Abstract: An inductive magnet sensor has two identically wound magnetic antennae connected in series, out of phase, spaced axially from one another, and placed outside and parallel to the axis of a magnetic pipe so that induced noise voltages from the symmetrical noise magnetic flux of the pipe mostly cancel, leaving the responsiveness of the antennae undiminished to sense the non-symmetrical magnetic flux from a permanent magnet or a signal from a transmitter passing through the pipe. The enhanced signal of each of these antennae is then resistively attenuated, one fixed and the other adjustable, to further enhance the cancellation after placement of the sensor outside of the pipe. This balance adjustment improves the signal to noise ratio of the combined signal and the sensor is adjustably resistively attenuated to set the gain to enhance the dynamic range after mounting on the pipe.

Abstract: An apparatus for measuring one or more parameters of the subsurface environment, and telemetering one or more parameters of the subsurface environment to the surface. Apparatus at the surface includes a source of intermediate frequency and voltage, electrical energy for transmission down one or more conductors of a power cable or separate instrument wire to a downhole instrument package. This intermediate frequency voltage is converted to a power supply voltage for generating a high frequency FM signal, in accordance with the magnitude of one or more parameters of the environment. This frequency modulated signal is sent to the surface over the conductors of the power cable and ground. At the surface the signal is demodulated to produce a signal indicative of the transmitted parameter.

Abstract: An apparatus for measuring one or more parameters of the subsurface environment, and telemetering one or more parameters of the subsurface environment to the surface. Apparatus at the surface includes a source of intermediate frequency and voltage, electrical energy for transmission down one or more conductors of a power cable or separate instrument wire to a downhole instrument package. This intermediate frequency voltage is converted to a power supply voltage for generating a high frequency FM signal, in accordance with the magnitude of one or more parameters of the environment. This frequency modulated signal is sent to the surface over the conductors of the power cable and ground. At the surface the signal is demodulated to produce a signal indicative of the transmitted parameter.

Abstract: An apparatus for measuring one or more parameters of the subsurface environment, and telemetering one or more parameters of the subsurface environment to the surface. Apparatus at the surface includes a source of intermediate frequency and voltage, electrical energy for transmission down one or more conductors of a power cable or separate instrument wire to a downhole instrument package. This intermediate frequency voltage is converted to a power supply voltage for generating a high frequency FM signal, in accordance with the magnitude of one or more parameters of the environment. This frequency modulated signal is sent to the surface over the conductors of the power cable and ground. At the surface the signal is demodulated to produce a signal indicative of the transmitted parameter.