CN2247402Y - Digital terminal adapter for cable television comprehensive service network - Google Patents
Digital terminal adapter for cable television comprehensive service network Download PDFInfo
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- CN2247402Y CN2247402Y CN96209993U CN96209993U CN2247402Y CN 2247402 Y CN2247402 Y CN 2247402Y CN 96209993 U CN96209993 U CN 96209993U CN 96209993 U CN96209993 U CN 96209993U CN 2247402 Y CN2247402 Y CN 2247402Y
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Abstract
The utility model relates to a digital terminal adapter for a cable television comprehensive service network. The utility model is composed of a radio-frequency modem and a network adapter, wherein, the network adapter comprises an ether interface, an ether-token converter, a token interface, a receiving and sending frame processor, etc. The radio-frequency modem comprises a radio frequency modulator and a radio frequency demodulator. The utility model can carry out the bidirectional data transmission on the existing cable television network, so that the long figure expenses of building the network can be saved; the range of communication of information runs through the housing area or the whole range of the enterprises and institutions; therefore, the utility model can extend the sharing range of the information source. The digital terminal adapter for a cable television network adaptor namely DTA lies in the leading position at home and abroad regardless of the hardware design, the protocol programming, and the software programming.
Description
The utility model relates to the communications field, particularly a kind of device that increases bidirectional data communication at existing cable TV on the net.
As the correlation technique of user network, particularly wire cable TV data transmitted in both directions technology has been done a large amount of work in the world, because the characteristics of various modulating systems and the different application of the information that transmits, thereby networks of different type has appearred.But the computer network that has bidirectional data transmission function at present all is used for industrial enterprise produces commander and public institution's office automation, its geographic range all is limited to territory under the unit, information also is only limited to our unit's circulation, the rate of information throughput is lower, the technical scheme that realizes communication also has nothing in common with each other, though some network transmission rate is higher, adopt the paired cable transmission line, the networking funds are very high.
The purpose of this utility model is: a kind of comprehensive service network for cable television digital terminal adapter that carries out bidirectional data transfers on existing cable television network is provided.
The purpose of this utility model is achieved in that
A kind of comprehensive service network for cable television digital terminal adapter is characterized in that: be made up of radio modem and network adapter; Wherein:
(1) network adapter comprises ether interface, ether-token transducer, parts such as token interface and receiving frame processor;
(2) radio modem comprises radio-frequency modulator and radio-frequency (RF) demodulator.
The receiving frame processor is scale programmable logic device fpga chip XC3042PC84, mainly finishes the receiving frame processing capacity; The sending part branch comprises parallel/serial conversion, additional frame starting and ending sign, and additional frame checking sequence FCS, scrambling processing and differential coding, receiving unit comprises digital phase-locked loop, scramble process, identification frame starting and ending sign calculates FCS result and serial/parallel conversion;
The major function of network adapter software and hardware (containing the translation function with two agreements of Taihe county token) is to be made of jointly four software modules among the microprocessor TMS320, comprise four funtion parts, token protocol master control modules A CM, data interface module IFM, Ethernet control module ETM, token transmitting-receiving control module RxM and TxM; Ether interface is two kinds of thick, cablet or twisted-pair feeders.
The ether interface of network adapter is connected with the computer ether interface, be connected with token interface with ether interface with Taihe county token transducer, token interface is connected with the receiving frame processor, the receiving frame processor is connected with the signal input part of radio-frequency modulator and the signal output part of radio-frequency (RF) demodulator respectively, and the output of radio-frequency modulator and the signal input part of radio-frequency (RF) demodulator are connected with wire cable television network CATV.The model of finishing with the microprocessor of two protocol conversion functions of Taihe county token can be TMS320 series or AM186EM series.
