Unicont SPb Ltd
Technical Documentation ADPC-101
Page 16
8.8.4.
NMEA LOG fmt
– format of output NMEA line with current speed
value:
Disabled
- output of speed value is disabled
VMVTG
- $VMVTG,,,,,x.x,N,,*cs
VMVBW
- $VMVBW,x.x,,A,,,*cs (NMEA v 2.0)
IIVTG -
$IIVTG,,,,,x.x,N,,*cs
IIVBW -
$IIVBW,x.x,,A,,,*cs
SIVHW
- $SIVHW,x.x,T,,,x.x,N,,*cs (mixed format: speed and heading
value in one NMEA line)
VMVBW
- $VMVBW,x.x,,A,,,A,,V,,V*cs (NMEA v 2.3)
------------------------------
cs – checksum.
8.9
Non-authenticity of data
1. Non-authenticity of gyrocompass data.
Non-authenticity is defined by absence of reference signal.
As far as stepper type gyrocompass is concerned – lack of required level;
As far as synchro type gyrocompass is concerned – lack of sine signal differentials,
emergence of timing jitter (breaking of sector alteration priority) or presence of inadmissible
states.
2. Non-authenticity of log data.
Non-authenticity is determined provided that measured speed is 100 knots and more.
In case when gyrocompass and/or log data are not trustworthy, relevant NMEA line is
stopped for transmission to serial port and display shows ‘?’ (question) – at the beginning of
relevant line, if alarm option is setted, device is emitted sound
When trustworthy data are displayed, data transmission is resumed.
