Telephone extension system utilizing power line carrier signals

In a power line telephone extension system for carrying electrical signals including dial pulses that define, make and break time intervals between a subscriber's telephone line of a conventional telephone communication system and the subscriber's extension telephone over available electric power wires, wherein there is a master location including master linking circuits for processing the signals, electrically coupled between the subscriber's telephone line and power wires, and an extension location along said power wires including an extension telephone and extension linking circuits for processing the signals, electrically coupled between the extension telephone and power wires, the improvement comprising,

• (a) means at the master location for detecting the edges of dial signal pulses received from the extension location and a monostable multivibrator set to operate in its unstable state for a predetermined time interval, and
• (b) means for imposing the monostable multivibrator output dial pulses of predetermined time interval on the telephone line, wherein
• (c) both the leading and trailing edges of the dial pulses are detected,
• (d) the leading edges trigger means for generating pulses shorter than the break interval between the ideal make interval,
• (e) the trailing edges trigger means for generating pulses longer than the break interval between the ideal make interval,
• (f) means are provided for producing pulses coincident with said shorter and longer pulses and
• (g) means are provided for applying said coincident pulses to said monostable multivibrator.

A power line telephone extension system for carrying electrical signals between a subscriber's telephone line of a conventional telephone communication system and the subscriber's conventional extension telephone over available electric power wires, comprising:

• (a) a master location including master linking circuits for processing the signals, electrically coupled between the subscriber's telephone line and power wires,
• (b) an extension location along said power wires including said conventional extension telephone and extension linking circuits for processing the signals, electrically coupled between the extension telephone and power wires,
• (c) the electrical signals include an extension telephone off-cradle signal originating at the extension telephone,
• (d) means are provided at the master location for detecting the edges of said cradle-off signal and producing a signal level representative thereof,
• (e) switching means are provided coupling the master linking circuits to the telephone line, said switching emans being controlled by said signal level representative of cradle-off, and
• (f) means at said extension location for generating dial pulses, and
• (g) means at the master location for detecting both the leading and trailing edges of the dial pulses, and wherein:
• (i) the leading edges trigger means for generating pulses shorter than the break interval between said interval,
• (ii) the trailing edges trigger means for generating pulses longer than said break interval between said interval,
• (iii) means are provided for producing pulses coincident with said shorter and longer pulses, and
• (iv) means are provided for applying said coincident pulses to said monostable multivibrator.

In a power line telephone extension system for carrying electrical signals including ring signals between a subscriber's telephone line of a conventional telephone communication system and the subscriber's extension telephone over available electric power wires, wherein there is a master location including master linking circuits for processing the signals, electrically coupled between the subscriber's telephone line and power wires and an extension location along said power wires including an extension telephone an extension ringer and extension linking circuits for processing the signals, electrically coupled between the extension telephone and power wires, the improvement comprising,

• (a) at the master location a master transmitter generates and transmits master carrier frequency to the extension location and said ring signals are detected in a ring detector circuit and turn on the master transmitter during the interval of each ring signal,
• (b) all signals carried to the extension location from the master location are carried by a master carrier frequency,
• (c) means at the extension location for detecting the occurrence of the master carrier frequency originating from the master transmitter,
• (d) means responsive thereto for generating an oscillating signal substantially coincident with said occurrence, the frequency of said oscillating signal and the power thereof being suitable for driving the extension ringer, and
• (e) means for coupling said oscillating signal to the extension ringer.