WO2020053732A1

WO2020053732A1 - Electric power generator of the energy harvester type, acoustic reception/transmission unit and water supply network comprising a communication network by means of acoustic transmission

Info

Publication number: WO2020053732A1
Application number: PCT/IB2019/057566
Authority: WO
Inventors: Michele CANEPA; Paolo DOMENICHINI; Marco Fasce
Original assignee: Iren S.P.A.
Priority date: 2018-09-11
Filing date: 2019-09-09
Publication date: 2020-03-19

Abstract

Electric power generator of the energy harvester type, acoustic reception/transmission unit and water supply network comprising a communication network by means of acoustic transmission. The electric power generator of the energy harvester type and hydraulically operated comprises a turbine fed by a fluid flow and an alternator whose shaft is dynamically connected to the rotation shaft of the turbine and wherein the impeller has a resting position of non-interference with the fluid flow or of generating minimum noise, An acoustic self-supplied reception and transmission unit preferably comprises at least one generator of the turbine type referred to above and wherein the signal is amplitude modulated and demodulated on an acoustic carrier. A water supply network comprises a communication system to send and receive the data and/or information and/or commands and controls which comprises at least one node or a plurality of nodes consisting of acoustic reception and transmission units according to the aforesaid characteristics and operating as repeaters of data packets encoded with acoustic waves.

Description

IREN S . p . A .

"Electric power generator of the energy harvester type, acoustic reception/transmission unit and water supply network comprising a communication network by means of acoustic transmission".

DESCRIPTION

The present invention concerns an electric power generator of the energy harvester type and hydraulically operated, comprising a turbine fed by a fluid flow and an alternator whose shaft is dynamically connected to the rotation shaft of the turbine .

Hydraulically operated electric power generators are known and are used both in large hydroelectric power plants and in medium and low power plants that are anyhow always combined with relatively important fluid flow rates .

Moreover, in conditions wherein the fluid flow is intended to feed a drinkable water supply network or is the flow present in a branch of a water supply network, the flow rates are generally low and, moreover, undesired fluid flow resistances are generated when using turbines according to the state of the art.

In particular, a problem of the known turbines consists in that of causing a flow resistance due to a reduction of the fluid passage port, also in resting conditions, wherein the impeller is maintained stationary and the hydrodynamic power is not collected from the fluid flow to convert it into electricity. According to a first aspect, object of the present invention is an electric power generator of the energy harvester type and hydraulically operated, comprising a turbine fed by a fluid flow and an alternator whose shaft is dynamically connected to the rotation shaft of the turbine, wherein the turbine has a stator forming a chamber for housing an impeller mounted on the rotation shaft coaxial to said chamber, said chamber having an inlet and an outlet coaxially facing one another and to which an inlet branch of a fluid feeding pipe and an outlet branch of a fluid feeding pipe are connected, whereas the impeller has fluid flow interference members facing radially with respect to the rotation shaft and extending so that to partially penetrate the zone of the chamber crossed by the virtual intermediate connection extension of said two openings , respectively the inlet and outlet, said radial members being shaped and distributed so that, in a relative angular position between the impeller and stator, the radial members do not protrude so as to fall in said virtual connection zone or protrude therein to a lesser extent with respect to the other relative angular positions between the impeller and stator.

Thanks to this configuration, it is possible to easily insert an impeller inside piping, by sectioning the pipe and connecting the two branches thus obtained at the inlet and outlet openings , while, in the resting or no use condition of the turbine, it is possible to position the impeller so that the radial members interfering with the fluid flow by rotating the impeller itself are positioned outside of the fluid flow path or anyhow penetrate the flow to a minimum extent so that not to cause reductions of the passage port or to maintain these reductions very small .

As will become clearer below, this condition is especially important in low flow rate plants with small pipe diameters.

Moreover, providing a turbine with the aforesaid characteristics is also advantageous when acoustic units for detecting potential losses are provided in the water supply network, since the radial members present in the flow generate disturbing noises that can distort the acoustic signals generated by the zones in which the losses occur.

The solution according to the present invention is also advantageous when flow sensors for measuring the flow rate are provided, since the effects of the impeller stopped to rest, i.e. braked in the resting position, on the fluid flow are zero or minimal.

According to an embodiment, it is advantageously provided to provide a motorized drive member of the shaft of the turbine combined with a power source of said drive member and with a drive unit, the member being controlled by the drive unit to bring and stop the impeller to the above defined resting position, and possibly rotating the impeller at the start of a turbine actuating step, in order to bring the radial members to the position of interference with the fluid flow and/or possibly also to bring the impeller to a sufficient number of revolutions to overcome the initial inertia thereof, therefore reaching the steady rotation status.

According to an embodiment, the drive member consists of the alternator itself, which is in the form of an electric motor operating passively or operated by the turbine to which it is dynamically connected, whereas the power source can consist of an electric power accumulator charged and chargeable by the same electric power generated by the generator, the control unit of the motor being configured to supply it the actuating electric power so that to actively control the turbine or the impeller itself.

In an embodiment, it is possible to provide locking means to lock the impeller and which can be of the electric and/or mechanic type, for example a break, and which are also controlled by the control unit of the alternator so that to synchronize with the actuation of the resting or energy generating step .

An embodiment provides a sensor for detecting the position of the impeller of the turbine to identify the resting position, or the position of non-interference with the fluid flow.

According to an embodiment, the turbine can be coupled with the alternator or electric motor, by means of a rotary coupling of the magnetic type.

According to an embodiment variant, the turbine can also be of the volumetric type.

A generator of this type is advantageous, especially to provide the supply of utilities or electrically operated operative units in positions or conditions in which no other type of electric generator is possible. In the context of water supply networks, a very frequent condition is the need to electrically supply operative units, such as pumps or control units arranged underground and for which the generators operated by combustion motors are thus not recommended. In this case, in the presence of flow rates that can ensure sufficient power to be converted, it is possible to generate sufficient electric power to operate the pumps and other utilities. Moreover, the fact that utilities, such as pumps, are not often operated continuously but only at time intervals for example from the need to raise determined amounts of water or fluid to compensate for the level reductions in tanks, must also be considered, thus the power generated must only be sufficient so as to allow to maintain the charge of the batteries of the accumulators and not to provide the power supply to the utilities.

The present invention concerns an acoustic reception/transmission unit to be particularly used in the water distribution network, the unit comprising :

an electroacoustic transmission transducer adapted to be immersed in a fluid and transforming an electric signal into an acoustic signal;

an electroacoustic reception receiver for transforming an acoustic reception signal into an electric signal;

a control unit configured to process the electric reception and transmission signals; an electric power source;

the control unit comprising a demodulation section of an electric reception signal provided by the electroacoustic reception transducer, the section extracting, from said reception signal, an encoding signal of the information transmitted by the modulation of the acoustic frequency carrier; the control unit comprising a modulation section of an acoustic frequency carrier with an information encoding signal .

