MX9805005A - Sistema de deteccion de corriente de ciclo de modem para detectar una condicion de conexion en un telefono de extension. - Google Patents

Sistema de deteccion de corriente de ciclo de modem para detectar una condicion de conexion en un telefono de extension.

Info

Publication number
MX9805005A
MX9805005A MX9805005A MX9805005A MX9805005A MX 9805005 A MX9805005 A MX 9805005A MX 9805005 A MX9805005 A MX 9805005A MX 9805005 A MX9805005 A MX 9805005A MX 9805005 A MX9805005 A MX 9805005A
Authority
MX
Mexico
Prior art keywords
telephone
detect
extension telephone
loop current
line current
Prior art date
Application number
MX9805005A
Other languages
English (en)
Inventor
Robert Alan Pitsch
Original Assignee
Thomson Consumer Electronics
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
Priority claimed from GBGB9600002.1A external-priority patent/GB9600002D0/en
Priority claimed from GBGB9613608.0A external-priority patent/GB9613608D0/en
Application filed by Thomson Consumer Electronics filed Critical Thomson Consumer Electronics
Publication of MX9805005A publication Critical patent/MX9805005A/es

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/0701—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips at least one of the integrated circuit chips comprising an arrangement for power management
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/073—Special arrangements for circuits, e.g. for protecting identification code in memory
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0008—General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0013—Methods or arrangements for sensing record carriers, e.g. for reading patterns by galvanic contacts, e.g. card connectors for ISO-7816 compliant smart cards or memory cards, e.g. SD card readers
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0013—Methods or arrangements for sensing record carriers, e.g. for reading patterns by galvanic contacts, e.g. card connectors for ISO-7816 compliant smart cards or memory cards, e.g. SD card readers
    • G06K7/0021—Methods or arrangements for sensing record carriers, e.g. for reading patterns by galvanic contacts, e.g. card connectors for ISO-7816 compliant smart cards or memory cards, e.g. SD card readers for reading/sensing record carriers having surface contacts
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/0013—Methods or arrangements for sensing record carriers, e.g. for reading patterns by galvanic contacts, e.g. card connectors for ISO-7816 compliant smart cards or memory cards, e.g. SD card readers
    • G06K7/0086—Methods or arrangements for sensing record carriers, e.g. for reading patterns by galvanic contacts, e.g. card connectors for ISO-7816 compliant smart cards or memory cards, e.g. SD card readers the connector comprising a circuit for steering the operations of the card connector
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J9/00—Remote-control of tuned circuits; Combined remote-control of tuning and other functions, e.g. brightness, amplification
    • H03J9/06—Remote-control of tuned circuits; Combined remote-control of tuning and other functions, e.g. brightness, amplification using electromagnetic waves other than radio waves, e.g. light
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/22—Modifications for ensuring a predetermined initial state when the supply voltage has been applied
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
    • H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
    • H03K17/78—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled
    • H03K17/795—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled controlling bipolar transistors
    • H03K17/7955—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled controlling bipolar transistors using phototransistors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/738—Interface circuits for coupling substations to external telephone lines
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/738—Interface circuits for coupling substations to external telephone lines
    • H04M1/7385—Programmable or microprocessor-controlled
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/738—Interface circuits for coupling substations to external telephone lines
    • H04M1/74—Interface circuits for coupling substations to external telephone lines with means for reducing interference; with means for reducing effects due to line faults
    • H04M1/745—Protection devices or circuits for voltages surges on the line
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/82—Line monitoring circuits for call progress or status discrimination

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Artificial Intelligence (AREA)
  • Signal Processing (AREA)
  • Computer Security & Cryptography (AREA)
  • Electromagnetism (AREA)
  • General Engineering & Computer Science (AREA)
  • Telephonic Communication Services (AREA)
  • Interface Circuits In Exchanges (AREA)
  • Emergency Protection Circuit Devices (AREA)
  • Power Sources (AREA)
  • Devices For Supply Of Signal Current (AREA)
  • Selective Calling Equipment (AREA)
  • Telephone Function (AREA)
  • Optical Communication System (AREA)
  • Sub-Exchange Stations And Push- Button Telephones (AREA)
  • Noise Elimination (AREA)
  • Monitoring And Testing Of Exchanges (AREA)
  • Details Of Connecting Devices For Male And Female Coupling (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Communication Control (AREA)
  • Air Bags (AREA)
  • Filters And Equalizers (AREA)
  • Elimination Of Static Electricity (AREA)
  • Credit Cards Or The Like (AREA)
  • Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)

