Bluetooth anti-electromagnetic interference performance

Test and Analysis of Anti-electromagnetic Interference Performance of Bluetooth Technology

The common frequency band of Bluetooth technology in the world is 2.4GHz. Due to the strong openness of its frequency band range, it is inevitable to be subject to external electromagnetic interference during use, which affects the stability and security of data transmission. It is conducive to the wide application of bluetooth technology. Therefore, it is of great significance to explore the anti-electromagnetic interference performance of bluetooth technology and propose improvement countermeasures.

1. Overview of Bluetooth technology

Bluetooth is a radio technology suitable for short-range communication between devices, enabling real-time transmission and sharing of data. For example, the application of Bluetooth technology in mobile phones, PDAs, wireless headsets, notebook computers and emerging wearable devices can realize real-time transmission and sharing of information. Through the full use of Bluetooth technology, the speed of data transmission can be effectively improved, the communication process between mobile devices can be simplified, and a good foundation has been laid for the research of wireless communication. Bluetooth adopts distributed network structure and frequency hopping spread spectrum technology, supports point-to-point and point-to-multipoint communication, and its data rate can reach 24Mbit/s. At the same time, Bluetooth technology adopts a time-division duplex transmission scheme, which can fully realize full-duplex transmission, and has higher advantages compared with traditional data transmission methods.

1.1 Bluetooth technical characteristics

Bluetooth technology is a wireless communication technology integrating low power consumption, short-distance data transmission and openness. It is jointly released by Intel Ericsson, Nokia, Toshiba and International Business Machines Corporation. On the basis of making full use of short-distance and low-cost wireless transmission technology, Bluetooth technology establishes a complete short-range wireless connection station between fixed equipment and wireless communication equipment, which can realize real-time data transmission within a specific range. In fact, Bluetooth technology is to realize the effective control of software by establishing radio and radio air interface, that is to say, Bluetooth technology is an organic combination of computer technology and communication technology. The technical characteristics of Bluetooth mainly include the following points: 1) low power consumption; 2) low cost; 3) short distance; 4) high security: 5) real-time performance; 6) high-speed frequency hopping. Bluetooth technology can link various mobile devices, fixed communication devices, computers and other wearable devices in a network at the lowest cost within a short distance to form a peripheral interface for data transmission.

1.2 Main features of Bluetooth technology

First, Bluetooth technology uses the open ISM frequency band in the industrial, medical and scientific fields. The working range is 2.4GHz~2.4835GHz. for convenience. Second, Bluetooth technology can realize short-distance data transmission, and its working distance generally does not exceed 10m, and the maximum can be increased to 100m. By expanding the working range of Bluetooth, on the basis of ensuring the data transmission rate, effective immunity to electromagnetic interference can be realized, which has high security. Third, by increasing the application of frequency hopping and spread spectrum technology, Bluetooth technology usually divides 79 frequency points in the 2.4GHz~2.4835GHz frequency band, adopts a fast hopping rate, and the speed of data transmission is significantly improved compared with before. Anti-interference performance is also higher. Fourth, Bluetooth technology adopts time-division multiplexing multiple access technology: the data is packaged into data packets and transmitted in units of time slots. In this way, the problems of "collision" and "hidden terminals" in wireless communication are solved.

2. Anti-electromagnetic interference type of Bluetooth technology

The types of electromagnetic interference in Bluetooth technology mainly include two types: suppressing electromagnetic interference and avoiding electromagnetic interference. Avoiding electromagnetic interference refers to effectively avoiding electromagnetic interference by reducing the transmission signal level between each unit, while suppressing electromagnetic interference requires spread spectrum technology and recoding. For example, when the power is greater than 50dB and the environment is different, in order to ensure the rate of Bluetooth technology up to 24Mb/s, it is difficult to achieve only relying on coding technology, because electromagnetic signals are easier to interfere in a lower power environment, so the power should be selected sent in higher cases. If the time avoidance method is adopted, once strong electromagnetic interference occurs, the data transmission will be interrupted. At the same time, because some wireless communication devices are greatly affected by the bandwidth, between 2.4GHz and 2.4835GHz, the frequency of wireless communication devices With a bandwidth of 80MHZ, it is possible to find a frequency spectrum without electromagnetic interference, and use a filter to filter it to achieve effective suppression of electromagnetic interference. Accordingly, it is considered that the application of the frequency domain interference avoidance method in the Bluetooth technology data transmission process is strengthened, and the security of data transmission is higher.

3. Anti-electromagnetic interference performance test and analysis of Bluetooth technology

Realizing short-distance wireless transmission of data is the fundamental goal of Bluetooth technology application. At this stage, Bluetooth technology has been widely used in short-range communication with its advantages of high transmission speed and simplicity and convenience, and has a good application prospect in the field of home and office. But at this stage, the data transmission stability of Bluetooth technology needs to be further improved, and the anti-noise and electromagnetic interference performance needs to be improved. In this study, microwave ovens commonly used in households are selected as the research object, and its working range is 2.4GHZ. The factors affecting the anti-interference performance of Bluetooth communication technology are explored, and the report is as follows.

