CN106506029A - A U-segment digital wireless audio transmission system and its transmission method - Google Patents

Abstract

The present invention discloses a kind of u piece of digital wireless audio transmission system, which includes discharger and reception device, the discharger includes that analogue audio frequency input module, analog-digital converter, emission control processor, transmitting radio frequency chip and transmitting antenna, the reception device include reception antenna, receive radio frequency chip, receive control process device, digital to analog converter and analogue audio frequency output module.Invention additionally discloses a kind of wireless audio transmission method for realizing u piece of digital wireless audio transmission systems.The invention has the advantages that：There is provided a kind of by surrounding environment influence less, transmission range is farther, it is stronger to pass through barrier ability, capacity of resisting disturbance is higher, the wireless audio transmission system that audio quality is higher and its transmission method.

Description

A U-segment digital wireless audio transmission system and its transmission method

technical field

The invention relates to the field of wireless audio transmission, in particular to a u-segment digital wireless transmission system and a transmission method thereof.

Background technique

In recent years, with the rapid development of wireless technology, this technology has penetrated more and more into various fields of people's daily life. Coupled with the maturing of digital communication technology, chip miniaturization technology and circuit technology, people are becoming more and more The more keen on building some functional systems on the basis of wireless communication.

At present, in the field of wireless audio transmission, it is basically divided into three categories: AM, FM and digital transmission, and the first two are the processing of analog signals, which are easily disturbed during the transmission of audio signals, especially when there are For high-power equipment with poor electromagnetic compatibility, its interference can easily affect this type of traditional wireless audio transmission system, often causing problems such as crosstalk, broken sound, popping sound, etc., which reduces the signal-to-noise ratio of the signal and also makes the The sound quality of traditional wireless audio transmission is severely limited. Taking the wireless microphone as an example, the working principle of the analog wireless microphone is that the transmitting end aggravates the analog signal from the sound source and after companding, modulates it onto the wireless analog carrier signal for wireless transmission, and the receiving end receives the wireless signal. After demodulation and de-emphasis, after companding, the analog audio signal is output and sounded through the speaker. The signal acquisition and transmission process of the analog wireless microphone system are all analog signals, which are more susceptible to interference and cause signal distortion than digital signals. At the same time, the channel bandwidth of the analog wireless microphone system is relatively narrow, which will happen when multiple wireless microphones are used in the same space at the same time. Serious problems of adjacent channel interference and intermodulation interference.

With the wireless technology getting more attention in the field of audio transmission, such as Bluetooth, WiFi and 2.4G technology, etc. have also been developed rapidly. However, these technologies mostly use wireless signals of higher frequency bands. Compared with lower wireless signals (such as u-band), they have the problems of too short transmission distance and too weak ability of transmission signals to penetrate obstacles. These two problems are serious. Limit the range of use of the wireless audio transmission system. Furthermore, with the popularization of wireless technology, handheld 2.4G devices such as smart phones and tablet computers are widely used in the 2.4G frequency band, which makes the frequency band more and more crowded, and the surrounding environment used by the wireless audio transmission system is full of various signals. It is more likely to cause problems such as co-channel interference, adjacent channel interference, and intermodulation interference, which will affect the use effect of the entire wireless audio transmission system.

Therefore, it is necessary to provide a wireless audio transmission system and a transmission method thereof that are less affected by the surrounding environment, have a longer transmission distance, stronger ability to pass through obstacles, stronger anti-interference ability, and higher audio quality.

Contents of the invention

The purpose of the present invention is to solve the problems in the existing wireless transmission technology that the transmission distance is too short, the ability of the transmission signal to penetrate obstacles is too weak, the signal is easily distorted by the interference of the surrounding environment, and the anti-interference ability is weak. A wireless audio transmission system with less impact from the surrounding environment, longer transmission distance, stronger ability to pass through obstacles, stronger anti-interference ability, and higher audio quality.

