Signal modulation method, signal demodulation method and screen projection method

Abstract

The embodiment of the invention relates to the technical field of communication, and discloses a signal modulation method, a signal demodulation method and a screen projection method. The signal modulation method comprises the following steps: converting a screen transmission code into a binary sequence; wherein the screen transmission code comprises a plurality of characters, each character corresponds to a binary bit number, the binary sequence comprises a plurality of binary bits, and each binary bit maps a corresponding frequency point; and determining a frequency point sequence corresponding to the binary sequence based on the binary sequence and the frequency point corresponding to each binary bit. According to the method, before screen projection, the screen transmission code is modulated into the frequency point sequence, so that the data can be sent out at one time, the difference of front and back symbols on a time domain does not exist, the influence of a multipath effect is avoided, the transmission efficiency is high, and the sending time is shorter.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of communication technology, and in particular to a signal modulation method, a signal demodulation method, and a screen projection method. Background Art

[0002] When some ultrasonic transmission technologies are used to transmit the secret key for connection pairing, there are sequential modulation signals in the timing, such as Figure 1 As shown, in order to solve the overlapping problem of the front and rear signals, the signal time needs to be extended to avoid mutual interference between the front and rear signal characters, so the transmission time is relatively long. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a signal modulation method, a demodulation method and a screen projection method, which are modulated into a frequency point sequence, so that the data can be sent out at one time. There is no difference between the front and back symbols in the time domain, so it is not affected by the multipath effect, the transmission efficiency is high, and the sending time is shorter.

[0004] To solve the above technical problems, the embodiments of the present application adopt the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides a signal modulation method, which is applied to a device receiving screen projection, and the method includes:

[0006] Convert the screen transmission code into a binary sequence; wherein the screen transmission code includes a plurality of characters, each character corresponds to a binary bit, the binary sequence includes a plurality of binary bits, and each of the binary bits maps to a corresponding frequency point;

[0007] A frequency point sequence corresponding to the binary sequence is determined based on the binary sequence and the frequency point corresponding to each binary bit.

[0008] In some embodiments, the frequency point corresponding to the binary bit of the character is determined based on the first sound wave frequency range, the number of characters in the screen transmission code and the number of binary bits corresponding to each character.

[0009] In some embodiments, the number of binary bits corresponding to each character is determined based on a generation rule of the screen transmission code.

[0010] In some embodiments, the step of determining the frequency point corresponding to the binary bit of the character includes:

[0011] Calculating the number of frequency points based on the number of characters and the number of binary digits;

[0012] Within the first sound wave frequency range, each binary bit of each of the characters is mapped to a frequency point based on the number of frequency points.

[0013] In some embodiments, the calculating the number of frequency points based on the number of characters and the number of binary digits includes:

[0014] Accumulate the binary digits of all the characters to determine the bits of the transmission bandwidth occupied by the screen transmission code;

[0015] The number of frequency points is determined based on the bit position.

[0016] In some embodiments, the screen transmission code also includes a communication data verification code, and the bits of the communication data verification code occupied by the transmission bandwidth are determined according to the maximum value of the accumulated binary bit number of each character.

[0017] In some embodiments, mapping each binary bit of each character to a frequency point based on the number of frequency points within the first sound wave frequency range includes:

[0018] Calculating a frequency point interval based on the number of frequency points and the first sound wave frequency range;

[0019] In the first sound wave frequency range, frequency points of the number of frequency points are inserted according to the frequency point interval, and each binary bit of each character corresponds to a frequency point.

[0020] In some embodiments, the determining, based on the binary sequence and the frequency point corresponding to each binary bit, a frequency point sequence corresponding to the binary sequence includes:

[0021] Based on the binary sequence, the frequencies of the frequency sequence are arranged in order of binary bits from low to high. If the binary bit of the frequency mapping is 1, the frequency is retained; if the binary bit of the frequency mapping is 0, the frequency is removed.

[0022] In a second aspect, the present application further provides a signal demodulation method, which is applied to a screen projection device, and the method includes:

[0023] Collecting a modulation signal, wherein the modulation signal is the frequency point sequence described in the first aspect;

[0024] Performing fast Fourier transform on the binary bits corresponding to the frequency points in the frequency point sequence to obtain a binary sequence.

[0025] In a third aspect, the present application further provides a screen projection method, which is applied to a screen projection device, and the method includes:

[0026] Initiate screen projection request via Bluetooth;

[0027] Receive and mediate the ultrasonic broadcast initiated by the device receiving the screen projection based on the screen projection request to obtain the screen projection code;

[0028] Establishing a screen projection connection between the screen projection device and the device receiving the screen projection based on the screen projection code;

[0029] Wherein, the ultrasonic broadcast is transmitted based on the frequency sequence described in the first aspect.

