WO1998039888A3 - A method and apparatus for shaping the signal spectrum of a transmit signal of a modem - Google Patents

A method and apparatus for shaping the signal spectrum of a transmit signal of a modem Download PDF

Info

Publication number
WO1998039888A3
WO1998039888A3 PCT/IE1998/000020 IE9800020W WO9839888A3 WO 1998039888 A3 WO1998039888 A3 WO 1998039888A3 IE 9800020 W IE9800020 W IE 9800020W WO 9839888 A3 WO9839888 A3 WO 9839888A3
Authority
WO
WIPO (PCT)
Prior art keywords
symbol level
modem
signal
shaping
transmit signal
Prior art date
Application number
PCT/IE1998/000020
Other languages
French (fr)
Other versions
WO1998039888A2 (en
Inventor
Michael Mclaughlin
Original Assignee
Fernway Ltd
Michael Mclaughlin
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 Fernway Ltd, Michael Mclaughlin filed Critical Fernway Ltd
Priority to AU64170/98A priority Critical patent/AU6417098A/en
Priority to GB9920892A priority patent/GB2337433B/en
Publication of WO1998039888A2 publication Critical patent/WO1998039888A2/en
Publication of WO1998039888A3 publication Critical patent/WO1998039888A3/en

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/38—Synchronous or start-stop systems, e.g. for Baudot code
    • H04L25/40—Transmitting circuits; Receiving circuits
    • H04L25/49—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems
    • H04L25/4917—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems using multilevel codes
    • H04L25/4927—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems using multilevel codes using levels matched to the quantisation levels of the channel

Landscapes

  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Dc Digital Transmission (AREA)

Abstract

A method for shaping the signal spectrum of a transmit signal for placing on an output line (3) of a modem (1) wherein a plurality of symbol levels (8) are derived from a user data input bit stream (2) fed to the modem (1), and an alternative symbol level (9) is assigned to each symbol level. The method comprises passing each symbol level (8) and its alternative symbol level (9) through a digital filter (12, 14, 15) having a relatively high output at undesired frequencies and a relatively low output at desired frequencies. The energies of the output signals (20, 21) from the filter (12, 14, 15) corresponding to the respective symbol level (8) and the alternative symbol level (9) are determined and subtracted (24) one from the other. Should the difference between the two energies exceed a predetermined value (Vref), then the one of the symbol level (8) and the alternative symbol level (9) of lowest energy is selected for the transmit signal and applied to the output line (3).
PCT/IE1998/000020 1997-03-05 1998-03-05 A method and apparatus for shaping the signal spectrum of a transmit signal of a modem WO1998039888A2 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU64170/98A AU6417098A (en) 1997-03-05 1998-03-05 A method and apparatus for shaping the signal spectrum of a transmit signal of amodem
GB9920892A GB2337433B (en) 1997-03-05 1998-03-05 A method and apparatus for shaping the signal spectrum of transmit signal of a modem

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IES970152 1997-03-05
IE970152 1997-03-05

Publications (2)

Publication Number Publication Date
WO1998039888A2 WO1998039888A2 (en) 1998-09-11
WO1998039888A3 true WO1998039888A3 (en) 1998-12-03

Family

ID=11041399

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IE1998/000020 WO1998039888A2 (en) 1997-03-05 1998-03-05 A method and apparatus for shaping the signal spectrum of a transmit signal of a modem

Country Status (4)

Country Link
AU (1) AU6417098A (en)
GB (1) GB2337433B (en)
IE (1) IES980160A2 (en)
WO (1) WO1998039888A2 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0209902A2 (en) * 1985-07-24 1987-01-28 Nec Corporation Multilevel modulator comprising a compact error correcting code producing unit
US5249200A (en) * 1991-07-30 1993-09-28 Codex Corporation Device and method for combining precoding with symbol-rate spectral shaping
US5291521A (en) * 1990-05-29 1994-03-01 At&T Bell Laboratories Index assignment in redundancy-coded data communication systems
US5455839A (en) * 1991-12-27 1995-10-03 Motorola, Inc. Device and method for precoding
EP0863642A2 (en) * 1997-03-03 1998-09-09 PC-Tel, Inc. Shaping code for PCM modems

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0209902A2 (en) * 1985-07-24 1987-01-28 Nec Corporation Multilevel modulator comprising a compact error correcting code producing unit
US5291521A (en) * 1990-05-29 1994-03-01 At&T Bell Laboratories Index assignment in redundancy-coded data communication systems
US5249200A (en) * 1991-07-30 1993-09-28 Codex Corporation Device and method for combining precoding with symbol-rate spectral shaping
US5455839A (en) * 1991-12-27 1995-10-03 Motorola, Inc. Device and method for precoding
EP0863642A2 (en) * 1997-03-03 1998-09-09 PC-Tel, Inc. Shaping code for PCM modems

Also Published As

Publication number Publication date
AU6417098A (en) 1998-09-22
IES80431B2 (en) 1998-07-01
GB2337433A (en) 1999-11-17
GB2337433B (en) 2002-03-06
WO1998039888A2 (en) 1998-09-11
GB9920892D0 (en) 1999-11-10
IES980160A2 (en) 1998-07-01

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