Where there is a campus radio design Luohe Henan Jiaming Yang 1503 +71780 +75 www.69139139.com 1399 +229 +631 Zheng * City Market Milan sun in our existing educational institutions in Unit 2, Building 208, Campus Public campus radio to reach widely used in all types of schools, mainly used for the flag-raising, the day-to-day school management of eye cao, notice, campus radio cao, Games. With the rapid development of information technology, digital multimedia equipment has been applied in teaching, especially in recent years, the school informatization construction was speeded up, computer, Internet, multimedia, and a number of high-tech applications to teaching the practice of traditional teaching methods fundamental change. Existing campus radio system this situation, obviously not with other modern educational technology system matching is far from meeting the needs of the development of modern education. The function of the school campus campus radio also put forward higher requirements, the the campus smart campus radio It is in such strong demand emerged. Campus smart campus radio manufacturers have been offering different features and technical level, the campus smart campus radio products, but the means of transmission can basically be divided into: constant pressure campus radio FM campus radio, the network campus radio three categories. The manufacturers of products and technical analysis in a large number of different levels to publicize their own the campus smart campus radio products from different angles, what programs should be used, but the construction of the the campus smart campus radio system, in the end, choose what kind of products and manufacturers? School terms like smoke and mirrors, it is difficult to distinguish a true state-of-the-art technology, stable performance campus the intelligent campus radio products. Following on campus the intelligent campus radio products according to their works and transmission mode parsing for schools in the the campus campus radio construction reference. A the smart campus radio technical background of constant pressure transmission mode analysis: constant pressure the campus radio oldest the public campus radio into the campus, its working principle is to direct amplification of the audio signal, based on the power signal transmission. 4 ~ 16Ω matched impedance transformation through a step-up transformer to 100V constant voltage transmission to the terminal after the buck converter to drive speaker 4 ~ 16Ω matched impedance, the general transmission distance is a few tens of meters to reduce line transmission loss to several hundred meters. Advantages: the technology is mature, simple structure, stable performance, easy maintenance, cheap terminal. Now widely used in railway stations, docks, schools, commercial and civil construction background music, and many manufacturers developed based on the linkage with the fire protection system, emergency campus radio. Disadvantages: ① poor sound quality, distortion and high: given the pressure transmitted by the line transformer bandwidth, speaker size, cable diameter factors, frequency response range of 200Hz ~ 12KHz, Distortion ≤ 10% can not be achieved stereo transmission. ② small program capacity, can not the addressable control: a line can only transfer a set of programs, in terms of the current school foreign language listening training requirements of multi-grade synchronization, the transmission of a program is not enough, unable to meet the campus radio and partition campus radio, campus radio not achieve point-to-point addressing. For example, the principals want the speech to a class or to speak to a few classes, campus radio constant pressure can not be done, only all speakers at the same time the campus radio the other classes, which affect the normal classes. Eye cao simply played classrooms, offices, the campus radio cao cao field you can simply play background music only dormitory, dining spots, campus radio constant pressure can not be achieved on a single point or random grouping class campus radio. ③ backward technology, simple functionality, scalability: audio basically analog sources using the deck, unable to play digital audio file format, can not be achieved automatically play, automatic control. The campus radio are constant pressure in accordance with the principle of power matching and impedance matching design, but the end of the system wiring installation, the power to expand the capacity is very limited, and the program capacity expansion. Also manufacturers to introduce smart play instrument can be achieved on the basis of constant pressure campus radio automatically campus radio, switch timing control amplifier. But its storage space is limited, the program size is too small, low 16KHz, 8-bit audio sampling frequency to broadcast the sound quality is poor. The general storage program capacity of 8, 16, 32, 64 minutes, with automatic timed playback and switching power amplifier power control function, can basically meet the requirements of the broadcast of the daily school ringtones and cao class, but not be able to meet the training and examination of Listening Teaching requirements. Jiaming Yang 1503 +71780 +75 www.69139139.com 1399 +229 +631 Milan sun, Zheng * City Market Building 5, Unit 2, 208