Time interval magnetometer

Claim 2

Apparatus for measuring an external magnetic field comprising: a pulse generating means for providing a source of driving pulses; a monostable multivibrator having an input and an output, said monostable multivibrator input being coupled to said pulse generating means for producing output pulses of a predetermined time interval; sensing means having a saturable core of high permeability core material, exposed to the external field to be measured, said core means being coupled to said source of driving pulses, said driving pulses causing said saturable core to pass from saturation through a condition of nonsaturation including zero magnetization; the monostable multivibrator being preset so that the termination of each output pulse of a predetermined time interval occurs at the time the net field in the saturable core would be zero if no external magnetic field were present in the core; means coupled to said saturable core for detecting the point in time said core passes through said condition of zero magnetization; and means connected to said detecting means and connected to receive said output pulses of said monostable multivibrator for indicating the difference in time between the point in time said core passes through said condition of zero magnetization and the termination of one of said pulses of a predetermined time .

Claim 3

Apparatus for measuring an external magnetic field as defined in claim 1 but further characterized by having said means for detecting the point in time said core passes through said condition of zero magnetization comprising a threshold amplifier having an input and an output, said threshold amplifier input coupled to said saturable core; a Schmitt trigger having an input and an output, said Schmitt trigger input being coupled between said threshold amplifier output and said difference indicating means.

Claim 4

Apparatus for measuring an external magnetic field comprising: a pulse generating means for providing a source of driving pulses; a monostable multivibrator having an input and an output, said monostable multivibrator input being coupled to said pulse generating means for producing output pulses of a predetermined time interval; sensing means having a saturable core of high permeability core material, said core means being coupled to said source of driving pulses, said driving pulses causing said saturable core to pass from saturation through a condition of nonsaturation including zero magnetization; means coupled to said saturable core for detecting the point in time said core passes through said condition of zero magnetization; means coupled to said saturable core for detecting the point in time said core passes through said condition of zero magnetization; means connected To said detecting means and connected to receive said output pulses of said monostable multivibrator for indicating the difference in time between the point in time said core passes through said condition of zero magnetization and the termination of one of said pulses of a predetermined time interval whereby the measurement of said external magnetic field is proportional to the measured time interval; said means for indicating the difference in time comprises a first flip-flop having a pair of inputs, designated as d and f, a pair of outputs designated as Z or O and Z or 1, and a disable input designated as e; a second flip-flop having inputs d'' and f'', and Z'' or O output and a disable input e'' corresponding to said first flip-flop; The output of said monostable multivibrator being connected to said f'' input and to said d input of said second and said first flip-flops, respectively, to provide a reference point for the measurement of the time interval; said means for detecting the point in time said saturable core passes through said condition of zero magnetization having its output connected to the f input of said first flip-flop and to said d input of said second flip-flop, said first and said second flip-flop each having disabling means and being interconnected so that the one flip-flop will inhibit the change of state of the other for a complete cycle of said driving pulses, means connected to the O outputs of both flip-flops for measuring the time interval between the signals appearing on the respective O outputs, whereby, when a negative external magnetic field is present, said first flip-flop is being activated, the time interval of its period of activation is related to the amplitude of said negative external magnetic field and whereby, when a positive external magnetic field is present, said second flip-flop is activated, the time interval of its period of activation is related to the amplitude of said positive external magnetic field.

Claim 5

Apparatus for measuring an external magnetic field comprising: a pulse generating means for providing a source of driving pulses; a monostable multivibrator having an input and an output, said monostable multivibrator input being coupled to said pulse generating means for producing output pulses of a predetermined time interval; sensing means having a saturable core of high permeability core material, said core means being coupled to said source of driving pulses, said driving pulses causing said saturable core to pass from saturation through a condition of nonsaturation including zero magnetization; means coupled to said saturable core for detecting the point in time said core passes through said condition of zero magnetization; means coupled to said saturable core for detecting the point in time said core passes through said condition of zero magnetization; means connected To said detecting means and connected to receive said output pulses of said monostable multivibrator for indicating the difference in time between the point in time said core passes through said condition of zero magnetization and the termination of one of said pulses of a predetermined time interval whereby the measurement of said external magnetic field is proportional to the measured time interval; said means for indicating the difference in time comprises a first flip-flop having a pair of inputs, designated as d and f, a pair of outputs designated as Z or O and Z or 1, and a disable input designated as e; a second flip-flop having inputs d'' and f'', and Z'' or O output and a disable input e'' corresponding to said first flip-flop; The output of said monostable multivibrator being connected to said f'' input and to said d input of said second and said first flip-flops, respectively, to provide a reference point for the measurement of the time interval; said means for detecting the point in time said saturable core passes through said condition of zero magnetization having its output connected to the f input of said first flip-flop and to said d input of said second flip-flop, said first and said second flip-flop each having disabling means and being interconnected so that the one flip-flop will inhibit the change of state of the other for a complete cycle of said driving pulses, means connected to the O outputs of both flip-flops for measuring the time interval between the signals appearing on the respective O outputs, whereby, when a negative external magnetic field is present, said first flip-flop is being activated, the time interval of its period of activation is related to the amplitude of said negative external magnetic field and whereby, when a positive external magnetic field is present, said second flip-flop is activated, the time interval of its period of activation is related to the amplitude of said positive external magnetic field.

