The ELF data file format description

  • Every file contains 5 minutes of ELF data
  • The name of a file is a time of data sample beginning
  • Every sample has 16 bit length (the older byte + the younger byte)
  • Every 5 minutes file begins with a 64 byte ASCII header

An example of 5 minutes file header (the first 64 bytes in ASCII):

Stacja ELF ELA7b02.07.2008 11:401 3 T: 30.3000000000000000000000

  • Stacja ELF ELA7b - the name of a measuring station
  • 02.07.2008 11:40 - time (UT) of the data sample beginning
  • 1 3 - names and numbers of sampled canals (canal1=NS and canal3=EW)
  • T: 30.3 - temperature of a station in Celsius degree

Immediately after the end of the 64 byte ASCII header start sampled data:

After 300 seconds of sampling the file is closed and the remaining part of the last sector of a file must be filled with zeros (0x00), because the next 5 minutes file will start at the next 512 bytes sector on data storage disc.

This is an example of a termination of the 5 minutes ELF file (last 512 bytes sector):

The last two bytes 0xCE33 = 52787 this is a counter of samples during 300 seconds. It means, a frequency of sampling is 52787 / 300 = 175.95 sample/sec simultaneously in both canals.