CN105611324A - Analog high-definition video transmission system - Google Patents
Analog high-definition video transmission system Download PDFInfo
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- CN105611324A CN105611324A CN201511016222.3A CN201511016222A CN105611324A CN 105611324 A CN105611324 A CN 105611324A CN 201511016222 A CN201511016222 A CN 201511016222A CN 105611324 A CN105611324 A CN 105611324A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/4302—Content synchronisation processes, e.g. decoder synchronisation
- H04N21/4305—Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
- H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
- H04N21/238—Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams
- H04N21/2383—Channel coding or modulation of digital bit-stream, e.g. QPSK modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/41—Structure of client; Structure of client peripherals
- H04N21/426—Internal components of the client ; Characteristics thereof
- H04N21/42676—Internal components of the client ; Characteristics thereof for modulating an analogue carrier signal to encode digital information or demodulating it to decode digital information, e.g. ADSL or cable modem
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/4302—Content synchronisation processes, e.g. decoder synchronisation
- H04N21/4307—Synchronising the rendering of multiple content streams or additional data on devices, e.g. synchronisation of audio on a mobile phone with the video output on the TV screen
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/438—Interfacing the downstream path of the transmission network originating from a server, e.g. retrieving MPEG packets from an IP network
- H04N21/4382—Demodulation or channel decoding, e.g. QPSK demodulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client
- H04N21/61—Network physical structure; Signal processing
- H04N21/6106—Network physical structure; Signal processing specially adapted to the downstream path of the transmission network
- H04N21/6118—Network physical structure; Signal processing specially adapted to the downstream path of the transmission network involving cable transmission, e.g. using a cable modem
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client
- H04N21/61—Network physical structure; Signal processing
- H04N21/6156—Network physical structure; Signal processing specially adapted to the upstream path of the transmission network
- H04N21/6168—Network physical structure; Signal processing specially adapted to the upstream path of the transmission network involving cable transmission, e.g. using a cable modem
Abstract
The invention relates to an analog high-definition video transmission system. Mainly, a digital signal is embedded into an analog high-definition system, and line/field blanks and idle time/frequency spaces, which are not used by the analog high-definition system, are utilized to carry out transmission, and thus, downward compatibility can be achieved. Meanwhile, by using a digital channel estimation technology, an amplitude-frequency and phase-frequency response of a coaxial cable/twisted-pair channel can be accurately estimated, and thus, compared with the prior art of estimating a channel response only according to measurement on amplitude-frequency responses of a small number of frequency points of the channel, channel estimation accuracy of the analog high-definition video transmission system provided by the invention is obviously improved, so that adaptability to different channels and particularly poor cables is promoted.
Description
Technical field
The invention belongs to field of video transmission, relate to a kind of for transmit the biography of videl signal on coaxial cableCommunication system, refers to one transmission of high-definition analog video signal and number on coaxial cable or twisted-pair feeder especiallyThe device of word signal.
Background technology
At present, the Analogvideotransmission based on coaxial cable is widely used in all kinds of closed-circuit TV monitoring systemsApplication. Because CVBS standard the earliest can not meet the demand that HD video transmits, HD-SDIBe used in a long time the standard as coaxial HD video transmission. But its very high data transfer rateTo limit transmission range, conventionally to have had two approach in order addressing this problem: the first is by digital high-definitionVideo compress, changing down to be to reduce its requirement to channel by this, for example all kinds of based on MJPEG,The IP video camera of AVC or HEVC, IP-based monitoring system can obtain height flexibility withSecurity, but compression can lose image quality and cause postponing, and simultaneously IP system can not compatible original CCTVSystem, installation and debugging are also more complicated. Another approach is the expansion based on CVBS technology, logicalCross the simulation high-definition signal that transmits high bandwidth more in coaxial channel to break through CVBS standard for imageThe restriction of resolution ratio. Its analogue transmission characteristic can be put down it in the time meeting with noise jamming or poor cableThereby downhill race level has promoted the availability of system under extreme case, and can utilize based on CVBS'sThe original wiring of CCTV system, installation and debugging are also more simple, and this makes the user can be more level and smoothUpgrade to high-definition monitoring system from SD monitoring system.
