CN2703364Y - Amplitude-modulated optical transmitter - Google Patents
Amplitude-modulated optical transmitter Download PDFInfo
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- CN2703364Y CN2703364Y CNU2004200179189U CN200420017918U CN2703364Y CN 2703364 Y CN2703364 Y CN 2703364Y CN U2004200179189 U CNU2004200179189 U CN U2004200179189U CN 200420017918 U CN200420017918 U CN 200420017918U CN 2703364 Y CN2703364 Y CN 2703364Y
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Abstract
The utility model relates to an amplitude-modulated optical transmitter, comprising a radio frequency signal processing unit, a laser device, a control unit and a power supply system. The radio frequency signal processing unit is equipped with an automatic gain control (AGC) circuit with a large regulating and controlling scope and a radio frequency signal predistortion non-linear compensation circuit with large improvement of the distortion degree (8-12dB). The power supply system is equipped with a heat backup main and backup switch power supply which offers main and secondary working current simultaneously. The utility model can be widely applied to the broad band synthesis information network, which transmits the multinomial business of television, data and sound, etc., and the utility model is the key transmission equipment of the broad band access network. When the network works normally, the multi-port input makes the optical transmitter insert the transmission of the other service information when the original information source transmission is not interrupted, and the adaptability of the optical transmitter is particularly strong when using. The price ratio of the utility model is excellent, the stability is high, the improvement expense of the cable television network can be reduced greatly, and the transitional process of the cable television network from simulation to digital in China is accelerated.
Description
Technical field
The utility model relates to cable TV network broadband laser transmission technique field, particularly a kind of AM light transmitter.
Background technology
Cable TV network has become the important component part of China's informatization and network, the pure coaxial cable TV network of the eighties only limits to watch tens cover TV programme, after the nineties, along with the continuous expansion of optical fiber transmission technique in the application of cable TV field, cable TV network is progressively to broadband, highly reliable, transmission capacity is big, the Hybrid Fiber and Coax Network HFC that transmission speed is high (HFC net) development, because the HFC netting gear has the unrivaled wideband advantage of other networks, make it when satisfying traditional TV reception, also can open multiple value-added service, as pay TV, video request program, Digital Television, Web bank, the internet service, IP phone etc. have the function of unification of three nets.
Optical fiber transmission technique is broadband AM light transmitter and optical receiver in the hfc plant key issue in application.Broadband AM light transmitter is that the broadband rf signal with required transmission carries out amplitude modulation(PAM) to laser, thereby obtains required transmission light energy so that transmit in optical fiber.Existing AM light transmitter all exists some defectives and deficiency aspect reliability and the applicability.
Summary of the invention
The purpose of this utility model provides a kind of reliability height, the broadband AM light transmitter that applicability is strong.
Said AM light transmitter comprises radiofrequency signal processing unit 2, laser and control unit 3 and Hot Spare power-supply system 1, it is characterized in that: a big modification scope (± 4dB) automatic gain control (AGC) circuit 6 is set in the radiofrequency signal processing unit, the input of said (AGC) circuit 6 is connected with the output of pre-amplifying circuit 5, and (AGC) output of circuit 6 is connected with the input of power amplification circuit 7.In radio frequency signal processing circuit, also be provided with distortion and improve big (8-12dB) radiofrequency signal predistortion non-linear compensation circuit 8 of degree, the input of predistortion circuit 8 is connected with the output of power amplification circuit 7, and the output of predistortion circuit 8 is connected through the input of matching network 10 with laser 11.
