EP3729689A1

EP3729689A1 - System for transmitting data by means of optical radiation by means of diffusion by power lines and associated method

Info

Publication number: EP3729689A1
Application number: EP18782794.4A
Authority: EP
Inventors: Alessandro Pasquali
Original assignee: Slux Sagl
Current assignee: Slux Sagl
Priority date: 2017-09-08
Filing date: 2018-09-10
Publication date: 2020-10-28
Also published as: WO2019049090A1

Abstract

A method for diffusing electronic data by means of an optical radiation, said method comprising: - a step of creating a data signal (s(t)) by means of the introduction and/or modulation thereon of electronic data; - a step of injection or cabled transmission of said data signal (s(t)) on a power network (400) of at least part of a building comprising at least one pair of power supply cables (F, N) electrically isolated from each other, wherein said injection or cabled transmission step occurs on a first point (399) of said power network; - a step of diffusing said data signal (s(t)) on said power network (400) of said at least part of building; - a step of receiving said data signal at a second point (401 ) of said power network of said at least part of said building, said second point being separated with respect to said first point (399); - a step of modulating an optical radiation (108) generated by at least one first optical transmitting module (199) by means of said data signal (s(t)), wherein, in said modulation, said data signal (s(t)) acts as modulating signal, wherein said first optical transmitting module (199) is installed at said second point with a cabled connection on said power network (400).

Description

SYSTEM FOR TRANSMITTING DATA BY MEANS OF OPTICAL RADIATION BY MEANS OF DIFFUSION BY POWER LINES AND ASSOCIATED METHOD

FIELD OF THE INVENTION

The present invention relates to the field of the transmission of optical radiation and, in detail, it relates to a system for transmitting data by means of optical radiation by means of diffusion by power lines. The present invention also relates to an associated method for diffusing data. BACKGROUND ART

The use of the electromagnetic spectrum in the field of radio frequencies for the transmission of electronic data, such as, for example, images or audio, is known. The transmission of electronic data on radio channels requires the allocation of a specific channel for each transmission, which cannot be shared, unless multiplexing techniques are employed.

The widespread diffusion of wireless transmissions for diffusing electronic data in broadcast mode, in simulcast mode or with transmissions selectively dedicated to a portion of the users, especially when observing the increase in the volumes of electronic data to be exchanged which has developed in the last few years, quickly saturated the radio channels previously available, forcing the technological community to search for new radio resources, i.e., bands of frequency, at ever higher frequencies, until reaching the microwave spectrum, to allow the transmission of electronic data on radio channels by employing broadband. A typical example are the radio transmission backbones for mobile phone signals, DAB radios, high- definition television signals, which use bands of frequency in the microwave region to have a plurality of adjacent channels, each of which having sufficient bandwidth for the type of transmission required.

The massive use of wireless radio transmission for transmitting electronic data has raised several problems. A first problem is that radio transmissions often use radio channels which are overlapped or, in any case, interfering with the transmission spectra of adjacent channels, or with other sources of interference geographically allocated in a position different with respect to those of interest.

The use of radio transmissions at very high frequencies is also subject to a considerable atmospheric absorption, the latter being, in fact, substantially increasing as the frequency in the radio frequency spectrum increases; consequently to transmit electronic data on broadband at very high frequencies, it is typically necessary to employ significantly high transmission powers.

Furthermore, the use of particularly high radio frequencies especially for close transmissions and for consumer applications is currently the subject of debate in relation to harmfulness to health.

Currently, to diffuse data on a wireless channel, radio transmissions are conventionally employed, which allow the signal on which said data are transmitted to pass through the physical barriers of an apartment - walls, floors - without the need for wiring. The most typical example of such types of transmissions is that given by WiFi networks, where electronic data are transmitted from a modem or access point to further wireless modems installed on board the various electronic devices which are employed daily by users.

The use of so-called "power lines" is also known, i.e., those technological applications for the transmission of electronic data which use electricity power supply and distribution cables already arranged in buildings as transmission mediums. In "power lines", the electronic data is transmitted by overlapping an electrical signal with a significantly higher frequency with respect to the frequency - typically 50 Hz or 60 Hz, depending on the country - of the alternating mains voltage. The separation of the electrical signal which carries the data of interest with respect to the mains voltage occurs by means of filtering and separating the frequencies used.

The Applicant has observed that for diffusing electronic data, the use of "power lines" does not completely solve the problem of the diffusion of electronic data within the home environment or more generally in a building. In fact, "power line" technology allows the transmission of data precisely on a transmission medium made by electricity transport cables, and, therefore, practically up to the wall sockets which are typically deployed in the building. However, if the users want to receive wireless data, without being connected or close to a wall, they would still need a wireless connection, which nowadays is conventionally realised via radio. Otherwise, the user must connect to the wall socket a "power line" technology device, which is powered by means of the mains voltage and conventionally has a data transmission output which in most cases is either radio or cabled, preferably on a standard RJ45 LAN connection. When transmitting data inside of a building without the use of radio signals in a free environment and without the use of cabled connections - in particular, outside the walls - both conventional WiFi networks and "power line" networks are ineffective.

It is the object of the present invention to describe a system and a method for diffusing electronic data by means of optical radiation diffused by means of power line transmission, which contribute to solving the drawbacks described above.

SUMMARY OF THE INVENTION

It is a first object of the present invention a method for diffusing electronic data by means of an optical radiation, said method comprising:

- a step of creating a data signal (s(t)) by means of the introduction and/or modulation thereon of electronic data;

- a step of injection or cabled transmission of said data signal on a power network (400) of at least part of a building comprising at least one pair of power supply cables (F, N) electrically isolated from each other, in which said injection or cabled transmission step occurs on a first point (399)of said power network;

- a step of diffusing said data signal (s(t)) on said power network of said at least part of building;

- a step of receiving said data signal at a second point (401 ) of said power network of said at least part of said building, said second point being separated with respect to said first point (399);

- a step of modulating an optical radiation (108) generated by at least one first optical transmitting module (99) by means of said data signal (s(t)), in which, in said modulation, said data signal acts as modulating signal, in which said first optical transmitting module (99) is installed at said second point (401 ) with a cabled connection on said power network (400).

