Tone detector with constant detection response time

Claim 2

A detector for detecting any one of the particular sinusoidal tone frequency signals in a range of sinusoidal tone frequency signals and having a constant detection time period, said detector including in combination; converter means being operative in response to said particular sinusoidal tone frequency signals exceeding a predetermined threshold to develop square wave signaLs having substantially a 50 percent duty cycle, integration means coupled to said converter means and responsive to the square wave signals coupled thereto to develop an integration voltage, said integration voltage reaching a predetermined amplitude level in response to said square wave signals in said constant detection time period, and switch means coupled to said integration means and responsive to said integration voltage reaching said predetermined amplitude level to develop a detection signal.

Claim 3

The detector of claim 1 wherein said converter means includes, phase splitter means for receiving said particular sinusoidal tone freuqency signals, said phase splitter means being operative to develop first tone frequency signals, and second tone frequency signals substantially 180* out of phase with said first tone frequency signals, multivibrator means having first and second states coupled to said phase splitter means and responsive to said first and second tone frequency signals exceeding a predetermined amplitude to switch between said first and second states and develop said square wave signals.

Claim 4

A detector for detecting any one of the particular tone frequency signals in a range of signals and having a constant detection time period, said detector including in combination; first circuit means for receiving said particular tone frequency signals and having first and second outputs, said first circuit means being operative to develop said first tone frequency signals having a first phase at said first output and second tone frequency signals having a second phase at said second output, second circuit means having a first and second state coupled to said first and second output of said first circuit means, said second circuit means being responsive to said signals from said first and second outputs to switch between said first and second states and develop a square wave signal train having substantially a 50 percent duty cycle, integration means coupled to said second circuit means and responsive to the square wave signals coupled thereto to develop an integration voltage, said integration voltage reaching a predetermined amplitude level in said constant detection time period, and switch means coupled to said integration means and responsive to said integration voltage reaching said predetermined amplitude level to develop a detection signal.

Claim 5

A detector for detecting any one of the particular tone frequency signals in a range of signals and having a constant detection time period, said detector including in combination; first circuit means for receiving said particular tone frequency signals and having first and second outputs, said first circuit means being operative to develop said first tone frequency signals having a first phase at said first output and second tone frequency signals having a second phase at said second output, second circuit means having a first and second state coupled to said first and second output of said first circuit means, said second circuit means being responsive to said signals from said first and second outputs to switch between said first and second states and develop a square wave signal train having substantially a 50 percent duty cycle, integration means coupled to said second circuit means and responsive to the square wave signals coupled thereto to develop an integration voltage, said integration voltage reaching a predetermined amplitude level in said constant detection time period, and switch means coupled to said integration means and responsive to said integration voltage reaching said predetermined amplitude level to develop a detection signal.

Claim 6

The detector of claim 3 wherein said first circuit means includes phase splitter means said phase splitter means being operative to develop said first and second tone frequency signals, said second tone frequency signals being substantially 180* out of phase with said first tone frequency signals, said first tone frequency signals having positive and negative half cycles of substantially equal period, said second circuit means including third circuit means responsive to one of said positive and negative half cycles coupled thereto from said first output to switch to said first state, and fourth circuit means responsive to one of said positive and negative half cycles coupled thereto from said second output to switch to said second state.

Claim 7

The detector of claim 4 wherein said second circuit means includes bistable multivibrator means coupled to said phase splitter means first and second outputs, said bistable multivibrator means being responsive to said signals from said first output to switch to said first state and responsive to said signals from said second output to switch to said second state.

Claim 8

The detector of claim 5 wherein said second circuit means further includes bias means coupling said phase splitter means first and second outputs to said bistable multivibrator means, third and fourth circuit means said bias means biasing said bistable multivibrator means to switch states in response to one of said positive and negative half cycles of said particular tone frequency signals coupled thereto.

Claim 9

The detector of claim 6 wherein said second circuit means furTher includes reset circuit means being operative in response to said bistable multivibrator means remaining in said first state for a predetermined period of time to reset said bistable multivibrator means to said second state.

