Receiver for compatible AM stereo signals

Claim 2

An AM receiver for receiving compatible stereo signals having the form (1+L +R)cos(ω c t+φ) where L and R represent first and second intelligence signals, ω c t is a carrier frequency signal, and φ is arc tan {(L-R)/ (1+L +R)} and comprising in combination: input means for receiving said signal and deriving therefrom an intermediate frequency signal; envelope detector means coupled to the input means for detecting the amplitude modulation on the intermediate frequency signal; synchronous detector means coupled to the input means for providing an output proportional to (L-R)cos φ; corrector means coupled to the synchronous detector means for providing an output proportional to L-R; and matrix means for processing the L-R; and L+R signals to provide separate L and R outputs.

Claim 3

An AM receiver for receiving compatible stereo signals having the form (1+L +R)cos(ω c t +φ) where L and R represent first and second intelligence signals, ω c t is a carrier frequency signal, and φ is arc tan [(L+R)/ (1+L +R)] and comprising in combination: input means for receiving said signal and deriving therefrom an intermediate frequency signal; envelope detector means coupled to the input means for detecting the amplitude modulation on the intermediate frequency signal; first circuit means coupled to the input means for providing an output related to the phase of the received carrier signal; second circuit means for providing an output related to the phase of the unmodulated carrier signal; third circuit means for providing a signal proportional to cos φ; synchronous detector means coupled to the output of the second circuit means for providing an output proportional to (L-R) cos φ; divider means coupled to the synchronous detector means and to the third circuit means for providing an output proportional to (L-R); and matrix means for processing the L-R and L+R signals to provide separate L and R outputs.

Claim 4

An AM receiver for receiving compatible stereo signals having the form (1+L +R)cos(ω c t +φ) where L and R represent first and second intelligence signals, ω c t is a carrier frequency signal, and φ is arc tan [(L+R)/ (1+L +R)] and comprising in combination: input means for receiving said signal and deriving therefrom an intermediate frequency signal; envelope detector means coupled to the input means for detecting the amplitude modulation on the intermediate frequency signal; first circuit means coupled to the input means for providing an output related to the phase of the received carrier signal; second circuit means for providing an output related to the phase of the unmodulated carrier signal; third circuit means for providing a signal proportional to cos φ; synchronous detector means coupled to the output of the second circuit means for providing an output proportional to (L-R) cos φ; divider means coupled to the synchronous detector means and to the third circuit means for providing an output proportional to (L-R); and matrix means for processing the L-R and L+R signals to provide separate L and R outputs.

Claim 5

An AM receiver according to claim 2 wherein the second circuit means is coupled to an output of the first circuit means.

Claim 6

An AM receiver according to claim 2 wherein the third circuit means is coupled to outputs of the first and second circuit means.

Claim 7

An AM receiver for receiving compatible stereo signals having the form (1+L +R)cos(ω c t+φ) where L and R represent first and second intelligence signals, ω c t is a carrier frequency signal, and φ is arc tan {(L-R)/(1+L+R)} and comprising in combination: input means for receiving said signal and deriving therefrom an intermediate frequency signal; envelope detector means coupled to the input means for detecting the amplitude modulation on the intermediate frequency signal; first circuit means coupled to the input means for providing an output related to the phase of the received carrier signal; second circuit means coupled to the first circuit means for providing an output related to the phase of the unmodulated carrier signal; third circuit means coupled to the first and the second circuit means for providing a signal proportional to cos φ. synchronous detector means coupled to the output of the second circuit means for providing an output proportional to (L-R)cos φ; divider means coupled to the synchronous detector means and to the third circuit means for providing an output proportional to L-R; and matrix means for processing the L-R and L+R signals to provide separate L and R outputs.

Claim 8

An AM receiver for receiving compatible stereo signals having the form (1+L +R)cos(ω c t+φ) where L and R represent first and second intelligence signals, ω c t is a carrier frequency signal, and φ is arc tan {(L-R)/(1+L+R)} and comprising in combination: input means for receiving said signal and deriving therefrom an intermediate frequency signal; envelope detector means coupled to the input means for detecting the amplitude modulation on the intermediate frequency signal; first circuit means coupled to the input means for providing an output related to the phase of the received carrier signal; second circuit means coupled to the first circuit means for providing an output related to the phase of the unmodulated carrier signal; third circuit means coupled to the first and the second circuit means for providing a signal proportional to cos φ. synchronous detector means coupled to the output of the second circuit means for providing an output proportional to (L-R)cos φ; divider means coupled to the synchronous detector means and to the third circuit means for providing an output proportional to L-R; and matrix means for processing the L-R and L+R signals to provide separate L and R outputs.

Claim 9

An AM receiver according to claim 5 wherein the first circuit means comprises a limiter circuit for removing amplitude modulation and providing a signal proportional to cos(ω c t+φ).

Claim 10

An AM receiver according to claim 5 wherein the second circuit means comprises a phase locked loop.