Owing to data, literal, sound, image request are had the function of bidirectional high speed communication on the net at cable TV, and can store them, duplicate, editor and calculation process, therefore just determined it must have the function that some utmost points have suitable attraction.As: computer media communication, VOD, public safety (fire-fighting, security personnel), video education, interactive video games (comprising Karaoke etc.), e-mail, information retrieval, video telephone, electronic business transaction, stock, house property, futures exchange, teletext, domestic system automation, domestic medicine etc.Can also increase new function as required.The utility model can not only bring huge economic benefit, and its social benefit can reflect significantly from its function.Its exploitation and construction will improve social productive forces widely, make things convenient for Human's production and life, save manpower, save time, raise the efficiency, reduce commercial undertaking's operating cost, if backbone is set up successively, the whole nation and even the whole world all will form this function, resource-sharing, information is shared, exchanges culture and business information each other, promotes common flourishing.
The utility model is described in further detail below in conjunction with drawings and Examples:
Fig. 1 system constitutes.
Fig. 2 user's node is provided with.
Fig. 3 digital terminal adapter (DTA).
The reference model of Fig. 4 network system interconnection.
Fig. 5 network adapter (1).
Fig. 6 network adapter (2).
The theory diagram of Fig. 7 radio modem.
The mode of frequency band division up and down of Fig. 8 two-way catv.
Fig. 9 radio modem motherboard circuit figure
Figure 10 network adapter motherboard circuit figure.
Referring to Fig. 1, comprehensive service network for cable television is on the cable TV technical foundation, utilizes the Broadband Computer Networks system of two channels foundation of coaxial cable Frequency Division Multiplexing system, and its topological structure as shown in Figure 1.Its physical topology is a tree.
In Fig. 1, send the data message that node will transmit microcomputer, convert the high-frequency signal that is loaded with this information to through modulation, it is transformed to descending high-frequency signal through some branch cables biographies to the network head end along the data feedback channel of cable, after trunk cable, distributor, splitter, branch cable demodulation, be input to the microcomputer that receives node.These two nodes also can carry out reverse link communication (at this moment node is carried out opposite transmission-receiving function) by similar approach.The user of every cable TV can carry out data communication each other by the cable TV interface box.Like this, the user is except that televiewing every day, a simultaneously available microcomputer is equipped with a network interface card, and adding a modulator-demodulator just can be with other online user of cable TV, TV station, master computer exchange message (literal, data, sound, image etc.) each user (node) outfit and connected mode thereof as shown in Figure 2.
Constitute the vitals digital terminal adapter (DTA) of network user's node by modulator-demodulator among Fig. 2 (radio frequency) and network adapter.
A. digital terminal adapter (DTA)
The radio modem (RF Modem) that constitutes DTA is made up of radio-frequency modulator and radio-frequency (RF) demodulator, and the network adapter of formation DTA comprises main functional parts such as ether interface, ether-token transducer, token interface, receiving frame processor.Their annexation as shown in Figure 3.
Carry out the ether agreement between DTA and interface and the computer ether interface, pass through digital terminal adapter (DTA) and wire cable television network for the computer of linking ether interface, realize data communication end to end with the ether agreement, constitute computer network with the Ethernet compatibility.And towards between the token interface of cable television network being the execution token protocol.Be to carry out two-way changing between two agreements by ether-token transducer.
According to the layered protocol of International Organization for Standardization about computer network, reference model such as Fig. 4 of network system interconnection represent.
Any two Computer I and II in the comprehensive service network for cable television network system, by digital terminal adapter DTA (I) and the DTA (II) of oneself, carry out data communication (two-way) each other according to Ethernet protocol, and the transmission of bi-directional data is to abide by token protocol on the CATV cable between DTA (I) and the DTA (II).Transducer is finished two conversions between the agreement on the data link layer.The token protocol physical layer of DTA comprises radio modem RF Modem.
The digital terminal adapter is finished following function:
1. present networked computer more than 80 percent all is to carry out the ether agreement, and DTA is fit to this requirement that computer links to each other with cable television network just.In addition, no matter which kind of hardware and software platform (PC, minicomputer, large-scale computer, Dos, Windows, Unix etc.) can both enter comprehensive service network for cable television smoothly as long as possess the standard ether interface.In other words, most computers can both insert comprehensive service network for cable television in the world.
