GB2146191A - Frequency division transmission equipment - Google Patents

Frequency division transmission equipment Download PDF

Info

Publication number
GB2146191A
GB2146191A GB08421079A GB8421079A GB2146191A GB 2146191 A GB2146191 A GB 2146191A GB 08421079 A GB08421079 A GB 08421079A GB 8421079 A GB8421079 A GB 8421079A GB 2146191 A GB2146191 A GB 2146191A
Authority
GB
United Kingdom
Prior art keywords
digitally
frequency division
transmission equipment
control
signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08421079A
Other versions
GB8421079D0 (en
Inventor
Derek George Emery
Mark Edward Phillips
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co PLC
Original Assignee
General Electric Co PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co PLC filed Critical General Electric Co PLC
Publication of GB8421079D0 publication Critical patent/GB8421079D0/en
Publication of GB2146191A publication Critical patent/GB2146191A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/005—Control by a pilot signal
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G1/00—Details of arrangements for controlling amplification
    • H03G1/0005—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal
    • H03G1/0088—Circuits characterised by the type of controlling devices operated by a controlling current or voltage signal using discontinuously variable devices, e.g. switch-operated
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/001—Digital control of analog signals

Landscapes

  • Time-Division Multiplex Systems (AREA)

Abstract

A control arrangement comprises respective digitally controllable attenuator in each of the signal channels and digital signal processor 7 arranged to control the attenuation introduced by each of the attenuators in dependence upon stored digitally coded instructions such as from an EPROM 8. Channel attenuation is provided using capacitor ratios effected by a switched capacitor array under control of the microprocessor, each switched value being stored in the EPROM 8. Channel attenuation is provided using capacitor ratios effected by a switched capacitor array under control of the microprocessor, each switched value being stored in the EPROM 8. Pilot signal monitoring 17 and Amplifier adjustment by voltage control is a further microprocessor function. <IMAGE>

Description

SPECIFICATION Frequency division multiplex transmission equipment The present invention relates to frequency division multiplex transmission equipment.
According to one aspect of the present invention in frequency division multiplex transmission equipment a control arrangement comprises respective digitally controllable attenuator means in each of a plurality of signal channels, and digital signal processor means arranged to control the attenuation introduced by each of said attenuator means in dependence upon stored digitally coded instructions.
Preferably said attenuator means comprises a switch-capacitor arrangement, while said digital signal processor means may comprise a microprocessor.
According to another aspect, of the present invention in frequency division multiplex transmission equipment in which one or more signalling tones may be transmitted or received over any one of a plurality of channels a control arrangement comprises means periodically digitally to encode signalling values received on or to be transmitted on each of said plurality of channels, digital data storage means and digital signal processor means responsive to said digitally coded signalling values to provide output signals in dependence upon said values and digitally coded information held in said storage means.
The digital coded information held in said storage means may include predetermined threshold level and/or timing information.
The means periodically to encode said signalling values also may be arranged periodically to encode signals derived from monitor ing points in said equipment, for example for comparison in said digital signal processor means with predetermined values or ranges of values held in said storage means.
According to another aspect of the present invention in frequency division multiplex transmission equipment an arrangement for amplifying signals including a pilot signal comprises a controllable-gain amplifier, means to derive a digitally-coded signal representing the amplitude of said pilot signal at the output of said amplifier, digital data storage means, and digital signal processor means responsive to said digitally-coded amplitude signal and to digitally coded information held in said data storage means to provide a gain-control signal for said amplifier.
Frequency division multiplex transmission equipment including a control arrangement in accordance with the present invention will now be described by way of example with reference to the accompanying drawing, which shows part of the equipment schematically.
Referring to the drawing the equipment forms part of a frequency division multiplex transmission system in which voice frequency signals in, say, twelve 4KHz telephone channels are combined or "stacked" in the frequency domain by modulating each of these voice frequency signals into a respective one of a set of carrier signals spaced at 4KHz intervals to form a "group" occupying a frequency band extending from 60KHz to 108KHz. A number of these groups, for example five groups, may be stacked again in the frequency domain to form a super-group before transmission from one station of the system to another, for example over a transmission line or a radio link.
The voice frequency signals in a channel may comprise either speech signals, in a frequency band from 300Hz to 3400Hz, for transmission over the system from one telephone subscriber to another, or bursts of a signalling tone at a frequency of, say, 3825Hz.
When signalling information is to be transmitted pulses representing this information at a rate of, say, ten per second from exchange equipment (not shown) in respect of any one channel are applied over a respective path 1 to a respective signal conditioner circuit 2, while signalling information receiver over the transmission line or radio link in respect of any one channel is applied, in the form of bursts of signalling tone, over a respective path 3 to a respective full-wave rectifier and filter circuit 4. The outputs of up to six of the signal conditioner circuits 2 and six rectifier and filter cifcuits 4 may be connected to respective inputs of an analogue multiplexor 5, which is arranged to sample any signal voltage which is present at each input in turn at a repetition rate of, say, 1 KHz and apply the sample to an analogue-to-digital convertor circuit 6.
The digitised output signals from the circuit 6 are passed to a microprocessor 7 where, under the control of program information held in an erasable programmable read only memory, or EPROM, 8 the signals are shaped and retimed for application to respective tone modulators (not shown) by way of output paths 9 in respect of pulses to be transmitted, or to respective relay drivers (not shown) by way of output paths 10 in respect of received pulses.
One or more additional signal conditioner circuits 11 may be provided to apply signals from system monitoring points (not shown) to the multiplexer 5, and the microprocessor 7 may be arranged to provide appropriate output signals in response to these monitoring signals over output paths 1 2.
The microprocessor 7 may be provided with serial input/output interfaces 1 3 by which information may be exchanged with a handheld programming and collating unit (not shown). It will be appreciated that two micro processors 7 and associated circuits are required to monitor and control the twelve channels of a group.
Received group-plus-pilot signals on an input path 14 are arranged to be amplified by a variable-gain amplifier 1 5 the gain of which is controlled by one of the microprocessors 7, by way of a digital to analogue convertor circuit 16, in dependence upon the level of the pilot signal picked off by a pilot extraction circuit 17, so as to keep the level of that pilot signal at the output of the amplifier 1 5 to a preset level.
In dependence upon information held in the EPROM 8 control signals may be applied by each microprocessor 7 by way of a highway 1 8 to up to six digitally controlled attenuators (not shown) in respective speech signal channels. These attenuators may for example be switched capacitor attenuators.
The hand-held programming and collating unit may be arranged to set or to update digital code values held by the EPROM 8 which determine for example levels of attenuation required, or gain limits for the amplifier 1 5. Similarly information derived from the monitoring points for analysis, alarm indication and so on, may be retrieved from a number of groups by way of respective interfaces 13.

