Digital selective call signal receiving method, device, equipment and medium

Abstract

The invention discloses a digital selective call signal receiving method and device, equipment and a medium, and relates to the technical field of communication, and the method comprises the steps: enabling a plurality of pieces of multi-channel digital receiving equipment to be on duty of audio signals of a plurality of target frequencies; when each multi-channel digital receiving device receives an audio signal corresponding to any target frequency, each multi-channel digital receiving device transmits the audio signal to a multi-channel digital selective call modulation and demodulation device; respectively demodulating each audio signal of the same target frequency by using a multi-channel digital selective call modulation and demodulation device so as to generate corresponding soft information; and the digital selective call diversity signal processing equipment is utilized to merge and decode the soft information to obtain a message corresponding to the audio signal. According to the invention, the audio signals of multiple frequencies are on duty through wide-area cooperation of multiple pieces of multi-channel digital receiving equipment, so that the receiving stability is improved, and short-wave communication can be realized more stably and reliably.

Description

Technical Field

[0001] This application relates to the field of communication technologies, and in particular, to a method, apparatus, device, and medium for receiving digital selective calling signals. Background Art

[0002] Digital Selective Calling (DSC) is an important means for ships to send distress alarms in the Global Maritime Distress and Safety System (GMDSS). Classified by the operating sea area, DSC is divided into VHF DSC (coastal / A1 sea area), MF DSC (medium distance / A2 sea area), and HF DSC (long distance / A3 sea area). Among them, VHF DSC operates at 156.525 MHz and transmits through space waves. Due to factors such as variable coastal weather, many building obstacles, and frequent electromagnetic interference from other wireless devices or communication systems in the frequency band, the quality of space wave transmission cannot be guaranteed; MF / HF DSC operates at 2 - 30 MHz, and the signal transmission in this frequency band mainly relies on ionospheric reflection. However, the reflection characteristics of the ionosphere change frequently in the time domain, frequency domain, and spatial domain, resulting in generally poor stability of medium and short wave communication links. DSC is a mandatory maritime alarm communication service required to be on duty by the Safety of Life at Sea (SOLAS) Convention and is an important part of GMDSS (Global Maritime Distress and Safety System). Improving the receiving system of coastal radio stations and enhancing the receiving quality of DSC alarm signals will effectively improve the search and rescue efficiency and ensure the safety of lives and property at sea. Summary of the Invention

[0003] The main purpose of the embodiments of this application is to propose a method, apparatus, device, and medium for receiving digital selective calling signals to improve the receiving stability of digital selective calling signals.

[0004] To achieve the above object, on the one hand, an embodiment of this application proposes a method for receiving digital selective calling signals, and the method includes the following steps:

[0005] Respectively monitor the audio signals of multiple target frequencies through multiple multi-channel digital receiving devices;

[0006] When each of the multi-channel digital receiving devices receives the audio signal corresponding to any of the target frequencies, use each of the multi-channel digital receiving devices to transmit the audio signal to a multi-channel digital selective calling modulation and demodulation device;

[0007] Use the multi-channel digital selective calling modulation and demodulation device to demodulate each of the audio signals of the same target frequency to generate corresponding soft information;

[0008] The digital selective calling diversity signal processing device is used to combine and then decode each of the soft information to obtain the message corresponding to the audio signal.

[0009] In some embodiments, the step of using the digital selective calling diversity signal processing device to combine and then decode each of the soft information to obtain the message corresponding to the audio signal includes the following steps:

[0010] Determine the weighting coefficients corresponding to each of the soft information, and then determine the combining method of each of the soft information as the maximum ratio combining method;

[0011] Use the digital selective calling diversity signal processing device to perform weighted combination and then decoding on each of the soft information and the corresponding weighting coefficients to obtain the message corresponding to the audio signal.

[0012] In some embodiments, the step of determining the weighting coefficients corresponding to each of the soft information and then determining the combining method of each of the soft information as the maximum ratio combining method includes the following steps:

[0013] Determine the expression of each of the audio signals as:

[0014] f i (t) = s i (t) + n i (t);

[0015] where, f i (t) represents the i-th audio signal at time t, s i (t) represents the target signal in the i-th audio signal at time t, n i (t) represents the noise signal in the i-th audio signal at time t;

[0016] Calculate the target coefficients of each of the audio signals;

[0017] The expression of the target coefficient is:

[0018]

[0019] where, k represents the target coefficient, and N is the total number of the audio signals;

[0020] Determine the weighting coefficients of each of the soft information according to the target coefficients;

[0021] The expression of the weighting coefficient is:

[0022]

[0023] where, w i represents the weighting coefficient of the i-th soft information.