According to a further non-limiting aspect, said cabled connection on said power network (400) of said at least one first optical transmitting module (99) is a connection in which said optical transmitting module (99) is physically connected to said pair of power supply cables (F, N) electrically isolated from each other.

According to a further non-limiting aspect, said method comprises a step of receiving said optical radiation (108) by at least one first optical receiving module (199), comprising at least one demodulating stage (201 ), or optical demodulating stage, in which it demodulates said optical radiation to extract at least one replica of said data signal (s(t)).

According to a further non-limiting aspect, on said pair of power supply cables (F, N) electrically isolated from each other a mains voltage (v(t)) is present and/or said pair of cables (F, N) is configured to transmit a mains voltage (v(t)) simultaneously, and/or overlapping, said data signal (s(t)).

According to a further non-limiting aspect, a step of filtering an electrical signal including said data signal (s(t)), and/or of filtering said data signal (s(t)) from the mains voltage is present, in which said step of filtering operates a frequency selection centred on a predetermined band of frequencies, which is separate from the band of frequencies in which said mains voltage (v(t)) lies, and/or in which, through the step of filtering, a frequency selection centred on a predetermined band of frequencies is controlled, said predetermined band of frequencies being separate from the band of frequencies in which said mains voltage (v(t)) lies.

According to a further non-limiting aspect, said step of modulating, is an amplitude modulating step.

Alternatively, according to a further non-limiting aspect, said step of modulating is a frequency modulating step.

Still alternatively, according to a further non-limiting aspect, said step of modulating is a pulse width modulating step.

Still alternatively, the step of modulating is a hybrid modulating step, in which the modulation comprises an amplitude modulation and a frequency modulation.

According to a further non-limiting aspect, said step of modulating is, or comprises, a step of varying the polarization angle of the optical radiation emitted by a photoemitter (100) of said first optical transmitting module (99).

Still alternatively, according to a further non-limiting aspect, said step of modulating is a step of modulating comprising:

- a first step of modulating the amplitude of said data signal (s(t)) optionally by means of an AM modulator (102), in which, following said amplitude modulating step, an intermediate signal (s2(t)) is generated, of which said data signal (s(t)) is a modulating signal;

- a second step of modulating the frequency of said intermediate signal (s2(t)) optionally by means of an FM modulator (103), in which, following said frequency modulating step, a voltage or current pilot signal (v7(t), i7(t)) is generated; - a step of adjusting the radiation intensity lr(t)) of said optical radiation (108) emitted by at least one photoemitter (100) by means of said pilot signal (v7(t), i7(t)).

According to a further non-limiting aspect, said step of modulating an optical radiation is executed by means of an optical transmitting module (99) integrated in a body of a lighting device (99c).

According to a further non-limiting aspect, the lighting device (99c) is a lamp, or light bulb, preferably a LED lamp or light bulb.

According to a further non-limiting aspect, in said step of adjusting the radiation intensity, the radiation intensity (lr(t)) is made variable according to said pilot signal, and comprises a first continuous part (I), which is independent from said pilot signal, and a second part which is variable over time as a direct function of said pilot signal (v7(t), i7(t)).

According to a further non-limiting aspect, said part which is variable over time as a direct function of said pilot signal (v7(t), i7(t)) is less in absolute value than the absolute value taken on by said first continuous part (I).

According to a further non-limiting aspect, said step of modulating an optical radiation comprises activating a photoemitter (100) of said optical transmitting module (99), powering it with said data signal (s(t)) and/or with said pilot signal (v7(t), i7(7)).

According to a further non-limiting aspect, said photoemitter is a broadband bandwidth LED.

According to a further non-limiting aspect, in said step of adjusting the radiation intensity, the radiation intensity (lr(t)) is made variable according to said pilot signal, and in the absence of said pilot signal, and/or if said pilot signal is at least temporarily null, the radiation intensity (lr(t)) is different from zero or comprises a residual component different from zero, in particular, only comprising said first continuous part (I).

According to a further non-limiting aspect, said residual component different from zero comprises and/or coincides with said first continuous part (I).

According to a further non-limiting aspect, said method comprises a step of generating a first reference frequency (fO) for said amplitude modulation.

According to a further non-limiting aspect, said method comprises a step of generating a first reference frequency (fO) for said amplitude modulation and a second reference frequency (fc) for said frequency modulation. According to a further non-limiting aspect, the step of generating said first reference frequency and/or said first and said second reference frequencies is executed by means of powering an AM modulator (102) and/or an AM modulator (102) and a FM modulator (103) with a reference frequency generator (109).

According to a further aspect, a further object of the present invention is represented by an optical transmitting device, comprising:

- at least one photoemitter (100) configured to transmit, in use, a modulated optical radiation (108);

- at least one pair of inputs (99d) for powering at least said at least one photoemitter (100),

- a filtering stage (217) having an own input electrically connected to said at least one pair of inputs (99d), said filtering stage being configured to separate, by means of a frequency selection, a data signal (s(t)) of the electrical type from a mains voltage (v(t)), in use, present on said pair of inputs (99d) simultaneously to said data signal (s(t)), and to produce on an output thereof said data signal

(s(t)) isolated from said mains voltage (v(t));

- a modulating stage (101 ) operatively connected with the output of said filtering stage (217), comprising at least one operative configuration in which it generates an electrical pilot signal (v7(t), i7(t)) for said at least one photoemitter (100) modulated according to a predefined modulation scheme based on said data signal (s(t)).

According to a further non-limiting aspect, said at least one photoemitter (100), said filtering stage (217) and said modulating stage (101 ) are enclosed in a single body.

According to a further non-limiting aspect, said device further comprises a decoupling stage (216) interposed between said pair of inputs (99d) and said modulating stage (101 ) and having inputs directly connected to said pair of inputs (99d), said decoupling stage (216) comprising a voltage transformer.

According to a further non-limiting aspect, said modulating stage (101 ) is an amplitude modulating stage.

Alternatively, according to a further non-limiting aspect, said modulating stage (101 ) is a frequency modulating stage.

