CN1204897A - Transmitting system and method - Google Patents
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- CN1204897A CN1204897A CN 98106313 CN98106313A CN1204897A CN 1204897 A CN1204897 A CN 1204897A CN 98106313 CN98106313 CN 98106313 CN 98106313 A CN98106313 A CN 98106313A CN 1204897 A CN1204897 A CN 1204897A
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Abstract
A transmitting system for transmitting a RF signal includes a data receiving device for receiving a date signal containing coded audio data and video data, wherein, the signal includes a first clock signal; a data recovery device for recovering the first clock signal from the data signal; a data randomization device for changing the data sequence of the data signal; a coder for coding the randomized data signal based on the predetermined coding method; a trellis coder for trellis coding the coded data signal.
Description
The present invention is to be target with the circuit that transmits simulation and signal numeral and system, is target with electronic circuit and the system that produces and transmit the TV signal of numeral especially.
The coml TV signal has adopted the TSC-system formula to broadcast for many years.Constantly occupied along with the appearance of high definition TV and radio-frequency spectrum, determined television broadcasting station that the radio hookup of NTSC signal and Digital Television (following usefulness " DTV " expression) signal will be provided, made a large amount of mounted NTSC receivers and the new DTV that installs receive function and appreciate same broadcasting simultaneously.Like this, radio hookup will comprise that television channel by separately is with the radio hookup of the same program of two kinds of different systems codings.The two all is decided to be the bandwidth of 6 megahertzes NTSC and DTV channel.
The radio hookup of two kinds of standards of NTSC and DTV will comprise uses two different channels.Because the frequency spectrum that provides to additional channel is very limited, has proposed additional channel and be positioned near other existing channel.There, NTSC and DTV signal the two all be to be launched by adjacent channel.There is the problem of a considerable co-channel interference in there, the NTSC and the mutual interference mutually of DTV signal of there.If the signal of delivery DTV and/or NTSC waveform is not to be accurately positioned and not remain within its appointed channel bandwidth, the interference problem between the adjacent channel will worsen.
As shown in fig. 1, in the DTV system that is proposed, the signal with video and voice data can be sent out from a signal source, for example delivers to the radio-frequency transmissions scene from a television stadio, this scene may with the studio not at same place.In a such system, the data-signal of video and audio frequency may adopt the conventional communication technology to be launched or to be sent to radio frequency/launch site, for example microwave link from the studio.Sort signal is commonly called the transmission signal, and it will comprise the clock of data and data, or independent clock or utilize the clock coding of self to encode as Manchester (Manchester).Routinely, radio frequency/transmitter will utilize data clock with in order to be used for restored data in transmitter.Like this, if the emission layer clock is inaccurate or drift, inaccurate effect will have influence on signal, and this signal is broadcasted away from transmitter the most at last.Keep accurately that broadcasting frequency is significant, the frequency error that causes at the inaccurate clock of emission layer (common studio) may highly must make us being difficult to accepting.As described below, in example of the present invention, by being used for the system of radio frequency/launch site, can exempt or the offset data clock in inaccuracy, make the signal broadcast away have stable frequency component.
The problem that co-channel and crossover channel disturbs may be, is part at least owing to be used in the signal of generation or emission video and/or audio frequency, causes to the difference the clock of their emission from their generation.By using the basis of a public clock here, can reduce or eliminate such interference as each different piece of broadcast system that illustrates and signal generation.
The objective of the invention is for the TV signal that produces a numeral provides a circuit and system, generation and/or maintenance based on the component of frequency in this signal are very accurately.
Another purpose is that the inaccuracy for compensation and/or adjustment data clock provides a circuit and system before broadcast television signal, and a circuit and a system that does not need synchronous handshake procedure to move on two asynchronous clocks is provided.
Further purpose is in order to increase a pilot signal to TV signal and to carry out mistake in TV signal a circuit and the system of providing is provided.
One further purpose be that transmission for TV provides a circuit and system.Data-signal wherein has its dependence to the frequency of the data rate travel of numeral, and frequency is adapted to its demarcation condition, and is provided for the circuit and the system of lattice code and is used for the multiband antenna of television system.
The present invention includes an emission system that is used to launch a radiofrequency signal, comprising:
(a) be used to receive a device that contains the data-signal of the voice data of having encoded and video data, wherein said signal comprises one first clock signal;
(b) be used for from the data-restoring device of this this first clock signal of data-signal recovery;
(c) data randomizer is used for changing the order of these data-signal data;
(d) encoder is encoded to this randomized data-signal according to a kind of specified coding scheme;
(e) a lattice shape (trellis) encoder, to this encoded data signals carry out lattice shape (trellis) coding;
(f) pulse shaping device is used for constraining within the fixing bandwidth carrying out lattice shape (trellis) encoded data signals;
(g) pilot signal device is used for a pilot signal is joined this bound data-signal;
(h) be used for upconvert device with this a bound data-signal and pilot signal upconvert to a channel frequency;
(i) be used to amplify the amplifier installation of this bound data-signal and pilot signal; And
(j) be used to launch the broadcaster of all signals that amplified.