Owing to be connected the Broadband Computer Networks of the online computer formation of integrated service be and base band Ethernet network compatibility, thereby can prolong with a large amount of prior aries and standard, make existing many products, even do not add modification ground and just can on the cable TV service network, obtain to use, insert as the Internet net etc.
2. when number of users increases,, cause the decline of the actual data transfer rate of Ethernet because collision postpones.Because the DTA operation with two kinds of agreements of Taihe county token, when a plurality of ether users send simultaneously, has only the user who obtains token to collide and to produce thus the shortcoming that postpones thereby eliminate really to its data of online transmission.
The token protocol of DTA is to transmit bus association instrument with reference to IEEE802.4 international standard token, and it is simplified, and revises and replenishes, and adopt the suitable dsp chip of price that can buy at home to finish its protocol function.What should propose especially has a following tripartite surface function:
3. in token handing-over and data transmission, increased functions of retransmission; Aspect the loop reorganization, do not take to be recombined into ring, and adopt the new control method of going into to encircle, therefore increased antijamming capability.
4. the user can be provided with the transmission range of network according to actual needs, thereby enlarges the coverage of network.Maximum covering radius can reach more than 1,000 kilometer, surpasses the coverage of a city CATV net out and away.
5. site address coding is increased to 16 by 8, so site address is increased to 65535 by former 255, has surpassed data user's quantity of present access CATV net fully.Because the number of users that the computer network set up in the frequency band of a limitation holds has increased, in fact reduce the taking of other frequency band, therefore improve utilization to frequency resource.
It is to be noted at last, for the front end system on comprehensive service network for cable television, adopt the intelligent front end system of the base band data regenerative of our company exploitation, therefore the minimizing system is to the requirement of signal to noise ratio, increase is to the antijamming capability of burst, reduction is to the requirement of data indicator terminal, thereby can simplify terminal equipment, reduces equipment manufacturing cost.
B. network adapter
The system construction drawing of network adapter as shown in Figure 5 and Figure 6.Wherein dsp chip TMS320C52 finishes the major function of DTA network adapter software and hardware, divides from function, can divide four fatware modules:
1. token protocol master control modules A CM
ACM is the main functional modules of IEEE802.4 Token-Passing Bus token protocol, is mainly used in access control, goes into ring and moves back ring etc. comprising exchange, the user of the formation of token ring, token.Be the transmission of suitable CATV net and the characteristics of Ethernet interface, this module is done suitable simplification and modification to the IEEE802.4 agreement.
2. Ethernet control module ETM
ETM finishes realized the control of Ethernet protocol controller by the UM9007 chip, UM9007 is the isa bus Ethernet controller, ETM is by the parameter setting to its internal state and control register, simultaneously, control data is received at token, (that is ether is sent out to send out the data buffer zone, receive the data buffer zone, it is the data storage RAM of TMS320) with the exchange that receives in the UM9007 chip between data buffering ring and the transmission buffering area, and to ACM, IFM, RxM and TxM provide the interface Control Parameter, thereby realize the transmitting-receiving control of Ethernet, for DTA provides ether interface.
3. token is received and dispatched control module RxM ﹠amp; TxM
These two modules receive or send by interrupt mode by Frame and control frame after the FPGA processing, and the frame that receives is judged, the judgement of the judgement of CRC check position, Frame and the control frame that adopts comprising FCS, the judgement of noise etc. are put corresponding sign then and are notified IFM or ACM respectively.
4. data interface module IFM
IFM carries out the transmission of token frame from reception data field (being positioned at the frame buffer of TM320) to token reception data buffer (that is ether transmission data buffer zone) that is received by RxM.On the contrary, by the control of IFM and ACM, token data frame to be sent carries out rightabout transmission.Similar other module, IFM also coordinates ETM, ACM, RxM ﹠amp simultaneously; Interface Control Parameter between the TxM.
