| «‹ July 2026 ›» | | S | M | T | W | T | F | S | | | | 1 | 2 | 3 | 4 | | 5 | 6 | 7 | 8 | 9 | 10 | 11 | | 12 | 13 | 14 | 15 | 16 | 17 | 18 | | 19 | 20 | 21 | 22 | 23 | 24 | 25 | | 26 | 27 | 28 | 29 | 30 | 31 | |
|
2013 年 8 月 1 日 星期四  |
| What are the Advantages and Disadvantages of Fiber Optic Cab |
分類: 未分類 |
Fiber optic cabling consists of strands of purified glass, or even plastic, rods that conduct specific wavelengths of light, analogous to the electrons carried along a Copper Cable. However, light traveling through glass or plastic is not susceptible to the same problems that metal conductors are; The electromagnetic radiation that results from current traveling through a wire is not present in optical conductors, and optical conductors can be made much smaller than metal ones.
Advantages of Fiber Optic Cabling
There are four advantages of fiber optic cabling, these advantages explain why fiber is becoming the preferred network cabling medium for high bandwidth, long-distance applications:
1. Immunity to Electromagnetic Interference (EMI)
All copper cable network media sharing a common problem: they are susceptible to electromagnetic interference (EMI), fiber optic cabling is immune to crosstalk because optical fiber does not conduct electricity and uses light signals in a glass fiber, rather than electrical signals along a metallic conductor to transmit data. So it cannot produce a magnetic field and thus is immune to EMI.
2. Higher Possible Data Rates
Because light is immune to interference, can be modulated at very high frequencies, and travels almost instantaneously to its destination, much higher data rates are possible with fiber optic cabling technologies than with traditional copper systems. Data rates far exceeding the gigabit per second (Gbps) range and higher are possible, and the latest IEEE standards body is working on 100Gbps fiber based applications over much longer distances than copper cabling. Multimode is preferred fiber optic type for 100-550 meters seen in LAN network, and since single mode fiber optic cables are capable of transmitting at these multi-gigabit data rates over very long distances, they are the preferred media for transcontinental and oceanic applications.
3. Longer Maximum Distances
Typical copper media data transmission by the distance limits the maximum length of less than 100 meters. Because they do not suffer from the electromagnetic interference problems of traditional copper cabling and because they do not use electrical signals that can dramatically reduce the long distance, single-mode fiber optic cables can span 75 kilometers (about 46.6 miles) without using signal-boosting repeaters.
4. Better Security
The Copper cable transmission media is susceptible to eavesdropping through taps. A tap (short for wiretap) is a device that punctures through the outer jacket of a copper cable and touches the inner conductor. The tap intercepts signals sent on a LAN and sends them to another (unwanted) location. Electromagnetic (EM) taps are similar devices, but rather than puncturing the cable,they use the cable’s magnetic fields, which are similar to the pattern of electrical signals. Because fiber optic cabling uses light instead of electrical signals, it is immune to most types of eavesdropping. Traditional taps won’t work because any intrusion on the cable will cause the light to be blocked and the connection simply won’t function. EM taps won’t work because no magnetic field is generated. Because of its immunity to traditional eavesdropping tactics, fiber optic cabling is used in networks that must remain secure, such as government and research networks.
Disadvantages of Fiber Optic Cabling
With all of its advantages, many people use fiber optic cabling. However, fiber optic cabling does have a couple of disadvantages:
1. Higher Cost
The higher cost of fiber optic cabling has little to do with the cable these days. Increases in available Fiber Optic Cable manufacturing capacity have lowered cable prices to levels comparable to high end UTP on a per-foot basis, and the cables are no harder to pull. Ethernet hubs, switches, routers, NICs, and patch cords for UTP are very inexpensive. A high quality UTP-based 10/100/1000 auto-sensing Ethernet NIC for a PC can be purchased for less than $25. A fiber optic NIC for a PC costs at least four times as much. Similar price differences exist for hubs, routers, and switches. For an IT manager who has several hundred workstations to deploy and support, that translates to megabucks and keeps UTP a viable solution. The cost of network electronics keeps the total system cost of fiber-based networks higher than UTP, and ultimately, it is preventing a mass stampede to fiber-to-the-desk.
