State of Health File
The state of health file is a diagnostic information status stream produced by the seismometer. The state of health file contains a GPS status message every minute, an environmental measurements message every ten minutes, a GPS synchronization status message every twenty minutes and GPS timing, visibility and position message every hour.
GPS Status message:
o/s: The current offset between the internal clock vs GPS time.
Drift: The difference between current o/s and previous o/s.
Pwm (Pulse Width Modulation): Feedback control parameter.
Manual 3-D: Signifies that enough GPS satellites are visible to obtain a 3D fix. If “No Fix” is displayed, the GPS received has not yet been able to obtain a satisfactory fix.
Example: 2015 11 5 06:00:00 o/s= 2152 drift= 2036 pwm= 8649 Manual 3D
Environmental Measurements:
External Supply: Voltage received by seismometer from the power supply.
Temperature: Internal temperature of seismometer.
Example: 2015 11 5 06:05:00 External supply : 14.1V Temperature 12.62'C
GPS synchronization:
Current Offset: Current offset between internal clock from GPS time in micro seconds. Slow or fast is used to represent if internal clock is ahead or behind GPS time.
Frequency error: Frequency error in Hz.
Mass Position: Displays the current mass positions.
Example: 2015 11 5 06:30:00 29.2 MicroSec Slow Freq error -74 e-9
2015 11 5 06:30:00 Mass Positions 5% -1%-19%
GPS timing, visibility and position:
GPS timing: The current time provided by GPS
Satellite visibility: SV#’s, which stands for Space Vehicle Number is a list of all usable satellites. A minimum of four satellites is required to obtain a full 3-D GPS fix.
Seismometer position: Latitude, longitude and height of the seismometer. If position is unavailable, the latitude, longitude and height are shown as below.
Example: 2015 11 5 06:00:00 GPS Date/Time 05/11/15 06:00:00
2015 11 5 06:00:01 Manual 3D SV#'s 1 2 3 4 5 ( 5 )
2015 11 5 06:00:01 Lat 00'00.0000N Long 000'00.0000E Height 0m