[0024] In some embodiments, the method further includes the following steps:

[0025] Display the message through a display terminal; wherein, the message includes the sending time of the audio signal, the call type of the audio signal, and the coordinates of the device sending the audio signal when the audio signal is sent;

[0026] If the call type is a distress type, give an audible and visual alarm.

[0027] In some embodiments, the method further includes the following steps:

[0028] Adjust each of the target frequencies monitored by each of the multi-channel digital receiving devices.

[0029] To achieve the above object, on the other hand, an embodiment of the present application provides a digital selective call signal receiving device, the device includes:

[0030] A signal monitoring unit, configured to monitor audio signals of multiple target frequencies respectively through a plurality of multi-channel digital receiving devices;

[0031] A signal transmission unit, configured to, when each of the multi-channel digital receiving devices receives the audio signal corresponding to any of the target frequencies, use each of the multi-channel digital receiving devices to transmit the audio signal to a multi-channel digital selective call modulation and demodulation device;

[0032] A signal demodulation unit, configured to use the multi-channel digital selective call modulation and demodulation device to demodulate each of the audio signals of the same target frequency respectively to generate corresponding soft information;

[0033] A signal decoding unit, configured to use a digital selective call diversity signal processing device to merge and decode each of the soft information to obtain the message corresponding to the audio signal.

[0034] To achieve the above object, on the other hand, an embodiment of the present application provides an electronic device, the electronic device includes a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the above method is implemented.

[0035] To achieve the above object, on the other hand, an embodiment of the present application provides a computer-readable storage medium, the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above method is implemented.

[0036] The embodiments of the present application at least include the following beneficial effects:

[0037] This application can have multiple multi-channel digital receiving devices respectively monitor the audio signals of multiple target frequencies; when each multi-channel digital receiving device receives the audio signal corresponding to any target frequency, use each multi-channel digital receiving device to transmit the audio signal to the multi-channel digital selective calling modulation and demodulation device; use the multi-channel digital selective calling modulation and demodulation device to demodulate each audio signal of the same target frequency respectively to generate the corresponding soft information; use the digital selective calling diversity signal processing device to merge and then decode each soft information to obtain the message corresponding to the audio signal. This application monitors the audio signals of multiple frequencies through the wide-area cooperation of multiple multi-channel digital receiving devices, thereby realizing the full-frequency wide-area reception of "ship-shore" signals, and then merging each audio signal to improve the reception stability. Compared with the "point-to-point" short-wave time-varying channel, the "single-point-to-multipoint" quasi-constant parameter channel of this application can more stably and reliably realize short-wave communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 It is a schematic flowchart of a digital selective calling signal receiving method provided by an embodiment of the present application;

[0040] Figure 2 It is an example diagram of the working principle of the diversity reception scheme provided by an embodiment of the present application;

[0041] Figure 3 It is an example structure diagram of the DSC service diversity reception system provided by an embodiment of the present application;

[0042] Figure 4 It is an equipment connection diagram of the DSC service diversity reception system provided by an embodiment of the present application;

[0043] Figure 5 It is a working principle diagram of the DSC service diversity reception system provided by an embodiment of the present application;

[0044] Figure 6 It is an initialization flowchart of the DSC service diversity reception system provided by an embodiment of the present application;

[0045] Figure 7 It is a DSC signal diversity reception flowchart provided by an embodiment of the present application;

[0046] Figure 8It is an example diagram of the reception effect and link maintenance time of the diversity reception method provided by the embodiments of the present application;

[0047] Figure 9 It is an example diagram of the performance improvement effect of the diversity combining method on signal demodulation provided by the embodiments of the present application;

[0048] Figure 10 It is a schematic structural diagram of a digital selective call signal receiving device provided by the embodiments of the present application;

[0049] Figure 11 It is a schematic hardware structure diagram of an electronic device provided by the embodiments of the present application. Detailed implementation manners

[0050] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to 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. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are only examples of devices and methods that are consistent with some aspects of the embodiments of the present application detailed in the appended claims.