In an embodiment, the information, i.e. corresponding encoding signal of said information extracted from the reception signal, is provided to the modulation section for the generation of a transmission signal to the electroacoustic transmission transducer and of the acoustic transmission thereof to further reception/transmission units.

According to an embodiment, the information encoded in the encoding signal provided to the modulation section consists of the measurement signals of at least one sensor selected among one or more of the following sensors: level sensors, flow sensors, loss sensors, temperature sensors, viscosity sensors, pressure sensors, flow rate sensors, and other sensors detecting the presence of one or more chemical substances in the fluid and combinations of said sensors, the control unit being provided with one or more doors for said one or more sensors .

Still according to an embodiment, which can be provided in combination with one or more of any of the preceding embodiments and embodiment variants , the information encoding signal extracted from the demodulation section is provided to a communication interface of the control unit, the communication interface transmitting said signal, i.e. said information by means of one or more electromagnetic transmission protocols, both of the cable or wireless type, to a remote station, such as a data collection or management station. Advantageously, according to an embodiment, said acoustic reception/transmission unit can be supplied by means of a direct connection to an electric power network or can be energetically independent and self-supplied since it is provided with one or more electric power generators.

An embodiment provides that said acoustic reception/transmission unit is provided in combination with a generator of the type according to one or more of the preceding embodiments .

In particular, the acoustic reception/transmission unit can consist of a pipe section in which a turbine is mounted, said pipe having an inlet branch connected to the inlet opening of the turbine and an outlet branch connected to the outlet opening of the turbine, an electroacoustic transmission and/or reception transducer being provided in each of the two inlet and outlet branches, preferably a reception transducer and a transmission transducer in both said inlet and outlet branches .

Obviously, the turbine, as a drive member of the alternator for the electric generation, can be provided alternatively or in combination with one or more further autonomous electric power sources, such as wind generators, generators with internal combustion motors, photovoltaic generators and others .

According to an advantageous embodiment, which allows to properly extract the information from the encoding signal modulated on the acoustic carrier, the invention provides that the modulation/demodulation sections are of the amplitude modulation type.

As will become clearer in the following description of a detailed example, the amplitude modulation allows to overcome the difficulties generated by an effect of several delays of the data packets transmitted for example by means of frequency modulation or FSK or other, due to a so-named "multipath fading" effect.

In particular, the invention provides that the demodulation section and the modulation section operate at mutually synchronized time intervals relative to the transmission and reception.

According to an embodiment, the modulation and demodulation sections comprise a GPS module and a local clock, the local clock being synchronized to the coordinated universal time of the GPS signal .

The reception/transmission unit comprises a receiving section with a first bandpass filter centered on the frequency of the carrier, an envelope detector for extracting the demodulated signal .

According to a further characteristic, the demodulated signal is provided to a processing unit which carries out a convolution of the demodulated and sampled signal with a known check signal.

The reception/transmission unit comprises a transmitting section in which the transmission signal is subjected to sampling in the form of data packet comprising a header, a time pause and the negation of said header.

According to an embodiment, the convolution function for validating the decoded data consists of the header itself.

Still according to an embodiment, the reception/transmission unit carries out a check of the data received by means of the convolution thereof with the negation thereof and with the negation of the header contained in the packet transmitted.

The invention thus also concerns a method for the acoustic transmission of data through a fluid, the method providing the modulation and demodulation of data on an acoustic carrier through amplitude modulation .

According to a characteristic, the method provides for synchronizing to the GPS coordinated universal time of the receiver and transmitter.

In particular, the method provides for the definition of a time transmission window of the transmission signals and a sampling window of the reception signals, the windows being synchronized to one another according to the GPS coordinated universal time, the transmission signals being encoded in the form of packets with a code based on a differential time synchronization.

According to an embodiment, the sampling window is subdivided in time intervals of one bit that can assume the 0 or 1 logic values corresponding to the signal present or absent status, the sampling signal being frequency filtered with a filter centered at the same frequency of the transmission carrier and the signal being subjected to the extraction of the envelope of the signal frequency modulated and subsequently sampled.

According to a characteristic, the sampling occurs in a reception sampling range.

With reference to the present method, according to an embodiment, the sampling range is greater than the transmission time plus the propagation time of the signal in the fluid, the so-named time of flight, and any shift between the clock of the receiver and the clock of the transmitter.

In an embodiment, the signal is encoded so that to comprise, at a prefixed transmission range, a header followed by a pause and subsequently by the information, followed by the information negation and header negation, the content of the reception signal being extracted by demodulation and subjected to a detecting and validating step of the data frame, comprising the convolution of the entire signal with a function corresponding to the header known for the determination of the maximum and minimum values of the bits from which to determine the logic values 0 and 1 corresponding to the signal present or signal absent status.

Still according to an improvement, the validation of the data is further carried out by checking the information and header contents by comparing them to their negation.

Thanks to the method described above, in addition to effectively eliminating or reducing the Gaussian noise through the use of the bandpass filter centered on the frequency of the transmission carrier and to applying a further denoising step thanks to the envelope detector, it is possible to effectively overcome the signal power infiltration problems of a logic bit value of 1, i.e. corresponding to the presence of the signal at the time of a logic bit value of 0 , i.e. corresponding to the absence of signal obtained thanks to the convolution function with the header known. This convolution step obtains a very strong bit detecting step and effectively reduces the influence of the multipath fading effect, also in conditions in which the pipes are long and where the attenuation of the signal and the multipath fading effect drastically reduce the acoustic coherence and power of the wave packets transmitted and propagating in the fluid.

Object of the invention also is concerns a water supply network comprising at least one pipe connecting the two terminal nodes to, for example, a pumping station downstream of a water collection and distribution tank, the terminal nodes comprising, respectively, at least one transmission unit by means of an acoustic data carrier of at least one sensor associated with said first node and one reception unit of the acoustic transmission signal of said data to said second node, said units being obtained according to one or more of the embodiments or variants described above and/or according to any combination of these embodiments and/or embodiment variants .

An embodiment of the aforesaid water supply network provides that it comprises several nodes comprising operative units with functions relative to the distribution of the fluid and in which, at one or more of said operative units, a reception/transmission unit according to one or more of the embodiments described previously is provided, each of which communicates at least with one or more of said reception/transmission units directly connected to it by means of the fluid inside of a pipe section connecting said reception/transmission unit with a further reception/transmission unit.