[0030] In a fourth aspect, the present application further provides a screen projection method, which is applied to a device receiving a screen projection, and is characterized in that the method includes:

[0031] Upon receiving a screen projection request, transmitting an ultrasonic broadcast based on a frequency point sequence, wherein the frequency point sequence is modulated by the signal modulation method described in the first aspect;

[0032] After determining that the screen projection device obtains the screen projection code based on the ultrasonic wave, when establishing a screen projection connection with the device receiving the screen projection, stop transmitting the ultrasonic wave broadcast.

[0033] In a fifth aspect, the present application further provides a device for receiving screen projection, the device for receiving screen projection comprising:

[0034] A first processor and a first memory communicatively connected to the first processor;

[0035] The first memory stores computer program instructions, and when the computer program instructions are called by the first processor, the first processor executes the method as described in any one of the first aspect and the fourth aspect.

[0036] In a sixth aspect, the present application further provides a screen projection device, the screen projection device comprising:

[0037] a second processor and a second memory communicatively connected to the second processor;

[0038] The second memory stores computer program instructions, and when the computer program instructions are called by the second processor, the second processor executes the method as described in any one of the second and third aspects.

[0039] In the seventh aspect, the present application also provides a non-volatile computer-readable storage medium, which stores computer-executable instructions. When the computer-executable instructions are executed by an electronic device, the steps of the signal modulation method described in the first aspect, the steps of the signal demodulation method described in the second aspect, and the steps of the screen projection method described in the third and fourth aspects are implemented.

[0040] Beneficial effects of the embodiments of the present application: Different from the prior art, the signal modulation method, signal demodulation method and screen projection method provided by the embodiments of the present application, wherein signal modulation is performed before transmitting the screen projection code, and the screen transmission code is converted into a binary sequence; wherein the screen transmission code includes a plurality of characters, each character corresponds to a binary digit, the binary sequence includes a plurality of binary bits, and each of the binary bits maps to a corresponding frequency point; the frequency point sequence corresponding to the binary sequence is determined based on the binary sequence and the frequency point corresponding to each binary bit. The screen transmission code is transmitted in the form of a frequency point sequence, but is modulated in the frequency domain, which is independent of the time domain. Therefore, the signal at any time in the time domain is maintained, and when receiving the frequency point sequence and demodulating it, it can be determined whether the frequency point at a specific position exists and then determine the binary stream, thereby solving the problem of signal time extension caused by signal overlap.

[0041] Moreover, since the screen transmission code is modulated into a frequency sequence, the data can be sent out at one time. There is no difference between the previous and next symbols in the time domain. Therefore, it is not affected by the multipath effect, the transmission efficiency is high, and the sending time is shorter. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0043] Figure 1 It is a schematic diagram of the multipath effect of the prior art;

[0044] Figure 2 This is a schematic diagram of the scenario in which the device receiving the screen projection interacts with the screen projection device in this application;

[0045] Figure 3 It is a flow chart of an embodiment of the signal modulation method of the present application;

[0046] Figure 4 It is a flowchart of an embodiment of the signal demodulation method of the present application;

[0047] Figure 5 It is a flowchart of an embodiment of the screen projection method of the present application;

[0048] Figure 6 It is a flowchart of another embodiment of the screen projection method of the present application;

[0049] Figure 7 It is a structural schematic diagram of an embodiment of the signal modulation device of the present application;

[0050] Figure 8It is a structural schematic diagram of an embodiment of the signal demodulation device of the present application;

[0051] Fig. 9 It is a structural schematic diagram of an embodiment of the screen projection device of the present application;

[0052] Fig.10 It is a structural schematic diagram of another embodiment of the screen projection device of the present application;

[0053] Fig.11 This is a schematic diagram of the hardware structure of a controller in one embodiment of a device for receiving screen projection in the present application;

[0054] Fig.12 This is a schematic diagram of the hardware structure of the controller in one embodiment of the screen projection device of the present application. DETAILED DESCRIPTION

[0055] The present application is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements can also be made without departing from the concept of the present application. These all belong to the protection scope of the present application.

[0056] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0057] It should be noted that, if there is no conflict, the various features in the embodiments of the present application can be combined with each other, all within the scope of protection of the present application. In addition, although the functional module division is performed in the device schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a sequence different from the module division in the device or the flow chart. In addition, the words "first", "second", "third", etc. used herein do not limit the data and execution order, but only distinguish the same items or similar items with basically the same functions and effects.

[0058] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0059] In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0060] The signal modulation method and apparatus provided in the embodiments of the present application can be applied to a device for receiving screen projection. The device for receiving screen projection in the present application can be a display screen during a meeting, or an electronic device with a larger screen such as a television, but is not limited here.

[0061] The signal demodulation method and device provided in the embodiments of the present application can be applied to a screen projection device, which may be a personal computer, a smart pen, a smart phone, etc., but is not limited thereto.