[0051] It can be understood that the terms "first", "second", etc. used in the present application can be used herein to describe various concepts, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of the present application, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information. Depending on the context, the words "if", "when" as used herein can be interpreted as "when...", "while...", or "in response to determining".

[0052] The terms "at least one", "a plurality", "each", "any one", etc. used in the present application, at least one includes one, two or more than two, a plurality includes two or more than two, each refers to each of the corresponding plurality, and any one refers to any one of the plurality.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0054] Refer to Figure 1The embodiment of the present application provides a method for receiving a digital selective calling signal. The method may include but is not limited to S100 to S130, as follows:

[0055] S100: monitoring audio signals of multiple target frequencies respectively through multiple multi-channel digital receiving devices.

[0056] As an optional implementation, the embodiment of the present application may further include the following steps:

[0057] Adjust the target frequencies monitored by the multi-channel digital receiving devices.

[0058] S110: When each of the multi-channel digital receiving devices receives the audio signal corresponding to any of the target frequencies, each of the multi-channel digital receiving devices is used to transmit the audio signal to a multi-channel digital selective call modulation and demodulation device.

[0059] S120: Utilize the multi-channel digital selective call modulation and demodulation device to demodulate the audio signals of the same target frequency respectively, thereby generating corresponding soft information.

[0060] S130: Utilize a digital selective call diversity signal processing device to combine and decode the soft information to obtain a message corresponding to the audio signal.

[0061] Furthermore, S130 may include the following steps S131-S132:

[0062] S131: Determine a weighting coefficient corresponding to each piece of soft information and then determine that a merging method of each piece of soft information is a maximum ratio merging method.

[0063] Furthermore, S131 may include the following steps:

[0064] The expressions for determining each of the audio signals are:

[0065] f i (t) = s i (t)+n i (t);

[0066] Among them, f i (t) represents the i-th audio signal at time t, s i (t) represents the target signal in the i-th audio signal at time t, n i (t) represents the noise signal in the i-th audio signal at time t;

[0067] Calculating target coefficients for each of the audio signals;

[0068] The expression of the target coefficient is as follows:

[0069]

[0070] Where k represents the target coefficient, and N is the total number of the audio signals;

[0071] Determine the weighting coefficients of each of the soft information according to the target coefficient;

[0072] The expression of the weighting coefficient is as follows:

[0073]

[0074] Where w i represents the weighting coefficient of the i-th soft information.

[0075] It can be understood that the obtained weighting coefficients in this embodiment may not be the same. For example, the lowest weighting coefficient is 0.1 and the highest weighting coefficient is 0.5. Furthermore, each audio signal can be weighted and combined according to the corresponding weighting coefficient, and the obtained combined audio signal can integrate the characteristics of each audio signal to obtain the maximum signal-to-noise ratio.

[0076] S132: Use the digital selective calling diversity signal processing device to perform weighted combination and then decoding on each of the soft information and the corresponding weighting coefficient to obtain the message corresponding to the audio signal.

[0077] Furthermore, the embodiment of the present application may further include the following steps:

[0078] Display the message through a display terminal; where the message includes the sending time of the audio signal, the call type of the audio signal, and the coordinates of the device sending the audio signal when sending the audio signal;

[0079] If the call type is a distress type, an audible and visual alarm is issued.

[0080] Next, the solution of the embodiment of the present application will be introduced and described in detail in combination with specific application examples.

[0081] To effectively overcome the inherent defects of shortwave communication such as time-varying and unstable, in recent years, with the improvement of signal processing technology and the performance level of components, shortwave diversity reception technology has gradually emerged and made great progress in various communication fields. The diversity reception technology can achieve wide-frequency wide-area reception of "ship-shore" signals through the wide-area cooperation of multiple receiving stations, transform the traditional shortwave time-varying channel of "point-to-point" into a quasi-constant parameter channel of "point-to-multipoint", and achieve stable and reliable shortwave communication.

[0082] First, the diversity reception solution of this embodiment will be described.

[0083] I. Working principle of diversity reception:

[0084] The medium- and long-distance transmission of shortwave signals mainly relies on ionospheric reflection. The basic parameters of the ionosphere, such as height, thickness, stratification, and electron density, are constantly changing irregularly under the influence of day and night, seasons, latitude, solar activity, etc. This inherent characteristic of the shortwave channel makes the traditional "point-to-point" communication mode always have defects such as unreliable communication links and low service transmission success rates. The diversity reception technology interconnects multiple receiving stations widely distributed in space through wires, and improves the received signal quality and channel stability by uniformly combining and processing the signals from each receiving station. Its basic working principle is as Figure 2 shown (taking the QPSK modulation method as an example for intuitive understanding).