Two above-mentioned paths have all obtained swift and violent development in recent years, especially at home, and simulation high definitionStandard is widely applied as aCVI, HDCVI, TVI and AHD.
Because current video camera/DVR (digital VTR, digitalvideorecorder) is numeralSystem, therefore simulates HD video system and need to digital video be converted to analog signal at transmitting terminal,And at receiving terminal again by its digitlization. Because transmit stage is analog signal, but simulation HD videoSystem does not ensure that the videl signal of the videl signal that receives and transmission is in full accord, therefore its forSome application exists shortcoming. Moreover video camera end may have some digital informations to transfer toDVR end, the HD digital image of for example capturing at video camera end is wished transmission that can be completely harmlessHold to preserve important view data to DVR, current simulation high definition transmission system cannot meet thisOne requirement. Current simulation HD video system only has the up-downgoing digital signalling of several kilobaudsChannel, only can support the application such as menu configuration and cradle head control, for the primary of video camera end is providedResolution ratio is captured, and Digital Audio Transmission provides the digital compression video subcode after coding to spread even simultaneouslyDefeated incapability is substantially power.
On the other hand, existing simulation high definition transmission system need to be supported long line transmission, and distance can reachEven longer to 300～500m, and long cable has brought larger signal attenuation and dispersion. For this reasonIn the transmission of simulation high definition, conventionally adopt analog balanced and pre-emphasis technique to compensate channel distortion. ButThe prerequisite that channel distortion can be compensated is that the characteristic of channel is carried out to correct estimation. As HDCVI passes throughThe characteristic of channel is estimated in the contrast of the amplitude difference to colorburst and brightness synchronous head. TVI is at frameBlanking interval has used the sinusoidal signal of a line transmission assigned frequency and level to determine that channel is in this frequencyDecay situation. But these measures all the amplitude-frequency response of remeasurement channel on characteristic frequency, andResponse characteristic that can not complete acquisition channel therefore also needs according to cable model channel in applicationCharacteristic is further estimated work. But in actual applications the model of coaxial cable or twisted-pair feeder,Quality and installation environment difference great disparity, the amplitude-frequency response of a set of cable model and a small amount of several frequenciesCan not describe accurately the actual channel characteristic of applied environment, this makes the effect of channel compensation can notReach expection, especially easily occur at poor cable that online smear, fuzzy, ghost image and contrast declineEtc. various image quality loss.
Summary of the invention
Main purpose of the present invention is providing a kind of simulation high-resolution video transfer system, and it can solve existing mouldIntend the problem that HD video standard does not have high-speed figure up channel, solve for complicated on-the-spot simultaneouslyWiring environment is especially compared with the adjustment of long and second-rate cable.
To make aforementioned simulation high-resolution video transfer system for reaching the technical way that aforementioned object takesThere is a transmitting terminal and a receiving terminal; Wherein
Described transmitting terminal comprises:
One video processing module is that to be converted to a grating suitable by a HD digital vision signal of inputThe bright signal of order scanning;
One signal modulation/mixing module is that compound looking modulated and be mixed into described reception bright signalFrequently signal;
One first digital processing element, in order to modulate the data signal of an input;
One adder, in order to by data signal, described composite video signal after modulation and one synchronous/Control signal obtains a composite video data signal after mixing;
One preemphasis module, in order to carry out described composite video data signal obtaining again after preemphasisClose video signal;
One DAC module, in order to be converted into an analog signal by described composite video data signal;
One circuit driver module, in order to amplify described analog signal send out;
Described receiving terminal comprises:
One analog front-end module, amplifies the described analog signal receiving and preliminary compensate for channel decay;
One ADC module, quantizes to obtain one again according to analog signal sampling described in a timing informationClose video signal;
One synchronous detection module, by obtaining described synchronizing information in described composite video data signal;
One video signal separation module, receives described composite video data signal and described synchronous letterBreath, and from composite video data signal, isolate described data signal and described composite video signal;
One second digital processing element, in order to receive described data signal (2), described in producing after treatmentLocating information, a channel information and a data signal (3); And described data signal (3) is carried out to information source solutionCode, to obtain the data signal that inputs to described the first digital processing element;
One time domain equalizing demodulation separation module, by the described channel information, the described data signal (3) that receiveAnd described composite video signal completes time domain equalization and operation is offset in active, and complete demodulation and divideFrom obtaining described bright signal;
One video processing module, goes forward side by side line raster counter-scanning to be converted in order to receive described bright signalDescribed HD digital vision signal.
