CD by radio-digital radio broadcasting

Engineers have been looking at ways of broadcasting a digital radio service to the general public, which would ideally have the following features: sound quality comparable with that of the CD; reliable reception to all listeners in the coverage area; capability of offering coverage of all listeners; capability of fixed, mobile and portable reception using simple low grains antennas; simple push-button programme selection-no tuning; frequency efficiency, so that many services can be provided in any spectrum available; and capability of operation from terrestrial transmitters and/or satellite. The author describes the requirements of a digital audio broadcasting system regarding intersymbol interference and then discusses COFDM, coded-orthogonal frequency division multiplex. The author also discusses low-bit-rate sound, terrestrial transmission, satellite broadcasting, receivers, frequency allocation and system testing     

基于LPC2138的AES3数字音频接口设计

随着数字音频技术的不断发展,数字化音频设备已广泛应用于广播电视节目领域。鉴于专业数字音频设备越来越多地需求,以及专用接收发送设备的复杂性,本设计采用Philips公司的ARM7控制芯片LPC2138结合音响设备专用芯片,设计一个简单的AES/EBU(AES3)数字音频收发系统,实现了专业AES3数字音频的接收与发送。实验显示,在输入1 kHz,24 dBu时,本设计的总谐波失真小于0.005%,信噪比大于90 dBu。     

Digital audio broadcasting: High-grade service quality through on-board processing techniques

A digital audio broadcasting (DAB) satellite system is presented here which provides a high-grade quality of service for some hundreds of channels. This, with minimum cost of the radio set and of the broadcasting station, greatly improves the radio broadcasting service throughout the world, especially in areas where deployment of conventional relay infrastructure is difficult and not yet cost-effective. Potential broadcasters located in the visible hemisphere can directly up-link their programming to the DAB satellites. Broadcasters can also copy each up-link channel and steer flexibility to any beam or combination of satellite beams. The paper illustrates the advantages and the feasibility of a DAB system based on geostationary satellites with on-board processing generating signals of MCPC (multiple channel per carrier) type. This multiplexing technique allows large system margins. This solution allows the satellite L-band TWTA amplifiers to be operated in saturation and eliminates the intermodulation noise associated with the transmission of FDMA channels. A powerful coding scheme has been selected to create a ‘robust’ down-link. In this way several high-power DAB channels of radio programming, with selectable data rate, are directly delivered to the users.     

On-glass automotive diversity antenna and LNA design for S-band satellite digital radio

Selection combining diversity system with antennas mounted on windshield and backlite of a vehicle is proposed for satellite digital audio radio applications. Standalone exterior mount antennas on metallic vehicles perform well for satellite digital audio radio applications, but for composite body vehicles or interior mount antennas, antenna performance becomes a real issue. Proposed on-glass two-antenna diversity is one solution for such applications. The antenna correlation is calculated using the S-parameters of the antennas and found to be very low due to many wavelengths separation between the antennas. Design of low noise amplifier, which has sub 1 dB noise figure and good P1dB due to strong cellular signals, is also detailed. A diversity receiver is described and ride tests are performed to assess the performance of the diversity system in real-time, under weak satellite signal environment which is regarded as the most challenging reception condition.     

数字化中波同步广播单频网的音频时延分析

随着广播电视技术的高速发展,广播电视信号的传输已经全部实现了数字化,数字化的音频在数字化传输途径中所产生的音频时延有很大的不同.介绍了组成中波同步广播单频网要素,针对单频网中同步发射台音频信号的各种传输途径,阐述数字化音频的各种传输方式,并具体分析每种传输方式所引起的音频信号时延.     

Coded orthogonal frequency division multiplex [TV broadcasting]

Technological evolution and the ever-increasing demand for higher-quality services give broadcasters a strong incentive to completely digitize their broadcasting networks. This digitization, which is already well advanced in many program production areas and transmission links, now has to be extended to complete the last link in the broadcast chain; i.e., from broadcast transmitter to consumer receivers. It is therefore necessary to develop wholly new techniques for the broadcasting of digitally coded TV programmes. Thus an efficient baseband digital coding must be combined with a robust digital modulation and channel coding scheme that can meet the requirements of every mode of broadcast reception. This article presents the research work related to the coded orthogonal frequency division multiplex (COFDM) technology, which has now been completed in the field of digital radio (DAB), and which is under progress in the field of digital terrestrial TV     

全天候、全方位、高质量的数字音频传输系统

本文结合浙江广播电视集团广播数字直播车工程的建设,先简介了直播车的结构和功能,再重点介绍浙江广播电视集团广播数字直播车的创新点,通过对广播现场直播中播出信号传输功能的需求分析和方案优化选择,选用了全天候、全方位的数字音频传输系统,对同类工程建设具有一定的参考意义。     

广播电视工程中数字音频技术的应用分析

广播电视工程中数字音频技术的应用十分重要,它能够有效提升广播电视节目传播水平。在音频处理中,必须与时俱进,追求对数字音频嵌入技术的合理运用,提升音频处理与传输效率,追求对多元化音频内容的合理利用。重点分析数字音频嵌入技术的应用优势,并对多元化应用内容进行分析。     

Analysis of new methods for broadcasting digital data to mobileterminals over an FM-channel