[0085] The main differences between the traditional reception method and the diversity reception method are as follows:

[0086] Traditional reception method: Single-channel reception, demodulation, and decision-making, unable to correct decision errors caused by unstable transmission channels;

[0087] Diversity reception method: Multiple-channel parallel reception, demodulation, and weighted combination (weighted combination according to the signal-to-noise ratio, i.e., "maximum ratio combination") of the "soft information" (IQ data containing the phase characteristics of the original information) obtained after demodulation. After combination, decision-making is carried out, and the original information can be restored with a higher probability.

[0088] The technical characteristics of diversity reception are as follows:

[0089] 1. It can be effectively used for digital services: The diversity reception technology needs to combine and make decisions on the "soft information" after demodulation, so it can process digital services;

[0090] 2. The more cooperative receiving stations within 10, the better: The diversity reception technology performs weighted combination according to the received signal-to-noise ratio of each receiving channel. Therefore, the more cooperative stations, the higher the correct probability of diversity decision-making. However, due to the "diminishing marginal utility" principle, when there are enough receiving stations, the benefits obtained by adding more receiving stations are small. Considering the input-output ratio comprehensively, generally 3 - 5 receiving stations are appropriate;

[0091] 3. The distance between cooperative receiving stations should be much greater than the shortwave wavelength: Receiving stations with similar distances often have similar ionospheric characteristics, and their received signals cannot be regarded as independent uncorrelated signals. Therefore, the selected distance between receiving stations should be much greater than the shortwave wavelength (generally 100 times). Calculated based on the wavelength corresponding to a frequency of 2 MHz, the distance between receiving stations should be greater than 15 km appropriately.

[0092] Significance of diversity reception: Improve the reception efficiency of digital selective calling signals. The fragmented signals received by each station are processed through diversity reception to obtain complete signals, avoiding missing important search and rescue information and ensuring the safety of lives and property at sea.

[0093] III. System architecture: The DSC service diversity reception system applying the diversity reception scheme can be an important part of the GMDSS system. In this embodiment, relying on the existing IP transmission network (such as communication dedicated lines, etc.), the shortwave receiving stations widely distributed can be interconnected for communication, realizing the diversity reception and combining processing of the DSC signals sent by ships. The overall function is equivalent to providing an enhanced receiving channel for the GMDSS system, and its architecture is as Figure 3 shown.

[0094] IV. Equipment composition and configuration:

[0095] The DSC service diversity reception system mainly consists of a central control console, an IP transmission network, and multiple receiving stations. Based on the GMDSS application system, it can be constructed by adding some equipment and relevant service interface protocols. The equipment composition and connection relationship are as Figure 4 shown. Among them, multi-channel digital receiving equipment, a receiver local controller, and a switch are newly added to each receiving station. The multi-channel digital receiving equipment realizes the multi-channel parallel reception of shortwave DSC signals and the audio data transmission (carried on IP). The receiver local controller is used to configure the parameters of the multi-channel digital receiving equipment and monitor the equipment status; multi-channel DSC modulation and demodulation equipment, DSC diversity signal processing equipment, and a switch are newly added to the central control console. The multi-channel DSC modulation and demodulation equipment is used to demodulate the audio data from each receiving station and generate DSC signal "soft information"; the DSC diversity signal processing equipment is used to perform combined decision decoding on the multi-channel DSC "soft information". At the same time, an interface with the DSC diversity signal processing equipment needs to be added to the GMDSS application system to realize the reporting of service messages after DSC diversity reception.

[0096] V. Working process of this embodiment:

[0097] (I) Basic working principle.

[0098] The basic working principle of the DSC service diversity reception system is as Figure 5As shown in the figure. Each receiving station monitors multiple frequencies in parallel and sends the received audio signals to the multi-channel DSC modulation and demodulation equipment in the central control console (the preferred transmission method is IP transmission, and traditional audio line transmission is also supported); the multi-channel DSC modulation and demodulation equipment demodulates the audio of the same frequency from multiple receiving stations respectively, generates soft information and sends it to the DSC diversity signal processing equipment; the DSC diversity signal processing equipment weights and combines and decodes the multiple paths of soft information, restores the data and sends it to the GMDSS service system. From the above working process, it can be seen that: the overall working process is equivalent to an enhanced receiving channel, and the enhancement of the receiving channel only optimizes the physical layer and has no impact on the upper layer control logic and applications.