To be illustrated the present invention by the example reference accompanying drawing now, wherein:
Fig. 1 is a functional block diagram of the digital television system of prior art;
Fig. 2 is the functional block diagram of a circuit in radio-frequency (RF) emission system;
Fig. 3 is a functional block diagram of radio-frequency (RF) emission system;
Fig. 4 is the amplitude-frequency characteristic curve chart of a DTV signal that is produced;
Fig. 5 is the functional block diagram of a generating and communicating advanced television circuit;
Fig. 6 is the functional block diagram of an interleave circuit of previous technology;
Fig. 7 is the functional block diagram of the buffer circuits that interweaves;
Fig. 8 is the functional block diagram of a speed conversion circuit;
Fig. 9 is the functional block diagram of first embodiment of the control circuit of a lattice shape (trellis) encoder;
Figure 10 is the functional block diagram of first embodiment of trellis encoder;
Figure 11 is the functional block diagram of second embodiment of trellis encoder;
Figure 12 represent a corrected in theory nonlinear amplifier and with the amplitude of its coherent signal and a series of curve charts of frequency relation;
Figure 13 represents a series of curve charts of frequency domain of a series of curve charts of Figure 12;
Figure 14 is the phase place related with the input and output circuit of a typical nonlinear amplifier and the curve chart of amplitude response;
Figure 15 represents a series of curve charts of the frequency domain of a typical corrected nonlinear amplifier and the signal relevant with it;
Figure 16 is a functional block diagram of an improved Correction circuit according to an aspect of the present invention;
Figure 17 is a functional block diagram especially for second embodiment of the Correction circuit of Figure 16 of an intermediate frequency compensating circuit;
Figure 18 is a functional block diagram of utilizing the scene, studio of an aspect;
Figure 19 is the on-the-spot functional block diagram of transmitter of utilizing one aspect of the present invention.
Calcspar according to a basic DTV system 100 of digital television standard that issues September 16 nineteen ninety-five of AdvancedTelevision Standards Committee of U.S. government (" ATSC ") regulation is made up of three part institutes, as shown in fig. 1, comprise a source code and compression section 102, service multiplexer and hop 104 and a radio frequency/emission system 106.Source code and compression section 102 receive a vision signal 108 and an audio signal 110, and respectively these signals are encoded, and become the data flow of numeral.Coding can comprise known the bit rate "flop-out" method and the compress technique that are applicable to video and voice data.
Video behind Fig. 1 presentation code and voice data are supplied with service multiplexer and hop 104 with the data-signal 112 and the control data signal 114 of replenishing.Supplementary signal 112 and control signal 114 can comprise control data, access control data with good conditionsi and the data relevant with audio frequency and Video service, the Attach Title data of for example closing.Usually can compress vision signal with MPEG-2 video flowing grammer, and audio signal be compressed with audio compression (AC-3) standard of numeral.
In service multiplexer and hop 104, compressed data flow can be divided into all packets of information and can add the similar device that is used to discern each bag or bag.In this process, video data stream, the bag of audio stream and the data flow of replenishing can become an independent data flow through multiplexed (multiplex).The data of having packed can be used video, and the data-signal packing and the multiplexed MPEG-2 transmission system of audio frequency and the broadcast system that is used for numeral are transmitted.
At radio frequency/radiating portion 106, the data quilt of having packed is by channel coding and modulation.Channel encoder 120 can be revised data flow and add additional information, this additional information can be used for allowing receiver re-construct data from the signal that receives, and this signal is the influence that is subjected to common transmission interference source.
The signal that modulating part 122 utilizes the data diffluence modulation of numeral to send.In the DTV standard, modulation can be adopted a 8VSB (residual sideband) modulation scheme.Modulated signal can be exaggerated and deliver to antenna 124, is used for broadcasting in the mode of routine.
Fig. 2 represents that a radio frequency/emission system can receive data and clock signal 10 from the hop shown in the system of Fig. 1.Data and clock signal can be delivered to data recovery circuit 202, and this circuit is extracted data from the standard of transmission, and if necessary also can be from same signal the extracted data clock.Data-signal can be delivered to randomizer 204, and this generator changes the order of data in the scope of data flow according to the DTV standard.Randomizer 204 can be operated according to the generator multinomial, also can operate according to pseudo-random binary sequence.
Can deliver to Reed-Solomon (ReedSolomon) encoder 206 from the signal of randomizer 204 outputs, this encoder adopts the Reed-Solomon coding techniques that packets of information is provided, and this packets of information is to encode according to the known i.e. method of deciding of the receiver of signal.Encoded bag is sent to an interpolater 208, and this interpolater is carried out a convolutional interleave according to a set scheme on data.Reed-Solomon encoder 206 writes a data buffer (not shown) with the data rate of transport layer, and interleaver 208 is with the data rate read data of emission layer.This does not need synchronous shake hands and can move on two asynchronous clocks with regard to the allowance system.
Can deliver to lattice shape (trellis) encoder 210 from the signal of interleaver 208 outputs.In a DTV system, trellis encoder is used the lattice shape code of 2/3 speed that has a uncoded position.In the DTV system, utilize one 1/2 rate convolutional code, an input position is encoded as two carry-out bits, and encode in advance in other input position.According to the characteristic of DTV, the signaling waveform that uses with trellis code is the conformation of one 8 grades (3) one dimensions.Can be sent to a synchronous insertion circuit 212 from the signal of trellis encoder 210 outputs, the synchronizing signal of data segment and the synchronizing signal of data field are inserted in the appropriate location of this circuit in the data flow of numeral.