Another object of the present invention is to provide a wireless audio transmission method.

In order to realize the above-mentioned purpose of the invention, the present invention adopts the following technical solutions:

A U-segment digital wireless audio transmission system, which includes: a transmitting device and a receiving device, the transmitting device includes an analog audio input module, an analog-to-digital converter, a transmitting control processor, a transmitting radio frequency chip and a transmitting antenna, the receiving device It includes a receiving antenna, a receiving radio frequency chip, a receiving control processor, a digital-to-analog converter, and an analog audio output module; the input end of the analog audio input module is connected to an audio output device for receiving an analog audio input signal, and the analog audio The output terminal of the input module is connected to the analog-to-digital converter; the analog-to-digital converter converts the collected analog audio input signal into a digital audio signal, and outputs it to the launch control processor through the I2S interface; the launch control processor Connect to the transmitting radio frequency chip through the SPI serial interface, send the digital audio signal to the transmitting radio frequency chip to modulate the carrier, the transmitting radio frequency chip is connected to the transmitting antenna to form a signal link, and the The transmitting antenna transmits to the receiving device.

The transmitting radio frequency chip modulating the carrier wave of the digital audio signal is specifically: the transmitting radio frequency chip digitally modulates the digital audio signal by the RF radio frequency chip, and the transmitting radio frequency chip converts the digital audio signal from the transmitting control processor The signal is modulated into a u-segment digital radio frequency signal, and the u-segment digital radio frequency signal is a 400MHz-1GHz frequency band signal. The audio output device is a microphone, mobile phone, MP3 or other audio output devices; the transmitting control processor and the receiving control processor adopt MCU micro control unit.

In the receiving device, the receiving antenna receives the digital radio frequency signal transmitted by the transmitting device, and the receiving antenna outputs to the receiving radio frequency chip, and the digital radio frequency signal is a u-segment digital radio frequency signal. The receiving radio frequency chip uses the RF radio frequency chip to demodulate the digital radio frequency signal to obtain a digital audio signal, and the receiving radio frequency chip is connected to the receiving control processor through the SPI serial interface. The receiving control processor sends the digital audio signal to the digital-to-analog converter through the I2S audio interface, and the digital-to-analog converter converts the digital audio signal into an analog audio signal and outputs it to the analog audio output module, and the analog audio output module finally outputs the audio to complete The transmission process of wireless audio. In addition, the analog audio output module can be used as the last module of the receiving device, such as power amplifier, sound box, multimedia console, earphone, etc.

A kind of wireless audio transmission method, realizes the transmission process of above-mentioned U-segment digital wireless audio transmission system, it comprises the following steps:

Step 1: The analog audio input module receives an analog audio signal;

Step 2: converting the received analog audio signal into a digital audio signal;

Step 3: modulating the digital audio signal into a u-segment wireless audio signal;

Step 4: Transmit the u-segment wireless audio signal through the transmitting antenna;

Step 5: The receiving device receives the u-segment wireless audio signal;

Step 6: Demodulate the u-segment wireless audio signal into a digital audio signal;

Step 7: Convert the digital audio signal to an analog audio signal and output it externally.

The u-segment wireless audio signal is a 400MHz-1GHz frequency band signal.

Compared with prior art, the beneficial effect of the present invention is:

1. In this system, the analog audio is converted into digital audio through the analog-to-digital converter, and the digital transmission of the audio signal can be implemented. Due to its strong anti-interference ability and easy storage, processing and exchange, digital transmission system has become the most important transmission technology in modern communication network, and is widely used in various communication and transmission systems of modern communication network. In the digital signal transmission system, the analog signal sent by the source is encoded into a digital signal by the source of the digital terminal, and the digital signal sent by the terminal is converted into a digital signal suitable for channel transmission through channel coding, and then the signal is modulated by the modulator It is sent to the digital channel used by the system, then transmitted to the opposite end, and finally transmitted to the destination after reverse transformation.