Still alternatively, according to a further non-limiting aspect, said modulating stage (101 ) is a pulse amplitude modulating stage. Still alternatively, according to a further non-limiting aspect, said modulating stage (101 ) is a hybrid stage, comprising:

- an input (105) adapted to receive, in use, an electrical signal (s(t)) to be modulated, and, in particular, said data signal (s(t)) of the electrical type, and

- an output (107) transmitting a voltage or current pilot signal (v7(t), i7(t)) towards said at least one photoemitter (100), for which said electrical signal (s(t)), and, in particular, said data signal (s(t)) of the electrical type, represents a modulating signal, where said at least one photoemitter (100) transmits an optical radiation (108) with variable radiation intensity (lr(t)) according to said pilot signal (v7(t), i7(t)).

According to a further non-limiting aspect, between said input and said output of said modulating stage (107), a cascade of a first AM modulator (102) and of a second FM modulator (103) is present, said FM modulator (103) being placed downstream of said AM modulator (102) and having an own output directly connected to the output (107) of said modulating stage (101 ), in which said AM modulator (102) has an input directly connected to said input (105) of said modulating stage and is directly powered by means of said electrical signal (s(t)) to be modulated, and in which said AM modulator (102) has an output on which it generates an intermediate signal (s2(t)) powered at input at said FM modulator (103).

According to a further non-limiting aspect, a piloting stage (104) is further present, for said at least one photoemitter (100) interposed between said output (107) of said modulating stage (101 ) and said at least one photoemitter (100), in which said piloting stage (104) is configured to influence said pilot signal (v7(t), i7(t)) and comprises processing means comprising at least one operative configuration such that said variable radiation intensity (lr(t)) according to said pilot signal comprises a first continuous part (I), independent from said pilot signal, and a second part which is variable over time as a direct function of said pilot signal, in which said part which is variable over time as a direct function of said pilot signal, is less in absolute value than the absolute value taken on by said first continuous part.

According to a further non-limiting aspect, said photoemitter (100) is a semiconductor photoemitter, in particular, a broadband LED photoemitter, optionally, a LED photoemitter of the GaN type or a SLED.

According to a further non-limiting aspect, said photoemitter (100) is a laser. According to a further non-limiting aspect, said modulating stage (101 ) is a hybrid stage, preferably configured to modulate said data signal (s(t)) in amplitude and/or in frequency, comprising:

- an output (107) transmitting a voltage or current pilot signal (v7(t), i7(t)) towards said at least one photoemitter (100), for which said electrical signal (s(t)), and, in particular, said data signal (s(t)) of the electrical type, represents a modulating signal, where said at least one photoemitter (100) transmits an optical radiation (108) with variable radiation intensity (lr(t)) according to said pilot signal (v7(t), i7(t)), and in which a piloting stage (104) is also present for said at least one photoemitter (100), interposed between said output (107) of said modulating stage (101 ) and said at least one photoemitter (100), in which said piloting stage (104) comprises at least one operative configuration such to cause the generation, by said at least one photoemitter (100), of a variable radiation intensity (lr(t)) according to said pilot signal and comprising a first continuous part (I), independent from said pilot signal, and a second part which is variable over time as a direct function of said pilot signal.

According to a further non-limiting aspect, said part which is variable over time as a direct function of said pilot signal, is less in absolute value than the absolute value taken on by said first continuous part.

According to a further non-limiting aspect, in the absence of said pilot signal, and/or if said pilot signal is at least temporarily null, the radiation intensity (lr(t)) is different from zero or comprises a residual component different from zero.

According to a further non-limiting aspect, said intermediate signal (s2(t)), powered at input to said FM modulator (103), is a signal adapted to cause a variation in the instantaneous frequency which said pilot signal (v7(t)), i7(t)) takes on at the output of the FM modulator (103).

According to a further non-limiting aspect, said device comprises at least one stage of generating a reference frequency (109), in which said stage of generating a reference frequency (109) is electrically connected to a reference frequency input of said AM modulator (102) and generates at least one first reference frequency (fO) for said AM modulator. Alternatively to the aforesaid twenty-second aspect, said stage of generating a reference frequency (109) is electrically connected to a reference frequency input of said AM modulator (102) by means of a first output (109f) thereof, and is further electrically connected to a reference frequency input of said FM modulator (103) by means of a second output (109s) thereof.

According to a further non-limiting aspect, said stage of generating a reference frequency (109) generates at least one first reference frequency (fO) for said AM modulator (102) and a second reference frequency (fc) for said FM modulator (103).

According to a further non-limiting aspect, said device further comprises at least one photoreceiver (200) electrically connected to a demodulating stage (201 ), said demodulating stage (201 ) receiving, in use, an electrical pilot signal (v7(t), i7(t)) generated by said at least one photoreceiver (200) and comprising at least one operative configuration in which it generates, on an output thereof, an output replica signal (s'(t)), said output replica signal representing a data signal used to modulate an optical radiation received by said photoreceiver (200).

According to a further non-limiting aspect, said demodulating stage (201 ) is an amplitude demodulating stage.

Alternatively, according to a further non-limiting aspect, said demodulating stage (201 ) is a frequency demodulating stage.

Alternatively, according to a further non-limiting aspect, said demodulating stage is a pulse amplitude demodulating stage.

Alternatively, according to a further non-limiting aspect, said demodulating stage is a hybrid demodulating stage comprising:

- an input (205) adapted to receive, in use, a voltage or current pilot signal (v7(t), i7(t)) modulated and generated by means of a photoreceiver (200) connected thereto and receiving, in use, an even reflected optical radiation (108), and

- an output (207) transmitting an output replica signal (s'(t)) for which said electrical signal (s(t)) represents a modulating signal,

and in which, between said input and said output of said demodulating stage (201 ) a cascade of a first FM demodulator (203) and of a second AM demodulator (202) is present, said FM demodulator (203) being placed upstream of said AM demodulator (202), in which said AM demodulator (202) has an input directly connected to the output of said FM demodulator (203). According to a further non-limiting aspect, said demodulating stage comprises an output electrically connected to a secondary circuit of the decoupler (216).

