First, the main scope of application:

The distribution of traditional broadcast-style cable television network, with the large and medium-sized cities in HFC network transformation, toward a two-way interactive communications network-style development. Passive optical network and passive coaxial cable distribution network HFC network structure will be the main mode. Goal is to set up a region-based information services provide a wide range of broadband multimedia communications platform. Fiber to the user to gradually extend the radius of node service gradually narrow, two-way user to gradually increase network reliability and service quality gradually improve, it will be the development trend of HFC network.
In order to meet this development to address the increasing two-way users share the bandwidth constraints, improve network quality of service, scalable four-port optical communications-based workstations, HFC broadband access network users the leading equipment. Widely used in optical fiber to the curb, fiber into the floor, fiber optic village.
As a result of market demand, many manufacturers to launch the four-port optical stations, but in aluminum die casting shell on how to solve the heat and the provision of functional space can be upgraded and so on, can not be compared with imported equipment, the current domestic market large-scale network The main use of imported equipment.
Chinese-made four-port optical station can not be replaced by imported equipment the key is not available for four-port optical communications station using cast aluminum shell. At present, generally use the 008 chassis. The chassis as a four-way high output optical receiver, has solved more than double the power module's heat (especially in summer simply can not work). As optical communications station, the case can not provide backup power supplies, optical collection module backup, more than return optical transmitter module and backup, network management modules, such as fiber optic fiber disk space available.
With reference to the United States SA, GI, ANTEC, C-COR, PHILIPS, such as the company's large four-port optical stations, the company designs tooling to align with the international community can replace the imported equipment for the cable television network to the broadband integrated services network to provide a high-quality two-way transmission platform.

二、Second, the main functional characteristics:
 (A) multi-channel high output:
With independent four-port high output, 59 Road, PAL-D, rated output level 9940A> 108dBμV, 9940B> 111dBμV. Passive cable distribution network with multi-channel devices require high output, can be used directly in the allocation of users to increase the coverage. No follow-active amplifiers, can be more thoroughly resolved reverse channel noise and interference of the funnel effect to ensure two-way business, quality of service.
 (B) Reliability:
Communications equipment for high redundancy.
1, power back-up: You can insert two highly efficient switching power supply, in a power failure, they can automatically switch to another power supply, switching time <0.15s.
2, optical backup: can insert two (can be expanded to four) optical receiver modules, receiving different routing of optical signals. When all the way light failure, controlled RF relays will automatically switch to another light on the road. Pluggable four return optical transmitter module can be composed of two-way return optical transmitter module thermal backup.
3, RF backup: the transformation in the HFC network, such as retention of the original cable network configuration with cable A / B switch RF motherboards, optical cable network in the event of a failure to automatically switch to the cable network.
(C) Flexibility: (can be configured, scalable)
HFC network to two-way interactive network development is a gradual process, it 1GHz as a communications platform, a variety of functional components all plug-in structure. The early stage can be configured for simple, complete the basic features. With the development of value-added services, adding new features module, using a simple plug way, you can upgrade at the scene.
1, functions can be configured:
⑴, single land type: a light collection, a power

⑵, two-way type: an optical collection, 1 ~ 4 light hair, a power

⑶, communication type: 2-ray collection, 1 ~ 4 light hair , 2 power supply, (available with network management unit)
⑷, relay-type: a 4 ~ 16mW of optical transmitter module, composed of four-port optical communications relay station
2, broadband can be extended:
HFC cable network, multi-functional service, the bandwidth requirements is endless. With the development of integrated circuit technology, as long as the replacement of amplification module, 750MHz can be extended to 862 MHz (or higher).
3, optional optical frequency division duplex 9940 Thai filters, using specially designed for small plug-in components, the existing four kinds of optional plug-ins:
⑴ 5-42/53-750 （9940207）     ⑶ 5-35/47-750（9940207/0） ⑴ 5-42/53-750 (9940207) ⑶ 5-35/47-750 (9940207 / 0)
⑵ 5-65/87-862 （9940208）     ⑷ 45-750MHz （9940208/0） ⑵ 5-65/87-862 (9940208) ⑷ 45-750MHz (9940208 / 0)
(D) maintainability:

1, a perfect work of the state of display and test port.
⑴, RF motherboard: output level of each road, back level, are equipped with-20dB test port.
⑵, optical receiver module: 10V/mW optical power detection (for Network), the less light alarm, output level-20dB detection.
⑶, optical transmitter module: 1V/mW optical power, 0.01V/mA bias current detection (for network), optical power show,-20dB drive-level testing.
⑷, power supply: AC60V, +24 V, +15 V (+5 V),-5V detection (for management).
2, installation and debugging easy maintenance.
⑴, each road RF output level, the slope of each road back level, each received light output level modules, each module only the light of the input level, can be independent debugging.
⑵, any failure of a function modules, such as amplification module, light collection, optical module, switching power supply, only two fixed stud screw open, you can replace at the scene. RF replacement motherboard tray, power lines.
⑶, fiber optic and optical components in the shell covered with all devices, pulling two latches, they can facilitate the removal from the main shell can weld on the ground and with defibrillators.
⑷, with a dedicated fiber distribution boxes, can be installed 6 to 8 enamel disc.

