Equalizing and Main Station Repeaters

The equalizer remote‐control system performs the role of a master control for the adjustable equalizers in the lines of an L∼4 system. A control center located at an attended main station repeater may have jurisdiction over several hundred equalizers, some of which may be as distant as 800 miles. The required equalizer adjustments are determined from the relative powers of signals received from remotely controlled test oscillators at the equalizing locations. When necessary, the equalizers are remotely adjusted in discrete steps by means of commands sent out by the control center. Memory circuits associated with the equalizer networks maintain the network gain settings between adjustments. At each distant main station in a control system, a loop‐back unit provides decoding and switching that control equalizers at the location and complete far‐end looping paths to the lines to be equalized or checked. The looping paths pass the commands used to address the equalizing repeaters, which are located between the main station repeaters. The control system also comprises part of a fault‐location scheme, which includes a monitoring oscillator at each repeater.

show abstract

Optimal Equalization of Wideband Coaxial Cable Channels Using “Bump” Equalizers

Cho¹

1972

Bell System Technical Journal

View full text Add to dashboard Cite

Two methods are described for the optimal equalization of a channel with “Bump” Equalizers composed of several adjustable‐gain Bode Networks. The first method is a general one and applies a steepest descent algorithm which minimizes the total mean‐squared error (MSE) of the equalized channel. It requires continuous gradient information on the error‐gain relationship in order to determine exactly the optimum equalizer adjustments and involves a relatively complicated procedure to calculate the gradient. However, the second method, which also applies a steepest descent algorithm, develops the necessary gradient information with knowledge of the error signal only at selected frequencies across the bandwidth occupied by the channel. Under idealized assumptions, it is shown that the gradients obtained by the second method are exact. When the assumptions do not apply exactly, it is shown by computer simulation that the difference between the gradients obtained by the two methods is very small. A significant potential advantage of the second method lies in the hardware realization which only requires the measurement of the channel error at 2M‐1 frequencies at the equalizing station (where M is the number of Bode Networks in the equalizer). From these frequency domain errors, the gradients can be generated as real‐time signals and applied to the appropriate adjustable elements to obtain the optimum gain settings for minimum MSE.

show abstract

scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.

Contact Info

hi@scite.ai

10624 S. Eastern Ave., Ste. A-614

Henderson, NV 89052, USA

Blog Terms and Conditions API Terms Privacy Policy Contact Cookie Preferences Do Not Sell or Share My Personal Information

Made with 💙 for researchers

Part of the Research Solutions Family.

Equalizing and Main Station Repeaters

Cited by 6 publications

References 8 publications

The L-4 Coaxial System

The L-4 Coaxial System

The Equalizer Remote-Control System

Optimal Equalization of Wideband Coaxial Cable Channels Using “Bump” Equalizers

Contact Info

Product

Resources

About