How to buy the digital optical transceiver with the best price-performance ratio for the contractor (Part 1)

At present, there are many types of digital video optical transceivers on the market, and the technical indicators involved are even more dazzling. Manufacturers of various sizes are everywhere, and it is difficult to determine the technology and product quality. Most engineering companies and users also lack corresponding detection methods, unable to judge the rationality and authenticity of the technical indicators and the comprehensive strength of the manufacturers, so it is easy to get lost or even confused when choosing products.

Today, we will focus on how to consider the cost-effectiveness of products in the face of numerous digital video optical transceiver products, how to integrate their company's comprehensive strength, technological advancement, technical indicators, practicality, reliability and other issues when purchasing.

1. The company's comprehensive strength

As an engineering company or a large-scale project operator, digital video optical transceiver products may be used for a long time. However, the performance indicators of video optical transceivers and the comprehensive strength and quality assurance capabilities of manufacturers are relatively poorly understood. How to choose products and manufacturers so that there will be as few quality problems as possible in the future use process, and reduce the dismantlement and replacement of equipment on the site in the later stage, so that the end user's dissatisfaction? The following opinions are available for reference:

1. The company's relevant qualifications

For the company's registered capital and assets, this can be obtained from the company's business license or inspected on site (if conditions permit). If the company's capital and strength cannot be guaranteed, it is difficult to guarantee the delivery of products and the subsequent service measures in place.

2. The company's ISO9001 international quality management system certification

The quality management system is a systematic method of management around the whole process of product realization, from the initial stage of product design to the final delivery of the product. But now there are also many small companies with 2-3 individuals. In order to obtain the entry qualification for type selection bidding, they do not hesitate to buy ISO9001 quality management system certification.

3. The company's product quality testing equipment

At present, domestic video, audio and data detection instruments are priced at 100,000 or even up to 1 million. Many small companies simply do not have the strength to buy, but these instruments and meters play a vital role in product quality. Therefore, this point can be used as the focus of investigation. (Eg: Tektronix VM700, audio analyzer, bit error analyzer, etc.)

4. Product certification

As a product of the security industry, it is generally necessary to go to an authority of the Ministry of Public Security for authoritative testing. The test report issued by a third-party testing organization should be credible. If considering from the aspects of product safety and electromagnetic compatibility, there should be certification in this respect. If it involves export products, there are European CE certification, European ROHS environmental certification, etc. (Where CE certification covers product safety and electromagnetic compatibility)

Second, the technical advancement of the product

1. SNMP network management software

At present, the application scope of digital video optical transceiver products should be said to be very extensive, but now there are few video optical transceivers that can support network management functions in China. SNMP network management will save customers a lot of maintenance costs and provide work efficiency. At the same time, it monitors the working status of the remote equipment, and problems can be discovered and resolved as soon as possible.

2. Rich interfaces and multi-network integration

Many manufacturers on the market still use traditional digital optical transceivers. The single interface technology is outdated and cannot provide multiple interfaces at the same time. Many manufacturers even use analog optical transceivers to pretend to be digital optical transceivers and sell them to customers to deceive consumers.

3. Standard modular design to meet different needs of customers

Good scalability, to avoid repeated investment by customers.

3. Technical Specifications of Video Optical Transceiver

1. As mentioned above, if a third-party test report is available, a qualified and qualified engineering company should retest according to the indicators provided by the manufacturer before purchasing the equipment to verify the actual technical indicators of the equipment and integrity.

2. 8M video bandwidth

Video bandwidth is an old issue. If the video bandwidth is insufficient, the details of the monitoring screen will not be clear enough, the horizontal resolution will be low, and even serious color distortion or loss. Due to the importance of video bandwidth to image quality, some manufacturers deliberately exaggerate the product's video bandwidth to deceive customers. Some manufacturers of digital video optical transceivers claim that their video bandwidth is 8M, but the video sampling frequency announced by them is 12.5M. According to Nyquist sampling law, to truly restore the signal, its sampling frequency should be at least twice the signal frequency. In this way, the theoretical video bandwidth of this manufacturer's optical transceiver cannot exceed 6.25M anyway.

3. APL, that is, the average level of the image, many engineers are not very careful or familiar with this indicator

However, if it is said that some projects encounter such a problem: the video signal is transmitted through the optical transceiver, and when there is a large area of ​​white in the picture (such as when the camera is illuminated by strong light), the picture on the monitor will shake horizontally, then the project The personnel must be familiar. This is because the APL range of video optical transceivers produced by some manufacturers is too narrow. When there is a large area of ​​white in the image signal, the DC component of each line of image signal increases, and the APL will increase, which causes the line sync signal amplitude to decrease or Loss, the monitor cannot detect the line synchronization and the screen jitter occurs.

4. Practicality

When choosing an optical transceiver, users and engineering companies can consider more from the perspective of the practicality of the equipment. First, it is easy for users and engineers to judge the practicality issues; second, it is difficult to believe that manufacturers who cannot do good practicality can do a good job in the reliability and technical indicators of optical transceivers. Here we focus on the practicality of the optical transceiver from the following angles.

1. Elegant appearance and reasonable structure

The digital video optical transceiver has high technical content, its appearance is small and exquisite, beautiful and elegant, and the overall structure must meet the engineering installation requirements as much as possible. In addition to the 19-inch and 4U plug-in card rack, the general indoor digital video optical transceiver should also take into account the need to place the optical transceiver on the desktop or on the wall in the project. In addition, the digital video optical transceiver must also have good heat dissipation performance and electrical contact performance.

2. Rich interfaces and reasonable layout

In addition to requiring sufficient video interfaces, digital video optical transceivers may also require or may be required to be equipped with other feature-rich interfaces, such as high-fidelity audio, asynchronous data, Ethernet, E1, telephone, switch, etc., which requires the selection of The digital video optical transceiver must have the ability to upgrade the system, so as not to completely replace the device due to network upgrades or system function changes, thereby protecting the user's previous investment.