Browse Prior Art Database

PRINCIPLE OF SENSING LINE VOLTAGE WITHIN THE MALC SYSTEM

IP.com Disclosure Number: IPCOM000005691D
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2001-Oct-26
Document File: 2 page(s) / 75K

Publishing Venue

Motorola

Related People

Patrick Clement: AUTHOR [+2]

Abstract

The MALC system (Motorola Advanced Line Card system) contains a low voltage borscht associated with two high voltage current amplifiers. The complete system works in aclosed loop Thus it is feeding the subscriber line with current and senses voltage at the 2-wire port.

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MOTOROLA Technical Developments Volume 7 October 1997

PRINCIPLE OF SENSING LINE VOLTAGE WITHIN THE MALC SYSTEM

by Patrick Clement and Robert Smith

   The MALC system (Motorola Advanced Line Card system) contains a low voltage borscht associated with two high voltage current amplifiers. The complete system works in aclosed loop Thus it is feeding the subscriber line with current and senses voltage at the 2-wire port.

The proposed principle allows the AC and DC differential signals on the line to be sensed separately. It is also possible to control voltage levels on both wires and to sense and reject longitudinal currents.

   The realization of this principle is shown in FIG 1. ITIP and IRING are virtual grounds. Because of the longitudinal path closing the loop, the node LONG is also a virtual ground. Therefore by means of the input dividing network it is possible to collect on the DC port the complete differential signal divided by a large ratio l/rDc. Note that although it is called DC port the AC component is going to be eliminated further. CI, and C12 are chosen such that only differential AC signals divided by a smaller ratio l/rAo are collected at the AC port with a gain error lower than 0.05dB in the voice band. Thus no special matching is required between C,, and C12. The dividing ratios are given by:

RI3

rDc = R,, + RI> + RIZ

1

9

Rr2 + RU )

with the assumption that RI1 = Rs, RIG = RIG, RIG = RIG and RIG = RIS.

The AC differential signal is much small than t...