Utilize above-mentioned technology simulating HD video system embedment data signal, the row/field that utilizes it not useTransmit in blanking and idle time/frequency space, and can accomplish backward compatible. And owing to using numeralChannel estimation technique, can estimate amplitude-frequency and the phase-frequency response of coaxial cable/twisted-pair feeder channel accurately, comparesPrior art only can be estimated channel response, channel of the present invention according to the amplitude-frequency response of measuring a small amount of frequency of channelEstimated accuracy increases significantly, thereby has promoted the adaptive capacity to the especially poor cable of different channels.
Brief description of the drawings
Fig. 1 is the block diagram of a typical simulation high-resolution video transfer system.
Fig. 2 is the block diagram of simulation high-resolution video transfer system of the present invention.
Fig. 3 is the frame assumption diagram of a typical simulation high-resolution video transfer system.
Fig. 4 is signal time/frequency performance plot of a typical simulation high-resolution video transfer system.
Fig. 5 is the spectrogram of the present invention while making data signal and composite video signal share identical frequency band.
Detailed description of the invention
Below coordinate preferred embodiment graphic and of the present invention, further set forth the present invention predetermined for reachingThe technological means that goal of the invention is taked.
Fig. 1 is the framework of a typical simulation high definition transmission system. Comprise that a transmitting terminal 10 and connectsReceiving end 20; Wherein, described transmitting terminal 10 comprises a video processing module 11, a signal modulation/mixModule 12, an adder 13, a preemphasis module 14, a DAC module 15 and a circuit driveModule 16; Described video processing module 11 is accepted the HD digital vision signal from outside input,Be converted into the bright signal 0 of raster order scanning, blanking interval is inserted in this stage and completes conventionally.Described signal modulation/mixing module 12 is accepted described bright signal 0, by its modulation and be mixed into one compoundVidel signal 0. Described synchronize with one/control signal of composite video signal 0 is added by described adder 13After enter described preemphasis module 14, described preemphasis module 14 is amplified the high frequency division of the signal of inputAmount is with compensate for channel decay and signal after treatment is delivered to described DAC module 15. Described DAC mouldPiece 15 receives the digital high-definition videl signal of input and is converted into an analog signal 0, described simulationSignal 0 is transferred into described circuit driver module 16, and described circuit driver module 16 is by the mould of inputAnalog signal 0 amplifies and sends by coaxial cable or twisted-pair feeder.
Described receiving terminal 20 comprises an analog front-end module 21, an ADC module 22, a synchronously detectionModule 23, a signal separation/demodulation module 24 and a video processing module 25; Wherein, described simulationAfter front-end module 21 amplifies the signal from coaxial cable or twisted-pair feeder and compensate for channel decays, obtainObtain an analog signal 1 and be sent to described ADC module 22. Described ADC module 22 receives simulation letterNumber 1 and be converted to a composite video signal 1. Described synchronous detection module 23 is from described multipleClose in videl signal 1 and extract synchronizing signal, comprise the synchronizing signal of row/field and chrominance carrier. InstituteStating signal separation/demodulation module 24, to utilize described synchronizing signal to isolate from composite video signal 1 brightDegree and carrier chrominance signal are also carried out demodulation and are obtained a bright signal 1. Bright signal 1 after demodulation enters instituteState video processing module 25 and carry out grating counter-scanning, be converted to high-definition digital video signal r. LogicalCross said system and just pass through coaxial cable or twisted-pair feeder from transmitting terminal 10 by a HD digital signalBe sent to receiving terminal 20.