It is clear how the present invention allows to integrate and/or transform the operative nodes of a water supply network as far as the distribution of the fluid in nodes of a communication network by transmitting with acoustic waves is concerned.

Further characteristics and improvements are object of the dependent claims.

These and further characteristics and advantages of the present invention will become clearer in the following description of some exemplary embodiments shown in the accompanying drawings, in which:

Figure 1 shows a diagram of a first example of a simplified water plant according to the state of the art .

Figure 2 shows a diagram of the plant of figure 1 according to an embodiment of the invention.

Figure 3 shows a diagram of the plant of figure 1 according to a further embodiment of the invention.

Figure 4 shows a diagram of a section for transmitting data or information by means of acoustic waves and through a fluid.

Figure 5 shows a diagram of a section for receiving data or information by means of acoustic waves and through a fluid.

Figure 6 shows a frame of the wave packet with which the data or information is encoded and transmitted by modulation on a carrier consisting of an acoustic wave and the corresponding packet with which said data or information is received according to an embodiment of the present invention.

Figure 7 shows a diagram of an embodiment of a fluid distribution plant in which there are nodes for receiving/transmitting information modulated on acoustic carrier waves according to an embodiment of the present invention.

Figures 8 to 10 show an embodiment of a microturbine according to the present invention.

Figure 11 shows a block diagram of an embodiment of the drive unit of the microturbine according to the invention.

Figure 12 shows a block diagram of a more detailed embodiment of a reception and transmission unit of the type used in the diagram of figure 7 and in which the presence of a turbine according to figures 8 to 10 and the circuit of the block diagram of figure 11 is further detailed.

The present invention concerns the technical field of acoustic telemetry and the following embodiments show the characteristics of the present invention by way of example and without limitations in the application to the management of water distribution systems.

As will be seen in the following description, this type of technology allows the use of water infrastructures present in the distribution of large wireless sensor networks so that to better understand, monitor and control the water distribution system.

In strict integration with the new Internet of Things technologies, a complex network of wireless sensors operating on acoustic data packets on pipelines constitutes the solution according to the present invention for the monitoring of different functional parameters of the network, such as one or more of the following parameters: the aging of the system, the identification of losses so that to restore them, the measuring of the water flows and of other chemical and physical parameters in parts of the system that cannot still be reached by common communication channels as a result of environmental, technological, energetic and cost-related restrictions .

One of the conditions requested consists in low power consumption, since the electric network is rarely present in the necessary inspection and monitoring points: for this reason, the Energy

Harvesting technologies are involved in increasing the availability and extension of a wireless sensor network applied to the water distribution system.

As will become clearer below, thanks to the different embodiments described by way of example and which show how to implement the general principles described in the introduction of the present description, the digital communication system for acoustic telemetry according to the present invention overcomes a first problem of the known techniques for the acoustic transmission of data packets since it allows to overcome the transmission distance limits which were not overcome in the state of the art.

In the context of the same technical field, the experimental solutions have not provided signal transmitting distances that can be practical for the implementation of units for receiving and transmitting data by means of acoustic waves since these experimental solutions have allowed to reach transmitting distances of a maximum of 120 meters through the pipeline. These solutions are described for example in Joseph KM, Watteyne T, Kerkez B. Awa: Using water distribution systems to transmit data.

Trans Emerging Tel Tech. 2018 ;29 : e3219.

; Garcia Acevedo, R. ,

Lopez Mendez, A., Alvarez Alvarez, E., Gonzalez Suarez, S., Rodriguez Lastra, M. , & Gutierrez Trashorras , A. (2012). Acoustic communications in water pipes: an experimental approach. 1st International Congress Water, Waste and Energy Management, (1), 3-6. Retrieved from

Bacher, C., Palensky, P. , & Mahlknecht, S. (2005). Low cost data transmission via metallic solids for sensor networking. In Proceedings - IEEE 2005 International Conference on Emerging Technologies, ICET 2005 (Vol . 2005, pp. 193-198).

Figures 1 to 3 show the principle of the present invention with reference to a very simple application example related to communication in the management of the mountain water distribution system.

In mountain villages, the water distribution occurs with the water falling from a remote storage station 100 with a tank 101 that is arranged at a predetermined altitude with respect to the utilities to be serviced and which can be supplied by a source of water at a higher altitude, for example originating from a mountain source or at a lower altitude than the tank 101 of the storage station 100, such as for example water wells 108. In this case, the water is collected by a pump 107 of a pumping station 103 and transported, i.e. pushed to a higher altitude than the storage station 100, i.e. than the tank 101.

The water tanks 101 can further be of different categories, among which two main categories can be defined:

Large tanks to service relatively large villages, having the following characteristics:

- More users serviced

- Generally supplied by means of the electric network ;

- Presence of a disinfection plant (chlorine) ;

- Presence of an instruction alarm system;

- Presence of a closed-ring control of the water level in the tank 101, by measuring the level on the tank 101 by means of a level sensor 109 and by communicating it to the pumping station 103, where it is received by the control unit 106 of the pump 107 for activating or deactivating it depending on the level present in the tank 101.

For this purposes, in this type of plant, a sort of digital communication is generally provided between the remote storage station 100, i.e. the level sensor 109, and the pumping station 103, i.e. the control unit 106 of the pump 107. Typically, these digital communication systems are communications systems with wireless protocols such as GSM or radio.

In some cases , wherein the morphology of the territory is particularly disadvantageous for radio communications, the standard radio communication systems have implementation difficulties, due to the absence of GSM coverage or radio connection. At the current state, alternative solutions were implemented in these cases, such as Internet connections via satellite, increasing management costs and power consumption .

The present invention particularly provides a telemetric connection via acoustic waves for these systems. This system could also possibly be provided in combination with one or more of the currently used systems described above and could also possibly constitute a backup connection in case of a loss of communication or as a more effective means of communication from an energy point of view.

Still according to a further application, the acoustic telemetry system can also be used to detect water losses in the pipes by analyzing the acoustic noise generated by the loss.

The second category of plants comprises small tanks that service small villages, having the following characteristics with respect to the plants described previously:

- Less users serviced

The plant is not serviced by the electric network ;

A small disinfection plant is required, generally supplied by a battery system and a sort of power collecting system (solar, wind, water) ;

- No intrusion alarm system;

No traditional digital communication connection available due to the absence of GSM connection or radio coverage;

Generally, in these plants, the water level of the tank 101 can be controlled by a rudimentary control wherein the operation of the pump is activated by a timer programmed with a predefined triggering period. The shutdown of the pump is instead controlled by an overpressure switch positioned directly in the water pipeline immediately downstream of the pump.

