TECHNICAL NOTES
- CT2
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TECHNICAL NOTES
- CT2
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The concept of monitoring the disturbance of the earth's magnetic
field by a submarine, is complicated by the interference of the aircraft
itself. RMS Instruments produces the AADCII which corrects in real-time,
the interference caused by the aircraft. It is a fully automatic compensator,
very easy to use, and relatively inexpensive.
The AADCII is used in magnetometer and gradiometer (multisensor) systems, to provide real-time compensation of the interference caused by the aircraft or helicopter, as they maneuver in the earth's magnetic field. An interference model of up to 30 terms compensates for permanent and induced magnetism, Eddy Current effects, and for orientation errors in the magnetic sensors. The AADCII is capable of processing the magnetometer Larmor frequency signals to a resolution of 0.001 nT over a bandwidth of DC to 0.9 Hz without aliasing or phase distortion. For ASW applications, various filter responses are available. The compensator accuracy of the system is such that it allows the sensitivity of the optically pumped magnetometers, typically 0.003 nT p-p to be fully realized.
Calibration of the AADCII requires only 6 to 8 minutes of maneuvering, therefore it reduces air time and cost. . The solution is obtained immediately, and is extremely robust, meaning that compensation will be effective in areas of differing background geology, and over a wide range of total field.
Over the years, the AADCII has proven itself in single magnetometer installations, and in high accuracy gradiometer systems, comprising up to four magnetometers. At present, the RMS Instruments' AADCII is the only operating system available for up to a four magnetometer sensor installation from a single console.
Its performance, coupled with its ease of installation, ease of calibration (fully automatic), and high MTBF, have made it the industry standard for aeromagnetic resources exploration and geophysical mapping.
The features, capability, and performance of the AADCII, plus its relative low cost, makes it ideally adaptable to military detection applications. When combined with a high sensitivity, low cost non-oriented (strapped-down) optically pumped magnetometer, detection performance has been demonstrated that surpasses that of high cost military systems.
In a gradiometer configuration, with one magnetometer at each wing tip of an ASW aircraft, the AADCII can provide not only target detection, but when driving a simple display, can indicate the position of a target with respect to the aircraft. This feature offers a tremendous operational advantage over single magnetometer systems.
Another attractive feature is that a number of compensation solutions can be stored (up to thirteen) and recalled as required. This is particularly useful in overcoming changes to the magnetic signature of the aircraft, such as when weapons or stores are deployed.
In addition, a highly effective recognition algorithm, that separates a target from the background geology could be made available for the AADCII MAD installation.
A basic single sensor system would consist of the following:
In order to obtain maximum performance, some calibration maneuvering is necessary. The AADCII is self-calibrating, requiring only a few minutes. This will dramatically reduce the air time and costs now required. The time saved will also reduce air frame stress and pilot fatigue, increasing productive flying time.
These systems are long term investments, and our AADCII, with one or two of the new technology, high sensitivity Cesium or Helium magnetometers, would provide the Military with a cost effective MAD capability.
To view diagrams of typical configurations, click on the links below:
| Typical MS-MAD (Multisensor) Configuration |
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