How to choose video surveillance cables? Precautions for selecting video surveillance cables

Video surveillance cables are the video transmission medium used in security systems. There are many types and materials, and the quality of cables has a great impact on the quality of surveillance videos. Therefore, choosing a high-quality surveillance cable is particularly important. So, how should we choose a video surveillance cable? Here are a few precautions for purchasing video surveillance cables for reference.
Video signal transmission generally adopts direct modulation technology in the form of baseband frequency (about 8MHz bandwidth), and the most commonly used transmission medium is coaxial cable. Coaxial cable is specifically designed for transmitting video signals, with relatively small frequency loss, image distortion, and image attenuation amplitude, which can effectively complete the task of transmitting video signals. Generally, specialized SYV75 ohm series coaxial cables are used, with the commonly used model being SYV75-5 (which has a non relay transmission distance of 300-500m for video signals); When the distance is far, coaxial cables such as SYV75-7, SYV75-9, or even SYV75-12 need to be used (in practical engineering, the non relay transmission distance of thick cables can reach more than 1km);
1、 Enterprise Qualification and Product Quality Inspection Certificate
When users or engineering companies choose security cables, the first thing they need to pay attention to is the enterprise and product qualification materials. They need to understand the following types of qualification certificates of the production enterprise: business license, organization code certificate, tax registration certificate, etc., which can indicate the scale and strength of the production enterprise and the enterprise level, national industrial product production license (wire and cable) The CCC China National Compulsory Product Certification Certificate, the Network Access Certificate of the Ministry of Information Industry, ISO9001 Certification and other certificates are all necessary production and operation licenses and indicators of the quality management level of the production enterprise. Quality inspection reports from national authoritative departments within their validity period, other certificates or documents such as industry membership certificates, honor certificates, recognition certificates, patent certificates, etc., are powerful proof of the user awareness, influence and overall strength of the production enterprise in the industry.
2、 Cost effectiveness and service
When users purchase security cable products, after understanding and carefully reviewing the relevant qualification certification materials of the production enterprise, the next step is to comprehensively measure the performance and price of the product, as well as the service and supply guarantee capabilities.
As an engineering company or direct user, it is inevitable that we hope to achieve maximum efficiency and value at the most reasonable price while the product quality is almost the same. At present, various specifications of cables required for security system engineering can generally be guaranteed by mainstream security cable companies in the industry. So some users blindly praise foreign brands, and the consumption concept of buying cable products at high prices is irrational. Similarly, blindly pursuing low prices while neglecting product quality is also not advisable. It should be fully recognized that according to the laws of market economy, reasonable prices mean reasonable quality assurance.
3、 On site inspection by the manufacturer
When selecting cable products, it is also important for users to conduct on-site inspections of the manufacturer's scale and production base. There is a saying that goes, 'Hearing is believing, seeing is believing.'. The special performance of cable products determines the professionalism of cable testing methods. Generally, users are accustomed to judging the quality of cables based on their appearance and feel, but their true technical performance and parameters must rely on professional cable testing equipment to achieve.
The quality of cable products is mainly determined by the following aspects: procurement of raw materials; Production and testing equipment; Production technology and process control. Users can understand the degree of cable quality assurance from the above points during on-site inspections of production enterprises.
4、 Product acceptance and quality identification
Users can identify products from the following aspects during acceptance to determine whether they meet the standards. Considering that it is unlikely for users to have professional testing equipment, several simple and effective methods are introduced:
1. At present, the main materials for security cables are copper and polyvinyl chloride (PVC). It is possible to distinguish the quality of materials with the naked eye.
2. Structural process testing
Users can peel off the outer sheath of the cable for structural and process testing during product acceptance. You can focus on checking the following items:
1) Whether a considerable proportion of copper conductors are twisted or not is an important process omitted by non-standard manufacturers. Failure to twist copper conductors can result in unstable conductor structures and cable bending
In this state, construction can easily cause insulation cracking or conductor piercing through the insulation layer.
2) Is the cable pitch too large? The cable pitch refers to the distance between the nodes of a multi-core cable after the core wires are twisted during the production process. Some manufacturers aim to control costs and improve production speed
Degrees often enlarge into cable pitch. So the softness and curvature of the product are poor, and the internal structure is unstable, which reduces the performance of the cable product
3) The insulating plastic should be tightly extruded and wrapped around the conductor without damaging it, and the conductor should not deviate from the core.
4) The outer sheath should be tightly wrapped around the internal structure, and the gap should not be too large. There is a polyester coating between the outer sheath and the internal structure to effectively prevent adhesion between them.
5) The quality of the shielding structure in shielded cables is extremely critical for products in security system engineering. Require tight, regular, and smooth coverage. In addition to the high production process requirements of the manufacturing enterprises, the production equipment is very critical in this project. Currently, several major domestic security cable companies use high-precision PLC controlled weaving machines. The products produced by such equipment have stable structure and regular arrangement, ensuring excellent shielding performance.
6) The outer diameter size is uniform and the roundness is still acceptable. The vast majority of security cables are used in engineering projects, and production companies mainly consider the stability of product structure, excellent and reliable transmission performance, so the roundness of the appearance is generally not deliberately emphasized.
3. Professional equipment testing
A more accurate detection method is to increase professional testing equipment or commission specialized institutions to conduct product testing. The routine testing items and testing equipment are as follows:
Voltage endurance test - Voltage endurance test bench
Structural inspection - projector or measuring microscope
Conductor Resistance - DC Bridge Instrument
Single wire diameter of conductor - micrometer micrometer
Power on test - multimeter
Tensile strength - tensile machine
The above is a complete introduction to the precautions for purchasing video surveillance cables, hoping to be helpful to everyone