DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
(See section 10 and rule 13)

A SYSTEM FOR ACOUSTIC POSITIONING IN UNDERGROUND MINES UTILIZING VISIBLE LIGHT-BASED SYNCHRONIZATION, AND METHOD THEREOF

TECHNOLOGY INNOVATION IN EXPLORATION & MINING FOUNDATION
a company incorporated in India, having address at
3rd Floor, i2h Tower (Institute Innovation Hub), IIT(ISM) Dhanbad, Jharkhand - 826004

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to a system for acoustic positioning in underground mines utilizing visible light-based synchronization, and method thereof.

BACKGROUND OF THE INVENTION
Positioning systems and methods have been widely used for determining the position of an underground object. For instance, the primary requirement for the safety of miners is a positioning system since underground mining is such a tough and dangerous environment because of poor visibility, release of toxic fumes, inadequate ventilation, and in-mine vehicular accidents. In addition to that, collapses may lead to casualties.

There are numerous technologies employed in positioning systems. However, Global Navigation Satellite Systems (GNSS) do not function accurately due to their insufficient reach underground. RF-based locating systems may offer high coverage in open fields, but because of the uneven structure of mines, RF signals may encounter problems underground, such as multipath propagation, signal strength loss, scattering, etc. Non-RF based positioning systems like Acoustic signals, Visible light and Magnetic Induction have their own advantages as well as some drawbacks when compared to RF-based positioning systems in underground mining areas.

As signal measuring technologies, Time of Arrival (ToA), Time Difference of Arrival (TDoA), and Received Signal Strength are utilized extensively by the aforementioned positioning system approaches. While these approaches involve the transmission and receipt of signals for position estimation, synchronization is crucial throughout the transfer of data towards the receiver. In addition to synchronization, time stamping is required, particularly for ToA and TDoA where time delay measurement is needed. Typically, cable synchronization or RF signals are used in conjunction with other location estimation technologies for synchronization. The wired synchronization increases the system's bulkiness. RF signals are utilized as synchronization signals, although they may experience multipath propagation, signal scattering due to the presence of dust particles, and uneven mine construction. If the synchronization signal cannot reach its destination on time, data may be lost or the user may misinterpret the received data, resulting in erroneous location estimation.

Therefore, the object of the present invention is to solve one or more synchronization issues.

SUMMARY OF THE INVENTION
This summary is provided to introduce concepts related to a system for acoustic positioning in underground mines utilizing visible light-based synchronization, and method thereof. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

A system for acoustic positioning in underground mines utilizing visible light-based synchronization, and method thereof is described. The system comprises a transmitting unit (110) for transmitting the visible light and acoustic signals, and a receiving unit (120) for receiving the visible light and acoustic signals. The transmitting unit (110) comprises a master unit (111) for the production and synchronization of acoustic and visible light signals, a light emitting diode (LED) unit (112) for transmitting visible light through at least one light emitting diode (LED) (1121), and an acoustic unit, wherein the acoustic unit comprises at least one frequency divider unit (1131), at least one multiplexer (MUX) and demultiplexer (DEMUX) unit (1132), at least one channel power amplifier (1133a, 1133b), and at least one speaker (1134a, 1134b, 1134c, 1134d) for transmitting acoustic signals.

The receiving unit (120) comprises a light detecting resistor (LDR) (121) for receiving visible light produced from the LED (1121) of transmitting unit (110), a microphone (122) for receiving acoustic signals produced from at least one speaker (1134a, 1134b, 1134c, 1134d) of the transmitting unit (110), an analog-to-digital converter (ADC) (123) connected to the LDR (121) and the microphone (122), and a digital signal processing (DSP) unit (124) connected to the ADC (123).

