Hi Takeshi, re: > I need help to interpret NLDN binary data. > > We are receiving NLDN data feed at GI/UAF and storing it as the > original binary format. I am trying to convert these binary to ascii > format. > > I referred to your website > (http://www.unidata.ucar.edu/data/lightning.html) and LDM-MCIDAS > decorder source code. What I've found it works better is; > > char[4] NLDN 'NLDN' marks the start of record > int[4] tsec time in seconds since 1970 > int[4] nsec nanoseconds since tsec (seems to be thousandths) > int[4] lat latitude [deg] * 1000 > int[4] lon longitude [deg] * 1000 > short[2] fill padding > short[2] sgnl signal strength * 10 [150 NLDN measures ~= 30 kAmps] > short[2] fill padding > char[1] mult multiplicity [#strokes per flash] > char[1] fill padding > char[1] semimaj semi-major axis > char[1] eccent eccentricity > char[1] angle ellipse angle > char[1] chisqr chi-square > > However, reading the binary with this description gives me "nsec" like > 100000000, 300000000..., i.e. single leading digit followed by eight > zeros. > The NLDN data is supposed to have millisecond resolution. I am > confused how to interpret it. The original documentation we received (many years ago) on the NLDN data said that 'tsec' was nanoseconds (1.E-9 s, as per list above). As you say, the values seem too large for there to be millisecond resolution unless one views 100 ms, 300 ms as 'millisecond resolution'. > Could you tell me how to interpret the NLDN binary file? I have always interpreted the numbers as nanoseconds so that the numbers you report indicate tenths of a second resolution, not milliseconds as the original documentation we were provided indicates. We were never concerned with this since our decoding of the NLDN data into McIDAS and GEMPAK formats assigned times with 1 second resolution (the reason why the ldm-mcidas source code, nldninput.c, does nothing with time_tsec). Cheers, Tom **************************************************************************** Unidata User Support UCAR Unidata Program (303) 497-8642 P.O. Box 3000 address@hidden Boulder, CO 80307 ---------------------------------------------------------------------------- Unidata HomePage http://www.unidata.ucar.edu **************************************************************************** Ticket Details =================== Ticket ID: KWB-817118 Department: Support ldm-mcidas Priority: Normal Status: Closed
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