Thus, in known plants, the pump is activated until the pressure switch is set off, due to an impulse caused by the overpressure due to the closing of the valve near the water tank .

This rudimentary control however has big defects :

The overpressure impulses (water hammer) , generated by the automatic level valve on the tank, stresses the piping and the valves, thus leading to water losses.

- The automatic level valve is subject to wear and its progressive malfunctioning leads to greater overpressures in the plant or to a lack of water due to a non-properly synchronized activation of the pump. This leads to greater service costs and water losses .

A wrong estimate of the pumping time and of unusual water consumptions can lead to a lack of water or to further pressure impulses, since there is no way to know the exact level of water in the tank before activating the pump.

The pressure switch itself is subject to wear and its damage leads to the total obstruction of the pump which can in turn involve the combustion of the motor windings of the pump.

As is clear in figure 2, also for these systems, the inventions provides, as a communication line of the signals for measuring the filling level of the tank, the fluid itself in the pipe connecting the pump the tank by means of a connection of the acoustic telemetry type.

A first embodiment of the invention, applied to a plant according to figure 1, is shown in figure 2.

A water level sensor 109 is installed on the remote tank 101 and is connected to a transmitting section 200 that transforms the electric signal of the sensor into a signal of the acoustic type by modulating the information on a carrier consisting of an acoustic wave.

The acoustic transmission section 200 consists in an electronic card that carries out the functions of generating the acoustic frequency carrier and the modulation thereon of the measurement signal of the level sensor 109. The electric signal is transformed into an acoustic wave and transmitted in the fluid by means of an underwater loudspeaker 201, as denoted by 212 in figure 2.

It is possible to provide different types of modulation protocols and acoustic carrier frequencies. As will be clear below, a preferred embodiment provides to use a particular amplitude modulation protocol of the measurement signals of the level sensor 109 on the acoustic frequency carrier.

The pipeline can be of any material and is for example made of 2.5 inch steel. The length can reach about 800-1000 meters and the pipe connects the pumping station 103 downstream of the remote tank 109 for the water upstream of the pumping station 103.

The acoustic reception section consists in an electronic card for extracting the measurement signals of the level sensor 109 by demodulating them from the acoustic reception signal 204 that is acquired by means of a hydrophone 202. The hydrophone 202 is installed on the pipe near the pumping station, near the non-return valve: the transducer is connected to the receiving section 203.

The receiving section 203 communicates the data of the level of the water tank to the control unit

106 of the pump 107 directly or for example by means of a communication interface such as an Ethernet interface. This interface can be of the cabled or wireless type. The measurement signal extracted from the receiving section 203 can also be transmitted with one or more different communication systems of the cabled or wireless type depending on one or more communication protocols to an IoT cloud service that can allow to collect the information in a centralized remote management system, thanks to which it is possible to monitor the operation and conditions of the single plants distributed over the territory from a central station and to possibly provide maintenance and/or repair activities or to control the availability of water present in the various zones to possibly transfer the water from one plant to another thanks to temporary switch-back connections or to the implementation of stable switch-back connections.

Thanks to the forecast of the data transmission system by means of acoustic telemetry, it is also possible to transmit and receive additional monitoring signals such as signals related to chemical or physical parameters detected by sensors and which describe the state of the plant, as well as to transmit and receive anti-intrusion alarm signals, signals on the state of the water disinfection system, on the diagnostics of the piping and on the presence of losses. A variant of the system according to the previous figure 2 is depicted in figure 3.

In this case, one or more electric power generators are associated with the system by means of so-named "energy harvesting" techniques, such as for example photovoltaic panels 303, wind generators 302, turbines 300 operated by the flow of the fluid itself present in the pipes of the plant.

In this case, these devices can be present in any combination or sub-combination between each other and the energy produced is supplied to a storage section 301. According to an advantageous embodiment, a control unit manages the supply of power to the accumulators and possibly the withdrawal thereof from the accumulators towards the utilities.

Thanks to this arrangement, the acoustic telemetry system can be made completely independent both of cabled or wireless communication networks or of the presence of an electric power supply network.

In the absence of a connection to the electric network, the remote system can be supplied through the control unit of the electric power storage section 301, from the batteries of this section.

According to a further characteristic of the present invention, the complete pipeline is comparable to a delimited acoustic channel which imposes a serious distortion on the acoustic signals propagating along the fluid. Thus, this means of communication has many technical complications which make the acoustic transmission considerably difficult to manage .

Firstly, the ambient and site-specific acoustic noise can overwhelm the signal of the data, especially in the 3-30 kHz band which is typically used for the acoustic carrier.

Moreover, the bandwidth is very limited, since it depends on the transmission distance and the speed of sound. With regard to the speed of sound, not only the fluid is relevant, but also the surrounding terrain plays an important role in determining the absorption loss coefficient of the communication channel, which leads to the attenuation of the acoustic signal level propagating along said channel .

Thirdly, the reliability and integrity of the communication channel constituted by the fluid strongly depend on different parameters such as on the geometry of the piping, the temperature gradient and the material of the piping: these aspects create more propagation paths, or "echoes", for the audio packet. This phenomenon is known as "multipath fading," wherein more replications of the signal arrive to the receiver, i.e. to the hydrophone with different delays and with a different intensity, and can cause destructive interference.

According to an embodiment of the present invention, it is provided to use a point-to-point data connection through the water, between a transmitting section and a receiving section.

With reference to figures 2 and 3, the invention allows to carry out a difficult to reach constant monitoring of the level of a water tank, thus allowing the implementation of a closed-circuit pumping system.

In other applications, the digital communication protocol by means of water medium can also make the transmission of other data and of measurements related to the quality of the water, the diagnostics of the plant, the water flow rate measures and the status of the anti-intrusion system possible, so as to improve the availability and reliability of the water plant and of the distribution service.

In an IoT framework, the acoustic telemetry can allow a natural extension for the activities and the monitoring data of the sampling points that were previously impossible to reach.

According to an advantageous embodiment of the present invention, the exchange of data by means of the water medium is made reliable thanks to an acoustic coupling between the transmitting section and the receiving section by means of a synchronous amplitude modulation of the acoustic carrier for which the noise is effectively rejected.

In an embodiment, the transmitting section is shown in the block diagram of figure 4, while figure 5 shows the receiving section and figure 6 shows a frame being transmitted and the relative frame being received, both encoded in compliance with the digital communication protocol according to a preferred embodiment of the present invention.

The transmission is made by exchanging acoustic wave packets, by modulating a carrier with a sinusoidal waveform with fixed frequency. The frequency and amplitude of the sinusoidal signal of the carrier are defined depending on the acoustic characteristics of the concerned pipeline, i.e. along which the transmission is carried out.

