2019年6月16日星期日

Difference bewteen Transceiver and Transmitter

A transmitter can either be a separate piece of electronic equipment or an integrated circuit (IC) within another electronic device. A transmitter generates a radio frequency current applied to the antenna, which in turn radiates radio waves for communication, radar and navigational purposes. The information that is provided to the transmitter is in the form of an electronic signal. This includes audio from a microphone, video from a TV camera, or a digital signal for wireless networking devices. The electronics for a transmitter are simple. They convert an incoming pulse (voltage) into a precise current pulse to drive the source. Different transmitter has different functions. Take the optical transmitter as an example, it consists of the following components: optical source, electrical pulse generator and optical modulator. And the role of it is to convert the electrical signal into optical form, and launch the resulting optical signal into the optical fiber.
 
A transceiver is a device made up of both a receiver and transmitter (the name “transceiver” is actually short for transmitter-receiver) and these two gadgets are in a single module. When no circuitry is common between transmit and receive functions, the device is a transmitter-receiver.
 
Transceivers can be found in radio technology, telephony as well as Ethernet in which transceivers are called Medium Attachment Units (MAUs) in IEEE 802.3 documents and were widely used in 10BASE2 and 10BASE5 Ethernet networks. Fiber-optic gigabit, 10 Gigabit Ethernet, 40 Gigabit Ethernet, and 100 Gigabit Ethernet utilize transceivers known as GBIC, SFP, SFP+, QSFP, XFP, XAUI, CXP, and CFP, among which Cisco SFP is the most popular one. In addition, 1000BASE-T SFP, 10GBASE-T SFP+ and 1000BASE-T copper SFP we mentioned before are all transceivers.
 
Transceiver vs Transmitter
From the above information, we can know that the transmitter can only be used to transmit signals, while the transceiver can both transmit and receive signals. However, many view transceivers as a compromise in terms of performance, functionality, portability and flexibility and if they had any practical value it would be in mobile and portable applications. Transceivers sacrificed some features and performance to gain the smaller size/weight and cost.
 
As for the portability, a transceiver just needs the space of one module, but functions as two different modules. It is easy to be taken on the go. Separate transmitter is not as convenient in some circumstances as it is probably heavier, and takes up more room. But they are advantageous because each could benefit from its own design, without compromising in areas such as I-F frequency choice, conversion frequencies, and audio stages and they are easier to build and work on.
 
As far as the price is concerned, in most cases, a separate transmitter consumes more power. And the price of a single transceiver is much lower than that of a transmitter plus a receiver.Using a common frequency generation/tuning scheme, power supply and other components, it costs less to manufacture a transceiver than a separate transmitter and receiver.As to how to choose from them, the answer depends on your application.
 
Conclusion
You may find many transmitters in you life, like the TV remote control. Although transceiver is not commonly noticed around you, it is actually commonly applied to many places. We can say that it is invisible but versatile. I sincerely hope that this article will help you understand the difference: transceiver vs transmitter, only then, can you use them in the right way.

Fiber Splice Tray and Fiber Enclosure

In the cabinet, we may find many devices and gadgets, such as fiber patch panel, fiber splice tray, fiber enclosure, adapter panel and zip ties which are all little but critical components for cable management. Fiber patch panel, the one we have cued for a lot of times, will give way to fiber splice tray and fiber enclosure, the two subjects that we will introduce today.
 
Fiber Splice Tray Unveil
As we all know, it is usually unavoidable to match splice fiber optic cables with fiber pigtails in data center, which not only demands lower space requirement but also allows a better network performance compared with other fiber optic termination methods.
 
Fiber splice tray, very popular in data center and server room, is a plate to store the fiber cables and splices and prevent them from becoming damaged or being misplaced. Splice trays are necessary for holding and protecting individual fusion splices or mechanical splices. One of the important factors of fiber splice tray is the fiber count that it can hold. Most fiber splice tray can hold up to 24 fiber splices. 12-fiber splice trays are the most commonly used fiber splice tray in fiber optic network.
 
A Closer Look At Fiber Enclosure
It is a box that contains the devices to connect various fiber optic cables. Fiber enclosures can be classified into two configurations, namely rack mount fiber enclosure and wall mount fiber enclosure. And the rack mount fiber enclosure can be further categorized by its height and the design. We have 1U, 2U and 4U choices. The rack mount enclosures come in two flavors. One is the slide-out variety , and the other incorporates a removable lid which requires the user to remove the whole enclosure from the rack to gain internal access.
 
How The Two Coordinate?
Owning solely a fiber splice tray is far more enough. It should be equipped with a device to provide a safe and easy-to-manage environment for fiber splices. Apart from fiber optic splice closure, fiber distribution box and fiber optic enclosure, we can adopt the fiber enclosure displayed today. Fiber splice tray can be installed in fiber enclosure.
 