The digital signal transmission system has the following advantages:

(1) Strong anti-interference ability, no noise accumulation. Digital audio is to preserve the sound by converting the sound wave waveform into a series of continuous binary data. Then for digital communication, the object of transmission is mainly analog voice signal, etc., and the channel is generally a binary digital signal. Since the amplitude of the digital signal is a limited discrete value (usually two amplitudes), in the transmission When the signal-to-noise ratio has not deteriorated to a certain extent, that is, at an appropriate distance, the regeneration method is used to regenerate the original transmission signal without noise interference, so long-distance high-quality transmission can be realized.

(2) It is convenient for encryption processing. The security and confidentiality of information transmission are becoming more and more important, and the encryption processing of digital communication is much easier than analog communication. Taking the voice signal as an example, the digitally converted signal can be encrypted and decrypted by simple digital logic operations.

(3) Easy to store, handle and exchange. The signal form of digital communication is consistent with the signal used by the computer, which is binary code, so it is convenient to be connected to the computer network, and it is also convenient to use the computer to store, process and exchange the digital signal, which can make the management and maintenance of the communication network automatic and intelligent.

(4) The equipment is easy to integrate and miniaturize. Digital communication uses time-division multiplexing and does not require bulky filters. Most of the circuits in the equipment are digital circuits, which can be realized by large-scale and ultra-large-scale integrated circuits, so they are small in size and low in power consumption.

(5) Occupying a wide channel frequency band. The frequency band of one analog telephone is 4kHz bandwidth, and one digital telephone occupies about 64kHz.

2. The system modulates the audio signal into a u-segment (400MHz-1GHz) signal through the radio frequency chip. The following formula is the loss calculation formula of the wireless signal when it is transmitted in the air:

Los＝32.44+20lg d(Km)+20lg f(MHz)

Los is the transmission loss, the unit is Db; d is the distance, the unit is Km; f is the working frequency, the unit is MHz. It can be seen that the transmission loss is proportional to the frequency. That is, the higher the frequency, the greater the transmission loss. In other words, in the case of the same transmission loss, the transmission distance is inversely proportional to the frequency. That is, the higher the frequency, the shorter the transmission distance.

At present, most 2.4G devices have short signal transmission distances, large attenuation during transmission, weak signal penetration and diffraction capabilities, and signals are easily blocked by objects. Relatively speaking, the u-segment (400MHz-1GHz) signal has a relatively low frequency, a long wavelength, strong penetrating ability, small signal loss and attenuation, and a long transmission distance. In terms of applications, since the 2.4GHz frequency band is an open frequency band without a license both internationally and domestically, many applications have been developed in this frequency band, and this frequency band is already very crowded. At present, the applications developed in the 2.4GHz frequency band mainly include: wireless local area network, Bluetooth, ZigBee wireless sensor network, some cordless phones, and other short-distance wireless communication devices, etc. Among them, wireless local area network and Bluetooth have been widely used, and wireless sensor network is also in the ascendant. However, because the u-segment (400MHz-1GHz) signal is not in the same segment as most of the frequency waves in daily life, the chance of being interfered is greatly reduced, and the u-segment is wide, so more frequency points can be divided to achieve the same occasion. Multiple frequency points without interference.

In this system, u-segment digital wireless audio transmission can be realized. In the wireless signal transmission part, the transmission frequency can be flexibly adjusted according to the actual situation, which not only overcomes the problem that the analog signal is easily interfered in the analog wireless audio transmission system, and the transmission channel bandwidth is relatively narrow. , and overcome the problem of short wireless transmission distances such as WiFi and Bluetooth in the 2.4G frequency band.

Description of drawings

Fig. 1 is a block diagram of the transmitting device in the present invention.

Fig. 2 is a block diagram of the receiving device in the present invention.

FIG. 3 is a flow chart of the wireless audio transmission method in the system invention.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Referring to FIG. 1 and FIG. 2, the u-segment digital wireless audio transmission system of the present invention includes a transmitting device and a receiving device.