The method comprising the steps of:
a. generating a signal, by a master unit (111);
b. transmitting, by a transmitting unit (110), a visible light through a light emitting diode (LED) unit (112) and an acoustic signal through an acoustic unit;
c. receiving the visible light, by a light detecting resistor (LDR) (121) of a receiving unit (120), wherein the voltage of the light detecting resistor (LDR) (121) decreases on receipt of visible light signal thereby precisely syncing with the input frequency signal ensuring that the transmitter and receiver ends are synchronized;
d. receiving, by the microphone (122), the acoustic signals produced from at least one speaker (1134a, 1134b, 1134c, 1134d) of the transmitting unit (110); and
e. processing the signal to determine the distance and/or position.

BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, example of which may be illustrated in the accompanying figure(s). These figure(s) are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments. The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of apparatus, systems, and methods that are consistent with the subject matter as claimed herein, wherein:
Figure 1 shows a block diagram of synchronization system using Visible Light when used in combination with Acoustic System as Positioning System according to an embodiment of the present invention;
Figure 2 shows a graph indicating the receipt of visible light signal in synchronization with the acoustic signals when distance between receiver and reference speaker is 30 cm according to an embodiment of the present invention;
Figure 3 shows a graph indicating the receipt of visible light signal in synchronization with the acoustic signals when distance between receiver and reference speaker is 40 cm according to an embodiment of the present invention;
Figure 4 shows a graph indicating the receipt of visible light signal in synchronization with the acoustic signals when distance between receiver and reference speaker is 50 cm according to an embodiment of the present invention;
Figure 5 shows a graph indicating the receipt of visible light signal in synchronization with the acoustic signals when distance between receiver and reference speaker is 60 cm according to an embodiment of the present invention;
Figure 6 shows a graph indicating the receipt of visible light signal in synchronization with the acoustic signals when distance between receiver and reference speaker is 70 cm according to an embodiment of the present invention;
Figure 7 shows a graph indicating the receipt of visible light signal in synchronization with the acoustic signals when distance between receiver and reference speaker is 80 cm according to an embodiment of the present invention;
Figure 8 shows a comparison of the actual position of the receiver in the form of x and y coordinates with the derived position of the receiver from experiments according to an embodiment of the present invention; and
Figure 9 shows a visible light synchronization when Receiver’s coordinates are (150,50) according to an embodiment of the present invention.

The figures depict embodiments of the present subject matter for illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention disclose a continuous mineral concentrator. The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.

A system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization, and method thereof is described. In some embodiments, the system comprises a transmitting unit (110) for transmitting the visible light and acoustic signals, a receiving unit (120) for receiving the visible light and acoustic signals.

In some embodiments, the transmitting unit (110) comprises a master unit (111) for the production and synchronization of acoustic and visible light signals, a light emitting diode (LED) unit (112) for transmitting visible light through at least one light emitting diode (LED) (1121), and an acoustic unit, wherein the acoustic unit comprises at least one frequency divider unit (1131), at least one multiplexer (MUX) and demultiplexer (DEMUX) unit (1132), at least one channel power amplifier (1133a, 1133b), and at least one speaker (1134a, 1134b, 1134c, 1134d) for transmitting acoustic signals.

In some embodiments, the receiving unit (120) comprises a light detecting resistor (LDR) (121) for receiving visible light produced from the LED (1121) of transmitting unit (110), a microphone (122) for receiving acoustic signals produced from at least one speaker (1134a, 1134b, 1134c, 1134d) of the transmitting unit (110), an analog-to-digital converter (ADC) (123) connected to the LDR (121) and the microphone (122), and a digital signal processing (DSP) unit (124) connected to the ADC (123).

In some embodiments, the frequency divider unit (1131) is configured to excite transmitters with a single excitation signal.

In some embodiments, the digital signal processing (DSP) unit (124) is configured to process the data of signals to determine the distance and/or position of the receiving unit (120) in relation to the transmitting unit (110).

In some embodiments, the acoustic unit comprises three speakers (1134a, 1134b, 1134c) or four speakers (1134a, 1134b, 1134c, 1134d), and wherein the speakers are placed at different predefined locations from each other. At least three speakers are used for determining distance and/or position in two-dimension (2D), and at least four speakers are used for determining distance and/or position in three-dimension (3D).

