Top 10 Common Questions about Telephone Optical Terminals

Summary: Based on years of experience in the production and R&D of telephone optical terminals, Raytrans Digital summarizes the top 10 common questions about telephone optical terminals and provides solutions, offering assistance to industry peers in the selection and maintenance of telephone optical terminals. Corrections are welcome.

I. Specifications of Telephone Optical Terminals
There are many specifications for telephone optical terminals, but none are critical. The only somewhat useful one is the transmission distance. Generally, optical terminals can transmit 20-60 km. For longer distances, simply replace the optical port module. Another factor is the optical port connector type; the most common are FC (round) and SC (square). When ordering, it is necessary to confirm whether pigtails are included.

II. Is There a V.35 Interface
Generally, optical terminals do not have a V.35 interface.
The V.35 interface has only become a market requirement in the past two years.
The V.35 interface is a synchronous data interface with a rate of NX64 kb/s.
Typically, one E1 channel is used to transmit one V.35 interface.

III. Ethernet Interface
Generally, telephone optical terminals do not have an Ethernet interface. Optical terminals with Ethernet interfaces are a new market demand in the past two years.
One E1 channel can transmit 10M Ethernet signals.
Four E1 channels can transmit 100M Ethernet signals.

IV. Number of Optical Ports 3: Dual Optical Ports for Dual Directions
Part of the signal from the left optical port is dropped locally, while the other part continues to be transmitted from the right optical port. This working mode is called add/drop multiplexing (ADM). Optical terminals with ADM capability can form a dual-fiber self-healing ring.

V. How to Evaluate the Performance of Telephone Optical Terminals
Number of optical ports and optical directions.
Number of E1 channels.
Availability of Ethernet interface.
Availability of V.35 interface.
Availability of V.11/V.24 interface.
Availability of service telephone.
Availability of network management.
Networking capability: whether a self-healing ring can be formed.

VI. Network Management System for Telephone Optical Terminals
Network management refers to computer network management, also known as centralized monitoring. It involves connecting the operational status information of optical terminals at all stations to the network management computer in the central office's network management room.
Generally, PDH optical terminals do not have a network management system.
Generally, SDH optical terminals have a network management system.

VII. Fiber Optic Interface
The fiber optic interface is the physical interface used to connect fiber optic cables. There are typically several types, such as SC, ST, and FC, which were developed by NTT Corporation of Japan. FC stands for Ferrule Connector, with a metal sleeve for external reinforcement and a screw-type fastening mechanism. ST interfaces are typically used for 10Base-F, while SC interfaces are typically used for 100Base-FX.

VIII. Bandwidth of Telephone Optical Terminals
The bandwidth of optical terminals is classified as 10M/100M/1000M. Video optical terminals can also incorporate Ethernet, but the bandwidth often reaches a maximum of 100M. Telephone optical terminals can also add Ethernet, but the bandwidth can reach higher levels.

IX. Signal Level of Telephone Optical Terminals
Signal level refers to the logarithmic value of the power ratio between the output signal and the input signal of the device, typically denoted as P, where P=lgP2/P1.

X. Configuration of Telephone Optical Terminals
The configuration of optical terminals is primarily determined by engineering design and actual requirements. Optical terminals mainly transmit video, audio, and control signals, so the configuration is also divided according to these aspects.