1. Launching device

Figure 1 is a transmitting device, which includes an audio input module, an analog-to-digital converter (AD), a transmitting control processor, and a transmitting radio frequency chip. The analog audio input of the transmitting device is linked to the analog-to-digital converter, the analog-to-digital converter is connected to the transmitting control processor through the I2S interface, the transmitting control processor is connected to the transmitting radio frequency chip through the SPI interface, and the transmitting radio frequency chip is connected to the transmitting antenna to form a signal link. All components on the signal chain work under the control of the transmit control processor.

(1) Selection of audio input module:

The audio input module (Audio in) as the first module of the transmitter can be used to connect with audio output devices such as microphones, mobile phones, MP3, etc., and serve as the analog audio input of the entire wireless system.

(2) Analog-to-digital converter

An analog-to-digital converter is an A/D converter, and a common analog-to-digital converter converts an input voltage signal into an output digital signal. The function of A/D conversion is to convert the time-continuous and amplitude-continuous analog quantity into a time-discrete and amplitude-discrete digital signal. Therefore, A/D conversion generally needs to go through sampling, holding, quantization and encoding. step. In this system, the analog signal collected by the wireless microphone is converted into an electrical signal, which is amplified and sent to the AD converter to be converted into a digital quantity.

(3) Adoption of MCU launch control processor

The MCU micro-control unit is a single-chip microcomputer or single-chip microcomputer, which appropriately reduces the frequency and specifications of the central processing unit, and integrates peripheral interfaces such as memory, counters, and PLCs on a single chip to form a chip-level computer. Application occasions do different combination control. In this system, the MCU transmit control processor controls the analog-to-digital converter and radio frequency chip through the I2S and SPI interfaces, and can use the CRC coding method to control the errors generated in the transmission in the entire digital communication, and can perform FEC forward error correction . In the FEC mode, the receiving end can not only find the error, but also determine the error position of the binary symbol, so as to correct it, so as to improve the accuracy of digital message transmission. When there is no error control, the digital sequence output by the source will be directly sent to the channel, and the output of the channel will have errors due to interference in the channel.

(4) Launch RF chip

In some wired channels, if the transmission distance is not too far and the communication capacity is not too large, the digital baseband signal can be transmitted directly. In this system, the analog audio signal collected by the microphone is converted into a digital baseband signal by analog to digital. The RF radio frequency chip performs digital modulation on the digital baseband signal, and then sends the modulated signal to the channel for transmission, so as to realize the transmission of more bit information in a unit channel.

In the entire transmitting device, as shown in Figure 1, the audio signal in the figure is collected by a wireless microphone, converted by an analog-to-digital converter, and converted into a digital audio signal, which is sent to the transmission control processor through the I2S audio interface. The radio frequency chip is controlled by the transmission control processor through the SPI serial peripheral interface, and the audio is sent to the radio frequency chip to modulate the carrier wave, which is transmitted to the receiving device by the antenna. In the device, the transmitting control processor controls the radio frequency chip, and the transmitting radio frequency chip modulates the digital audio signal from the transmitting control processor into a signal of u segment (400MHz-1GHz).

2. Receiving device

Fig. 2 is a receiving device, which includes a receiving antenna, a receiving radio frequency chip, a receiving control processor, a digital-to-analog converter, and an analog audio output module. The receiving antenna of the receiving device is connected to the receiving radio frequency chip, the receiving radio frequency chip is connected to the receiving control processor through the SPI interface, and the receiving control processor is connected to the digital-to-analog converter through the I2S interface to form a signal link. All components on the signal chain work under the control of the receiving control processor.

(1) Receive RF chip

Digital demodulation is a method of encoding and transmitting information for the convenience of transmission. During the transmission process, the voice call will be converted into a series of digital signals, which will be converted into computer binary codes 0 and 1, and then decoded and restored to the original at the information receiving place. voice status. In the receiving device of this system, the digital radio frequency signal is demodulated by the RF radio frequency chip, that is, the inverse process of digital modulation, and then the demodulated signal is sent to the channel for transmission.

