Technical Fundamentals

Q: How does all-digital uncompressed video technology ensure the picture quality of 8 video channels?

After the video signal completes A/D sampling at the transmitter it is transmitted directly in digital form, and the receiver performs D/A conversion to restore it; the link contains no encoding or decoding stage and therefore introduces no picture quality loss or stream jitter caused by compression algorithms. The video signal-to-noise ratio (SNR) of the IDM-VDA8200 8-channel video optical multiplexer is ≥70 dB (weighted), its luminance non-linearity is <3%, its differential gain (DG) is &lt

Question 1

How Far Can a 1-Channel Video Optical Terminal Transmit, and How Is Link Distance Calculated?

Accepted Answer

The standard transmission distance of a 1-channel video optical terminal is 20Km, based on single-mode fiber and FC optical port, with wavelengths of 1310nm/1550nm. To determine whether a link is usable, compare the transmit optical power (-15~-8dBm) with the receiver sensitivity (better than -32dBm, 1310nm); the difference between the two is the available optical power margin. In actual engineering, fiber attenuation and connector loss must also be included in the calculation. Fiber mode and in

Question 2

What interfaces does a 1-channel video optical terminal provide, and what services can be transmitted simultaneously over one fiber?

Accepted Answer

The service interfaces of a 1-channel video optical terminal are stacked by model: the video channel uses a BNC interface with input/output impedance of 75Ω (unbalanced); the data channel uses an RJ-45 interface supporting RS-232, RS422 (4-wire), and RS485 (2-wire); the audio channel uses an RJ45 interface with input impedance ADC:100KΩ and output impedance DAC:10KΩ, connected according to port labels. The optical link side features an FC optical port (SC and others customizable), with single-mo

Question 3

How far can a 2-channel video optical multiplexer transmit? How should the optical port and the optical fiber be matched?

Accepted Answer

The standard configuration of the IDM-VDA2000 series 2-channel video optical multiplexer provides a transmission distance of 20 km, and a long-distance optical module can be fitted when a longer link is required. The transmit optical power at the transmitter is -12 to -7 dBm and the receiver sensitivity is better than -21 dBm; the difference between the two is the available optical power margin, used to compensate for the attenuation of the optical cable itself and the losses at splice points an

Question 4

What interfaces does the 2-channel video optical multiplexer provide, and what devices can it connect to?

Accepted Answer

The IDM-VDA2000 series 2-channel video optical multiplexer provides four types of service interfaces: the video port is of the BNC type with an input impedance of 75 Ω (unbalanced), the transmitter connects to the camera video output and the receiver connects to a DVR, NVR or monitor; the data port is of the RJ-45 type and supports RS-232, RS422 (4-wire) and RS485 (2-wire), and can connect to PTZ control, alarm collection and sensor acquisition devices; the audio port is an RJ45 connector provid

Question 5

What kind of device is the 2-channel video optical multiplexer, and what scenarios is it mainly used in?

Accepted Answer

The IDM-VDA2000 series 2-channel video optical multiplexer is an optical fiber transmission access device between surveillance sites and the surveillance center. Its transmitter and receiver are used in pairs for point-to-point networking, aggregating the two unidirectional video channels at the front end, together with on-site data, audio and Ethernet services, onto a single optical fiber for synchronous transmission. Traditional surveillance sites use coaxial cable to transmit video; when the

Question 6

What interfaces does the 4-channel video optical multiplexer provide, and what devices can it connect to?

Accepted Answer

The video side of the IDM-VDA4200 series 4-channel video optical multiplexer uses BNC interfaces for input and output, with an impedance of 75 Ω (unbalanced), and can be directly connected to cameras, DVRs, NVRs and monitors; the data port is an RJ-45 connector supporting RS-232, RS422 (4-wire) and RS485 (2-wire), and can connect to devices for PTZ control and alarm collection; the high-fidelity audio port is an RJ45 connector; the Ethernet port is an RJ-45 connector with 10M/100M adaptive opera

Question 7

What type of optical port does a 4-channel video optical multiplexer use, and how far can it transmit?

