From a structural point of view, marine communication cables are generally divided into two parts: cable core and sheath. The protective layer can be divided into a sheath and an outer protective layer. The cable core is composed of an insulated conductive core wire and necessary shielding, filling and binding tape (wire). From the appearance point of view, the cross-section of the cable core is generally circular.

The core of the marine cable is the main part responsible for information transmission. In order to protect the cable core from moisture, external mechanical damage and electrical interference, a sheath is added to the outside of the cable core. If necessary, additional outer protection is required. layer.

In the past, lead was often used as a sheath. This is because lead is relatively soft, easy to manufacture and install, and can also have a moderate shielding effect. But as technology develops, many choose to use aluminum. This is because lead is too heavy. Shipping is very difficult. The shielding effect of aluminum is better than that of lead, and it is much lighter. Of course, everything has pros and cons. Aluminum is more difficult to manufacture than lead and is susceptible to corrosion.

In dry environments, metal-free polyethylene or polyvinyl chloride sheaths can also be used.

Communication cables laid underwater will have a steel wire armored outer sheath, and an anti-corrosion layer will need to be added to the metal armored layer.

The body needs to be covered with a shielding layer and then twisted into cables. The shielding layer is mostly double-layer wrapped steel tape.

     Metal shielding is an important measure to weaken and prevent electrical interference, including total shielding, sub-shielding and double-layer total shielding of wire cores. The selection of the metal shielding type of marine control cables should be based on the intensity of the possible electrical interference, and comprehensive interference suppression measures should be taken into account to meet the requirements for reducing interference and overvoltage. The higher the requirements for anti-interference effect, the greater the corresponding investment. When steel tape armoring and steel wire braiding are used for total shielding, the price of the cable increases by approximately 10% to 20%.

     For control interference in strong current circuits, due to the strong signal itself, control cables without metal shielding can be used unless they are located in ultra-high voltage power distribution devices or are close to and parallel to high-voltage cables. When the control cable used in the weak current signal control loop is located in an environment affected by interference and does not have effective anti-interference measures, it is recommended to use a control cable with metal shielding to prevent electrical interference from causing malfunctions in the low-level signal loop. Or cause insulation breakdown and other effects. If the marine control cables of weak current loops can be kept at a sufficient distance from the power cables or laid in steel pipes, external electrical interference may be reduced to the allowable limit.