Abstract

Un circuito de monitoreo de línea telefonica utiliza un optoaislador (OPTO2) para convertir la corriente de la línea telefonica en un voltaje que se aplica a la entrada de un convertidor analogico a digital (118). Los valores de analogico a digital son valores brutos que representan la corriente de la línea telefonica. Los valores de analogico a digital se muestrean a un intervalo previamente determinado, con el fin de identificar los cambios introducidos por la oficina central de la compañía telefonica, y para tomar esos cambios en cuenta cuando se decide si se ha conectado (descolgado) un teléfono de extension. Cuando un cliente hace que se conecte un teléfono de extension, la corriente de línea se divide entre el teléfono de extension y el modem IRD (100), y se detecta este cambio.
MX9805005A 1995-12-22 1998-06-19 Sistema de deteccion de corriente de ciclo de modem para detectar una condicion de conexion en un telefono de extension. MX9805005A (es)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US917895P 1995-12-22 1995-12-22
GBGB9600002.1A GB9600002D0 (en) 1996-01-02 1996-01-02 Receiver for compressed television information
GBGB9613608.0A GB9613608D0 (en) 1996-06-28 1996-06-28 40mhz VCXO and loop filter for digital symbol lock timing for high speed modems

Publications (1)

Publication Number Publication Date
MX9805005A true MX9805005A (es) 1998-11-30

Family

ID=27268058

Family Applications (5)

Application Number Title Priority Date Filing Date
MX9805007A MX9805007A (es) 1995-12-22 1998-06-19 Un circuito de proteccion de equipo telefonico.
MX9805005A MX9805005A (es) 1995-12-22 1998-06-19 Sistema de deteccion de corriente de ciclo de modem para detectar una condicion de conexion en un telefono de extension.
MX9805008A MX9805008A (es) 1995-12-22 1998-06-19 Un sistema de regreso automatico de llamada del suscriptor.
MX9805004A MX9805004A (es) 1995-12-22 1998-06-19 Aislamiento electrico entre un receptor infrarrojo y otros circuitos electronicos.
MX9805001A MX9805001A (es) 1995-12-22 1998-06-19 Circuito de deteccion y modificacion de fallas.

Family Applications Before (1)

Application Number Title Priority Date Filing Date
MX9805007A MX9805007A (es) 1995-12-22 1998-06-19 Un circuito de proteccion de equipo telefonico.

Family Applications After (3)

Application Number Title Priority Date Filing Date
MX9805008A MX9805008A (es) 1995-12-22 1998-06-19 Un sistema de regreso automatico de llamada del suscriptor.
MX9805004A MX9805004A (es) 1995-12-22 1998-06-19 Aislamiento electrico entre un receptor infrarrojo y otros circuitos electronicos.
MX9805001A MX9805001A (es) 1995-12-22 1998-06-19 Circuito de deteccion y modificacion de fallas.

Country Status (12)

Country Link
US (1) US6442255B1 (es)
EP (5) EP0868807A1 (es)
JP (5) JP4452330B2 (es)
KR (5) KR100422229B1 (es)
CN (5) CN1126056C (es)
AU (5) AU1467397A (es)
BR (3) BR9612168A (es)
CA (1) CA2240287C (es)
DE (3) DE69604596T2 (es)
HK (1) HK1018651A1 (es)
MX (5) MX9805007A (es)
WO (5) WO1997023989A1 (es)

