Background technology
Image and voice signal by TV station's broadcast, after digital compression and digital modulation, form digital television signal, transmit through modes such as satellite, terrestrial wireless broadcast or wire cables, after the Digital Television reception, restore original image and sound accompaniment by digital demodulation and digital video-audio decoding processing.Its process adopts digital technology to handle, thereby the loss of signal is little, and reception is good.
In Digital Television, adopt the bidirectional transfer of information technology, increased interaction capabilities, make people obtain various network services according to the demand of oneself, comprise new business such as video request program, shopping online, remote teaching, tele-medicine, make television set become genuine information household appliances.Can predict, following development of television direction is exactly that direction towards demand mode develops.Digital Television can also provide other service, comprises data transmission, broadcast videography, service on net etc.The user can use the stock exchange of TV reality, information inquiry, surfing on the net etc., makes TV be endowed new purposes, has expanded the function of TV, TV has been become the window of interchange from the window of sealing.
Bi-directional digital television is the trend of following radio and television system development, technically, and bi-directional digital television function complexity, interface is various, cloth version complexity in order to keep the stable of performance and to reduce cost, just needs high integration, high-speed, low-power consumption, chip cheaply.Multiple function is integrated on the chip piece, can improves machine performance, reduce power consumption and area of chip simultaneously.
At present, the chip that occurs on the market, integrated level is not high mostly, function is few, needs the coupling of polylith chip could satisfy the multi-functional demand of bi-directional digital television, makes machine performance decline, power consumption height, cost height.
Summary of the invention
The purpose of this utility model provides a kind of high integration, high-speed, low-power consumption, bidirectional multifunctional chip cheaply.
The purpose of this utility model is achieved through the following technical solutions:
Bidirectional multifunctional chip of the present utility model comprises processor module, also comprises modulator block, demodulator module and on-chip bus, wherein,
Described processor module is connected with modulator block, demodulator module, and receives outside cable TV signal by demodulator module; Send signal by modulator block to the outside, realize two-way communication with the outside;
Described processor module comprises cable TV international standard DOCSIS signal processing unit, is used for the outside cable TV signal of the DOCSIS standard that receives by demodulator module is handled; And local signal handled, send to the outside by modulator block handling the local signal that obtains based on the DOCSIS standard;
Described processor module is connected with on-chip bus, and connects a plurality of external interfaces by on-chip bus.
Described modulator block can be connected with the bi-directional digital television tuner with demodulator module, and can be connected with cable TV network by the bi-directional digital television tuner, in order to realize and TV station's two-way interactive signal.
Described demodulator module comprises analog to digital conversion circuit, channel demodulation circuit, channel decoding circuit, received outside cable TV signal is handled through analog to digital conversion circuit, channel demodulation circuit, channel decoding circuit successively, and the signal that will handle inputs to processor module;
Processor can pass to source decoder with the signal of handling, and by source decoder signal is converted into sound and/or picture signal.
Described demodulator module also comprises clock recovery circuitry, the filter circuit that roll-offs, channel equalization circuit, carrier recovery circuit and byte of sync circuit.
Described channel decoding circuit comprises deconvolution interleave circuit, RS decoding circuit, removes the randomization circuit.
Described modulator block comprises chnnel coding circuit, modulation circuit, D/A converting circuit, and local signal is handled, and sent to the outside through chnnel coding circuit, modulation circuit, D/A converting circuit successively.
Also comprise the Ethernet information process unit,
Described a plurality of external interface comprises internet interface;
Described Ethernet information process unit is connected with internet interface by on-chip bus, is used to realize the function with the Internet two-way interactive information.
Described a plurality of external interface comprises memory interface, is used to connect static memory and high speed flash memory, realizes local signal is kept in static and dynamic flash memory.
Described a plurality of external interface comprises two-wire control bus interface, is connected respectively with source decoder with the bi-directional digital television tuner, is used to realize the control to bi-directional digital television tuner and source decoder.
Described a plurality of external interface comprises USB interface, can connect multiple USB device.