Fig. 2 has used the simulation high definition transmission system structure chart after the present invention, basic framework and Fig. 1Identical. Difference be in: transmitting terminal 10 of the present invention further comprises one first of processing digital signalDigital processing element 17, in the present embodiment, described the first digital processing element comprises an information source codingModule 171, a digital modulation module 172: described receiving terminal 20 comprises analog front-end module 21,ADC module 22, synchronous detection module 23 1 video signal separation modules 26, a time domain are equalWeighing apparatus demodulation separation module 27, a video processing module 25 and one second digital processing element 28: described inThe second digital processing element 28 comprises a digital timing recovery module 281, a digital signal receiver282, a channel estimation module 283 and a source coding module 284.
The present invention is identical with primal system to the processing of HD digital vision signal, described transmitting terminal 10Video processing module 11 accept the HD digital vision signal from outside input, be converted intoOne bright signal 0 of raster order scanning, blanking interval is inserted in this stage and completes conventionally. Described signalModulation mixing module 12 is accepted bright signal 0, by its modulation and be mixed into a composite video signal 0,Common simulation high definition transmission system is used base band transmission in luminance signal at present, in carrier chrominance signalAfter using AM to be modulated to subcarrier, transmit, but the present invention does not limit this.
Described data signal is carried out information source coding by described information source coding module 171, and described information source is compiledThe operations such as code module 171 includes but not limited to scrambler, interweaves, the insertion of Error Correction of Coding training sequence obtainDigital signaling zero, described digital signaling zero enters described digital modulation module 172, described Digital Modulation mouldPiece 172 can but do not limit and adopt AM (amplitude modulation(PAM)) or OFDM (OFDM) etc.Mode is modulated described digital signaling zero and is obtained data signal 1, can be, but not limited to make in modulated processTo adjust the frequency spectrum 1 of described data signal 1, make its coupling by the technology such as digital filtering and shaping pulseIn the spectral characteristic of described composite video signal 0, so that make full use of the transmission letter of optimizing into the latterRoad, and avoid emc issue. Data signal 1 after modulation and composite video signal 0 and oneSynchronously/control signal obtains a composite video digital signaling zero after mixing. Described composite video data signal0 enters described preemphasis module 13 by obtaining a composite video data signal 1 after preemphasis, described inComposite video data signal 1 is converted into an analog signal 0 through described DAC module 14, and logicalCrossing described circuit driver module 15 amplifies and sends out.
The analog front-end module 21 of receiving terminal 20 is amplified the signal from coaxial cable or twisted-pair feederAnd acquisition analog signal 1 is sent to described ADC module 22 after preliminary compensate for channel decay, for suitableAnswer different channels, the gain of described analog front-end module 21 and amplitude-frequency response can be adjusted conventionally, butConcrete adjustment mode and Strategy and effectiveness are in close relations, all may be different in each specific implementation,The present invention does not limit this, repeats no more. Described ADC module 22 is according to described data signalThe digital timing recovery module 281 of processing unit 28 provides a timing information so that analog signal 1 is carried outSample and quantize to obtain a composite video data signal 2, described ADC module 22 can adopt fixingSampling instant is sampled and the mode of implementing resampling realizes specifying moment sampling, also can adopt variableThe mode of sampling instant realizes specifying moment sampling, also can adopt other modes to realize the variable momentSampling, the present invention does not limit this.