The transmitting and receiving sections are advantageously configured so as to allow to digitally set the proper frequency and proper amplitude for each geometry of the pipes, with simple configuration steps that can be carried out thanks to one or more user input/output interfaces selected, alternatively or in combination with one another, among the currently existing interfaces, such as keyboards, display screens, touchscreens, pointing devices, mobile memory unit readers, cabled or wireless connections with the portable units of the user and which are in turn provided with the input/output communication interfaces with the user and which carry out communication software with the transmitting and/or receiving sections.

According to an embodiment depicted in figure 4, the transmitting section consists of a low power microcontroller 403, a digitally programmable bandpass filter 402, a class D audio power stage 401, whose output is connected to an underwater mobile coil loudspeaker 201. The mobile coil loudspeaker 201 is acoustically coupled with the pipeline with a resonant cavity of Helmholtz 400, so that to match the acoustic impedance of the loudspeaker and fluid in which the acoustic wave propagates and thus to maximize the transmitting power of the packet.

The resonant acoustic cavity 400 is mechanically coupled with the pipe so as to minimize the loss of air: in fact, the air bubbles could modify the acoustic characteristics of the propagation means.

The signal of one or more sensors, which are represented in a non-limiting way by the hydrostatic level sensor 406 and the corresponding control electronics 405 in the example, are provided to the microcontroller 403.

With reference to figure 5, the receiving section comprises an underwater hydrophone 202 consisting of a piezoelectric capsule and of an analog amplifier with which it is coupled to the pipeline: the output signal is filtered by a digitally programmed bandpass filter 508 which is tuned in on the same carrier frequency of the transmitter .

The analog voltage signal is thus sent to a programmable gain amplifier 501 and thus to an RMS detector 502 to extract the envelope signal of the modulated sinusoidal wave.

In order to eliminate the undesired ambient noise and to overcome the distortion effect of the packets, due to the "multipath fading" effect, both the transmitting and receiving sections are synchronized at the GPS coordinated universal time.

As is clear in figures 4 and 5, both the transmitting and the receiving sections have a GPS sensor, respectively 404, 504, that is stabilized relatively to the temperature by means of a temperature compensator respectively denoted by 407, 507.

As in the case of the transmitting section, the section is controlled by a low consumption microprocessor 503 also in the receiving section.

The transmission window and the sampling window are synchronized with a common time base. The packet can thus be transmitted with a differential time synchronous encoding, thus allowing a further noise rejection.

Such differential time synchronous encoding provides that, at predetermined time intervals for example once a day, both the transmitting section and the receiving section synchronize their local clock with the GPS coordinated universal time thanks to the GPS module 404, 504 and to the clock with thermal compensation 407, 507. This clock allows an absolute maximum clock variation of 7 ppm, thus leading to a maximum drift of 0.6 s.

The sampling window is divided in intervals of bit time, as denoted by 601 in figure 6 which shows a transmitted signal frame, i.e. a transmitted data packet denoted by Tx and the corresponding frame or data packet received, denoted by Rx, compared to each other on the common time axis. Each bit time Atb interval contains one bit, which can assume a logic value 0 (sinusoidal signal absent) or a logic value 1 (sinusoidal signal present) .

Each packet or frame consists of a known header

602, a successive time pause of predefined length

603, the data to be transmitted (payload) 604, the negative or negation 605 of the data to be transmitted 604 and the negation of the header 606.

As previously described, during reception, the sampled signal goes through a bandpass filter 508 centered at the same frequency of the sinusoidal carrier transmitted. The filtered signal successively goes through an RMS converter 502, which extracts the envelope of the amplitude modulated signal.

The envelope is thus sampled by the ADC of the low power microcontroller 503, starting from the absolute time tO and ending at the tO + ATrx instant.

In order to sample the data transmitted, the sampling range ATrx must be greater than the transmitting period DTc, plus the flight time of the sound wave crosses the water pipeline Atft and the possible time lag between the absolute clock of the transmitting section and the receiving section Ate as defined by the following relation:

ATrx> Atp + Atft + Ate + Atx

The Gaussian broadband noise is significantly reduced by the bandpass filter 508. A further rejection of the noise is obtained thanks to the envelope detector 502, but the envelope signal could still suffer from the distortion of the packets due to the "multipath fading". The consequence of this distortion is a dispersion of the energy of the signal with the logic bit level 1 within the time interval provided for the logic level 0 of a bit.

For this reason, a convolution algorithm is used to detect and validate the content of the data frame.

In an embodiment, such convolution step provides that the complete signal, sampled within the time interval ATrx, is normalized and convoluted with the known header .

The convolution between the sampling signal and the header has a maximum at the beginning of the sampling signal of the header itself : from this sampled header, the algorithm estimates the successive time sub-windows by searching for a logic value 0 or a logic value 1, depending on the signal energy in the time window of one bit Atb.

The minimum and maximum values, calculated by the convolution, are used to discriminate the logic values 0 and the logic values 1 with one another in the time window sequence. This implements an algorithm for detecting very robust bits, which leads to a byte decoding with an optimal signal to noise ratio (SNR) . The robustness of the protocol allows the system to work in a reliable way also on long pipe sections, wherein the attenuation of the acoustic signal and the "Multipath fading" effect significantly reduce the acoustic coherence and the energy of the wave packet .

The validation of the frames is further implemented by controlling the content of the payload, i.e. the data 604 and the known header 602 with respect to the bytes of their negations 605 and 606.

The frame detecting algorithm is carried out on an incorporated linux system 505. With reference to figure 5, it concerns the example of a receiver used in a plant according to figures 2 or 3 and the decoded tank level is transmitted to the control system 106 of the pump 107 (implemented with a PLC) through a cabled or wireless communication channel of any type, for example through an Ethernet communication channel and possible also an IoT cloud service 507 for the remote monitoring and the data analysis .

As already set forth above, an advantageous embodiment provides to combine one or more energy harvesting devices with the reception and transmission unit by means of acoustic waves according to the present invention, among which devices a microturbine that allows to exploit the same water flow in which the communication occurs by acoustic telemetry to supply the communication system is provided.

The invention thus provides to combine a microturbine, which is driven by the fluid flow used at the same time also as a means for propagating the acoustic signals, with the reception/transmission unit according to one or more of the embodiments described above or sub-combinations thereof.

Thanks to this, the invention achieves a self- supplied acoustic receiver and transmitter, directly interfaced with the water pipeline.

A use solution of this type is very advantageous whenever the acoustic reception/transmission unit is used in underground pipelines, where the coverage of the radio signals is made impossible by the attenuation of the ground and where also the further alternative powers, such as photovoltaic power and wind power, are not present to generate electric power .