In some embodiments, the light detecting resistor (LDR) (121) has voltage when there is no visible light signal. The light detecting resistor (LDR) (121) voltage decreases on receipt of visible light signal thereby precisely syncing with the input frequency signal ensuring that the transmitter and receiver ends are synchronized.

In some embodiments, the transmitting unit (110) and the receiving unit (120) can be respectively coupled with another receiving unit and the transmitting unit for acoustic positioning at both the ends thereby enabling full-duplex communication.

In some embodiments, the digital signal processing (DSP) unit (124) comprises a communication unit for transmitting the data to the transmitting unit (110), wherein the communication unit is any known communication device for transmitting the data.

In some embodiments, the master unit (111) is configured to receive the data from the digital signal processing (DSP) unit (124) to determine the distance and/or position of the transmitting unit (110) in relation to the receiving unit (120).

An example of placing speakers and determining the distance and/or position is described. Each speaker is located at a known distance. One is placed at origin at (0,0) coordinates. The second speaker is placed in some variation of X-coordinate as compared to origin. Likewise, the third speaker is placed which has a variation of Y-coordinate as compared to origin. In case of 3D positioning, the fourth speaker will have some variation in Z-coordinate as compared to origin. To determine 3D position, a trilateration method is used. An unknown position (x,y,z) is determined using distances from three known reference points (xi,yi,zi). The distance between unknown locations from each known location is calculated by using the euclidean distance formula.

Whenever the speakers are transmitting acoustic signals to detect the position of the miner, a synchronization signal from the LED is also transmitted to the receiver in order to inform the receiver of the transmission's time stamp. In other words, following computer processing, the user will be able to determine when the speaker began delivering acoustic signals based on the LED's synchronization signal. As a result, the information transmitted by the transmitter will not be lost on the receiving end.

In order to estimate the Time-of-Arrival of the signal from transmitter to receiver, auto-correlation operation is performed between the transmitted and received signals at the receiver side. Transmitted signal is known and is already stored in the DSP of the receiver. The received signal’s timestamp is important to perform the auto-correlation. Therefore, LDR will trigger the time-stamp to accurately perform the auto-correlation. The user gets distance and/or position from auto-correlation and the position is estimated based on the distance.

In underground mining, acoustic positioning systems and methods are adopted due to their inexpensiveness and effortlessness. It relies on the time-of-flight method for position estimation. In addition, the transmitters and receivers of an acoustic based positioning system are loudspeakers and microphones, respectively. Multiple transmitters are typically affixed on the mine structure, while the miner carries a receiver. Therefore, position estimation can be performed with a lighter load (only the receiver) carried by the miner. Trilateration is a method used to determine a position when the locations of at least three nodes are known. The distance between the receiver and each transmitter is computed based on the time of arrival. This allows the receiver’s location to be determined. Using these known nodes, it is possible to obtain a 2D as well as 3D location. The distance di between ith transmitter and a receiver can be calculated using the following equation:

where, xi, yi and zi are the coordinates of ith transmitters (speakers) and x, y and z are the unknown coordinates of the receiver (microphone). The coordinates for a reference node are chosen from among the three transmitters.

In some embodiments, the acoustic positioning system requires a minimum of three transmitters and one receiver. These spatially separated transmitters and receivers are connected through a synchronization link. Thus, both data loss and misinterpretation of received data can be avoided. Additionally, synchronization provides time stamping that can be sent to various nodes during data reception. As a result, these time indications facilitate the comprehension of data, such as the time at which transmitters transmitted signals and the time at which cross correlation should commence in order to determine the location of the receiver. High propagation speed and the presence of multi-path effects also necessitate synchronization. In emergency situations, the exact location of a miner in underground mines must be accurately retrieved, and synchronization is crucial for this. Therefore, synchronization between transmitters and receivers is the most important factor for miner safety.

