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[McIDAS #VSV-153140]: Mcidas xcd

Hi Heather,

> You don't have to add Vince onto these emails anymore,
> I originally cc'd him to help with the VPN.

OK, I just removed him from the CC list (which is now empty).

> About the Signal Strength:  the -100 dBm value has been around
> for awhile.  It was the same value from when the receiver was
> hooked up to our old ingestor.  But the carrier to noise value
> was 13.9dB.  ( I saved ALL the values from the old ingestor!)

OK, but this is weird and unexpected.  If it were up to me, I would
upgrade the S300 firmware to the latest release, V2R11, to see if
that made a difference.  Before you launch off to do this, however,
you should be aware that installing the new firmware will result
in the IP address of the Novra changing to  This
may or may not necessitate you changing some networking setups
(e.g., default route for UDP packets in /etc/sysconfig/static-routes,
etc.).  FYI: we are running the latest firmware, but we know that
V2R7 (the version you are running) seems to work OK.

Regarding your C/N: our C/N for the old broadcast (the one that
you are currently listening to but will need to change before
the end of the month) varies from about 15.2 to 16 dB and 14.2
to 15.1 dB for the new, expanded NOAAPort broadcast.  Since we
are experiencing unacceptable numbers of 'Gaps' in our ingest, we
are having our system serviced on Friday morning.  From the chatter
we have seen on the various email lists concerned with NOAAPort
ingest, we have been led to believe that our C/N for the new
broadcast is marginal, thus the scheduled system work on Friday.

> About the errors, is this the table you are referencing:
> http://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_table4-2.shtml

Yes and no. The problem is that there are still a number of GRIB2
messages in NOAAPort that are created from GRIB1 messages by a
program that is run (somewhere) in NOAA.  The problem is that
the conversion routine uses its own GRIB2 tables, and we have seen
that a number of the entries have been incorrect in the past and
some continue to be incorrect now.  Our NOAAPort ingest code uses
GEMPAK GRIB tables to interpret GRIB parameters so that useful
LDM/IDD Product IDs can be created thus allowing end-users to
create regular expressions that match desired subsets of feeds
that originate from NOAAPort (e.g., HDS, NGRID).  Even if there
is no GRIB table entry for a product, the product is still sent
along in the IDD datastream.  Packages like McIDAS-XCD which does
not pay any attention to the LDM/IDD Product IDs experience no
effects whatsoever from a missing Product ID.  Packages like
GEMPAK, on the other hand, do since users configure decoder actions
using regular expressions to match on specific products/sets of
products.  The bottom line is that experiencing [GB -1] errors
may safely be ignored ** depending on what your GRIB2 use actully
is **.

> Where should I go to modify values?

If you get into the mode of updating the GRIB tables used with
our NOAAPort ingest package (which live in the ~ldm/etc directory),
you will be on a slippery slope indeed.  I suggest that you not
take on this unsavory activity and simply use what we or very
active community members come up with.

> Thanks!!

No worries.

As I close this email I can say that McIDAS-XCD decoding is occurring
on your new decoding machine.  I shutdown 'vpnc' so that I could
get this reply off and shutdown so I can head into work.  Please take
a look at things to see if you see anything amiss and then let me know.


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Ticket Details
Ticket ID: VSV-153140
Department: Support McIDAS
Priority: Normal
Status: Closed

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