中英文翻译--校园自动锁相调频发射原理.doc

INTELL IGENT FREQUENCY MODULATI ON OF CAMPUS BROADCASTING SYSTEM FM radio is the way the FM audio signal transmission, the carrier wave frequency modulation with the audio signal changes center frequency in the carrier (not the center frequency modulation ago) on both sides of change, second change the offset frequency and audio signal the same modulation frequency, such as the frequency of audio signal 1KHz, the carrier frequency offset changes in the number of times per second 1K. The size of offset with the amplitude of audio signal size. FM transmitters in the domestic Specifications limit to allow the maximum frequency offset ± 75KHz, the frequency response 80-10000Hz (± 3dB), harmonic radiation-60dB (for a fundamental 0dB), the frequency stability of 1 × 10-6, letter noise ratio ≥ 50dB, total harmonic distortion ≤ 0.1%, transmitting frequency 87 - 108MHz, the general provisions of the school in the 70 - 87MHz between. Intelligent broadcasting system on campus as an innovative and practical equipment of modern education, in line with the countrys industry and the Ministry of Educations education-oriented information to and is widely considered an alternative school of traditional e-ring and ear-piercing loudspeakers broadcasting the green environment-friendly products. The system with the latest computer numerical control technology, high-fidelity audio technology, created the music (or music ring tones) instead of e-ring precedent. Broadcast system, which is indispensable for each school, one of the infrastructure, although in recent years video and network technology in the rapid development of the broadcasting system but still its practicality, economy, convenience was a variety of units, places of application . Existing types of schools in China are basically the public address system, it mainly used for various public occasions, such as all of public broadcasting, notification, broadcast a variety of literary and artistic programs, recognition of advanced