In power-supply system, being provided with provides the Hot Spare of groundwork electric current and underwork electric current active and standby Switching Power Supply simultaneously, the power input of the active and standby Switching Power Supply of Hot Spare all is connected with city's electrical network, the output of main switch power supply is connected with the amplitude modulated transmitter basic load, and the output of Hot Spare backup circuit breaker power supply is connected with the less important load of AM light transmitter.Be provided with among the CPU in laser and control unit 3 its laser bias current implementation is disconnected, slightly controls and three grades of control programs of smart control.In the radiofrequency signal processing unit, be provided with and utilize two-way radiofrequency signal (RF) input port that can receive data-signal and TV signal after the frequency division simultaneously.Pre-amplifying circuit 5 adopts the GaAs amplifier, and power amplification circuit 7 adopts BGD system silicon amplification module, and laser 3 adopts the Distributed Feedback Laser assembly, and laser and control unit 3 adopt the control of 89C51 microprocessor.
In described radiofrequency signal processing unit, the range of AGC of general optical sender is at ± 2dB, because the multifunctional development of cable TV network will constantly increase the number of channels of its transmission, cause its synthetic level changes in amplitude bigger, for adapting to the network demand in future, the range of AGC of optical sender reaches ± 4dB, and the advantage that control range is big is fairly obvious.One when channel number from tens to more or less a hundred changes, need not to adjust the radio frequency incoming level of complete machine, and the adaptability of complete machine is stronger; Its two owing to during the variation of optical sender prime radio frequency level generation certain limit, also need not to adjust the radio frequency incoming level of complete machine, reduced the maintenance of system, guaranteed the stable of whole system.
In described predistortion circuit, because the luminous power-current characteristics of laser exists certain non-linear, thereby influenced the non-linear index of complete machine, for improving the non-linear index of complete machine, optical sender is after power amplification, additional dexterously distorted characteristic of the utility model and the opposite circuit of laser modulation characteristic nonlinear distortion, make the multichannel radio signal of input carry out anti-distortion through oversampling circuit in advance, and then the de-energisation modulated laser, thereby being cancelled each other, two distortions reach the compensation purpose.The opposite property of the strict control of optical sender predistortion circuit and laser modulation characteristic nonlinear distortion makes the degree of second-order distortion improvement reach 8-12dB.
The suitable voltage range wide (110-254V/AC) that described optical sender adopts, the Switching Power Supply that efficient is high, guaranteed the normal use of complete machine in the bigger region of scope range of the fluctuation of voltage, adopt Switching Power Supply to improve the power supply conversion efficiency height, reduced the additional power consumption of complete machine.Be provided with the Switching Power Supplies of the same circuit of two covers in the optical sender, and every cover Switching Power Supply can both satisfy the power supply needs of complete machine separately, also leaves 30% redundant electricity consumption space simultaneously.Traditional Hot Spare power-supply system function is: during complete machine work, two power supplys start simultaneously, wherein have only main power source to supply complete machine work separately, and stand-by power supply is in the output of stand-by state no current, when main power source is out of order, just switches on the stand-by power supply.Electric power system with warm standby function is compared with the separate unit electric power system, and its failure rate can descend 50%.The pattern that the Hot Spare power-supply system of optical sender has adopted comparatively advanced primary and secondary power to power simultaneously provides main electric current by main power source during operate as normal, and accessory power supply provides secondary current, when main power source breaks down, and the automatic oepration at full load of accessory power supply.The advantage of this major-minor while Hot Spare power supply is: one, during operate as normal, because active and standby power supply supplying electric current simultaneously, the fault that has easily caused under the high-power state at full capacity when having overcome active and standby power supply and powering has separately prolonged power supply useful life.Its two because equipment is in 24 hours open states for a long time, when active and standby power supply is powered simultaneously, overcome the long-term no current output of stand-by power supply and lacked the fault that operation causes.Its three, active and standby power supply is identical, can both satisfy the need for electricity of complete machine separately, and the working condition that can easily check the Hot Spare power-supply system by the RS232 interface and the RS485 interface of microprocessor.The Hot Spare power-supply system of optical sender descends the failure rate of complete machine to 70%.
Described laser and control unit are the Distributed Feedback Laser assembly, and it comprises the DFB-LD chip, are used for the photo detector chip of optical power detecting and auto light power control; The semiconductor cooler and the thermistor that are used for two-way automatic temperature-adjusting control are used to reduce optical isolator and optical fiber coupling unit and wideband impedance match driving and bias current and the control circuit that extraneous retroeflection influences.
