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Figure 1.2: Hardware Implementation

"... in the Edinburgh phantom precise quadrature phase shifts at each scanner frequency are achieved by using parallel tuned R-L-C circuits for the ultrasonic signals.

At the resonant frequency of each such circuit, two signals in quadrature phase with one another but of equal amplitude are drawn from the inductor and capacitor using high impedance buffers. The inductor is slightly variable to allow fine tuning of each circuit for precise quadrature phase shifting."