A system includes a magnetic field sense element for detecting an external magnetic field and a magnetic field source proximate the magnetic field sense element for providing a reference magnetic field. The magnetic field sense element produces a composite signal having reference and measurement signal portions, the reference signal portion being indicative of the reference magnetic field and the measurement signal portion being indicative of the external magnetic field. A power supply provides a supply current through the magnetic field source for continuously generating the reference magnetic field while the system is in an operational mode. A processing circuit processes the composite signal to produce a measurement output signal indicative of the external magnetic field. A qualification circuit, coupled with the processing circuit at multiple test points, detects the reference signal portion at the multiple test points and determines operability of the system from the detected reference signal portion.

An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a platform; a coil for measuring EM signals; and first to third suspension mechanisms located between the platform and the coil so that the coil oscillates relative to the platform, and the first to third suspension mechanisms attenuate motion induced noise introduced by towing the receiver system above ground.

An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a platform; a coil for measuring EM signals; and first to third suspension mechanisms located between the platform and the coil so that the coil oscillates relative to the platform, and the first to third suspension mechanisms attenuate motion induced noise introduced by towing the receiver system above ground.

A system includes a magnetic field sense element for detecting an external magnetic field and a magnetic field source proximate the magnetic field sense element for providing a reference magnetic field. The magnetic field sense element produces a composite signal having reference and measurement signal portions, the reference signal portion being indicative of the reference magnetic field and the measurement signal portion being indicative of the external magnetic field. A power supply provides a supply current through the magnetic field source for continuously generating the reference magnetic field while the system is in an operational mode. A processing circuit processes the composite signal to produce a measurement output signal indicative of the external magnetic field. A qualification circuit, coupled with the processing circuit at multiple test points, detects the reference signal portion at the multiple test points and determines operability of the system from the detected reference signal portion.

An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a platform; a coil for measuring EM signals; and first to third suspension mechanisms located between the platform and the coil so that the coil oscillates relative to the platform, and the first to third suspension mechanisms attenuate motion induced noise introduced by towing the receiver system above ground.

An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a platform; a coil for measuring EM signals; and first to third suspension mechanisms located between the platform and the coil so that the coil oscillates relative to the platform, and the first to third suspension mechanisms attenuate motion induced noise introduced by towing the receiver system above ground.

An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a platform; a coil for measuring EM signals; and first to third suspension mechanisms located between the platform and the coil so that the coil oscillates relative to the platform, and the first to third suspension mechanisms attenuate motion induced noise introduced by towing the receiver system above ground.

An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a platform; a coil for measuring EM signals; and first to third suspension mechanisms located between the platform and the coil so that the coil oscillates relative to the platform, and the first to third suspension mechanisms attenuate motion induced noise introduced by towing the receiver system above ground.

An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a platform; a coil for measuring EM signals; and first to third suspension mechanisms located between the platform and the coil so that the coil oscillates relative to the platform, and the first to third suspension mechanisms attenuate motion induced noise introduced by towing the receiver system above ground.

An electromagnetic (EM) receiver system for measuring EM signals. The EM receiver system includes a platform; a coil for measuring EM signals; and first to third suspension mechanisms located between the platform and the coil so that the coil oscillates relative to the platform, and the first to third suspension mechanisms attenuate motion induced noise introduced by towing the receiver system above ground.