Also whenever a reception/transmission unit of this type is self-supplied with a microturbine, said unit can be used thanks to the hydrophone present in the receiving section to detect the noise generated by losses and to thus transmit the information to the closest node in turn connected to the IoT.

The turbine itself can also be used as water flow sensor, after a calibration carried out by the regression of the angular speed of the impeller with respect to the known flow measurements .

The combination of information on the noise coming from the acoustic detector of losses with the information on the flow coming from the two adjacent nodes can lead to a precise detection of the volume of the losses.

The present invention thus concerns a transmission and reception unit by means of acoustic waves that is also self-supplied, said unit being provided with at least one energy harvesting device, i.e. with at least one autonomous electric power generator .

According to a first embodiment, the generator is of the type driven by fluid, and is for example a turbine or the like.

Thanks to this embodiment, the self-supplied reception and transmission unit by means of acoustic waves exploits the same fluid used to propagate the acoustic signals as an electric power source.

Such a self-supplied reception/transmission unit is schematically shown in figure 7, in which it is denoted by 700. Figure 7 shows the use of a plurality of said units 700 for implementing a communication network between a data source and a so-named data concentrator, i.e. a terminal communicating with a data collection and management station with functions similar to those previously described for the IoT system.

In this communication network, each self- supplied reception and transmission unit forms a communication node which receives information in the form of data packets transmitted by means of acoustic waves and retransmitted through the fluid of the pipeline associated therewith to a further reception and transmission unit 700 until covering the distance between the data source, for example a sensor or one or more sensors 703, and the master terminal 704 provided with the cabled and/or wireless communication interfaces by means of electromagnetic waves and with one or more communication protocols traditionally used for this type of communications, such as Ethernet, Wifi, radio transmissions and other protocols .

In the embodiment shown, the reception and transmission units 700 constitute a sort of acoustic signal repeater and comprise a turbine 709 provided, at its inlet opening and at its outlet opening, with an inlet union and an outlet union 705, 706 with which the loudspeaker 707 and the hydrophone 708 are respectively coupled. A pipeline connects the single units 700 to each other. Moreover, the loudspeaker 707 and the hydrophone 706 are respectively combined with a transmitting section and a receiving section of the type described according to one or more of the preceding embodiments and which are supplied by an electric power accumulating section, not shown, which is connected to the alternator driven by the turbine 709.

In the example shown, also the master terminal 702 has a unit for connecting to a pipe with which a hydrophone 708, which provides the reception signal to a receiving section according to one or more of the embodiments of those previously described, is acoustically coupled, and which section has a communication unit 704 for communicating with remote management units.

The data source, which can consist of one or more sensors and/or also of a data input terminal, is denoted by 703 and comprises a self-supplied transmission unit consisting of the turbine 709, with the alternator driven by it and with the accumulator for the electric power generated, the turbine being provided with inlet and outlet unions 705, 706 and crossed by the fluid flow, while the loudspeaker 707 connected to the transmitting section receiving the signals to be transmitted to the signal source 703, is acoustically coupled at the fluid flow, i.e. at one of the unions, and modulates the signals on the acoustic carrier, according to what is described in one or more of the preceding embodiments and similarly to what occurs for all the units 700.

Thanks to this data reception and transmission unit by means of acoustic waves and self-supplied, in particular by means of generators that use the fluid itself as a power source, it is possible to implement a communication network completely independent of other networks by using the water supply network only, thus obtaining low implementation costs of the management and monitoring networks of the water supply networks and also considerably making it easier to expand these networks to new communication nodes .

According to an embodiment, said reception and transmission unit can be made bidirectional by providing, on each union 705, 706, a couple consisting of a hydrophone and a loudspeaker and by alternatively activating the hydrophone or loudspeaker depending on the transmission direction of the signal .

As already stated, in addition to operating as a signal repeater, a reception and transmission unit of the type previously described can also have other functions, such as for example detecting losses depending on the noise generated thereby and detected by the hydrophone and, in combination with the presence of the turbine, also measuring the flow rate, in addition to ensuring an effective generation of electric power, the turbine itself must be able to be brought in a resting position, in particular during the communication steps, i.e. of receiving and transmitting, and during the steps of detecting the noise wherein the impeller of the turbine does not interfere with the fluid flow or interferes with said fluid flow to a minimum and negligible extent.

Thus, the invention also concerns a turbine, in particular a microturbine which is particularly adapted for use in a reception and transmission unit or for use in communication by means of acoustic waves according to the present invention and according to one or more of the embodiments previously described.

A hydraulic turbine optimized for the aforesaid uses must have the following characteristics:

- It must have a state in which the impeller of the turbine does not put up resistance to the water flow (zero-head position) .

- In this position, the water flow should pass without disturbances, or pressure drops or without increasing in acoustic impedance.

- The approaching to the zero-head position or of non-interference with the flow should be controlled by a motor coupled with the impeller. Said position is advantageous to transmit or receive acoustic packets and to listen to the noise of losses, by following a predetermined algorithm.

- The control system must allow the impeller to leave the resting position, i.e. of no interference with the fluid, by moving the impeller with the coupled motor, so that to bring the radial elements of the impeller to interfere with the fluid flow and/or possibly also to operate the impeller in a step of accelerating the rotation to a working speed, i.e. to overcome the inertia of the motion thereof and thus to bring the turbine to the working condition so that to extract power from the fluid and recharge the system.

When used in underground pipelines, the turbine must resist against pressure stresses of up to 10 bars.

An embodiment of the turbine according to the present invention is shown in figures 8 to 10. The example concerns a turbine of the non-volumetric type, but can easily also be extended to a turbine of the volumetric type.

According to a first characteristic, the impeller 802 of the turbine is rotatably mounted in the chamber defined by the stator 801. The stator has in a coincident position an inlet opening 804 and an outlet opening 805, which in this case can also be inverted between each other, and which are arranged coaxially and with their axis aligned along a direction perpendicular to the rotation axis of the impeller 802 and tangent to the body thereof and to the cylindrical chamber in which the impeller is housed.

The diameter of the openings is such as the virtual connection between one another is defined by a cylindrical section which remains inside the stator, possibly of the chamber of the stator or partially inside the chamber of the stator and partially sunken in the thickness of the wall of the stator .

The impeller 802 has at least one, preferably a plurality of arched hollows 812 distributed around its axis, whose axis is oriented tangentially to the rotation axis of the impeller 802 itself and which axes are positioned radially spaced from the rotation axis, thus the ends of said hollows 812 do not intersect each other, thus forming intermediate zones in which the impeller has the whole radial extension.

