Telecommunication system and modem for transmission of modulated information signals over power supply lines

• US 5,892,795 A
• Filed: 08/01/1996
• Issued: 04/06/1999
• Est. Priority Date: 08/02/1995
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Paret, Dominique
• Primary Examiner(s): Pham, Chi H.
• Assistant Examiner(s): LUTHER, WILLIAM A
• Application Number:
  US08/692,292
• Time in Patent Office: 978 Days
• Field of Search: 375/344, 375/222, 375/219, 375/259, 375/268, 375/271, 375/285, 379/66, 340/310.01, 340/310.02, 340/310.03, 340/310.06, 340/310.04, 340/310.05, 340/310.07, 340/310.08, 455/3.3, 455/270
• US Class Current: 375/222
• CPC Class Codes: H04B 2203/5416 by adding signals to the wave form of the power source
• CPC Class Codes: H04B 2203/5425 improving S/N by matching impedance, noise reduction, gain control
• CPC Class Codes: H04B 2203/5491 using filtering and bypassing
• CPC Class Codes: H04B 2203/5495 having measurements and testing channel
• CPC Class Codes: H04B 3/542 the information being in digital form

Abstract

A telecommunication system for transmission along power supply lines of modulated information signals having a selected carrier frequency. The system includes a plurality of communication devices connected along the supply lines, each including a microcontroller and a modem. The modem includes an interface module which establishes a link to the power supply lines for modulated information signals, a transmission module which contains a digital modulator followed a digital/analog converter, and a receiving module. The receiving module includes a digital filter connected between an analog/digital converter and a digital demodulator. The digital filter is adapted to the carrier frequency of modulated information signals present on the power supply lines, whereby the modem can operate at any selected frequency over a broad frequency range.

Claims

1. A telecommunication system comprising a plurality of communication devices which communicate by transmission of information signals along power supply lines commonly connected thereto, the information signals being in the form of digitally modulated carrier signals, each of said communication devices including a microcontroller and a modem;

each of said modems comprising;

an interface module which establishes a link to the power supply lines for transmission and reception of information signals;

a transmission module which includes a digital modulator followed by a digital/analog converter having an output connected to the interface module, the digital modulator being controlled by said microcontroller to modulate a carrier signal having a frequency selected by said microcontroller; and

a receiving module which includes an analog/digital converter having an input connected to the interface module and an output which is followed by a digital demodulator;

characterized in that the receiving module further includes a digital filter connected between the output of the analog/digital converter and an input of the digital demodulator, said digital filter being timed by a clock signal supplied by said microcontroller corresponding to the frequency of an information signal received by the interface module from the power supply lines.

2. A telecommunication system as claimed in claim 1, wherein the clock signal supplied to the digital filter is a common clock signal supplied by the microcontroller for also timing the digital modulator, the digital/analog converter and the analog/digital converter.

3. A telecommunication system as claimed in claim 2, wherein the modem further comprises a ROM for storing in sampled form a carrier signal for use by the digital modulator in forming an information signal, read out of the ROM being timed by said common clock signal.

4. A telecommunication system as claimed in claim 3, wherein the carrier signal stored in sampled form in the ROM has an amplitude in accordance with two transitory ranges, a first range at the beginning of a transmission and during which the carrier signal amplitude progressively rises up to a fixed nominal value, and a second range at the end of a transmission and during which the carrier signal amplitude progressively drops to zero.

5. A telecommunication system as claimed in claim 3, wherein the digital filter comprises a further ROM for storing various sets of coefficients corresponding to various filter patterns, said further ROM being addressable by the microcontroller.

6. A modem for inclusion in a communication device for use in a telecommunication system wherein communication with said device is by transmission of information signals along power supply lines coupled thereto, the information signals being in the form of digitally modulated carrier signals;

said modem comprising;

an interface module which establishes a link to the power supply lines for transmission and reception of information signals;

a transmission module which includes a digital modulator followed by a digital/analog converter having an output connected to the interface module, the digital modulator being controlled by said microcontroller to modulate a carrier signal having a frequency selected by said microcontroller; and

a receiving module which includes an analog/digital converter having an input connected to the interface module and an output which is followed by a digital demodulator;

characterized in that the receiving module further includes a digital filter connected between the output of the analog/digital converter and an input of the digital demodulator, said digital filter being timed by a clock signal corresponding to the frequency of an information signal received by the interface module from the power supply lines.

7. A modem as claimed in claim 6, wherein the clock signal for timing the digital filter is a common clock signal for also timing the digital modulator, the digital/analog converter and the analog/digital converter.

8. A modem as claimed in claim 7, wherein said modem further comprises a ROM for storing in sampled form a carrier signal for use by the digital modulator to forming an information signal, read out of the ROM being timed by said common clock signal.

9. A modem as claimed in claim 8, wherein the carrier signal stored in sample form in the ROM has an amplitude in accordance with two transitory ranges, a first range at the beginning of a transmission and during which the carrier signal has an amplitude which progressively rises up to a fixed nominal value, and a second range at the end of a transmission and during which the carrier signal amplitude progressively drops to zero.

10. A modem as claimed in claim 9, wherein the digital filter comprises a further ROM for storing various sets of coefficients corresponding to various filter patterns.