(2) MCU receiving control processor

In this system, the MCU receiving control processor controls the analog-to-digital converter and radio frequency chip through the I2S and SPI interfaces, and can use the CRC coding method to control the errors generated in the transmission in the entire digital communication, and can perform FEC forward error correction . In the FEC mode, the receiving end can not only find the error, but also determine the error position of the binary symbol, so as to correct it, so as to improve the accuracy of digital message transmission. When there is no error control, the digital sequence output by the source will be directly sent to the channel, and the output of the channel will have errors due to interference in the channel.

(3) Digital-to-analog converter

A digital-to-analog converter is a D/A converter. A digital-to-analog converter is a converter that converts a discrete signal in the form of a binary digital quantity into an analog quantity based on a standard quantity. In this system, the digital radio frequency signal received by the receiving antenna and transmitted by the transmitting module is converted into an analog audio signal by a D/A digital-to-analog converter.

(4) Selection of audio output module:

The audio output module (Audio out) can be used as the last module of the receiving device for power amplifiers, speakers, multimedia consoles, earphones, etc.

In the entire receiving device, firstly, the receiving radio frequency chip sends the received radio frequency signal to the receiving control processor through the SPI serial peripheral interface, and then sends the audio signal to the digital-to-analog converter through the I2S audio interface, and the digital-to-analog converter Convert the digital audio signal to an analog signal, and finally output the audio through the audio output module.

The following describes the working process of the u-segment digital wireless transmission system with reference to the preferred implementation mode of the present invention. When working, the launch control processor first controls the initialization before the launch device starts to work. During the initialization process, the launch control processor controls and determines that the transmit radio frequency chip is to modulate the digital audio signal into a U-segment (400MHz-1GHz) signal. Because compared with wireless signals such as 2.4G, u-segment wireless signals have the advantages of longer transmission distance and better anti-interference ability. After starting to work, the audio input module inputs the analog audio signal into the analog-to-digital converter and converts it into a digital audio signal. The digital audio signal is sent to the launch control processor through the I2S audio interface, and the launch control processor passes the SPI serial peripheral The interface controls the radio frequency chip, and sends the audio to the radio frequency chip to modulate the carrier wave. After modulation, it is transmitted from the antenna to the receiving device.

The receiving control processor controls the system initialization before the receiving device starts to work. During the initialization process, the receiving control processor controls and determines that the receiving radio frequency chip demodulates the u-segment (400MHz-1GHz) wireless signal into a digital audio signal. When starting to work, in the receiving device, the radio frequency chip first sends the received u-segment (400MHz-1GHz) wireless signal to the receiving control processor through the SPI serial peripheral interface, and after demodulation processing, a digital audio signal is obtained, and then The digital audio signal is sent to the digital-to-analog converter through the I2S audio interface, and the digital-to-analog converter converts the digital audio signal into an analog audio signal for external output, and finally outputs the audio to complete the wireless audio transmission process.

As shown in Figure 3, the wireless audio transmission system of the present invention comprises the following steps:

Step 1: The audio input module receives an analog audio signal;

Step 2: converting the received analog audio signal into a digital audio signal;

Step 3: Modulating the digital audio signal into a u-segment (400MHz-1GHz) wireless audio signal;

Step 4: Transmit the u-segment (400MHz-1GHz) wireless audio signal from the antenna;

Step 5: The receiving device receives the u-segment (400MHz-1GHz) wireless audio signal;

Step 6: Demodulate the u-segment (400MHz-1GHz) wireless audio signal into a digital audio signal;

Step 7: Convert the digital audio signal to an analog audio signal and output it externally.