Using visible light, the present disclosure provides a system and method of synchronization between transmitter and receiver. Visible light has a number of advantages, including less electromagnetic interference, less multipath effect, and being more environmentally friendly and secure. Moreover, visible light-based systems employ Light Emitting Diode (LED) as the transmitter and Photodiode (PD) or Light Detecting Resistor (LDR) as the receiver. LED has several advantages, including its low cost, long lifespan, minimal operating voltage, and resistance to environmental hazards. LED not only aids with synchronization but also provides illumination for the miners. In some instances, it may also assist in detecting the location of the miner.

Moreover, this visible light based synchronization and acoustic signal-based positioning system and method, take into account the fact that the speed of light in the air 340 m/s is significantly greater than that of sound 3×108 m/s.

A method for acoustic positioning in underground mines utilizing visible light-based synchronization is described. The method comprising the steps of:
f. generating a signal, by a master unit (111);
g. transmitting, by a transmitting unit (110), a visible light through a light emitting diode (LED) unit (112) and an acoustic signal through an acoustic unit;
h. receiving the visible light, by a light detecting resistor (LDR) (121) of a receiving unit (120), wherein the voltage of the light detecting resistor (LDR) (121) decreases on receipt of visible light signal thereby precisely syncing with the input frequency signal ensuring that the transmitter and receiver ends are synchronized;
i. receiving, by the microphone (122), the acoustic signals produced from at least one speaker (1134a, 1134b, 1134c, 1134d) of the transmitting unit (110); and
j. processing the signal to determine the distance and/or position.

In some embodiments, the step of generating the signal by the master unit (111) comprises production and synchronization of acoustic and visible light signals.

In some embodiments, the step of generating the signal by a master unit (111) comprises the step of exciting transmitters with a single excitation signal by a frequency divider unit (1131).

In some embodiments, the step of processing the signal to determine the distance and/or position comprises:
a. converting, by an analog-to-digital converter (ADC) (123), the analog signal to digital signal; and
b. processing, by a digital signal processing (DSP) unit (124), to determine the distance and/or position.
The present invention in an embodiment as shown in Figure 1 discloses a system of synchronization wherein acoustic signals are used to detect the position of a miner, and visible light is used as a synchronization signal, to facilitate comprehension.
To compute the distance between the transmitter and receiver, a positioning system based on acoustic signals uses the time-of-flight approach. Here, the speakers function as the transmitter and the microphone functions as the receiver of acoustic signals. Three speakers are employed in the experimental setup to detect the 2-D position of a miner. However, four speakers can be employed for position estimation in three dimensions. In the case of visible light, Light Emitting Diode (LED) is used as a transmitter alongside a speaker, whereas Light Detecting Resistor (LDR) is used as receiver along with a microphone.

