit pixel value in one 16-bit word. If five channels are present, the data will be written in unpacked format, or will have three ten-bit pixels packed into one 32-bit word (the format of the input image will reflect that of the input image). If the logical end of the tape is encountered during writing, another tape will be requested if MVOLFLG is YES. Processing will stop if MVOLFLG is NO.

After all the desired lines have been written, the input and output files are closed. A label for each tape is created and a Level 1b product summary is generated.

Nonfatal Error Messages:

  1. [tapel1b-imgcler] Error closing Level 1b image

    An error occurred trying to close the Level 1b image file. Check with system administrator if problem persists.

  2. [tapel1b-vbupder] Error updating variable block

    The TAE variable block was not updated properly. Check with system administrator if problem persists.

  3. [tapel1b-ltend] Logical tape end reached

    The logical tape end, parameter MAXBYTES, was reached before writing the entire image. If MVOLFLG is YES another tape will be mounted and the full scene will be written to the new tape. If MVOLFLG is NO processing stops. The partial image is left on the first tape (see user note 4).

Fatal Error Messages:

  1. [tapel1b-fatal] Fatal error encountered

    A fatal error was encountered during processing. The error message displayed immediately preceding this message is the specific error encountered.

  2. [tapel1b-maxb] MAXBYTES greater than allowed

    The specified MAXBYTES was greater than the physical tape type will allow. Specify a smaller MAXBYTES value and retry.

  3. [tapel1b-parm] Required parameter not specified: <XXXXX>

    The operator must specify a value for <XXXXXX>. Specify a value for <XXXXX> and retry.

  4. [tapel1b-ttype] Invalid tape type specified

    An invalid tape type was specified. Retry specifying a valid tape type.

  5. [tapel1b-iread] Error reading image line

    An error occurred reading the input image. Verify that the contents of this file is correct.

  6. [tapel1b-bdimagwr] Error writing image line

    An error occurred writing to the output image. Verify that the proper file permissions exist.

User Notes:

  1. When the MVOLFLG is set to YES and all files will not fit on a single tape, partial files may be present at the end of all but the last tape in the set. This is due to peculiarities in certain tape drives that do not allow proper back spacing. To skirt this problem, when logical tape end is reached the drive is simple closed and the current file is put on the next tape in the set.

  2. A Level 1b tape or file is created in response to a customer order for AVHRR data. The customer's account number, the order number, and the unit number of that order are recorded on the Product Summary and tape labels.

  3. For more information about the Level 1b format, refer to the NOAA Polar Orbital User's Guide.

  4. To ensure that tapes generated by TAPEL1B can be uniquely identified, only ANSI labeled tapes may be used (even though the resultant Level 1b tape format is not an ANSI standard tape).