The position of said hollows and the shape thereof is made so that, in a mounted condition of the impeller 802 in the stator 801 and in the angular position in which the axis of a hollow 812 is parallel to the axis shared by the openings 804 and 805 in the stator, said axes coincide to one another and the shape and length size of the hollow 812 completes, on the side facing the impeller, the walls of the openings and of the virtual channel connecting them so that to form a cylindrical and continuous passage section without any reduction of said section, as is clearer in figures 8 and 9.

In the embodiment shown, the impeller has three hollows 812 distributed angularly at 120° one with respect to the other around the rotation axis.

Still according to an advantageous characteristic, the alternator advantageously consists of an electric motor that can be driven and which operates passively in the electric power generation step, it being rotated by the impeller of the turbine.

The motor allows to be operated when the impeller of the turbine must be slowed down and brought in the position of non-interference with the fluid flow, i.e. in the position named "zero-head," as shown in figures 8 and 9.

Moreover, the motor is operated to bring back the impeller outside of the position of non interference, thus making it operative again.

According to a further improvement, the motor, in the step of leaving the resting position, i.e. of non-interference of the impeller, can be controlled to drive the impeller for a certain period of time in which an acceleration ramp at a predetermined rotation speed is provided so that to overcome the initial inertia of the impeller itself and to reach the regime operating step faster.

According to a further embodiment, the motor and the impeller are mechanically coupled with each other, but in order to reduce dispersions due to inertias, the coupling between the motor, i.e. the alternator, and the impeller is of the magnetic type. For this reason, as shown in figure 10, the body of the impeller has an axial extension on which a crown of permanent magnets is mounted coaxial to the rotation axis of the impeller and which cooperate with magnets of the electric motor. In particular, figure 10 shows the housing seats 807 of the single magnets .

Figure 11 shows an embodiment example with which it is possible to implement the operative modes of the turbine as previously described.

The fluid flow goes through the turbine 800 thanks to the unions 901 and 902 respectively coupled with the inlet and outlet mouths 805 and 804. Thanks to the magnetic coupling, the turbine is dynamically coupled with the rotor of the electric motor. A control unit 903 comprising a processor that executes a control program is connected to the motor and receives the electric power generated by it when the motor 900 is not supplied and is rotated by the turbine 800. The control unit manages the supply of the electric signal to the accumulators 904.

The control software can comprise the instructions to control the shutdown of the turbine and the positioning of the impeller in the position of non-interference with the fluid flow, as well as the step of leaving, by the impeller, the position of non-interference and the possible acceleration thereof to the predetermined rotation speed in the initial acceleration ramp whenever provided.

The control can be imparted thanks to a local user interface 906 or an interface communicating with the remote units 907 or the control unit can be programmed to carry out said control functions of the turbine at predetermined time instants. Such instants can be for example synchronized with the transmitting and receiving steps or with the functions for detecting the noise in the pipe so that to detect losses. The synchronization signal can be that of the GPS coordinated universal time thanks to sections similar to those provided for the transmitting and receiving sections. An alternative can provide that the present system is combined with the reception and transmission unit and receives the signal from the same unit, i.e. from the transmitting and/or receiving section of said unit.

When the impeller must be stopped and brought in the resting position, i.e. of non-interference, the control unit activates a section for supplying the electric motor 905 which supplies power to the motor to drive it so that to progressively slow down the impeller of the turbine and to bring it in the position of non-interference and to rotate the impeller in order to leave the position of non interference and possibly to accelerate it according to the predetermined initial ramp.

The position of non-interference can be determined in different ways that can be both the presence of an encoder of the position of the impeller or a sensor of the resting position, i.e. of non-interference and/or also signals of acoustic type linked to the detection of the flow noise through the turbine and generated in presence of an obstacle to the flow itself. When the flow noise detected has a certain waveform pattern corresponding to the condition of non-interference or approaches it in the range of predetermined tolerances, the turbine is stopped and maintained in this position by a possible brake .

The user interfaces 906 and the communication interface 907 for communicating with the remote units can be of any type and can consist of one or more interface devices known to the technician of the field and among which he can choose. Examples of user interfaces are keyboards, displays, pointing devices, touchscreens, printers, input/output interfaces of vocal type or connections to portable devices of the user, which are in turn provided with interfaces and which execute communication applications with a communication terminal of the control unit.

Example of communication interfaces with remote stations are for example cabled communication networks according to different network protocols, wireless communication networks or of the radio type and possibly the same communication network by means of acoustic waves according to one or more of the embodiments of the present invention previously described.

With reference to figure 12, it shows a more detailed scheme of figure 11. The same parts already described in the preceding figures have the same reference numbers.

In the detailed embodiment, the control unit 903 and the functions with the relative sections are shown. The unit consists of a microcontroller and comprises a section for controlling the motor 800, a section for measuring the current, a section for measuring the state of charge of the battery 120. The circuits supplying the motor have a switch 124 which connects the motor alternatively to the supply driver 905 or to the supply chain of the batteries with the power generated by the motor working as alternator, as denoted by the components 123 and 125.

The microcontroller has sections for actuating and controlling the functions of measuring 128 the flow, of measuring the pressure, of extracting the data from the reception signals and of modulating the data on the acoustic carrier, as well as a section for controlling the motor for the non-interference position 129. The aforesaid sections are connected to corresponding sensors or members as shown in the diagram and in particular the receiving and transmitting sections to the hydrophone 708 and to loud speaker 707 and the sections for measuring the flow to a pressure sensor 127, and the section for positioning in a position of non-interference 129 to an encoder 126.

Claims

1. Electric power generator of the energy harvester type and hydraulically operated, comprising a turbine fed by a fluid flow and an alternator whose shaft is dynamically connected to the rotation shaft of the turbine, wherein the turbine has a stator forming a chamber for housing an impeller mounted on a rotation shaft coaxial to said chamber, said chamber having an inlet and an outlet coaxially facing one another and to which an inlet branch of a fluid feeding pipe and an outlet branch of a fluid feeding pipe are connected, whereas the impeller has fluid flow interference members facing radially with respect to the rotation shaft and extending so that to partially penetrate the zone of the chamber crossed by the virtual intermediate connection extension of said two openings, respectively the inlet and outlet ones,

characterized in that said radial members are shaped and distributed so that, in a relative angular position between the impeller and stator, the radial members do not protrude so as to fall in said virtual connection zone or they protrude therein to a lesser extent with respect to the other relative angular positions between the impeller and stator.