According to a further non-limiting aspect, said decoupler (216) is a voltage- reducing transformer in which the average voltage on the secondary circuit is less with respect to the average voltage present on the primary circuit.

According to a further non-limiting aspect, a use of the optical transmitting device is described, according to one or more of the aspects described herein, for the transmission of multimedia data signals.

According to a further aspect, it is therefore a further object of the invention an optical radiation system for diffusing data comprising,

- a device for injecting an electrical data signal (s(t)) comprising at least one pair of connectors adapted to be electrically connected on a power network (400), and

- at least one optical transmitting device according to one or more of the preceding aspects.

In particular, according to a further non-limiting aspect, said injecting device is an optical transmitting device according to one or more of the preceding aspects.

For greater clarity, the following definitions apply to the present description. According to the present invention, optical radiation means an optical radiation comprised in the infrared spectrum and/or in the ultraviolet spectrum and/or in the visible spectrum.

According to the present invention, direct optical radiation or direct optical transmission means a transmission of an optical radiation in which between a source or photoemitter and a destination or photoreceiver no optically opaque obstacles are interposed and no reflections are present. In other words, in the direct optical radiation or direct optical transmission, the transmission of the signals occurs with said source or photoemitter and the destination or photoreceiver being within the optical range, i.e., mutually visible.

For the purposes of a better understanding of the present invention, the following definitions also apply:

- "Transparency" means a feature such that the material under examination may allow a radiation, which is incident thereon, to pass along a preferential direction, independently of the attenuation that such radiation undergoes in the passage through said material. - "Infrared" means an electromagnetic radiation which has a wavelength approximately from 0.7 pm to 15 pm.

- "Visible" or "visible spectrum" means an electromagnetic radiation which has a wavelength approximately from 390 to 700 nm.

- "Ultraviolet" means an electromagnetic radiation which has a wavelength approximately from 400 nm to 10 nm.

- "Directive irradiation" or even only "directive", when referred to an optical and/or radio frequency radiation, means a radiation emitted by a radiator in the domain of interest - therefore, optical or radio frequency - in which a sector of the sphere of an otherwise isotropic radiator has a radiated electromagnetic power density which is higher with respect to the remaining sectors.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments and some aspects of the invention are described below with reference to the accompanying drawings, only provided by way of indication and therefore not by way of limitation, in which:

- Figure 1 shows a block diagram of a device in accordance with the invention, operating according to the method described above, in an embodiment thereof, preferably, but not by way of limitation, in the form of a light bulb;

- Figure 2 shows a first alternative and non-limiting solution for the modulator present in the device in accordance with the invention;

- Figure 3 shows a second alternative and non-limiting solution for the modulator present in the device in accordance with the invention;

- Figure 4 shows a third alternative and non-limiting solution for the modulator 101 present in the device in accordance with the invention;

- Figure 5 shows a fourth alternative and non-limiting solution for the modulator present in the device in accordance with the invention;

- Figure 6 shows a more detailed diagram for the fourth alternative and non-limiting solution for the modulator present in the device in accordance with the invention; - Figure 7 shows an alternative and non-limiting embodiment of the device in accordance with the invention in which a modulator and also a demodulator for the optical radiation is present; and

- Figure 8 shows an electrical diagram for the embodiment of Figure 7. DETAILED DESCRIPTION OF THE INVENTION

It is the object of the present invention an optical transmitting device shown in Figure 1 in a non-limiting embodiment thereof. Such device is equipped with at least one photoemitter 100 adapted to transmit, in use, a modulated optical electromagnetic radiation 108, in particular an optical radiation in the visible and/or infrared and/or ultraviolet spectrum. The optical transmitting device, which in a preferred and non-limiting embodiment takes on the form of a light bulb 99 equipped with a body 99 and with a portion 99c adapted to emit an optical radiation, has at least one pair of inputs 99d for powering the photoemitter 100 by means of the electricity coming from the power network of a building. On the domestic power network a data signal s(t) of the electrical type travels, overlapping a mains voltage v(t). Preferably, the inputs 99d are connected on a socket 401 , in turn connected to a power network, preferably, but not by way of limitation, to the domestic power network 400 of an apartment. On such power network, the mains voltage v(t) may be a mains voltage of the continuous or alternating type, characterized in this case by an own carrier frequency. The data signal, in particular, may be a multimedia data signal, i.e., a data signal containing audio and/or video data.

In detail, the photoemitter 100 may either be a consistent photoemitter - by "consistent" meaning a monochromatic photoemitter, as it may be a LASER - or an inconsistent one - by "inconsistent" meaning a photoemitter emitting a polychromatic optical beam, meaning, for example, of white light or of any colour, not distinguished by high spectral purity, such as, for example, a LED diode or a SLED one. Conveniently, in the form of a light bulb, the device object of the invention may comprise a plurality of high-power photoemitters 100 which, advantageously allow to illuminate, for example, a room.

In particular, the Applicant has observed that the LED diodes may be employed even if the use of an extremely high bandwidth is requested, up to ranges of several hundred MHz, for example, up to 800 MHz or 900 MHz. In particular, the Applicant has observed that GaN LED diodes, or broadband diodes such as SLEDs, may be employed in the optical transmitting device described herein. In any case, the use of SLEDs or LEDs, also of the GaN type, allows to reduce costs with respect to the employment of a laser.

Preferably, but not by way of limitation, the optical transmitting device has a filtering stage 217 having an own input electrically connected to the inputs 99d. The filtering stage is configured to separate, by means of a frequency selection, a data signal s(t) of the electrical type from a mains voltage v(t), in use, present on the inputs 99d simultaneously to said data signal s(t), and to produce on an output thereof said data signal s(t) isolated from said mains voltage v(t).

Conveniently, the band of frequencies on which the data signal s(t) is transmitted on the domestic power network 400 is a band of frequencies separate with respect to the band of frequencies on which the electrical signal of the mains voltage v(t) is transmitted; suitably, the selection of an appropriate guard interval between the two bands may be provided for, which advantageously allows an optimization of the filtering and/or prevents, or in any case helps to reduce, the influence of the oscillation of the mains voltage v(t).

