Operating Instructions and Installation Instructions

ComNav Vector G2/G2B Installation & Operation Operation

Document PN 29010078 V2.0 - 43 -

DRAFT #3 – 29 May 2009

Supplemental Sensors

Integrated inside the Vector G2’s enclosure, on the main printed circuit board, are two

sensors. One sensor is an accelerometer, which measures the tilt of the G2’s enclosure;

the other sensor is a solid-state gyro, which measures the rate of turn.

Both sensors are enabled by default. Each sensor may be turned on or off individually;

however, the full functionality of the G2 is realized only when both are used.

Both sensors act to reduce the RTK search even further, which improves heading

start-up and reacquisition times, and also improve the reliability & accuracy of selecting

the correct heading solution, by eliminating other possible but erroneous solutions.

Tilt-aided RTK

The Vector G2’s internal tilt sensor constrains the RTK heading solution to less than the

full area of the surface of the search sphere associated with just a fixed antenna

separation, since the G2 knows – by reading the tilt sensor – the approximate inclination

of the Secondary GPS antenna with respect to the Primary.

The search volume defined by the tilt sensor only (i.e., not factoring in the gyro) will be

reduced to a horizontal ring on the surface of the sphere – a considerably smaller area

than the full surface of the sphere, as can be seen in the figure below.

Figure 17 – Tilt-aided Search

The tilt sensor is factory calibrated.

After installation, or after a long period of time that the G2 is in use, or in circumstances

where the G2 encounters repeated wide variations in operating &/or storage temperature,

it may be necessary to re-calibrate the tilt sensor.

The tilt measurements from the sensor may also be useful directly, in some applications

of the G2, in addition to or instead of the Pitch/Roll data that the G2 computes while

doing the RTK.

The GPS Technical Reference manual describes the commands and methodology

required to query the tilt sensor, to recalibrate it, and to enable or disable it.