Automatic cable equalizer circuit

• US 4,151,490 A
• Filed: 06/29/1977
• Issued: 04/24/1979
• Est. Priority Date: 03/21/1977
• Status: Expired due to Term

• Current Assignee: RCA Corporation (General Electric Company)
• Original Assignee: RCA Corporation (General Electric Company)
• Inventors: Bazin, Lucas J.
• Primary Examiner(s): Martin, John C.
• Application Number:
  US05/811,291
• Time in Patent Office: 664 Days
• Field of Search: 358/35, 358/38, 358/86, 358/160, 358/188, 333/15, 333/16, 333/17 R, 333/18, 179/170 A, 325/308, 325/472, 328/162, 328/168
• US Class Current: 333/16
• CPC Class Codes: H04B 3/145 variable equalisers
• CPC Class Codes: H04N 7/102 Circuits therefor, e.g. noise reducers, equalisers, amplifiers H04N7/108 takes precedence

Abstract

A cable equalizer is provided for automatically compensating a signal for cable attenuation as the length of the cable is varied. The circuit detects changes in a reference signal that is inserted in the signal being transmitted over the cable. Any deviation of the reference signal from its normal state at the receiving end of the cable causes the addition of a correction signal to the signal being transmitted so as to compensate the signal for the cable attenuation.

Claims

1. A signal cable equalizer circuit for automatically compensating signals transmitted over a cable, said cable signals incurring amplitude and frequency response losses during said transmission, comprising:

means for including a reference signal having both low and high frequency components in said cable signals to be transmitted, said reference signal components exhibiting a relative difference in amplitude as a result of transmission losses;

signal summing means responsive to said cable signals for providing an output signal;

signal processing means coupled to said cable signals for developing a correction signal which is complementary to cable loss for all frequencies transmitted over said cable for a predetermined length of cable derived from said cable signals;

detector means coupled to said signal summing means for developing a control signal proportional to the relative amplitude difference between said low and high frequency reference signal components; and

multiplier means responsive to said correction signal and said control signal for coupling an amount of said correction signal as determined by said control signal to said signal summing means for restoring the amplitude of said output signal.

2. A signal cable equalizer circuit according to claim 1 including means coupled between the output of said signal summing means and the input of said signal processing means for coupling said output signal to said signal processing means to provide higher order correction signals to said multiplier means.