2. Installation
The other main disadvantage of fiber optic cabling is that it can be more difficult to install. Copper cable ends simply need a mechanical connection, and those connections don’t have to be perfect. Fiber optic cable can be much trickier to make connections for mainly because of the nature of the glass or plastic core of the fiber cable. When you cut or cleave (in fiber optic terms) the fiber, the unpolished end consists of an irregular finish of glass that diffuses the light signal and prevents it form guiding into the receiver correctly. The end of the fiber must be polished and a special polishing tools to make it perfectly flat so that the light will shine through correctly.
Figure shows the difference between a polished and an unpolished fiber-optic cable end
|
| 2013 年 7 月 31 日 星期三 |
| EMCORE Added Medallion 8000 to Its 1550nm CATV Fiber Optic T |
分類: 未分類 |
The leader of compound semiconductor-based components and subsystems for the fiber optics and space solar power markets added the Medallion 8000 to its 1550nm Directly-Modulated DWDM CATV transmitter.
This new design of the EMCORE's 1550nm CATV fiber transmitter serve for the applications which require both CATVE and Satellite-Intermediate Frequency (SAT-IF) singles to be transmitted over fiber lengths up to 30km. This dual-use capability of the transmitter supports network architecture which requires a single transmitter to carry multiple signals, while lowering costs, system complexity and rack space requirements.
The Mediallion 8000 supports 79-channel NTSC analog signals and/or a combination of QAM and SAT-IF signals with a reduced number of CATV analogy channels. It supports four fixed fiber length options - 0-10km, 5-15km, 10-20km, and 15-25km - with a maximum of 18 Dbm stimulated Brillouin Scattering (SBS) suppression. This product is also available with a selectable fiber length option.
The selectable fiber length option allows the user to set the Medallion 8000 for best optimized CSO (Composite Second Order) distortions at any fiber length from 0-30km in 1km increments and has a maximum SBS suppression of 20dBm.
The Medallion 8000 family of transmitter products is designed to support various CATV transmitter applications with a common platform. 75 ohm CATV RF video input supports frequencies up to 1002 MHz. Other design features include low chirp control. Noise suppression circuitry, and patented pre-distortion technology for high performance with EMCORE's range of cooled broadband directly modulated lasers. A second 75-ohm RF input supports frequencies up to 2700 Mhz for fiber-to-the-premises (FTTP), SAT-IF, and wireless applications.
Monitoring and configuration of the Medallion 8000 are supported by EMCORE's latest generation web GUI, Telnet, and Simple Network Management Protocol (SNMP) software via a front-panel display, RS-232 port, and Ethernet port. The Medallion platform is mechanically designed for flexibility and space efficiency including universal rack-mount features, modular front panel design for private label convenience, and optional front and rear port placement. Dual-redundant field-replaceable fans and power supplies are standard.
"The new Medallion 8000 directly modulated transmitter family builds on the strengths of our popular Medallion 6000 externally modulated series and augments our offering for concurrent transmission of CATV and SAT-IF signals over fiber," said Jaime Reloj, vice president of business development for EMCORE. "Network providers are demanding high-quality, economical delivery of video to their customers, while extending capacity and improving network management intelligence. The Medallion 8000 series transmitters are ideal for extending traditional hybrid fiber coaxial CATV systems, for RF overlay for FTTP, and for RFoG (RF over glass) projects in countries around the world."
|
| 2013 年 7 月 29 日 星期一 |
| Outstanding Cisco GBIC And SFP Transceivers |
分類: 未分類 |
GBIC transceiver is one of the many kinds of transceivers that is capable of receiving as well as sending data. The purpose of GBIC transceiver is to convert digital media between a separate fiber optic based network and Gigabit Ethernet network. From this one device, users are able to generate connections utilizing the multi or single mode fiber optic ports along with the copper wiring.
