Current Electronics and Telecommunications(TRANSFERRED)

Abstract This design uses a simple single-chip AT98S52 as the main control module, the use of simple external circuit to drive 16 * 16 dot matrix LED display. The use of burner can be very convenient to achieve the microcontroller and PC and other peripheral storage device data transmission, and can use the software to facilitate the display content of the diverse changes, on the other hand dot matrix display widely used in hospitals, airports, banks And other public places, so that the release of information into the dynamic screen era, so the design has a strong practical application.

Abstract At the end of the 20th century, the rapid development of electronic technology in its promotion had effectively promoted the development of social productive forces and social information to improve the degree. People of modern life pay more attention to the concept of time as compared to before. It can be said that time and money to draw the equal sign. For those who are very strict and accurate to grasp the time or things, the time is not accurate will bring a lot of trouble so the digital tube for the display clock than the pointer clock showed a great advantage. Digital display time is simple and clear while the time accurate display to seconds. Whilst we mechanically dependent on the crystal oscillator, it may sometimes lead to errors. Digital clock is the use of digital circuits to achieve 'time', 'minutes', 'seconds' digital display of the time device. Digital clock accuracy, stability far more than the old mechanical clock. In this design, we use LED digital tube display, minutes, seconds and 24-hour chronograph according to the digital tube dynamic display principle to display with 12MHz crystal oscillator oscillation pulse, timer count. In this design, the circuit has the display time of its function and can achieve the adjustment of time. Digital clock is its small, low price, travel time, high precision, easy to use, more features, easy to integrate and the majority of consumer favorite to get a wide range of use.

Abstract Environmental noise monitoring is an important link in improving the quality of life and strengthening environmental protection. In the bustling neighborhoods and residential areas of major cities, large-scale of environmental noise pollution have erected the streets. The design is mainly based on MCS89C5 1 microcontroller, which is the core of the audio detection system design. Capacitive electret microphone work by the principle of the sensor, the sound signal converts into electrical signal output when the microphone receiving noise, and then through the hardware circuit: amplify the signal, filtering A / D conversion circuit and software program control to complete the sound frequency detection function. Detection of the sound frequency display through the LED digital display, this design of the audio detection system is low cost, portable, can display environment noise digitally and so on. This can be widely used in industrial and mining enterprises, institutions and schools that need to measure and control the environment noise.

Abstract The traditional tape voice recording and reproducing system has many limitations due to its large volume and inconvenient use in the use of electronic and information processing. This paper presents a compact, low-power digital voice storage and playback system will be able to replace it. The basic principle of digital voice storage and playback system is the digital control of voice recording and playback. Among them, the key technology is that in order to increase the voice storage time and improve the utilization of memory, the use of non-distortion compression algorithm to compress the voice signal and then stored in the playback and then decompression while the input voice signal Filtering to suppress noise and interference, thus ensuring the reliable quality of voice playback. The system uses three methods, namely data acquisition, straight sampling, sample sampling and self-similar incremental modulation to complete the storage and playback of voice signals 32.7s, 65.5s and 147.4s respectively. The front straight AGC controls the speech signal within the controllable range of the A / D converter to ensure that the voice signal is not distorted. Bandpass filter a reasonable range effectively, filters out-of-band noise and reduces aliasing distortion. Through the post-level compensation circuit on the output of the voice signal correction, playback voice clear. The system has the functions of automatic recording, manual recording, recording and playing time display and protection of voice signal after power failure.

Abstract Satellite communication refers to the use of artificial earth satellites as a relay station to forward radio waves, between two or more earth stations in the communication. Satellite communications since 1945 development so far, greatly accelerating the process of social information. The research and use of our satellites began in the early 1970s. Satellite communication applications include applications in data transmission services, applications in mobile communication systems, applications in video broadcast services, and applications in interactive services such as telephony. With the advancement of satellite communication technology and the improvement of satellite communication capability, the application of satellite communication is becoming more and more extensive, and the service level is getting higher and higher. In today's rapid development of terrestrial communications, satellite communications in the development of the market despite the great difficulties and risks, and even suffered major setbacks, but because of its irreplaceable characteristics of the decision it is still to develop and application. Therefore, from the overall and long term, the future development prospects of satellite communications is still bright and beautiful. China's satellite communications development goals: good management, make good use of existing satellite communications systems, and actively develop new business, new markets, new systems and adhere to independent construction.