Acoustic doppler wave recognition

Claim 2

A moving body indicator which will distinguish between approaching and receding bodies comprising: a. a transducing means for transmitting an ultrasonic signal at a certain frequency, b. a transducing means for receiving the reflected portion of said transmitted signal from a body, one of said transducing means comprising an electrically charged polymer foil, a thin coating of metal on one side thereof to which an electrode is attached, a metal plate forming a backing for said foil, and an electrode attached to said metal plate. c. first mixing means for deriving a Doppler signal which is the difference in frequency between the transmitted and received signals, first phase shifting means for shifting the phase of said transmitted signal from said transmitting means by a predetermined amount, d. second mixing means for driving a Doppler signal which is the difference in frequency between the transmitted signal phase shifted by a predetermined amount and the received signal, e. second phase shifting means for shifting the phase of the output signal from said second mixing means by a predetermined amount, f. correlating means for comparing the signals produced by said first mixing means and said second phase shifting means and which will produce a signal of one polarity when said compared signals are out of phase and of the opposite polarity when said signals are in phase, g. measuring means connected to the output of said correlator to determine whether the signals compared by said correlator means are in phase or out of phase. h. alarming means connected to the output of said correlator means to give an alarm signal when said measuring means measures certain prescribed values.

Claim 3

The moving body indicator of claim 1 wherein the correlating means includes a first coil connected to the output of said first mixing means and fixed in position, a second coil connected to the output of said second phase shifting means and force measuring means to indicate whether the signals in said first and second coils cause the coils to attract or Repel each other.

Claim 4

The moving body indicator of claim 2 wherein the force measuring means includes a bimorph piezoelectric element that is attached to the second coil and which will produce a signal of one polarity when the coils repel each other.

Claim 5

The moving body indicator of claim 3 wherein the first and second phase shifting means each delay the signal pi /2.

Claim 6

The moving body indicator of claim 4 wherein the measuring means includes an integrating circuit to integrate the signal produced by the piezoelectric element, D-C amplifying means connected to the output of said integrating circuit and meter means connected to measure the output of said D-C amplifier.

Claim 7

The moving body indicator of claim 5 wherein the integrating circuit is and RC circuit.

Claim 8

The moving body indicator of claim 1 wherein the transmitting and receiving means comprise a singular metallized foil electret transducer, said transducer providing both receiving and transmitting means. A moving body indicator which will distinguish between approaching and receding bodies comprising: a. a transducing means for transmitting a ultrasonic signal at a certain frequency, b. a transducingmeans for receiving the reflected portion of said transmitted signal from a body, one of said transducing means comprising an electrically charged polymer foil, a thin coating of metal on one side thereof to which an electrode is attached, a metal plate forming a backing for said foil, and an electrode attached to said metal plate, c. first mixing means for deriving a Doppler signal which is the difference in frequency between the transmitted and received signals, d. first phase shifting means for alternately producing a leading and lagging phase shift at a predetermined frequency smaller than the lowest expected Doppler frequency, e. second mixing means for deriving a Doppler signal which is the difference between the transmitter signal which has been phase shifted by said first phase shifting means and the received signal, f. second phase shifting means to shift the output of said second mixing means a predetermined amount, g. third phase shifting means to shift the output of said first mixing means a predetermined amount, h. correlating means for comparing the signals produced by said second and third phase shifting means and which will produce a signal of one polarity when said compared signals are out of phase and of the opposite polarity when said signals are in phase, i. measuring means connected to the output of said correlator to determine whether the signals compared to determine whether the signals compared by correlator means are in phase or out of phase. j. alarming means connected to the output of said correlator means to give an alarm signal when said measuring means measures certain prescribed values.

Claim 9

The moving body indicator of claim 8 wherein the correlating means includes a first coil connected to the output of said third phase shifting means and fixed in position, a second coil connected to the output of said second phase shifting means and a force measuring means to indicate whether the signals of said first and second coils cause the coils to attract or repel each other.

Claim 10

The moving body indicator of claim 9 wherein the force measuring means includes a bimorph piezoelectric element that is attached to the second coil and which will produce a signal of aone polarity when the coils attract each other and a signal of the opposite polarity when the coils repel each other.

Claim 11

The moving body indicator of claim 10 wherein the first phase shifting means will alternately shift the signal by a value of pi /2.

Claim 12

The moving body indicator of claim 11 wherein the second phase shifting means will delay the signal by pi /4.

Claim 13

The moving body indicator of claim 12 wherein the third phase shifting means includes an A-C amplifier connected to amplify the signal produced by the piezoelectric element, an Integrating circuit to integrate the output of the amplifier and a rectifier to change the integrated signal to a D-C signal, and meter means to measure the D-C signal and to indicate whether the body is approaching or receding from the moving body indicator.