Comparison of solutions for upgrading analog surveillance systems to high-definition systems

    Due to its simple installation method and affordable price, the analog monitoring system currently has a market share of about 70%, but with the continuous advancement of IP network monitoring, its market share and sales are declining. If high-definition network cameras are used to upgrade the original analog system, most of the equipment in the old system needs to be replaced, which not only consumes manpower and material resources, but more importantly, greatly increases the cost of project construction, making high-definition a luxury. In response to this situation, high-definition upgrade solutions such as SLOC, HDCVI, HDTVI, and AHD have emerged one after another to transition from analog to network high-definition. These four high-definition solutions all use coaxial cable as the transmission medium without exception. In addition to promoting the development of high-definition, they also reflect the manufacturers' attention to the "sustainable development" of coaxial cable in the era of analog standard definition.

　　SLOC (Security Link over Coax) composite video transmission technology over coaxial cable

　　SLOC is a technology developed by Sony in cooperation with Intersil Techwell, a US semiconductor manufacturer. On April 6, 2011, Sony announced that it had developed the industry's first hybrid camera that can transmit data over a single coaxial cable with Intersil Techwell, a US semiconductor manufacturer. The SLOC technology solution based on mixed transmission of analog and digital signals consists of a camera modem PHY chip TW3801 based on SLOC technology (TW3802 was used in 2013) and a receiver modem PHY chip TW3811 based on SLOC technology (TW3812 was used in 2013). SLOC technology makes full use of the installed coaxial cable infrastructure and supports networked IP functions, without requiring major changes to IP camera design or DVR design.

　　It can be seen that SLOC is a complete transmission solution developed by Intersil for video cable transmission in monitoring systems. This solution conforms to the development trend of high-definition and intelligent video surveillance, and integrates analog and digital signal hybrid transmission methods, retaining the advantages of real-time analog video transmission. SLOC combines Intersil's traditional advantages in video signal processing and digital-analog hybrid signal processing. It can currently ensure the reliable transmission of analog and IP signals at a distance of 600 meters, greatly extending the distance of traditional network cables or coaxial cables to transmit IP signals or analog signals; SLOC supports IP signals, allowing users to obtain high-definition encoded network transmission images while obtaining the advantages of real-time analog signals, and have IP two-way communication (uplink and downlink dual channels). SLOC can integrate PTZ control of cameras to ensure unimpeded transmission of IP signals on coaxial cables.

　　SLOC provides a new video transmission solution for various manufacturers, and has received support from both home and abroad since its launch. However, it failed to launch a series of products in the security ecosystem, and its promotion and application did not seem to be successful.

　　HDCVI (High Definition Composite Video Interface) high definition composite video interface technology

　　HDCVI technology is similar to SLOC technology, a high-definition video transmission technology based on coaxial cable. It uses baseband modulation and orthogonal amplitude modulation technology to modulate the video into a coaxial million-level high-definition electrical signal for transmission. Based on the existing 75-3 and above video coaxial cable as the transmission medium, it can achieve long-distance transmission at a low cost. This technology successfully solves the problem of chromaticity crosstalk by completely separating the brightness and chromaticity signals. In addition, HDCVI has obvious advantages in intelligent control and real-time performance, especially in terms of upgrade cost control, because it follows the application of analog monitoring technology and simple construction deployment, saving a lot of manpower, material and financial resources.

　　In order to successfully promote HDCVI technology, Dahua has launched a complete set of supporting solutions from front-end to back-end products to fully meet the actual needs of users. As a patented technology of Zhejiang Dahua, HDCVI technology has become widely known after 4 years of development. On March 3, 2014, the International HDcctv Alliance approved the new generation standard HDcctv2.0AT for high-definition surveillance video in Sydney, Australia. Products based on the new AT standard of Dahua HDCVI technology have been widely used in the upgrading of traditional analog products, new solutions for digital HD, and new HD markets.

　　HDTVI (High Definition Transport Video Interface) high definition video transmission interface

　　This year, manufacturers such as Hikvision and Ruishi Technology have also released HDTVI products. The core of HDTVI technology is the HDTVI chip. The transmission chip and the receiving chip are added to the front-end camera and the back-end encoder respectively to increase the data transmission distance. Its image has two digital high-definition video formats, 1280H and 1920H, and effectively carries two resolutions of 1280×720 and 1920×1080. In order to ensure the image quality of the whole machine, the HDTVI's unique automatic compensation function will also be automatically turned on when the coaxial cable transmission exceeds 500 meters, effectively reducing the signal attenuation caused by ultra-long distance transmission.

　　AHD Analog High Definition

　　In order to better compatibility with the original analog system and reduce the difficulties encountered by customers in engineering use, Redun International (Hong Kong) Co., Ltd. launched the AHD analog high-definition series products in 2014 after launching the HDCVI products in 2013. The birth of AHD is to solve the contradiction between the transmission distance and resolution in HD-SDI products.

　　AHD main performance advantages:

　　1. The AHD high-definition camera module uses the original ordinary 75-3 category coaxial line as the transmission medium for transmission up to 500 meters;

　　2. Achieved the ability to carry 720P/1080P resolution videos;

　　3. The front-end data is not encoded or compressed to the back-end, which is real-time and high-fidelity;

　　4. It adopts advanced Y/C signal separation and analog filtering technology, which can effectively reduce color noise in the high-frequency area and achieve better image restoration.

　　Since the attenuation of analog signals in long-distance transmission is inevitable, signal separation technology is used to amplify high-frequency signals. However, another problem is that the degree of signal attenuation varies when transmitting at different distances, and it is impossible to accurately amplify the signal. However, based on the current processing technology, it does not affect general applications. The new AHD product is suitable for places with high requirements for visual monitoring, such as road traffic, schools, and banks, as well as general monitoring places such as supermarkets and homes. With its strong practicality and cost-effectiveness, AHD products will become a major competitor for high-definition solutions.

　　Summarize

　　High definition is one of the most frequently mentioned concerns in the current security industry. High definition is also an inevitable trend in the monitoring industry. However, there are many paths to high-definition monitoring. In addition to the four analog monitoring upgrade solutions introduced in this article, there are also HD-SDI digital high definition and network high-definition monitoring. When looking at the issue of high-definition video surveillance, users should not blindly pursue it. They should take into account current and long-term development and choose a solution that suits them.