[0062] In some embodiments, when the screen projection device projects the screen to the device receiving the projection, the device receiving the projection acts as the transmitter. The transmitter first performs time domain modulation on the projection code, and then sends out each character of the projection code in sequence. The screen projection device, as the receiver, can receive the direct signal directly sent by the transmitter, and can also receive the reflected signal reflected by the surrounding environment. The reflected signal is the signal transmitted by the transmitter, and the signal is reflected by the object (such as a wall) in the space. Since the transmitted signal reaches the receiver through multiple different paths, and these paths are of different lengths, the reflected signal will arrive later than the direct signal. In a space, the maximum reflection delay is determined by the reflection path. Therefore, the receiver will be significantly affected by the multipath effect. Figure 1 As shown, in the prior art, taking the conference room scenario as an example, the reflected signal received by the receiving end is delayed by up to 50ms compared to the direct signal. Therefore, the sampling of each character bit of the projection code by the receiving end needs to be delayed by more than 50ms before it can be correctly sampled. The longer the duration of the character bit of the projection code after timing modulation, the wider the sampling position of the character bit will be, and the greater the sampling margin will be. When the receiving end receives the direct signal at one moment, it will also receive the reflected signal at the next moment, and the signals at the previous and next moments are different, so the signals are confused when they are superimposed, causing overlapping interference of the previous signal at the sampling position. If the overlapping interference problem of the previous and next signals is to be solved, the sampling signal time needs to be extended, such as Figure 1 The sampling position shown is the correct sampling position, which can avoid mutual interference between the previous and next characters, but it will cause a longer transmission time.

[0063] In order to solve the above problems, Figure 2 As shown, Figure 2It is a schematic diagram of a scenario in which a device receiving screen projection interacts with a screen projection device. The device receiving screen projection 100 may be a large-screen terminal 100 in a conference room scenario or a home scenario, such as an interactive intelligent panel (IIP), a projector, a TV, etc. The screen projection device 200 may be a personal computer, a smart pen, a smart phone, etc. When the screen projection device 200 establishes a screen projection connection with the device receiving screen projection 100, the screen projection device 200 initiates a screen projection request via Bluetooth. When the device receiving screen projection 100 receives the screen projection request, it modulates a frequency sequence and transmits an ultrasonic broadcast based on the frequency sequence, and may transmit an ultrasonic wave based on a speaker terminal device 300. The screen projection device 200 may collect and demodulate the ultrasonic wave through a microphone to obtain a screen projection code, so that the device receiving screen projection 100 may establish a screen projection connection with the screen projection device 200.

[0064] Since the broadcast initiated by screen projection is ultrasonic broadcast, and before screen projection, the screen transmission code is modulated into a frequency point sequence at one time, which is a frequency domain signal. When the ultrasonic broadcast is transmitted based on the modulated frequency point sequence, since it is a modulation in the frequency domain and there is no modulation in the time domain, the frequencies in the frequency point sequence can be sent out at the same time. When the device 100 receiving the screen projection receives the frequency point sequence, it receives it at one time. There is no difference in the receiving time of the front and rear symbols in the screen transmission code in the time domain. Therefore, it is not affected by the multipath effect, has a high transmission rate, and a short sending time.

[0065] See also Figure 3 , Figure 3 This is a flow chart of an embodiment of a signal modulation method applied to the present application. The signal modulation method can be executed by a controller in a device 100 for receiving screen projection, and the method includes steps S301 and S302.

[0066] S301: Convert the screen transmission code into a binary sequence, wherein the screen transmission code includes a plurality of characters, each character corresponds to a binary bit, the binary sequence includes a plurality of binary bits, and each binary bit maps a corresponding frequency point.

[0067] The screen transmission code usually includes multiple characters. Before the device receiving the screen projection modulates the screen transmission code, the number of characters in the screen transmission code is usually fixed. For example, the number of characters in the screen transmission code is 6 bits, or it can be 8 bits or 10 bits, etc., which is not limited here.

[0068] Characters refer to glyph units or symbols, including letters, numbers, operation symbols, punctuation marks and other symbols, as well as some functional symbols. Characters are the general term for letters, numbers, and symbols in electronic computers or radio communications. For example, the screen transmission code is MA27ZX. Then, the number of characters in the screen transmission code is 6 characters.

[0069] Furthermore, the number of binary bits corresponding to each character can be determined based on the generation rule of the screen transmission code.

[0070] For example, the generation rule is: the characters of the screen transmission code can only be uppercase letters AZ and 0-9, and do not contain 0 and O, 1 and I that are easily misidentified, so there are only 32 character representations in total. Then, the screen transmission code only needs 6 bits to complete the binary mapping of the screen transmission code, and the binary digits corresponding to each character are six binary bits. At this time, the character A can correspond to 1, and the six-bit binary representation is 000 001, the character B can correspond to 2, and the six-bit binary representation is 000 010, and so on, the character Z can correspond to 24, and the six-bit binary representation is 011 000; the digital character 2 can be represented as 2, and the six-bit binary representation is 011 001, and the digital character 9 can be represented as 32, and the six-bit binary representation is 100 000.

