FR2507030A1 - Transmission system for coded data on power lines - uses low frequency modulator for high frequency carrier to transmit digitally coded data with noise filtering - Google Patents

Abstract

A data coding circuit comprises a keyboard with a BCD encoder. Several memory circuits are validated by a shift register which controls interrogation of the circuit after loading of the last memory. These memories have a reset to zero facility. A scanner circuit is driven by a clock whose pulses determine the sweep speed for the different data sources. The scanner connects these sources to a low frequency oscillator whose frequency is controlled by a voltage from resistors. These are connected to the scanner through a switch circuit. The LF oscillator modulates an HF oscillator providing the carrier for transmission on the power lines through a transformer which is capacitively coupled to the lines.

Description

The subject of the present invention is a method of transmitting and receiving coded information information between at least two points of a network for the transport or distribution of electrical energy and the means for implementing the method.

Different systems of transmission and reception of information are known for example for the remote control of various electrical devices for the transmission of parametric data and for the purposes of control and monitoring of organs or premises.

To avoid installing a wired network specific to transmission and reception systems, it is known to use the transport or distribution network for electrical energy, for example conveying in a room several electrical currents out of phase with each other.

The major drawback of using such a network is that posed by background noise from vehicles by the various lines which can modify the signals received and therefore the information transmitted.

To overcome this drawback, the power of the transmitter is increased to strengthen the signal-to-noise ratio at the receiver.

 Ea-.power transmitter being limited, the receiver should not be too far from it to maintain a correct signal to noise ratio.

In addition, in many cases, it is desirable to transmit and receive signals between at least two points of at least two lines of the network each carrying an alternating current out of phase with that carried by the other line.

To this end, the systems of the prior art provide electrical means for coupling the different lines at a determined point in the network.

Usually these means consist of inductors and capacitors allowing the passage of signals and ensuring the separation of the currents normally carried by the lines.

One of the drawbacks of these systems is that it requires intervention on the electrical network by highly qualified personnel.

We know that a high frequency wave injected into a line of the network transmits its energy by indllction to the other lines with a notable weakening.

As a result, signals transmitted from line to line in this way are systematically drowned in noise
For this reason, it has been preferred hitherto to use the systems of the prior art which involve high powers for the transmission and which call for line coupling means.

The object of the present invention is to overcome the above-mentioned drawbacks by implementing a method for transmitting and receiving coded information, for example in digital form formed by a signal train between at least two points of a distribution or transport network of electrical energy in a room which for transmission does not require significant powers for compliance with the regulations in force and does not require inductive or capacitive coupling of the different lines of the network.

Another object of the present invention is the implementation of a method allowing the discrimination of the signals even with a high percentage of noise.

To this end, the method according to ~ ltinvention of transmission and reception of coded information formed dtau at least two points dtun distribution or transport network of electrical energy is essentially characterized in that it consists in successively interrogating one or more sources for detect at their output the presence of a signal to be transmitted, to generate, if a signal is detected, a low frequency wave whose frequency value characterizes the source, to modulate a high frequency wave using the low frequency wave, to inject on one of the lines of the network the carrier wave modulated successively by the low frequency waves and in that at the level of the reception said process consists in amplifying according to a great ratio the background noises and the high frequency waves, to discard after demodulation the low frequency waves amplified or not, to select the low frequency waves, according to the value of their frequency, to be addressed if a low wave if the frequency is present, signals identical to those emitted on corresponding outputs.

According to another characteristic of the invention, the system for transmitting and receiving information consisting of at least one transmitter and at least one receiver connected to the same line of the network or to different lines is essentially characterized in that said receiver consists in particular of a high frequency amplification stage amplifying the background noise of the lines and the high frequency wave train and a low frequency amplification stage which clips the received signals.

Other advantages and characteristics of the invention will appear on reading the description of a preferred embodiment with reference to the accompanying drawings in which
- Figure I is a block diagram of the transmitter according to 1 invention.

 - Figure 2 is a block diagram of the receiver according to the invention.

- Figure 3 is a schematic view of the transmitter according to
the invention.

 - Figure 4 is a schematic view of the receiver according to the invention.

- Figure 5 is a block diagram of another form of
realization of the system according to the invention.