As shown in Figure 1, on the transmitter side, a master unit is employed for the production and coordination of acoustic and visible light signals. Due to the frequency divider network or frequency divider unit, it is possible to excite all transmitters with a single excitation signal. The acoustic and visual light signals are synced such that whenever one of the four speakers turns on, the LED will also illuminate. It is well known, the speed of sound in air is slower than the speed of light. Utilizing this phenomenon, on the receiving side, visible light signals will arrive sooner than audio signals. LDR will receive light signals and Microphone will receive sound signals on the receiver side.
In the actual world, whenever the speakers are transmitting acoustic signals to detect the position of the miner, a synchronization signal from the LED is also transmitted to the receiver in order to inform the receiver of the transmission's time stamp. In other words, following computer processing, the user will be able to determine when the speaker began delivering acoustic signals based on the LED's synchronization signal. As a result, the information transmitted by the transmitter will not be lost on the receiving end.
The visible light signal that is synchronized with one of the speakers is depicted from Figures 2 to 7. As demonstrated in the graphs, LDR has some voltage when there is no visible light signal present. According to the LDR's operating principle, as soon as visible light strikes an LDR, the voltage across the LDR will decrease. It is synced precisely with the input frequency signal. And therefore, it indicates that the transmitter and receiver ends are synchronized.
Figure 8 depicts the actual or physical coordinates of the receiver in two dimensions. The experimental results are compared to the actual receiver coordinates in order to verify the positioning system's functionality. As shown in Figure 8 experimental results are in close proximity to the actual receiver coordinates. Changes in the environment and the transmitter's alignment cause some error, which can be compensated for by the calibration.
In order to collect the data, transmitters (speakers) are already present at known locations. Additionally, the microphone has been placed at various places. For the experimental verification, the user already knows the coordinate of the microphone but it is verified against the signals received by the microphone, transmitted by speakers. Both the results are compared in the graph of 2D positioning where actual location and derived location is plotted in terms of 2D coordinates.
Figure 9 explains the synchronization process. Square wave signals are the transmitter signals from four speakers. The signals received by the microphone on the receiver side are also shown in the graph. From the zoomed-in picture in the graph, it can be seen that as soon as the transmitter sends the acoustic signal, the LED has been illuminated and the decrease in voltage across LDR at the same instance shows that LDR has received visible light signals from LED. This shows that the synchronization method is working properly without any loss of data on the receiving side.

EXPERIMENTAL SETUP, RESULT, AND CONCLUSION
1. METHODOLOGY
In an acoustic-based positioning system, a frequency dividing network is used to transmit acoustic signals sequentially through acoustic transmitters, for example, speakers (1134a, 1134b, 1134c, 1134d), as shown in Figure 1 at the transmitter end. For visible light-based synchronization, an LED and its driver circuit are present.

However, an LED is synchronized with an acoustic transmitter through a timer circuit so that it illuminates whenever the transmitter transmits a sound signal. In addition to this, there is a master unit for the generation and co-ordination of audible and visible light signals.

At the extremity of the receiver is a microphone for receiving acoustic signals and an LDR for receiving visible light signals. ADC (analog-to-digital converter) collects the data with a time stamp, and software is used for subsequent processing like cross-correlation and calculation of location on the basis of the received data.

2. EXPERIMENTAL SETUP
On the table, a configuration of 2 × 0.8 m2 was prepared for the 2D acoustic-based positioning system. In the experiment, three speakers (SP1, SP2, and SP3) were used as acoustic transmitters. In addition, a frequency divider network, LED, and its driver circuit were present at the transmitter end. The test was conducted in a confined atmosphere at room temperature. Standard values for speed of light and sound were assumed as per environmental conditions. The details of hardware components are shown in Table 1. At the receiver end, a microphone and LDR were present in order to receive the audible and visible light signals. ADC collected the data, which was then processed by MATLAB software. The resolution of ADC is 14 bits.

3. TEST FOR POSITIONING AND SYNCHRONIZATION
The master unit sends a chirp signal synchronized with a square-wave signal to the frequency divider network. Time division multiplexing is used to sequentially transmit signals to acoustic transmitters. In addition to that, the LED is synchronized to turn on whenever one of the three acoustic transmitters transmit an acoustic signal. In this experiment, synchronization is performed with the third transmitter. On the receiver side, this chirp signal is received by the microphone and the LDR receives the visible light signal. The time of arrival is determined by performing cross-correlation between digitized transmitted and received signals. After cross-correlation between these signals, positioning and synchronization related data can be extracted.

4. EXPERIMENTAL RESULTS
In order to have results for 2D positioning, the microphone was placed at different locations on the table and the distance between acoustic transmitters and receiver was estimated. Furthermore, synchronization was tested at various transmitter-to-receiver distances. As depicted in Figure 9, as soon as the third transmitter turns on, a sharp voltage decrease can be observed across the LDR. The on timing of the transmitter can be determined from the square pulses. There is no noticeable difference between the generated acoustic signal and the received visible light signal. This establishes the feasibility of using visible light as a synchronization signal in conjunction with an acoustic based 2D positioning system. From the received data with a timestamp, a base station located above the ground in case of underground mining, can be able to recognize the point at which cross-correlation should start in order to determine the position. Additionally, to round out the entire system, Figure 8 represents the acoustic-based positioning results. In the x-direction, approximately 1 m of the range was covered, and in the y-direction, approximately 60 cm of the range was covered. As shown in Figure 8, the system was able to locate the microphone with a ± 3cm margin of error.