Can deliver to a Nyquist (Nyquist) filter 214 and the bandwidth (DTV system to standard be 6 megahertzes) of the spectrum limitations of the data flow behind the coding from the data flow of the numeral of synchronous insertion circuit 212 outputs in emission system.The function of filtering in the present invention comprises following step: the interpolation and the upconvert of (1) signal; (2) for non-linear corrected signal; (3) in addition balanced with a sef-adapting filter to the defective of existing frequency response; (4) to down-conversion and storage digital phantom.
Through nyquist filter 214 (with relevant shaping pulse) afterwards, can add a pilot tone.After the shaping pulse by nyquist filter, utilize the insertion of the insertion pilot signal of pilot signal to be kept in the circuit.The digital signal that the quilt that nyquist filter 214 provides is added with pilot tone is become an analog signal by a digital-to-analog converter 216, and is sent to one of input of an intermediate frequency mixer 30.Another input signal of intermediate frequency mixer 30 is the carrier frequency of an intermediate frequency, and it is from an IF-FRE phase-locked loop circuit 218.The intermediate-freuqncy signal that intermediate frequency mixer produced is sent to an intermediate-frequency circuit 40, and this circuit carries out filtering and output signal delivered to one of input of mixer channel 50 intermediate-freuqncy signal.Another input of channel frequency mixer 50 is a channel frequency that gets from a special radio frequency (UHF) phase-locked loop 170.In one embodiment of the invention, IF-FRE phase-locked loop 218 and special RF Phase-Lock Loop 70 can produce their signals separately from a public clock reference 190.The clock signal that clock reference 190 can make it is based on an external signal (EXT REF) or the clock signal that produces based on this machine, or the data of coming free exciter to receive.
Can deliver to a band pass filter 60 in a conventional way from the signal of channel frequency mixer 50 outputs, remove to produce a signal through filtering, this signal is amplified fully and supplies with antenna 220 is used for broadcasting.The signal that Fig. 2 represents to be input to data recovery circuit 202 can be the data and the clock signal of separating, or signal that the embeds clock application of Manchester's code (for example from).The clock ReSet Circuit can use the phase-locked loop of a standard to go to be locked in and be embedded on the clock that receives in the data.In case clock is restored, it just can be used for the timing of drive system.Data recovery circuit 202 can also comprise a frame synchronizer, and the signal that is used for sending at (Fig. 1's) translator unit is to the synchronizing signal location, and a data flow that receives is aligned to the usefulness of byte for processing.
Fig. 2 explanation receives the data byte of coming to each from translator unit in the DTV of standard system, the Reed-Solomon encoder requires doubly taking advantage of and 20 times XOR (XOR) addition of 20 apotypes (modula) 256.When adopting high data rate in the DTV system, coding needs a processor can finish 9,700 ten thousand operations each second.In one embodiment of the invention, the Reed-Solomon encoder connects same dictionary (look-up) table and can realize obtaining so high data rate in a programmable gate array in territory.
Nyquist filter 214 can be used as have-α-coefficient be a root of 0.1152-liter-cosine filter uses.This filter also can be used as a finite impulse response filter and realizes.In a preferred embodiment, this filter is a complex filter of handling the residual sideband function.
Fig. 2 and Fig. 3 represent (wherein public parts have public reference number), in one embodiment of the invention, the frequency mixer 30 of Fig. 1,50 with relevant phase-locked loop 218,70 can realize in a circuit, modulator 20 parts of the circuit of Fig. 1 are the single square of Fig. 3 by abbreviation in this circuit, modulator 20.A data-signal 10 that is sent to modulator 20 produces a clock signal 302 and an encoded data signal 21 (being the standard of simulation).Because clock signal 302 and encoded data signal 21 all produce since a digital data stream, the final frequency of these signals be directly and digital data rates proportional.If these signals are used to produce the signal that will launch, transmit just by the frequency lock of data source.Under a certain situation, emission layer be away from transport layer (may be under common control even), sends broadcasting station based on the signal of distant place data source and be under these circumstances the characteristic of the desired strictness in broadcasting station that can not go to reach such in the control of broadcasting frequency.In addition, administrative authority, resembling the desired interference problem for co-channel or adjacent channel of FCC is irrealizable to any frequency compensation that transmits not changing original data rate.In one aspect of the invention, tranmitting frequency to digital data the dependence of speed by circuit for eliminating shown in Figure 3.This circuit also provides one to be used to be provided with needed accurate frequency compensated device.
Fig. 3 and Fig. 4 describe the modulator 20 of the analog-modulated frequency signal that produces a coded data 21.In the DTV of standard signal, encoded data signal 21 can be for example to DTV illustrated be in one 8 residual sideband (VSB) standard.Encoded data signal 21 can be any other modulation signal, NTSC signal for example, a FM signal, amplitude-modulated signal and/or a monolateral band (SSB) signal etc.Under the situation of one 8 residual sideband (VSB) signal, signal will be just like form represented among Fig. 4, and this signal has the centre frequency of a nominal at 10.76 megahertzes and a VSB pilot signal nominal is arranged at 8.06 megahertzes in the figure.Usually, encoded data signal 21 is that this frequency is significantly less than the frequency of the signal that will broadcast on a frequency, and essential upconvert is to the frequency of broadcasting.Encoded data signal 21 at first is sent to a frequency changer 30 (for example frequency mixer) and goes to produce an intermediate-freuqncy signal 31.In one embodiment of the invention, the signal that a nominal frequency is arranged is 54.76 megahertzes is sent to frequency changer and goes to produce intermediate-freuqncy signal 31.This intermediate-freuqncy signal 31 is sent to a second frequency converter 50 (for example frequency mixer) and goes to make the intermediate-freuqncy signal upconvert to desired channel frequency then.Can be sent to a load from the signal of second frequency converter 50 output after being exaggerated as requested gets on.