For guaranteeing laser works in the range of linearity, it is crucial selecting suitable bias current, and stack cable TV wide band radio-frequency Signals in Laser device carries out amplitude modulation(PAM) on bias current, thereby obtains the light energy of required transmission.For making laser be operated in the range of linearity and operation steady in a long-term preferably, must control the luminous power of output, by the luminous power detection tested luminous power is taken out with the form of electric current, be used for monitoring the variation of Output optical power in the laser works process, and control (APC) loop with auto light power variable power is followed the tracks of, in time change the biasing circuit of laser automatically, Output optical power is remained unchanged.Change owing to the luminous power-current characteristics curve of laser can vary with temperature, must keep the working temperature of laser constant.Under the control of two-way closed loop thermal control circuit (ATC) and thermistor (temperature) sensor, when temperature raises, the electric current of semiconductor cooler is crossed refrigerator and refrigeration cooling with regard to positive flow, and current reversal flows through refrigerator and pyrogenicity heats up when temperature reduces, thereby reaches two-way temperature control.
The AM light transmitter has selected for use the 89C51 single-chip microcomputer as microprocessor, it can control the operating state of auto light power control (APC) loop effectively, the optimum Working parameter of the optical sender that dispatches from the factory is deposited in the microprocessor, when the parameter of actual working state changes, microprocessor in time sends the parameter that automatic optical power control circuit is adjusted in instruction, make it be operated in optimum state, and in time note the various historical datas in the operating time.The working temperature of laser is all very big to the linearity and the relative intensity noise influence of the operating efficiency of laser, laser, must the strict working temperature of controlling laser remain on 25 ℃.The automatic temperature-adjusting control unit places chip of laser on the tight enthusiasm that is connecting micro semiconductor refrigeration, and thermistor is housed on enthusiasm, form a two-way closed control circuit (ATC) by temperature control system, this control circuit is controlled by microprocessor fully, the flow direction size of control refrigerator electric current.When temperature raise, the refrigerator electric current was with regard to positive flow and refrigeration; When temperature reduced, electric current is stream and pyrogenicity just in the other direction, realizes two-way temperature control, thereby keep that laser is constant to be operated in 25 ℃.
Various parameters during the microprocessor unit internal memory contain laser assembly operate as normal of optical sender are divided the work of three grades of control laser bias currents through its.When the excursion of bias current exceeds it and allows maximum to cause laser to damage, control circuit will disconnect the power supply of supplying with laser, after protection laser, running parameter recover normally, microprocessor is controlled its bias current and is loaded on the laser, recovers its operate as normal automatically; When bias current exceeds its smart control scope and does not reach it again and allow maximum, earlier it is implemented thick control, bias current is adjusted to smart control scope, by smart control circuit bias current is accurately controlled again; When bias current has only minor variations, directly carry out the essence control, its control precision and control range are all increased.Microprocessor unit links to each other with the liquid crystal display circuit of complete machine, just can in time check the working condition of complete machine easily in this locality, judges the fault coverage of complete machine quickly and accurately.Microprocessor unit monitoring the refrigeration electric current of bias current, automatic temperature-adjusting control unit of optical output power, the laser of working temperature, the optical sender of laser and operating voltage (comprise+24V ,+5V ,-5V).And with above data storage in microprocessor, by the LCD display circuit, just can obtain above data very easily by the operating key on the front panel, thereby judge the whether working properly of optical sender in this locality.When the running parameter of laser departs from the allowed band of microprocessor setting, with the automatic disconnection laser power supply, sound, light alarm (the panel red light is bright, buzzer sound in the machine) simultaneously, digitizing tablet prompting failure cause.Optical sender has been set up RS232 interface and RS485 interface that remote monitoring is used, and this two interface links to each other with microprocessor in the machine respectively, can directly call the various parameters of storing in the microprocessor by this two interface, reaches the purpose of remote monitoring.
