Category Archives: Fiber Optic Transmission

How to build a Fiber Optic CATV/HFC Network

HFC/CATV Network Overview
CATV, which originally called community antenna television is much more often called “cable TV” for people. As the rapid growth of the amount of residential Internet users and the increased bandwidth requirements of multimedia applications have necessitated the development of an access network that can support the need for such services.HFC/CATV networks appear to be within an important position for supporting these types of services.

An HFC/CATV network typically uses coaxial cable for short runs between peripheral equipment and also the transmitter or cable receiver at the user end. At the same time, optical transmission links between headends use singlemode fiber to greatly extend the transmission distance. This combination permits the system designer to maximise costeffectiveness when choosing the system components.

HFC/CATV network develops in an evolutionary manner. A one-way, broadcast analog video service just by replacing the trunk coax cable with fiber is first appeard. Optical transmitters are placed in the headend and the fiber is terminated with optical nodes. The optical nodes are temperature hardened, environmentally sealed containers capable of being placed underground or hung off poles. The optical nodes can transport a slew of modules for example optical receivers to convert the optical signal to an electrical format for distribution within the coax network. The next phase ended up being to upgrade the plant to supply two-way services. The unused 5 to 42 MHz spectrum can be used for upstream communication for example cable modem data. Upgrading to two-way involves having two-way amplifiers and putting optical transmitters within the optical nodes so as to transport the return signals in the customer premises to the headend. At the headend an optical receiver is required for every return fiber in the node. Adding two-way capability to the plant permits the cable operator to provide video, voice and knowledge.

How to build a HFC/CATV Network?
A traditional HFC/CATV distribution system includes 3 layers:
First, supertrunks carry signals over long distances. Distances of 100 km might be achieved rich in signal fidelity, having a single fiber link; Second, feeder links typically span a shorter distance and fasten a fiber hub (supertrunk termination) to a fiber node. Nodes are the reason for a network at which fiber is converted back to RF – this amplified RF is usually fed over coaxial cable to some number of CATV set top boxes. The feeder link inside an HFC system is roughly equal to the sort of link that the business or campus would use to extend CATV coverage over a distance that’s more than is possible with high fidelity over coaxia cable; Third, a drop is usually a link connecting one tuner. If distance is prohibitive of coaxial cable, this link may also be implemented with fiberoptics.

HFC/CATV Networks building cases
Small Private HFC/CATV Networks (Figure 1.)

small pricate catv networksFigure 1. Small Private HFC/CATV Networks

Small to Medium Size Private HFC/CATV Networks (Figure 2.)

small to medium size pricate network

Figure 2. Small to Medium Size Private HFC/CATV Networks

Large Scale Campus and Municipal Networks (Figure 3.)

large scale campus and municipal networksFigure 3. Large Scale Campus and Municipal Networks

Why choose Fiberstore for your HFC/CATV network building solution?
Fiberstore is a professional optical products company. As the HFC/CATV network develops very rapidly, the high demands of HFC optic fiber products is urging the devices providers to improve themselves. Fiberstore has specialized in the development and improvement of HFC optic fiber products for HFC/CATV network, especially the optical transmitters (see the Figure 4.)
TRANSMITTER

Figure 4. Fiberstore optical transmitters

Advantages of Fiberstore Optical Transmitters:
Pre-distortion circuit makes product have excellent non-linear index, ensure optical fiber network and long-distance transmitting, make out users cover.
Microprocessor circuit and VFD, for control and display optical transmitter work status and parameter.
Perfect Laser control and protect circuit, ensure the stable reliable work capability

Fiberstore Optical Transmitters Applications:
1310 broadcast and narrow cast applications
CATV forward path
RF over fiber

There are more products of CATV optical Transmission which will help you make your item works perfectly, know more, click here!

Synchronous Optical Networking Introduction

Synchronous Optical Networking is usually called SONET for short. The SONET standards were coded in the mid-1980s to consider benefit of low-cost fiber optic transmission. It defines a hierarchy of data rates, formats for framing and multiplexing the payload data, as well as optical signal specifications (wavelength and dispersion), allowing multi-vendor interoperability.

SONET may also be referred to as “T-1 on steroids”. Can you explain that? As you may know, the digital hierarchy (DS-0, DS-1, DS-2, DS-3 and much more) was created to provide cost-effective multiplexed transport for voice and data traffic from one location inside a network to a separate.

SONET and SDH (Synchronous Digital Hierarchy) are two equivalent multiplexing protocols for transferring multiple digital bit streams using lasers or LEDs (light-emitting diodes) over the same optical fiber. They were made to replace PDH (Plesiochronous Digital Hierarchy) system to get rid of the synchronization issues that PDH Multiplexer had. SONET is synchronous, which means that each connection achieves a continuing bit rate and delay. For example, SDH or SONET might be utilized to allow several Internet Service Providers to talk about exactly the same optical fiber, without being affected by each others traffic load, and without having to be able to temporarily borrow released capacity from one another. SONET and SDH are considered to become physical layer protocols since they offer permanent connections and do not involve packet mode communication. Only certain integer multiples of 64kbits/s are possible bit rates.

SONET is really TDM(time division multiplexing) based and this causes it to be readily supported fixed-rate services such as telephony. Its synchronous nature is designed to accept traffic at fixed multiples of the basic rate (64kbit/s), without requiring variable stuff bits or complex rate adaptation.

The SONET data transmission format is based on a 125us frame composed of 810 octets, of which 36 are overhead and 774 are payload data. The fundamental SONET signal, whose electrical and optical versions are referred to as STS-1 and OC-1, respectively, is thus a 51.84Mb/s data streams that readily accommodate TDM channels in multiples of 8 kb/s.

It is important in fiber optic network that SONET can be used to encapsulate PDH and other earlier digital transmission standards. It is also used directly to support either an ATM (Asynchronous Transfer Mode) or packet over SONET/SDH (POS) networking. So SONET/SDH is actually a generic all-purpose transport container for moving both voice and knowledge traffic. They in themselves aren’t communications protocols.

SONET brings by using it a subset of benefits that make it differentiate themselves from competitive technologies. These include mid-span meet, improved operations, administration, maintenance, and provisioning (OAM&P), support for multipoint circuit configurations, non-intrusive facility monitoring, and the capability to deploy a variety of new releases.

Improved OAM&P is among the greatest contributions that SONET brings to the networking field. Element and network monitoring, management, and maintenance has always been something of the catch-as-catch-can effort due to the complexity and diversity of elements inside a typical service provider’s network. SONET overhead includes error-checking ability, bytes for network survivability, and a diverse set of clearly defined management messages.

Related Article: How Much Do You Know About SONET/SDH SFP Module?