[0071] If the generation rule is that the characters of the screen transmission code can only be represented by the numbers 0 to 7, then each digital character only needs 3 bits to represent it, and three bits of binary are used to represent 8 states. In this case, the number of binary bits is three bits of binary.

[0072] Therefore, if the generation rules are changed to include special symbols, lowercase letters, etc., there will be more types of characters. Then, the screen code may also require 8 bits to represent a character. For example, if the screen code is MA27ZX, each character is represented by eight bits of binary, then the character M is represented by eight bits of binary as 0100 1101.

[0073] In some of the embodiments, in order to realize the frequency point corresponding to each binary bit mapping, the frequency point corresponding to the binary bit of the character is determined based on the first sound wave frequency range, the number of characters in the screen transmission code and the number of binary bits corresponding to each character.

[0074] The first sound wave frequency range can be selected as 18.5kHz-22kHz. If the data amount of the transmitted screen code is small, the sound wave frequency range of 20kHz-22kHz can be selected as the first sound wave frequency range. There is no limitation here.

[0075] Moreover, the human ear cannot hear sound waves exceeding 20Khz during the transmission process, so it will not affect the user when projecting the screen.

[0076] In some implementations, the step of determining the frequency points corresponding to the binary bits of the characters may include:

[0077] Calculate the number of frequency points based on the number of characters and the number of binary digits;

[0078] Within the first sound wave frequency range, each binary bit of each character is mapped to a frequency point based on the number of frequency points.

[0079] Specifically, the number of frequency points is calculated first, and then frequency points of the number of frequency points are inserted within the frequency range of the first sound wave, so that each binary bit of each character is mapped to a frequency point.

[0080] To calculate the number of frequency points, in some implementations, the number of frequency points is calculated based on the number of characters and the number of binary digits, including:

[0081] Accumulate the binary digits of all characters to determine the bits of transmission bandwidth occupied by the screen transmission code;

[0082] The number of frequency points is determined based on the bit position.

[0083] Specifically, in order to determine the number of frequency points, after determining the number of binary bits corresponding to each character; accumulate the binary bits of all characters to determine the bits of the transmission bandwidth occupied by the screen transmission code; and determine the number of frequency points based on the bits.

[0084] For example, taking the screen projection code MA27ZX as an example, the number of characters is 6 characters. If the binary bit number is eight binary bits, then 8 frequency points are used to represent one character. The accumulated binary bit number of the 6 characters is the total binary bit number of the screen projection code, which is 6*8=48. The total binary bit number is used as the bit number of the transmission bandwidth occupied by the screen transmission code, which is 48 bits. The number of frequency points corresponds to the total binary bit number, which is also 48. Therefore, 48 frequency points are required to transmit the screen transmission code.

[0085] In some implementations, the screen transmission code also includes a communication data verification code, and the bits of the communication data verification code that occupy the transmission bandwidth are determined according to the maximum value of the accumulated binary bit number of each character.

[0086] Specifically, the screen transmission code may include a communication data verification code in addition to the key. For example, the screen transmission code is MA27ZX, and each character is represented by six-bit binary, as shown in Table 1:

[0087]

[0088] Table 1

[0089] Among them, check_sum is a commonly used communication data check code, which is the cumulative sum of the first 6 characters.

[0090] The maximum value of 6 characters is 32*6=192, so the communication data check check_sum can be in eight-bit binary.

[0091] Therefore, the transmission of MA27ZX with communication data check code requires a total of 6*6+8=44 bits, so the number of frequency points is 44, and the first sound wave frequency range (18.5KHZ-22KHZ) can be evenly inserted into 44 frequency points.

[0092] After the number of frequency points is determined, each binary bit of each character is mapped to a frequency point within the first sound wave frequency range based on the number of frequency points.

[0093] In some embodiments, within the first sound wave frequency range, mapping each binary bit of each character to a frequency point based on the number of frequency points may include:

[0094] Calculate the frequency point interval based on the number of frequency points and the frequency range of the first sound wave;

[0095] Frequency points of the same number as the frequency points are inserted within the first sound wave frequency range according to the frequency point interval, and each binary bit of each character corresponds to a frequency point.

[0096] Specifically, in order to achieve frequency transmission, it is necessary to determine the frequency mapped to each binary bit of the character. Based on the number of frequency points and the first sound wave frequency range, the frequency point interval is calculated. For example, if the number of frequency points is 48 and the first sound wave frequency range is 18.5KHZ-22KZ, then the frequency band is (22K-18.5K) Hz = 3.5KHz. In order to insert the frequency points evenly, the frequency band is divided by the number of frequency points to obtain the frequency point interval, that is, 3.5KHZ / 48≈73HZ. Therefore, the frequency point interval can be taken as 70HZ, which can meet the insertion of 48 frequency points within the range of 18.5KHZ-22KZ.