Described composite video data signal 2 is sent into described synchronous detection module 23, described synchronous detection mouldPiece 23 obtains synchronizing information from its input signal, can include but not limited to frame synchronization, row synchronous andColour synchronisation. Described composite video data signal 2 and synchronizing information are also sent to described video signalSeparation module 26, described video signal separation module 26 divides from composite video data signal 2From going out data signal 2 and composite video signal 1. Data signal 2 is sent to described numeral letter simultaneouslyNumber receiver 282, channel estimation module 283 and digital timing recovery module 281. Digital signal receptionMachine 282 can adopt but be not limited to equilibrium/amplification/demodulate/decode/judgement the data signal 2 of input is enteredRow is processed, and therefrom replys out data signal 3, and data signal 3 is well estimating of data signal b normallyMeter. This data signal 3 is sent to source coding module 284, channel estimation module 283 and numeralTiming recovers module 281. Digital timing recovery module 281 receiving digital signals 2 and data signal 3,And use the algorithm of digital timing recovery module 281 therefrom to obtain sampling timing information, and by its transmissionTo ADC module 22. Described channel estimation module 283 receiving digital signals 2 and data signal 3, andUtilize it to estimate channel, estimate that the channel information obtaining offers time domain equalization demodulation separation module 27.Described time domain equalization demodulation separation module 27 utilizes channel information and data signal 3 and composite video newsNumber 1 completes time domain equalization and initiatively offsets operation, from composite video signal 1, eliminates fading channelAnd the intersymbol interference of dispersion introducing, and portion that may be residual in the separation process of video/data signalPoint data signal, and complete demodulation and separate that to obtain brightness/chroma signal be luminance chrominance signal 1. ?In concrete enforcement, this equilibrium and demodulating process can exchange sequences or better in conjunction with carrying out obtainingPerformance, the present invention does not limit this. Bright signal 1 after demodulation enters described Video processingModule 25 is carried out grating counter-scanning, is converted to fine definition numerical digit vision signal r. Data signal 3 is logicalCross described source coding module 284 and carry out source coding acquisition data signal r. So HD digital is lookedFrequently signal is just sent to receiving terminal 20 from transmitting terminal 10 by coaxial cable or twisted-pair feeder, simultaneously numeralSignal is also sent to receiving terminal 20 from transmitting terminal 10 by same coaxial cable or twisted-pair feeder.
Fig. 3 is the frame assumption diagram of a typical simulation high-resolution video transfer system, and Fig. 4 is an allusion quotationSignal time/frequency characteristic of the simulation high-resolution video transfer system of type. Existing simulation high definition transmission system allHave similar framework: brightness is used base band transmission, colourity is used AM modulation, and synchronization mechanism adoptsThe level synchronization of similar NTSC, colour synchronisation adopts colorburst directly to transmit by the head of being expert atChrominance carrier is realized synchronous. Main distinction of each simulation high definition transmission system be frame structure andSubcarrier frequency. Some simulation high definition transmission system separates completely as brightness/chroma frequency range in HDCVI,And some system there will be overlapping as both frequency ranges in aCVI. The present invention does not make restriction to this.Especially, due to the raster scanning characteristic of analog video signal, its main concentration of energy is attached at line frequencyClosely, therefore in Analogvideotransmission standard, the frequency range of colourity can be overlapped with brightness, both useFrequency range interval 1/2 line frequency (as aCVI and NTSC) or 1/4 line frequency (as PAL), and at receiving terminal20 use comb filtering to complete light tone separates.
The present invention utilizes region idle in time/frequency space of simulation high definition transmission to transmit data signal. CanTo select retaining original synchronization mechanism, include but not limited to go synchronous/field synchronization and colour synchronisation, withGuarantee that system can keep primary characteristic or the compatibility that further keeps down. Or can useSimultaneous techniques based on digital communication substitutes original synchronization mechanism, thereby utilizes original synchronization mechanism to account forWith time/frequency domain space, further promoting transmission rate or reduce bandwidth occupancy and extend transmission distance.Compare original simulation high-resolution video transfer system, the present invention has increased digital channel in signal transmission.Because digital channel itself can be, but not limited to by various based on data-aided timing recovery technology etc.Mode provides carrier synchronization, sample-synchronous and frame/row synchronous, and therefore synchronous detection module 23 can be in order toDetect synchronizing signal by the mode identical with original simulation high-resolution video transfer system, also can by withThe above digital form obtains synchronizing information, or can adopt the mode of both combinations, the present invention coupleThis does not limit.
Further, as Fig. 5 the present invention can be, but not limited to by Digital Modulation by data signal 1 withComposite video signal 0 shared band, and use comb filtering and active cancellation technology to complete both dividingFrom. Compare the isolation technics of tradition based on comb filtering, the active of interpolation offset can be more effective fromIn composite video signal 0, eliminate residual digital signal components, the interference of avoiding the latter to produce.
