KR102327442B1 - Apparatus and method for optical wireless communication based on color m-ary frequency shift keying and grayscale image - Google Patents

Abstract

The present invention relates to an optical wireless communication method based on color M-ary frequency shift keying (M-FSK), which transmits data at high speed in visible light communications based on a camera, and grayscale images and an apparatus thereof. According to one embodiment of the present invention, the optical wireless communication method allows a process to perform at least a part of each step. The optical wireless communication method comprises the following steps: receiving a data stream; separating at least a part of the data stream into three channels and modulating each of the separated data streams in an M-FSK method to generate an FSK modulated signal, wherein a frequency mapped to each channel with respect to the same bit code is different; synthesizing a plurality of FSK modulation signals modulated by each of the three channels and generating a color modulation signal on the basis of a preset bit-color mapping table; and controlling a light source of the same optical channel on the basis of the color modulation signal to receive the color modulation signal.

Description

Optical wireless communication method and apparatus based on color M-FSK and grayscale image

The present disclosure relates to an apparatus and method for transmitting a signal through optical wireless communication based on color M-ary Frequency Shift Keying (M-FSK) and grayscale images.

The content to be described below is only provided for the purpose of providing background information related to the embodiment of the present invention, and the content to be described does not naturally constitute the prior art.

Recently, Visible Light Communication (VLC) technology, a wireless communication technology that adds communication functions to visible light wavelengths using infrastructure in which lighting such as incandescent bulbs and fluorescent lamps is replaced with semiconductor LED (Light Emitting Diode) lighting, is being actively researched.

In addition, an optical camera communication (OCC) technology for demodulating a visible light communication signal received using a camera mounted on a user device such as a general smart phone or a car camera is also being developed.

The camera mounted on the user device may photograph the light source using a global shutter method or a rolling shutter method.

Prior art 1 discloses a technology for communicating by a camera-based M-FSK method based on a rolling-shutter type camera, but the general M-FSK method uses only one frequency from one light source at the same time. Because it can be used, it is difficult to transmit high-speed data.

Prior Art 2 discloses a communication technology using a color shift keying (CSK) method, but the general CSK method has a high probability of error depending on the reception environment-dependent color recognition in the receiving device, and is a separate technology for recovering it. There is a need for this. In addition, the CSK signal receiving device based on the photo detector has a problem in that it is difficult to recognize the signal due to the influence of ambient light when the distance from the transmitting device is increased.

Prior Art 1: Korean Patent Publication No. 10-165184 (registration on August 22, 2016) Prior art 2: Korean Patent Publication No. 10-1728518 (registered on Apr. 13, 2017)

An embodiment of the present disclosure provides an apparatus and method capable of transmitting data at high speed in visible light communication based on a camera.

Another embodiment of the present disclosure provides an apparatus and method capable of robustly and high-speed data transmission based on M-FSK modulation and CSK modulation modulated through visible light communication technology.

Another embodiment of the present disclosure provides an apparatus and method capable of demodulating an optical signal based on M-FSK modulation and CSK modulation modulated through visible light communication technology with an easy configuration.

The object of the present invention is not limited to the above-mentioned tasks, and other objects and advantages of the present invention that are not mentioned may be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be appreciated that the objects and advantages of the present invention may be realized by means of the instrumentalities and combinations thereof indicated in the claims.

An optical signal transmission method according to an embodiment of the present disclosure is an optical signal transmission method in which a processor performs at least a portion of each step, and includes receiving a data stream, dividing at least a portion of the data stream into three channels, and separating A step of generating an FSK-modulated signal by modulating each of the data streams in an M-FSK (Mary-Frequency Shift Keying) method. For the same bit code, frequencies mapped to each channel are different, and a plurality of modulated data streams in three channels are each different. synthesizing the FSK modulated signal of , generating a color modulated signal based on a preset bit-color mapping table, and transmitting the color modulated signal by controlling a light source of the same optical channel based on the color modulated signal. can

An optical signal transmission apparatus according to an embodiment of the present disclosure includes a light source unit including a color LED, a modulator for modulating an input signal, and a control unit for controlling the light source to transmit a modulated transmission signal, and the modulator includes the received data At least a part of the stream is divided into three channels, and the separated data stream is modulated by the M-FSK (Mary-Frequency Shift Keying) method to generate an FSK modulated signal, and the frequency mapped for each channel with respect to the same bit code is By synthesizing a plurality of FSK modulated signals that are different and each modulated in three channels, generating a color modulated signal based on a preset bit-color mapping table, and controlling the light source of the same optical channel based on the color modulated signal. and may be configured to transmit a color modulated signal.