Be used for the frequency of encoded data signal upconvert is got from a reference frequency 190 by frequency changer 30, as being revised by data clock 302.Like this, encoded data signal is the dependence cancellation of the frequency of speed to digital data, and the frequency of signal is corrected to its nominal state or near normal condition.
Fig. 3 expresses digital modulator 20, and this modulator also produces numerical data clock 302, and this clock is used to a programmable frequency divider 180, and it becomes 1 to 1 ratio with the pilot carrier frequency or the carrier frequency of the modulator 20 of numeral.Like this, for a DTV system, from the signal 181 of frequency divider 180 output normally at 8.06 megahertzes.Signal 181 is sent to one the 3rd frequency changer 150.
Be in operation, the frequency of NCO110 is controlled by reference frequency 190.Reference frequency can be a (not shown) that this machine produces or that receive from an external circuit or device.Reference frequency can be delivered to other similar circuit, and the signal that makes a plurality of numerals produce can be by frequency lock at same benchmark.
NCO120 should be able to provide enough frequency resolutions to arrive intermediate-freuqncy signal 31 desired degree.In the 4th frequency changer 130, deduct the output of NCO120 from the output of VCO94.BPF140 is used for filtering any unwanted output from the 4th frequency changer 130.
The 3rd frequency changer 150 that is in operation deducts the output signal of programmable frequency divider 180 from the output of a BPF140.The 2nd BPF170 is from any unwanted output of the 3rd frequency changer 150 eliminations, and gives second programmable frequency divider 98 this difference frequency.For the nominal signal state, second programmable frequency divider 98 is to be configured to have identical output frequency with reference divider 80.The output of these two frequency dividers 98,90 is supplied to phase detectors 90.Like this, the phase difference between the output of phase detectors 90 and its two inputs is proportional and be sent to loop filter 92.This loop filter 92 is the output transform of phase detectors 90 one and the proportional voltage of phase difference, and gives VCO94 this voltage.As a result, VCO94 in reference frequency, rather than is locked in the speed of original numeral by frequency lock.
Move under a non-nominal data rate with an input data signal, the circuit for eliminating of Fig. 3 the influence of non-nominal rate.For example, if the clock rate and the nominal value of the data 10 that arrive differ △, the frequency of signal 302 will equal 10.76 megahertzes and add △, and the frequency of signal 181 will equal 8.06 megahertzes and add △.△ propagates by the reference frequency component, and finally by VCO94, makes that the signal that is used in 30 upconvert of first frequency converter also is to depart from the △ value from nominal value.Because data-signal also departs from the △ value at signal 21, first frequency converter 30 cuts this two △ components, allows signal 31 not have departing from of △.
Standard at DTV transmits in the rules, and synchronizing signal (byte) is not the number of a uniqueness.So, if having data any 8 in succession the position identical with this sync byte, will provide the synchronous indication of a mistake.Native system utilizes a confidence counter to overcome the influence of this false sync.Confidence counter is counted continuously to the number of sync byte.With reference to figure 2, if data recovery circuit 202 can not expectably detect a sync byte, the confidence level of genlocing just descends, and confidence counter is by decrement.All do not detect a sync byte if some frames take place in data flow at a certain specific byte location, frame synchronizer loses genlocing with indication mechanism, and automatically begins a new frame search and catch operation.
Fig. 5 represents one embodiment of the present of invention, utilize the frame and the bit synchronizer of confidence counter can receive the data (serial data) that receive with a serial form from transport layer, serial data can be transformed to parallel form (resembling one 8 parallel data word) and supply with a synchronizing indicator 752 by a serial-to-parallel converter 750.Synchronizing indicator is made comparisons data word and predetermined synchronization character and is indicated whether found signal is provided for confidence counter 754 synchronously.If expectably find synchronizing signal, confidence counter 754 is with regard to increment counter, if still can not find as scheduled, counter 754 is with regard to decrement counter.A synchronizing signal is expected from frame of the synchronization character that is detected at last exactly.Like this, since last synchronous detecting, a modulo counter 758 is just counted the number of words that runs into, and starts confidence counter 754 on the synchronous word of expectation.If confidence counter 754 reaches a predetermined numerical value, during this frame just is considered to be in synchronously, and there is the signal of a genlocing to be sent to other parts in the circuit and/or to be shown to the Systems Operator.If confidence counter 754 is reduced to zero, just be considered to lose synchronously, cause the disappearance of synchronous locking signal and resetting of modulo counter 758, thereby restart to search for synchronizing signal (promptly beginning once new frame search and acquisition mode).