Accepted Answer

The optical interface of the IDM-VDA4200 series 4-channel video optical multiplexer is a standard FC type and can be customized to interfaces such as SC; the optical fiber is single-mode by default with multimode optional. The standard configuration of the device provides a transmission distance of 20 km; the transmit optical power at the transmitter is -12 to -7 dBm and the receiver sensitivity is better than -21 dBm (1310 nm). The difference between the two is the available link optical power

Question 8

What are the optical port type and transmission distance of an 8-channel video optical multiplexer, and what should be done if the distance is exceeded?

Accepted Answer

The transmitter receive/transmit rate of the IDM-VDA8200 8-channel video optical multiplexer is 1.25G bps with receive/transmit wavelengths of 1550 nm/1310 nm, and the receiver receive/transmit rate is likewise 1.25G bps with receive/transmit wavelengths of 1310 nm/1550 nm. The receive and transmit wavelengths at the two ends are exactly opposite, which allows bidirectional transmission of video, data, audio and Ethernet services over the same optical fiber without mutual interference. To determ

Question 9

How does an all-digital uncompressed video optical multiplexer ensure picture quality?

Accepted Answer

The IDM-VDA4200 series 4-channel video optical multiplexer uses all-digital uncompressed video technology: the transmitter samples at an 8-bit sampling bit width over a 0 Hz–6.5 MHz video bandwidth and transmits the signal directly over the optical fiber without compression or encoding, and the receiver restores it without distortion to analog video. As a result, the video signal-to-noise ratio (SNR) is ≥70 dB (weighted), luminance non-linearity is <3%, differential phase (DP) is <0.7° and

Question 10

How does all-digital uncompressed video technology ensure the picture quality of 8 video channels?

Accepted Answer

After the video signal completes A/D sampling at the transmitter it is transmitted directly in digital form, and the receiver performs D/A conversion to restore it; the link contains no encoding or decoding stage and therefore introduces no picture quality loss or stream jitter caused by compression algorithms. The video signal-to-noise ratio (SNR) of the IDM-VDA8200 8-channel video optical multiplexer is ≥70 dB (weighted), its luminance non-linearity is <3%, its differential gain (DG) is &lt

Question 11

A single E1 link carries only 2.048Mbps, so how can it transmit telephone and serial port data at the same time?

Accepted Answer

The IDM MINI8 uses the PCM30/32 frame structure to divide the 2.048Mbps E1 channel into 32 time slots (TS): 30 of these time slots carry 64 kbit/s services, and the remaining time slots are used for frame alignment and channel-associated signaling (CAS). Voice services are first encoded into 64Kbps digital signals using A-law in ITU-T G.711 and then occupy one 64K time slot; RS232/RS422/RS485 serial port data runs at a lower rate and can be multiplexed onto low-speed time slots in the same E1. T

Question 12

How Is E1 Time-Slot Non-Blocking Cross-Connection Implemented?

Accepted Answer

The key to non-blocking cross-connection lies in the cross-connect granularity and the matrix resources: the IDM DXC5200 uses the 64K time slot as the cross-connect granularity and establishes an independent connection relationship for each of the 32 time slots in every frame, so any input time slot can be connected to any output time slot, and adding or adjusting a circuit will not block services due to a matrix conflict. A PCM30/32 frame carries 32 time slots, 30 of which carry 64K services, T

Question 13

What is an E1 line? What are the core knowledge points?

Accepted Answer

E1 Basics　　Frame Structure of the E1 Channel　　In an E1 channel, 8 bits form one timeslot (TS), 32 timeslots form one frame (F), and 16 frames form one multiframe (MF). Within a frame, TS0 is primarily used to carry the frame alignment signal (FAS), CRC-4 (cyclic redundancy check), and remote alarm indication. TS16 mainly carries channel-associated signaling (CAS), the multiframe alignment signal, and the multiframe remote alarm indication. TS1 to TS15 and TS17 to TS31, a total of 30 timeslots, c

Question 14

What is the working principle of the Ethernet switch board?

