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20000906: September 15 Unidata-Wisconsin change



>From: Unidata Support <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200009071239.e87CdRN24598 ldm-mcidas pnga2area

Tom,

From the IDD operational status information we maintain,
I see that you are receiving the images from the Unidata-Wisconsin
(UW) datastream (MCIDAS feed type).  I verified this by doing
a 'notifyme' from our offices here in Boulder:

notifyme -vxl- -o 3600 -f MCIDAS -h kelvin.ca.uky.edu

I have been monitoring downloads of the latest ldm-mcidas distribution
(ldm-mcidas-7.6.4), and I have not seen you (your site) get the
new decoders.

I need to remind you that without upgrading your ldm-mcidas decoders,
you will no longer be able to decode images in the Unidata-Wisconsin
datastream after 18Z on Friday, September 15.  This is when the old
format files (delta encoded; decodable by the ldm-mcidas routine
'lwtoa3') will be removed from the datastream.  This change was
first announced at the end of June, and was reiterated in August
and just last week.

I see that the LDM on your IDD machine seems to be configured to
request only the old format image files from your upstream feed site.
This could be the result of one of two possibilities:

o your ~ldm/ldmd.conf file has a general request for the UNIDATA feed
  that has a regular expression for products that does not recognize
  that the header for PNG compressed images in the UW stream begins
  with a lower case letter.  Your pattern may look something like:

  request UNIDATA "(^[A-OQ-X])|(^[YZ].[^AHIJRU])" feed_site_hostname

o your ~ldm/ldmd.conf file has a general request for the MCIDAS feed
  that has a regular expression for products that does not recognize
  that the header for PNG compressed images in the UW stream begins
  with a lower case letter.  Your pattern may look something like:

  request WMO "(^[A-OQ-X])|(^[YZ].[^AHIJRU])" feed_site_hostname
  request MCIDAS "(^[A-OQ-X])|(^[YZ].[^AHIJRU])" feed_site_hostname


In both cases, the '^[A-OQ-X]' pattern would specify that only products with
headers whose first character is a capital letter (except for P in this case)
be requested from the upstream feed site.

If your ldmd.conf file does have a pattern similar to this, it could be
changed to:

request UNIDATA "(^[A-OpQ-X])|(^[YZ].[^AHIJRU])" feed_site_hostname

or:

request WMO "(^[A-OQ-X])|(^[YZ].[^AHIJRU])" feed_site_hostname
request MCIDAS "pnga2area Q." feed_site_hostname

(there are a great number of regular expression that would work; these are
two that come to mind first)


After you make the change in ldmd.conf and stop and restart your LDM, you
will start receiving the new, PNG compressed imagery.  At this point, you
will need to install the ldm-mcidas 'pnga2area' decoder to process them.

Information on how to setup this decoder in replacement of 'lwtoa3' can
be found in the LDM-McIDAS web pages that we maintain:

http://www.unidata.ucar.edu/packages/mcidas/mcidd
  
We are available if you need help in this transition.  Please don't hesitate
to ask if you run into any problems.

Tom Yoksas