The optical transmitting device, which in the embodiment of Figure 1 is identified by means of a light bulb or of an equivalent lighting device, comprises at least one optical transmitting module 99 which comprises the photoemitter 100 and at least one modulating stage 101 .

The modulating stage 101 is operatively connected with the output of the filtering stage 217, comprising at least one operative configuration in which it generates an electrical pilot signal v7(t), i7(t) for the photoemitter 100 modulated according to a predefined modulation scheme based on said data signal s(t).

As shown in the embodiment of Figure 1 , the photoemitter 100, said filtering stage 217 and said modulating stage 101 are enclosed in a single body by virtue of which they may be easily handled.

To ensure the correct decoupling of the data signal s(t) from the mains voltage v(t), which is considerably higher than the data signal itself, the device object of the invention further comprises a decoupling stage 216 interposed between the inputs 99d and the modulating stage 101 having inputs directly connected to said pair of inputs 99d.

According to a first embodiment, shown in Figure 2, the modulator 101 is an amplitude modulating stage. Alternatively, the modulator 101 may be a FM frequency modulating stage (Figure 3) or a pulse amplitude modulating stage (Figure 4).

Still alternatively, as shown in Figure 5, the modulating stage 101 is a stage comprising: - an input 105 adapted to receive, in use, an electrical signal s(t) to be modulated, and

- an output 107 transmitting towards the photoemitter 100 a voltage or current pilot signal v7(t), i7(t), for which the electrical signal s(t) represents a modulating signal.

The modulating stage 101 is a hybrid stage, i.e., it is a stage which realises a hybrid modulation comprising an amplitude modulation and a frequency modulation. The amplitude and frequency modulations are realised in cascade, preferably and not by way of limitation, in the form which is described below. In particular, the Applicant has observed that such hybrid modulation may be advantageously used on broadband bandwidth LED diodes, in particular and not by way of limitation, as those described above.

In accordance with the pilot signal received, the photoemitter 100 transmits an optical radiation 108 with variable radiation intensity Ir (t) according to said pilot signal v7(t), i7(t), and between said input and said output of said modulating stage 107 a cascade of a first AM modulator 102 and of a second FM modulator 103 is present. The FM modulator 103, being placed downstream of the AM modulator 102, has an own output directly connected to the output 107 of the modulating stage 101 .

Advantageously, the Applicant has observed that the use in cascade of an AM modulation followed by an FM modulation for an optical signal allows an optimal diffusion thereof in the environment and a remarkable ease of reception of optical radiations which - in the whole radiation spectrum typical of optical signals as defined above - may be conveniently received and demodulated not only upon direct transmission, but also upon reflected transmission by means of one or more reflections or diffusions by one or more surfaces.

The AM modulator 102 has an input directly connected to the input 105 of the modulating stage and is directly powered by means of said electrical signal s(t) to be modulated. The AM modulator 102 has an output on which it generates an intermediate signal s2(t) powered at input to said FM modulator 103.

Preferably, but not by way of limitation, a piloting stage 104 interposed between the output 107 of the modulating stage 101 and the photoemitter 100 is also present. Advantageously, the piloting stage 104 is configured to influence said pilot signal v7(t), i7(t) and comprises processing means which operate so that, in at least one operative configuration, the variable radiation intensity lr(t), in accordance with the pilot signal, comprises a first continuous part I, independent of said pilot signal, and a second part which is variable over time, as a direct function of the pilot signal itself. In the absence of the pilot signal, or if the pilot signal is at least temporarily null, the radiation intensity lr(t) is different from zero or comprises a residual component different from zero. Such residual component, may comprise and/or coincide with the first continuous part I; in particular, such continuous part may take on the function of mere illumination, and therefore be derived from the mains voltage (v(t)). Preferably, but not by way of limitation, the part which is variable over time as a direct function of said pilot signal, is less in absolute value than the absolute value taken on by said first continuous part. In practical terms, this translates into the fact that, at least during the signal modulation, i.e., under active use in transmission conditions, the photoemitter 100 is never completely switched off.

In particular, the intermediate signal s2(t) powered at input to the FM modulator 103 is a signal adapted to cause a variation in the instantaneous frequency which the pilot signal v7(t), i7(t) takes on at the output of the FM modulator 103.

In order to generate a frequency useful for the FM modulation, the modulator 101 also comprises a stage of generating a reference frequency 109, electrically connected to a reference frequency input of the AM modulator 102, and generates at least one first reference frequency fO for the AM modulator. Alternatively, as shown in Figure 6, the stage of generating a reference frequency 109 is electrically connected to a reference frequency input of said AM modulator 102 by means of a first output 109f thereof, and is further electrically connected to a reference frequency input of said FM modulator 103 by means of a second output 109s thereof.

When the carrier frequencies of the AM component are to be separated from the FM component, the stage of generating a reference frequency 109 generates at least one first reference frequency fO for said AM modulator 102 and a second reference frequency fc for said FM modulator 103.

At least parts of the modulating stage, in particular of the AM modulator, the FM modulator and/or the pulse width modulator, may be realised as hardware or with a mixed hardware software structure or again as SDR, therefore purely as software, without such difference constituting a limitation for the purposes of the present invention.

Optionally, alternatively or in addition to the preceding modulations, the optical transmitting module may be configured to transmit an optical radiation comprising a variation of the polarization angle of the optical radiation emitted by the photoemitter 100, in particular - although, not by way of limitation - so that the variation over time of the polarization angle occurs according to the data signal s(t) and/or to the pilot signal.

As shown in Figure 7, the device object of the invention may further comprise a demodulator comprising a photoreceiver 200 electrically connected to an optical receiving module 199. Preferably, but not by way of limitation, also the optical receiving module 199 is integrated in the same body in the which the modulator and the inputs 99d are integrated.

The optical receiving module 199, is configured to demodulate the optical signal received by the photoreceiver 200 and to transmit on an output thereof a replica electrical signal s'(t).

