Demand analysis In order to improve its ability to respond quickly to emergencies and improve the efficiency of day-to-day policing, a municipal bureau has built a mobile image transmission network project. The project has achieved coverage for multiple counties, main urban areas and some suburban areas. It meets mobile multimedia emergency transmission needs of relevant business departments through mobile network communication and multimedia technology, and timely collects live first-hand images and audio in real time. Transmitting it to the commanding departments at all levels has important social significance for security, anti-terrorism, sudden crimes, maintaining stability, and ensuring the safety of people's lives.
In order to better help improve the efficiency of accident emergency command, save maintenance غير مجاز مي باشدts, according to the customer's technical requirements, the Division produced a wireless image transmission system program.
The wireless mobile emergency command image transmission system aims at customer satisfaction and must have high reliability and practicality:
1. Implementing unified access to mobile video transmission calls to establish a unified wireless video transmission video networking platform to realize interconnection of mobile video data sent back by multiple sets of graphics transmission devices, and to achieve flexible terminals for all terminals in the platform. For the optional, visual, and intercom, the relevant leaders can keep abreast of the situation on the spot so that appropriate preventive and remedial measures can be taken to ensure social stability.
2. The realization of fast and unified command and dispatch realizes two-way remote video monitoring and audio and video two-way interactive video command and dispatch platform. The municipal office can flexibly invoke each way of moving images and share them with designated bureaus and branch offices. At the same time, it can achieve real-time control of the scene. At the same time, the city bureau can also use this platform to map mobile maps distributed in counties (districts). The pass-by-pass wireless video transmission device delivers real-time voice commands, and implements the presentation of emergency visualized command and dispatch and daily duty management instructions for the release and reporting of subordinate situations.
To achieve platform-level command and dispatch management, users can perform flexible level management based on their own affiliation, and realize the management and configuration of command, monitoring and control rights, and meet the needs of all levels of departments to establish an effective command and dispatch relationship.
Overall system design plan I. Overall structure
Second, system composition and description The entire system can be divided into two parts of vehicle system and system platform.
1. Main equipment of on-board system: It is divided into TDD base station main control end and TDD vehicle-mounted controlled end;
Antenna feed system: including various types of omnidirectional or directional transceiver antennas, RF feeders, etc.;
Functional integration: including vehicle-mounted PTZ video capture, display, capture, recording terminal, video conferencing, telephone communications, GSP information, data monitoring, and various audio terminals;
Data interface: Ethernet RJ45 interface, RS232 interface for two-way data transmission.
Central Management Software: Completes management functions such as registration, call, logout, communication, bandwidth, video, query, and monitoring at the controlled end.
1) The command center command center and the base station are connected via optical fiber, and the remote real-time image of the communication vehicle is connected to the command center room through the video matrix HDMI interface (HD) and BNC interface (SD), displayed in the command center on a large screen; voice input through the mixer The 3.5mm audio female head is connected to the command center room, and the voice output is connected to the HD decoder 3.5mm audio female head through the console output.
Product features: support system with the same frequency networking; a single command center wireless router supports four simultaneous two-way audio and video, data transmission; modular low-power design, built-in cooling fan; power stability, dynamic power adjustable, covering a long distance; The wireless channel uses AES 128-bit encryption. With special software, it will have digital spectrum scanning function, which can detect the surrounding electromagnetic environment, find the interference frequency, and provide favorable basis for adjusting the frequency; the working frequency, bandwidth, code stream, etc. can be adjusted according to the actual use; flexible allocation of channels Resources, to achieve point-to-point, point-to-multipoint, multi-point to multi-point two-way communication, a variety of time slot mode is adjustable; uplink and downlink bandwidth is adjustable, the maximum bandwidth of up to 14M.