GBIC transceiver comes with multiple sources agreement, this enables the manufacturers to save their money to set up their own standards and also resolve any compatibility issues as well. With the help of a GBIC transceiver, Gigabit network devices can connect to the copper wires, single mode fiber ports, or any other multimode fiber ports directly. GBIC transceivers are appropriate for any interconnections over the Gigabit Ethernet hubs and for switches platform.
Various variants of GBIC transceivers are available and the latest SFP modules (or mini-GBIC) provide companies and service providers with the ability to set up a Fiber Channel and Gigabit Ethernet connection within their network with ease and simplicity. The Gigabit Interface Convertor is the standard for transceivers that gets plugged into Gigabit Ethernet and gets connected to a fiber optic network.
Usually the SFP modules are found with the LC fiber connecter interface. This model of transceiver covers a wide range including various types working at different wavelength and distance. This type of transceivers provide customers with a very convenient and affordable solution for finding a large area of habitat in metropolitan area access, data center, and ring networks, campus and storage area networks. Cisco which believes in their motto of meeting commitment and excellence offers a wide set of choices in regard of protocols, speeds, reaches and transmission media support. They provide customers with a larger range of interfaces which are detachable to multimode or single-mode type of optic fibers along with coaxial or UTP electrical cables. In addition to this transportation of LAN packets through TDM-based WAN and also streams over the packet-switching networks.
The main products from Cisco are switches, wireless systems; open networking systems, security systems, software, modules and interfaces, network management and automation system. Cisco is also specialized in producing transceivers which include a well advanced and useful type of SFP transceiver. Cisco has made enormous amount of investments spent to keep rhythm of standard of Cisco SFP. With high quality raw materials, skilled labor and advanced manufacturing equipment they facilitate highly efficient design for host devices, provide flexibility in network, and an immense amount of savings regarding the maintenance of the system.
The advantages of Cisco SFP and GBIC transceiver are its scalability that uses only one strand to move up to about eight channels. The equipment works with a standard SFP and GBIC port. In addition to that, the Cisco equipment does not require be powered and even configured. It is a versatile equipment that enables multiple network configurations. Simultaneously, these products help businesses and service providers to maximize the bandwidth of a Gigabit Ethernet without making use of a new fiber.
FiberStore Technology, offers not only original Cisco SFP modules and Cisco GBIC transceivers, but also compatiable SFP and GBIC modules. Have a wide selection there. |
| 2013 年 7 月 26 日 星期五 |
| The Campus Cabling System Solutions |
分類: 未分類 |
Introduction
With the spread of computer applications, along with the rapid development of network technology, the campus network has become an essential school information infrastructure. The implementation of the campus network, for schools to adapt to new developments and make fuller use of existing teaching resources for teching, management has provided a guarantee. Construction of intelligent building network as the physical basis. Using a variety of transmission media of the communication management device and the terminal connected. Its performance can affect the normal operation of the network and the length of life. Therefore, the design of a scientific and rational, optimized campus cabling system is to further play a variety of network equipment functions, the information and communication technologies to achieve the school a good development, improve the level of application management key.
The Campus Cabling System Overview
According to GB/T 50314 "Intelligent Building Design Standards" about the demarcation of ten categories of building regulations, school buildings, including ordinary full-time colleges and universities, high schools and senior vocational schools, junior and primary schools, nurseries and kindergartens school buildings, etc. Different levels of the school, its size, environment, personnel are different, so the campus cabling system requirements will be different.
The Campus Cabling System Features
In China, a full time ordinary institutions of higher learning, the campus area (not including campuses district), in general, nearly acres, some even a few acres. Distribution of number of buildings on campus and many species has a teaching building, comprehensive building, laboratory buildings, art building (including the campus theater, dance halls on campus, campus cultural centers), libraries, teachers' apartments, student apartments, gymnasium, conference centers, schools' hospitals, canteens and so on. Their application also includes teaching, testing, physical, network, accommodation, living, health care and other aspects. For colleges and universities this area, building scattered places different functions in the design of cabling, to be able to meet all of these different buildings, different application requirements, we need the entire cabling system to conduct a comprehensive in depth design considerations.
