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20040921: IDV - IDV and our Level II feed

>From: "Robert Trapp" <address@hidden>
>Organization: Purdue
>Keywords: 200409212158.i8LLw7QV007550 IDV level II radar

Hi Jeff-

>Institution: Purdue University
>Package Version: 1.1
>Operating System: Linux/Redhat
>Hardware Information: Dell PC running Linux
>Inquiry: Greetings.
>
>We're exploring our different options for displaying live Level II data (no pr
> oblems with the archived data).  I've read the release notes on the capabilit
> y to do this, but still not sure how/where to direct IDV.
>
>The config file generates "archived" data in, for example, L2-BZIP2/KICT/20040
> 921185447/252
>which contains a series of files like 1, 10, 11, ...

It looks like you are filing each of the 100 radial packets in individual
files instead of collecting them all together to create one volume file.
On the nexrad feed, a volume is broken into 100 radial chunks.  You need
to collect them all in one file for either IDV or GEMPAK (or any other
level II reader I would guess) to read them.

>On a few occasions, IDV will accept one of these files, but mostly doesn't rec
> ognize them.

Only the first file would be recognized because that contains the 
necessary header information.

>Am I close here?  I realize that the config file can also use the GEMPAK decod
> er and generate something that GEMPAK and recognize.   

You don't need to run the decoder, just file all the radial bundles
in one file.  Here's the pqact.conf entry we use:

# CRAFT stored as raw bz2 for GEMPAK and IDV
#
# file the raw data to a temporary file beginning with "." so that autoupdate 
# GUIs don't get ugly partial volume plots
CRAFT   
^L2-BZIP2/(....)/([0-9][0-9][0-9][0-9][0-1][0-9][0-3][0-9])([0-2][0-9][0-5][0-9])([0-9][0-9])
        FILE    data/gempak/nexrad/craft/\1/.\1_\2_\3
#
# Done to move file after last record is received "/E" to prevent
# autoupdate from seeing partially received files (dccraft_move is a shell scrip
t copied from $NAWIPS/bin/scripts)
CRAFT   
^L2-BZIP2/(....)/([0-9][0-9][0-9][0-9][0-1][0-9][0-3][0-9])([0-2][0-9][0-5][0-9])([0-9][0-9]).*/E$
        EXEC    util/dccraft_move data/gempak/nexrad/craft/\1/.\1_\2_\3 
data/gempak/nexrad/craft/\1/\1_\2_\3


(you could use NEXRAD2 for the feed type if you are using the latest
LDM)

and the dccraft_move script is:

#!/bin/csh -f
#
# Shell script to move a file in the data tree, with check
# to avoid overwriting data (in case of retransmission on data).

if ($#argv != 2 ) then
   echo "Usage: $0 tmpfile finalfile"
   exit 0
endif

if ( ! -e $1 ) then
   echo "could not find $1"
   exit 0
endif

if ( ! -e $2 ) then
   mv $1 $2
else 
   # don't overwrite outfile!
endif

exit 0


With this, the radials are output to a temporary file (filename prepended
with .) until they are all received and then they moved to the proper
filename.  You could just file them to the final name, but you might
get partial scans if you are looking at a file that is being populated.

Don Murray
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