Accepted Answer

Raytrans Digital Technology Co., Ltd. has launched an Ethernet switch board on the IDM MSTP155-24 platform, which is based on the Spanning Tree Protocol and the Unidirectional Link Protocol. It enables Ethernet switching and achieves ring network protection even under unidirectional link conditions, effectively overcoming the issues in Ethernet ring network protection when a single-direction fiber break occurs in an SDH ring network.The idea behind the Spanning Tree Protocol (STP) topology is th

Question 15

What are the characteristics of optical fiber?

Accepted Answer

Optical fiber is now one of the primary media for data transmission in our daily life and work, and it is indispensable to the development of the Internet. Next, let me walk you through the main characteristics and transmission principles of optical fiber.
Optical fiber transmission offers advantages such as low attenuation, wide frequency bandwidth, strong anti-interference capability, high security, small size, and light weight, giving it incomparable advantages in long-distance transmission a

Question 16

What are the three common types of fiber optic connectors?

Accepted Answer

LC Connector: The LC connector was developed by the renowned Bell Research Institute, utilizing a modular jack (RJ) latch mechanism for easy operation. The dimensions of its ferrule and sleeve are half the size of those used in standard SC and FC connectors, measuring 1.25mm. This allows for increased connector density in optical distribution frames. Currently, LC-type connectors have established a dominant position in single-mode SFF applications, and their use in multimode applications is als

Question 17

What are the common fiber optic connector types?

Accepted Answer

[Fiber Optic Connector Types:](
FC round with threaded coupling, ST bayonet-style round, SC bayonet-style square, LC similar to SC but half the size, PC micro-spherical polished, APC angled at 8° with micro-spherical polishing, MRTJ square, one end with dual-fiber transceiver integrated (mostly used on 3com), fiber optic modules: generally support hot-swapping, GBIC mostly uses SC or ST fiber interfaces, SFP small form-factor GBIC, uses LC type fiber. Single-mode: L, wavelength 1310; single-mode

Question 18

What Is Optical Fiber? What Are Its Application Scenarios?

Accepted Answer

Optical fiber, short for optical waveguide fiber, is a light transmission tool that utilizes the principle of total internal reflection of light within a fiber made of glass or plastic. The optical waveguide fiber was invented by Charles Kao, former president of The Chinese University of Hong Kong.　　The fine optical fiber is enclosed in a plastic sheath, allowing it to bend without breaking. Typically, a transmitting device at one end of the fiber uses a light emitting diode (LED) or a laser bea

Question 19

What are the characteristics and principles of fiber-optic transmission?

Accepted Answer

I. Background of Optical Communication
In today's world, optical fiber communication has become the primary means of communication.
Fiber-optic transmission systems offer the following significant advantages: large capacity and long transmission distance. The theoretical bandwidth of optical fiber can reach 20000 GHz, and the repeaterless transmission distance can reach 50-80 km. Made of glass, it is immune to electromagnetic interference and provides high transmission quality, making it sui

Question 20

What Is the Function and Working Principle of a Fiber Switch?

Accepted Answer

Fiber switches provide the capability to cascade many switches into a large-scale Fabric. By connecting one or more ports of two switches, all ports connected to the switches can see a unique image of the network, and any node on this Fabric can communicate with any other node.
In essence, by cascading switches, it is possible to build a large, virtual switch with distributed advantages, and it can span very large distances. A Fabric built from multiple switches appears as a single Fabric compos

Question 21

What is the working principle and function of a media converter?

Accepted Answer

The rapid advancement of informatization has led to growing demand for multimedia communications such as data, voice, and video. Ethernet broadband access has been elevated to an increasingly important position, and the required capacity of communication networks continues to expand. As a result, optical fiber communication has been widely adopted due to its advantages of large information capacity, good confidentiality, light weight, small size, relay-free operation, and long transmission dista

Question 22

What is the difference between optical fiber and optical cable? What are the common optical fiber connectors?

Accepted Answer

Optical fiber is a medium that transmits information from one end to another. It is a glass or plastic fiber that serves as a transmission medium for the passage of information.
Generally, the terms "optical fiber" and "optical cable" are often confused. Most optical fibers must be covered by several layers of protective structure before use, and the covered cable is called an "optical cable." The protective structure on the outer layer of the optical fiber prevents

Question 23

What are the applications and features of GPON?

