Guralp Systems CMG-DM24 - Manual (Page 106)

CMG-DM24
The field is a signed 31-bit positive integer, allowing System IDs up to
ZIK0ZJ.
If the top bit of this field is set, the bottom 26 bits of this field specify a
label of up to 5 characters using the same encoding. In this case, the
field is a signed 26-bit positive integer, allowing System IDs up to
ZZZZZ. Bits 26 – 30 of the System ID field are reserved in this case.
Stream ID : a unique 6-character label identifying the device,
component and sample rate:
1 2 3 4 5 6
Device serial number Component Output tap
The 6-character label is encoded in 4 bytes as a base 36 number, in the
same manner as the System ID, above.
Date code : The date and time when the data in the block begins,
expressed as a 32-bit number where
•
the bottom 17 bits are the time in seconds since midnight,
normally between 0 and 86399 but possibly 86400 or 86401 in
years with 'leap seconds'; and
•
the top 15 bits are the Güralp day number, with day zero on 17
November 1989. The day number increments when the seconds
number rolls over at midnight.
Data format : The final header element contains 4 bytes defining the
format of the data in the block:
1 2 3 4
reserved Sample rate Compression code Number of data
records
Sample rate : The sample rate of the data records, an integer number of
samples per second. If this field is zero, the block body contains status
information in ASCII text format.
Compression code : A code for the compression format used for all the
data in the block. Currently accepted values are
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