Figure 1: Campus network design
On campus cabling system, according to the classification of schools located in differnet, differnet mission, teaching different functions, as well as regional and other characteristics of different regions, each school has a different more or less cabling place. However, there are several points which can be used as colleges campus cabling system to explore the commonalities, but also can be used as a variety of colleges and universities can learn from campus cabling system solutions.
1. Campus Cabling diversity
a. Building diversity
We also mentioned earlier, in the campus, especially college a wide variety of buildings, each building its building types and architectural features may vary. Some twenty or thirty or more layers of tall buildings (such as the school's main building, complex building, etc.), while others are one, two dwarf room (such as canteens, etc.); Some large bay, less information building (such as school gymnasium, etc.); While others are small spaces, intensive information construction (such as multimedia classrooms or computer training room, etc.). For such floor height varies, of various sizes, the number of different information points, we have to make different plans. For high rise buildings, for the convenience and savings trunk cable laying wires, equipment room locationi will need to be carefully considered, such as computer room location is set to the middle of the building. And you do not need low building special consideration. For information point-intensive construction, telecommunications room on each floor of its location also needs attention. Because if you set reasonable, we can save a lot of horizontal cable; What's more, if too much information points in the same layer, also need to consider setting up multiple telecommunications rooms. For large bays place, not only to consider the distribution of information points, but also consider wheter there is the level of information points length over 90 meters, if there are more than 90 meters of the situation, we need to consider the use of fiber optic cable or increase between telecommunications solutions. Also, in some campus gymnasium, auditorium and other places, also need to consider whether to set CP boxes and other issues.
b. Application of diversity
In colleges and universities, the diversity of buildings, each building determines the variety of applications. Such as teachers' apartments, student dormitories, school comprehensive building, administration building, a variety of different teaching building, laboratory building used for research, data storage and computing centers. Applications and their information needs are very different. So many applications need not buildings and places, they must be designed according to different requirements. Teachers apartments, student dormitories according to ordinary residential buildings can be cabling design; househole classroom or every student dormitory apartment, basically meet a data point, a voice can be. Comprehensive building, administration building can be carried out according to the way commercial office planning and design; In addition to meet the demand of each office's basic data, voice, consider increasing the internal campus network information in a specific department, such as education private network information point requirements. A variety of conferentce rooms, reception and other areas, need to consider adding wireless AP points. Data storage and computing centers can be designed according to the data center, to meet a variety of information throughout the campus switching, aggregation and storage. The experimental and research laboratory building as an important place, which may have strong radiation, corrosive material existence, there may exist high temperature, humidity, shock and vibration environments, there may be the most dangerous biological virus. Therefore, their application and requirements may be much more than we usually say ten categories of construction areas, so for special programs. To take into account not only the electromagnetic interference, environmental impact, but also consider the potential life safety issues. Therefore, these sites suggest using the whole screen or fiber class industrial grade high flame retardant wiring products, such as using fire-retardant grade reach CMP / OFNP grade, industrial grade reaches IP67 cabling products.
2. High-speed transmission of information
High speed transmission of information for campus cabling system is already a pressing task. A variety of multimedia transmission, video transmission and other large flow of data communication more and more. For school on the high speed network transmission channel is essential. Including multimedia educational system, remote network education system, digital libraries, data centers and other places, is information is very concentrated, at least to ensure Gigabit to the desktop, Gigabit backbone. Under the condition of the budget allows, it is best able to do Gigabit to the desktop, 40G/100G as the backbone for future development needs. For classroom apartment or student residence, it should try to make Gigabit to the desktop requirements. Because who knows, in the next 5-10 years, or longer period of time, how fast development of the Internet? telematics what would happen to the great changes? Campus Network what will change? So in product planning, to do not only meet the existing information and communication needs, but also to do with a certain forward looking.