An optical signal receiving method according to an embodiment of the present disclosure is an optical signal receiving method in which a processor of a signal receiving apparatus including a camera performs at least a part of each step, and a sensor signal of a camera photographing a light source including a color LED generating a grayscale image frame based on Step of extracting a frequency by Fourier transforming the FSK-modulated signal and demodulating the FSK-modulated signal in an M-FSK (Mary-Frequency Shift Keying) method based on a preset bit-frequency mapping table and frequency to generate a data stream may include

An optical signal receiving apparatus according to an embodiment of the present disclosure is electrically connected to a camera generating an image by receiving an optical signal, at least one processor, and the processor, and at least one code executed by the processor is stored. a memory, wherein the memory, when executed through the processor, causes the processor to generate a grayscale image frame based on a sensor signal from a camera that has photographed the light source including the color LED, and an area in the grayscale image frame where the light source was captured. Generates an FSK modulated signal by extracting grayscale level information from the FSK modulated signal, Fourier transforms the FSK modulated signal to extract a frequency, and M-FSK (Mary-FSK) the FSK modulated signal based on a preset bit-frequency mapping table and the frequency. It is possible to store the code that causes the demodulation to generate a data stream in a frequency shift keying method.

A signal transmission apparatus and method according to an embodiment of the present disclosure may improve data transmission speed in visible light communication by modulating and transmitting the modulated M-FSK modulated signal back to a color signal.

The signal transmission apparatus and method according to an embodiment of the present disclosure modulates and transmits the modulated M-FSK modulated signal back to a color signal, thereby reducing the error occurrence probability in visible light communication.

A signal receiving apparatus and method according to an embodiment of the present disclosure can demodulate an optical signal based on M-FSK modulation and CSK modulation modulated through visible light communication technology with an easy configuration.

Effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description.

1 is a diagram schematically illustrating communication between a signal transmission apparatus and a signal reception apparatus according to an embodiment of the present disclosure.
2 is a block diagram illustrating a configuration of a signal transmission apparatus according to an embodiment of the present disclosure.
3 is a diagram for explaining an embodiment of a packet of a data stream according to an embodiment of the present disclosure.
4 is a diagram for explaining a frequency used for M-FSK modulation according to an embodiment of the present disclosure.
5 is a diagram for explaining a method of generating a color modulation signal based on an M-FSK modulation signal according to an embodiment of the present disclosure.
6 is a flowchart illustrating a signal transmission method according to an embodiment of the present disclosure.
7 is a block diagram illustrating a configuration of a signal receiving apparatus according to an embodiment of the present disclosure.
8 is a diagram for explaining a method of demodulating a received optical signal according to an embodiment of the present disclosure.
9 is a flowchart illustrating a signal reception method according to an embodiment of the present disclosure.

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but the same or similar components are assigned the same reference numerals regardless of reference numerals, and overlapping descriptions thereof will be omitted. The suffixes "module" and "part" for the components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have a meaning or role distinct from each other by themselves. In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in the present specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed herein is not limited by the accompanying drawings, and all changes included in the spirit and scope of the present invention , should be understood to include equivalents or substitutes.

Terms including an ordinal number, such as first, second, etc., may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

When a component is referred to as being “connected” or “connected” to another component, it is understood that the other component may be directly connected or connected to the other component, but other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that no other element is present in the middle.

Communication between a signal transmitting apparatus and a signal receiving apparatus according to an embodiment of the present disclosure will be described with reference to FIG. 1 .

Referring to FIG. 1 , the signal transmitting apparatus 100 receives data, modulates it based on M-FSK, and transmits a transmission signal modulated into a color signal as a visible light signal through the light source unit 130 including a color LED. can be configured to

The signal receiving device 200 receives the grayscale image information from the grayscale image generated based on the sensor signal of the camera that has photographed the light source unit 130 including the color LED through the camera 210 (rolling camera or global camera). Data can be generated by extracting the FSK-modulated signal (220), and by demodulating it based on the M-FSK after the M-FSK decoder 230 extracts a frequency from the FSK-modulated signal.

In order to modulate data by the M-FSK method, the signal transmission apparatus 100 may divide data into three channels and then modulate data for each channel by the M-FSK method.

The signal transmission apparatus 100 may generate a color modulated signal based on a signal obtained by synthesizing a plurality of FSK modulated signals modulated by each of the three channels. It will be described in detail below based on FIG. 5 .

The signal transmission apparatus 100 may transmit the color modulation signal as a visible light signal by controlling the light source unit 130 including the color LED to emit light according to the color modulation signal.

The signal receiving apparatus 200 may generate an image frame by photographing the light source of the signal transmitting apparatus 100 including the color LED.

The signal receiving apparatus 200 may determine the light source region from the image frame and extract grayscale level information from the image frame of the light source region.