3.1 Bluetooth anti-jamming experimental instruments and equipment

In this study, the microwave oven is used as the main interference source, and the operating frequency of the microwave oven is 2450MHZ. The stopwatch is used as a time measurement tool, and the size of the transfer file is mainly 100K and 18O0K.

3.2 Experimental Principle of Bluetooth Anti-jamming

In this study, two test files with different sizes are selected, namely 1800K and 1OOK. During the experiment, the distance between the Bluetooth transceiver is set as dl, and the distance between the interference source and the Bluetooth transceiver is d2. Research the data transmission rate under the condition of different distances between the interference source and the Bluetooth open system. In the process of testing the influence of interference sources on voice transmission, the voice distortion is mainly tested by the senses.

3.3 Bluetooth anti-jamming experimental results

Through in-depth analysis of the results of this study, we can see that the design of the Bluetooth communication system is more scientific and reasonable. In the process of transmitting small files, the influence of interference sources on file transmission is almost non-existent. In the process of transmitting large documents, the Bluetooth system only has a slight impact on the transmission speed and time when the distance from the interference source is the closest. Tests of speech transmission under normal conditions under various conditions showed no speech distortion.

At the same time, after this test analysis, it can also be known that the interference source selected in this research-the microwave oven has a small transmission power, which is also the main reason why the noise interference has no obvious impact on the transmission time and rate of the Bluetooth system. It proves that the application of the Bluetooth system in the family has high feasibility, and its anti-jamming performance is enough to meet the family's demand for Bluetooth anti-jamming performance. However, in the process of applying the Bluetooth system in the industrial, medical and scientific fields, the transmission power of the interference source is much higher than that of the induction cooker, which poses a huge challenge to the anti-interference ability of the Bluetooth system. Therefore, in order to achieve high-quality communication, it is necessary to further improve the anti-electromagnetic interference performance of the Bluetooth system.

4. Effective countermeasures to improve the anti-electromagnetic interference performance of Bluetooth technology

4.1 Analysis of the interference problem in the Bluetooth working frequency band

The electromagnetic interference problem of the Bluetooth system operating in the 2.4GHZT frequency band mainly has the following two points: First, it comes from the electromagnetic interference inside the Bluetooth system. In the process of designing the internal circuit and interface of Bluetooth, if there is an unreasonable design phenomenon, it will cause the high-frequency electromagnetic radiation inside the Bluetooth system to radiate outwards, which will reduce the stability of the internal circuit of the Bluetooth system and is not conducive to improving the transmission of the Bluetooth system. speed. Second, electromagnetic interference from existing services. At this stage, although the communication between high-frequency Bluetooth devices generally relies on frequency hopping and direct sequence spread spectrum, and its transmission power is also within the range allowed by the country, it is affected by the antenna form, system structure and gain index of the Bluetooth system. Modulation schemes, frequencies, and guard bands of communication equipment all have significant differences. In addition, the 2.4GI-IZ frequency band has strong openness, and the use of the frequency band is more complicated, which increases the source of electromagnetic interference.

4.2 Bluetooth anti-jamming solution

First, for the internal interference of the Bluetooth system, designers should pay attention to improving the rationality of the circuit design of the Bluetooth system in the process of improving the Bluetooth system, so as to minimize the electromagnetic interference. Second, in view of the electromagnetic interference from the existing business, the designers need to focus on the research on the electromagnetic interference between the unified frequency Bluetooth system on the basis of arranging the radio frequency command for the wireless business, and rely on the frequency hopping technology to realize the anti-electromagnetic interference effective resistance. For example, a designer has strengthened the application of adaptive frequency hopping technology in the Bluetooth system in response to the problem of electromagnetic interference, enabling the Bluetooth system to automatically adjust its own frequency range in different situations to achieve effective avoidance of current electromagnetic interference , improve the pertinence of frequency hopping, and achieve effective resistance to electromagnetic interference. Through the application of adaptive frequency hopping technology, the environmental applicability of the Bluetooth system can be fully improved, and on the basis of ensuring data transmission time and rate, it can effectively resist electromagnetic interference and has high application value. In summary, through the test and analysis of the anti-electromagnetic interference performance of Bluetooth technology, it is found that the transmission power of the interference source, the internal interference of the Bluetooth system, and the existing services will have a certain impact on the anti-interference ability of the Bluetooth system.

Summarize

Through research, it is found that the transmission power of the interference source is an important factor affecting the transmission speed of Bluetooth technology. Therefore, in order to fully improve the anti-interference performance of Bluetooth technology, the internal and external circuit design of the Bluetooth system should be continuously improved, the application of adaptive frequency hopping technology should be increased, and the anti-electromagnetic interference ability of the Bluetooth system should be comprehensively improved.

The above are the details of the test and analysis of Bluetooth anti-electromagnetic interference performance introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.