Fig. 5 represents that modulo counter 758 provides mould 8 countings of the serial bit that enters serial-to-parallel converter 750.Like this, converter 750 just can with the aiming at of the remainder holding position of sync detection circuit.At each mould counting finally, data word is when offering the data randomizer, and whether other parts that also offer synchronizing indicator data randomizer and circuit can utilize synchronous locking signal to go the determination data byte effective.Confidence counter can be modified easily and obtain the confidence level that synchronous locking signal obtains, and higher usually confidence level needs long synchronous detecting time.In addition, losing of genlocing need not wait until always that confidence counter turns back to zero (promptly can require the synchronous detecting of 5 successes to obtain locking, as long as but have the failure of three continuous subsynchronous detections just may cause synchronous losing).Similarly, successful synchronous detecting can bind for several times, make in case after synchronously locked, confidence counter not again increment to greater than the numerical value of locking (if still do not find as scheduled one synchronously will decrement).
Lose input synchronously after startup the time, the confidence counter circuit is set to begin one and searches the pattern of obtaining.In this acquisition mode, bits of serial data is delivered to serial-to-parallel converter 750 serially by clock, and this converter can adopt one 8 digit buffer form.So,, check the appearance of 8 data word sync byte in each clock cycle.If detect sync byte, the count enable position just is set, and circuit enters one and puts the letter test pattern.Whenever the count enable position is set, mould 1504 counters begin counting, until next 1504 (each is 188 8 a word or a frame) are sent out away.During this time, detected once more synchronously, whether the process of looking at repeats.If sync byte do not occur, the count enable position just is reset, and acquisition mode is just restarted.If detect the predetermined number of a continuous frame synchronization, synchronous locking signal just is set, and circuit enters a frame lock pattern.After this, normal operation beginning and frame synchronization are constantly detected and are gone to guarantee reliable emission.If do not find the synchronizing signal of frame in a predetermined frame number, circuit will be switched, and turns back to acquisition mode, restarts whole process.
Notice that the confidence counter circuit promptly can be used to launch the DTV signal, also can be used to receive and show in the receiver of DTV or other digital frame signal.As previously discussed, such receiver just is faced with a same foundation and keeps the problem of frame synchronization, and circuit of the present invention also will be useful to such receiver.
In one aspect of the invention, be used for the frequency of the signal of transport layer, by the interleaver (INTERLEAVER) of data can make with emission layer in signal frequency irrelevant.Make data interlacing with a kind of method in the prior art, this is well-known, and data frequency is reformed in the method.For example Fig. 7 represents to have from emission layer a signal of the data of 19.39 megahertz speed, is provided for a Reed-Solomon encoder usually and is used for encoding in the mode of routine.The data of leaving Reed-Solomon encoder 550 will be used to supply with microprocessor 552, and this processor will interweave to coded data, and it is usually in the mode of a pulse train, offer the device buffer 554 of retiming with speed arbitrarily.The device buffer 554 of retiming can delay usually and fills from the data of the pulse string mode of microprocessor and with particular rate the output signal according to its clock control, the normally speed of 10.76 megahertzes of standard.The clock signal that offers 10.76 megahertzes of the device buffer 554 of retiming in prior art system is usually produced by the PLL556 of 19.39 megahertz clocks (usually being to draw from data) driving from one.
In another aspect of the present invention, the pulse string mode microprocessor of prior art can utilize a suitable buffer that interweaves to delete.Fig. 7 represents a Reed Suo Luomeng encoder, it can receive data on the frequency of the transport layer of 19.39 megahertzes, and provide coded data to a data interleaver buffer 208, these data are read out with the speed of one the 43.04 megahertz buffer 208 from interleaver, and supply with trellis encoder 210, this trellis encoder is with the speed output lattice code data of 10.76 megahertzes related with emission layer.Notice that the clock of 43.04 megahertzes of speed conversion can use trellis encoder 210, and therefore can be for carrying out lattice code from the usefulness of interleaver buffer 208 extracted data as timing.The clock of delivering to trellis encoder is provided by a speed conversion device 650, this speed conversion device goes to produce the clock signal of one 43.04 megahertz with the clock signal that the ratio of a 313*207*832/312/188/828 removes its 19.39 megahertzes of coming in of conversion.Last clock signal can reduce or frequency division removes to provide the clock of one 10.76 megahertz with a factor 4, and can supply with other parts of emission layer.In this aspect of the invention, digital unit that any one side of the buffer 208 of interleaver inputs or outputs and of the prior art comparing, be to do comparatively simply,, and do not need to consider matching problem with the pulse string mode operation in continuous pattern because these parts can operate.
Fig. 6 represents the clock of one 19.39 megahertz, and this clock can obtain from data (resemble receive in others of the present invention or revise) or from a local oscillator.The use of a local oscillator guarantees the continuous operation of trellis encoder, no matter transmit losing or transmitting loss of clock in the signal of signal.In fact, under losing (code signal), also can use this machine clock to remove to drive the Reed-Solomon encoder from the situation of the signal of transport layer.Because at least one standard-required emission layer of announcing continues to launch a signal (normally pseudo-random signal), even original encoded signal is lost, also can keep the Reed-Solomon encoder in operation, provide the data necessary signal to remove to keep a transmission signals.
In another embodiments of the invention that also have, if adopted a digital signal processor (" DSP ") that enough disposal abilities are arranged, whole Reed Suo Luomeng codings, data interlacing and lattice code and frequency translation can be finished in the DSP of a series of one or more suitable programmings, and this DSPs has been provided needed clock.