The signal receiving apparatus 200 generates an FSK modulated signal based on the extracted grayscale level information, and Fourier transforms portions corresponding to a preamble and a payload of the FSK modulated signal to extract a frequency. . The signal receiving apparatus 200 may demodulate the FSK-modulated signal in an M-FSK method based on the extracted frequency and a preset bit-frequency mapping table and generate a data stream.

A configuration of a signal transmission apparatus according to an embodiment of the present disclosure will be described with reference to FIG. 2 .

Referring to FIG. 2 , the signal transmission apparatus 100 includes a color M-FSK encoder 110 , a serial-to-parallel (S2P) converter, a preamble inserter, a color M-FSK encoder 110, and a color modulator. ) and a control unit 120 for controlling the light source unit 130 that is a communication channel including a modulation unit 110 and an LED light source, and may include a clock generator for generating a clock signal. .

In an embodiment, the data stream may be a packet obtained by modulating a signal to be transmitted into a binary signal. The modulator may include a forward error correction (FEC) encoder, a preamble inserter, and a binary modulator that modulates input data into a binary signal.

In an embodiment, the color M-FSK encoder 110 may modulate a data stream in which a binary signal is formed in a packet form into a color code data signal. In the following description, it is assumed that the color M-FSK encoder 110 modulates a data stream that is a binary signal into a color code data signal.

In an embodiment, the color M-FSK encoder 110 may generate a binary data signal by line-coding a binary signal. Line coding may be a modulation in which input bit 0 is output as 00 and input bit 1 is output as 01.

The data stream may be a packet including a payload corresponding to data to be transmitted and a preamble corresponding to a header.

In an embodiment, the signal transmission apparatus 100 may include a sequence number in a packet, the sequence number may be assigned as a continuous number to consecutive data packets, and the sequence number may be a predetermined number ( bits) may be used repeatedly in order. For example, the sequence number may be 00 for the first packet, 01 for the second packet, and 00 for the third packet. The signal receiving apparatus 200 may determine whether packets are duplicated based on the sequence number.

A portion of the packet structure input to the color M-FSK encoder 110 according to an embodiment of the present disclosure will be described with reference to FIG. 3 . In another embodiment, the color M-FSK encoder 110 may modulate the input data by converting it into a part of a packet as shown in FIG. 3 .

Packets converted from input data may include a plurality of data packets i-1, i, and i+1.

Each of the plurality of data packets (i-1, i, i+1) includes a plurality of data subpackets (eg, data packet (i) includes data subpackets (i1, i2, i3), Each data subpacket may include a payload consisting of information bits corresponding to a portion of the input data.

In an embodiment, in order to prevent packet drop due to a variable frame rate of the receiving side camera, a plurality of data subpackets included in one data packet include the same payload composed of the same information bits. can do. That is, the same payload may be repeatedly transmitted to the signal receiving apparatus 200 .

The rolling camera of the signal receiving device 200 continuously photographs the blinking of the LED light source a plurality of times at different times, and stores each photographed signal in one column or row of the image sensor to generate an image frame. In this case, the frame rate of the camera may be variable according to device settings or the like, or may be lower than the data packet rate. Accordingly, in order to prevent packet reception from being dropped due to the frame rate limit of the rolling camera, the signal transmitting apparatus 100 may configure the data packet to include data subpackets including the same payload in duplicate. That is, the data subpackets i1 , i2 , and i3 may include the same payload.

In an embodiment, in order to detect packet omission in the signal reception device 200 or to distinguish duplicate packets, the signal transmission device 100 may assign a sequence number to each data packet or data subpacket. And, the sequence number may be assigned as a continuous number for consecutive data packets.

In an embodiment, each data subpacket i1 , i2 , and i3 may include the same payload as the sequence number of the data packet i and information bits allocated to the data packet i.

In one embodiment, the sequence number may be inserted at the front end of the packet, or in another embodiment, it may be inserted at both the front end and the rear end of the packet. When the sequence number is inserted at both the front and rear ends of the packet, the signal receiving apparatus 200 considers the sequence number before and after the preamble when finding one preamble in one captured image frame. A packet can be configured by backward decoding.

In an embodiment, the modulated packet or data subpacket may include a header part including meta information such as a size of the packet in the preamble.

In another embodiment, the preamble is a bit code indicating the start of a packet (Start Frame: SF) and may be a bit code known in advance to the signal transmission apparatus and the signal reception apparatus.

In another embodiment, the signal transmission apparatus 100 may include a Forward Error Correction (FEC) encoder and an Ab bit (asynchronous bits) inserter. The preamble may include Ab bits.