Claim 11

A receiver for receiving compatible AM stereo signals having the form (1+L+R)cos(ω c t+φ) where L and R represent first and second intelligence signals, ω c t is a carrier frequency signal, and φ is arc tan {(L-R)/ (1+L+R)} and comprising in combination: input means for receiving said AM stereo signal and deriving therefrom an intermediate frequency signal; first circuit means coupled to the input means for generating a first intermediate signal proportional in amplitude to the amplitude modulation in said received AM stereo signal; second circuit means coupled to the input means for generating a second intermediate signal proportional to (L-R)cos φ; third circuit means for generating a third intermediate signal proportional to cos φ; means for dividing the second intermediate signal by the third intermediate signal; and matrix means for processing the output of the divider means with the first intermediate signal to provide separate outputs proportional to L and R.

Claim 12

A receiver for receiving compatible AM stereo signals having the form (1+L+R)cos(ω c t+φ) where L and R represent first and second intelligence signals, ω c t is a carrier frequency signal, and φ is arc tan {(L-R)/ (1+L+R)} and comprising in combination: input means for receiving said AM stereo signal and deriving therefrom an intermediate frequency signal; first circuit means coupled to the input means for generating a first intermediate signal proportional in amplitude to the amplitude modulation in said received AM stereo signal; second circuit means coupled to the input means for generating a second intermediate signal proportional to (L-R)cos φ; third circuit means for generating a third intermediate signal proportional to cos φ; means for dividing the second intermediate signal by the third intermediate signal; and matrix means for processing the output of the divider means with the first intermediate signal to provide separate outputs proportional to L and R.

Claim 13

A receiver according to claim 8 wherein the input means comprises antenna means and means for selecting and mixing the received signal to provide a corresponding intermediate frequency signal.

Claim 14

A receiver according to claim 8 wherein the first circuit means comprises envelope detector means.

Claim 15

A receiver according to claim 8 wherein the second circuit means comprises synchronous detector means.

Claim 16

A receiver according to claim 8 wherein the third circuit means comprises a phase locked loop and a multiplier.

Claim 17

A receiver for receiving a broadcast carrier wave which is amplitude modulated with signal information proportional to the sum of first (A) and second (B) intelligence signals, and which is phase modulated with a signal proportional to an angle φ having the form φ= arc tan {c 1 (A-B)/(C 2 +A+B)}where C 1 and C 2 are constants, the receiver comprising in combination: input means for receiving and amplifying the broadcast carrier wave; means coupled to the input means for translating the broadcast carrier wave to one of an intermediate frequency; envelope detector means coupled to the translating means for providing a sum signal proportional to the amplitude modulation in the received AM stereo signal; synchronous detector means coupled to the translating means for providing a first signal proportional to (A-B) cos φ; corrector means for providing a second signal proportional to cos φ. means for dividing the first signal by the second signal; and matrix means for processing the outputs of the divider means and the envelope detector means to provide separate outputs proportional to A and B.

Claim 18

A receiver for receiving a broadcast carrier wave which is amplitude modulated with signal information proportional to the sum of first (A) and second (B) intelligence signals, and which is phase modulated with a signal proportional to an angle φ having the form φ= arc tan {c 1 (A-B)/(C 2 +A+B)}where C 1 and C 2 are constants, the receiver comprising in combination: input means for receiving and amplifying the broadcast carrier wave; means coupled to the input means for translating the broadcast carrier wave to one of an intermediate frequency; envelope detector means coupled to the translating means for providing a sum signal proportional to the amplitude modulation in the received AM stereo signal; synchronous detector means coupled to the translating means for providing a first signal proportional to (A-B) cos φ; corrector means for providing a second signal proportional to cos φ. means for dividing the first signal by the second signal; and matrix means for processing the outputs of the divider means and the envelope detector means to provide separate outputs proportional to A and B.

Claim 19

A receiver for receiving compatible AM stereo signals having the form (1+L+R)cos(ω c t+φ) were L and R represent first and second intelligence signals, ω c t is a carrier frequency signals, and φ is arc tan {(L-R)/ (1+L+R)} comprising: input means for receiving said signal and deriving therefrom an intermediate frequency signal; first circuit means coupled to the input means for deriving the sum signal directly from the amplitude modulation of the intermediate frequency signal; second circuit means coupled to the input means for deriving a signal proportional to (L-R)cos φ; third circuit means for deriving a cos φ correction factor for the difference signal; divider means for dividing the output of the second circuit means by the output of the third circuit means to provide the difference signal; and means for matrixing the sum and difference signals to provide L and R outputs.

Claim 20

A receiver for receiving compatible AM stereo signals having the form (1+L+R)cos(ω c t+φ) were L and R represent first and second intelligence signals, ω c t is a carrier frequency signals, and φ is arc tan {(L-R)/ (1+L+R)} comprising: input means for receiving said signal and deriving therefrom an intermediate frequency signal; first circuit means coupled to the input means for deriving the sum signal directly from the amplitude modulation of the intermediate frequency signal; second circuit means coupled to the input means for deriving a signal proportional to (L-R)cos φ; third circuit means for deriving a cos φ correction factor for the difference signal; divider means for dividing the output of the second circuit means by the output of the third circuit means to provide the difference signal; and means for matrixing the sum and difference signals to provide L and R outputs.

Claim 21

A receiver according to claim 14 wherein the first circuit means comprises an envelope detector, and the second circuit means comprises a synchronous detector and the third circuit means comprises limiter means, phase locked loop means and cosine phase detector means.