In a particular non-limiting embodiment, the optical receiving module 199 may integrate an AM demodulator. Alternatively, in a further non-limiting embodiment, the optical receiving module 199 may integrate a FM or PWM demodulator, in particular, a phase demodulator which is configured and/or devised to realise a frequency demodulation. Still alternatively, the optical receiving module 199 may integrate a hybrid demodulator of amplitude and frequency modulated signals, i.e., a demodulator adapted to realise a frequency demodulation and an amplitude demodulation.

In particular, the photoreceiver 200 is electrically connected to a demodulating stage 201 , and, in use, receives an electrical pilot signal v7(t), i7(t) generated by the photoreceiver 200. In a specific operative configuration, the demodulator 201 generates on an output thereof an output replica signal s'(t) which represents a data signal used to modulate an optical radiation receive by the photoreceiver 200.

Still alternatively, the demodulating stage is a hybrid demodulating stage comprising:

- an input 205 adapted to receive, in use, a voltage or current pilot signal v7(t), i7(t) modulated and generated by means of a photoreceiver 200 connected thereto and receiving, in use, an even reflected optical radiation 108, and - an output 207 transmitting an output replica signal s'(t) for which the electrical signal (s(t)) represents a modulating signal,

and in which, between the input and said output of the demodulating stage 201 a cascade of a first FM demodulator 203 and of a second AM demodulator 202 is present.

In particular, as shown in Figure 8, the FM demodulator 203 is placed upstream of the AM demodulator 202, which, in turn, has an input directly connected to the output of said FM demodulator 203.

The Applicant has surprisingly observed that the hybrid demodulating stage as described above is particularly adapted to receive with a correct demodulation of the modulating signal, optical radiations 108 received indirectly, by means of multiple reflections or even diffusions, without a direct optical path being present between the radiation source and the photoreceiver 200.

The demodulating stage comprises an output electrically connected to a secondary circuit of the decoupler 216.

The decoupler 216, preferably, but not by way of limitation, is a voltage- reducing transformer equipped with a primary connected to the inputs 99d of the device object of the invention and to a secondary connected to the optical modulating stage 99 and, when present, to the optical demodulating stage 199.

When such decoupler 216 is a voltage-reducing stage, the average voltage on the secondary circuit is less with respect to the average voltage present on the primary circuit. By virtue of this feature, it is possible to realise a device particularly safe to use and handle.

Advantageously, the connection of the decoupler 216 both to the optical transmitting module 99 and to the optical receiving module 199 allows the device object of the invention not only to become a means of diffusion of a modulated optical radiation, but also to become a device which allows the injection on the domestic power network 400 of a data signal received starting from a further signal, in turn, of the optical type.

When transmitting electronic data by means of an optical radiation employing the device of the invention is desired, a first step of the method for diffusing electronic data by means of optical radiation, which is also the object of the invention, comprises, first of all, a step of creating a data signal s(t) by means of the introduction and/or modulation thereon of electronic data. Preferably, but not by way of limitation, such electronic data are electronic data of an audio signal. The data signal s(t) is therefore, preferably but not by way of limitation, an electrical data signal.

The data signal s(t) is then injected on the domestic power network 400 by means of a known procedure. In particular, the injection of the data signal s(t) on the domestic power network 400 may occur by means of a cabled transmission. Following the injection of the electrical signal on the cabled network, the method which is the object of the invention comprises a diffusion of the data signal s(t) in the form of a preferably voltage signal, along the whole domestic power network 400, so that it diffuses to one or more electrical current sockets 401 electrically connected to the domestic power network, thus overlapping the electric voltage present on the domestic power network.

In particular, when the domestic power network is of the single-phase type, two electrical conductors are present, identified in Figure 1 with the references F, N, on which the data signal is transported. The data signal s(t) is thus transported from a first point 399, which corresponds to the injection point, to at least a second point which corresponds to the electrical current socket 401 .

The method further comprises a step of receiving the data signal s(t), overlapping the voltage or current signal, at the electrical current socket 401 , and, by means of a connection of the known type, is transmitted to the inputs 99d of the device or light bulb 99c object of the invention.

Here, the electrical signal is first subjected to a filtering step by means of the decoupling stage 216 preferably realised by means of the previously described transformer, together with the filtering stage 217. The purpose of these two stages is to lower the voltage at which the modulator and the demodulator cooperate and, furthermore, to separate the useful component of the data signal s(t) from the 50/60Hz component typical of the mains voltage of domestic appliances. When the mains voltage v(t) is not alternating, but on the contrary is a continuous voltage, such filtering stage 217 may not be present.

Subsequently, the method provides for a step of modulating an optical radiation 108 generated by at least one first optical transmitting module 99 by means of the data signal s(t) thus extracted from the voltage signal present on the domestic power network 400. In particular, the data signal acts as a modulating signal for the aforesaid optical radiation. The modulation of the optical signal follows, in particular, the predefined modulation scheme described above.

In the method object of the present invention, the connection cabled on said power network of said at least one first optical transmitting module is a connection in which the optical transmitting module 99 is physically connected to the pair of power supply cables electrically isolated from each other.

When the device which is the object of the present invention has both the optical receiving stage and the optical transmitting stage 199, 99, the method which is the object of the present invention also has a step of receiving an optical radiation 108 by at least one first optical receiving module 199 comprising at least one demodulating stage 201 , in which it demodulates said optical radiation to extract at least one replica of said data signal s(t).

The method object of the invention also comprises a step of filtering said electrical signal from the mains voltage v(t), in which said step of filtering operates a frequency selection centred on a predetermined band of frequencies, separate from the band of frequencies in which said mains voltage v(t) lies. Such step of filtering is operatively carried out by the filtering stage 217.

If present, the step of receiving said optical radiation 108 is operatively followed by a demodulating step according to a predefined demodulation scheme, which preferably, but not by way of limitation, follows the modulation scheme which is also operatively used for modulating the data signal s(t). By means of the demodulation step according to the predefined demodulation scheme, a replica data signal s'(t) is generated, which is transmitted, and optionally, but not by way of limitation, injected in the domestic power network 400.

