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[Datastream #LBS-132460]: NEXRAD3 data rebroadcasts

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  • Subject: [Datastream #LBS-132460]: NEXRAD3 data rebroadcasts
  • Date: Fri, 23 Dec 2011 08:43:04 -0700
Hi Matt,

re:
> Is anyone else seeing a constant stream of rebroadcast Nids data
> today?

We didn't notice anything unusual, but, then again, we are not looking as
hard as you are.  The volume plot for input into the toplevel IDD relay
we operate here in UCAR, idd.unidata.ucar.edu, does not show anything 
remarkable:

http://www.unidata.ucar.edu/cgi-bin/rtstats/iddstats_vol_nc?NEXRAD3+idd.unidata.ucar.edu

Perhaps we are not "feeling" the rebroadcasts because our LDM queue sizes
are large enough to reject duplicate products that don't come in too long
after the original ones are received.

re:
> We are seeing products that are up to several days old:
> 
> Dec 22 23:05:16 pqutil INFO:    13563 20111222230515.826 NEXRAD3 438  SDUS21 
> KBTV 222137 /pN3UTYX
> Dec 22 23:05:16 pqutil INFO:     2299 20111222230515.826 NEXRAD3 440  SDUS34 
> KEWX 222035 /pN1PDFX
> Dec 22 23:05:16 pqutil INFO:     4013 20111222230515.827 NEXRAD3 441  SDUS34 
> KEWX 222035 /pN3SDFX
> Dec 22 23:05:16 pqutil INFO:     8974 20111222230515.836 NEXRAD3 990  SDUS53 
> KTOP 222038 /pNCRTWX
> Dec 22 23:05:16 pqutil INFO:     7760 20111222230515.837 NEXRAD3 991  SDUS26 
> KSGX 222040 /pN1QNKX
> Dec 22 23:05:16 pqutil INFO:    19229 20111222230515.850 NEXRAD3 454  SDUS57 
> PAJK 222300 /pNCRACG

I am not seeing an indication that the products included in this listing
are up to several days old.  In fact, the products all seem to have
been inserted into the originating LDM queue immediately before before
you produced this listing.  Example:

Listing time            Product Creation time
Dec 22 23:05:16         20111222230515.826 == Dec 22 23:05:15.826

The time indicated for this product is "old", but only by about an
hour and a half: 222137 == Dec 22 21:37.

The typical reasons for seeing "old" or repeat products in an IDD
datastream are:

- rebroadcast by the NWS

  This typically happens when a WFO ask for a resend of data.

- "recirculation" in the IDD

  In this case, one would see an old time of product creation.  Your
  listing does not show this.

re:
> Is there a good way to tell LDM to ignore these?

If your LDM queue is large enough so that the original product is
still in the queue when the repeat one is received, it will automatically
be rejected.

re:
> I tried a -m switch, but it does not seem to be doing any good.
> 
> Any help appreciated.

Please let us know if the above does not help you.

Cheers,

Tom
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Ticket Details
===================
Ticket ID: LBS-132460
Department: Support Datastream
Priority: Normal
Status: Closed