Claim 10

The detector of claim 7 wherein said predetermined period of time is greater than the period of one half cycle of the lowest particular tone frequency signals in said range of signals.

Claim 11

The detector of claim 8 wherein said switch means includes differential amplifier means having a first input, bias means coupled to said first input for coupling a bias voltage thereto equal to said integration voltage predetermined amplitude level, and second input means coupled to said integration means for receiving said integration voltage therefrom, said differential amplifier means being operative in response to said integration voltage reaching said predetermined amplitude level to develop said detection signal.

Claim 12

The detector of claim 9 wherein said bistable multivibrator means third circuit means includes first transistor means having base, said fourth circuit means includes second transistor means having base, emitter and collector electrodes, emitter and collector electrodes, said first and second transistor means being coupled together to form said bistable multivibrator means.

Claim 13

The detector of claim 10 wherein said reset means includes second integration means coupled to the bistable multivibrator means first transistor means and operative to develop a second integration voltage in response to said bistable multivibrator means remaining in said first state, and switching means coupled to said integration means and said bistable multivibrator means second transistor means and responsive to said second integration voltage exceeding a predetermined amplitude to switch said bistable multivibrator means to said second state.

Claim 14

The detector of claim 11 wherein said switch means further includes amplifier means coupled to said differential amplifier means, for amplifying said detection signal.

Claim 15

A detector for detecting any one of the particular tone frequency signals in a range of signals and having a constant detection time period, said detector including in combination; phase splitter means for receiving said particular tone frequency signals, said phase splitter means being operative to develop first tone frequency signals and second tone frequency signals substantially 180* out of phase with said first tone frequency signals, multivibrator means being operable to first and second states, said multivibrator means including bias means coupling said phase splitter means to said multivibrator means, said bias means biasing said multivibrator means to switch states in response to said first and second tone frequency signals coupled thereto, said multivibrator means being responsive to said first and second tone frequency signals coupled thereto to switch between said first and second states and develop a square wave signal train having substantially a 50 percent duty cycle, integration means coupled to said multivibrator means and responsive to the square wave signals coupled thereto to develop an integration voltage, said integration voltage reaching a predetermined amplitude level in said constant duration time period, differential amplifier means having a first input, bias means coupled to said first input for coupling a bias voltage thereto equal to said integration voltage predetermined amplitude level, and second input means coupled to said integration means for receiving said integration voltage therefrom, said differential amplifier means being operative in response to said integration voltage reaching said predetermined amplitude level to develop said detection signal, and reset circuit means being operative in response to said multivibrator means remaining in said first state for a predetermined period of time to reset said multivibrator means to said second state.

Claim 16

A detector for detecting any one of the particular tone frequency signals in a range of signals and having a constant detection time period, said detector including in combination; phase splitter means for receiving said particular tone frequency signals, said phase splitter means being operative to develop first tone frequency signals and second tone frequency signals substantially 180* out of phase with said first tone frequency signals, multivibrator means being operable to first and second states, said multivibrator means including bias means coupling said phase splitter means to said multivibrator means, said bias means biasing said multivibrator means to switch states in response to said first and second tone frequency signals coupled thereto, said multivibrator means being responsive to said first and second tone frequency signals coupled thereto to switch between said first and second states and develop a square wave signal train having substantially a 50 percent duty cycle, integration means coupled to said multivibrator means and responsive to the square wave signals coupled thereto to develop an integration voltage, said integration voltage reaching a predetermined amplitude level in said constant duration time period, differential amplifier means having a first input, bias means coupled to said first input for coupling a bias voltage thereto equal to said integration voltage predetermined amplitude level, and second input means coupled to said integration means for receiving said integration voltage therefrom, said differential amplifier means being operative in response to said integration voltage reaching said predetermined amplitude level to develop said detection signal, and reset circuit means being operative in response to said multivibrator means remaining in said first state for a predetermined period of time to reset said multivibrator means to said second state.