Described two-way radiofrequency signal (RF) input port, the internet business just progressively is applied in cable broadband network at present, the application of this business belongs to the value-added service of cable television broadband network, be to guarantee that various cable television services carry out the value-added service on the basis, promptly guaranteeing to transmit the internet information source simultaneously on the various information source transmission of the cable television service basis, this just requires optical sender that the access port of plurality of information resources is arranged.
The utility model beneficial effect is: can be widely used in the broadband integration information network, multinomial business such as TV transmission, data and sound, be the critical transmissions equipment of broadband access network, the multiport input makes optical sender when network normally moves, the transmission that can in time insert other professional information sources easily when not interrupting original information source transmission, in use adaptability is strong especially to make optical sender.The utility model cost performance excellence, stability are high, can reduce the improvement expenses of cable television network greatly, accelerate the process of China's cable television network by the simulation-to-digital transition, and social benefit will be very huge.
Description of drawings
Accompanying drawing 1 is the utility model block diagram; Accompanying drawing 2 is the RF processing unit structural representation; Accompanying drawing 3 is laser and control unit block diagram; Accompanying drawing 4, pre-distortion unit schematic diagram; Accompanying drawing 5 is CPU control electrical schematic diagram.
1-Hot Spare power supply, 2-RF processing unit, 3-laser and control unit, 4-LCD panel display unit, the pre-amplifying circuit of 5-, 6-automatic gain control circuit, 7-power amplification circuit, 8-predistortion circuit, 9-detector amplifier, 10-matching network, 11-laser among the figure.
Embodiment
Engage accompanying drawing below, the utility model is described in further detail: its operation principle is such: radiofrequency signal is through the master, auxilliary rf input port is input to the pre-amplifying circuit 5 in the radiofrequency signal processing unit, through automatic gain control circuit (AGC) 6, power amplification circuit 7, predistortion non-linear compensation circuit 8 is loaded on the bias current of laser, laser is carried out amplitude modulation(PAM), thereby obtain the light energy of required transmission, and make the carrier-to-noise ratio height of the light energy of its output, nonlinear distortion is little, the Hot Spare master, stand-by power source guarantees the long-time running high reliability of complete machine, provide main electric current by main power source during operate as normal, accessory power supply provides secondary current, when main power source breaks down, the automatic oepration at full load of accessory power supply.In accompanying drawing shown in Fig. 1～4, automatic gain control (AGC) circuit and a distortion level that a big modification scope is set in the radiofrequency signal processing unit improve big (8-12dB) radiofrequency signal predistortion non-linear compensation circuit, in power-supply system, be provided with, active and standby part of Switching Power Supply of Hot Spare of primary and secondary operating current is provided simultaneously.The input of automatic gain control (AGC) circuit 6 is connected with the output of pre-amplifying circuit 5, and (AGC) output of circuit 6 is connected with the input of power amplification circuit 7.The input of described radiofrequency signal predistortion non-linear compensation circuit 8 is connected with the output of power amplification circuit 7, and the output of predistortion electrical equipment 8 is connected through the input of matching network 10 with laser 11.The power input of the active and standby Switching Power Supply 1 of Hot Spare all is connected with 220V/AC city electrical network, and the output of main switch power supply 1-1 is connected with the optical sender basic load, and the output of Hot Spare Switching Power Supply 1-2 is connected with the less important load of optical sender.The modification scope of 2 automatic gain (AGC) circuit 6 is ± 4dB in the radiofrequency signal processing unit.The distortion factor improvement degree of radiofrequency signal predistortion non-linear compensation circuit 8 is 8-12dB.