Two new methods using an FM-radio channel for transmission of digital data to mobile terminals are examined: 1. A modification of the radio data system (RDS). In RDS, additional digital information is multiplexed with a stereo sound signal. A new system is suggested where the data signal can be multiplexed with a mono audio signal. This causes extension to the bandwidth available for the data signal, and therefore the RDS bitrate can be increased. Error calculations are performed both for the original RDS system and for the new system. 2. Orthogonal frequency division multiplexing (OFDM). OFDM is used in the digital audio broadcasting system (DAB), which is designed to transmit digital audio in the FM band. In OFDM a signal is divided over a large number of 2- or 4-PSK modulated orthogonal subcarriers. The subcarriers of 6 different programmes are multiplexed in one beam to reduce the effects of frequency selectivity of the transmission channel. A new system based on OFDM is proposed, in which the carriers of each programme are transmitted in one FM-channel with a bandwidth of 200 kHz instead of multiplexed with the carriers of other programmes. Error calculations are performed for the subcarriers used in the OFDM modulation method     

无线广播发展探索

随着电子科学技术不断地更新换代,无线电调幅广播正在逐步向数字中短波音频广播(DRM)和数字音频广播(DAB)直播卫星发展。     

广播电视信号传输中的关键技术分析

随着经济技术的不断进步,科学水平的不断发展,以及先进信息技术在广播电视数据传输中的应用,广播电视已进入数字化、网络化时代。信号传输技术在当前广播电视技术应用中处于核心地位,它直接影响到整个信息传输的质量。主要介绍了广电信号传输中的光纤通信技术、SDH数字技术、卫星传输技术和网络IP技术四种传输方式,希望能对同行起到一定的帮助作用。     

The European system for digital multi-programme television bysatellite

The general concepts of the system for digital television transmission by satellite developed within the European DVB (digital video broadcasting) project and standardised by ETSI (European Telecommunications Standards Institute) are described. The system, named DVB-S, is intended to provide DTH (direct-to-home) multi-programme TV services in the BSS (broadcasting satellite service) and FSS (fixed satellite service) bands and is addressed to consumer IRDs (integrated receiver decoders), as well as collective antenna systems (SMATV, satellite master antenna TV) and cable television head-end stations, with a likelihood of remodulation. The exploitation of the multiplex flexibility allows the use of the transmission capacity for a variety of TV service configurations. The use of flexible and advanced error protection techniques, based on the concatenation of Reed-Solomon and convolutional codes (with Viterbi decoding), allows optimum adaptation to different satellite transponder characteristics, i.e. bandwidth and power, providing high service quality and availability with small receiving antennas. For example, in climatic zone E (in Europe) on a 33 MHz transponder a data-rate of 38.1 Mbit/s can be transmitted, adequate to provide five standard definition TV programmes (SDTV) or, alternatively three to four enhanced definition programmes (EDTV), while ensuring 99.90% service availability (in the average year) with 50-cm receiving antenna within the 51 dBW EIRP (equivalent isotropic radiated power) service area contour     

无线音频技术综述

从FM调频收音机到数字广播,从无绳电话到高保真无线音响,无线通信技术的快速发展显示出对音频传输技术的巨大推动力,各种无线音频新产品、新技术不断涌现。对目前常见的无线音频传输技术和相应的无线音频解决方案进行了介绍,并探讨了无线音频技术的未来发展趋势。     

DigiCipher-all digital, channel compatible, HDTV broadcast system

DigiCipher, an all-digital HDTV (high-definition television) system, with transmission over a single 6 MHz VHF or UHF channel, is described. It provides full HDTV performance with virtually no visible transmission impairments due to noise, multipath, and interference. It offers high picture quality, while the complexity of the decoder is low. Furthermore, low transmitting power can be used, making it ideal for simulcast HDTV transmission using unused or prohibited channels. DigiCipher can also be used for cable and satellite transmission of HDTV. There is no satellite receive dish size penalty (compared to FM-NTSC) in the satellite delivery of DigiCipher HDTV. To achieve the full HDTV performance in a single 6 MHz bandwidth, a highly efficient unique compression algorithm based on DCT (discrete cosine transform) transform coding is used. Through the extensive use of computer simulation, the compression algorithm has been refined and optimized. Computer simulation results show excellent video quality for a variety of HDTV material. For error-free transmission of the digital data, power error correction coding combined with adaptive equalization is used. At a carrier-to-noise ratio of above 19 dB, essentially error-free reception can be achieved     

利用5G技术提升地面数字电视的覆盖效果分析

通地面数字电视是以后数字电视一个关键的传输方法,有着不会受到带宽限制的优势,可是也有着无上行通道、交互性差与现实接收成效不理想等不足。5G这一技术的进步能高效的完善地面数字电视覆盖的不足,处置终端使用者接收的难题,提高广播电视总体的覆盖水准。文章就利用5G技术提升地面数字电视的覆盖效果进行了探析。     

广播电台网间音频传输技术分析和应用

安全可靠的网络间音频文件的传输是电台数字化、网络化后面临的重要问题,介绍了如何安全高效地将音频文件由外部网络传输到电台的制播网络系统中,在保障制播系统安全前提下支持广播节目制作的时效性应用了网间音频传输技术,阐述了对几种网络间音频文件传输技术的分析,总结了几种技术的特点.     

数字化会议系统的分析与设计

采用计算机或单片机为控制中心的数字化会议系统,实现对发言人员次序和摄像机的控制。使用单片机、A／D、D／A等主要器件,利用软件的方法控制与会者的发言．自动分配地址、语音溢出控制和防止自激等措施,实现会议系统的话音采集、传输和处理。与模拟系统相比,控制方便、系统容量大、话音质量好,适合在大型会议等场合使用。