Telephone ringer counter

Claim 2

A circuit for counting ringing devices connected to a communication loop comprising first means for generating a first frequency signal; second means for generating a second frequency signal; means for coupling said first and second frequency signals to said communication loop, each ringing device comprising a resonance circuit having a resonance frequency intermediate said first and second frequencies; means connected to said communication loop for detecting a resultant communication loop signal responsive to said coupled first and second frequency signals having first and second frequency components; means for separating said resultant first frequency component from said resultant second frequency component; means connected to said separating means for producing a third signal corresponding to said separated first frequency component and for producing a fourth signal corresponding to said separated second frequency component; and means for subtracting said fourth signal from said third signal, the output of said subtracting means corresponding to the number of ringing devices connected to said communication loop.

Claim 3

A circuit for counting ringing devices connected to a communication loop comprising first means for generating a first frequency signal; second means for generating a second frequency signal; means for coupling said first and second frequency signals to said communication loop, each ringing device comprising a resonance circuit having a resonance frequency intermediate said first and second frequencies; means connected to said communication loop for detecting a resultant communication loop signal responsive to said coupled first and second frequency signals having first and second frequency components; means for separating said resultant first frequency component from said resultant second frequency component; means connected to said separating means for producing a third signal corresponding to said separated first frequency component and for producing a fourth signal corresponding to said separated second frequency component; and means for subtracting said fourth signal from said third signal, the output of said subtracting means corresponding to the number of ringing devices connected to said communication loop.

Claim 4

A circuit for counting ringing devices connected to a communication loop comprising first means for generating a first frequency signal; second means for generating a second frequency signal; means for coupling said first and second frequency signals to said communication loop, each ringing device comprising a resonance circuit having a resonance frequency intermediate said first and second frequencies; means connected to said communication loop for detecting a resultant communication loop signal responsive to said coupled first and second frequency signals having first and second frequency components; means for separating said resultant first frequency component from said resultant second frequency component; means connected to said separating means for producing a third signal corresponding to said separated first frequency component and for producing a fourth signal corresponding to said separated second frequency component; and means for subtracting said fourth signal from said third signal, the output of said subtracting means corresponding to the number of ringing devices connected to said communication loop.

Claim 5

A circuit for counting ringing devices connected to a communication loop according to claim 1 wherein said separating means comprises a first filter for passing only said first frequency component and a second filter for passing only said second frequency component.

Claim 6

A circuit for counting ringing devices connected to a communication loop according to claim 2 wherein said third signal producing means comprises means connected to said first filter for producing a DC signal corresponding to said separated first frequency component and said fourth signal producing means comprises means connected to said second filter for producing a DC signal corresponding to said separated second frequency component.

Claim 7

A circuit for counting ringing devices connected to a communication loop according to claim 3 wherein said subtracting means comprises a difference amplifier having a first input connected to said third signal producing means and a second input connected to said fourth signal producing means, said amplifier being operative to produce an output signal proportional to the difference between said third and fourth signals.

Claim 8

A circuit for counting ringing devices connected to a communication loop according to claim 4 wherein said coupling means comprises means connected to said first and second generating means for summing said first and second frequency signals.

Claim 9

A circuit for counting the number of ringing devIces connected to a telephone subscriber loop wherein each ringing device comprises a series resonance circuit having a fixed resonant frequency comprising means for generating first and second frequency signals, said first frequency being below said resonant frequency and said second frequency being above said resonant frequency; means for applying said first and second frequency signals to said subscriber loop; means connected to said subscriber loop responsive to said applied first and second frequency signals for sensing the resultant loop current, said sensed loop current including said first and second frequency components; a first bandpass filter connected to said sensing means for passing said first frequency component; a second bandpass filter connected to said sensing means for passing said second frequency component; means connected to said first bandpass filter for converting said passed first frequency component to a first DC signal proportional thereto; means connected to said second bandpass filter for converting said passed second frequency component to a second DC signal proportional thereto; and means for subtracting said second DC signal from said first DC signal, the output of said subtracting means being proportional to the number of ringing devices connected to said subscriber loop.

Claim 10

A circuit for counting the number of ringing devIces connected to a telephone subscriber loop wherein each ringing device comprises a series resonance circuit having a fixed resonant frequency comprising means for generating first and second frequency signals, said first frequency being below said resonant frequency and said second frequency being above said resonant frequency; means for applying said first and second frequency signals to said subscriber loop; means connected to said subscriber loop responsive to said applied first and second frequency signals for sensing the resultant loop current, said sensed loop current including said first and second frequency components; a first bandpass filter connected to said sensing means for passing said first frequency component; a second bandpass filter connected to said sensing means for passing said second frequency component; means connected to said first bandpass filter for converting said passed first frequency component to a first DC signal proportional thereto; means connected to said second bandpass filter for converting said passed second frequency component to a second DC signal proportional thereto; and means for subtracting said second DC signal from said first DC signal, the output of said subtracting means being proportional to the number of ringing devices connected to said subscriber loop.

Claim 11

A circuit for counting the number of ringing devices connected to a communication loop wherein each ringing device comprises a series resonance circuit having a fixed resonant frequency, said circuit comprising means for generating a below-resonance frequency signal; means for generating a first above-resonance frequency signal; means for generating a second above-resonance frequency signal; means for applying said below-resonance and said first and second above-resonance frequency signals to said communication loop; means connected to said loop for detecting a resultant signal responsive to said applied signals having a below-resonance frequency component and first and second above-resonance frequency components; means for separating said below-resonance frequency component and said first and second above-resonance frequency components; means responsive to said separated below-resonance component for producing a first signal corresponding to said separated below-resonance frequency component; means for producing a second signal corresponding to said separated first above-resonance frequency component; means for producing a third signal corresponding to said separated second above-resonance frequency component; means for comparing said third signal with a predetermined reference signal; means responsive to said third signal exceeding said predetermined reference signal for subtracting said second signal from said first signal; and means responsive to said third signal being equal to or less than said predetermined level signal for subtracting said third signal from said first signal.

Claim 12

A circuit for counting the number of ringing devices connected to a communication loop wherein each ringing device comprises a series resonance circuit having a fixed resonant frequency, said circuit comprising means for generating a below-resonance frequency signal; means for generating a first above-resonance frequency signal; means for generating a second above-resonance frequency signal; means for applying said below-resonance and said first and second above-resonance frequency signals to said communication loop; means connected to said loop for detecting a resultant signal responsive to said applied signals having a below-resonance frequency component and first and second above-resonance frequency components; means for separating said below-resonance frequency component and said first and second above-resonance frequency components; means responsive to said separated below-resonance component for producing a first signal corresponding to said separated below-resonance frequency component; means for producing a second signal corresponding to said separated first above-resonance frequency component; means for producing a third signal corresponding to said separated second above-resonance frequency component; means for comparing said third signal with a predetermined reference signal; means responsive to said third signal exceeding said predetermined reference signal for subtracting said second signal from said first signal; and means responsive to said third signal being equal to or less than said predetermined level signal for subtracting said third signal from said first signal.