At the CPU of laser and control unit 3 is that a kind of storing can disconnect the laser bias current implementation, slightly control and the smart single-chip microcomputer of controlling three grades of control programs.In the radiofrequency signal processing unit, be provided with and utilize two-way radiofrequency signal (RF) input port that receives data-signal and TV signal after the frequency division simultaneously.Pre-amplifying circuit 5 adopts the GaAs amplifier.Power amplification circuit 7 adopts BGD system silicon amplification module.Laser 3 adopts the Distributed Feedback Laser assembly.Laser and control unit 3 adopt the control of 89C51 microprocessor.
Claims (7)
1. AM light transmitter, comprise radiofrequency signal processing unit, laser and control unit and power-supply system, it is characterized in that: automatic gain control (AGC) circuit and a distortion level that a big modification scope is set in the radiofrequency signal processing unit improve big (8-12dB) radiofrequency signal predistortion non-linear compensation circuit, are provided with active and standby part of Switching Power Supply of the Hot Spare that the primary and secondary operating current is provided simultaneously in power-supply system;
The input of described automatic gain control (AGC) circuit (6) is connected with the output of pre-amplifying circuit (5), and (AGC) output of circuit (6) is connected with the input of power amplification circuit (7);
The input of described radiofrequency signal predistortion non-linear compensation circuit (8) is connected with the output of power amplification circuit (7), and the output of predistortion electrical equipment (8) is connected through the input of matching network (10) with laser (11);
The power input of the active and standby Switching Power Supply of described Hot Spare (1) all is connected with 220V/AC city electrical network, the output of main switch power supply (1-1) is connected with the optical sender basic load, and the output of Hot Spare Switching Power Supply (1-2) is connected with the less important load of optical sender.
2. AM light transmitter according to claim 1 is characterized in that: the modification scope of the automatic gain of (2) (AGC) circuit (6) is ± 4dB in the radiofrequency signal processing unit; The distortion factor improvement degree of radiofrequency signal predistortion non-linear compensation circuit (8) is 8-12dB.
3. AM light transmitter according to claim 1 is characterized in that: at the CPU of laser and control unit (3) is that a kind of storing can disconnect the laser bias current implementation, slightly control and the smart single-chip microcomputer of controlling three grades of control programs.
4. AM light transmitter according to claim 1 is characterized in that: in the radiofrequency signal processing unit, be provided with and can utilize two-way radiofrequency signal (RF) input port that receives data-signal and TV signal after the frequency division simultaneously.
5. AM light transmitter according to claim 1 is characterized in that: pre-amplifying circuit (5) adopts the GaAs amplifier; Power amplification circuit (7) adopts BGD system silicon amplification module.
6. AM light transmitter according to claim 1 is characterized in that: laser (3) adopts the Distributed Feedback Laser assembly.
7. AM light transmitter according to claim 1 is characterized in that: laser and control unit (3) adopt the control of 89C51 microprocessor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2004200179189U CN2703364Y (en) | 2004-04-29 | 2004-04-29 | Amplitude-modulated optical transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2004200179189U CN2703364Y (en) | 2004-04-29 | 2004-04-29 | Amplitude-modulated optical transmitter |
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| Publication Number | Publication Date |
|---|---|
| CN2703364Y true CN2703364Y (en) | 2005-06-01 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNU2004200179189U Expired - Fee Related CN2703364Y (en) | 2004-04-29 | 2004-04-29 | Amplitude-modulated optical transmitter |
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| Country | Link |
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| CN (1) | CN2703364Y (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103345281A (en) * | 2013-06-27 | 2013-10-09 | 上海亨通宏普通信技术有限公司 | Temperature control device of high reliable wavelength division array optical waveguide |
-
2004
- 2004-04-29 CN CNU2004200179189U patent/CN2703364Y/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103345281A (en) * | 2013-06-27 | 2013-10-09 | 上海亨通宏普通信技术有限公司 | Temperature control device of high reliable wavelength division array optical waveguide |
| CN103345281B (en) * | 2013-06-27 | 2015-11-25 | 江苏亨通光网科技有限公司 | Temperature control device of high reliable wavelength division array optical waveguide |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |