Transmitting signals over alternating current power networks

• US 4,371,867 A
• Filed: 10/01/1980
• Issued: 02/01/1983
• Est. Priority Date: 08/25/1977
• Status: Expired due to Term

• Current Assignee: LGZ Landis & Gyr Zug AG (Landis+Gyr Group AG)
• Original Assignee: LGZ Landis & Gyr Zug AG (Landis+Gyr Group AG)
• Inventors: Gander, Jean-Gabriel
• Primary Examiner(s): Groody, James J.
• Application Number:
  US06/192,827
• Time in Patent Office: 853 Days
• Field of Search: 340/310 R, 340/310 A, 340/310 CP, 340/163, 340/167 R, 340/171 R, 340/170, 340/825.06, 340/825.57, 340/825.7, 340/825.71, 307/3, 307/140, 455/108, 455/42, 455/110, 375/25, 375/59, 375/68
• US Class Current: 307/3
• CPC Class Codes: H02J 13/00009 using pulsed signals
• CPC Class Codes: H04B 2203/542 using zero crossing information
• CPC Class Codes: H04B 3/54 Systems for transmission via power distribution lines
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 40/121 using the power network as support for the transmission

Abstract

To transmit signals over an alternating current power distribution network, the network load parameters are modulated by means of non-linear elements or by varying the characteristics of components by electrical action dependent on a reference signal. A reference current, a capacitor voltage, a correction signal for varying an inductance of the network load, the network voltage, an external current source, the total current flowing through a divided network load or its zero passages and those of the network current form the reference signal. The network load is connected by a transformer to the network and comprises at least one series-resonant circuit.

Claims

1. A method of producing intelligence signals for transmission over the lines of an alternating current power supply network in response to an input reference signal comprising:

connecting a resonant circuit including a capacitive device to the lines of the power supply network;

controlling the charging and discharging of said capacitive device from the power supply network;

said charging and discharging of said capacitive device being controlled in response to intelligence to be transmitted to periodically charge said capacitive device so that said resonant circuit produces an intelligence signal for transmission over the power supply network; and

wherein said control is effected in dependence on a comparison of the current flowing through said resonant circuit and the reference signal.

2. A method according to claim 1 wherein said control is effected additionally in dependence on the voltage across said capacitive device.

3. A method according to claim 1 wherein a narrow or wide band signal is produced for transmission in dependence on the ratio:

space="preserve" listing-type="equation">u=ω

U.sub.N /LI.sub.o

in which U_N is the network voltage;

ω

=2π

;

f is the resonant frequency of said resonant circuit, L is the inductance of said resonant circuit; and

I_o is an adjustable reference current.

4. A method according to claim 3 wherein said control effects variation of said inductance.

5. A method according to claim 4 wherein said control is effected in dependence on a correction signal produced by comparison of the observed signal frequency on the line of the power supply network with the desired signal frequency of the reference signal.

6. A method according to claim 4 wherein said control for producing a wide band signal is effected additionally in dependence on the instantaneous magnitude of the network voltage on a specific network phase line.

7. A method according to claim 4 wherein said control is effected in dependence on the reference signal supplied by an external current source.

8. A method according to claim 1 wherein said resonant circuit is divided to provide two alternately operable resonant elements, and said control is effected in dependence on the total current flowing through said divided resonant circuit.

9. A transmitting device for producing intelligence signals over the lines of an alternating current power supply network comprising

a resonant circuit connected to the power supply network,

said resonant circuit including a capacitive device;

switch means connected to control charging and discharging of said capacitive device; and

control means connected to said switch means to periodically permit charging of said capacitive device from said power supply network so that said resonant circuit produces an intelligence signal on the power supply network; and

wherein said control means includes

a bistable circuit connected to control the state of said switch means in accordance with the state of said bistable circuit;

a comparator circuit responsive to current through said resonant circuit and operative to place said bistable circuit in a reset state when current through said resonant circuit reaches a predetermined level; and

a voltage detector responsive to the voltage across said capacitive device and operative to place said bistable circuit in a set state when a predetermined voltage across said capacitive device is detected.

10. A transmitting device according to claim 9 wherein said resonant circuit includes an inductor with a coupled winding connected to said control means.

11. A transmitting device according to claim 9 wherein said resonant circuit comprises at least one series resonant circuit resonant at an audio frequency.

12. A transmitting device according to claim 9 wherein said resonant circuit comprises an inductor and said capacitive device connected in series between said lines of said network, and said switch means is a switch connected across said capacitive device.

13. A transmitting device according to claim 9 wherein said switch means comprises a semiconductor element.

14. A transmitting device according to claim 9 wherein said switch means comprises a trigger triode.