Accepted Answer

GPON ApplicationsGPON-related terminal products are largely similar to EPON, with three main application scenarios:(1) FTTH/FTTO-type terminals targeting high-end and commercial users, generally referred to as SFU/SBU-type ONUs. The downstream PON fiber passes through a splitter and connects directly to the user's ONU, with one ONU serving a single user. User data services are uplinked via FE or GE ports, offering high security but at a higher cost, typically for premium and business users.(

Question 24

Top 10 Common FAQs About Optical Terminals

Accepted Answer

What is the main purpose of an optical terminal, and what is its current market price?     Simply put, an optical terminal is a type of optical communication device primarily used to transmit optical signals.     The market price of an optical terminal cannot be quoted arbitrarily. On the market, optical terminal equipment ranges from a few thousand yuan to tens of thousands, or even hundreds of thousands of yuan. Moreover, optical terminals are always us

Question 25

What Are Common Optical Terminal Faults and How to Troubleshoot Them?

Accepted Answer

Understanding Common Optical Terminal Faults at a Glance — Easily Avoid O&M Pitfalls
In scenarios such as security surveillance, power communications, and rail transit, the optical terminal serves as the core device for signal transmission, acting like a "bridge" in the entire communication link, carrying the stable transmission of video, audio, and data signals. Its normal operation directly determines the communication quality and reliability of the entire system. However, during

Question 26

What Does an Optical Terminal Do?

Accepted Answer

The function of an optical terminal: it is primarily a device that converts multiple E1 (a data transmission standard for trunk lines, typically at a rate of 2.048Mbps, adopted in China and Europe) signals into optical signals for transmission (its main role is to achieve electrical-to-optical and optical-to-electrical conversion). The price of an optical terminal varies depending on the number of E1 ports it supports. Generally, the smallest optical terminal can transmit 4 E1 lines, while the l

Question 27

What are the common issues in optical terminal installation and construction?

Accepted Answer

As the fiber optic market continues to mature, the application fields of optical terminals have become increasingly extensive. Moreover, their cost is basically on par with that of cable, and in some cases even lower, making fiber optic transmission increasingly advantageous.
  Analog Optical Terminal Series
  The following scenarios use a one-channel video and one-channel reverse data optical terminal as an example; other models operate on the same principle.

No video image and unable to contr

Question 28

What are the key points for routine maintenance of optical terminals?

Accepted Answer

As the application fields of optical terminals continue to expand, how to maintain and service video optical terminal equipment has become the most concerned issue for maintenance personnel. Based on its R&D experience in optical terminal equipment and after-sales service technology, Raytrans has summarized several key points for optical terminal maintenance.
Power Supply and Installation Environment of Optical Terminals
Power supply is the primary consideration for ensuring the reliability

Question 29

What indicators should be considered when selecting an optical terminal?

Accepted Answer

Indicators for Optical Terminal SelectionI. Optical Terminal Type: Analog Optical Terminal/[Digital Optical Terminal]( Single-mode/Multi-modeII. Transmission Distance: Fiber cable length/Fiber cable link loss (very important)III. Video:　　Number of video channels: 1/2/4/8/16/32/48　　Connection method: Direct connection/Video distributor/Video splitter/Character overlay/Others　　Display method: Monitor/Large screen/TV/OthersIV. Data:　　Number of data channels: 1/2/3/4　　Data type: RS232/RS485/RS422/TT

Question 30

What is the role of an optical terminal in a surveillance system?

Accepted Answer

An optical terminal is a transmission device in an optical communication system, primarily performing optical-electrical conversion and transmission functions. It is generally used in telecommunications, power, surveillance, industrial control, video transmission, and other applications, with wide-ranging use across various industries. The commonly referred to optical terminal is the one used in surveillance systems to transmit integrated information such as video, data, Ethernet, and audio. It

Question 31

What is the difference between an Optical Terminal and a Media Converter?