The step of receiving the optical radiation 108 by the device object of the invention, if equipped with an optical demodulating stage as previously described, is therefore followed by a step of injection of the replica signal s'(t) of the data signal s(t) with which the optical radiation 108 received has been modulated, within the domestic power network 400. At the injection step, the replica signal s'(t) is first passed into the secondary stage of the decoupler 216, from which it passes to the primary stage of the same decoupler, thus being capable of being injected and diffused on the domestic power network.

The Applicant also found that in the injection step, through the passage from the secondary to the primary of the decoupler 216, it is possible to increase the voltage value of the replica signal s'(t) injected in the domestic power network. In doing so, the energy request which is demanded for the "creation" of the replica signal s'(t) is moderate, and at the same time, following the step of voltage increase which is brought about by the passage of the replica signal s'(t) from the secondary to the primary of the decoupler, it is advantageously possible to optimize the noise immunity of the system. In fact, the injection on the network of a replica signal s'(t) which is voltage-increased by virtue of the passage from the secondary to the primary of the decoupler, makes the signal/noise ratio greater with respect to what it would have been if the replica signal s'(t) was not voltage-increased, allowing a diffusion of the replica signal s'(t) correctly distinguishable with respect to the electrical noise, on domestic power networks 400 of remarkable size, as well as on public networks on which the system may be installed, even in the presence of strong electromagnetic disturbances.

It is therefore a further object of the invention an optical radiation system for diffusing data comprising:

- an optical transmitting device according to the invention, operatively connected to the domestic power network 400 at the aforesaid second point by means of the inputs 99d thereof, and

- a device for injecting a data signal s(t), which, on the basis of electronic data, transmits, and more precisely injects, the data signal s(t) itself on the domestic power network 400.

Conveniently, the device for injecting the data signal s(t) may advantageously be a particular embodiment of the optical transmitting device according to the invention, if equipped with an optical receiving stage. In such case, conveniently, the inputs 99d, due to the presence of the connection between the output 207 of the demodulator and the decoupling stage 216, also become terminals for the connection to the domestic power network 400, and advantageously allow to transform the aforesaid device into a means suitable for transmitting on the domestic power network 400 a data signal, in particular, a data signal received from another optical radiation. The Applicant has observed that such configuration is particularly advantageous if the domestic power network 400 is realised in the form of several subnets, which, although electrically connected to one another, are decoupled so that a data signal passing therethrough may not diffuse widely on all sub-networks. Equally, the Applicant has observed that such configuration is particularly advantageous if, with the system as described, connecting a plurality of electrically isolated power networks - from the point of view of data diffusion - is desired. In particular, if in the system object of the invention the modulations and demodulations are of the hybrid type - therefore with AM and FM modulation cascade in transmission and FM and AM in reception, in accordance with the features previously exposed - the system becomes particularly adapted to transmit electronic data by means of optical radiation between two isolated power networks or electrical sub-networks, in environments in which no direct transmission of an optical radiation between a receiver and a transmitter is possible.

The advantages of the device and of the method described herein are apparent in the light of the above description. The diffusion of data signals advantageously occurs without the use of radiation systems employing radio waves. When the optical radiation 108 diffused by the photoemitter 100 is confined in a closed domestic environment, without the possibility of diffusion outside, it would not be possible for a fraudulent listener to receive and therefore to decode the data signal modulated through the radiation if not through a physical presence of a suitable receiving device directly in the environment where the optical radiation 108 is diffused. The suitability of the device object of the invention for transmitting multimedia data allows the use thereof as a device for the diffusion or streaming of audio/video streams, generated from sources available inside, or in any case close to, the environment where the device is placed or, alternatively or in combination thereof, remotely retrieved.

Furthermore, when an infrared or ultraviolet radiation is employed in the system described herein, such radiation does not interfere with the common radiation typically emitted by the light bulbs.

The device object of the invention may be applied in environments where the atmosphere is at risk of explosion, since optical radiations, unlike non-ionizing radio frequency radiations, pose fewer risks of ignition of such atmosphere.

It is finally apparent that additions, modifications or variations obvious to a person skilled in the art may apply to the object of the present invention, without thereby departing from the scope of protection provided by the accompanying claims.

Claims

1 . A method for diffusing electronic data by means of an optical radiation, said method comprising:

- a step of injection or cabled transmission of said data signal (s(t)) on a power network (400) of at least part of a building comprising at least one pair of power supply cables (F, N) electrically isolated from each other, wherein said injection or cabled transmission step occurs on a first point (399) of said power network;

- a step of diffusing said data signal (s(t)) on said power network (400) of said at least part of building;

- a step of modulating an optical radiation (108) generated by at least one first optical transmitting module (99) by means of said data signal (s(t)), wherein, in said modulation, said data signal (s(t)) acts as modulating signal, wherein said first optical transmitting module (99) is installed at said second point (401 ) with a cabled connection on said power network (400).

2. A method according to claim 1 , wherein the cabled connection on said power network (400) of said at least one first optical transmitting module (99) is a connection wherein said optical transmitting module (99) is physically connected to said pair of power supply cables (F, N) electrically isolated from each other.

3. A method according to claim 1 or to claim 2, wherein a step of receiving said optical radiation by at least one first optical receiving module (199) is present, comprising at least one demodulator stage (201 ) in which it demodulates said optical radiation to extract at least one replica of said data signal (s(t)).

4. A method according to any one of the preceding claims, wherein a step of filtering an electrical signal including said data signal s(t), and/or said data signal (s(t)) from the mains voltage (v(t)) is present, wherein said step of filtering operates a frequency selection centred on a predetermined band of frequencies, which is separate from the band of frequencies wherein said mains voltage (v(t)) lies, and/or wherein, through the step of filtering, a frequency selection centred on a predetermined band of frequencies is controlled, said predetermined band of frequencies being separate from the band of frequencies in which said mains voltage (v(t)) lies.

5. A method according to any one of the preceding claims, wherein said step of modulating is an amplitude modulating step and/or a frequency modulating step and/or a pulse width modulating step and/or a hybrid modulating step, wherein the modulation comprises an amplitude modulation and a frequency modulation, and/or wherein said step of modulating is, or comprises, a step of varying the polarization angle of the optical radiation emitted by a photoemitter (100) of said first optical transmitting module (99).