The color M-FSK encoder 110 of the signal transmission apparatus 100 may divide at least a portion of a serial-type packet or a packet into which a preamble is inserted into three channels, and then modulate each of them using the M-FSK method. .

For example, when the bit code of the payload of the packet is '00 01 10', the signal transmission apparatus 100 divides the bit code '00 01 10' of the payload into three channels for a predetermined number of bits, and each ' After dividing into 00', '01', and '10', each of the separated bit codes may be modulated using the M-FSK method.

In an embodiment, the preamble may be M-FSK-modulated for each channel or may be M-FSK-modulated for any one channel. In case of M-FSK modulation in one channel, the preamble is not input to each channel separately, but is color-modulated based on the pulse wave modulated the preamble in one channel, and only the bit code of the payload is separated and input to each channel can do.

A method of modulating a bit code input for each channel by the color M-FSK encoder 110 based on a preset bit frequency mapping table according to an embodiment of the present disclosure will be described with reference to FIG. 4 .

The color M-FSK encoder 110 may map the frequency of the bit code input for each channel based on a table as shown in Table 1 below.

In Table 1, two preambles are mapped to the same frequency in all three channels as an example, but in another embodiment, like other bit codes, the preamble may also be mapped to different frequencies in each channel. The following embodiments will be described on the assumption that both preambles are mapped to the same frequency in three channels.

The band of each frequency mapped to the bit code of the preamble and the payload may be as shown in FIG. 4 (a).

In an embodiment, the frequencies f0 and f5 mapped to the preamble may be a frequency of the lowest band or a frequency of the highest band in the bit-frequency mapping table. In addition, the bit code of the payload includes frequencies (f1, f2, f3) located at equal band intervals between the frequencies of the lowest and highest bands in the bit-frequency mapping table, that is, frequencies mapped to the preamble. , f4, hereinafter referred to as a fundamental frequency) or a frequency spaced apart from the fundamental frequencies f1, f2, f3, and f4 located at equal band intervals by a predetermined band distance. Although FIG. 4 shows four fundamental frequencies f1, f2, f3, and f4 located at equal band intervals among frequencies mapped to the bit code of the payload, the number of bit codes to be modulated and the number of frequencies mapped to the preamble A person skilled in the art can understand that the number of fundamental frequencies mapped to the bit code of the payload may be changed according to the band of the frequencies f0 and f5.

The frequency mapped to the bitcode of the payload is described in more detail.

As can be seen from <Table 1>, the bitcodes of the payload may be mapped to different frequencies when they are input to different channels even if they are the same bitcode. For example, bit code '10' maps to frequency 'F1' when input to the red channel, but to frequency 'F1 + Δf' when input to the green channel and frequency 'F1 - Δf' when input to the red channel. can be mapped. Here, the color for each channel may be changed according to an implementation example.

That is, the same bit code of the payload is mapped to the fundamental frequency in one channel as can be confirmed in the frequency band of FIG. can be mapped.

For this reason, even when the same bit code is repeated in the payload (as shown in FIG. 3, a case in which bit code '01 01 01' of the payload is separately input to three channels and the bit frequency is mapped can be taken as an example), Since the same bit codes input to each channel are mapped to frequencies of different frequency bands, it can be checked whether the same bit code is repeated when the signal receiving apparatus 200 demodulates them. In particular, when the signal receiving apparatus 200 demodulates in the M-FSK method based on the grayscale image, it cannot be demodulated after dividing into color channels according to color information. Accordingly, when the signal transmitting apparatus 100 maps the same bit code to the same frequency for each channel, the signal receiving apparatus 200 may not check whether the same bit code is repeated or some packets are missing. Therefore, when the same bit code of the payload is mapped to a frequency of a different band for each channel, even when the signal receiving apparatus 200 demodulates the M-FSK method based on the grayscale image, it is possible to safely demodulate the packet. There are advantages.

In an embodiment, the signal transmission apparatus 100 may first transmit the preamble-converted optical signal when transmitting the data-modulated color optical signal.

Accordingly, the signal receiving apparatus 200 may determine the band of the fundamental frequency corresponding to the bit code of each payload by demodulating the preamble from the received optical signal and extracting the corresponding frequency. For example, the signal receiving apparatus 200 divides the bands of frequencies (f0, f5) extracted by demodulating the preamble equally by a known number to obtain a band of a fundamental frequency corresponding to the bit code of each payload. can decide

That is, the signal transmission apparatus 100 transmits the color modulated signal in which the FSK modulated signal to which the frequency of the lowest band and the frequency of the highest band are mapped, and then transmits the color modulated signal modulated based on the payload. , even if the signal transmission device 100 changes the frequency band of the bit frequency mapping table and modulates it in the M-FSK method, the signal reception device 200 may determine each frequency band of the bit frequency mapping table without separately transmitting the table .