[0099] (2) System initialization process.

[0100] Before the DSC service diversity receiving system works, it needs to be initialized, that is, to establish the routing relationship of the diversity receiving data flow. The initialization process is as Figure 6 shown.

[0101] The detailed steps are as follows:

[0102] 1) Steps 1-4: Each receiving station manually sets the DSC monitoring frequency of a certain channel in the multi-channel digital receiving equipment. The multi-channel digital receiving equipment sends a registration request (including the receiving station ID, equipment ID, service type, DSC monitoring frequency, etc.) to the multi-channel DSC modulation and demodulation equipment, and the multi-channel DSC modulation and demodulation equipment returns the registration result;

[0103] 2) Steps 5-6: After the operator runs the monitoring terminal software and enters the user name and password, clicks to log in to the GMDSS application system. After the GMSSS application system authenticates the user name and password, it returns the login result. If the login is successful, after the operator selects parameters such as the service type and DSC monitoring frequency, the control terminal enters the DSC monitoring interface.

[0104] (3) DSC signal diversity receiving process.

[0105] The DSC signal diversity receiving process is as Figure 7 shown.

[0106] The detailed steps are as follows:

[0107] 1) Step 1: After the ship is in distress, edit the DSC message and send it on the specified frequency;

[0108] 2) Steps 2-5: Each receiving station sends the audio signal received on the fixed frequency to the multi-channel DSC modulation and demodulation equipment (supporting IP network / analog line transmission). It demodulates the DSC audio signal to generate "soft information", and reports it to the DSC diversity signal processing equipment for combined decoding processing;

[0109] 3) Steps 6 - 7: The DSC diversity signal processing device sends the combined and decoded message to the GMDSS application system. The GMDSS application system pushes the received DSC message to the pre - logged - in duty terminals (whose duty frequencies are the same as the reporting frequencies of the DSC messages), and the terminals perform interface display and audible - visual alarm output.

[0110] VI. Estimation of Wired Network Transmission Bandwidth Requirements.

[0111] The multi - channel digital receiving devices deployed at each receiving station send the audio signals received on the DSC standby frequencies to the multi - channel DSC modulation - demodulation devices at the console through the IP transmission network. The data transmission follows the PCM standard. The audio data payload is 153.6 kbps (16 - bit quantization, 9.6 kHz sampling rate). Considering a small amount of control commands and network encapsulation overheads, the wired network transmission bandwidth requirement for a single - channel frequency point is approximately 200 kbps.

[0112] For the receiving stations, if 12 DSC frequencies are parallely monitored, the total bandwidth requirement is 200 kbps × 12 = 2.4 Mbps.

[0113] For the console, each DSC frequency is diversity - received by n receiving stations. For example, if n = 2, the total bandwidth requirement is 2.4 Mbps × n = 4.8 Mbps; where n is a positive integer.

[0114] VII. Expected Goals:

[0115] In the diversity - receiving working mode, since the receiving stations participating in wide - area cooperative diversity are widely distributed in space and the distance between them is much greater than the short - wave wavelength, the independence between each receiving channel is relatively strong. The signal diversity reception and combination processing alleviate the problem of poor signal transmission quality caused by the time - varying and low - stability of a single channel. The overall effect is good. In some embodiments, the distance between each receiving station should be much greater than the short - wave wavelength (generally taking 100 times). Calculated by the wavelength corresponding to a 2 - MHz frequency, the distance between receiving stations should be greater than 15 km preferably.

[0116] Experimental measurements show that: after adopting the diversity - receiving technical solution of this embodiment, the success rate of network data transmission is significantly improved. The data transmission success rates of each short - wave station working alone are respectively between 23% and 76%. After adopting the diversity combination mechanism, the data transmission success rate can reach more than 99% (the sample size exceeds 630,000), fully demonstrating the superiority of this embodiment.