Accepted Answer

Optical Terminal is a device that converts multiple E1 (a data transmission standard for trunk lines, typically at a rate of 2.048Mbps, adopted in China and Europe) signals into optical signals for transmission. The price of an Optical Terminal varies depending on the number of E1 ports it supports. Generally, the smallest Optical Terminal can transmit 4 E1 channels, while the largest currently available can transmit 4032 E1 channels.
   Media Converter has one end connected to the opt

Question 32

What are the technical advantages of OTN and PTN respectively?

Accepted Answer

Technical Advantages of OTN and PTN
(1) Technical Advantages of OTN
The advantage of OTN lies in its proficiency in addressing ultra-long-distance, ultra-large-bandwidth transmission issues for IP services, providing transmission channels for a large number of large-granularity services such as 2.5 Gbit/s, 10 Gbit/s, and even 40 Gbit/s, which is difficult for PTN to achieve. However, OTN bandwidth allocation is also rigid, resulting in low bandwidth utilization and difficulty in handling smaller

Question 33

What Is the Definition of Packet Switching Technology?

Accepted Answer

Packet switching technology emerged when computer technology had developed to a certain level, and beyond direct voice communication via telephone, packet switching adds a packet header to each packet to indicate the destination address to which the packet is sent. The switch then forwards each packet to its destination based on the address flag in the packet header. This process is called packet switching.
A communication network that performs packet switching is called a packet-switched networ

Question 34

What is the definition and purpose of a patch panel?

Accepted Answer

A patch panel is the most important component in the administration subsystem, serving as the hub for cross-connecting the vertical backbone and horizontal cabling subsystems. Patch panels are typically installed in racks or on walls. With mounting accessories, patch panels can fully accommodate the needs of UTP, STP, coaxial cable, fiber optic, audio, and video. In network engineering, commonly used patch panels include twisted-pair patch panels and fiber optic patch panels.
Twisted-pair patch

Question 35

What are the common problems of PCM equipment in enterprise applications?

Accepted Answer

At present, PCM equipment has become basically ubiquitous in enterprise network applications. For PCM equipment, establishing a comprehensive, economical, reliable, and effective communication network that not only meets the current demands of voice, data, and video services in power systems, but also looks to the future by supporting an increasing number of user interfaces and larger capacity, is the key. However, will PCM applications within enterprise networks go smoothly?
Four major problems

Question 36

What is the working principle of Pulse Code Modulation (PCM)?

Accepted Answer

Working Principle
Pulse Code Modulation is the process of converting a time-continuous, amplitude-continuous analog signal into a time-discrete, amplitude-discrete digital signal for transmission over a channel. PCM involves first sampling the analog signal, then quantizing and encoding the sampled amplitude values.   Sampling is the periodic scanning of an analog signal, converting a time-continuous signal into a time-discrete signal. The sampled analog signal must still contain all the informa

Question 37

PCM30 Working Principle: What Is PCM30/32

Accepted Answer

PCM30 Equipment Working Principle
The 30-channel PCM equipment refers to equipment that provides 30 user interfaces and can directly provide 30 terminal service interfaces over a standard PCM30 primary group, i.e., a 2M transmission channel.
Optical Transmitter Composition
The electrical signal sent from the PCM equipment is a code type suitable for PCM transmission, either HDB3 code or CMI code. After the signal enters the optical transmitter, it first enters the input interface circuit for cha

Question 38

What is the difference between PDH and SDH?

Accepted Answer

I. PDH   PDH is the Plesiochronous Digital Hierarchy, which is divided into the European standard and the American/Japanese standard.   The European standard uses 2M as the base group, 8M as the second-order group, 34M as the third-order group, and so on.   The American/Japanese standard uses 1.5M as the base group, 6.3M as the second-order group, 32M as the third-order group, and so on.   The European standard is the internationally accepted standard, and China adopts this standard.   II. SDH

Question 39

14 Common FAQs About Telephone Optical Terminals

Accepted Answer

How to evaluate the performance of a telephone optical terminal  
How many optical ports and optical directions it has.  
How many E1 channels it provides.  
Whether it has an Ethernet interface.  
Whether it has a V.35 interface.  
Whether it has a V.11/V.24 interface.  
Whether it has an order wire telephone.  
Whether it has network management.  
Networking mode: whether it can form a self-healing ring.

