Signal translating apparatus using surface wave acoustic device

Claim 2

In a wave signal apparatus for translating a program signal, an arrangement for controlling an operating characteristic of said apparatus comprising: an acoustic-surface-wave propagating medium; an input transducer coupled to a first portion of said medium and responsive to an applied signal for launching and acoustic surface wave in said medium; means for applying said program signal to said input transducer; an output transducer coupled to a second portion of said medium and responsive to acoustic surface waves launched therein for deriving an output signal; a control transducer coupled to a third portion of said medium located across the path of acoustic wave propagation from said input to said output transducers and effective to control a characteristic of wave transmission in said medium and said operating characteristic of said apparatus in accordance with the effective impedance represented by said control transducer; a variable load impedance coupled across said control transducer to determine the effective impedance thereof; and means for adjusting said load impedance to control said operating characteristic of said apparatus.

Claim 3

Apparatus as defined in claim 1 in which said load impedance includes a field-effect transistor.

Claim 4

Apparatus as defined in claim 1 in which said control transducer includes a pair of interleaved combs of electrodes and in which said load impedance includes a layer of semiconductive material disposed across electrically opposing ones of said electrodes, and at least one gating element, responsive to said adjusting means for varying the conductivity between said opposing electrodes, disposed on said layer.

Claim 5

Apparatus as defined in claim 1 in which said control transducer controls the amplitude of said waves transmitted to said output transducer.

Claim 6

Apparatus as defined in claim 1 in which said control transducer controls the phase of said waves transmitted to said output transducer.

Claim 7

In a color television receiver for utilizing a program signal having a chroma signal component angle-modulated with color information, a chroma-demodulation system comprising: an acoustic-surface-wave propagating medium; an input transducer coupled to said medium and extending across a wave propagation path for launching acoustic surface waves along said path in response to applied signals; a plurality of output transducers, disposed in nonoverlapping relation across said path and individually coupled to respective portions of said medium for developing a corresponding plurality of output signals; an amplifier coupled to one of said output transducers and constituting therewith a feedbaCk path for applying a first one of said output signals to said input transducer with a phase, determined in part by the spacing of said one output transducer along said path from said input transducer, to sustain the generation of oscillations; a chroma demodulator for receiving said chroma signal component; and means coupled to at least two others of said output transducers for deriving two others of said output signals for application to said demodulator as demodulation signals of essentially equal amplitude, said two other transducers having different spacings along said path from said input transducer related to one another to establish a predetermined relative phase for said demodulation signals.

Claim 8

In a color television receiver for utilizing a program signal having a chroma signal component angle-modulated with color information, a chroma-demodulation system comprising: an acoustic-surface-wave propagating medium; an input transducer coupled to said medium and extending across a wave propagation path for launching acoustic surface waves along said path in response to applied signals; a plurality of output transducers, disposed in nonoverlapping relation across said path and individually coupled to respective portions of said medium for developing a corresponding plurality of output signals; an amplifier coupled to one of said output transducers and constituting therewith a feedbaCk path for applying a first one of said output signals to said input transducer with a phase, determined in part by the spacing of said one output transducer along said path from said input transducer, to sustain the generation of oscillations; a chroma demodulator for receiving said chroma signal component; and means coupled to at least two others of said output transducers for deriving two others of said output signals for application to said demodulator as demodulation signals of essentially equal amplitude, said two other transducers having different spacings along said path from said input transducer related to one another to establish a predetermined relative phase for said demodulation signals.

Claim 9

A chroma demodulator as defined in claim 6 for using a chroma signal having color-synchronizing components which further includes: a control transducer coupled to said medium in the path of said waves between said input transducer and said output transducers and effective to control the phase of said acoustic waves in accordance with the effective impedance represented by said control transducer; a variable load impedance coupled across said control transducer to determine the effective impedance thereof; a phase detector responsive to said synchronizing signal component and to one of said output signals for developing a phase-control potential; and means responsive to said phase-control potential for adjusting said load impedance to maintain a predetermined phase

Claim 10

A chroma demodulator in accordance with claim 6 in which the distance from said input transducer to one of said two other output transducers exceeds the distance from said input transducer to the other of said two output transducers by a distance effecting equal to one-fourth wavelength of said acoustic waves at the frequency of said demodulation signals.