Fig. 8 represents a speed conversion device circuit, this circuit comprises one by the circuit 570 of 141 shuntings, the signal that this circuit 570 receives a clock signal (for example signal of one 19.39 megahertz) and frequency division is provided to a phase detector circuit 572, then deliver to loop filter 574, this filter drives the voltage controlled oscillator 576 of a thermal compensation.The output of TXCO576 offers a buffer and feeds back to one by the circuit 580 of 313 shuntings, and this circuit 580 also is connected with phase detectors 572.TXCO576 has a centre frequency at needed output frequency (i.e. 43.04 megahertzes), and one+/-3 hertz track, this track are arranged is the maximum frequency tolerance of carrier frequency in the DTV of standard system.
Be in operation, need only the input that a clock frequency appears at circuit, and the frequency of this signal be in the needed limit range of system, the clock of 43.04 megahertzes that produced will be allowed to input signal is followed the tracks of.If the frequency change of input signal has exceeded limit range.TXCO576 can not run out of its track yet, and will limit in desired characteristic range and keep output frequency.
Fig. 8 represents to be suitable for can represent by an external signal as the serviceability of the input signal on output signal basis, for example explanation here with the related genlocing of confidence counter circuit (SYNCLOCK) signal.When system loses synchronously, a gate circuit 582 can provide a voltage signal, and this signal will be driven into TXCO576 on the desired output frequency.In case of necessity, the amplitude of voltage signal can be provided with by the Systems Operator.For example by the adjustable potentiometer (not shown) of user.
Fig. 9, trellis encoder of 10 and 11 expressions, this encoder receives the digital data stream (DATAIN) that will encode.Digital data stream is sent to a first-in first-out (FIFO) buffer 52 and classification/timer circuit 54 and goes and the remainder of circuit aligned data in time.Be sent to a nibble (nibble) in reasonable time, data and select circuit 56, this circuit is selected two suitable nibbles according to the scheme rule of coding from the numerical data of input.In order, selected nibble is coded (for the DTV system by a trellis encoder 58, this encoder is to importing its every two bits, provide 3 dateout), supply with a multiplexer from the data of trellis encoder 58 outputs, this multiplexer utilizes sync bit and/or pseudorandom number that data are carried out multiplex operation, and the coding output of multiplexer 59 offers an output register 59.The operation of the circuit of Fig. 9 is controlled by control logic 51, the branch frame of this control logic coordination data and symbol and segment counter 53,55 are resetted when appropriate.The output of counter 53,55 offers starter 57, and this starter provides the signal of constant speed to other parts of circuit, makes each need to know the parts of the Data Position of coming in the scope of frame, and this available data are arranged.
Be in operation, a digital data stream is provided for the lattice code circuit and is transfused to buffer and the reception of classification parts.Control logic 51 checks that the data of coming go to determine the border of frame.In case set up frame, control logic 51 resets symbol counter 53 and segment counter 55 to begin a new frame.After data were received, symbol and segment counter 53,55 be by increment, and carry out their circulation according to the form of data.Symbol and segment counter 53,55 drive starter 57, and this starter is sent other parts that suitable control/selection signal is given circuit.
Fig. 9 is illustrated under the guiding of signal of self-starter 57, and the selection circuit 56 of nibble is selected suitable nibble from the input traffic that the next one will be encoded.Under the situation of the DTV of standard signal, the nibble of selection is (the annex D of television standard of numeral, the table 2) finished according to the specification requirement of DTV, though also can finish with any other conversion scheme.Therefore, each nibble is by trellis encoder 58, encodes by the order of selecting.The rules of observing according to system, as suitable appointment rules with according to the guiding of starter 57, multiplexer is alternately exported lattice code data or synchrodata.Even lose an input data signal or lose synchronously, the pseudo random streams of a data bit (" PN ") can be sent into the data flow of output by multiplexer 54.
Nibble selects circuit 56 at 12 memory register R
1, R
12Each in received digital data stream (DATA IN).The data flow of input arrives serially and can circulate and enters follow-up memory register R
1, R
12In.These 12 registers are linked a side of one first multiplexer 62.Under the control of multiplexer control signal (not illustrating) based on the location of input data in the scope at frame, this first multiplexer 62 provides one of byte of input data at its output.Second multiplexer 64 receives the byte of selecting under the control of the control signal of second multiplexer, and selects the data of two positions to go output.The position of output is sent to trellis encoder, and this encoder becomes 3 to this dibit encoding, these three next stage that are admitted to then in the emission system.
Figure 10 is that a nibble is selected circuit 56, and this circuit can be used to receive a digital data stream (DATA IN) in the present invention.A lattice code circuit can comprise an input multiplexer 72, this multiplexer is to a string 12 register R1, first of R12 loads, utilize or from the data of an input multiplexer 72, from a string 12 register R1, first of R12 loads, or is used to the load content of the last register (R12) in this string, so that cause cycling through of whole registers.In the moment of each selection, the content of last register (R12) is fed to nibble and selects circuit 74, and this circuit is selected the ladies and gentlemen two according to previously selected rules from last register R12.When each nibble is selected from last register, register of the content of all registers circulation each time makes whole 12 bytes in a section all in turn deliver to nibble and selects circuit 74, always has 4 times.When circuit 74 outputs are selected in the position of 12 whole words from nibble after, 72 couples of 12 register R1 of input multiplexer, the R12 loaded with new data goes the data of next section are encoded.