The method according to the invention for transmitting and receiving information between at least two points of a network: 1 for distributing or transporting electrical energy consists in successively interrogating one or more sources A, B, C, D , to detect at their output the presence of a signal to transmit, to generate? If a signal is detected, a low frequency wave f1, or f2, or 3 or 4 whose frequency value characterizes the source to modulate using this wave a high frequency wave or carrier fO to be injected on one of the lines i1l2 , 13 of network 1 the modulated carrier
At the reception level, the method according to the invention consists in amplifying the background noise and the high frequency waves received in the form of a continuous wave train on a line 11, 12, or 13 to clip after demodulation the low frequency waves. , to select the said waves according to the value of their frequency to control the addressing of identical signals to those present at the terminals of the sources A, B, C or D on outputs corresponding to, b, c, d.

The signals present at the terminals of the sources A, B, C or D are defined by a logic state O or 1 translated by the absence or the presence of a DC voltage.

The set of signals present at the terminals of the sources is the translation in binary form of the information to be transmitted.

 The successive interrogation of each of these sources makes it possible to detect at their terminal a logic state O or 1 and to generate a low frequency wave f1, f2, f3, f4, If for example a logic level 1 is presentJ whose frequency value characterizes the source .

At this level as we understand ltinformation on to be transmitted is translated by a succession of waves of different frequencies forming a train of low frequencies waves continuous or not
The low frequency waves f1, f2, f3, f4 frequency modulate the carrier fO to form a continuous train dto: high frequency back translating the information to be transmitted.

In this high frequency wave train the presence of the frequency fo is the translation of a logic state O to one or more sources.

As known, the frequency of the carrier wave fO is chosen as a function of the network impedance to minimize the losses.

Thus for the transmission and reception of coded information via an EDF 220V network the frequency fO of the wave will be substantially equal to 100 KHZ.

it is quite obvious that this value is given only as an indication and can vary according to the impedance of such type of network.

The continuous train of high frequency waves is injected into a line li of the network by inductive and capacitive way and is transmitted by induction to lines 12 and 13
As can be seen, the lines 11S12, 13 are not coupled elec trically, which is not the case with the systems of the prior art.

 It should be noted that at this stage the tral srlAiscs information undergoes a noticeable weakening and is therefore drowned in the noise of the lines.

In addition, the background noise of the lines that the sudden variations of the network voltage modulate in amplitude the high frequency waves.

This drawback is eliminated at the reception level by a new processing of the signals which are the subject of the invention.

At the reception, the high frequency wave train and the background noise extracted from one of the lines are amplified according to a large ratio and after demodulation the low frequency waves are clipped at a strictly identical voltage level whatever the voltage. low frequency waves.

According to a preferred form the low frequency waves after demodulation undergo an amplification one of the purposes of which is the secreting of said waves.

According to another variant, the low frequency waves are amplified and then clipped.

At this level, the information is translated by a continuous train or not of low frequency waves clipped at a fixed voltage level which has the effect of reducing the background noise to the same level.

The presence in the high frequency wave train of a frequency fO results in the presence in the low frequency rumble train of a hole corresponding to a logic state O on the corresponding output or outputs.

Depending on the value of the low frequency waves of the logic states 1 will be addressed on the corresponding outputs and stored.

For this purpose, the low frequency waves of the wave train are selected according to their value to switch the corresponding outputs a, b, c, d
The set of signals present at these outputs is the binary translation of the information received.

The signals present at the outputs assbssc> d, are respectively identical to those present at sources A, B, C, D and are defined by the presence or absence of a DC voltage.

The transmission or reception system for the application of the method defined above is constituted by at least one transmitter 4 coupled to one of the lines of the network and by at least one receiver 5 coupled to the same line or to a different line.

The transmitter 4 consists of a interrogation device 6 of one or more sources A, B, C, or D associated with at least one low frequency oscillator 7 generating at least one low frequency wave and by at least one high frequency oscillator 8 generating a carrier frequency modulated by low frequency waves.

Sources A, B, C, or D constitute the outputs of a unit for coding information transforming analog or digital data, into electrical pulses stored and addressed or not, this depending on the content of the information on said sources for define logical states 1 or 0 at their terminals.

 Thus, the transmission and reception system can be associated with a measurement assembly of one or more parameters constituted by at least one measurement probe and an analog-to-digital converter or as shown in fig. 3 be associated with a coding unit 9 known per se, of numbers or numbers, comprising a keyboard 10 associated with a BCD encoder 11, one or more memories 12 validated by a shift register 13 controlling the interrogation of the device after loading the last memory.

As known, the unit 9 includes means for resetting to zero the memories which also act on the transmitter for the emission of a wave intended to control the resetting to means of a set of decoding of the associated information. at the receiver outputs.