3. Stability and security of information
In the campus network, the reliability and security of information transmission is very important, because it not only directly related to the use of campus communications network, but also to the entire campus of internal and external education system problems. Which may affect the security of network communications to the national education system. Instability in the event of information or information leaks, not only caused the affected education, and may bring significant social problems. Such as school entrance examination system due to system instability problems, or important information or test data within the education sector was stolen during transmission and so on. So campus intranet for information requirement is in any case have to ensure that the information transmitted high reliability, high security. In the planning and design of the campus cabling must be to choose a good quality cabling products, but also in fiber optic cabling system to avoid interference or disclosure of information. Achieve stable performance, reliable transmission of information security.
The Campus Cabling System Considerations
1. Disaster preparedness
Disaster prevention, for any cabling system is need, and also is necessary. On campus cabling system, pay attention to disaster prevention and many, such as earthquakes, lightning, flood, fire, etc. Around the school to the actual situation may have different, but in the integrated wiring system, the following two disasters have a very important relationship.
a. Lightning Stroke
Campus cabling system is different from general cabling system is one of the local architecture is numerous, wide distribution. Each building and interconnection of information between, or the information architecture and data center interconnection, must pass a variety of outdoor communication cables, so the campus backbone cable corresponding increase, which gives the outdoor cabling lightning protection challenges. Because once a root trunk cable struck by lightning, and the grounding system in case of a problem or did not do, when hundreds of thousands of volts high voltage transient will pass along the cables between devices, resulting in equipment damage, data lost, resulting in significant losses. So into the line of good grounding system and surge protection is very important. Of course, if you want to achieve more secure, avoid outdoor cables in danger of being struck by lightning can also be used outdoors in all non-metallic reinforcing outdoor fiber optic cable.
b. Fire Disaster
In addition to natural disasters, the current fire casualties and property loss is caused by the most serious disasters. On campus, most of the buildings are crowded places. In addition to selecting a variety of fire related materials and good fire prevention measures, cabling system cables fire retardant also has become essential. Because as the demand for information transmission, communications cable in the building has more than the number of number of strong electric cables trend, but the communication cable fire retardant has not been given due attention.
In addition, for campus cabling system, others, such as the computer room of the need to guard against seismic reinforcement, cables rat bite, etc., also need to pay attention.
2. Management
For school cabling systems, too much applications, and wide distribution of information points, application and needs vary, which brought the system management and maintenance of a great test. The traditional label drawing and handwriting management, or use the computer for documentation and preservation of the way, for such a large cabling systems, it has become beyond their grasp. In particular, to achieve a change to the information point and preservation of records in a timely manner, it is very difficult. Therefore, within the scope of the budget allows, it is recommended universities such as large scale cabling system uses intelligent infrastructure management system to improve cabling system maintenance and management, and enhance network security.
3. Intelligent Building digitized
In campus intelligent cabling, in addition to our previously mentioned, but also includes the campus radio systems, fire alarm systems, electronic fence system, monitoring system, LED large screen display systems, etc. These systems are in the transition to digital. Because of a digital campus will be teaching, research, management, technical services, services life and campus information collection, processing, integration, storage, transmission and application, so that the use of digital resources are fully optimized. By implementing from the environment (including equipment, classrooms, etc.), resources (such as books, handouts, courseware, etc.) to the application (including teaching, learning, management, service, office, etc.) all digitized, in the traditional campus built on a digital space to improve the operating efficiency of the traditional campus, expanding the traditional campus business functions, and ultimately the overall educational process information, so as to improve the management level and efficiency. Therefore, the campus all variety of intelligent system based on transmission channel will also jumped to Gigabit, and even Gigabit network requirements. In the design and planning, and perhaps to consider the application of digitization. In which the product can be selected copper Category 6 Products, cat 6a, cat 7 products, fiber optic cable in OM3 OM4 multimode cable and other fiber optic products. However, for fire alarm systems, campus broadcasting system, and its products should be chosen to meet the high flame retardant properties, if possible, it is best to choose a high fire retardant cables. Because it does not lead to a fire occurs due to the rapid combustion of the cable causes the system to malfunction.