Here takes the example of fiber splice tray used in FHD fiber enclosure of FS.COM as shown in the following picture. It is a 96-fiber enclosure which has four 24-fiber adapter on the front panel. This 1U fiber enclosure can hold up four 24-fiber splice tray to provide the space for 96 fiber optic splices.
 
Conclusion
As optical fibers are sensitive to pulling, bending and crushing forces, fiber splice tray and fiber enclosure serve as double protections which are used to provide a safe routing and easy-to-manage environment for the fragile optical fiber splices. Attention! Bare fibers without protection tubes should never be exposed outside of a splice tray. It’s our pleasure to provide you with the best solutions.

Do you know Fiber Optical Transponders?

 
As we know, transponder is important in optical fiber communications, it is the element that sends and receives the optical signal from a fiber. A transponder is typically characterized by its data and the maximum distance the signal can travel.
 
Functions of a Fiber Optical Transponder includes:
 
Electrical and optical signals conversion
Serialzation and deserialization
Control and monitoring
Applications of Fiber Optical Transponder
 
Multi-rate, bidirectional fiber transponders convert short-reach 10gb/s and 40 gb/s optical signals to long-reach, single-mode dense wavelength division multiplexing (DWDM) optical interfaces.
 
The modules can be used to enable DWDM applications such as fiber relief, wavelength services, and Metro optical DWDM access overtay on existing optical infrastructure.
 
Supporting dense wavelength multiplexing schemes, fiber optic transponders can expand the useable bandwidth of a single optical fiber to over 300 Gb/s.
 
Transponders also provide a standard line interface for multiple protocols through replaceable 10G small form-factor pluggable (XFP) client-side optics.
 
The data rate and typical protocols transported include synchronous optical network/synchronous digital hierarchy (SONET/SDH) (OC-192 SR1), Gigabit Ethernet (10GBaseS and 10GBaseL), 10G Fibre Channel (10 GFC) and SONET G.709 forward error correction (FEC)(10.709 Gb/s).
 
Fiber optic transponder modules can also support 3R operation (reshape, retime, regenerate) at supported rates.
 
Often, fiber optic transponders are used to for testing interoperability and compatibility. Typical tests and measurements include litter performance, receiver sensitivity as a function of bit error rate (BER), and transmission performance based on path penalty.Some fiber optic transponders are also used to perform transmitter eye measurements.
 
fiber-mart.com Provides Optical Transponders Solution
 
Let’s image that the architecture that can not support automated reconfigureability. Connectivity is provided via a manual Fibre Optic Patch Panel, a patch panel where equipment within an office is connected via fiber cables to one side (typically in the back), and where short patch cables are used on the other side (typically in the front) to manually interconnect the equipment as desired.  There is a point that Fibre Optic Patch Panel, people usually different ports patch panel , for example, 6, 8, 12, 24 port fiber patch panel and they according to different connectors to choose different patch panel, such as LC patch panel,  LC patch panel,  MTP patch panel…
 
optical network
 
The traffic that is being added to or dropped from the optical layer at this node is termed add/drop traffic, the traffic that is transmitting the mode is called through traffic. Regardless of the traffic type, note that all of the traffic entering and exiting the node is processed by a WDM transponder. In the course of converting between a WDM-compatible optical signal and a client optical signal, the transponder processes the signal in the electrical domain. Thus, all traffic enters the node in the optical domain, is converted to the electrical domain, and is returned to the optical domain. This architecture, where all traffic undergoes optical electrical (OEO) conversion, is referred to as the OEO architecture.

2019年6月12日星期三

Differences between EPON and GPON

PON is the abbreviation of passive optical network, which only uses fiber and passive components like fiber splitter and combiner. EPON (Ethernet PON) and GPON (Gigabit PON) are the most important versions of passive optical networks, widely used for Internet access, voice over Internet protocol (VoIP), and digital TV delivery in metropolitan areas. Today we are going to talk about the differences between EPON and GPON.
 
Technology Comparison of EPON and GPON
EPON is based on the Ethernet standard 802.3 that can support the speed of 1.25 Gbit/s in both the downstream and upstream directions. It is well-known as the solution for the “first mile” optical access network. While GPON, based on Gigabit technology, is designated as ITU-T G.983 which can provide for 622 Mbit/s downstream and 155 Mbit/s upstream. GPON is an important approach to enable full service access network. Its requirements were set force by the Full Service Access Network (FASN) group, which was later adopted by ITU-T as the G.984.x standards–an addition to ITU-T recommendation, G.983, which details broadband PON (BPON).
 
As the parts of PON, they have something in common. For example, they both can be accepted as international standards, cover the same network topology methods and FTTx applications, and use WDM (wavelength-division multiplexing) with the same optical frequencies as each other with a third party wavelength; and provide triple-play, Internet Protocol TV (IPTV) and cable TV (CATV) video services.
 