After determining the basic frequency band, the signal receiving apparatus 200 may determine frequencies of a band separated by a preset frequency band Δf from each basic frequency as frequencies of other channels.

Referring to FIG. 5 , the color M-FSK encoder 110 according to an embodiment of the present disclosure modulates the FSK modulated signals 510 , 520 , and 530 input for each channel based on a preset bit color mapping table. explain

5 illustrates the color modulator for the case where the M-FSK encoder M-FSK modulates the preamble for each channel. Color modulation is possible based on the spar. In this case, color modulation may be performed based on a preset bit color mapping table, assuming that there are the same three pulse waves modulated with the preamble.

5 shows, as an example, that the same bit codes of the payload are respectively input to each channel. That is, as shown in FIG. 3 , a case in which bit code '01 01 01' of the payload is separately input to each of three channels and the bit frequency is mapped is shown as an example.

The color modulator may generate the color modulated signal based on the level signal at the same position on the time axis in the FSK modulated signals 510, 520, and 530 modulated in each channel, and the FSK modulated signals 510, 520, and 530 may be in the form of a pulse wave.

For example, the color modulation signal 541 is based on a bit color mapping table as shown in Table 2 below, which is a level signal of '000' at the same time position of the FSK modulation signals 510, 520, and 530 for each channel. It may be a color modulation signal (which may be in the form of a control signal such as a voltage signal for controlling the color of a color LED) corresponding to the 'black' color generated by

Similarly, the color modulated signal 543 corresponds to the 'white' color generated based on the bit color mapping table in which '111', which is the level signal at the same time position of the FSK modulated signals 510, 520, and 530 for each channel, corresponds to a 'white' color. The color modulated signal, and the color modulated signal 545 is a 'white' color generated based on a bit color mapping table of '000', which is a level signal at the same time position of the FSK modulated signals 510, 520, and 530 for each channel. is a color modulation signal corresponding to , and the color modulation signal 547 is a level signal of the same time position of the FSK modulation signals 510, 520, and 530 for each channel, '001' (a red channel in the middle) is a bit color mapping It is a color modulated signal corresponding to the 'blue' color generated based on the table, and the color modulated signal 549 is a level signal '101' at the same time position of the FSK modulated signals 510, 520, and 530 for each channel. It may be a color modulation signal corresponding to a 'magenta (magenta)' color generated based on the bit color mapping table.

That is, the signal transmission apparatus 100 converts the level signals at the same position of each channel to bits according to the signal size of the FSK modulated signals 510, 520, and 530, and then converts the converted bits into a bit code concatenated (concatenate). A color modulation signal corresponding to the mapped color may be generated based on the bit color mapping table.

The color of the bit color mapping table may be a table in which the bits of each level signal are regarded as red, green, and blue, that is, each channel generating the FSK modulation signals 510, 520, and 530 is regarded as a three primary color channel. can

The control unit of the signal transmission apparatus 100 may transmit the color modulation signal as a visible light signal by controlling the emission color of the color LED of the light source unit 130 based on the generated color modulation signal.

When transmitting the color modulation signal, the signal transmission apparatus 100 may control the color LEDs so that all color LEDs included in the light source unit 130 emit light with only one color at the same time according to the color modulation signal.

A signal transmission method of a signal transmission apparatus according to an embodiment of the present disclosure will be described with reference to FIG. 6 .

The signal transmission apparatus may receive a packet in the form of a binary signal or receive a transmission signal and convert it into a packet in the form of a binary signal (S110).

The signal transmission apparatus may divide at least a portion of a packet by a predetermined number of bits, input it to a plurality of channels, and generate an FSK-modulated signal based on a preset bit frequency mapping table with bit codes input for each channel (S120). . In this case, the frequency mapped to the bit code for each channel may be as shown in <Table 1> described above.

The signal transmission apparatus may generate a color modulation signal corresponding to a color by mapping bit codes connecting level signals of the FSK modulation signal in the form of a pulse wave generated for each channel based on a preset bit color mapping table (S130). ).

The color modulation signal may be an electrical signal or command for controlling the color LED to emit light in a desired color, and the signal transmission device may transmit a visible light signal by controlling the color LED according to the generated color modulation signal (S140). ).

A configuration of the signal receiving apparatus 200 according to an embodiment of the present disclosure will be described with reference to FIG. 7 .

