Geometrics G-822A Cesium Magnetometer

The model G-822A cesium airborne magnetometer provides unmatched versatility of performance, size, function, and cost effectiveness. The G-822A sensor uses a precise, proven design with carefully selected and tested components to ensure the very best specifications in sensitivity, noise, heading error and absolute accuracy.

The G-822A magnetometer outputs a Larmor frequency that corresponds to the strength of the local magnetic field. This Larmor frequency is counted by a user-supplied counter or a professional compensator such as the RMS Instruments AARC500 Automatic Digital Compensator.

The sensor and electronics package is weatherproof, temperature controlled, and delivers full performance under extreme operating conditions. With a proven record of stable and reliable operation over long periods, the G-822A is the industry standard for manned aircraft and large-unmanned aircraft surveys.

Features and benefits

Versatile Multi-Sensor Array Capability: This instrument can be used in fixed wing, helicopter or land applications to fit any surveyor’s needs.
Highest Sensitivity: Measure the smallest variations in the magnetic field.
Fast Sampling: Better coverage at faster speeds.
Very Low Heading Error: Get very clean, repeatable measurements without fear of instrument noise impacting the data.
Low AC Field Interference: Survey next to power lines when necessary.
Rugged and Reliable: Weatherproof. Survives three-foot drop onto hard surface.
Ultra-stable: No need to calibrate sensors.
Export Version Available: Use anywhere in the world without need for an export license (except embargoed countries). See specifications.

Technical Details

- Operating Principle: Self-oscillating split-beam Cesium Vapor (non-radioactive)
- Operating Range: 20,000 to 100,000 nT
- Operating Zones: The earth’s field vector should be at an angle greater than 6° from the sensor’s equator and greater than 6° away from the sensor’s long axis. Automatic hemisphere switching.
- Sensitivity: < 0.001 nT/√Hz rms. Typically 0.003 nT P-P at a 0.1 second sample rate 0.02 nT P-P for CM-201
- Heading Error: ± 0.15 nT (over entire 360° polar and equatorial spin)
- Absolute Accuracy: < 3 nT throughout range
- Output: Cycle of Larmor frequency = 3.498572 Hz/nT, 2 V P-P coupled through the sensor power input

Mechanical

- Sensor: 2.375” (60.32 mm) diameter, 5.75” (146 mm) long, 12 oz. (339 g) - any orientation in 7” (177.8 mm) diameter stinger
- Sensor Electronics: 2.5” (63.5 mm) diameter, 11” (279.4 mm) long, 22 oz. (623 g)
- Cables:
- Sensor to electronics: Standard 162 in. (13 ft. 6 in. or 4.1 m). Other lengths available from 2.4ft. (0.75m) at 40 in. (1 m) increments with connector on electronics end. Note: Cable lengths are approximate due to cable dielectric variations
- Sensor Electronics to Counter: Standard 10 m, up to 165 ft. (50 m) (Coax with signal superimposed on power, requires decoupler board or box.)
- Operating Temperature: -30°F to +122°F (-35°C to +50°C)
- Storage Temperature: -48°F to +158°F (-45°C to +70°C)
- Altitude: Up to 30,000 ft. (9,000 m)
- Weatherproof: O-Ring sealed for operation in rain or 100% humidity.
- Power: 24 to 32 VDC, 1 amp at turn-on and 0.5 amp thereafter.

Accessories

Standard: Power/Larmor coaxial cable (electronics to counter), standard length 10m, maximum 50m, spare O rings, operation manual and carrying/storage case.
Optional:
Signal/Power Decoupler, board or multi-channel box: Separates the Larmor signal from the power (28 V) to enable connection to Customer supplied counter.
Internal Decoupler: P/N 27504 - up to two sensor installation
External Decoupler: P/N 27560 - three and four sensor installation
Internal CM-221 Counter: See G-823A Magnetometer specifications
Stinger, Wingtip, Bird: Contact Factory for complete system integration information.