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Electric Field Echo Correlator

IP.com Disclosure Number: IPCOM000084356D
Original Publication Date: 1975-Oct-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Melcher, RL: AUTHOR [+2]

Abstract

A circuit is employed, using parametric electric field echoes generated in piezoelectric semiconductors to obtain a cross correlation between two signals.

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Electric Field Echo Correlator

A circuit is employed, using parametric electric field echoes generated in piezoelectric semiconductors to obtain a cross correlation between two signals.

In Fig. 1 is shown a piezoelectric crystal 2 to which are attached two electrodes 4 and 6. Two microwave generators 8 and 10 generate, respectively, microwave signals at frequencies omega(1) and omega(2) that are coupled to the crystal through capacitor 12. A DC pulse generator 14 is coupled to the crystal via inductor 16. Output signals from the crystal are sensed by receiver
18.

Figs. 2A and 2B are pulse sequence diagrams, useful in understanding the operation of the electric field echo correlator of Fig. 1. At time t=o, a microwave pulse of frequency omega(1) is applied to the piezolectric crystal so as to generate an acoustic wave of frequency omega(1) which propagates at the surface of such crystal for a time T, where T is the absorption time of the acoustic wave. At time t= tau, where tau < T, a second microwave electric field of frequency omega(2) is applied to the crystal and interacts parametrically with the acoustic wave at frequency omega(1).

Such parametric interaction leads to a backward propagating acoustic wave under the conditions where omega(2) = 2 omega(1)/m, and m = 1, 2, 3, 4, etc. However, when m is an odd number (1, 3, 5, etc.), the backward propagating effect is observed only when a DC pulse is applied at the same time that the omega(2) frequency pulse is applied.

The parametric interaction between omega(1) and omega(2) and...