Telephone network protective coupler

Details Telephone network protective coupler Telephone network protective coupler

1977-04-07

1979-04-03

Claffy, Kathleen H.

Amplifiers

Signal feedback

Combined with control of bias voltage of signal amplifier

179 1A, 179 81B, 330138, H04B 308

Patent

active

041479009

ABSTRACT:
A telephone network protective coupler for connecting terminal equipment to a telephone central office by means of a telephone line. The coupler includes two hybrid circuits which are interconnected to form a transmitting path and a receiving path. A power limiter in the transmitting path can be programmed remotely by selection of an external programming resistor without the direct introduction of noise into the transmitting path. The programming feature permits the gain of the transmitting portion of the device to be varied in steps from 0 to -12dB., and the maximum power output to be varied correspondingly in steps from 0 to -12 dBm. in order to arrive at an optimum signal power level of -12dBm. at the central office. The power limiter includes a controller gain amplifier for varying the attenuation of the transmitting path to a.c. signals, a remotely adjustable attenuator connected to a d.c. voltage source, and a gain control circuit connected to the amplifier and to the attenuator and responsive to adjustment of the attenuator for controling the gain of the amplifier. The power limiter further includes a rectifier for rectifying the a.c. signals after passage through the amplifier, and a maximum power control circuit connected to the rectifier and the attenuator and responsive to the adjustment of the attenuator for keeping the ratio of the amplitude of the rectified a.c. signals to the output voltage of the attenuator less than or substantially equal to a fixed constant.

REFERENCES:
patent: 3558830 (1971-01-01), Bender
patent: 3781481 (1973-12-01), Shaffer et al.
patent: 3903378 (1975-09-01), Lee et al.
patent: 3914560 (1975-10-01), Greene
patent: 3925624 (1975-12-01), Earle et al.
patent: 3989902 (1976-11-01), Cowpland
patent: 4024346 (1977-05-01), McDermott

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