Costs Comparison
No matter in a GPON or in an EPON, the optical line terminal (OLT), optical network unit (ONU) and optical distribution network (ODN) are the indispensable parts, which are the decisive factor of the costs of GPON and EPON deployments.
 
The cost of OLT and ONT is influenced by the ASIC (application specific integrated circuit) and optic module. Recently, the chipsets of GPON are mostly based on FPGA (field-programmable gate array), which is more expensive than the EPON MAC layer ASIC. On the other hand, the optic module’s price of GPON is also higher than EPON’s. When GPON reaches deployment stage, the estimated cost of a GPON OLT is 1.5 to 2 times higher than an EPON OLT, and the estimated cost of a GPON ONT will be 1.2 to 1.5 times higher than an EPON ONT.
 
We all know that the ODN is made up of fiber cable, cabinet, optical splitter, connector, and etc. In the case of transmitting signals to the same number of users, the cost of EPON and GPON would be the same.
 
Summary
Nowadays, since many experts have different opinions on EPON and GPON. Thus, there is no absolute answer to determine which is better. But one thing is clear: PON, which possesses the low cost of passive components, has made great strides driven by the growing demand for faster Internet service and more video. Also, fiber deployments will continue expanding at the expense of copper, as consumer demands for “triple-play” (video, voice and data) grow.

Functions of ONT and OLT in GPON Network

Gigabit passive optical network (GPON) is a point-to-multipoint access mechanism providing end users with the ability to consolidate multiple services onto a single fiber transport network. To realize this technology, many devices are used to support the network, such as optical splitter, ONT, OLT, etc. In this article, we will mainly discuss the functions of ONT and OLT in GPON network.
 
Functions of ONT and OLT
Optical network terminal (ONT) is an optical modem that connects to the termination point with an optical cable. It is used at end user’s premise to connect to the PON network on one side and interface with the user on the other side. Data received from the customer end is sent, aggregated and optimized by the ONT to the upstream OLT. ONT is also known as optical network unit (ONU). ONT is an ITU-T term, while ONU is an IEEE term. They both refer to the user side equipment in GPON network. A small difference between them might be the application locations. ONU can work in different temperature and weather conditions.
 
Optical line terminal (OLT) is the endpoint hardware equipment located in a central office of the PON network. Its basic function is to control the float information in optical distribution network (ODN) to go in both directions. OLT converts the standard signals used by fiber optic service (FiOS) to the frequency and framing used by PON system. In addition, it coordinates the multiplexing between the ONT conversion devices. There are two float directions for OLT system. One is the upstream direction to distribute different types of data and voice traffic from users. The other is the downstream direction which gets data, voice and video traffic from metro network or from a long-haul network and sends it to all ONT modules on the ODN.
 
How to Add or Delete ONT on OLT?
Way to Add ONT on OLT
If the password of an ONT is obtained, you can run the ONT add command to add the ONT offline. However, if the password is unknown, you can run the port portid ont-auto-find command in the GPON mode to enable the ONT auto-find function of the GPON port, and then run the ONT confirm command to confirm the ONT. When the ONT is added, you need to run the display ONT info command to see the current status of ONT. If the control flag is active,
 
Way to Delete ONT on OLT
When you need to delete the ONT on OLT, please use the delete command. Then ONT configuration data is deleted with the deletion of the ONT and the online ONT is forced offline. ONT can’t be deleted when it has been configured with other services. You need to unbind the service first before delete the ONT.
 
How to Troubleshoot ONT?
To troubleshoot the ONT, you should remember that the most important step is to connect your computer directly to the ONT to see if the problem goes away. You can use the Ethernet cable for connection. If the problem still exists, you can reconnect the ONT power supply to clear its internal cache. If the network can not be restored after the above methods, maybe you need to consult professionals for help.
 

Media Converters Provide Cost-effective Soluton

Network complexity, demanding applications, and also the growing number of devices around the network are driving network speeds and bandwidth requirements higher and forcing longer distance requirements within the LANs. However, Media Converters provide solutions to these complaints, utilizing the optical fiber if it is needed, and integrating new equipment into existing cabling infrastructure.
 
What is the Media Converter? Media converter can be a device that functions like a transceiver, converting the electrical signal found in copper UTP network cabling into light waves used in fiber optic cabling. It gives you seamless integration of copper and fiber, and other fiber types in Enterprise LAN networks. Media converter supports numerous protocols, data rates and media types.
 
Fiber optic connectivity is important when the distance between two network devices exceeds the transmission distance of copper cabling. Copper-to-fiber conversion using media converters enables two network devices with copper ports to become connected over extended distances via fiber optic cabling. Media converters provide fiber-to-fiber conversion from multimode fiber to single-mode fiber or single-mode fiber to multimode fiber, and convert a dual fiber link to single fiber using Bi-directional (BIDI) data flow. They can also convert between wavelengths for WDM applications with devices such as WDM multiplexer. Media converters are typically protocol specific and are available to guide a wide variety of network types information rates.
 
