| 摘要 |
A compass dither device for use with a magnetic compass heading sensor unit for marine seismic streamers and the like having interrogating circuitry associated with the heading sensor to periodically provide a trigger pulse for interrogating a compass heading sensing components in the heading sensory unit and provide compass heading signals indicative of the heading of the compass the the time of interrogation, the compass dither device including a housing for the magnetic compass heading sensor unit having a dither coil encircling the portion where the headings sensory unit is positioned. Electronic dither circuitry produces a dither pulse having a pre-selected time relation with periodic interrogation of the heading sensor and causes current to be passed through the dither coil around the compass in a first direction and then in the opposite direction for a preselected time duration to activate the coil to provide a slight magnetic field causing the compass to move slightly to overcome any effects of static friction which might affect accuracy of compass heading signals upon interrogation.
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