Telephone ring detector circuit
First Claim
1. A telephone ring detector system which is responsive to a ringing signal received over a telephone line in bursts individually having a predetermined minimum number of cycles and said bursts being separated by a first predetermined time interval, and which is unresponsive to dialing pulses received over the telephone line in trains individually having a predetermined maximum number of pulses less than said minimum number of cycles of each burst of the ringing signal and separated by a second predetermined time interval, said system comprising:
- a counter;
first circuit means connected to said counter for introducing pulses to said counter so as to cause said counter to count from a reference count;
input circuit means connected to the telephone line and to the first circuit means and responsive to the ring signal and dialing pulses thereon to cause said first circuit means to introduce pulses to said counter to cause said counter to count from said reference count;
reset circuit means connected to said counter to reset said counter to said reference count during the first and second predetermined time intervals; and
output terminal means connected to said counter at which an output signal is produced only when said counter achieves a predetermined count corresponding to said predetermined minimum number of cycles of each of said bursts of ringing signal.
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Accused Products
Abstract
A telephone ring detector circuit is provided which finds particular utility in telephone answering systems. The detector circuit responds only to ring signals on the telephone line to activate the system, and it is unresponsive to dialing pulses, or other signals, that may be present on the telephone line. The detector circuit of the invention distinguishes the ring signals from the other signals on the telephone line by counting the number of pulses present on the telephone line for the various signals and providing a ring detect output only when the number of pulses is in excess, for example, of the pulses which form the trains of the dialing signal.
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Citations
7 Claims
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1. A telephone ring detector system which is responsive to a ringing signal received over a telephone line in bursts individually having a predetermined minimum number of cycles and said bursts being separated by a first predetermined time interval, and which is unresponsive to dialing pulses received over the telephone line in trains individually having a predetermined maximum number of pulses less than said minimum number of cycles of each burst of the ringing signal and separated by a second predetermined time interval, said system comprising:
- a counter;
first circuit means connected to said counter for introducing pulses to said counter so as to cause said counter to count from a reference count;
input circuit means connected to the telephone line and to the first circuit means and responsive to the ring signal and dialing pulses thereon to cause said first circuit means to introduce pulses to said counter to cause said counter to count from said reference count;
reset circuit means connected to said counter to reset said counter to said reference count during the first and second predetermined time intervals; and
output terminal means connected to said counter at which an output signal is produced only when said counter achieves a predetermined count corresponding to said predetermined minimum number of cycles of each of said bursts of ringing signal. - View Dependent Claims (2, 3, 4)
- a counter;
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5. A detector system which is responsive to a first signal received in bursts individually having a predetermined minimum number of cycles and said bursts being separated by a first predetermined time interval, and which is unresponsive to a second signal received in bursts individually having a predetermined maximum number of cycles less than said minimum number of cycles of each burst of said first signal and separated by a second predetermined time interval, said system comprising:
- a counter;
first circuit means connected to said counter for introducing pulses to said counter so as to cause said counter to count from a reference count;
input circuit means connected to said first circuit means and responsive to the first and second signals to cause said first circuit means to introduce pulses to said counter to cause said counter to count from said reference count;
reset circuit means connected to said counter to reset said counter to said reference count during the first and second predetermined time intervals; and
output terminal means connected to said counter at which an output signal is produced only when said counter achieves a predetermined count corresponding to said predetermined minimum number of cycles of each of said bursts of said first signal. - View Dependent Claims (6, 7)
- a counter;
Specification