Number of optical ports 1: Point-to-point modeThe cheapest telephone optical terminal h

Question 40

How to Troubleshoot Common Faults of Telephone Optical Terminal?

Accepted Answer

Device cannot be powered on

Check whether the power cable is connected correctly.  
Check whether the voltage is within the allowable operating range of the device.  
Check whether the power is within the operating range.2M link failure  
First, check whether the interface impedance matches. Ensure that the impedance of the connected device is consistent with that of the device itself.  
Each E1 channel has an indicator light. A lit indicator means the corresponding E1 signal is lost; under n

Question 41

How to troubleshoot installation, maintenance, and common faults of Telephone Optical Terminal?

Accepted Answer

1. Equipment Installation
　　1.1 Precautions for Equipment Installation
【This series of equipment contains precision components. Please handle with care and avoid severe vibration to prevent affecting equipment performance. If you find any parts damaged or missing during transportation, please notify the company's after-sales service department, and we will resolve the issue promptly.】
　　★ Remove the unit and accessories from the packaging. Pay attention to the orientation of the packaging bo

Question 42

Top 10 Common Questions About Telephone Optical Terminals

Accepted Answer

Summary: Based on years of experience in the production and R&D of telephone optical terminals, Raytrans has summarized the top 10 common questions about telephone optical terminals and proposed solutions, providing assistance to industry peers in the selection and maintenance of telephone optical terminals. Please point out any inaccuracies.
I. Specifications of Telephone Optical Terminals     There are many specifications for telephone optical terminals, but none of the

Question 43

What are common relay faults and how to detect and handle them?

Accepted Answer

A relay is one of the most commonly used actuating elements in electronic equipment. It is an electronic control device that consists of a control system (also called the input circuit) and a controlled system (also called the output circuit). It is typically used in automatic control circuits, and is also used in communication equipment such as PCM devices. In essence, it is an "automatic switch" that uses a smaller current to control a larger current. Therefore, it plays roles such a

Question 44

What is the RS232 Interface Definition?

Accepted Answer

RS232 interface is formally known as the "technical standard for serial binary data exchange interface between Data Terminal Equipment (DTE) and Data Communications Equipment (DCE)."
The standard specifies a 25-pin DB25 connector, defining the signal content of each pin and the signal levels. With continuous equipment improvements, the DB9 connector emerged as a replacement for DB25, and now the RS232 interface is commonly referred to as DB9.
RS-232 is one of the mainstream serial comm

Question 45

What advantages do Raytrans brand telephone optical terminals offer?

Accepted Answer

Optical transmission interfaces: Supports PDH and SDH interfaces

PDH interfaces support 155M, 250M, 2.5G, and 5G rates;

SDH interfaces support 155M and 622M rates;

Number of telephone service interfaces: 2-300 telephone channels available, in different models;

Optical transmission interface types: FC, SC, and SFP interfaces available, with single optical port, dual optical ports with mutual backup, and dual optical port chain networking;

Optical transmission distance: 20KM, 40KM, 80KM, 1

Question 46

What are the features of SDH technology and MSTP products?

Accepted Answer

SDH Technology and MSTP Product Analysis
I. Development Directions of Next-Generation SDH Technology and Products<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
    Regarding the development direction of next-generation SDH technology and the R&D strategies for corresponding products, this is a research hotspot in the telecommunications field. Researchers from different manufacturers and technical backgrounds hold different und

Question 47

What is the difference between single-fiber and dual-fiber?

Accepted Answer

The biggest difference between single-fiber and dual-fiber optical terminals lies in the optical modules on their mainboards; everything else is essentially the same.
Single-fiber Optical Terminal: Transmit and receive data over a single fiber.
Dual-fiber Optical Terminal: Transmit and receive data over two separate fibers.
As the name implies, a single-fiber optical terminal can save half of the fiber cable resources, i.e., it enables data transmission and reception over one fiber core, making

Question 48

What Are Signaling System No. 1, Signaling System No. 7, and PRI Signaling?