[0097] The 48 frequencies are:

[0098] CH1=[18500,18570,18640,18710,18780,18850,18920,18990],

[0099] CH2=[19060,19130,19200,19270,19340,19410,19480,19550],

[0100] CH3=[19620,19690,19760,19830,19900,19970,20040,20110],

[0101] CH4=[20180,20250,20320,20390,20460,20530,20600,20670],

[0102] CH5=[20740,20810,20880,20950,21020,21090,21160,21230],

[0103] CH6=[21300,21370,21440,21510,21580,21650,21720,21790].

[0104] There are 48 frequencies, each group consists of 8 frequencies, increasing from 18500HZ to 21790HZ.

[0105] Taking the screen transmission code MA27ZX as an example, the corresponding ASCII codes are shown in Table 2:

[0106]

[0107] Among them, M = 77, which is expressed as 0100 1101 in eight-bit binary;

[0108] The corresponding frequency point is CH1 = [18500, 18570, 18640, 18710, 18780, 18850, 18920, 18990], thereby obtaining the frequency point mapped to each binary bit of each character, that is, in CH1, the first binary bit is 0, the corresponding frequency point is 18500, the second binary bit is 1, the corresponding frequency point is 18570, and so on.

[0109] When projecting the screen, the transmission screen code will modulate the projection code to obtain a frequency point sequence. Since the audio sampling rate is 48KHZ, in order to achieve a spectrum resolution of ≤70HZ, the number of sampling points on the receiving end needs to satisfy N≥48000 / 70=686 points. Therefore, when demodulating the signal, the receiving end collects the modulated signal, and the modulated signal is the above-mentioned frequency point sequence; the binary bits corresponding to the frequency points in the frequency point sequence are fast Fourier transformed to obtain a binary sequence.

[0110] When performing fast Fourier transform FFT, the slicing time needs to be T≥686 / 48000*1000=14.3ms.

[0111] Therefore, when the screen transmission code is converted into a binary sequence, for example, the first character M of the screen transmission code MA27ZX is converted into an eight-bit binary sequence of 0100 1101. Correspondingly, all characters of the screen transmission code are converted into eight-bit binary.

[0112] S302: Determine a frequency point sequence corresponding to the binary sequence based on the binary sequence and the frequency point corresponding to each binary bit.

[0113] In some implementations, determining a frequency point sequence corresponding to the binary sequence based on the binary sequence and the frequency point corresponding to each binary bit may include:

[0114] Based on the binary sequence, the frequencies of the frequency point sequence are arranged in order of binary bits from low to high. If the binary bit of the frequency point mapping is 1, the frequency point is retained. If the binary bit of the frequency point mapping is 0, the frequency point is removed.

[0115] For example, the first character M of the screen transmission code MA27ZX has a binary sequence of 0100 1101. The frequency point sequence is arranged in the order of binary bits from low to high, which is CH1 = [18500, 18570, 18640, 18710, 18780, 18850, 18920, 18990]. If the binary bit of the frequency point mapping is 1, the frequency point is retained. If the binary bit of the frequency point mapping is 0, the frequency point is removed. Obviously, if the first binary bit of the first character M is 0, then the corresponding first frequency point 18500 is removed; if the second binary bit is 1, then the corresponding second frequency point 18570 is retained, and so on, so that the frequency point sequence of the first character M is CH = [18570, 18780, 18850, 18990].

[0116] Therefore, the binary number corresponding to the complete MA27ZX is [0100 1101 0100 0001 00110010 00110011 0101 1010 0101 1000]. To send MA27ZX, the sending frequency is CH = [18570, 18780, 18850, 18990, 19130, 19550, 19760, 19830, 20040, 20320, 20390, 20600, 20670, 20810, 20950, 21020, 21160, 21370, 21510, 21580].

[0117] Since the screen transmission code of this application is modulated into a frequency point sequence, it is transmitted in the form of a frequency point sequence. It is only modulated in the frequency domain and has nothing to do with the time domain. Therefore, the signal at any time in the time domain is maintained. When receiving the frequency point sequence and demodulating it, it can be determined whether the frequency point at a specific position exists and then determine the binary stream, thereby solving the problem of signal time extension caused by signal overlap.

[0118] In the embodiment of the present application, when transmitting the screen projection code, since the screen transmission code is modulated into a frequency point sequence, the data can be sent out at one time, and there is no difference between the front and back symbols in the time domain. Therefore, it is not affected by the multipath effect, the transmission efficiency is high, and the sending time is shorter.

