Synchronous am demodulator

Claim 2

A demodulator system for amplitude demodulation of an input modulated signal comprising: a transistor having a base, an emitter and a collector, the modulated input signal being applied to the base and the demodulated signal output being taken from the collector; a gate connected between the transistor emitter and ground, said gate having an off-condition to cause said transistor to be inoperable and a conduction-condition to provide a current path for said transistor and thereby enabling said transistor to be operative for demodulating said modulated signal; and a source of a reference continuous wave (CW) signal coupled to said gate, whereby one portion of said CW signal causes said gate to operate in said conduction-condition and the remaining portion of said CW signal causes said gate to be in said offcondition.

Claim 3

The demodulator system of claim 1 wherein said gate comprises: a second transistor having a base, emitter and collector, the emitter being grounded, the collector being connected to the emitter of said first-mentioned transistor, said CW reference signal being applied to the base of said second transistor.

Claim 4

An AM demodulator and amplifier for synchronously demodulating a double sideband suppressed carrier wave having modulation at two different phases, comprising: a first and a second transistor, the transistors having respectively base, emitter and collector leads, the emitter of the first transistor being connected to the collector of the second transistor; bias means for biasing the first transistor for Class A operation, the modulated signal being applied to the base of the first transistor and the demodulated output signal being obtained from the collector lead of the first transistor; a carrier signal source, the carrier signal being applied to the base of the second transistor, the emitter of said second transistor being substantially at ground potential; and means for biasing the second transistor to cut off during one portion of said carrier wave cycle and saturating said second transistor during the remaining portion of said cycle, whereby the first transistor demodulates and amplifies the modulated signal during said one portion of the carrier cycle and is quiescent during said remaining portion of the carrier cycle.

Claim 5

An AM demodulator and amplifier for synchronously demodulating a double sideband suppressed carrier wave having modulation at two different phases, comprising: a first and a second transistor, the transistors having respectively base, emitter and collector leads, the emitter of the first transistor being connected to the collector of the second transistor; bias means for biasing the first transistor for Class A operation, the modulated signal being applied to the base of the first transistor and the demodulated output signal being obtained from the collector lead of the first transistor; a carrier signal source, the carrier signal being applied to the base of the second transistor, the emitter of said second transistor being substantially at ground potential; and means for biasing the second transistor to cut off during one portion of said carrier wave cycle and saturating said second transistor during the remaining portion of said cycle, whereby the first transistor demodulates and amplifies the modulated signal during said one portion of the carrier cycle and is quiescent during said remaining portion of the carrier cycle.

Claim 6

A synchronous AM demodulator amplifier system for color television receivers in which the received chrominance signal is a double sideband suppressed carrier wave modulated on two axes, and in which a locally generated continuous wave carrier signal is provided within the receiver for reinsertion into the suppressed carrier chrominance signal during demodulation, the invention comprising in combination identical first and second demodulation and amplification circuits, the circuits comprising respectively: first transistors having base, emitter and collector leads, the first transistors respectively being biased for Class A operation; second traNsistor means connected to the emitter leads of the respective first transistors, the respective second transistors being biased for conduction during one portion of a CW carrier signal cycle and for cutoff during the remaining portion of the cycle, the chrominance signals being applied to the respective first transistor bases, the demodulated output signals being obtained from the collector leads of the respective first transistors, the CW carrier signal being applied directly to the second transistor means in the first circuit, and being applied after a 90* phase shift to the second transistor means in the second circuit, whereby the chrominance signal is demodulated in said first circuit during said one portion of the CW cycle and the chrominance signal is demodulated in said second circuit during said one portion of said phase shifted CW signal.

Claim 7

A synchronous AM demodulator amplifier system for color television receivers in which the received chrominance signal is a double sideband suppressed carrier wave modulated on two axes, and in which a locally generated continuous wave carrier signal is provided within the receiver for reinsertion into the suppressed carrier chrominance signal during demodulation, the invention comprising in combination identical first and second demodulation and amplification circuits, the circuits comprising respectively: first transistors having base, emitter and collector leads, the first transistors respectively being biased for Class A operation; second traNsistor means connected to the emitter leads of the respective first transistors, the respective second transistors being biased for conduction during one portion of a CW carrier signal cycle and for cutoff during the remaining portion of the cycle, the chrominance signals being applied to the respective first transistor bases, the demodulated output signals being obtained from the collector leads of the respective first transistors, the CW carrier signal being applied directly to the second transistor means in the first circuit, and being applied after a 90* phase shift to the second transistor means in the second circuit, whereby the chrominance signal is demodulated in said first circuit during said one portion of the CW cycle and the chrominance signal is demodulated in said second circuit during said one portion of said phase shifted CW signal.

Claim 8

A chrominance signal demodulator and amplifier system for color television receivers wherein the received chrominance signal is a double sideband suppressed carrier wave signal modulated on two axes, including: a continuous wave (CW) reference carrier signal generator; a phase shift means having an input and an output, said CW generator being coupled to said input, said output providing substantially said CW signal but phase shifted a predetermined number of degrees; a first and a second demodulator circuit, each of said demodulator circuits comprising: a first transistor having a base, emitter and collector, said chrominance signal being applied to the base; a second transistor having a base, emitter and collector, the collector of the second transistor being linked to the emitter of the first transistor, the emitter of the second transistor being substantially at circuit ground, said reference CW signal being applied to the base of the second transistor of said first demodulator circuit and said CW signal from the output of said phase shift means being applied to the base of the second transistor of said second demodulator circuit, said second transistor of each demodulator circuit being cutoff during one portion of the corresponding CW signal to cause the corresponding first transistor to be inoperable, said second transistor of each demodulator circuit being saturated during the remaining portion of the CW signal to enable the respective first transistors to be operative and thereby cause the corresponding input chrominance signal to be demodulated

Claim 9

A chrominance signal demodulator and amplifier system for color television receivers wherein the received chrominance signal is a double sideband suppressed carrier wave signal modulated on two axes, including: a continuous wave (CW) reference carrier signal generator; a phase shift means having an input and an output, said CW generator being coupled to said input, said output providing substantially said CW signal but phase shifted a predetermined number of degrees; a first and a second demodulator circuit, each of said demodulator circuits comprising: a first transistor having a base, emitter and collector, said chrominance signal being applied to the base; a second transistor having a base, emitter and collector, the collector of the second transistor being linked to the emitter of the first transistor, the emitter of the second transistor being substantially at circuit ground, said reference CW signal being applied to the base of the second transistor of said first demodulator circuit and said CW signal from the output of said phase shift means being applied to the base of the second transistor of said second demodulator circuit, said second transistor of each demodulator circuit being cutoff during one portion of the corresponding CW signal to cause the corresponding first transistor to be inoperable, said second transistor of each demodulator circuit being saturated during the remaining portion of the CW signal to enable the respective first transistors to be operative and thereby cause the corresponding input chrominance signal to be demodulated

Claim 10

The signal demodulator and amplifier system of claim 5 wherein the collector of the first transistor of the first demodulator circuit is connected to the ''''red'''' color grid for a kinescope for color television and the collector of the first transistor of the second demodulator circuit is connected to the ''''blue'''' color grid for said kinescope, said collector of the first transistor of each of said demodulator circuits being connected to a summation circuit for deriving a signal at the output of the summation circuit for green, said output being connected to the ''''green'''' color grid of said kinescope.