Families Citing this family (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2777727B1 (fr) * 1998-04-17 2000-06-30 Thomson Multimedia Sa Modem comportant un dispositif de detection de l'occupation d'une ligne telephonique
US6104791A (en) * 1998-06-11 2000-08-15 Conexant Systems, Inc. System and method for performing telephone line-in-use detection, extension pick-up detection, and remote hang-up detection in a modem
SE516164C2 (sv) * 2000-09-29 2001-11-26 Transmode Systems Ab Sändarkrets innefattande en ljuskälla, och ett kommunikationssystem
US20020112241A1 (en) * 2001-02-14 2002-08-15 Cocchi Ronald P. Internet service provider callback for satellite systems
KR20030005822A (ko) * 2001-07-10 2003-01-23 삼성전자 주식회사 스마트카드 보호용 리세트 장치
KR100459212B1 (ko) * 2001-11-06 2004-12-03 엘지.필립스 엘시디 주식회사 액정표시소자 제조용 스퍼터
US7269254B2 (en) * 2002-05-21 2007-09-11 Silicon Laboratories, Inc. Integrated driver circuitry
EP1391840A1 (en) * 2002-08-21 2004-02-25 Thomson Licensing S.A. Appliance with an IC card reader and overload protection
KR20040072881A (ko) * 2003-02-11 2004-08-19 엘지산전 주식회사 적외선 시리얼 변환 장치
US7239693B2 (en) * 2003-06-30 2007-07-03 Bellsouth Intellectual Property Corporation Network-based timed ring suppression
US7443967B1 (en) 2003-09-29 2008-10-28 At&T Intellectual Property I, L.P. Second communication during ring suppression
CA2490974C (en) * 2004-12-23 2016-05-17 Bce Inc Method, system and apparatus for establishing a packet-based connection with a dial up modem
RU2413379C2 (ru) * 2005-09-15 2011-02-27 Тайко Сэйфти Продактс Канада Лтд. Связной интерфейс телефонной линии
US7835516B2 (en) 2005-12-29 2010-11-16 Tyco Safety Products Canada Ltd. Direct access arrangement device
CN101472010B (zh) * 2007-12-27 2011-05-18 华为技术有限公司 一种实现电话台灯管理的方法、系统及装置
CN101295349B (zh) * 2008-05-30 2011-07-06 北京飞天诚信科技有限公司 一种智能卡数据截取系统及控制方法
US8280070B2 (en) * 2008-08-20 2012-10-02 Siemens Industry, Inc. Arrangement and method for communicating audio and DC signals
CN101615152B (zh) * 2009-07-13 2013-07-03 中兴通讯股份有限公司 存储卡热插拔故障的检测方法和装置
CN102025412B (zh) * 2009-09-16 2014-11-05 海洋王照明科技股份有限公司 一种红外接收电路
CN103873610A (zh) * 2012-12-13 2014-06-18 上海共联通信信息发展有限公司 一种使用寿命长的公用电话终端设备
CN109561194B (zh) * 2018-12-27 2021-08-06 深圳市新国都支付技术有限公司 一种pos机拨号方法和装置
CN112054482B (zh) * 2020-08-06 2022-05-06 三峡大学 基于dtw算法的换流变压器零序差动保护防误动方法