Claims (4)

1. Frequency division multiplex transmission equipment wherein a control arrangement comprises respective digitally controllable attenuator means in each of a plurality of signal channels, and digital signal processor means arranged to control the attenuation introduced by each of said attenuator means in dependence upon stored digitally coded instructions.
2. Frequency division multiplex transmission equipment in which one or more signalling tones may be transmitted or received over any one of a plurality of channels wherein a control arrangement comprises means periodically digitally to encode signalling values received on or to be transmitted on each of said plurality of channels, digital data storage means and digital signal processor means responsive to said digitally coded signalling values to provide output signals in dependence upon said values and digitally coded information held in said storage means.
3. Frequency division multiplex transmission equipment wherein an arrangement for amplifying signals including a pilot signal comprises a controllable-gain amplifier, means to derive a digitally-coded signal representing the amplitude of said pilot signal at the output of said amplifier, digital data storage means, and digital signal processor means responsive to said digitally-coded amplitude signal and to digitally coded information held in said data storage means to provide a gain-control signal for said amplifier.
4. Frequency division multiplex transmission equipment substantially as hereinbefore described with reference to the accompanying drawing.
GB08421079A 1983-08-19 1984-08-20 Frequency division transmission equipment Withdrawn GB2146191A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB838322440A GB8322440D0 (en) 1983-08-19 1983-08-19 Frequency division multiplex transmission equipment

Publications (2)

Publication Number Publication Date
GB8421079D0 GB8421079D0 (en) 1984-09-26
GB2146191A true GB2146191A (en) 1985-04-11

Family

ID=10547606

Family Applications (2)

Application Number Title Priority Date Filing Date
GB838322440A Pending GB8322440D0 (en) 1983-08-19 1983-08-19 Frequency division multiplex transmission equipment
GB08421079A Withdrawn GB2146191A (en) 1983-08-19 1984-08-20 Frequency division transmission equipment

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB838322440A Pending GB8322440D0 (en) 1983-08-19 1983-08-19 Frequency division multiplex transmission equipment

Country Status (1)

Country Link
GB (2) GB8322440D0 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989007366A1 (en) * 1988-02-02 1989-08-10 SIEMENS AKTIENGESELLSCHAFT öSTERREICH Circuit arrangement with adjustable active and/or passive components
EP0468507A1 (en) * 1990-07-27 1992-01-29 Kabushiki Kaisha Toshiba Automatic power control apparatus
FR2665988A1 (en) * 1990-08-14 1992-02-21 Cit Alcatel METHOD AND DEVICE FOR AUTOMATIC GAIN CONTROL OF A VARIABLE GAIN AMPLIFIER, AND THEIR APPLICATION TO THE GAIN CONTROL OF A TUNER, IN PARTICULAR FOR VIDEOCOMMUNICATION NETWORK.
WO1997002656A1 (en) * 1995-06-30 1997-01-23 Telefonaktiebolaget Lm Ericsson (Publ) Adaptive gain controller
EP0788265A3 (en) * 1996-01-31 1999-10-13 Victor Company Of Japan, Limited Synchronisation in multicarrier systems

