The following is an excerpt from the
ICD for the Archive II Userdocument.
To exploit the Archive II data the end user must develop a program to extract and decompress the bz2 data stored in the LDM raw data file. Once decompressed each message requires 2432 bytes of storage with the exception of Message Type 31 (Digital Radar Data Generic Format) which is variable length.
The first record in the file is the Volume Header Record, a 24-byte record. This record will contain the volume number along with a date and time field.
This second record is bzip2 compressed. It consists of Metadata message types 15, 13, 18, 3, 5, and 2. See section 7.3.5. This is all related to radar site status.
The first LDM Compressed Record contains the Archive II messages comprising the Archive II metadata.
The size of the uncompressed metadata is fixed at 134 messages, ie. 325888 bytes.
The following table contains the message types in the sequence in which they are placed in the LDM Compressed Record.
It contains the number of 2432 byte message segments set aside for each message type when they are uncompressed.
In those instances where the message requires fewer segments than indicated the message type field of the excess message segments will be set to zero.
Starting with Build 19, Message type 13 will not be included in the Metadata Record. The space reserved for this message will be filled with zeros.
A variable size record that is bzip2 compressed. It consists of 120 radial data messages (type 1 or 31) plus 0 or more RDA Status messages (type 2).
The last message will have a radial status signaling “end of elevation” or “end of volume”. See paragraph 7.3.4. Repeat (LDM Compressed Record) Or End of File (for end of volume data)
| Message Type | Description |
|---|---|
| Message 2 | RDA Status Data, contains the state of operational functions |
| Message 3 | RDA Performance/Maintenance Data |
| Message 5 | RDA Volume Coverage Pattern |
| Message 13 | RDA Clutter Filter Bypass Map |
| Message 15 | RDA Clutter Map Data |
| Message 18 | RDA Adaptation Data |
| Message 31 | Digital Radar Data Generic Format |
- List of ICDs (Interface Control Documents) - Consider these the documentation specs for how data is transported and processed from the Radar unit into radar products.
- ICD for RDA/RPG - The spec on the file format and field values on the archive 2 data format.
- INTERFACE CONTROL DOCUMENT FOR THE ARCHIVE II/USER - This document describes how the radar unit transfers data to the RPG (radar product generator - the thing that makes radar images). It also contains a high level overview of the Archive2 data format.