Family Cites Families (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7614118A (nl) * 1976-12-20 1978-06-22 Philips Nv Schakeling voor het beschermen van telefoon- lijnen.
US4132864A (en) 1977-04-28 1979-01-02 International Business Machines Corporation Digital measurement of the DC value in an AC signal adapted to telephone off-hook detection
US4203006A (en) * 1978-04-20 1980-05-13 Prentice Corporation Direct access coupler
US4431867A (en) * 1981-06-15 1984-02-14 Hayes Microcomputer Products, Inc. Modem with low part count and improved demodulator
CH661397A5 (en) * 1984-05-16 1987-07-15 Autophon Ag Telephone subscriber station with an electronic switch which opens and closes the subscriber loop
JPS61289480A (ja) * 1985-06-17 1986-12-19 Sankyo Seiki Mfg Co Ltd Ｉｃカ−ドリ−ダ
US4760355A (en) * 1985-11-04 1988-07-26 Glen Dash Electromagnetic emission control system
JPS62282389A (ja) * 1986-05-31 1987-12-08 Toshiba Corp 携帯可能記録媒体の読取・書込装置
FR2604555B1 (fr) * 1986-09-30 1988-11-10 Eurotechnique Sa Circuit integre du type circuit logique comportant une memoire non volatile programmable electriquement
IT1197977B (it) 1986-11-13 1988-12-21 Sgs Microelettronica Spa Circuito telefonico, integrabile monoliticamente, per l'invio di segnali di suoneria in una linea telefonica d'utente ed il riconoscimento dello sgancio in fase di suoneria
US4807278A (en) * 1987-05-11 1989-02-21 Ross David W Telecommunication controller having a telephone line sharing function
US4958371A (en) * 1988-04-19 1990-09-18 Control Data Corporation Method and apparatus for determining when a telephone handset is off-hook
JP2563475B2 (ja) * 1988-05-13 1996-12-11 沖電気工業株式会社 マイクロコンピュータ及びマイクロコンピュータを内蔵したｉｃカード
JPH0255355U (es) * 1988-10-11 1990-04-20
JPH02135589A (ja) * 1988-11-15 1990-05-24 Omron Tateisi Electron Co Ｉｃカードシステム
JPH03163938A (ja) * 1989-11-22 1991-07-15 Hitachi Ltd 信号伝送回路
DE4008939A1 (de) * 1990-03-20 1991-09-26 Elero Antrieb Sonnenschutz Elektronische rolladensteuerung mit steckbarem steuerteil
SE466726B (sv) * 1990-08-20 1992-03-23 Kent Lennartsson Anordning vid distribuerat datorsystem
GB9021222D0 (en) * 1990-09-28 1990-11-14 Raychem Ltd Circuit protection device
US5291545A (en) * 1990-10-02 1994-03-01 Intertex Data Ab Apparatus and method for determining the state of a telephone line
US5493469A (en) * 1991-01-18 1996-02-20 Mildred A. Lace Surge protection for data lines
US5241565A (en) 1991-06-25 1993-08-31 Microcom Systems, Inc. Method and apparatus for effecting efficient transmission of data
US5239575A (en) 1991-07-09 1993-08-24 Schlumberger Industries, Inc. Telephone dial-inbound data acquisition system with demand reading capability
EP0603436B1 (en) * 1992-12-21 1999-03-03 STMicroelectronics Pte Ltd. Parallel phone detection circuit
JP3426293B2 (ja) * 1993-07-26 2003-07-14 株式会社リコー 通信制御装置
US5422939A (en) * 1993-08-05 1995-06-06 Schlumberger Industries, Inc. Parallel off-hook detection for both line-available and phone pick-up detection
US5488654A (en) * 1993-09-29 1996-01-30 Telegenics, Inc. Telemetry device including a dynamic off-hook detector capable of operationg in a pulse-dialing environment
US5535265A (en) * 1993-11-15 1996-07-09 Ast Research, Inc. Method and circuitry for controlling voice mail, call logging and call blocking functions using a modem
US5494573A (en) * 1994-02-14 1996-02-27 Aquatec Water Systems, Inc. Reverse osmosis water purification diagnostic system
CN1096186C (zh) * 1994-12-30 2002-12-11 汤姆森消费电子有限公司 具有自动回叫装置的调制解调器
US6134321A (en) * 1995-12-22 2000-10-17 Thomas Licensing S.A. Modem loop current detect system to detect an off-hook condition in an extension telephone