According to the embodiment shown in fig.3, the device 6 consists of a scanner controlled by a clock 14 delivering pulses which determine its scanning speed and therefore the speed of interrogation of the different sources.

As the sweep progresses, the scanner relates the oscillator BF to each of the sources A, B, C, or D and generates for each source a low frequency wave if a logic state is present.

To differentiate each source, the oscillator generates waves of different frequencies.

To this end, according to the embodiment shown in FIG. 3, the oscillator is voltage controlled by resistors 15 each associated with a switching member 16 connected to one of the outputs of the scanner.

According to the embodiment shown in fig.3, the switching member is constituted by a transistor connected by its base to one of the outputs of the scanner and by its collector to the resistance.

If a voltage is applied to the base of the transistor, translating a logic state 1 present at the corresponding source, it goes from a blocked state to a saturated state, which causes a voltage drop across the corresponding resistance.

The oscillator will generate a low frequency wave whose frequency value depends on this voltage drop and therefore on the resistance value.

Advantageously, the resistors 15 are adjustable, which makes it possible to adjust the frequency of the waves generated by the oscillator.

As is understood as the scanning progresses, the oscillator will generate waves of different frequencies each corresponding to a source at the terminals of which a logic state 1 is detected.

The low frequency wave train generated by the oscillator will attack the high frequency stage to modulate the carrier wave FO.

According to the embodiment shown in fig.3, the high frequency stage consists of an oscillator of the type: 'Hartley "but it is obvious that an oscillator of any other suitable type can be used.

The high frequency wave train is injected onto one of the lines of the network by means of an output cell consisting of a choke 17 at the terminals of which two capacitors 18 are connected.

This cell is connected to two plug sockets which can be plugged into a female socket on network 1.

The receiver 5 according to the invention as shown diagrammatically in FIG. 2 comprises an input cell 19 coupled to one of the lines of the network, a tuning stage 20, a stage 21 for amplifying the high frequency waves and background noise, a demodulator 22 ensuring the separation of the low frequency waves from the carrier , a low frequency amplification stage 23 and one or more selective filters 24 each associated with an integrator 25.

The input cell consists of a transformer comprising a primary winding and a secondary winding.

At the terminals of the primary winding are connected two capacitors isolating the transformer from the current carried by the line.

 The secondary of the transformer forms with a capacity connected in parallel to these terminals the connection block 20 having a maximum impedance for the frequency 10.

The tuning block 20 attacks the amplification stage for high frequency waves and background noise.

As can be seen in fig.3, this stage is for example constituted by a transistor but it goes without saying that it can be constituted by any other electronic component provided for this purpose.

The output of the high frequency amplification stage is connected by means of a connection capacitance to a demodulation stage known per se, comprising a local oscillator.

The output of the demodulation stage, for example constituted by an integrated circuit of the SE 565 type, delivers the low frequency waves.

These waves are amplified by the amplifier 23 with high gain and clipped which brings the background noise and said waves to a strictly identical level.

As can be understood at this level, this stage delivers a rigorously constant voltage whatever the voltages of the high frequency waves detected.

As a result, the amplitude modulation of high frequency waves by background noise no longer occurs at this level.

According to the exemplary embodiment of FIG. 4, the clipping of the low frequency waves is carried out by the amplifier 23, the latter delivering waves of the square type with constant amplitude.

According to another exemplary embodiment, the amplifier LF is followed by a compressor, or limiter.

The low frequency waves present at the output of the amplifier 23 or of the limiter are applied to the input of the selective filters which makes their selection, each set to a single frequency of the low frequency waves emitted or received and delivering if this there is a overvoltage connection at their input.

As shown, these elective filters or band pass filters consist of an operational amplifier, mounted in feedback, associated with a network of capacitor and resistance constituting a band stop filter.

One of the resistors is adjustable to adjust the frequency for which the selective filter must deliver the tuning overvoltage.

The filters 24 are each associated with an integrator 25 constituted by a diode 26 rectifying the voltage delivered by said filter, by a transistor 27 whose base is attacked by the diode and by a capacitor 28 connected in parallel with a resistor arranged in series with the bias resistor of the collector of the transistor.

The purpose of transistor 27 is to amplify the output voltage of the filter and the capacitor to regulate the voltage to properly drive the base of a transistor 29 mounted in switching mode.

This transistor therefore delivers logic states 0 or 1 on the corresponding output as a function of the response of the filter 24 at the frequency it receives.

