The Applied Physics Systems Model 544 heading sensor measures roll, pitch, and azimuth. It is designed for directional drilling in oil and gas and construction. It can also be used for defense applications such as harbor surveillance to listen for enemy submarines.Read More
The Model 544 consists of a 3-axis fluxgate magnetometer and a 3-axis accelerometer that output 16-bit digital data representing the magnetometer and accelerometer readings.
The Model 544 transmits the roll, pitch, and azimuth orientation angles. These angles are calculated before they are transmitted from the accelerometer and magnetometer sensor output data.
Two communication protocols are available over a bidirectional serial data link to the surface: ASCII and binary at up to 9600 baud. An ASCII data stream can be easily displayed on a video terminal while binary is used for high speed computer to computer interchange.
The Model 544 scale factors, zero bias factors and alignment angles are measured by placing the unit in precision rotational and magnetic field applying fixtures. Scale and offset calibration factors are measured over the 0°C to 70°C temperature range for the standard 544 sensor. The Model 544H calibrates the sensor over the temperature range from 0°C to 125°C.
The integral microprocessor corrects for alignment, scale, and offset factors within the temperature range before outputting data. The Model 544 calibration data is stored in the EEROM, which is user accessible.
The magnetometer noise level is 5 μGauss and the accelerometer noise level is 0.2 milligee. The maximum data throughput is approximately 3 readings per second when all 6 outputs are transmitted. The temperature compensated Model 544 roll, pitch, and azimuth sensors have an overall accuracy of ±0.4° for roll and pitch and ±1.2° for azimuth.
The long version of the unit provides greater separation of the sensors and electronics for more accurate data measurement.