The technical scheme that is provided by above-mentioned the utility model as can be seen, bidirectional multifunctional chip described in the utility model, owing to comprise processor module, modulator block, demodulator module and on-chip bus, processor module is connected with modulator device module and demodulator module, and receive outside cable TV signal and send signal to the outside by modulator block, demodulator module, can realize two-way communication with the outside;
Processor module also is connected with on-chip bus, and connects a plurality of external interfaces by on-chip bus, can manage and control a plurality of external equipments;
Owing to also comprise the Ethernet information process unit, can realize function again with the Internet two-way interactive information.
The utility model is integrated in multiple function on the chip piece, can improve machine performance, reduces power consumption and area of chip simultaneously, is mainly used in the communication of cable TV bidirectional multifunctional.
Embodiment
The preferable specific embodiment of bidirectional multifunctional chip of the present utility model as shown in Figure 1, comprises processor module, modulator block, demodulator module and on-chip bus, wherein,
Described processor module is connected with modulator block, demodulator module, and receives outside cable TV signal, sends signal by modulator block to the outside by demodulator module, realizes two-way communication with the outside;
Described processor module comprises DOCSIS (cable TV international standard) signal processing unit, is used for the outside cable TV signal of the DOCSIS standard that receives by demodulator module is handled; And local signal handled, send to the outside by modulator block handling the local signal that obtains based on the DOCSIS standard;
Described processor module is connected with on-chip bus, and connects a plurality of external interfaces by on-chip bus.
Described modulator block can be connected with two-way DTV (Digital Television) tuner with demodulator module, and can be connected with cable TV network by the bi-directional digital television tuner, in order to realize and TV station's two-way interactive signal.The bi-directional digital television tuner also has the function of two merit devices except that having critical functions such as tuner amplification, frequency conversion, channel selection, can be between this diji and TV station two-way sending and receiving information.Can be configured in the television set, also can be placed in the set-top box.
As shown in Figure 3, described demodulator module comprises analog to digital conversion circuit, channel demodulation circuit, channel decoding circuit, received outside cable TV signal is handled through analog to digital conversion circuit, channel demodulation circuit, channel decoding circuit successively, and the signal that will handle inputs to processor processing.
Wherein, channel decoding circuit comprises deconvolution interleave circuit, RS decoding circuit, removes the randomization circuit.
As shown in Figure 2, the bidirectional multifunctional chip can be connected with the DTV source decoder, is used for the outside cable TV signal that receives and handled is converted to sound or picture signal.Finish the transmission to local user's downstream signal by TV station.
As shown in Figure 3, described demodulator module also comprises clock recovery circuitry, the filter circuit that roll-offs, channel equalization circuit, carrier recovery circuit and byte of sync circuit, respectively downstream signal is done corresponding processing.
Below the conveying flow of downstream signal is done and is simply described:
DTV signal downlink flow process: two-way DTV tuner amplifies frequency conversion to the radio television signal that receives, transfer intermediate-freuqncy signal to by high-frequency signal, deliver to the input of bidirectional multifunctional chip, at first carry out analog/digital conversion, carry out demodulation then, clock recovery, filtering, distortion is compensated (channel equalization), the conversion of carrier wave recovery and byte and symbol, and the coding of Channel Transmission process decoded, described decoding comprises deinterleaving, RS decodes and goes randomization, digital signal is finished in recovery, and the signal after the processing send the DTV source decoder to be converted to sound or picture signal.The DTV source decoder here must meet the signal standards of TV station's emission, can meet MPEG (the moving image Committee of Experts) standard, or the AVS of China Ministry of Information Industry (video/audio compression) standard.
Carry out under the state of two-way interactive information local user and TV station, downstream signal will be handled or the queue order wait acknowledge through processor module, send the DTV source decoder to be converted to sound or picture signal then; Under the state that the local user only directly televiews, downstream signal directly send the DTV source decoder to be converted to sound or picture signal after can being handled by demodulator module.
In the above-mentioned flow process, the effect of clock recovery circuitry is: make receive-transmit system keep synchronous in time.In digital communication system, for receiving terminal, the actual symbol rate that transmitting terminal sent, with transmitting terminal all be unknown to the propagation delay of receiving terminal, in order to obtain original transmission information, just must from received signal, derive symbol regularly, thereby obtain correct symbol sampler.