For example, the Fiber-To-Fiber Media Converter can offer connectivity between multimode and single-mode fiber, between different power fiber sources and between dual fiber and single-fiber. It extends a multimode network across single-mode fiber with distances as much as 140km. Within this application, two Gigabit Ethernet switches equipped with multimode fiber ports are connected by using a couple of Gigabit Fiber-To-Fiber Media Converters, which convert the multimode fiber to single-mode and let the cross country connection between the switches. Furthermore, they support conversion from one wavelength to a new with all the single mode to multimode converter or multimode to singlemode media converter. These media converters are usually protocol independent and designed for Ethernet,and TDM applications.
 
Media converters do a lot more than convert copper-to-fiber and convert between different fiber types. Media converters for Ethernet networks can support integrated switch technology, and offer the opportunity to perform 10/100M and 10/100/1000M rate switching. Additionally, media converters can support advanced bridge features, including VLAN, QoS prioritization, Port Access Control and Bandwidth Control – that facilitate the deployment of recent data, voice and video to get rid of users. Media converters can offer all these sophisticated switch capabilities in a, cost-effective device.
 
Media converters save CAPEX by enabling interconnection between existing switches, servers, routers and hubs; preserving the investment in legacy equipment. They reduce CAPEX by avoiding the necessity to install new fiber links by enabling WDM technology through wavelength conversion. Media converters also reduce network OPEX by helping troubleshoot and remotely configure network equipment that is at distant locations, not waste time and funds when there is not just a network administrator on the distant location.
 
Media converters are necessary to produce a more reliable and cost-effective network nowadays. So, where are we able to get high quality Media Converters with reasonable price? Visit Fiber Media Converter Solution in fiber-mart.com now.

2019年6月10日星期一

CWDM System Testing Process

With the explosion of CWDM, it is very necessary to formulate a basic testing procedure to certifying and troubleshooting CWDM networks during installation and maintenance. Today, one of the most commonly available test methods is the use of an OTDR or power source and meter, which is capable of testing the most commonly wavelengths, 1310, 1490, 1550 and 1625nm.
 
This article here is based on the pre-connectorized plug and play CWDM systems that allow for connecting to test equipment in the field:
 
In the multiplexing module of a pre-connectorized CWDM system, wavelengths are added to the network through the filters and transmitted through the common port. The transmitted wavelengths enter the COM port in the de-multiplexing module and are dropped. All other wavelengths present at the MUX/DeMux module are went through the express port.
 
Most of today’s OTDRs have expanded capability for testing wavelengths in addition to 1310 and 1550 nm. The OTDR allows partial testing of such system offered in test equipment source. The OTDR allows partial testing of these systems by using the flexibility of pre-connectorized solutions. This is done by switching connections within the CWDM field terminal to allow for testing portions of the non-1310/1550 nm optical paths.
 
To test the 1310nm, the first step is to test the downstream portion of a system at 1310 nm by connecting the OTDR to the 1310 nm input on the CWDM MUX located at the headend. Then switch the test leads over the the upstream side and repeat. Test method is the same for both the downstream and upstream paths.
 
1550 nm testing is performed similarly by switching the test leads to the 1550nm ports. If additional wavelengths are present, you need to follow the procedures below:
 
Using the 1550 nm test wavelength, switch the OTDR connection to the 1550 nm input port on the headend MUX. Have a technician stationed at the field terminal connect the drop cable leg connectors for the 1570 nm customer to the 1550 nm port on the Mux/demux device. What should be noted is that in a play and plug solution this should not require repositioning where the drop cable passes through the OSP terminal. Test the downstream 1570 nm passive link at 1550 nm, and then repeat for the 1570 nm upstream side. When testing is complete, have the technician switch the connections for the 1570 nm drop back to the 1570 nm ports on the field MUX/DeMUX device as shown in Figure 6. Repeat this process for the 1590 nm, 1610 nm drop cables and other wavelengths present. Finally, test the 1550 nm path normally with the 1550 nm drop cable connected to the 1550nm MUX/DeMUX ports.
 
Since the OTDRs is able to test at 1490 or 1625 nm, the drop cables under test could be connected to the EXP port of the module and tested at 1490 or 1625 nm respective wavelength, without having to connect each to the 1550 nm port. Otherwise the procedure is the same.
 
As CWDM network become more and more common the data they carrying has also become critical. The procedure introduced here allows for testing modular pre-connectorized CWDM systems with standard optical test equipments. Relative channel power can be measured with a wide-band fiber optic power meter at the filter outputs or at other points in the network with the aid of a wavelength selective test device or with an optical spectrum analyzer.