Except that microprocessor chip TMS320 finishes four big functions of above network adapter, still have other interface unit to finish other function of network adapter:
5. receiving frame processor
Receiving frame processor adopting scale programmable logic device (FPCA) the chip XC3042PC84 of network adapter as shown in Figure 3 mainly finishes the processing capacity of receiving frame.The sending part branch comprises parallel/serial conversion, additional frame starting and ending sign, additional frame checking sequence FCS, scrambling processing and differential coding.Receiving unit comprises digital phase-locked loop, scramble process, identification frame starting and ending sign, calculates FCS result and serial/parallel conversion (seeing Fig. 5 for details).
6. encryption equipment
Encryption equipment adopts single-chip microcomputer PIC54, and communicates by letter with TMS320 by serial ports.The characteristics of utilizing PIC54 to encrypt are stored some data through specific coding therein.PIC54 only receives the packet that TMS320 meets certain data structure, could revise or export data wherein, guarantees the normal running of TMS320.
7. ether is received and dispatched interface
The ether computer that divides thick, cablet and two kinds of confessions of twisted-pair feeder to be connected on the DTA is selected for use.
8.RS232 interface
Being equipped with RS232 interface commonly used, is communicating by letter between main frame and the TMS320 for convenience, and the user can be on the PC platform like this, changes that TMS320 internal processes parameter is provided with and some parameter of modification modulator-demodulator.
Two functions that will illustrate at last:
9. ether-token transducer
Translation function with two agreements of Taihe county token is finished jointly by four software modules among the TMS320.
10. network coverage
The scope of effectively covering of former Ethernet has only hundreds of rice, and along with the distance lengthening, the actual state of circuit has not been reacted in carrier sense and collision detection.Because DTA adopts ether-token to transmit the transmission means of bus, has solved the problem (with reference to A.4 explanation) at the long distance running Ethernet.
C. radio modem (RF Modem)
Fig. 7 represents the fundamental diagram of radio modem.Be connected into the online computer of cable TV data to be sent,, nonreturn to zero code be transformed into differential code, be sent to modulator coding and two-way differential phase keying (DPSK) modulation again, form the DPSK modulation signal by network adapter.Provide the data feedback channel carrier wave by last horizontal lock local oscillator.Satisfy the cable TV neighbour by the carrier signal behind the band pass filter and keep pouring in defeated characteristic.Through power amplification, be sent to channel-splitting filter again.Channel-splitting filter is actually provides unidirectional up transmission to upward signal.Downstream signal is sent to preamplifier through channel-splitting filter.After the mixing, obtain the intermediate-freuqncy signal of 36MHZ, after the adjacent frequency of band pass filter filtering signal, deliver to demodulator.Demodulator adopts the delay coherent demodulation technology to demodulate baseband digital signal, delivers to network adapter through the baseband digital signal of low-pass filtering, shaping output Transistor-Transistor Logic level again and handles.
In cable TV optical fiber/coaxial cable distribution system, for realizing transmitted in both directions, the coaxial cable transmission band is divided the uplink and downlink frequency range.Dividing mode has high, medium and low partitioning scheme, as shown in Figure 8.In optical fiber, be to adopt two optical fiber to realize two-way passback, and the radio frequency electric interfaces of radio modem is wired coaxial cable of looking.The channeling of radio modem on coaxial cable meets the low segmentation standard of China's cable TV.
