Ring signal discriminator
First Claim
1. A ring signal and dial pulse detector for detecting and discriminating among normal ringing signals, call forward reminder ringing signals, and rotary dial pulses on a telephone line and comprising:
- a capacitor for blocking D.C. voltages on said telephone line;
optocoupler/isolator means connected across said telephone line and responsive to an input signal for providing a first output signal corresponding to, but electrically isolated from, said input signal;
low pass filter means for eliminating high frequency signals and noise transitions in said first output signal;
voltage comparator means for providing a second output signal responsive to the output voltage of said low pass filter means;
retriggerable timer means responsive to said second output signal for providing a third output signal which is retriggerable and which continues for a predetermined period after the last transition of a predetermined polarity of said second output signal; and
processor means responsive to the pulse width and repetition rate of said second and third output signals for providing a fourth output signal indicative of whether said input signal is a normal ringing signal, a call forward reminder ringing signal, or a rotary dial pulse.
13 Assignments
0 Petitions
Accused Products
Abstract
An improvement to automatic answering and call forwarding features used in telephone communications which allows a user to remotely activate, modify, and deactivate these features. The improvement describes a transformerless means for coupling signals to and from the telephone line without compromising the operation of the telephone line. The apparatus employs a microprocessor controller (11) with memory (12), a tone encoder (15), a tone decoder (14), a voice synthesizer (16), a timer (13), a cassette interface (17), an RS232C interface (20), a switching matrix (21), and a line interface (22). Audio, pulse dial, and tone signals are routed among the components and the telephone line (51) by the switching matrix (21) and line interface (22). The line interface (22) provides a transformerless means for coupling signals to and from the telephone line (51) and also analyzes the status of, and signals present on, the telephone line (51).
-
Citations
6 Claims
-
1. A ring signal and dial pulse detector for detecting and discriminating among normal ringing signals, call forward reminder ringing signals, and rotary dial pulses on a telephone line and comprising:
-
a capacitor for blocking D.C. voltages on said telephone line; optocoupler/isolator means connected across said telephone line and responsive to an input signal for providing a first output signal corresponding to, but electrically isolated from, said input signal; low pass filter means for eliminating high frequency signals and noise transitions in said first output signal; voltage comparator means for providing a second output signal responsive to the output voltage of said low pass filter means; retriggerable timer means responsive to said second output signal for providing a third output signal which is retriggerable and which continues for a predetermined period after the last transition of a predetermined polarity of said second output signal; and processor means responsive to the pulse width and repetition rate of said second and third output signals for providing a fourth output signal indicative of whether said input signal is a normal ringing signal, a call forward reminder ringing signal, or a rotary dial pulse. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A method for detecting and discriminating among normal ringing signals, call forward reminder ringing signals, and rotary dial pulses on a telephone line comprising:
-
blocking D.C. voltages on said telephone line; providing a first output signal corresponding to, but electrically isolated from, an input signal on said telephone line; providing a filtered signal by low pass filtering said first output signal to eliminate high frequency signals and noise transitions in said first output signal; providing a second output signal responsive to the output voltage level of said filtered signal; providing a third output signal which is responsive to transitions of a predetermined polarity in said second output signals and which continues for a predetermined period after the last transition of said predetermined polarity of said second output signal; and analyzing the pulse width and repetition rate of said second and third output signals for providing a fourth output signal indicative of whether said input signal is a normal ringing signal, a call forward reminder ringing signal, or a rotary dial pulse.
-
Specification