McIDAS-XCD Administrator's Guide
Version 2005

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Configuring the NEXRAD Decoder

If you will be decoding NEXRAD radar products you must configure the file NEXRID.CFG (which defines the stations and products that will be decoded by the NEXRFILE decoder, and the amount and location of data to store) and then activate the data monitor.

1. Edit the file ~oper/mcidas/data/NEXRID.CFG and set the values for the following variables:
   


• FILE=  and EXCEPT=  variables in the STATIONS control line
• FILE=  and EXCEPT=  variables in the PRODUCTS control line
• DIRFILE=  and KEEP=  variables in the DISPOSE control line


2. Activate the NEXRAD data monitor by running the following command in a McIDAS-X session running under the oper account.

Type: DECINFO SET DMNEXR ACTIVE

Note: The Unix warning message component of path does not exist will normally be displayed by the NEXRAD decoder each time it creates a subdirectory for incoming stations and products. The error message is normal, so can be ignored.

Creating a Separate Spool File for the NEXRAD Decoder (optional)

We have found that creating a separate spool file for the NEXRAD data significantly reduces processor usage. The gains in efficiency are due to the fact that the NEXRAD decoder no longer has to scan through GRIB data looking for the next NEXRAD product and similarly for the GRIB decoder. Note - We use the LDM to separate the NEXRAD data from the GRIB and BUFR data so if you do not use the LDM to receive data on your McIDAS-XCD machine then you will not be able to use this procedure. Implimentation of this procedure is entirely optional. The idea of separating out the NEXRAD data as well as the procedure below to impliment it come from the inspiration and pirspiration of Paul Wahner at the Cape Canaveral Forecast Facility, thanks Paul!

1. Stop the NEXRAD decoder, from a McIDAS text window type;

   DECINFO SET DMNEXR INACTIVE

2. Copy the NBIN circuit configuration file (no changes to the file need be made), from a shell window type;

   cp ~oper/mcdas/data/NBIN.CFG ~oper/mcidas/data/NEXR.CFG

3. Add the new NEXR circuit, from a McIDAS text window type;

   CIRCUIT ADD NEXR INGESTOR=INGEBIN CONFIG=NEXR.CFG SPOOL=NEXR.SPL "NOAAPORT NWSTG NEXRAD Binary Circuit

4. Modify the NEXRAD decoder configuration file with the name of the new circuit
   1. Open ~oper/mcidas/data/NEXRFILE.CFG for editing
   2. Change the value of SPLFILE= to NEXR.SPL
   3. Save and close the file


5. Modify the LDM configuration so that it pipes NEXRAD data to a second instance of the binary ingestor
   1. Open ~ldm/etc/pqact.conf for editing
   2. Create a separate entry in the 'Request Entries' section for NEXRAD data and set it to pipe the data to the binary ingestor using the NEXR circuit. If you had a line that contained NNEXRAD as well as other binary feeds such as HRS, remove NNEXRAD from this line. The resulting entry should look like this;

      Type: NNEXRAD ^.* PIPE /home/oper/mcidas/bin/ingebin.k NEXR

   3. Save and close the file


6. Remove the old pointer file for the NEXRAD decoder, from a shell window type;

   rm ~oper/mcidas/data/NEXRFILE.PRO

7. Stop and restart the LDM, from a shell window type;

   ldmadmin restart

8. Start the NEXRAD decoder, from a McIDAS text window, type;

   DECINFO SET DMNEXR ACTIVE

You should notice very soon after starting the NEXRAD decoder that there is a third entry in the ingestor section of the statdisp display. Two instances of the binary ingestor (ingebin) will exist. The NEXRAD data should now be written to NEXR.SPL by the binary ingestor using the NEXR circuit.

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