The signal receiving device 200 includes a rolling camera 210 that generates an image frame based on a signal obtained from an image sensor in a rolling-shutter method for receiving an optical signal, and a region in which a color LED is photographed in the image frame. After determining the grayscale level (grayscale level) information based on the image of the region to extract the grayscale information extractor 220 to generate an FSK modulated signal, the preamble detector to separate the preamble from the grayscale level information and determine the frequency of the preamble 240 and a color M-FSK decoder 230 for generating a data stream by demodulating the FSK modulated signal in an M-FSK (M-ary Frequency Shift Keying) method based on the frequency and bit-frequency mapping table of the preamble. can do.

A signal receiving method of the signal receiving apparatus 200 according to an embodiment of the present disclosure will be described with reference to FIGS. 8 and 9 .

The rolling camera continuously shoots the blinking of the LED light source a plurality of times at different times, and stores each captured signal in one column or row of the image sensor to generate an image frame (S210). The rolling camera sequentially exposes each row or column of the image sensor, so that a signal value corresponding to the color of the LED light source may be obtained according to the blinking of the LED light source in one column or row of the image sensor of the rolling camera. The rolling camera may be a color camera or a monochrome camera that produces a grayscale image.

The signal receiving apparatus 200 may generate a grayscale image frame based on a signal of a sensor photographing the color LED (S210). In the case of a color camera, a grayscale image may be generated from a color image based on information of each color channel (a variety of conventional methods for generating a grayscale image from a color image may be used), and in the case of a monochrome camera, a grayscale image may be directly generated. Signals configurable may be output from the camera sensor.

A rolling camera continuously shoots the blinking of an LED light source multiple times at different times, and stores each captured signal in one column or row of an image sensor to create an image frame. The rolling camera sequentially exposes each row or column of the image sensor, thereby obtaining a signal value corresponding to the color or brightness of the LED light source according to the blinking of the LED light source in one column or row of the image sensor of the rolling camera. A rolling camera may generate a plurality of image frames. In the description below, it is assumed that the rolling camera sequentially exposes each row of the image sensor.

The signal receiving apparatus 200 may extract grayscale level information 810 from the area in which the color LED is photographed. The grayscale level information may be grayscale intensity values extracted from each row or column of the area in which the color LED is photographed. have. The signal receiving apparatus 200 may generate grayscale level information as an FSK-modulated signal (S220).

The signal receiving apparatus 200 may determine a band of frequencies corresponding to the preamble by separating a signal corresponding to the preamble from the grayscale level information or the grayscale image frame, converting it to a frequency domain, and extracting frequencies.

The signal receiving apparatus 200 may determine a band of basic frequencies obtained by dividing two frequency bands of preambles in which a band of frequencies corresponding to each bit code used for demodulation of the payload is equally divided by a preset number. .

The signal receiving apparatus 200 may extract the frequency after transforming the FSK modulated signal 810 into a frequency domain based on a method such as Fourier Fast Transform (FFT) (S230).

The signal receiving apparatus 200 demodulates the FSK-modulated signal 810 based on the preset bit-frequency mapping table and the frequency extracted from the M-FSK (M-ary Frequency Shift Keying) method, and uses this as the payload of the packet. You can configure it to create a data stream. The data stream may be the packet described above.

The color M-FSK decoder 230 may determine the corresponding bit code by demodulating the FSK modulated signal 810 using the M-FSK method using the table of Table 1 described above. As described above, frequencies in different frequency bands (that is, the fundamental frequency and bands separated by a preset band Δf from the fundamental frequency) may be mapped to the same bit code.

Therefore, when demodulating a color M-FSK signal based on a grayscale image, there is an effect that the color M-FSK signal can be demodulated at a lower cost and easily by using a monochrome camera and one frequency conversion module.

The present disclosure described above can be implemented as computer-readable code on a medium in which a program is recorded. The computer-readable medium includes all types of recording devices in which data readable by a computer system is stored. Examples of computer-readable media include Hard Disk Drive (HDD), Solid State Disk (SSD), Silicon Disk Drive (SDD), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. there is this In addition, the computer may include a processor of each device.

Meanwhile, the program may be specially designed and configured for the present disclosure, or may be known and available to those skilled in the art of computer software. Examples of the program may include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like.

In the specification of the present disclosure (especially in the claims), the use of the term "above" and similar referential terms may be used in both the singular and the plural. In addition, when a range is described in the present disclosure, each individual value constituting the range is described in the detailed description of the invention as including the invention to which individual values belonging to the range are applied (unless there is a description to the contrary). same as

Steps constituting the method according to the present disclosure may be performed in an appropriate order unless there is an explicit order or description to the contrary. The present disclosure is not necessarily limited to the order of description of the above steps. The use of all examples or exemplary terminology (eg, etc.) in the present disclosure is merely for the purpose of describing the present disclosure in detail, and the scope of the present disclosure is limited by the examples or exemplary terms unless limited by the claims. it's not going to be In addition, those skilled in the art will appreciate that various modifications, combinations, and changes may be made according to design conditions and factors within the scope of the appended claims or their equivalents.