The present invention, by embed data signal in simulation HD video system, realizes and is keeping simulation highThe ability of Mbps to 10Mbps stages of digital channel is provided under the prerequisite of clear video system advantage, is enough to fullFoot high-definition image is captured transmission, and high-quality digital audio is transmitted the even requirement of digital video transmission.
The data signal embedding can utilize row/field blanking that simulation HD video system do not use andTransmit in idle time/frequency space, therefore can accomplish backward compatible. Use digital channel to estimate simultaneouslyMeter technology can be estimated amplitude-frequency and the phase-frequency response of coaxial cable/twisted-pair feeder channel accurately, compares existingTechnology only can be estimated channel response according to the amplitude-frequency response of measuring a small amount of frequency of channel, provided by the inventionPrecision of channel estimation increases significantly, thereby has promoted fitting the especially poor cable of different channelsShould be able to power. Introduce time domain equalization technology and can effectively eliminate hangover and the circuit resistance that long line transmission is introducedThe image deflects such as anti-reflection of not mating introducing. It is dry that introducing active cancellation technology can solve data signalDisturb the problem of the analog signal of closing on time/frequency, thereby can further compress guarantor between the twoProtect interval, improve efficiency of transmission and promote simulation video quality.
With a specific embodiment, apparatus structure of the present invention is described, the present embodiment design objective is for meetingThe transmission of 720p25 simulation high-definition signal. Brightness analog bandwidth 16MHz, total transmission bandwidth 24MHz.Numeral up channel peak bandwidth 10Mbps.
First HD digital vision signal enters video processing module 11, turns according to raster scan orderFor time-domain signal, and insert blanking interval and be converted to bright signal, comprise luminance component respectively and colourity is dividedAmount. Then luminance component enters a low pass filter bandwidth is limited, and avoids interference colourity letterNumber, chromatic component is carrying out adopting AM orthogonal modulation to the subcarrier of specifying after LPF,In the present embodiment, subcarrier frequency is 21MHz, brightness bandwidth 16MHz, chrominance bandwidth 3MHz.
In the present embodiment, digital channel uses 0～23MHz, and first data signal carries out Error Correction of Coding, insertsEnter synchronizing sequence and carry out subsequently scrambler. Above process is completed by information source coding module 17. Then carry out netAfter trellis coding, use a PAM8 modulators modulate, then use Pulse shaped filter to output frequentlySpectrum is carried out shaping, makes signal spectrum can approach the frequency spectrum of composite video signal, simplifies receiving circuitDesign and avoid emc issue. If need higher digital channel bandwidth, also can selectBy the modulation system of high-order more and can add the technology such as OFDM, the present invention does not make restriction to this.
In the present embodiment, frame synchronization is realized by the synchronizing sequence embedding in data signal, does not therefore needWant extra synchronous/control signal, only have colorburst to retain. Composite video signal 0 and numeral letterNumber 1 and colorburst be added and obtain composite digital video signals 0, digital composite through adder 13Vision signal 0 inputs to preemphasis module 14 and obtains composite digital video signal 1 and export DAC mould toPiece 15 is converted to analog signal 0 and exports circuit driver module 16 to drive coaxial cable or twisted-pair feederChannel.
