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[IDD #WHP-619598]: NLDN access

Hi Lee,

> I can't find anywhere on the Unidata website the binary format
> specifications for the FT14 feedtype.  Do you know where those might
> be?  I contacted David Knight at SUNY Albany, but he does not have
> that information, and recommended I talk to you.

Here is a description of the binary NLDN records received contained in
the IDD NLDN datafeed with sizes and a short description of the various

** NLDN record:
** size    value     description
** -------+---------+----------------------------------------------------
** char[4] NLDN      'NLDN' marks the start of record
** int     tsec      time in seconds since 1970
** int     nsec      nanoseconds since tsec (seems to be thousandths)
** int     lat       latitude [deg] * 1000
** int     lon       longitude [deg] * 1000
** short   fill      padding
** short   sgnl      signal strength * 10 [150 NLDN measures ~= 30 kAmps]
** short   fill      padding
** short   mult      multiplicity [#strokes per flash]
** char    fill      padding
** char    semimaj   semi-major axis
** char    eccent    eccentricity
** char    angle     ellipse angle
** char    chisqr    chi-square

> The website you linked to suggests that there is a way to immediately
> convert the feed to netCDF via a decoder?

The comment made in http://www.unidata.ucar.edu/data/lightning.html:

 "When a lightning data packet is received by an LDM server, a decoder may
  be automatically invoked to convert the NLDN-native format to, for example,
  a Unidata netCDF file. Unidata and SUNY have established an IDD feedtype,
  NLDN FT 14, for this data stream."

was meant to be illustrative.  We do not currently provide a decoder that
converts the NLDN broadcast format into netCDF.

> That would probably be
> easiest, but just getting the binary format specification for the
> native NLDN feedtype would be fine, too.

Please see above.

> Thanks so much,

No worries.


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Ticket Details
Ticket ID: WHP-619598
Department: Support IDD
Priority: Normal
Status: Closed