The U-segment digital wireless audio transmission system and its transmission method provided by the present invention have been introduced in detail above. In this paper, specific examples have been used to illustrate the principle and implementation of the present invention. The descriptions of the above embodiments are only used to help understanding The method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and scope of application. In summary, the content of this specification should not be construed as a limitation of the invention.

Claims (9)

1. a kind of u piece of digital wireless audio transmission system, it is characterised in that:The system includes discharger and reception device, The discharger includes analogue audio frequency input module, analog-digital converter, emission control processor, transmitting radio frequency chip and transmitting Antenna, the reception device include reception antenna, receive radio frequency chip, receive control process device, digital to analog converter and simulation Dio Output Modules；The input of the analogue audio frequency input module is connected with audio output apparatus, for receiving analogue audio frequency Input signal, the outfan of the analogue audio frequency input module are connected to analog-digital converter；The analog-digital converter will be collected Analogue audio frequency input signal be converted to digital audio and video signals, exported to the emission control processor by I2S interfaces；Described Emission control processor is connected to the transmitting radio frequency chip by SPI serial line interfaces, and the digital audio and video signals are delivered to institute State transmitting radio frequency chip and be modulated carrier wave, the transmitting radio frequency chip is connected to the transmitting antenna, forms signal link, by The transmitting antenna is launched to the reception device.

2. a kind of u piece of digital wireless audio transmission system according to claim 1, it is characterised in that:The transmitting radio frequency Chip is modulated carrier wave to the digital audio and video signals and is specially：The transmitting radio frequency chip is by RF radio frequency chip logarithm word tones Frequency signal carries out digital modulation, and the digital audio and video signals from the emission control processor are modulated by the transmitting radio frequency chip For u piece of digital radiofrequency signals.

3. a kind of u piece of digital wireless audio transmission system according to claim 3, it is characterised in that:The u piece of digital is penetrated Frequency signal is 400MHz-1GHz frequency band signals.

4. a kind of u piece of digital wireless audio transmission system according to claim 1, it is characterised in that:The audio output Equipment is mike, mobile phone, MP3 or other audio output apparatus.

5. a kind of u piece of digital wireless audio transmission system according to claim 1, it is characterised in that:The emission control Processor and reception control process device adopt MCU micro-control units.

6. a kind of u piece of digital wireless audio transmission system according to claim 1, it is characterised in that:Dress is received described In putting, the digital radio signal that receives discharger transmitting by the reception antenna, the reception antenna are exported to described Receive radio frequency chip；The reception radio frequency chip is demodulated process by RF radio frequency chips to digital radio signal, obtains numeral Audio signal, the reception radio frequency chip are delivered to the reception control process device by SPI serial line interfaces.

7. a kind of u piece of digital wireless audio transmission system according to claim 6, it is characterised in that:Described reception controls Digital audio and video signals are delivered to digital to analog converter by I2S audio interface by processor, and digital audio and video signals are turned by digital to analog converter It is changed to simulated audio signal and exports to analogue audio frequency output module, analogue audio frequency output module finally exports audio frequency and completes wirelessly The transmitting procedure of audio frequency.

8. a kind of u piece of digital wireless audio transmission system according to claim 7, it is characterised in that:The analogue audio frequency Last module of output module as the reception device, can use power amplifier, audio amplifier, multimedia console, earphone or Other dio Output Modules.

9. a kind of wireless audio frequency transmission function side of the u piece of digital wireless audio transmission systems that realizes described in any one of claim 1-8 Method, comprises the following steps：

Step 1：Analogue audio frequency input module receives simulated audio signal；

Step 2：The simulated audio signal for being received is converted to digital audio and video signals；

Step 3：Digital audio and video signals are modulated to u section wireless audio signals；

Step 4：U section wireless audio signals are launched by transmitting antenna；

Step 5：Reception device receives u section wireless audio signals；

Step 6：U section wireless audio signals are demodulated into digital audio and video signals；

Step 7：Digital audio and video signals are converted to simulated audio signal and are externally exported.