Claim 6

Apparatus for measuring an external magnetic field as defined in claim 3 but further characterized by having means for integrating said 1 output of said first flip-flop and said O output of said second flip-flop whereby the analogue output of said integrating means is indicative of said external magnetic field.

Claim 7

Apparatus for measuring an external magnetic field as defined in claim 4, but further characterized by having said means for detecting the point in time said core passes through said condition of zero magnetization comprising a threshold amplifier having an input and an output, said threshold amplifier input being coupled to said saturable core; a Schmitt trigger having an input and an output, said Schmitt trigger input being connected between said threshold amplifier output and said means for indicating the difference in time.

Claim 8

Apparatus for measuring an external magnetic field as defined in claim 5 wherein said means connected to said O outputs includes: a NOR gate having a pair of inputs and an output, one of said NOR gate inputs being coupled to said O output of said first flip-flop and said other NOR gate input being coupled to said O of said second flip-flop; and a digital time interval means having its input coupled to the output of said NOR gate.

Claim 9

Apparatus for measuring an external magnetic field as defined in claim 3 but further characterized by having said means for detecting the point in time said core passes through said condition of zero magnetization comprising: a threshold amplifier having an input and an output, said threshold amplifier input coupled to said saturable core; and a Schmitt trigger having an input and an output, said Schmitt trigger input being connected between said threshold amplifier output and said means for indicating the difference in time.

Claim 10

Apparatus for measuring an external magnetic field as defined in cLaim 7 wherein said means connected to said O outputs includes: a NOR gate having a pair of inputs and an output, one of said NOR gate inputs being coupled to said O output of said first flip-flop and said other NOR gate input being coupled to said O output of said second flip-flop; and a digital time interval means having its input coupled to the output of said NOR gate.

Claim 11

Apparatus for measuring an external magnetic field comprising: an astable multivibrator having an output; a linear sawtooth wave generator having an input and an output, said linear sawtooth wave generator input being coupled to said astable multivibrator output; a constant current driver having an input and an output, said constant current driver input being coupled to said linear sawtooth wave generator output; a single saturable core probe means coupled to said constant current driver output; a threshold amplifier having an input and an output, said threshold amplifier input being coupled to said saturable core; a Schmitt trigger having an input and an output, said Schmitt trigger input being coupled to said threshold amplifier output; a monostable multivibrator having an input and an output, said multivibrator input being coupled to said astable multivibrator output; a first flip-flop having a plurality of inputs and a pair of outputs designated as f input, d input and an e input, an O output and a 1 output, said first flip-flop f input being coupled to said Schmitt trigger output, said flip-flop d input being coupled to said monostable multivibrator output; a second flip-flop having inputs and outputs corresponding to those of said first flip-flop and designates as a f'' input, a d'' input and an e'' input, and an O output, said second flip-flop f'' input being connected to said monostable multivibrator output, said flip-flop d'' input being coupled to said Schmitt trigger output; means interconnecting said first and second flip-flops for holding the flip-flop which has not been triggered on to an off condition after the other of said flip-flops has been triggered on; a NOR gate having a pair of inputs and an output, one of said NOR gate inputs being connected to said first flip-flop O output and said other one of said NOR gate inputs connected to said second flip-flop O output; a digital time interval meter having its input connected to said NOR gate output; and an adding integrator having a pair of inputs said first input coupled to said first flip-flop 1 output and said second integrator input being coupled to said second flip-flop O output whereby the digital output of the digital time interval meter and the analogue output of the adding integrator are proportion to and a measurement of the external magnetic field.

Claim 12

Apparatus for measuring an external magnetic field comprising: an astable multivibrator having an output; a linear sawtooth wave generator having an input and an output, said linear sawtooth wave generator input being coupled to said astable multivibrator output; a constant current driver having an input and an output, said constant current driver input being coupled to said linear sawtooth wave generator output; a single saturable core probe means coupled to said constant current driver output; a threshold amplifier having an input and an output, said threshold amplifier input being coupled to said saturable core; a Schmitt trigger having an input and an output, said Schmitt trigger input being coupled to said threshold amplifier output; a monostable multivibrator having an input and an output, said multivibrator input being coupled to said astable multivibrator output; a first flip-flop having a plurality of inputs and a pair of outputs designated as f input, d input and an e input, an O output and a 1 output, said first flip-flop f input being coupled to said Schmitt trigger output, said flip-flop d input being coupled to said monostable multivibrator output; a second flip-flop having inputs and outputs corresponding to those of said first flip-flop and designates as a f'' input, a d'' input and an e'' input, and an O output, said second flip-flop f'' input being connected to said monostable multivibrator output, said flip-flop d'' input being coupled to said Schmitt trigger output; means interconnecting said first and second flip-flops for holding the flip-flop which has not been triggered on to an off condition after the other of said flip-flops has been triggered on; a NOR gate having a pair of inputs and an output, one of said NOR gate inputs being connected to said first flip-flop O output and said other one of said NOR gate inputs connected to said second flip-flop O output; a digital time interval meter having its input connected to said NOR gate output; and an adding integrator having a pair of inputs said first input coupled to said first flip-flop 1 output and said second integrator input being coupled to said second flip-flop O output whereby the digital output of the digital time interval meter and the analogue output of the adding integrator are proportion to and a measurement of the external magnetic field.