20010117: NIDS format docs?

>From: David Wojtowicz <address@hidden>
>Organization: UIUC
>Keywords: 200101171410.f0HEATe08773 NEXRAD format

David,

> I was wondering if you could point me to a reference
>to the actual file format for the NIDS products.  I'd like
>to be able to read the data directly from the files into
>a program.   I've looked around and come across many various
>other details of the data transmission scheme, etc, but not
>of the file format.  I understand it is non-trivial, but I'm
>willing to take a shot at it.
>  
> Thanks for any info!

Here is a snippit from my McIDAS ADDE server code that more-or-less
shows what the zlib-compressed NOAAPORT NEXRAD Level III product
format:

    /*
    ** Copy header bytes to decompression buffer.  The objective is to
    ** create an output buffer that looks like an uncompressed NOAAPORT
    ** NEXRAD product:
    **
    **   Section               Product               Example             End    
    **            +--------------------------------+
    **            |                                |
    **      1     |        start of product        | CTRL-A              \r\r\n
    **            |                                |
    **            +--------------------------------+
    **            |                                |
    **      2     |        sequence number         | 237                 \r\r\n
    **            |                                |
    **            +--------------------------------+
    **            |                                |
    **      3     |          WMO header            | SDUS53 KARX 062213  \r\r\n
    **            |                                |
    **            +--------------------------------+
    **            |                                |
    **      4     |             PIL                | N0RARX              \r\r\n
    **            |                                |
    **            +--------------------------------+
    **            |                                |
    **      5     |                                | AAO130006R2 CH-1
    **            |                                | Interface Control
    **            |             CCB                | Document (ICD)
    **            |                                | for the NWS NWSTG
    **            |                                | Figure 7-1 p 38
    **            |                                |
    **            +--------------------------------+
    **            |                                |
    **      6     |          WMO header            | SDUS53 KARX 062213  \r\r\n
    **            |                                |
    **            +--------------------------------+
    **            |                                |
    **      7     |             PIL                | N0RARX              \r\r\n
    **            |                                |
    **            +--------------------------------+
    **            |                                |
    **            |                                |
    **            |                                |
    **            |                                |
    **      8     |            image               |
    **            |                                |
    **            |                                |
    **            |                                |
    **            |                                |
    **            +--------------------------------+
    **            |                                |
    **      9     |            trailer             | \r\r\nETX
    **            |                                |
    **            +--------------------------------+
    **            |                                |
    **     10     |     Unidata floater trailer    | \0\0
    **            |                                |
    **            +--------------------------------+
    **
    ** Sections 5-8 are zlib compressed.  They must be uncompressed and
    ** read to find out where the image begins.  When this is done, sections
    ** 5-7 are thrown away and 8 is returned immediately following 4.
    ** Section 9 and, if it is there, section 10 are also thrown away.
    **
    */

Notice the reference to the document at the upper right of this listing.

AAO130006R2 CH-1 ...

This is the definitive reference that you are probably looking for.

The other thing you can do is extract my unzlib code and use it or
extract the equivalent code from GEMPAK.

Tom Yoksas