5. CONCLUSION
This system and method utilizes visible light as a synchronization method in association with an acoustic-based 2D positioning system. When determining the location of a miner in an underground mining environment, synchronization signals play a crucial role. The present disclosure provides a precise system and/or method for synchronization, particularly for underground mining. The system and method can be beneficial support for the aboveground base station that is used to determine the location of miners in underground mines. Here, the positioning system can locate the microphone with a ± 3cm error. The experimental results indicate that there is no significant delay between transmitted acoustic and received visible light signals so, the visible light signal can be used as a synchronization signal without any data loss, which is a crucial factor for underground mining in emergency circumstances. The proposed system necessitates knowledge of the speed of acoustic and visible light signals in the specific environment.

INDUSTRIAL APPLICABILITY
Underground and indoor positioning systems are the main commercial application of this synchronization method. It is compatible with both RF and non-RF based systems. This invention is more cost-effective than existing synchronization techniques. Currently, both wired synchronization and RFID based systems are being used for the same purpose. However, LED is less expensive and has a longer lifespan than its competitors. In a realistic context, it is simpler to implement an LED into the system than RF signals and wires.

The title and description of this patent are provided for indicative purposes only, to illustrate its application within the context of the mining industry. However, the invention is not limited to this industry alone. It may have broader applications and utility across other industries, fields, or scenarios, as would be apparent to those skilled in the art. The mention of a specific industry is not intended to restrict the scope of the invention, and potential uses in alternative contexts are expressly contemplated.

It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.

We claim:
1. A system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization comprises:
1.1. a transmitting unit (110) for transmitting the visible light and acoustic signals comprises:
1.1.1. a master unit (111) for the production and synchronization of acoustic and visible light signals;
1.1.2. a light emitting diode (LED) unit (112) for transmitting visible light through at least one light emitting diode (LED) (1121); and
1.1.3. an acoustic unit, wherein the acoustic unit comprises:
1.1.3.1. at least one frequency divider unit (1131);
1.1.3.2. at least one multiplexer (MUX) and demultiplexer (DEMUX) unit (1132);
1.1.3.3. at least one channel power amplifier (1133a, 1133b); and
1.1.3.4. at least one speaker (1134a, 1134b, 1134c, 1134d) for transmitting acoustic signals;
1.2. a receiving unit (120) for receiving the visible light and acoustic signals comprises:
1.2.1. a light detecting resistor (LDR) (121) for receiving visible light produced from the LED (1121) of transmitting unit (110);
1.2.2. a microphone (122) for receiving acoustic signals produced from at least one speaker (1134a, 1134b, 1134c, 1134d) of the transmitting unit (110);
1.2.3. an analog-to-digital converter (ADC) (123) connected to the LDR (121) and the microphone (122); and
1.2.4. a digital signal processing (DSP) unit (124) connected to the ADC (123).

2. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the frequency divider unit (1131) is configured to excite transmitters with a single excitation signal.

3. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the digital signal processing (DSP) unit (124) is configured to process the data of signals to determine the distance and/or position of the receiving unit (120) in relation to the transmitting unit (110).

4. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the acoustic unit comprises three speakers (1134a, 1134b, 1134c) or four speakers (1134a, 1134b, 1134c, 1134d), and wherein the speakers are placed at different predefined locations from each other.

5. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein at least three speakers are used for determining distance and/or position in two-dimension (2D), and at least four speakers are used for determining distance and/or position in three-dimension (3D).

6. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the light detecting resistor (LDR) (121) has voltage when there is no visible light signal.
7. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the light detecting resistor (LDR) (121) voltage decreases on receipt of visible light signal thereby precisely syncing with the input frequency signal ensuring that the transmitter and receiver ends are synchronized.

8. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the transmitting unit (110) and the receiving unit (120) can be respectively coupled with another receiving unit and the transmitting unit for acoustic positioning at both the ends thereby enabling full-duplex communication.

9. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the digital signal processing (DSP) unit (124) comprises a communication unit for transmitting the data to the transmitting unit (110), wherein the communication unit is any known communication device for transmitting the data.

10. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the master unit (111) is configured to receive the data from the digital signal processing (DSP) unit (124) to determine the distance and/or position of the transmitting unit (110) in relation to the receiving unit (120).

11. A method for acoustic positioning in underground mines utilizing visible light-based synchronization comprising the steps of:
11.1. generating a signal, by a master unit (111);
11.2. transmitting, by a transmitting unit (110), a visible light through a light emitting diode (LED) unit (112) and an acoustic signal through an acoustic unit;
11.3. receiving the visible light, by a light detecting resistor (LDR) (121) of a receiving unit (120), wherein the voltage of the light detecting resistor (LDR) (121) decreases on receipt of visible light signal thereby precisely syncing with the input frequency signal ensuring that the transmitter and receiver ends are synchronized;
11.4. receiving, by the microphone (122), the acoustic signals produced from at least one speaker (1134a, 1134b, 1134c, 1134d) of the transmitting unit (110); and
11.5. processing the signal to determine the distance and/or position.

12. The method for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 11, wherein the step of generating the signal by the master unit (111) comprises production and synchronization of acoustic and visible light signals.

13. The method for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 11, wherein the step of generating the signal by a master unit (111) comprises the step of exciting transmitters with a single excitation signal by a frequency divider unit (1131).

14. The method for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 11, wherein the step of processing the signal to determine the distance and/or position comprises:
14.1. converting, by an analog-to-digital converter (ADC) (123), the analog signal to digital signal; and
14.2. processing, by a digital signal processing (DSP) unit (124), to determine the distance and/or position.

15. The method for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 11, wherein at least three speakers are used for determining distance and/or position in two-dimension (2D), and at least four speakers are used for determining distance and/or position in three-dimension (3D).

Dated this February 26, 2025.

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Nishidh Patel
Registered Patent Agent: IN/PA/2399
SINGHANIA & CO. LLP

ABSTRACT

A SYSTEM FOR ACOUSTIC POSITIONING IN UNDERGROUND MINES UTILIZING VISIBLE LIGHT-BASED SYNCHRONIZATION, AND METHOD THEREOF

A system for acoustic positioning in underground mines utilizing visible light-based synchronization, and method thereof is described. The system comprises a transmitting unit (110) for transmitting the visible light and acoustic signals, and a receiving unit (120) for receiving the visible light and acoustic signals. The receiving unit (120) comprises a light detecting resistor (LDR) (121) for receiving visible light produced from the LED (1121) of transmitting unit (110), a microphone (122) for receiving acoustic signals produced from at least one speaker (1134a, 1134b, 1134c, 1134d) of the transmitting unit (110), an analog-to-digital converter (ADC) (123) connected to the LDR (121) and the microphone (122), and a digital signal processing (DSP) unit (124) connected to the ADC (123).