Also have the embodiment of another trellis encoder to be illustrated among Figure 11, an input traffic (DATA IN) is guided into 12 parallel register R1, R12 by one first multiplexer 82 in the figure.After in case these registers are loaded, with each memory register R1, the nibble that R12 is relevant, selection circuit 84 will be from they relevant memory register R1, and R12 selects two data bit, and the position that chooses is offered a relevant trellis encoder 86.Each trellis encoder 86 is encoded to the bit that receives, and three bits of coded is offered the input of an output multiplexer 88 according to predetermined encoding scheme.The output multiplexer is selected bits of coded according to rules from suitable trellis encoder 86.If adopted the lattice code scheme of standard DTV system, please note the trellis encoder of the embodiment among Figure 11, requiring the degree of depth is 1 and encoder among Figure 10 requires one 12 the degree of depth.
As everyone knows, the signal that often non-linear introducing is exaggerated of signal amplifier.Making can linearisation by such nonlinear amplifier amplifying signal, is to make input signal distortion in advance in one way as everyone knows, and this mode is to make distortion in advance opposite with the added effect of nonlinear of amplifier just.Figure 12 is that (amplitude of expression signal and the relation of frequency) has the input signal of form among Figure 12 (A) by a transfer function distortion in advance as shown in Figure 12 (B) (or revising in advance).After amplifier was added on the input signal of revising in advance to the enlarge-effect shown in Figure 12 (C), the amplifying signal of revising the back gained was shown in Figure 12 (D).For further instruction, in Figure 13, express as shown in figure 12 same signal and effect, but this block graphics is represented in frequency domain.
The method of revising in advance known to having been found that is subjected to the frequency response of amplifier and the restriction of system bandwidth.Being used in the correction result in advance of erase amplifier distortion, is that the input circuit that is exaggerated device is revised in phase place and amplitude.These variations in phase place and amplitude have limited the result who eliminates distortion in amplifier.For example, the input circuit of common amplifier often just like among Figure 14 shown in the amplitude and the phase characteristic of frequency range.The variation of these amplitudes and phase place has hindered the unwanted distortion of the whole amplifiers of deletion.Usually the consequential signal that obtains in such circuit is the figure of a frequency domain series as shown in Figure 15.Please note the secondary lobe of the frequency content that produces by uncorrected distortion.
A kind of to be used to delete unwanted non-linear method be between the correction in advance and nonlinear amplifier of prior art, inserts an amplitude and phase corrector.Corrector is transferred to and makes its amplitude opposite with the amplitude and the phase response of phase response and nonlinear amplifier.
Figure 16 is a circuit, and this circuit can improve the response of amplifier system, and it can comprise a nonlinear amplifier 170, with amplifier input circuit 166 and the amplifier output circuit 172 relevant with it.One is used for amplitude to the correction circuit in advance (i.e. linearity corrector) 164 of input be used for the in advance correction circuit (i.e. a phase corrector) 162 of phase place to input, can be under the mode of routine for specific amplifier 170 non-linear with the frequency range adjustment of being paid close attention to.Frequency response and phase corrector 166 are between linearity corrector 164 and the amplifier input circuit 168, and are adjusted and compensate input circuit, make that the cascade of parts is 1 to the final result of (adjuster 166 and circuit 168).Thus, corrected signal can fully be compensated in nonlinear amplifier 170 in advance.
Please note in the circuit among Figure 16 that phase corrector 162 is before linearity corrector 164.This is the preferred disposition of these adjusters, because if the order of these adjusters conversely, the adjustment that amplitude is revised in advance can produce unwanted variation in the correction in advance of phase place.These unwanted variations are to eliminate, and still, it is difficult that the adjustment circuit goes to delete unwanted interactional influence.
The amplifier output circuit 172 of nonlinear amplifier 170 usually also can change the frequency and the phase response of whole system.Control this effect, can add one with frequency response correction device 160 go to proofread and correct whole system, for the permeability of frequency and phase response.
Frequency response correction device 160 and 166 can each realize with the piecewise-linear correcting circuit, this circuit can be in a specified frequency scope frequency response and the group delay (or phase place) of corrected signal.These adjusters must be able to be accomplished: (1) revises the characteristic of amplitude to frequency, and irrelevant with phase place (delay); (2) revise the characteristic (so-called " group delay ") of phase place (delay) to frequency.In a preferred embodiment, the frequency response correction device will be realized each performance of these regulations independently.
Be used for this group adjuster of this aspect of the present invention, can be designed as from phase corrector 162 and linearity corrector 166.Such Correction circuit generally can be designed to produce the required pre-distorted signals with the unusual anti-coupling of amplifier.Designed linearity and phase corrector, followed frequency response correction device to design subsequently, because it will proofread and correct the error relevant with frequency that is caused by amplifier input circuit in the linearity corrector back.At last, can be designed to eliminate error in the total transfer function that comprises the amplifier output circuit at the frequency response correction device of signal flow the beginning part.
