[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

981222: NOAAport sequence number (fwd)


===============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
address@hidden             WWW: http://www.unidata.ucar.edu/
===============================================================================

---------- Forwarded message ----------
Date: Thu, 27 May 1999 13:59:39 -0600
From: Steve Chiswell <address@hidden>
To: address@hidden, address@hidden,
    Chad Johnson <address@hidden>
Subject: 981222: NOAAport sequence number (fwd)


Robb, Chad and Mike,

Here is the message I sent in december about obtaining the sequence number
from the octet group in the NOAAport so that all downlink sites could
obtain the same sequence number.

Chiz

---------- Forwarded message ----------
Date: Tue, 22 Dec 1998 12:34:12 -0700
From: Steve Chiswell <address@hidden>
To: Chad Johnson <address@hidden>, Robb Kambic <address@hidden>
     address@hidden
Subject: 981222: NOAAport sequence number

Chad and Robb,

The NOAAport data stream does have a sequence number according to
the "NOAAPORT Broadcast System Document".

In the Product definition header section, there is a 4 octet group
at the end of the header called "Product Sequence Number".

By using the sequence number as included in the NOAAport data stream,
a common sequence number would exist for all sites ingesting the data,
and therefore not relying on each ingestor to generate its own
counter.

Since the number is 4 octets, the number could be mod 1000 to maintain
a 3 digit decimal LDM sequence number.

Glenn is planning to address the MD5 signature for data vs. data+header
for detecting the same data regardless of input source.

Steve Chiswell
Unidata User Support

On Tue, 22 Dec 1998, Robb Kambic wrote:

> 
> There is a field in the NOAAport header that contains date information, I
> believe it's 8 octals long that can be used to create the sequence number.
> If this field is used then all products from different ingesters would
> have the same sequence number. Steve Chiswell has the details about the
> field. I'm  working from home today and I don't have access to the
> information.
>