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1161238A (en) * 1965-10-24 1969-08-13 Texas Instruments Inc Gain Control Circuit.
GB1239585A (en) * 1967-12-29 1971-07-21
GB1284160A (en) * 1969-09-04 1972-08-02 Texaco Development Corp Amplifier system
WO1980001632A1 (en) * 1979-02-01 1980-08-07 A Michel Signal processing system with multichannel electronic attenuator and stored controls
GB1596943A (en) * 1978-02-14 1981-09-03 Itt Ind Ltd Level control of digital signals
GB2106301A (en) * 1978-09-27 1983-04-07 Paramount Sound Systems Corp Method and system of controlling sound and effects devices by a film strip
GB2113029A (en) * 1981-12-31 1983-07-27 Rca Corp Digital gain control system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1161238A (en) * 1965-10-24 1969-08-13 Texas Instruments Inc Gain Control Circuit.
GB1239585A (en) * 1967-12-29 1971-07-21
GB1284160A (en) * 1969-09-04 1972-08-02 Texaco Development Corp Amplifier system
GB1596943A (en) * 1978-02-14 1981-09-03 Itt Ind Ltd Level control of digital signals
GB2106301A (en) * 1978-09-27 1983-04-07 Paramount Sound Systems Corp Method and system of controlling sound and effects devices by a film strip
WO1980001632A1 (en) * 1979-02-01 1980-08-07 A Michel Signal processing system with multichannel electronic attenuator and stored controls
GB2113029A (en) * 1981-12-31 1983-07-27 Rca Corp Digital gain control system

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1989007366A1 (en) * 1988-02-02 1989-08-10 SIEMENS AKTIENGESELLSCHAFT öSTERREICH Circuit arrangement with adjustable active and/or passive components
EP0380819A1 (en) * 1988-02-02 1990-08-08 Siemens Aktiengesellschaft Circuit with controllable active and/or passive elements
EP0468507A1 (en) * 1990-07-27 1992-01-29 Kabushiki Kaisha Toshiba Automatic power control apparatus
US5303268A (en) * 1990-07-27 1994-04-12 Kabushiki Kaisha Toshiba Automatic power control apparatus
FR2665988A1 (en) * 1990-08-14 1992-02-21 Cit Alcatel METHOD AND DEVICE FOR AUTOMATIC GAIN CONTROL OF A VARIABLE GAIN AMPLIFIER, AND THEIR APPLICATION TO THE GAIN CONTROL OF A TUNER, IN PARTICULAR FOR VIDEOCOMMUNICATION NETWORK.
EP0476302A1 (en) * 1990-08-14 1992-03-25 Alcatel Cit Method and device for automatic gain control of amplifier, and application for the gain control of a tuner, particularly for videocommunication networks
WO1997002656A1 (en) * 1995-06-30 1997-01-23 Telefonaktiebolaget Lm Ericsson (Publ) Adaptive gain controller
US5727031A (en) * 1995-06-30 1998-03-10 Telefonaktiebolaget Lm Ericsson Adaptive gain controller
AU714227B2 (en) * 1995-06-30 1999-12-23 Telefonaktiebolaget Lm Ericsson (Publ) Adaptive gain controller
EP0788265A3 (en) * 1996-01-31 1999-10-13 Victor Company Of Japan, Limited Synchronisation in multicarrier systems

Also Published As

Publication number Publication date
GB8421079D0 (en) 1984-09-26
GB8322440D0 (en) 1983-09-21

Similar Documents

Publication Publication Date Title
CA2201352A1 (en) Multi-channel transceiver having an adaptive antenna array and method
ATE79495T1 (en) FM RECEIVER WITH NOISE REDUCTION WHEN RECEIVING SIGNALS WITH &#39;&#39;RALEIGH&#39;&#39; FADER.
MY113119A (en) Transmitter/receiver apparatus
EP0550540A4 (en) Variable speaker muting based on received data
US5241689A (en) Digital signal processor audio compression in an RF base station system
DE69132021T2 (en) Device to facilitate communication
GB2112606A (en) Communication set and method
GB1509233A (en) Pcm telephone communication system
GB2146191A (en) Frequency division transmission equipment
AU1066601A (en) Receiver, transceiver, radio unit and method for telecommunication
US4281408A (en) Digital signal processing arrangement for controlling the level of a frequency-division multiplex signal
US4964304A (en) Audiometric testing method and apparatus
ATE261214T1 (en) METHOD FOR ALLOCATING RAKE BRANCHES AND RAKE RECIPIENTS
US6070088A (en) Mobile telephone set with automatic sound level control
FR2454231A1 (en) TRANSCEIVER WITH AUTOMATIC ALTERNATE CONTROL AND TELECOMMUNICATIONS NETWORK INCLUDING SUCH A TRANSCEIVER
US3938156A (en) Radio communication transmitter
US4229622A (en) Multiplexing speech signals
US4069454A (en) Transmitter-receiver employing automatic channel hunting and selection
EP0394063B1 (en) Radio communication apparatus having a simple structure
US5542112A (en) Method and apparatus for providing reliable signalling tones in a radio communication system
JP2590089B2 (en) Time division multiplex switching equipment
SU1270908A1 (en) Device for reception of single-side band radio communication signals
GB1103105A (en) Improvements in or relating to radiotelephony communication systems
EP0263177A1 (en) Audio mixer system and gain circuit therefor
SU416888A1 (en)

Legal Events

Date Code Title Description
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)