Principle and classification of optical transceiver

The optical transceiver is a transmission device in an optical communication system, mainly for performing photoelectric conversion and transmission functions. Generally used in telecommunications, power, monitoring, industrial control, video transmission and other functions, has a wide range of applications in various industries. The optical transceiver is often referred to as an optical transceiver used to monitor the system for transmitting comprehensive information such as video, data, Ethernet, and audio. Mainly divided into analog optical transceivers and digital optical transceivers. The transmission medium is divided into a single mode optical transceiver and a multimode optical transceiver.

The digital optical transceiver digitizes the image, voice and data signals to be transmitted, and then multiplexes the digital signals to convert the multi-channel low-speed digital signals into one high-speed signal and converts the signal into an optical signal. At the receiving end, the optical signal is reduced to an electrical signal, and the restored high-speed signal is decomposed into the original multi-channel low-speed signals, and finally the data signals are restored to image, voice, and data signals. The analog optical transceiver is to amplitude or frequency modulate the signal to be transmitted and then convert the modulated electrical signal into an optical signal. At the receiving end, the optical signal is reduced to an electrical signal, and then the signal is demodulated to restore an image, voice or data signal.

The digital optical transceiver transmits high signal quality, and there is no shortcoming of analog frequency modulation, phase modulation, amplitude modulation, optical transceiver, multi-channel signal transmission, serious interference, environmental impact, poor transmission quality, and poor long-term operation stability. Therefore, the digital optical transceiver will gradually Replace the analog optical transceiver.

At present, in the fields of highway, transportation, monitoring, security, industrial automation, electric power, customs, water conservancy, banking, etc., optical video images, audio, data, Ethernet and other optical transceivers have begun to be widely used. Figure 1 shows a typical application of an optical transceiver.

The optical transceiver is a device that converts multiple E1 (a data transmission standard of a trunk line, usually at a rate of 2.048 Mbps, which is adopted in China and Europe) into an optical signal and transmits it. The price of the optical transceiver is different depending on the number of E1 ports transmitted. Generally, the smallest optical transceiver can transmit 4 E1s, and the largest optical transceiver can transmit 4032 E1s.

Type of optical transceiver

Optical transceivers are divided into three categories: PDH, SPDH, SDH.

PDH (Plesiochronous Digital Hierarchy) optical transceivers are small-capacity optical transceivers, which are generally used in pairs, also called point-to-point applications. The capacity is generally 4E1, 8E1, and 16E1.

The SDH (Synchronous Digital Hierarchy) optical transceiver has a large capacity, generally 16E1 to 4032E1.

SPDH (Synchronous Plesiochronous Digital Hierarchy) optical transceiver, between PDH and SDH. SPDH is a PDH transmission system with SDH (Synchronous Digital Series) features (based on PDH-based code rate adjustment principle, and at the same time, adopts some networking technologies in SDH as much as possible).