Concealed structure locating and surveying exciter

Claim 1

An inductive exciter means which has the capacity to stimulate sympathetic electromagnetic vibrations of a constant frequency in a concealed structure for the purpose of locating and surveying the said concealed structure including in combination: (a) stabilized oscillator means operative to produce a source of first alternating current frequency, (b) alterative reforming means coupled to the output of said oscillator means wherein said reforming means is operative to produce a source of squared waveform second alternating current frequency signal the periodicity of which is derived from the said first alternating current frequency, wherein said reforming means includes an output means therefrom for providing said signal, (c) current amplifier means, including an input means for accepting voltage pulses, said current amplifier means being operative to increase the elctrical amplitude of the said voltage pulses at the output of the said amplifier, (d) resonant winding means of goodly size and high operating "Q" loosely inductively coupled to the said current amplifier means output and operative so as to cause an electromagnetic field of large proportions and area, such field being caused to be sympathetically coupled into the concealed structure through suitable orientation of the said resonant winding so as to inductively excite the said structure to again reradiate electromagnetic field lines along the length and breadth of the said structure at a replica rate of the originating inductive signal frequency, (e) a source of direct current power connected so as to be operative to provide the electrical operating potentials as required for the proper functioning of the said stabilized oscillator means, said alterative reforming means, and said current amplifier means, and pulse shaper means, consisting of at least one input and at least one output, wherein said pulse shaper is comprised of at least one resistor and at least one capacitor arranged in the general form of a differentiator with the input thereto operatively coupled to the said source of squared waveform second alternating frequency signal provided by the said reforming means output, and with the output thereto coupled to the said current amplifier means input, the time constant of said differentiator resistor and capacitor being somewhat shorter than the half-cycle period of the output signal from the reforming means, wherein said pulse shaper means produces output voltage pulses, in response to said inputed squared waveform second alternating frequency signal which are improved in waveform efficaciousness by reducing the width, or "on time", of the exciting drive pulse delivered through the said current amplifier means to the said resonant winding means until the amplitude of the induction field emanating from said winding means reaches a maximum, whereupon the said pulse width is, in a small degree, re-increased until the said issuing field just starts to decline in amplitude by not more than a few percent, such condition being found to be that which is necessary to provide sufficient power from the said current amplifier to overcome the losses sustained in the energy storage ability of the high "Q" resonant winding, yet prevent the said current amplifier from shunting, or loading, and thereby dissipating any significant portion of the stored energy contained in the said resonant winding.