Therefore, the spirit of the present disclosure should not be limited to the above-described embodiments, and the scope of the spirit of the present disclosure as well as the claims to be described later are equivalent to or equivalently changed therefrom. will be said to belong to

100: signal transmission device
200: signal receiving device

Claims (20)

An optical signal transmission method in which a processor performs at least a portion of each step, the method comprising:
receiving a data stream;
generating an FSK modulated signal by dividing at least a portion of the data stream into three channels and modulating each of the separated data streams using a Mary-Frequency Shift Keying (M-FSK) method, wherein the channel for the same bit code The frequencies mapped to each are different;
synthesizing a plurality of FSK modulated signals modulated on the three channels, respectively, and generating a color modulated signal based on a preset bit-color mapping table; and
Transmitting the color modulation signal by controlling a light source of the same optical channel based on the color modulation signal,
The generating of the color modulation signal comprises:
Further comprising the step of generating the color modulated signal based on the level signal at the same position on the time axis in the plurality of the FSK modulated signal in the form of a pulse wave,
Optical signal transmission method.
According to claim 1,
After converting the level signal of the plurality of FSK modulated signals into bits, the method further comprising the step of concatenating the converted bits to generate the color modulated signal,
Optical signal transmission method.
An optical signal transmission method in which a processor performs at least a portion of each step, the method comprising:
receiving a data stream;
generating an FSK modulated signal by dividing at least a portion of the data stream into three channels and modulating each of the separated data streams using a Mary-Frequency Shift Keying (M-FSK) method, wherein the channel for the same bit code The frequencies mapped to each are different;
synthesizing a plurality of FSK modulated signals modulated on the three channels, respectively, and generating a color modulated signal based on a preset bit-color mapping table; and
Transmitting the color modulation signal by controlling a light source of the same optical channel based on the color modulation signal,
The generating of the FSK modulated signal comprises:
The data stream separated based on a preset bit-frequency mapping table is modulated, and a preamble of the data stream is mapped to a frequency of a lowest band or a frequency of a highest band in the bit-frequency mapping table. further comprising generating an FSK modulated signal;
Optical signal transmission method.
4. The method of claim 3,
In the bit-frequency mapping table, the payload of the data stream maps frequencies located at equal band intervals between a frequency of the lowest band and a frequency of the highest band to a frequency of one channel to obtain the FSK modulated signal. further comprising the step of generating
Optical signal transmission method.
4. The method of claim 3,
Transmitting the color modulation signal comprises:
In the bit-frequency mapping table, after transmitting a color modulated signal in which an FSK modulated signal to which a frequency of the lowest band and a frequency of the highest band is mapped is transmitted, the color modulated based on the payload of the data stream Further comprising the step of transmitting a modulated signal,
Optical signal transmission method.
An optical signal transmission method in which a processor performs at least a portion of each step, the method comprising:
receiving a data stream;
generating an FSK modulated signal by dividing at least a portion of the data stream into three channels and modulating each of the separated data streams using a Mary-Frequency Shift Keying (M-FSK) method, wherein the channel for the same bit code The frequencies mapped to each are different;
synthesizing a plurality of FSK modulated signals modulated on the three channels, respectively, and generating a color modulated signal based on a preset bit-color mapping table; and
Transmitting the color modulation signal by controlling a light source of the same optical channel based on the color modulation signal,
The generating of the FSK modulated signal comprises:
Further comprising the step of modulating the separated data stream based on a preset bit-frequency mapping table,
The frequencies mapped for each channel of the bit-frequency mapping table with respect to any one bit code of the payload of the data stream are any one of a first frequency band, a second frequency band, and a third frequency band, wherein the second frequency band and the third frequency band are frequency bands separated by the same difference from the first frequency band, respectively,
Optical signal transmission method.
a light source including a color LED;
a modulator for modulating an input signal; and
A control unit for controlling the light source unit to transmit a modulated transmission signal,
The modulator divides at least a portion of the received data stream into three channels, modulates the separated data streams by a Mary-Frequency Shift Keying (M-FSK) method, respectively, to generate an FSK modulation signal, and to the same bit code. For each channel, frequencies mapped for each channel are different, a plurality of FSK modulated signals modulated in each of the three channels are synthesized, and a color modulated signal is generated based on a preset bit-color mapping table, and based on the color modulated signal to control the light source of the same optical channel to transmit the color modulation signal,
The modulator,
further configured to generate the color modulated signal based on a level signal at the same position on the time axis in a plurality of the FSK modulated signals in the form of a pulse wave,
Optical signal transmission device.
8. The method of claim 7,
The modulator,