[0117] Analysis of the communication logs during the experiment shows that, in the "point-to-point" working mode of traditional shortwave communication, the passability of the shortwave link can generally only be maintained for a few minutes to more than a dozen minutes. After adopting the diversity reception technology, through the spatial diversity reception of signals, the passability of the "point-to-multipoint" shortwave link can be stably maintained for up to 6 hours, as Figure 8 shown. By comparison, it can be seen that the diversity reception technology solution of this embodiment transforms the fast fading time-varying channel in the "point-to-point" mode into a quasi-constant parameter channel in the "point-to-multipoint" mode, significantly improving the reliability and stability of shortwave communication.

[0118] According to the wide-area cooperative diversity reception technology special experiment of this embodiment, it can be known that: by introducing the diversity reception technology solution, the transformation of shortwave communication from "point-to-point" to "point-to-multipoint" is realized, alleviating the communication interruption phenomenon caused by the time-varying and unstable single channel, and significantly improving the pass rate and stability of shortwave communication.

[0119] More specifically, this embodiment details the steps of combining each audio signal based on the wide-area cooperative signal diversity information processing technology solution.

[0120] The wide-area cooperative signal diversity reception technology adopts the uplink full-frequency wide-area reception technology. This embodiment adopts the strategy of linearly combining uncorrelated multi-channel signals to resist deep fading. The combined signal generates a signal-to-noise ratio gain relative to the single-channel signal, and the demodulation signal-to-noise ratio is improved; the relative fading amplitude of the combined signal is reduced, obtaining a diversity gain. Reflected in the demodulation bit error rate - signal-to-noise ratio curve, the signal-to-noise ratio gain moves the curve as a whole to the left; the diversity gain makes the slope of the curve increase with the number of diversity channels, the bit error rate curve becomes steeper, and the bit error rate decreases more sharply with the increase of the signal-to-noise ratio, which greatly improves the bit error rate performance. The performance improvement of the diversity technology on signal demodulation is as Figure 9 shown. When the number of diversity channels approaches infinity, the channel approaches an AWGN channel with infinite signal-to-noise ratio.

[0121] In the shortwave diversity reception signal processing, the spatial diversity method of full-frequency wide-area reception is adopted. Since the shortwave stations participating in the wide-area cooperative signal diversity reception are widely distributed in space, the influence of the long shortwave wavelength and the similar ionospheric characteristics in the adjacent area is eliminated, and the independence between each receiving channel is relatively strong.

[0122] The key to signal diversity reception technology lies in selecting an appropriate diversity combining method. Diversity has two meanings: one is decentralized transmission; the other is centralized processing, that is, at the receiving end of the communication system, multiple independent uncorrelated or weakly correlated fading signals are combined to reduce the impact of fading. After receiving M diversity signals at the receiving end, a linear combiner is generally used to weight and combine the input M independent fading signals for output. Assuming the M input signals are r1(t), r2(t), ··· r M (t), the output of the combiner can be expressed as: where a k is the weighting coefficient of the k-th signal. In this embodiment, the weighting coefficient is selected to form the maximal ratio combining (MRC) method.

[0123] The specific scheme of the maximal ratio combining method is as follows:

[0124] In maximal ratio diversity combining, in order to make the proportions of signals in different signal-to-noise ratio branches different in the final total signal, unequal-weighted combining is adopted. When taking the weights, they must be weighted according to the ratio of the respective signal power to the noise power and then summed.

[0125] Let the received signals of each branch be:

[0126] f i (t) = s i (t) + n i (t);

[0127] where s i (t) and n i (t) are the signal and noise of the received signals of each branch at the receiving end. After weighted combining the signals of each branch with the weighting coefficient w i (t), we can get:

[0128]

[0129] where s0(t) and n0(t) are the signal and noise of the combined output respectively. Then the power of the output signal after diversity combining is:

[0130]

[0131] Since the branch noises are uncorrelated with each other, the output noise power is the sum of the input noise powers, which is:

[0132]

[0133] The signal-to-noise ratio of the combined output signal is:

[0134]

[0135] According to the Cauchy - Schwarz inequality, it can be obtained that:

[0136]

[0137] It can be obtained that:

[0138]

[0139] It can be seen that the maximum signal - to - noise ratio of the signal after maximum ratio diversity combining is the sum of the signal - to - noise ratios of each branch signal.