[0119] Calculations show that when the screen transmission code has 6 characters, the minimum sending time is only 14.3ms, which is the minimum time length of a single frame.

[0120] like Figure 4As shown, an embodiment of the present application also provides a signal demodulation method, which is applied to a screen projection device, and the signal demodulation method includes steps S401 to S402.

[0121] S401: Collect a modulation signal, where the modulation signal is the above frequency point sequence.

[0122] S402: Perform fast Fourier transform on binary bits corresponding to the frequency points in the frequency point sequence to obtain a binary sequence.

[0123] The signal demodulation method of the present application captures the frequency point sequence obtained by the ultrasonic broadcast emitted in the air based on the signal modulation method, demodulates the binary sequence corresponding to the frequency point sequence, thereby realizing signal demodulation and avoiding mutual interference between previous and next characters.

[0124] like Figure 5 As shown, an embodiment of the present application also provides a screen projection method, which is applied to a screen projection device, and the method includes steps S501 to S503.

[0125] S501: Initiate screen projection request via Bluetooth;

[0126] S502: Receive and mediate the ultrasonic broadcast initiated by the device receiving the screen projection based on the screen projection request to obtain the screen projection code;

[0127] S503: Establishing a screen projection connection between the screen projection device and the device receiving the screen projection based on the screen projection code;

[0128] Among them, the ultrasonic broadcast is transmitted based on the above-mentioned frequency sequence.

[0129] like Figure 6 As shown, an embodiment of the present application also provides a screen projection method, which is applied to a device receiving the screen projection, and the method includes steps S601 to S602.

[0130] S601: upon receiving a screen projection request, transmitting ultrasonic broadcasting based on a frequency sequence, where the frequency sequence is modulated by the aforementioned signal modulation method;

[0131] S602: After determining that the screen projection device obtains the screen projection code based on ultrasound, when establishing a screen projection connection with the device receiving the screen projection, stop transmitting ultrasonic broadcasts.

[0132] Specifically, the screen projection request initiates a beacon frame via Bluetooth. After the screen projection device initiates the screen projection request, the device receiving the screen projection receives the screen projection request and emits an ultrasonic broadcast based on the frequency sequence; the screen projection device receives and demodulates the ultrasonic broadcast to obtain the screen projection code, and the screen projection device establishes a screen projection connection between the screen projection device and the device receiving the screen projection based on the screen projection code. After the device receiving the screen projection determines that the screen projection device has obtained the screen projection code based on the ultrasonic wave, it stops emitting ultrasonic broadcasts when establishing a screen projection connection with the device receiving the screen projection, thereby completing the screen projection connection between the screen projection device and the device receiving the screen projection.

[0133] The screen projection method of the present application is similar to the screen projection method of the prior art, except that the broadcast initiated by the screen projection is an ultrasonic broadcast, and the ultrasonic broadcast is transmitted based on a modulated frequency sequence, so the data can be sent out at one time, and there is no difference between the front and back symbols in the time domain. Therefore, it is not affected by the multipath effect, has a high transmission rate, and a short transmission time.

[0134] The present application also provides a signal modulation device for use in a device that receives screen projection. Figure 7 , which shows the structure of a signal modulation device provided in an embodiment of the present application, the signal modulation device 700 includes:

[0135] A conversion module 701, used for converting the screen transmission code into a binary sequence;

[0136] The frequency point sequence module 702 is used to determine a frequency point sequence corresponding to the binary sequence based on the binary sequence and the frequency point corresponding to each binary bit.

[0137] In the embodiment of the present application, when transmitting the screen projection code, since the screen transmission code is modulated into a frequency point sequence, the data can be sent out at one time, and there is no difference between the front and back symbols in the time domain. Therefore, it is not affected by the multipath effect, the transmission efficiency is high, and the sending time is shorter.

[0138] In some embodiments, the frequency point corresponding to the binary bit of the character is determined based on the first sound wave frequency range, the number of characters in the screen transmission code and the number of binary bits corresponding to each character.

[0139] In some embodiments, the number of binary bits corresponding to each character is determined based on a generation rule of the screen transmission code.

[0140] In some embodiments, the signal modulation apparatus 700 further includes a frequency point determination module 703, which is used to:

[0141] Calculate the number of frequency points based on the number of characters and the number of binary digits;

[0142] Within the first sound wave frequency range, each binary bit of each character is mapped to a frequency point based on the number of frequency points.

[0143] In some embodiments, the frequency determination module 703 is further configured to:

[0144] Accumulate the binary digits of all characters to determine the bits of transmission bandwidth occupied by the screen transmission code;

[0145] The number of frequency points is determined based on the bit position.

[0146] In some embodiments, the screen transmission code also includes a communication data verification code, and the bits of the communication data verification code occupying the transmission bandwidth are determined according to the maximum value of the accumulated binary bit number of each character.