2) The base station is set up to set up multiple fixed base stations at each high point in each district of the city, which can be implemented by using our company's SF-TJ340-20W co-frequency networking two-way base station equipment. The wireless emergency communication base station adopts indoor and field base station design. Each base station can transmit data remotely according to actual requirements, and transmits signals to the command center through optical fiber or other wireless means. All layout base stations, interconnection and intercommunication, multi-level password management, base stations Portable quick installation, a variety of application methods.
Basic Information Field Base Station Frequency: UHFMHz Transmit Power: 43dBm Base Station Antenna Height: 50m Antenna Gain: 11dBi
Coverage radius: 12~16km (suburbs)
Urban base station frequency: UHFMHz Transmitting power: 43dBm Base station antenna height: 70m Antenna gain: 11dBi
Coverage radius: 7~10km
3) Communication vehicle planning communication vehicle, through the installation of our company's SF-T331-10W two-way vehicle equipment to achieve wireless two-way data transmission. The communication vehicle equipment adopts a portable cabinet design and can be quickly deployed to the current vehicle. The portable cabinet integrates vehicle-mounted wireless graphic transmission terminals, storage devices, display devices, and control devices. Built-in not less than 1KW inverter, take power directly from the car.
Antenna erection reference equipment vehicle cabinet installation diagram
The video and data collected by the IPC on the communication vehicle are input to the TDD wireless vehicle-borne routing transmitter through the network cable, and transmitted to the remote wireless command center via microwaves to realize remote real-time monitoring of the site and two-way video and audio data transmission. The distance can reach more than 15 kilometers (the transmission distance and the erection of the antenna, the local environment and the amount of data transmitted). Of course, the video, audio, data, conference system, and instructions of the command center can also be used to place computers, large-screen display devices, and audio equipment on mobile communication vehicles.
Product features: support system with the same frequency network; two-way audio and video, IP data non-line-of-sight transparent transmission; modular low-power design, built-in cooling fan; power stability, dynamic power adjustable, transmission distance; wireless channel using AES128 encryption. With special software, it will have digital spectrum scanning function, which can detect the surrounding electromagnetic environment, find the interference frequency, and provide favorable basis for adjusting the frequency; the working frequency, bandwidth, code stream, etc. can be adjusted according to the actual use; flexible allocation of channels Resources, to achieve point-to-point, point-to-multipoint, multi-point to multi-point two-way communication, a variety of time slot mode is adjustable; uplink and downlink bandwidth is adjustable, the maximum bandwidth of up to 14M.
2. System platform 1) Monitoring platform software Wireless mobile emergency video communication dispatching platform management and control software is a complete network monitoring dispatch management system that can manage all configured wireless devices in the system, with monitoring images, voice dispatch, and head Control and other functions.
The specific functions are as follows:
1. Real-time video display: Real-time display of real-time video images of 1-16 channels in the surveillance network. It can realize single-screen, 4-screen, 6-screen, 8-screen, 9-screen, and 16-screen display, and supports round robin display.
2. Remote recording: You can store video files to the built-in hard disk of the front-end video server.
3, local video: You can automatically video according to the set video time.
4. Real-time video image capture: Real-time image capture is an auxiliary function for real-time image capture. It saves a single frame image in a dynamic image in the BMP image format, and captures the image being monitored or being played back.
5, audio monitoring and intercom: the client and the front-end device can be two-way voice transmission. The client can listen to the audio of the front-end device, and the client can send the audio to the front-end device and implement the intercom with the front-end device.
6. Electronic map display: The electronic map contains the name of the monitoring scene and the front-end equipment in the scene. Clicking on the front-end video equipment icon distributed on the electronic map displays the real-time image of the equipment.
7. Local playback: You can retrieve the video files of the device in the local video at any time.
8, matrix control: analog matrix function, real-time image switching display on any monitor.
2) Device Control Software The wireless mobile emergency video communication dispatching platform control software is used to control the channel parameters, modes, time slots, AES passwords, etc. of the TDD device.
The specific functions are as follows:
1. Basic information of the device The basic information of the device is displayed. It displays the status of the device when it is shipped from the factory, including the device type, serial number, factory time, FPGA version, and the version of the SCM. This part belongs to the display function and the user can only view it. modify.