The analog front-end module 21 of receiving terminal 20 is amplified the signal from coaxial cable or twisted-pair feederAnd after preliminary compensate for channel decay, acquisition analog signal 1 is sent to ADC module 22. ADC module 22The timing information providing according to digital timing recovery module 281 carries out sample quantization to analog signal 1 and obtainsObtain composite video data signal 2. In the present embodiment, ADC module 22 is used 256 phase places phase-lockedRing is realized variable moment sampling, and the clock phase that it provides according to digital timing recovery module 281 generatesClock phase also carries out sample quantization. Composite video data signal 2 is sent into synchronous detection module 23, afterPerson detects synchronizing sequence according to the characteristic of synchronizing sequence from input signal, in the present embodiment, and synchronous orderRow use a subset of grid coding to encode so that receiving terminal detects. Composite video numeral letterNumbers 2 and synchronizing information be sent to video signal separation module 26, described video signal separatesModule 26 determines that according to timing information region isolates data signal 2 from composite video data signal 2And composite video signal 1. Data signal 2 is sent to digital signal receiver 282, channel estimating mouldPiece 283 and digital timing recovery module 281. Digital signal receiver 282 in the present embodiment usesInterconnected decoding equalizer completes decoding and the equalization operation of grid coding, and adjudicates generating digital signal 3.Data signal 3 and data signal 2 are sent to source coding module 284, channel estimation module 283And digital timing recovery module 281. The auxiliary numeral of digital timing recovery module 281 usage datas is determinedTime recovery algorithms from data signal 3 and data signal 2, recover optimum sampling timing, this guarantees simultaneouslyThe sampling clock of transmitting terminal 10 can recover at receiving terminal 20 accurately, therefore receiving terminal 20 timeClock is synchronizeed with transmitting terminal 10, and this has significantly simplified the demand synchronous to frame/row. Described channel estimating mouldPiece 283 receiving digital signals 2 and data signal 3, and utilize it to estimate channel response, estimate to obtainChannel information offer time domain equalization demodulation separation module 27. Time domain equalization demodulation separation module 27Calculate the tap coefficient of transversal filter according to channel response, and use transversal filter from composite videoIn signal 1, eliminate the intersymbol interference that fading channel and dispersion are introduced, then use digital filtering to separateThe brightness of bright signal 1 and chroma signal component, and its chroma signal component is carried out to synchronous demodulation.The local carrier that demodulation is used is from colorburst. Bright signal 1 after demodulation enters Video processingModule 25 is carried out grating counter-scanning, is converted to fine definition numerical digit vision signal r. Data signal 3 is logicalCross source coding module 284 and carry out source coding acquisition data signal r. So HD digital video letterNumber be just sent to receiving terminal 20 from transmitting terminal 10 by coaxial cable or twisted-pair feeder, simultaneously data signalAlso be sent to receiving terminal 20 from transmitting terminal 10 by same coaxial cable or twisted-pair feeder.
For the conversion of simplification and BT.1120 or HDMI standard, in the present embodiment, frame structure adopt withEvery frame 750 every trades 22.5kHz frequently that the above two are consistent, each video line 1650 is sampled. Each videoFrame comprises 720 effectively row, comprises the video line of simulation HD video signal. Data signal is usedDuring remaining video is capable 25, all the other 5 row retain to down channel and use. Data signal is in blank lines1650 samplings that interior use is whole, in effectively going, analog video uses 1280 samplings, numeralChannel uses 200 samplings, and residue sampling retains to colorburst, synchronizing sequence and protection interval.Therefore digital up channel can transmit (1650*25+200*720) in each frame* 3=771750bit, peak transmission rate can reach 13.8Mbps. Consider Error Correction of Coding, signaling and synchronize orderThe bandwidth that row take, more than effectively transmission bandwidth can reach 10Mbps.
The above is only preferred embodiment of the present invention, not the present invention is done to any pro forma limitSystem, although the present invention discloses as above with preferred embodiment, but be not in order to limit the present invention, any ripeKnow professional and technical personnel, not departing from the scope of technical solution of the present invention, when utilizing above-mentioned announcementTechnology contents make a little change or be modified to the equivalent embodiment of equivalent variations, be not depart from this in every caseThe content of bright technical scheme, any simple modification of above embodiment being done according to technical spirit of the present invention,Equivalent variations and modification, all still belong in the scope of technical solution of the present invention.
