Field fiber optic cable is a kind of development military fiber optic cable, which is specially designed for rapid wiring or repeated retractable system use in field battles and complex social environments. The number of cores of the field optical cable is mostly 1, 2, and 4 cores, and the section data structure of the field optical cable.
Field fiber optic cable structure
The single-core fiber optic cable in the fiber optic cable section above is a light yellow cable between two active connector plugs in a commonly used single-core jumper network, many people call it a soft fiber, but its standard name is "single-core indoor fiber optic cable".
Indoor fiber optic cable
Field cables are often used with removable connector plugs because single-core fiber optic cables are ideal for use with patch cords (with removable connector plugs on both ends) or pigtails (with removable connector plugs on one end).
For easy and quick deployment, field fiber optic cables are often used as fiber optic cable assemblies, including: field cables, fiber optic connectors, and retractable racks. For portability, the field cable is smaller in diameter and lighter in weight.
Field fiber optic cable
In order to meet the requirements of rapid wiring and repeated unplugging in the field and complex environment, the field optical cable also has the advantages of tensile strength, pressure resistance, high strength-to-weight ratio, good flexibility, easy bending, oil resistance, wear resistance, flame retardant, wide temperature range, etc. Features.
1. RRU/AAU connection for optical cable development status
The BBU/DU and RRU/AAU of the base station need to be connected by optical cables. However, RRU/AAU are mostly installed outdoors, such as iron towers, etc., and the optical cable connecting with BBU/DU is required to have the characteristics of convenient mobile connection, outdoor use, safety and reliability.
Status of field optical cable
Field fiber optic cable meets these requirements well, so field fiber optic cable is widely used for connection between base station BBU/DU and RRU/AAU.
The connection between the antenna end of the field optical cable and the AAU of the 5G base station.
Base station fiber optic cable
Open the outdoor quick lock fiber optic connector to see the fiber optic cable on the active connector. The active connector plugs into the optical module on the AAU. The field optical cable is far away from the active connector at the antenna end, and is usually directly inserted into the e)CPRI interface optical module of the BBU/DU equipment baseband board (E) in the DRAN mode. In CRAN mode, it may be plugged into the ODF unit of a base station/outdoor network cabinet, or the port of the passive wavelength division multiplexer and demultiplexer, and then connected to the BBU/DU equipment through the access optical cable for ordinary users.
2. The use of RRU/AAU optical cable is confusing
Although the mechanical and protective performance of the field optical cable far exceeds the actual requirements, the operator still feels that it is not enough, and a metal armor layer (the flexible steel pipe below) is added to the field optical cable to make its pressure resistance up to 3000N/100mm;
How to Protect Field Optical Cables
The tensile strength of the single-core optical cable in the field optical cable is low (40N), and it is not resistant to ultraviolet rays. Therefore, when the field optical cable is connected to the AAU, an outdoor quick-lock connector should be used to fix the sheath of the field optical cable to avoid direct stress on the single-core optical cable. However, the height of the outdoor quick-lock connector is less than 10 cm. When the length of the single-core optical cable at both ends of the field optical cable exceeds the height of the outdoor quick-lock connector, the outdoor quick-lock connector cannot be fixed on the sheath of the field optical cable, which will expose the single-core optical cable at the AAU end to the outdoors.
Since the single purchase length of the field optical cable is determined, the commonly used ones are: 40 meters, 50 meters, 60 meters, 70 meters, 80 meters. During construction, the remaining length of each cable shall not exceed 10 meters. Usually a base station (physical station) includes several logical stations, and each logical station needs to lay at least 3 field optical cables, so that the total length of the remaining field optical cables of the base station can exceed 100 meters. The common steel pipe towers on the roadside are basically stuffed with outdoor optical cables.
3. What kind of optical cable is needed for RRU/AAU connection
The RRU/AAU connecting optical cable customized by the operator is not suitable for outdoor use because it contains metal components, so it is actually an armored optical fiber jumper for outdoor use, but we are still used to calling it a field optical cable.
The RRU/AAU optical cable specified by YDT 2289 does not have the characteristics of abrasion resistance, impact resistance, bending resistance, oil resistance and temperature adaptability of the field optical cable. It has lower requirements than ordinary communication optical cables, but requires flame retardancy. The remaining length of the RRU/AAU fiber optic cable can be controlled by field termination of the fiber optic cable at the equipment end (ie, making a flexible connector plug).
The RRU/AAU end cables are still prefabricated at the factory. After the optical cable at the equipment end is cut according to the actual length, just like the FTTH household optical cable, a section of pigtail is spliced on site for termination, and the spliced part is protected by a protective box.
It may be more appropriate to order and name the cables according to industry standards, and cut and lay them to the actual required lengths.