2. Channel parameter setting Channel parameter setting, this part of the equipment has already been debugged according to the normal setting when leaving the factory, but can be set and modified according to different needs of the customer.
3. Receiving status display The receiving status display shows the power value received from the remote base station through the antenna and received by the receiving terminal of the central base station. 4. The data rate display data rate display is used to check the uplink and downlink data rate and the working time slot mode of the device. .
5, AES key AES key settings 6, channel mode settings can be set by clicking on four different interleaving modes, namely: no interleaving, short interleaving, interleaving, long interlacing three, system technology introduction 1) VTECH-MobileDVCSystem technology brief VTECH-MobileDVC adopts TDD two-way networking transmission technology and integrates the latest LTE mobile communication and terrestrial digital TV DMB-T technology features and advantages. It independently researches and develops a new generation of multiple access wireless communication technology and adopts the current multi-user wireless communication field. Advanced code modulation, TDD-OFDM, LDPC error correction codes, DPD, H.264 codec and other technologies are the core. The allocation of channel resources is flexibly assigned to multiple user terminals through subcarriers through time slot control and frequency. Maximize multiple terminal user multiple access within the same frequency point. Real-time bidirectional transparent information transmission in high-speed motion under non-line-of-sight conditions, multiple wireless networks can be integrated with each other to layout large network coverage.
Source: The main purpose is to use the statistical characteristics of the source to solve the correlation of the source and remove the source redundant information so as to achieve the purpose of compressing the information rate of the source output and improving the effectiveness of the system.
Channel: In order to ensure the transmission reliability of the communication system, to overcome the noise and interference in the channel. It adds some necessary (supervisory) symbols to the information symbols to be transmitted according to a certain (supervisory) rule, and uses the supervising rules between these supervised symbols and information symbols at the receiving end to find and Correct errors to improve the reliability of information symbol transmission. The input data stream passes through a scrambler (randomization), forward error correction coding (LDPC), and then performs constellation mapping from bitstreams to symbol streams, and then interleaves to form basic data blocks. After basic data blocks are combined (multiplexed) with system information, frame body data is processed to form a frame body. The frame body and the corresponding frame header (PN sequence) are multiplexed into a signal frame (a framing frame) and converted to a baseband output signal (within a bandwidth of 8 MHz) after baseband post-processing. TDD timeslot control is used to control orthogonal upconversion to RF signals (in the UHF and VHF bands) (110MHz-1000MHz). Instead TDD control is received.
2) System technical characteristics
Advanced: TDD-OFDM channel modulation technology, with high-speed mobile, ultra-wideband, all transparent transmission security: private network, using private communication transmission protocol, unique synchronization code, AES encryption flexibility: transparent transmission of IP data channels, support for multiple users Access scalability: All-digital network, compatible with all IP data transmission equipment Multi-base station inter-frequency networking, single-base station co-frequency networking, bi-directional communication with base stations in the same frequency band, high spectrum utilization, flexible allocation of channel resources, and point-to-point Point-to-multipoint, point-to-multipoint, multipoint-to-multipoint two-way communication Multiple channel modulation bandwidth and multiple modulation modes Flexible TDD time slot allocation mode to meet single frequency multi-user access, save spectrum, reduce power consumption spectrum with the same power Perception, Slot Perception, Upstream Bandwidth Sensing Strong Diffraction, Anti-Multipath Capability, Excellent Diffraction and Penetration Capability Receiver Sensitivity is High, and Bit Error Rate <10E- at Receive Level -110dBm 5, error frame rate <1%
Powerful error correction capability Low peak-to-average ratio, high power amplifier efficiency, low power consumption, high-speed, real-time, and synchronous transmission of multimedia information such as video, audio, and data, and the speed of movement is greater than 300km/h;
With wireless broadband ASE 128 bit density technology, all digital signal processing, system confidentiality, stability and reliability
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