Claims (9)
1. a simulation high-resolution video transfer system, has a transmitting terminal and a receiving terminal; Its feature existsIn:
Described transmitting terminal comprises:
One video processing module is that to be converted to a grating suitable by a HD digital vision signal of inputThe bright signal of order scanning;
One signal modulation/mixing module is that compound looking modulated and be mixed into described reception bright signalFrequently signal;
One first digital processing element, in order to modulate the data signal of an input;
One adder, in order to by data signal, described composite video signal after modulation and one synchronous/Control signal obtains a composite video data signal after mixing;
One preemphasis module, in order to carry out described composite video data signal obtaining again after preemphasisClose video signal;
One DAC module, in order to be converted into an analog signal by described composite video data signal;
One circuit driver module, in order to amplify described analog signal send out;
Described receiving terminal comprises:
One analog front-end module, amplifies the described analog signal receiving and preliminary compensate for channel decay;
One ADC module, quantizes to obtain one again according to a timing information to described analog signal samplingClose video signal;
One synchronous detection module, by obtaining described synchronizing information in described composite video data signal;
One video signal separation module, receives described composite video data signal and described synchronous letterBreath, and from composite video data signal, isolate a data signal (2) and described composite video newsNumber;
One second digital processing element, in order to receive described data signal (2), described in producing after treatmentTiming information, a channel information and a data signal (3); And described data signal (3) is carried out to information source solutionCode, to obtain the data signal that inputs to described the first digital processing element;
One time domain equalizing demodulation separation module, by the described channel information, the described data signal (3) that receiveAnd described composite video signal completes time domain equalization and operation is offset in active, and complete demodulation and divideFrom obtaining described bright signal;
One video processing module, goes forward side by side line raster counter-scanning to be converted in order to receive described bright signalDescribed HD digital vision signal.
2. simulate according to claim 1 high-resolution video transfer system, it is characterized in that: described firstDigital processing element comprises:
One information source coding module is that the data signal of input is carried out to information source coding;
One digital modulation module is that the described data signal through Signal coding is modulated.
3. simulate according to claim 2 high-resolution video transfer system, it is characterized in that: described information sourceCoding module comprises scrambler, interweaves, Error Correction of Coding training sequence inserts.
4. simulate according to claim 1 high-resolution video transfer system, it is characterized in that: described secondDigital processing element comprises: a digital timing recovery module, a digital signal receiver, a channel are estimatedMeter module and a source coding module; Wherein
Described in described video signal separation module is isolated from described composite video data signalIt is extensive that data signal (2) is sent to described digital signal receiver, channel estimation module and digital timing simultaneouslyMultiple module; Described digital signal receiver is replied out described data signal from described data signal (2)(3) it is fixed that, described data signal (3) is sent to described source coding module, channel estimation module and numeralShi Huifu module;
Described digital timing recovery module receives described data signal (2) and data signal (3), utilizes algorithmTherefrom obtain described timing information, and be sent to described ADC module;
Described channel estimation module receives described data signal (2) and data signal (3), utilizes and estimates channelObtain described channel information and offer described time domain equalization demodulation separation module;
Described time domain equalization demodulation separation module utilize described channel information and described data signal (3) withAnd composite video signal completes time domain equalization and initiatively offsets operation;
Described source coding module is carried out source coding to described data signal (3) and is inputed to institute to obtainState the data signal of the first digital processing element.
5. simulate according to claim 4 high-resolution video transfer system, it is characterized in that: described numeralSignal receiver uses an interconnected decoding equalizer to complete decoding and the equalization operation of grid coding, and sentencesCertainly generate described data signal (3).
6. simulate according to claim 4 high-resolution video transfer system, it is characterized in that: described ADCThe sampling timing that module provides according to described digital timing recovery module is to described analog signal samplingQuantize.
7. simulate according to claim 4 high-resolution video transfer system, it is characterized in that: be described synchronousDetection module according to the characteristic of synchronizing sequence from input signal, detect synchronizing sequence-.
8. simulate according to claim 4 high-resolution video transfer system, it is characterized in that: described numeralTiming recovers the auxiliary digital timing recovery algorithm of module usage data from described data signal (3) and numberIn word signal (2), recover optimum sampling timing.
9. simulate according to claim 4 high-resolution video transfer system, it is characterized in that: described time domainEqualizing demodulation separation module calculates the tap coefficient of a transversal filter according to channel response, and uses instituteStating transversal filter, from described composite video signal, to eliminate the intersymbol that fading channel and dispersion introduce dryDisturb.
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