The effect of channel equalization circuit is: for linear time-variant channel, noise and echo reflection have produced stronger interference to signal, cause amplitude and phase distortion, therefore need to adopt channel equalization or circuit to mend the way that reward is proofreaied and correct, from channel, extract useful signal, thereby reach the influence that suppresses to offset noise and echo reflection, improve antijamming capability.
The effect of carrier recovery circuit is: set up and the synchronous reference carrier of signal carrier.Because the frequency of local crystal oscillator and the uncertain deviation of signal center frequency have caused regularly recovering the back symbol and had certain phase deviation, the purpose that carrier wave recovers is exactly to detect deviate by phase-locked loop, thereby eliminates deviation, realizes carrier synchronization.
As shown in Figure 4, described modulator block comprises chnnel coding circuit, modulation circuit, D/A converting circuit, local signal is handled through chnnel coding circuit, modulation circuit, D/A converting circuit successively, and export to two-way DTV tuner, the signal that to be handled by two-way DTV tuner sends to cable TV station, finishes the transmission of upward signal.Comprise that also byte hints obliquely at circuit, channel pre-equalization circuit, the filter circuit that roll-offs to symbol, respectively to there being the local user to do corresponding processing to the upward signal of TV station.
Wherein, the chnnel coding circuit comprises convolutional interleave circuit, RS coding circuit and randomization circuit.
Below the upflow of DTV signal is done and is simply described:
DTV signal uplink flow process: local user's command signal (is used keyboard, mode such as remote controller or voice is imported) deliver to the bidirectional multifunctional chip internal, at first local signal is handled by the DOCSIS signal processing unit in the processor module, to handle the signal that obtains by modulator block then and carry out chnnel coding based on the DOCSIS standard, comprise randomization, RS encodes and interweaves, carry out byte then to sign map, compensation (equilibrium), filtering, modulation, arrive the digital-to-analog conversion at last, signal is transferred to program center or zone center, wait acknowledge by two-way DTV tuner.
Described a plurality of external interface also comprises memory interface, is used to connect random asccess memory and high speed flash memory, realizes local signal is kept in static and dynamic flash memory.Local user's command signal mainly is linked into the bidirectional multifunctional chip by memory interface.
Carry out in the process of two-way information interaction local user and TV station, the main effect of processor module is to coordinate and the agreement related task, as TCP/IP, 802.3 agreements etc.; Allotment information is transmitted, and the signal flow of commander's memory and interface also has the guiding of isolated by filtration network signal and each subpath of DTV signal etc.
Bidirectional multifunctional chip of the present utility model, also comprise the Ethernet information process unit, comprise internet interface in described a plurality of external interface, the Ethernet information process unit is connected with internet interface by on-chip bus, and by internet interface realization function of surfing the Net, communication function etc., the local user can realize two-way interactive information with the Internet.Carry out in local user and the Internet under the state of two-way interactive online, the signal that meets MPEG or AVS standard can be delivered to the DTV source decoder by memory interface and be converted to sound or picture signal.
Described a plurality of external interface comprises two-wire control bus interface, and this is a cable TV internal interface, is connected respectively with source decoder with the bi-directional digital television tuner, is used to realize the control to bi-directional digital television tuner and DTV source decoder.
Described a plurality of external interface also comprises spare interface, is used to realize that the outside of some other needs connects, and can also comprise expansion interfaces such as some other string and interface, such as comprising USB interface, is used to connect multiple USB device etc.
Bidirectional multifunctional chip of the present utility model is connected with the bi-directional digital television tuner, can realize the two-way interactive function with cable TV station; With Internet connection, can realize online and communication function with the Internet two-way interactive information; Being connected with source decoder, then finishing the bi-directional digital television receiver, also is multi-functional information terminal, realizes seeing the multiple function of TV, communication and function of surfing the Net.
The above; it only is the preferable embodiment of the utility model; but protection range of the present utility model is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the utility model discloses; the variation that can expect easily or replacement all should be encompassed within the protection range of the present utility model.