Third, BOH-7448 main technical indicators (a) light-entry and some of the major technical indicators RF

(B) return optical transmitter module main technical indicators

Fourth, BOH-7448 main configuration diagram

Fifth, the main feature (a) RF motherboard:
1,9940201 without cables with cable 2,9940202 backup backup 3,9940203 light relay station can be equipped 4,9940204 six-port output (b) optical receiver modules:
1,9940213 used BGY887BO/FC-APC optical modules

2,9940214 used 2609B + BGY787
3,9940215 using PD control (such as FU-17PD-F1) + BGY787
(C) optical transmitter module:
1,9940216 using FP lasers 2mW (mass data)
2,9940217 Uncooled DFB laser is used 2mW (Chuan-1 ~ 4-way video)
3,9940218 Uncooled DFB laser is used 4mW (Chuan-1 ~ 4-way video)
4,9940219 Uncooled DFB laser with a 1 ~ 6mW (mass multi-channel video)
5,9940220 Uncooled DFB lasers with a 4 ~ 16mW (for optical relay station)
(D) switching power supply:
1,9940205 output +24 V, +15 V,-6V
2,9940206 output +24 V, + 5V,-5V
(E) adapter plate:
1,9940221 2 admission (home preparation), 4 fat, 2 power supply (the main preparation), network management interface 2,9940222 2 admission (home preparation), 4-fat (2 master 2 Preparation), 2 power supply (the main preparation), net tube interface 3,9940223 2 admission (home preparation), 4 fat, 1 jiguang fat, 2 power supply (the main preparation), network management interface (f) components:

1,9940207 42/53MHz Diplexer 2,9940208 65/87MHz Diplexer 3,9940207 / 0 35/47MHz Diplexer 4,9940208 / 0 45-862MHz Diplexer four straight plug 5,9940210 Optical Return Chuan Rd 6,9940211 adapter plate light return 7,9940307 RF adapter board jumper (SMB-C-TK3, cable 75-1.5-1-40cm
8,9940308 American-style plug-ATT fixed 9,9940312 adjustable equalizer 10,9940313 fixed equalizer plug-ins Plug-ins

6, BOH-7448 applications in the system several issues (a) Light Station and the ordinary optical receiver of the main differences:
1, an ordinary optical receiver used mainly for fiber optic transmission backbone, users covered mainly by the completion of the cable network. Therefore, indicators of distribution system is generally the front-end (0.1): fiber optic cable (0.4): Cable (0.5), optical cable for some indicators C / N = 48.7dB, CTB = 65dB, CSO = 59dB. Therefore, in engineering applications should try to reduce the optical receiver input optical power, generally low-2dBm or retraining. This will ensure that C / N indicators as well as lower the cost of the project. Distortion indicators to improve the cable network to allow more follow-up amplifiers, increasing coverage.

2, four-port optical station for direct coverage of the major users, in part because cable does not require the allocation of indicators, the indicators of the distribution system is generally the front-end (0.1): fiber optic cable (0.7): set-top boxes (0.2), while some indicators of fiber optic cable for C / N = 45.6dB, CTB = 56.6dB, CSO = 56.6dB. That is to say four-port optical station is entirely possible by improving the output level to increase the coverage. Therefore, in engineering applications, can increase the four-port optical input optical power stations, but generally +2 dBm. With the general optical receiver-2dBm compared to receive optical power, RF output level increase 8dBμV. A port output level theoretically equivalent to 4 general optical receiver coverage ability.
 (B), four-port optical output level stations to choose:
General users want to see the four-port optical station can output a high level in order to increase coverage, but the output level by the end of class (and promote the level) power amplifier module Specifications constraints. At present, the international station at the end of class 750MHz Optical amplifier generally use Philips BGD702 (using high-grade BGD702D) module reference to these two indicators are as follows:

In engineering applications, users should be based on the actual transmission of the channels, control output level to ensure that distortion indicators.
 (C) four-port optical station RF gain motherboard options:

Four-port optical station RF motherboard is based on internationally accepted model of the design, gain selection has been taken into account at the end of class power amplifier module BGD702 constraints of technical indicators, so to promote the general level select only two kinds of zoom modules:

By lowering the cost of the project of a general user would like to receive a lower optical power can have a higher output level, which means hope that the four-port optical station RF motherboard for a higher gain. Increase the RF gain motherboard will easily lead to self-excited, so that output indicators deterioration. In engineering applications should be reasonably designed to receive optical power nodes.

7, Installation Notes

 (A) BOH-7448 aluminum casting machine covered with eight hexagonal screws, installation should be twisted tight on the energy needed to balance, to prevent leakage.
(B) of the case are two positions can be rehoused two optical receiver module, the left side of the first main receiver, the second for backup. Only the installation of a light collection module can only be installed in the main receiving position, mounted on a stand-bit does not work.
(C) There are four locations on the chassis can be resettled in four optical transmitter module, installed in any one location can be, but must be RF jumper inserted in the corresponding SM outlet.
(D) return optical transmitter module has built a 5-200MHz, 24dB amplification module, using FC / PC connector. Return optical transmitter module RF drive level should be based on the actual situation in the project for debugging.

Eight, warranty and maintenance matters

 (A) provide one-year warranty, the warranty expired, can provide life-long maintenance and equipment upgrades.
(B) To ensure that the optical modules and to enlarge the reliability of modules. The local factory were 24-hour high-temperature aging, unreliable device in aging screening. As a result of improper use, such as electricity, lightning, grounding bad and man-made device failure caused by damage, the need to collect material costs.