2. Generator according to claim 1, characterized by being used to measure the fluid flow rate.

3. Generator according to claim 1 or 2, characterized by being provided in combination with a motorized drive member of the impeller of the turbine, combined with a power source of said drive member and with a drive unit, the member being controlled by the drive unit to bring and stop the impeller to the resting position, i.e. position of non-interference with the fluid flow, and to bring the impeller out of the resting position and possibly rotating the impeller at the start of a turbine actuating step, in order to bring the radial members to the position of interference with the fluid flow and/or possibly also to bring the impeller to a sufficient number of revolutions to overcome the initial inertia thereof, therefore reaching the steady rotation status.

4. Generator according to claim 3, wherein the drive member consists of the alternator itself, which is in the form of an electric motor operating passively or operated by the turbine to which it is dynamically connected, whereas the power source can consist of an electric power accumulator charged and chargeable by the same electric power generated by the generator, the control unit of the motor being configured to supply it the actuating electric power so that to actively control the turbine or the impeller itself.

5. Generator according to claim 3 or 4 , wherein locking means to lock the impeller and which can be of the electric and/or mechanic type are provided, for example a break, and which are also controlled by the control unit of the alternator so that to synchronize with the actuation of the resting or energy generating step.

6. Generator according to one or more of claims 3 to 5 , wherein a sensor for detecting the position of the impeller of the turbine is provided to identify the resting position, or the position of non-interference with the fluid flow.

7. Generator according to one or more of the preceding claims, wherein the turbine, or impeller thereof, is coupled with the alternator or electric motor, by means of a rotary coupling of the magnetic type.

8. Acoustic reception/transmission unit to be particularly used in the water distribution network the unit comprising:

the control unit comprising a demodulation section of an electric reception signal provided by the electroacoustic reception transducer, the section extracting, from said reception signal, an encoding signal of the information transmitted by the modulation of the acoustic frequency carrier;

the control unit comprising a modulation section of an acoustic frequency carrier with an information encoding signal .

9. Acoustic reception/transmission unit according to claim 8, wherein the information, i.e. corresponding encoding signal of said information extracted from the reception signal, is provided to the modulation section for the generation of a transmission signal to the electroacoustic transmission transducer and of the acoustic transmission thereof to further reception/transmission units.

10. Acoustic reception/transmission unit according to claim 8 or 9, wherein the information encoded in the encoding signal provided to the modulation section consists of the measurement signals of at least one sensor selected among one or more of the following sensors: level sensors, flow sensors, loss sensors, temperature sensors, viscosity sensors, pressure sensors, flow rate sensors, and other sensors detecting the presence of one or more chemical substances in the fluid and combinations of said sensors, the control unit being provided with one or more doors for said one or more sensors .

11. Acoustic reception/transmission unit according to one or more of claims 8 to 10, wherein the information encoding signal extracted from the demodulation section is provided to a communication interface of the control unit, the communication interface transmitting said signal i.e. said information by means of one or more electromagnetic transmission protocols, both of the cable or wireless type, to a remote station, such as a data collection or management station.

12. Acoustic reception/transmission unit according to one or more of claims 8 to 11, wherein said acoustic reception/transmission unit can be supplied by means of a direct connection to an electric power network or can be energetically independent and self-supplied since it is provided with one or more electric power generators.

13. Acoustic reception/transmission unit according to claim 12, wherein at least one electric power generator is of the type according to one or more of claims 1 to 7.

14. Acoustic reception/transmission unit according to claim 13, wherein the acoustic reception/transmission unit consists of a pipe section in which a turbine is mounted, said pipe having an inlet branch connected to the inlet opening of the turbine and an outlet branch connected to the outlet opening of the turbine, an electroacoustic transmission and/or reception transducer being provided in each of the two inlet and outlet branches, preferably a reception transducer and a transmission transducer in both said inlet and outlet branches .

15. Acoustic reception/transmission unit according to one or more of claims 8 to 14 , wherein the information from the encoding signal modulated on the acoustic carrier, the invention provides that the modulation/demodulation sections are of the amplitude modulation type.

16. Acoustic reception/transmission unit according to claim 15, wherein the demodulation section and the modulation section operate at mutually synchronized time intervals relative to the transmission and reception.

17. Method for the acoustic transmission of data through a fluid, the method providing the modulation and demodulation of data on an acoustic carrier through amplitude modulation.

18. Method according to claim 17, wherein the step of synchronizing to the GPS coordinated universal time of the receiver and transmitter is provided.

19. Method according to claim 17 or 18, wherein the synchronization provides the definition of a time transmission window of the transmission signals and a sampling window of the reception signals, the windows being synchronized to one another according to the GPS coordinated universal time, the transmission signals being encoded in the form of packets with a code based on a differential time synchronization.

20. Method according to one or more of preceding claims 17 to 19, wherein the sampling window is subdivided in time intervals of one bit that can assume the 0 or 1 logic values corresponding to the signal present or signal absent status, the sampling signal being frequency filtered with a filter centered at the same frequency of the transmission carrier and the signal being subjected to the extraction of the envelope of the signal frequency modulated and subsequently sampled.

21. Method according to one or more of preceding claims 17 to 20, wherein the sampling occurs in a reception sampling range, said sampling range being greater than the transmission time plus the propagation time of the signal in the fluid, the so-called time of flight, and any shift between the clock of the receiver and the clock of the transmitter .

22. Method according to one or more of preceding claims 17 to 21, wherein the transmission signal is encoded so that to comprise, at a prefixed transmission range, a header followed by a pause and subsequently by the information, followed by the information negation and header negation, the content of the reception signal being extracted by demodulation and subjected to a detecting and validating step of the data frame, comprising the convolution of the entire signal with a function corresponding to the header known for the determination of the maximum and minimum values of the bits from which to determine the logic values 0 and 1 corresponding to the signal present or signal absent status.

23. Method according to one or more of preceding claims 17 to 22, wherein the validation of the data is further carried out by checking the information and header contents by comparing them to their negation.

24. Water supply network comprising at least one pipe connecting the two terminal nodes to, for example, a pumping station downstream of a water collection and distribution tank, the terminal nodes comprising, respectively, at least one transmission unit by means of an acoustic data carrier of at least one sensor associated with said first node and one reception unit of the acoustic transmission signal of said data to said second node, said units being obtained according to one or more of claims 8 to 16 and operating according to one or more of claims 17 to 23.

25. Water supply network according to claim 24, characterized by comprising several nodes comprising operative units with functions relative to the distribution of the fluid and in which, at one or more of said operative units, a reception/transmission unit according to one or more of claims 8 to 16 is provided, each of which acts as a repeater and communicates at least with one or more of the reception/transmission units directly connected to it by means of the fluid inside of a pipe section connecting said reception/transmission unit to a further reception/transmission unit.