Also Published As

Publication number Publication date
EP0868810A1 (en) 1998-10-07
WO1997023989A1 (en) 1997-07-03
MX9805007A (es) 1998-11-30
AU1467397A (en) 1997-07-17
KR19990072225A (ko) 1999-09-27
JP2000502534A (ja) 2000-02-29
JP4452330B2 (ja) 2010-04-21
CN1209209A (zh) 1999-02-24
CN1209245A (zh) 1999-02-24
DE69620023D1 (de) 2002-04-25
KR19990072219A (ko) 1999-09-27
WO1997023840A1 (en) 1997-07-03
WO1997023954A1 (en) 1997-07-03
DE69620023T2 (de) 2002-08-22
EP0868805A1 (en) 1998-10-07
JP2000516358A (ja) 2000-12-05
DE69636523T2 (de) 2007-04-05
AU715450B2 (en) 2000-02-03
KR100422229B1 (ko) 2004-06-16
CN1095269C (zh) 2002-11-27
AU1290897A (en) 1997-07-17
EP0868810B1 (en) 2006-09-06
AU1151997A (en) 1997-07-17
EP0868704B1 (en) 1999-10-06
BR9612170A (pt) 1999-07-13
KR19990072224A (ko) 1999-09-27
AU1424497A (en) 1997-07-17
CN1097878C (zh) 2003-01-01
DE69604596T2 (de) 2000-01-20
EP0868781A1 (en) 1998-10-07
CN1126056C (zh) 2003-10-29
BR9612176A (pt) 1999-07-13
CN1219304A (zh) 1999-06-09
WO1997023985A1 (en) 1997-07-03
EP0868704A1 (en) 1998-10-07
CN1166162C (zh) 2004-09-08
EP0868781B1 (en) 2002-04-10
CN1209243A (zh) 1999-02-24
MX9805008A (es) 1998-11-30
BR9612168A (pt) 1999-07-13
DE69636523D1 (de) 2006-10-19
KR19990072221A (ko) 1999-09-27
JP2000502476A (ja) 2000-02-29
CA2240287C (en) 2002-09-10
JP2000513515A (ja) 2000-10-10
HK1018651A1 (en) 1999-12-30
JP2000505257A (ja) 2000-04-25
KR100490016B1 (ko) 2005-08-31
JP4077877B2 (ja) 2008-04-23
CN1205821A (zh) 1999-01-20
KR100419331B1 (ko) 2004-05-24
KR100408983B1 (ko) 2004-03-24
KR19990072220A (ko) 1999-09-27
AU1419997A (en) 1997-07-17
BR9612170B1 (pt) 2009-05-05
MX9805004A (es) 1998-11-30
MX9805001A (es) 1998-11-30
JP3573350B2 (ja) 2004-10-06
EP0868807A1 (en) 1998-10-07
KR100454013B1 (ko) 2005-05-09
CA2240287A1 (en) 1997-07-03
EP0868805B1 (en) 2002-03-20
CN1166158C (zh) 2004-09-08
US6442255B1 (en) 2002-08-27
DE69604596D1 (de) 1999-11-11
JP4044962B2 (ja) 2008-02-06
WO1997023987A1 (en) 1997-07-03

Similar Documents

Publication Publication Date Title
MX9805005A (es) Sistema de deteccion de corriente de ciclo de modem para detectar una condicion de conexion en un telefono de extension.
US4803718A (en) Hold detecting and control circuit for a key telephone system
US5218635A (en) Low-frequency alternating current signal detector, in particular for central office line interface circuits
CA2172563C (en) Subscriber line interface and power circuit
TW265500B (es)
NO944947L (no) Fremgangsmåte og anordning for å utvide opplösningen hos en sigma-delta analog/digital omformer
EP0116291A3 (en) Ring trip detection system
KR900010403A (ko) 링깅 검출기 및 링깅 신호 검출 방법
US5668870A (en) Audible signaling device for informing when a telephone line is available or in use
US5901219A (en) Method for ring signal detection
CA2318450A1 (en) System and method for automatic pbx detection
TW498661B (en) Line interface circuit and information communicating apparatus using it
EP0600644A1 (en) Ring-trip detection using ring voltage and current
CA2082321C (en) Circuit to detect the hook status and ringing at the cpe end of a telephone network
GB1496061A (en) Electrical converter and fault detecting circuit therefor
US6944286B1 (en) Ground key detection circuit and method for interference-resistant detection of the activation of a ground key for telephones
KR970008869A (ko) 비교기를 이용한 링신호 검출회로 및 방법
CA2032651A1 (en) Telephone subscriber line voltage change detection
JP2858565B2 (ja) 二線式加入者回線用障害検出方法及びそれを適用した障害検出回路
KR200142808Y1 (ko) 전화기 연결상태 확인 장치
JPS6430395A (en) Key telephone system
TW234803B (en) Power relay control circuit for network communication device
KR100547885B1 (ko) 통신 단말기의 복합 신호 감지회로 및 그 처리방법
SU1195477A1 (ru) Устройство дл приема ответа абонента
KR100264033B1 (en) Interface device of network connection unit using a telephone line