[0147] In some embodiments, the frequency determination module 703 is further configured to:

[0148] Calculate the frequency point interval based on the number of frequency points and the frequency range of the first sound wave;

[0149] Frequency points of the same number as the frequency points are inserted within the first sound wave frequency range according to the frequency point interval, and each binary bit of each character corresponds to a frequency point.

[0150] In some embodiments, the frequency point sequence module 702 is further configured to:

[0151] Based on the binary sequence, the frequencies of the frequency point sequence are arranged in order of binary bits from low to high. If the binary bit of the frequency point mapping is 1, the frequency point is retained. If the binary bit of the frequency point mapping is 0, the frequency point is removed.

[0152] The present application also provides a signal demodulation device for use in a screen projection device. Figure 8 , which shows the structure of a signal modulation device provided in an embodiment of the present application, the signal demodulation device 800 includes:

[0153] The acquisition module 801 is used to acquire the modulation signal, where the modulation signal is the frequency point sequence mentioned above;

[0154] The transformation module 802 is used to perform fast Fourier transformation on the binary bits corresponding to the frequency points in the frequency point sequence to obtain a binary sequence.

[0155] The present application also provides a screen projection device, which is applied to a screen projection device. Fig. 9 , which shows the structure of a screen projection device provided in an embodiment of the present application, the screen projection device 900 includes:

[0156] A request initiating module 901 is used to initiate a screen projection request via Bluetooth;

[0157] The demodulation module 902 is used to receive and modulate the ultrasonic broadcast initiated by the device receiving the screen projection based on the screen projection request to obtain the screen projection code;

[0158] A connection module 903 is used to establish a screen projection connection between the screen projection device and the device receiving the screen projection based on the screen projection code;

[0159] Among them, the ultrasonic broadcast is transmitted based on the frequency sequence as mentioned above.

[0160] The present application also provides a screen projection device for use with a device that receives a screen projection. Fig.10 , which shows the structure of a screen projection device provided in an embodiment of the present application, the screen projection device 1000 includes:

[0161] The request receiving module 1001 is used to transmit ultrasonic broadcast based on a frequency sequence when receiving a screen projection request, and the frequency sequence is modulated by the above-mentioned signal modulation method;

[0162] The stop module 1002 is used to stop transmitting ultrasonic broadcasts when it is determined that the screen projection device obtains the screen projection code based on ultrasonic waves and establishes a screen projection connection with the device receiving the screen projection.

[0163] It should be noted that the above device can execute the method provided in the embodiment of the present application, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not fully described in the device embodiment, please refer to the method provided in the embodiment of the present application.

[0164] Fig.11 FIG. 1 is a schematic diagram of the hardware structure of a controller of a device 100 for receiving screen projection in one embodiment of a device for receiving screen projection, such as Fig.11 As shown, the first controller includes:

[0165] One or more first processors 111 and a first memory 112 . Fig.11 In the figure, a first processor 111 and a first memory 112 are taken as an example.

[0166] The first processor 111 and the first memory 112 may be connected via a bus or other means. Figure 6 The example of connecting through bus is taken in the following.

[0167] The first memory 112 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs and modules, such as program instructions / modules corresponding to the signal modulation method in the embodiment of the present application (for example, the attached Figure 7 The conversion module 701, the frequency sequence module 702, the frequency determination module 703) and the program instructions / modules corresponding to the screen projection method in the embodiment of the present application (for example, the attached Fig.10The first processor 111 executes various functional applications and data processing of the controller by running the non-volatile software programs, instructions and modules stored in the first memory 112, that is, the signal modulation method of the above method embodiment is implemented.

[0168] The first memory 112 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and applications required for at least one function; the data storage area may store data created according to the use of a personnel entry and exit detection device, etc. In addition, the first memory 112 may include a high-speed random access first memory, and may also include a non-volatile first memory, such as at least one disk first storage device, a flash memory device, or other non-volatile solid-state first storage device. In some embodiments, the first memory 112 may optionally include a first memory remotely disposed relative to the first processor 111, and these remote first memories may be connected to a device receiving the projection via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0169] The one or more modules are stored in the first memory 112, and when executed by the one or more first processors 111, perform the signal modulation method in any of the above method embodiments, for example, perform the signal modulation method described above. Figure 3 Steps S301 to S302 of the method; implementing Figure 7 Modules 701-704 and Fig.10 The functions of modules 1001-1002 in FIG.

[0170] Accordingly, Fig.12 FIG. 1 is a schematic diagram of the hardware structure of a controller of a screen projection device 200 in one embodiment of the screen projection device. Fig.12 As shown, similar to the device receiving the screen projection, the second controller includes:

[0171] One or more second processors 211 and a second memory 212 . Fig.12 In the figure, a second processor 211 and a second memory 212 are taken as an example.