[0140]

[0141] From the above formula, it can be known that if the signal - to - noise ratio after combining is to reach the maximum value, the corresponding weighting coefficient of each branch should be:

[0142]

[0143] The reason why maximum ratio combining can obtain the maximum signal - to - noise ratio is that the branch with a large signal - to - noise ratio has a large weighting value, and the contribution of the signal of this branch to the output signal of the combiner is large. On the contrary, if the signal - to - noise ratio of the branch signal is small, the corresponding weighting value is also small, and its contribution to the combined output signal becomes small. If the signal - noise power of each branch signal is the same, the weighting coefficient only changes with the amplitude of the corresponding branch signal, and the maximum ratio diversity combining method can improve the signal - to - noise ratio of the received signal greatly.

[0144] Referring to Figure 10 , the embodiment of the present application also provides a digital selective call signal receiving device, which can implement the above - mentioned digital selective call signal receiving method. The device includes:

[0145] A signal monitoring unit, configured to monitor the audio signals of multiple target frequencies respectively through multiple multi - channel digital receiving devices;

[0146] A signal transmission unit, configured to, when each of the multi - channel digital receiving devices receives the audio signal corresponding to any of the target frequencies, use each of the multi - channel digital receiving devices to transmit the audio signal to a multi - channel digital selective call modulation and demodulation device;

[0147] A signal demodulation unit, configured to use the multi - channel digital selective call modulation and demodulation device to demodulate each of the audio signals of the same target frequency respectively to generate corresponding soft information;

[0148] A signal decoding unit, configured to use a digital selective call diversity signal processing device to combine and decode each of the soft information to obtain the message corresponding to the audio signal.

[0149] It can be understood that the content in the above method embodiments is applicable to the device embodiments of the present application. The functions specifically implemented by the device embodiments of the present application are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those of the above method embodiments.

[0150] An embodiment of the present application also provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the above-mentioned method for receiving a digital selective call signal. The electronic device can be any intelligent terminal including a tablet computer, a vehicle-mounted computer, etc.

[0151] It can be understood that the content in the above method embodiments is applicable to the device embodiments of the present application. The functions specifically implemented by the device embodiments of the present application are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those of the above method embodiments.

[0152] Please refer to Figure 11 , Figure 11 , which schematically shows the hardware structure of an electronic device in another embodiment. The electronic device includes:

[0153] A processor 1101, which can be implemented in ways such as a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided by the embodiments of the present application;

[0154] A memory 1102, which can be implemented in forms such as a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 1102 can store an operating system and other application programs. When implementing the technical solutions provided by the embodiments of this specification through software or firmware, the relevant program codes are stored in the memory 1102, and the processor 1101 is called to execute a method for receiving a digital selective call signal in an embodiment of the present application;

[0155] An input / output interface 1103, which is used to implement information input and output;

[0156] A communication interface 1104, which is used to implement communication interaction between this device and other devices. It can communicate through a wired method (such as USB, network cable, etc.) or through a wireless method (such as a mobile network, Wi-Fi, Bluetooth, etc.);

[0157] The bus 1105 transmits information among various components of the device (such as the processor 1101, the memory 1102, the input / output interface 1103, and the communication interface 1104);

[0158] Among them, the processor 1101, the memory 1102, the input / output interface 1103, and the communication interface 1104 achieve communication connections with each other inside the device through the bus 1105.

[0159] The embodiment of the present application also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the above-mentioned method for receiving a digital selective call signal.

[0160] It can be understood that the content in the above method embodiments is applicable to the embodiments of this storage medium. The functions specifically implemented by the embodiments of this storage medium are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those of the above method embodiments.

[0161] As a non-transitory computer-readable storage medium, the memory can be used to store non-transitory software programs and non-transitory computer-executable programs. In addition, the memory can include high-speed random access memory, and can also include non-transitory memory, such as at least one disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory may optionally include a memory remotely provided relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above networks include, but are not limited to, the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0162] The embodiments described in the embodiments of the present application are for more clearly illustrating the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. Those skilled in the art know that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of the present application are equally applicable to similar technical problems.

[0163] Those skilled in the art can understand that the technical solutions shown in the figures do not constitute a limitation on the embodiments of the present application, and may include more or fewer steps than those shown in the figures, or combine certain steps, or different steps.

[0164] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0165] Those of ordinary skill in the art will understand that all or some of the steps in the methods disclosed above, and the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or a suitable combination thereof.

