Two questions are introduced for everyone, a range of digital public address systems, and two digital public address systems. Advantage Digital Network The public address system uses IPAudioTM technology to transmit audio signals over LAN and WAN in standard IP packets. It is a two-way audio sound system for pure digital network transmission. It completely solves the problems of poor sound quality, complicated maintenance management and lack of interactivity in the traditional broadcasting system. The system equipment is simple to use, easy to install and expand, and only needs to connect the digital audio terminal to the computer network to form a powerful digital broadcasting system. Each access point does not need to be separately wired, and truly realizes computer network, digital video monitoring, public broadcasting. Multi-network integration.

The scope of the digital public address system

Large and medium-sized highways, highways, hotel buildings, commercial chain stores, large and medium-sized enterprises, large and medium-sized bus stations, railway stations, "digital IP network broadcasting system"

IP (Internet Protocol) is a network layer protocol in TCP/IP. The IP protocol provides a uniform IP packet format to eliminate differences in communication subnets and is used to provide an interconnection platform for various communication subnets or local area networks.

A system for digitally encoding a broadcast audio signal and transmitting an IP data packet through a network, and then decoding the audio signal by the terminal, which is called a digital IP network broadcast system. With this way of working, multi-network integration can be achieved across LANs and WANs. With a powerful IP network platform, the broadcasting system has ushered in a new leap!

Advantages of digital public address systems

Stronger function

A pure digital broadcast system that covers all the functions of a traditional broadcast system. And make full use of WAN resources, you can get audio resources on the network anytime, anywhere. Since each terminal has a separate IP address, it can control any one terminal to play different programs.

Better sound quality

Due to the use of network transmission technology, the audio signal has no transmission interference and distortion. Adopt MP3 compression algorithm to occupy low network bandwidth (8k-128k) and ensure sound quality fidelity. After testing, use 44.1khz 16bit sampling 128kbps rate compression passband (line output) 20-16khz, distortion ≤ 3%

Simpler installation

easy installation. As long as each factory has the following two conditions: 1) ADSL dial-up Internet access; (2) AC 220V socket and standard Ethernet network access RJ45 socket;

Digital multimedia broadcasting

DMB is the abbreviation of Digital Multimedia Broadcasting, a new concept multimedia mobile broadcasting service that combines communication and broadcasting. Also known as the 3rd generation radio broadcast. In addition to supporting traditional audio broadcasting, this technology will also be able to transmit a variety of multimedia information such as traffic information and news to mobile phones through MPEG-4 H.264 and MPEG-2, AAC+ and other methods. Quality sound quality and diverse data services. Moreover, it adopts the CDM (Code Division Multiplexing) technology which is consistent with the mobile phone, and is particularly suitable for the mobile receiving environment, and can better cope with the problem of multipath interference in which the signal quality is degraded in the mobile receiving environment.

Advantages of DMB:

DMB refers to the digital audio signal and various data service signals, and performs various encoding, modulation, transmission and other processing in the digital state. Since digital signals are processed in various processes, only "1" and "0" are available. Two states, the characteristics of the transmission medium itself, including noise, non-linear distortion, etc., can not change the quality of the digital signal, and at the same time can easily carry out various numerical operations and various logic coding operations, due to the unique advantages of digital technology. Therefore, after introducing or replacing the existing simulation system, the technical operation environment of the existing system is greatly changed, and the overall technical performance index of the system is improved to meet the operational quality and requirements that cannot be realized by the existing simulation technology.

1. Improve the transmission quality of audio signals

Compared with the existing analog system broadcast, due to the high reliability of the digital signal itself, the quality of the sound can be maintained regardless of the quality of the sound signal processing or transmission, so the relative quality can be maintained. In FM, it has hundreds of times or even hundreds of times improvement on several major audio indicators, which can achieve the "CD" quality that people often say.

2, has high power efficiency

Also due to the high reliability and high anti-interference capability of digital signal transmission, the receiver sensitivity can be made higher, so that the transmission power requirement is much lower under the same broadcast coverage requirements as existing FM. According to the DMB technology that we are currently piloting, its six sets of high-quality audio programs share 1KW of power transmission, which is close to the coverage of a single FM broadcast with 10KW. This shows that the power efficiency of the DAB is hundreds of times improved compared to FM.

The substantial increase in power efficiency means more than just energy savings. It is also important to significantly reduce the cost of building a DMB. The reason is that the DMB single channel can transmit up to six sets of high-power DMB programs. The power level requirement is very low. Therefore, compared with the need to separately launch six sets of high-power FM programs, the area occupied by the computer room on the one hand is several times smaller. The capacity of auxiliary power systems such as power distribution, voltage regulation, and air conditioning is also a hundred times smaller. At the same time, it is much easier to invest in a larger antenna system. In particular, the cost of new stations is reduced, and the period of building a platform is also shortened. It is extremely advantageous to promote the use of DMB in a large area.

3, high spectral efficiency

As mentioned above, the digital modulation technique has high spectral efficiency, and with QPSK modulation for DMB to solve the problem of mobile reception, the spectral efficiency is 2bit/Hz.s, which is different in the 1.5MHz RF channel. Send 6 sets of high-quality audio programs, so that in the 8MHz bandwidth of a TV channel, four DMB channels can be conveniently arranged in consideration of the protection interval of each channel, and 24 sets of programs can be arranged, also with the current frequency modulation. The number can basically accommodate more than 60 sets of high quality audio programs. If you consider broadcasting a number of less demanding language programs, the number of programs broadcast at the same time will be much more. This is of course unimaginable under the current simulation system.

In addition, there is an important feature that can easily form a single-frequency network. This technology can achieve large-area coverage of the same content, even across the province, nationwide coverage, which in fact greatly saves frequency resources. , to improve the frequency of reuse, so that the overall consideration of spectral efficiency will be more prominent.

In addition to the above, DMB has the characteristics of anti-multipath interference, fast fading, strong mobile reception capability, and high data transmission capability.

The meaning of the network public address system

The Internet Public Address System is a smart professional device that provides background music, broadcast and fire alarms for public places. Widely used in factories, commercial and residential communities, schools, plazas, commercial buildings, hotels, etc. At present, the most important feature of public broadcasting systems is the application of digital technology to public broadcasting systems, which makes the installation of public broadcasting systems more convenient, more powerful, more widely used, and easier to operate.

The network public address system adopts the full digital system and is relayed by the front-end equipment (preamplifier, telephone access device, alarm generator, digital program control host, program-controlled keyboard, modulator, program power timer, music source, monitor, etc.) , terminal equipment (speakers, speakers, residential constant pressure amplifiers, etc.).