[0172] The second processor 211 and the second memory 212 may be connected via a bus or other means. Fig.12 The example of connecting through bus is taken in the following.

[0173] The hardware processing method of the screen projection device is similar to that of the device receiving the screen projection, so it will not be repeated here.

[0174] The above-mentioned product can execute the method provided in the embodiment of the present application, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not fully described in this embodiment, please refer to the method provided in the embodiment of the present application.

[0175] The embodiment of the present application provides a non-volatile computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are executed by one or more processors, such as Fig.11 A first processor 111 or Fig.12 A second processor 211 in the embodiment may enable the one or more processors to execute the signal modulation method in any of the above method embodiments, for example, to execute the signal modulation method described above. Figure 3 Steps S301 to S302 of the method, Figure 6 Steps S601 to S602 of the method, Figure 4 Steps S401 to S402 of the method, Figure 5 Method steps S501 to S503 in; implement Figure 7 Modules 701-703 in Figure 8 Modules 801-802 in Fig. 9 Functions of modules 901-903 in Fig.10 The functions of 1001-1002 in .

[0176] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0177] Through the description of the above embodiments, a person of ordinary skill in the art can clearly understand that each embodiment can be implemented by means of software plus a general hardware platform, or of course by hardware. A person of ordinary skill in the art can understand that all or part of the processes in the above embodiment methods can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above methods. Among them, the storage medium can be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0178] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A signal modulation method, applied to a device receiving screen projection, characterized in that: include: Convert the screen transmission code into a binary sequence; wherein the screen transmission code includes a plurality of characters, each character corresponds to a binary bit, the binary sequence includes a plurality of binary bits, and each of the binary bits maps to a corresponding frequency point; A frequency point sequence corresponding to the binary sequence is determined based on the binary sequence and the frequency point corresponding to each binary bit.

2. The method according to claim 1, characterized in that The frequency point corresponding to the binary bit of the character is determined based on the first sound wave frequency range, the number of characters in the screen transmission code and the number of binary bits corresponding to each character.

3. The method according to claim 2, characterized in that The number of binary bits corresponding to each character is determined based on the generation rule of the screen transmission code.

4. The method according to claim 2, characterized in that: The step of determining the frequency point corresponding to the binary bit of the character comprises: Calculate the number of frequency points based on the number of characters and the number of binary digits; Within the first sound wave frequency range, each binary bit of each of the characters is mapped to a frequency point based on the number of frequency points.

5. The method according to claim 4, characterized in that The calculating the number of frequency points based on the number of characters and the number of binary digits includes: Accumulate the binary digits of all the characters to determine the bits of the transmission bandwidth occupied by the screen transmission code; The number of frequency points is determined based on the bit position.

6. The method according to claim 5, characterized in that The screen transmission code also includes a communication data check code, and the bits of the communication data check code occupied by the transmission bandwidth are determined according to the maximum value of the accumulated binary bit numbers of each character.

7. The method according to claim 4, characterized in that Mapping each binary bit of each character to a frequency point based on the number of frequency points within the first sound wave frequency range includes: Calculating a frequency point interval based on the number of frequency points and the first sound wave frequency range; In the first sound wave frequency range, frequency points of the number of frequency points are inserted according to the frequency point interval, and each binary bit of each character corresponds to a frequency point.

8. The method according to claim 1, characterized in that: The determining, based on the binary sequence and the frequency point corresponding to each binary bit, a frequency point sequence corresponding to the binary sequence includes: Based on the binary sequence, the frequencies of the frequency sequence are arranged in order of binary bits from low to high. If the binary bit of the frequency mapping is 1, the frequency is retained; if the binary bit of the frequency mapping is 0, the frequency is removed.

9. A signal demodulation method, applied to a screen projection device, characterized in that: The method comprises: Collecting a modulation signal, wherein the modulation signal is the frequency point sequence according to claim 1; Performing fast Fourier transform on the binary bits corresponding to the frequency points in the frequency point sequence to obtain a binary sequence.

10. A screen projection method, applied to a screen projection device, characterized in that: The method comprises: Initiate screen projection request via Bluetooth; Receive and mediate the ultrasonic broadcast initiated by the device receiving the screen projection based on the screen projection request to obtain the screen projection code; Establishing a screen projection connection between the screen projection device and the device receiving the screen projection based on the screen projection code; Wherein, the ultrasonic broadcast is transmitted based on the frequency sequence as described in claim 1.

11. A screen projection method, applied to a device receiving screen projection, characterized in that: The method comprises: Upon receiving a screen projection request, transmitting an ultrasonic broadcast based on a frequency point sequence, wherein the frequency point sequence is modulated by the signal modulation method according to claim 1; After determining that the screen projection device obtains the screen projection code based on the ultrasonic wave, when establishing a screen projection connection with the device receiving the screen projection, stop transmitting the ultrasonic wave broadcast.

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