after converting the level signal of a plurality of the FSK modulated signals into bits, concatenate the converted bits to generate the color modulated signal,
Optical signal transmission device.
a light source including a color LED;
a modulator for modulating an input signal; and
A control unit for controlling the light source unit to transmit a modulated transmission signal,
The modulator divides at least a portion of the received data stream into three channels, modulates the separated data streams by a Mary-Frequency Shift Keying (M-FSK) method, respectively, to generate an FSK modulation signal, and to the same bit code. For each channel, frequencies mapped for each channel are different, a plurality of FSK modulated signals modulated in each of the three channels are synthesized, and a color modulated signal is generated based on a preset bit-color mapping table, and based on the color modulated signal to control the light source of the same optical channel to transmit the color modulation signal,
The modulator,
The data stream separated based on a preset bit-frequency mapping table is modulated, and a preamble of the data stream is mapped to a frequency of a lowest band or a frequency of a highest band in the bit-frequency mapping table. further configured to generate an FSK modulated signal;
Optical signal transmission device.
10. The method of claim 9,
The modulator,
In the bit-frequency mapping table, the payload of the data stream maps frequencies located at equal band intervals between a frequency of the lowest band and a frequency of the highest band to a frequency of one channel to obtain the FSK modulated signal. further configured to generate
Optical signal transmission device.
10. The method of claim 9,
The modulator,
In the bit-frequency mapping table, after transmitting a color modulated signal in which an FSK modulated signal to which a frequency of the lowest band and a frequency of the highest band is mapped is transmitted, the color modulated based on the payload of the data stream further configured to transmit a modulated signal,
Optical signal transmission device.
a light source including a color LED;
a modulator for modulating an input signal; and
A control unit for controlling the light source unit to transmit a modulated transmission signal,
The modulator divides at least a portion of the received data stream into three channels, modulates the separated data streams by a Mary-Frequency Shift Keying (M-FSK) method, respectively, to generate an FSK modulation signal, and to the same bit code. For each channel, frequencies mapped for each channel are different, a plurality of FSK modulated signals modulated in each of the three channels are synthesized, and a color modulated signal is generated based on a preset bit-color mapping table, and based on the color modulated signal to control the light source of the same optical channel to transmit the color modulation signal,
The modulator,
further configured to modulate the separated data stream based on a preset bit-frequency mapping table,
The frequencies mapped for each channel of the bit-frequency mapping table with respect to any one bit code of the payload of the data stream are any one of a first frequency band, a second frequency band, and a third frequency band, wherein the second frequency band and the third frequency band are frequency bands separated by the same difference from the first frequency band, respectively,
Optical signal transmission device.
An optical signal receiving method in which a processor of a signal receiving device including a camera performs at least a part of each step,
generating a grayscale image frame based on a sensor signal of the camera photographing a light source including a color LED;
generating an FSK-modulated signal by extracting grayscale level information from an area in which the light source is photographed in the grayscale image frame;
extracting a frequency by Fourier transforming the FSK modulated signal; and
Demodulating the FSK modulated signal using a Mary-Frequency Shift Keying (M-FSK) method based on a preset bit-frequency mapping table and the frequency to generate a data stream,
The generating of the data stream comprises:
The method further comprises demodulating a frequency of a lowest band and a frequency of a highest band among the extracted frequencies into a bit code of a preamble of the data stream,
How to receive an optical signal.
14. The method of claim 13,
The generating of the data stream comprises:
The method further comprising demodulating frequencies located at equal band intervals between frequency bands corresponding to the preamble into bit codes of a payload of the data stream,
How to receive an optical signal.
a camera for generating an image by receiving an optical signal;
at least one processor; and
It is electrically connected to the processor and includes a memory in which at least one code (code) executed by the processor is stored,
The memory, when executed by the processor, causes the processor to:
A grayscale image frame is generated based on a sensor signal of the camera photographing a light source including a color LED, and grayscale level information is extracted from the area where the light source is photographed in the grayscale image frame to generate an FSK modulation signal and Fourier transform the FSK modulated signal to extract a frequency, and demodulate the FSK modulated signal based on a preset bit-frequency mapping table and the frequency in an M-FSK (Mary-Frequency Shift Keying) method to obtain a data stream a code causing to generate is stored, wherein the bit-frequency mapping table includes mapping of three different frequencies to any one identical bit code;
Optical signal receiving device.
16. The method of claim 15,
Each of the three different frequencies is any one of a first frequency band, a second frequency band, and a third frequency band, and the second frequency band and the third frequency band are respectively separated by the same difference from the first frequency band frequency bands in
Optical signal receiving device.
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