Accepted Answer

Signaling can be classified by the signaling channel into:
    1. Channel Associated Signaling (CAS)
    2. Common Channel Signaling (CCS)
    Channel Associated Signaling (CAS):
    A signaling method in which signaling and voice are transmitted in the same voice channel. The CAS currently adopted in China is called the Chinese Signaling System No. 1.
    Common Channel Signaling (CCS):
    A signaling met

Question 49

What are common issues when using optical terminals in security surveillance?

Accepted Answer

Fiber optic technology is increasingly used in security surveillance projects to transmit images, audio, data, and other information. The key equipment in fiber optic transmission systems – the digital video optical terminal – has gained wide popularity among users.
I. Regarding Optical Link Issues:
In security surveillance projects, fiber optic cables are mostly laid by the users themselves, typically G652 single-mode fiber. Since the system coverage area is generally not large, the optical lin

Question 50

What is the working principle and function of a telephone switch?

Accepted Answer

Telephone Switch Principle
In fact, the basic principle of a telephone switch is quite simple: it is the concentration and switching of voice. The main task of a telephone switch is to establish connections for calls between users, which is basically divided into two major parts: the speech path equipment and the control equipment. The speech path equipment mainly includes various interface circuits (such as subscriber line interface circuits and trunk line interface circuits, etc.) and the swit

Question 51

What is a trunk line? What are its advantages and disadvantages?

Accepted Answer

A trunk line: a telephone line that connects a user's private branch exchange (PBX), key telephone system (including telephone connectors with switching functions), paging station, mobile telephone switch, etc., to the local exchange is called a trunk line.
Trunk line hunting means that a single number contains multiple lines. Users only need to publish one representative number externally, but multiple calls can come in simultaneously. Each user can determine the number of trunk lines to ap

Question 52

What Are the Functions and Advantages of Video Optical Terminals?

Accepted Answer

The function of a video optical terminal is to convert one or multiple channels of analog video signals into optical signals through various encoding methods for transmission over optical fiber media. Since the conversion process from video signals to optical signals involves both analog conversion and digital conversion technologies, video optical terminals are further divided into analog optical terminals and digital optical terminals. However, due to the limitations of analog [optical termina

Question 53

What is the difference between a Video Optical Terminal and a Network Video Server?

Accepted Answer

Composition and Function of Video Optical Terminal and Network Video Server
　An optical terminal is a device used to convert optical signals and electrical signals to and from each other, without any compression of the transmitted signal.　A network video server is a device used to digitize analog signals, compressing the digital signals.An optical terminal consists of an optical transmitter and an optical receiver. The optical transmitter accepts electrical signals and converts them into optical

Question 54

What Is the Definition of Communication?

Accepted Answer

Communication: the exchange and transmission of information between people, or between people and nature, through certain behaviors or media. In a broad sense, it refers to the accurate and secure transfer of information from one party to another, by any method and through any medium, between two or more parties who require the information, provided that this does not violate the will of either party.
Tong (通): unobstructed, able to pass through, able to reach; to understand, to be thoroughly cl

Question 55

What is E1? How to Use E1

Accepted Answer

What is E1　　The European 30-channel pulse code modulation PCM is abbreviated as E1, with a rate of 2.048Mbit/s. China adopts the European E1 standard.　　One time-division multiplexed frame of E1 (with a frame length of T=125us) is divided into 32 equal timeslots, numbered CH0CH31. Among them, timeslot CH0 is used for frame synchronization, timeslot CH16 is used to transmit signaling, and the remaining CH1CH15 and CH17~CH31, totaling 30 timeslots, are used for 30 voice channels. Each timeslot tran

Question 56

What is IPTV and Its Key Technologies

Accepted Answer

IPTV, or Interactive Network Television, is an innovative technology that utilizes broadband cable TV networks, integrating internet, multimedia, telecommunications, and other technologies to provide home users with a variety of interactive services, including digital television. Users can enjoy IPTV services at home in two ways: (1) via a computer, or (2) via a network set-top box plus a conventional television. It adapts well to the rapid development trends of today's networks and makes fu

Question 57

What is an Optical Terminal?