The outputs a, b, c2 or d in this case consist of the collectors of the transistors 29.

The outputs a, b, c, or d constitute the inputs of a decoding unit 30 of the information transmitted.

This unit in the embodiment shown in fig.4 includes one or more memories 31 each associated with a BCD converter 32 and a 7 segment display 33.

The resetting of the memories is controlled by one of the selective filters 25 which reacts by delivering a tuning overvoltage when the corresponding low frequency wave whose emission is controlled by the coding unit is present at its input.

The system as described is particularly suitable for transmitting digital data, but it goes without saying that it can be associated, for example, with means for monitoring premises, as shown diagrammatically in FIG. 5.

Depending on the case, the system can be associated with a means ensuring the monitoring of a particular point or a particular space of a room or be associated with several means each assigned to the monitoring of one or more points or spaces of said room .

For this purpose according to a simplified version shown in fig.5, the system is associated with a single monitoring means 34 of one of the particular openings dtun local.

The transmitter of the system according to this version is no longer provided with an interrogation member 6 and comprises a generator 35 successively producing logic states 0 and 1 whose operation is controlled by a memorized pulse delivered by the monitoring means such as for example a push button.

The generator 35 drives the low frequency oscillator 7.

The receiver of the system according to this version is equipped only with a single filter 25 controlling, via the intermediary or not of an integrator 26, an audible or visual alarm.

The transmission and reception system according to the invention allows the detection of waves of very low amplitudes and the discrimination of said waves even drowned in a high percentage of noise.

For its operation, such a system does not involve significant powers and for its implementation does not use a capacitive and / or inductive torque of the phases of the network.

 It goes without saying that the present invention can receive all arrangements and all variants without departing from the scope of this patent.

Claims (1)

CLAIMS R1 / Method for transmitting and receiving coded information between at least two points of a distribution or transport network of electrical energy comprising several lines (11,12,13) each carrying a phase current with respect to to those carried by the other lines, characterized in that it consists in successively interrogating several sources (A, B, C, D) to detect a signal at their terminals, the set of signals present at said sources being the translation of the information to be transmitted, to generate if a signal is detected, a low frequency wave (f1,2,3,4), whose frequency value characterizes the source, to be frequency modulated using this low frequency wave a carrier (fO) or high frequency wave, to inject on one of the lines of the network the carrier wave modulated successively by the low frequency waves and in that at the level of the reception said process consists in extracting from one of the lines of the carrier wave network (f0) modulated or the continuous train high frequency mowing, to amplify according to a large ratio the carrier wave (fO) modulated and the background noise, to demodulate the carrier wave (f0) to select the low frequency waves and the background noise , amplifying the low frequency waves and the background noise in a large ratio, writing the said waves to reduce the background noise to a level identical to that of the low frequency waves, selecting the said waves by filtering and addressing, if such a low frequency wave is present at this level a signal identical to that present at the terminals of the corresponding source on one of the outputs (a, b, c, d) each corresponding to the sources (A, B, C, D). R2 / System for transmitting and receiving coded information according to the method defined in claim 1 comprising at least one transmitter (4) coupled to a network line (1) and at least one receiver (5) coupled to the same line or to a different line characterized in that the transmitter is constituted by a device for interrogating (7) the sources (A, B, C, D) by communication elements (16) each in relation to one of the sources during the interrogation by adjustable resistors each switched by an organ (16), by an oscillator (?) controlled in voltage successively by the resistors (16) by a high frequency oscillator (8) generating a carrier wave (fO) modulated in frequency by the waves generated by the oscillator (7) and by an output cell connected to one of the lines of the network. R3 / System for transmitting and receiving coded information according to claim 2 characterized in that the receiver consists of an input cell (19), a tuning block (20), by a stage (21) for amplifying the high frequency waves, by a demodulation stage, by a low frequency amplification stage (23) which delivers waves of the square type therefore clipped, to reduce the background noise and said waves to an identical and constant voltage level which that either the voltage of the carrier wave (fO) received, by one or more selective filters (24) each tuned on a single low frequency wave emitted by the transmitter and delivering if this wave is present a tuning overvoltage, by a or several integrators (25) each associated with a filter (25) and by one or more switching members (29) each associated with an integrator (25) controlled by them to deliver to one of the outputs (a, b, c, d,) a signal identical to that present respect ive at the terminals of the sources (A, B, C, D). R4 / Transmission and reception system according to claim  3 characterized in that the receiver is provided with a compress  to clip low frequency waves amplified by  the floor (23).