[0166] As used in the specification of this application and the above-mentioned drawings, the terms "first", "second", "third", "fourth", etc. (if any) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of this application described here can be implemented in an order different from those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that comprises a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0167] It should be understood that in this application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects and indicates that there can be three relationships. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist at the same time. Here, A and B can be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. "At least one (one) of the following" or a similar expression means any combination of these items, including any combination of single items (ones) or plural items (ones). For example, at least one (one) of a, b, or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0168] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the above-mentioned unit division is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling, direct coupling, or communication connection to each other can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be in electrical, mechanical, or other forms.

[0169] The units described above as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed over multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0170] In addition, each functional unit in various embodiments of the present application may be integrated into a processing unit, may exist separately as individual physical units, or two or more units may be integrated into one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0171] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present application. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store programs.

[0172] The preferred embodiments of the embodiments of the present application have been described above with reference to the accompanying drawings. This does not limit the scope of the rights of the embodiments of the present application. Any modifications, equivalent replacements, and improvements made by those skilled in the art without departing from the scope and essence of the embodiments of the present application shall be within the scope of the rights of the embodiments of the present application.

Claims

1. A method for receiving a digital selective call signal, characterized in that, The method includes the following steps: Use multiple multi-channel digital receiving devices to respectively monitor the audio signals of multiple target frequencies; When each of the multi-channel digital receiving devices receives the audio signal corresponding to any of the target frequencies, use each of the multi-channel digital receiving devices to transmit the audio signal to a multi-channel digital selective calling modulation and demodulation device; Use the multi-channel digital selective calling modulation and demodulation device to demodulate each of the audio signals of the same target frequency to generate corresponding soft information; Use a digital selective calling diversity signal processing device to combine and then decode each of the soft information to obtain the message corresponding to the audio signal.

2. The digital selective call signal receiving method according to claim 1, characterized in that The step of using a digital selective calling diversity signal processing device to combine and then decode each of the soft information to obtain the message corresponding to the audio signal includes the following steps: Determine the weighting coefficients corresponding to each of the soft information and then determine the combination method of each of the soft information as the maximum ratio combination method; Use the digital selective calling diversity signal processing device to perform weighted combination and then decoding on each of the soft information and the corresponding weighting coefficients to obtain the message corresponding to the audio signal.

3. A method for receiving a digital selective call signal according to claim 2, characterized in that, The step of determining the weighting coefficients corresponding to each of the soft information and then determining the combination method of each of the soft information as the maximum ratio combination method includes the following steps: Determine the expressions of each of the audio signals as: f i (t) = s i (t) + n i (t); Among them, f i (t) represents the i-th said audio signal at time t, s i (t) represents the target signal in the i-th said audio signal at time t, n i (t) represents the noise signal in the i-th said audio signal at time t; Calculate the target coefficients of each of the audio signals; The expression of the target coefficient is: Where k represents the target coefficient and N is the total number of the audio signals; Determine the weighting coefficients of each of the soft information according to the target coefficients; The expression of the weighting coefficient is: Among them, w i represents the weighting coefficient of the i-th piece of the soft information.

4. A method for receiving a digital selective call signal according to claim 1, characterized in that, The method further includes the following steps: Display the message through a display terminal; wherein, the message includes the sending time of the audio signal, the call type of the audio signal, and the coordinates of the device sending the audio signal when sending the audio signal; If the call type is a distress type, then give an audible and visual alarm.

5. A digital selective call signal receiving method according to any one of claims 1 to 4, characterized in that, The method further includes the following steps: Adjust each of the target frequencies monitored by each of the multi-channel digital receiving devices.

6. A digital selective call signal receiving apparatus, characterized in that, The device includes: A signal monitoring unit for using multiple multi-channel digital receiving devices to respectively monitor the audio signals of multiple target frequencies; A signal transmission unit for, when each of the multi-channel digital receiving devices receives the audio signal corresponding to any of the target frequencies, using each of the multi-channel digital receiving devices to transmit the audio signal to a multi-channel digital selective calling modulation and demodulation device; A signal demodulation unit for using the multi-channel digital selective calling modulation and demodulation device to demodulate each of the audio signals of the same target frequency to generate corresponding soft information; A signal decoding unit for using a digital selective calling diversity signal processing device to combine and then decode each of the soft information to obtain the message corresponding to the audio signal.

7. An electronic device, characterized in that, The electronic device includes a memory and a processor, the memory stores a computer program, and when the processor executes the computer program, the method described in any one of claims 1 to 5 is implemented.

8. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, the method described in any one of claims 1 to 5 is implemented.

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