6. A method according to one or more of the preceding claims, wherein said step of modulating is a modulating step comprising:

- a first step of modulating the amplitude of said data signal (s(t)), optionally by means of an AM modulator (102), wherein, following said amplitude modulating step, an intermediate signal (s2(t)) is generated, of which said data signal (s(t)) is a modulating signal;

- a second step of modulating the frequency of said intermediate signal (s2(t)), optionally by means of an FM modulator (103), wherein, following said frequency modulating step, a voltage or current pilot signal (v7(t), i7(t)) is generated;

- a step of adjusting the radiation intensity of said optical radiation (108) emitted by at least one photoemitter (100) by means of said pilot signal (v7(t), i7(t)).

7. A method according to any one of the preceding claims, wherein the step of transmitting the optical radiation is executed by means of said first optical transmitting module (99) integrated in a body of a lighting device (99c), said lighting device (99c) being preferably a lamp, or a light bulb, in particular, a LED lamp or light bulb.

8. A method according to claim 6, wherein in said step of adjusting the radiation intensity, the radiation intensity (lr(t)) is made variable according to said pilot signal, and comprises a first continuous part (I), which is independent from said pilot signal, and a second part which is variable over time as a direct function of said pilot signal (v7(t), i7(t)).

9. A method according to claim 8, wherein said part which is variable over time as a direct function of said pilot signal (v7(t), i7(t)) is less in absolute value than the absolute value taken on by said first continuous part (I).

10. A method according to claim 6 or to claim 8 or 9, wherein in said step of adjusting the radiation intensity, the radiation intensity (lr(t)) is made variable according to said pilot signal, and in the absence of said pilot signal, and/or if said pilot signal is at least temporarily null, the radiation intensity (lr(t)) is different from zero or comprises a residual component different from zero.

1 1 . A method according to claim 10, wherein said residual component different from zero comprises and/or coincides with said first continuous part (I).

12. An optical transmitting device, comprising:

- a filtering stage (217) having an own input electrically connected to said at least one pair of inputs (99d), said filtering stage being configured to separate, by means of a frequency selection, a data signal (s(t)) of the electrical type from a mains voltage (v(t)), in use, present on said pair of inputs (99d) simultaneously to said data signal (s(t)), and to produce on an output thereof said data signal (s(t)) isolated from said mains voltage (v(t));

13. A device according to claim 12, wherein said at least one photoemitter (100), said filtering stage (217), said modulating stage (101 ) are enclosed in a single body.

14. A device according to claim 13, further comprising a decoupling stage (216) interposed between said pair of inputs (99d) and said modulating stage (101 ) and having inputs directly connected to said pair of inputs (99d), said decoupling stage (216) comprising a voltage transformer.

15. A device according to one or more of the preceding claims 12 to 14, wherein said modulating stage (101 ) is a hybrid stage, preferably configured to modulate said data signal (s(t)) in amplitude and/or in frequency, comprising:

- an input (105) adapted to receive, in use, an electrical signal (s(t)) to be modulated, and in particular said data signal (s(t)) of the electrical type, and

- an output (107) transmitting a voltage or current pilot signal (v7(t), i7(t)) towards said at least one photoemitter (100), for which said electrical signal (s(t)), and in particular said data signal (s(t)) of the electrical type, represents a modulating signal, where said at least one photoemitter (100) transmits an optical radiation (108) with variable radiation intensity (lr(t)) according to said pilot signal (v7(t), i7(t)), and wherein a piloting stage (104) is also present for said at least one photoemitter (100), interposed between said output (107) of said modulating stage (101 ) and said at least one photoemitter (100), wherein said piloting stage (104) comprises at least one operative configuration such to cause the generation, by said at least one photoemitter (100), of a variable radiation intensity (lr(t)) according to said pilot signal and comprising a first continuous part (I), independent from said pilot signal, and a second part which is variable over time as a direct function of said pilot signal.

16. A device according to claim 15, wherein said part which is variable over time as a direct function of said pilot signal, is less in absolute value than the absolute value taken on by said first continuous part.

17. A device according to claim 15 or to claim 16, wherein, in the absence of said pilot signal, and/or if said pilot signal is at least temporarily null, the radiation intensity (lr(t)) is different from zero or comprises a residual component different from zero.

18. A device according to claim 17, wherein said residual component different from zero comprises and/or coincides with said first continuous part (I).

19. A device according to any one of claims 12 to 18, wherein said modulating stage (101 ) is a hybrid stage, comprising:

- an input (105) adapted to receive, in use, an electrical signal (s(t)) to be modulated, and

- an output (107) transmitting a voltage or current pilot signal (v7(t), i7(t)) towards at least one photoemitter (100), for which said electrical signal (s(t)) represents a modulating signal, where said at least one photoemitter (100) transmits an optical radiation (108) with variable radiation intensity (lr(t)) according to said pilot signal (v7(t), i7(t)),

and wherein, between said input and said output (107) of said modulating stage, a cascade of a first AM modulator (102) and of a second FM modulator (103) is present, said FM modulator (103) being placed downstream of said AM modulator (102) and having an own output directly connected to the output (107) of said modulating stage (101 ), wherein said AM modulator (102) has an input directly connected to said input (105) of said modulating stage and is directly powered by means of said electrical signal (s(t)) to be modulated, and wherein said AM modulator (102) has an output on which it generates an intermediate signal (s2(t)) powered at input at said FM modulator (103).

20. A device according to one or more of the preceding claims 12 to 19, wherein said photoemitter (100) is a semiconductor photoemitter, in particular, a broadband LED photoemitter, optionally, a LED photoemitter of the GaN type, or a SLED or a laser.

21 . A use of the optical transmitting device according to one or more of the preceding claims 12 to 20, for transmitting multimedia data signals.

22. A system for diffusing data via an optical radiation, comprising, a device for injecting an electrical data signal (s(t)) comprising at least one pair of connectors adapted to be electrically connected on a power network (400), and

at least one optical transmitting device according to one or more of the preceding claims 12 to 20.