The fiber optical link can achieve long distance, fast speed, and low latency network. Unlike the copper network which is limited to 100 meters, the fiber optical link can reach beyond 10KM without using any network extender. In the typical fiber optical link, there are media converters, SFP transceivers, and fiber optical cable. The media converter and the SFP module (aka SFP transceiver) will convert the optical signal to the digital signal, or vice versa. Usually, it works in pairs sitting at point A and point B. It could save one of the media converters if the switch has built-in SFP slots that can take the SFP modules. The SFP modules are being sold separately, you may still need one pair of SFP transceivers. The SFP modules determine the cable connector and the type of fiber optic cable. The LC connector and the SC connector are the most common type. We recommend the single mode fiber optical cable because the distance is longer from the single mode. You will see multiple mode fibers on the data center or the backbone network. Making fiber optical cable connectors could be challenging but you can use the factory pre-made cable to save the trouble.
There is one thing people may ignore in the fiber optical system is the power source. The media converter and the SFP module are low voltage electronic products but they need a trpower source. There is a sincerely mature network power solution – Power over Ethernet (PoE) in the copper network. However, the PoE can’t be implemented in fiber optical systems. Technically, the fiber optical system makes use of light to carry the signal. The fiber optical is made of plastic and the power can’t be injected into the plastic. We will see how to deal with the power in the fiber optical system.
AC to DC Power Adapter
If the power source is available at the edge, you will just need a power adapter to supply the power for the media convertor. The media convertor can’t take the AC power. The power adapter can convert the AC to low voltage DC power. Media converters are low power consumption devices, thus power budget should not be a concern, but you may be supposed to pay attention to the voltage. Some of the media converters only can take in DC5V. If the DC12V or 24V is attached to the media converter, it is going to damage the media converter. The power source of your edge devices behind the media convertor may need to be considered as well. Most of the IP cameras and outdoor access points need DC12V. It is a good idea to unify the voltage at the edge rather than to have a different voltage. The power adapter may affect the useful life of the electric products. While the media convertor is being deployed outdoor, the power adapter becomes critical. If the voltage output is not stable, the media convertor could become unstable as well. Choose the power adapter which can endure a wide range temperatures for outdoor deployment.
Solar Panel Power System
The AC power is not always available at the edge and the fiber optical link can achieve up to 10 KM. Sending the AC power over a long distance to the edge will be difficult. The solar panel power system is one of the optional solutions. Basically, you will need a solar panel, battery, and charging controller to build the solar power system. The battery is always required to keep the power. The solar pane can’t be attached to the edge device or media converter directly. The charging controller will control the charging process to the battery. The solar panel can’t be attached to the battery directly either. The voltage will keep changing based on the intensity of sunshine. The controller not only will determine the overcharge, but also regulate the input voltage into a specific range. The cloudy day needs to be considered while picking the solar panel and the battery. For example, how long the battery can supply for keeping the edge device running if there is no sunshine.
Some of the solar panel power systems are designed for lighting. One of the typical characters of lighting is it is not supposed to be working at day. The solar panel can recharge the battery and keep it run up at night. However, your edge device may need to work 24/7. The worst case is the solar panel may never have enough power to keep running after the battery runs out. There is no buffering time to keep the battery charging. Imagine you have a bucket taking the raindrop, there is a small hole near the bottom of the bucket. If the leaking out is fasten then dropping in, the edge devices may keep switching between online and offline. It is important to set the proper resume voltage to make sure the battery will not output the power immediately after it run out.
Sending Power in Parallel
The Power over Ethernet (PoE) take the advantage of copper cable to send both power data. We can’t inject the power into the fiber optical cable. Instead, we could wire copper cable in parallel to supply the power for the edge devices especially while the distance is less than 2KM. The power loss is the first thing we need to deal with. The longer the distance, the severe the power loss will be. The power will lose inline and convert into heat, leading to a consequence of voltage drop. The remaining voltage is not enough voltage to supply the edge device. Referring to the Power over Ethernet, we can send the higher DC voltage such as DC55V which is still safe to the human body to adapt to the voltage drop. A thicker copper cable such as 16 AWG or 14AWG can be employed to send the power. The thicker the copper, the smaller the power loss will be. The specification of the Ethernet cable is about 22AWG. While 16 AWG is being used, it can achieve 2000 meters distance with 12W power.
In some applications such as IP camera systems, the voltage will change dynamically. While the infrared is turned on at night, the voltage drop will become more serious. The media converter with a built-in voltage regulator can adapt to the voltage drop. Even the voltage drops down to 24V, the output still can be regulated to DC54V. Sending DC power from back-end save the trouble to deal with the high voltage AC power which is not safe to the human being.