Reference Figure: Figure 1

,CLAIMS:We claim:
1. A system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization comprises:
1.1. a transmitting unit (110) for transmitting the visible light and acoustic signals comprises:
1.1.1. a master unit (111) for the production and synchronization of acoustic and visible light signals;
1.1.2. a light emitting diode (LED) unit (112) for transmitting visible light through at least one light emitting diode (LED) (1121); and
1.1.3. an acoustic unit, wherein the acoustic unit comprises:
1.1.3.1. at least one frequency divider unit (1131);
1.1.3.2. at least one multiplexer (MUX) and demultiplexer (DEMUX) unit (1132);
1.1.3.3. at least one channel power amplifier (1133a, 1133b); and
1.1.3.4. at least one speaker (1134a, 1134b, 1134c, 1134d) for transmitting acoustic signals;
1.2. a receiving unit (120) for receiving the visible light and acoustic signals comprises:
1.2.1. a light detecting resistor (LDR) (121) for receiving visible light produced from the LED (1121) of transmitting unit (110);
1.2.2. a microphone (122) for receiving acoustic signals produced from at least one speaker (1134a, 1134b, 1134c, 1134d) of the transmitting unit (110);
1.2.3. an analog-to-digital converter (ADC) (123) connected to the LDR (121) and the microphone (122); and
1.2.4. a digital signal processing (DSP) unit (124) connected to the ADC (123).

2. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the frequency divider unit (1131) is configured to excite transmitters with a single excitation signal.

3. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the digital signal processing (DSP) unit (124) is configured to process the data of signals to determine the distance and/or position of the receiving unit (120) in relation to the transmitting unit (110).

4. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the acoustic unit comprises three speakers (1134a, 1134b, 1134c) or four speakers (1134a, 1134b, 1134c, 1134d), and wherein the speakers are placed at different predefined locations from each other.

5. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein at least three speakers are used for determining distance and/or position in two-dimension (2D), and at least four speakers are used for determining distance and/or position in three-dimension (3D).

6. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the light detecting resistor (LDR) (121) has voltage when there is no visible light signal.
7. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the light detecting resistor (LDR) (121) voltage decreases on receipt of visible light signal thereby precisely syncing with the input frequency signal ensuring that the transmitter and receiver ends are synchronized.

8. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the transmitting unit (110) and the receiving unit (120) can be respectively coupled with another receiving unit and the transmitting unit for acoustic positioning at both the ends thereby enabling full-duplex communication.

9. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the digital signal processing (DSP) unit (124) comprises a communication unit for transmitting the data to the transmitting unit (110), wherein the communication unit is any known communication device for transmitting the data.

10. The system (100) for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 1, wherein the master unit (111) is configured to receive the data from the digital signal processing (DSP) unit (124) to determine the distance and/or position of the transmitting unit (110) in relation to the receiving unit (120).

11. A method for acoustic positioning in underground mines utilizing visible light-based synchronization comprising the steps of:
11.1. generating a signal, by a master unit (111);
11.2. transmitting, by a transmitting unit (110), a visible light through a light emitting diode (LED) unit (112) and an acoustic signal through an acoustic unit;
11.3. receiving the visible light, by a light detecting resistor (LDR) (121) of a receiving unit (120), wherein the voltage of the light detecting resistor (LDR) (121) decreases on receipt of visible light signal thereby precisely syncing with the input frequency signal ensuring that the transmitter and receiver ends are synchronized;
11.4. receiving, by the microphone (122), the acoustic signals produced from at least one speaker (1134a, 1134b, 1134c, 1134d) of the transmitting unit (110); and
11.5. processing the signal to determine the distance and/or position.

12. The method for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 11, wherein the step of generating the signal by the master unit (111) comprises production and synchronization of acoustic and visible light signals.

13. The method for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 11, wherein the step of generating the signal by a master unit (111) comprises the step of exciting transmitters with a single excitation signal by a frequency divider unit (1131).

14. The method for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 11, wherein the step of processing the signal to determine the distance and/or position comprises:
14.1. converting, by an analog-to-digital converter (ADC) (123), the analog signal to digital signal; and
14.2. processing, by a digital signal processing (DSP) unit (124), to determine the distance and/or position.

15. The method for acoustic positioning in underground mines utilizing visible light-based synchronization as claimed in claim 11, wherein at least three speakers are used for determining distance and/or position in two-dimension (2D), and at least four speakers are used for determining distance and/or position in three-dimension (3D).