Accepted Answer

Many people are unfamiliar with the optical terminal, but in essence, it is a dedicated device for optical-electrical signal transmission, widely used in communications, security, and daily low-voltage scenarios. Many are unclear about the definition and practical functions of an optical terminal. Below is a plain and clear explanation of the principles, classification, and development applications of optical terminals.
An optical terminal consists of two parts: an optical transmitter and an opt

Question 58

What is Trunking Mobile Communication

Accepted Answer

Trunking mobile communication is a relatively economical and flexible mobile communication system developed in the 1970s. It represents an advanced stage of development of traditional private radio dispatch networks. Traditional private radio dispatch systems suffer from poor overall planning, mixed models and standards, numerous small networks with many base stations, narrow coverage, severe noise interference, and waste of frequency resources. Therefore, a new radio dispatch technology—trunkin

Question 59

What is WAP

Accepted Answer

WAP (Wireless Application Protocol) is an open global standard for communication between digital mobile phones, the Internet, or other personal digital assistants (PDAs), and computer applications. It consists of a series of protocols used to standardize wireless communication devices, enabling Internet access, including sending and receiving emails, and browsing pages on WAP websites, among other functions. WAP closely integrates mobile networks with the Internet and corporate LANs, providing a

Question 60

What is G/EPON dual-mode adaptation, and what does it mean for on-site deployment?

Accepted Answer

G/EPON dual-mode adaptation means that a single terminal can operate either as an EPON ONU or as a GPON ONU, with the device automatically matching the PON standard in use. EPON corresponds to IEEE 802.3ah and GPON corresponds to ITU-T G.984, and the two types of network follow different technical approaches on the central office OLT side. The value for a project is concentrated in three areas: existing EPON sites and newly built GPON private networks can share the same terminal model, reducing

Question 61

How does a half-duplex radio set access a full-duplex telephone network?

Accepted Answer

Devices such as trunking radio sets and radio sets only transmit while the push-to-talk button is held, so they originally could not intercommunicate with the full-duplex calls of a telephone network. The EMVOICE24 interface of the IDM MAP4E1-30 hardware voice conference device can directly connect devices such as radio sets, trunking intercoms and access control intercoms, and the optional voice-triggered communication activation function provided by the conference room brings half-duplex commu

Question 62

How does all-digital uncompressed video technology ensure picture quality?

Accepted Answer

The IDM-VDA2000 series 2-channel video optical multiplexer uses all-digital uncompressed video technology: at the transmitter the video signal is sampled with an 8-bit sampling bit width over a 0 Hz~6.5 MHz video bandwidth and transmitted directly over the optical fiber without compression or encoding, and at the receiver it is restored as an analog video output without distortion. The video signal-to-noise ratio (SNR) of the device reaches ≥70 dB (weighted), with a differential phase (DP) <0

Question 63

What interfaces does the IDM-30FNV4 multi-service optical multiplexer provide, and what devices can it connect to?

Accepted Answer

The IDM-30FNV4 multi-service optical multiplexer provides five types of interfaces by service type. The video side uses BNC interfaces with an impedance of 75 Ω (unbalanced) and connects to cameras and monitors; the optical side uses an FC interface that can be customized to the SC type, with single-mode transmission and the two ends used in pairs. The Ethernet side provides 2 groups of RJ-45 interfaces with 10M/100M adaptive operation, supporting IEEE802.3. The E1 side provides 8 groups of tran

Question 64

What interfaces does the IDM DXC5200 Integrated Service Cross-Connect Multiplexing Equipment provide, and what services can it access?

Accepted Answer

The interfaces of the IDM DXC5200 are divided into the line side and the service side. The E1 interface has a bit rate of 2.048 Mbit/s and HDB3 line coding, complies with ITU-T G.703, provides 75 Ω coaxial or 120 Ω balanced impedance, and uses the PCM30/32 frame structure. The audio interface covers 300 Hz~3400 Hz and is A-law companded in accordance with G.711 into 64 kbit/s voice channels, with a loop current of 20 mA per channel. Among the data interfaces, V.35 is provided in RJ-45 form at a

How Is 64K Time-Slot Cross-Connection Implemented Under the PCM30/32 Frame Structure?

How far can the IDM-MINI 20Km single-fiber PCM multiplexer transmit? How is the optical path calculated?