Figure 2: 305m Bulk Cat6 550MHz Cable UTP
Conclusion
Campus cabling system though complex, but as long as we grasp the core features of cabling system, clear the standard cabling system the basic requirements, specifically the various buildings, the application of the various systems and functions. It is not difficult to design and planning. Even the school have dozens, hundreds buildings, even if there are many school of information and communication applications, the final analysis are inseparable from the basic principles of cabling. Therefore, cabling system in the school, in order to maximize long as we grasp little less to more of the principles from the point to the line, from a line to a plane unfold. You will find, and then a big projects, the final show in front of us or our common and often do a single type of building cabling system, just follow their individual needs and applications for planning and design, you can complete set of perfect school cabling system.
|
| 2013 年 7 月 25 日 星期四 |
| Plastic Optical Fiber Is Considered To Use In FTTH Applicati |
分類: 未分類 |
The cost of plastic optical fiber cable (POF) in high-speed short-distance communication transmission is as same as symmetrical cables, the transmission bandwidth up to several GHz within 100 meters, and with easy connection, good flexibility, easy bending and other advantages. Despite the current system performance is still in the early stage of research or application, but it is not to be ignored of its roles in the future short distance communication, from the advantage of price and performance, making it has a broad prospect in the whole fiber optic network of FTTH application.
Compared with quartz fiber, POF has the following advantages: low modulus, large core diameter (0.3-1.0mm), can use simple POF connectors when splicing, even if the 30μm deviation produced by optical fiber splicing centre alignment does not affect the coupling loss; large numerical aperture (about NA0.5), the acceptance light angle up to 60°and that of quartz fiber is only 16 °, availability of cheap LED, and high coupling efficiency;flexibility is good, easy to manufacture and use; a low loss window in the range of visible light; light weight; low cost and processing cost.
Compared with other transmission mediums in the LAN(Local Area Network) system, POF network also has obvious advantages: POF is not sensitive to electromagnetic interference, no radiation, attenuation constant in different data rates, error rate can be forecasted, can be used in electrical noisy environment; features long-size, can reduce the requirement of tolerance control in joint design, so lower the cost of net.
Plastic optical fiber as the ideal transmission medium for short-distance communication network, plays an important role in the data transmission of future intelligent household, office automation, industrial control network, the airborne communication network, military communication network.
Through the plastic optical fiber, we can realize the networking of intelligent home appliances (home PC, HDTV, telephone, digital imaging equipment, security equipment, air conditioning, household refrigerators, sound system, kitchen appliances, etc.), getting home automation and remote control management, improving living quality. Through the plastic optical fiber, we also can realize the office equipment networking, for example, computer networking can realize the computer parallel processing, can greatly improve the working efficiency of high-speed data transmission between the office equipments, realizing telecommuting and so on.
When the data rate is less than 100Mbps of low speed LAN, SI plastic optical fiber can realize the transmission within 100 meters and small numerical aperture POF can achieve the transmission in 150Mbps50m.
At present, POF is also widely used in the manufacturing industry. Through the converter, POF can be connected with RS232 converter, RS422 converter, 100Mbps Ethernet, token ring and other standard protocol interfaces, thus providing stable, reliable communication lines in harsh industrial manufacturing environments. POF enables high-speed transmission of industrial control signals and instructions, avoiding the risk of communication interrupt resulted by electromagnetic interference with metal cable lines.
POF is lightweight and durable, can form a network of on-board unit communication network and control system, the micro-computer, satellite navigation devices, mobile phones, fax and other peripherals into the overall design of locomotives, passengers can also enjoy music, movies, video games, shopping, Internet and other services in the seat through the plastic optical fiber network.
In military communication, POF is being developed for high-speed transmission of large amounts of the third and confidential information, for example, using the POF characteristics of light weight, flexibility, quick connection, suitable for portable wear, for soldiers wearable light computer systems, as well as can be inserted into the communication network to download, store, send and receive mission critical information, and displayed on the helmet display.
With the development of POF manufacturing technology and raw material preparation technology, the production cost of POF will continuously reduce; from the current development situation of laser, optoelectronic integrated device and connector, with the continuous expansion of production scale, we believe that the cost of sending and receiving devices will decline significantly, so the POF has more advantage in access communication. |
« | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | ... | 37 | »
|