The key technical indexes of radio modem as shown in Table 1.Its key technology that adopts has following several respects:
Table one radio modem the key technical indexes
| Index | Parameter | Remarks |
| Incoming frequency | 47～958MHz | |
| Incoming signal level | -3～20dbmV | |
| Output frequency | 5～30MHz | |
| Output signal level | 40-60dbmV | |
| Data rate | 2.5Mb/s | |
| The output signal bandwidth | 5MHz | |
| The output signal carrier-to-noise ratio | ＞70dB | |
| The output signal adjacent channel suppresses | ＞55dBc | |
| The demodulating data error rate | ＞10 -8 | ?C/N＞25dB |
| Power supply/power consumption | 220V?AC50Hz/10W | |
| Volume (length * wide * height) | 270×160×58mm 3 |
1. two-phase difference position keying (DPSK) is adopted in modulation, and demodulation is adopted and postponed relevant difference.
2.DPSK modulator is realized with application-specific integrated circuit (ASIC).
3. radio modem adopts surface mount elements in a large number, thereby the reduction equipment volume reduces system power dissipation, increases reliability.
4. the uplink and downlink channel all adopts PHASE-LOCKED LOOP PLL TECHNIQUE to realize frequency agility respectively, therefore, improves the record activity of system.
5. because demodulator uses quick combined synchronous demodulation technique to solve fast demodulation problem to bursty data.
6. adopt the automatic gain control of great dynamic range to solve the error code problem that different terminals sends and incoming level is inconsistent and cause.
Claims (4)
1. a comprehensive service network for cable television digital terminal adapter is characterized in that: be made up of radio modem and network adapter; Wherein:
(1) network adapter comprises ether interface, ether-token transducer, parts such as token interface and receiving frame processor;
(2) radio modem comprises radio-frequency modulator and radio-frequency (RF) demodulator.
2. comprehensive service network for cable television digital terminal adapter according to claim 1 is characterized in that: (1) receiving frame processor is scale programmable logic device fpga chip XC3042PC84, mainly finishes the receiving frame processing capacity; The sending part branch comprises parallel/serial conversion, additional frame starting and ending sign, and additional frame checking sequence FCS, scrambling processing and differential coding, receiving unit comprises digital phase-locked loop, scramble process, identification frame starting and ending sign calculates FCS result and serial/parallel conversion;
(2) major function of network adapter software and hardware (containing the translation function with two agreements of Taihe county token) is to be made of jointly four software modules among the microprocessor TMS320, comprise four funtion parts, token protocol master control modules A CM, data interface module IFM, Ethernet control module ETM, token transmitting-receiving control module RxM and TxM;
(3) ether interface is two kinds of thick, Thin cable or twisted-pair feeders.
3. be equipped with netting index word terminal adapter according to claim 1, the comprehensive clothes of 2 described cable TVs, it is characterized in that: the ether interface of network adapter is connected with the computer ether interface, ether-token transducer is connected with token interface with ether interface, token interface is connected with the receiving frame processor, the receiving frame processor is connected with the signal input part of radio-frequency modulator and the signal output part of radio-frequency (RF) demodulator respectively, and the output of radio-frequency modulator and the signal input part of radio-frequency (RF) demodulator are connected with wire cable television network CATV.
4. comprehensive service network for cable television digital terminal adapter according to claim 1 and 2 is characterized in that: the model of finishing the microprocessor of network adapter software and hardware major function can be TMS320 series or AM186EM series.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN96209993U CN2247402Y (en) | 1996-04-10 | 1996-04-10 | Digital terminal adapter for cable television comprehensive service network |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN96209993U CN2247402Y (en) | 1996-04-10 | 1996-04-10 | Digital terminal adapter for cable television comprehensive service network |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2247402Y true CN2247402Y (en) | 1997-02-12 |
Family
ID=33893456
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN96209993U Expired - Fee Related CN2247402Y (en) | 1996-04-10 | 1996-04-10 | Digital terminal adapter for cable television comprehensive service network |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2247402Y (en) |
-
1996
- 1996-04-10 CN CN96209993U patent/CN2247402Y/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C57 | Notification of unclear or unknown address | ||
| DD01 | Delivery of document by public notice |
Addressee: Wang Guoce Document name: Notification of Termination of Patent Right |
|
| 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 |