Figure 17 represents that the parts identical with Figure 16 indicate with identical reference number, can know in prior art systems, revises in advance normally to finish at an intermediate frequency.The calcspar of this aspect of the present invention can make into as shown in Figure 17, and wherein frequency mixer (or converter) 174 is placed in advance between the correcting part and nonlinear amplifier 170.Can offer frequency mixer 174 with signal, go signal transformation to one a new frequency that is exaggerated from a frequency reference 176.Frequency reference 176 can comprise an oscillator, and tuning circuit, the device of outside reference or any routine or circuit go to supply with a reference frequency.
Accurate FREQUENCY CONTROL requirement, this requirement proposes the DTV broadcasting station, to guarantee and the lowest interference of other channel, just requires intermodulation product, and frequency stability and control give special concern.One is used to obtain a system of satisfied FREQUENCY CONTROL as shown in the functional block diagram of Figure 18 and 19, the figure shows a typical place, produced TV signal (for example studio) (Figure 18) in this place, and be broadcasted (for example transmitter scene) (Figure 19) in this place TV signal.Figure 18 represents that the studio audio/video can be supplied with the MPEG-2 encoder 180 of a routine from multichannel and the TV signal alternating signals source, and this encoder utilizes the clock reference 182 of an outside in a kind of mode of routine signal to be encoded.Clock reference 182 can be the clock source of any high stable, particularly the clock source being convenient to receive, place, for example gps signal of a global positioning system in the distance.Encoder 180 can provide the decoder of an inside, so that a monitor signal is provided for the audio frequency-televimonitor 184 of this machine.Coded television signal is supplied with the conveyer 186 of system of a great alliance (GRAND ALLIANCE), and this device will turn to the MPEG-2 signal format of coming in " transfer layer " needed suitable form of great alliance system.In other words, the conveyer of great alliance (GA) can (by a selectable switch) receives a signal from the MPEG-2 signal generator of an outside.The formative signal of transport layer can offer multiplexer 188, and this multiplexer carries out multiplexed to the signal of transformatization and other data and provides multiplexed data to transmitter 190, is used to be transmitted into a broadcast transmitter scene.Along some parallel path, " TV of standard " vision signal or signal can be transformed to the form of numeral by the converter to numeral of a simulation, and digitized vision signal can offer the compressor reducer 194 of a NTSC4/1 with its corresponding digital audio signal.Compressed digital NTSC signal is provided for multiplexer 1888, is used for carrying out multiplexed with the formatted signal of transfer layer and being used for launching by transmitter 190.Each encoder 180, transport layer device 186, multiplexer 188, A/D192 and compressor reducer 194 are to be locked on the common clock benchmark 186.If clock reference is to obtain from well-known global positioning satellite system (or any identical existing systems stabilisation), the 1 megahertz reference signal that is provided by satellite system can be provided in the studio.(produced) DTV signal and digital NTSC signal like this by transport layer device 186 all locked, is used for the effectively scene that is transferred to transmitter of numeral.Because the DTV signal is locked into public reference clock, multiplex operation can be finished with the NTSC signal of numeral in a synchronous mode.
Figure 19 represents that when multiplex signal arrives the transmitter scene it can be carried out multichannel decomposition (the forward error correction signal that this demultiplexer can use transmitter 190 to provide) by demultiplexer and be provided out as DTV and two data flow of NTSC.The DTV signal can the formatted broadcasting that is used for DTV, and amplified by an exciter 200, power amplification and upconvert, and broadcast away by one pair of suitable antenna 204 at last.The NTSC signal can be decoded to base band and pass through conventional devices broadcasting by a ntsc decoder 208.Demultiplexer 198, exciter 200, each all is locked into a common clock benchmark 212 power amplifier and up-converter 202 and ntsc decoder 208.
Also can public other stable clock reference signal go to realize advantages more of the present invention at scene, studio and transmitter scene.For example, if transmitting near the STL between transmitter scene, studio and transmitter very much, the scene, studio just can eliminate, and clock signal can transmit between studio and transmitter with the method for routine.
If needs are arranged, this is illustrated in the less several of whole parts relevant with clock reference (CLK REF) among Figure 18 and Figure 19, need link independent (or relevant) clock reference.If DTV exciter 200 and transmitter (power amplifier and upconvert 202) only use a public clock reference, resulting adjacent the disturbing with co-channel (adjective) of this embodiment of the application of the invention just can improve.In addition, by use a public clock reference in many places, advantage of the present invention can be used to many occasions more widely.If many exciters and transmitter use a public stable benchmark, satellite-signal for example, each satellite-signal can produce a NTSC and DTV signal, this signal can not only reduce the interference with produced simultaneously TV signal, can also reduce with the interference of other signal that produces in other occasion, the appointed channel of other occasion because the inaccuracy of frequency may cause interference in addition.
An emission system that is used to launch a radiofrequency signal comprises: be used to receive a device that contains the data-signal of the voice data of having encoded and video data, wherein, described signal comprises one first clock signal; Be used for restoring the data-restoring device of this first clock signal from this data-signal; A data data randomizer in proper order that is used for changing this data-signal; An encoder is encoded to this randomized data-signal according to the specified coding scheme; A lattice shape (trellis) encoder, be used for to this encoded data signals carry out lattice shape (trellis) coding; A pulse shaping device constrains in this lattice shape (trellis) encoded data signals within the fixing bandwidth; Be used for a pilot signal is joined the pilot signal device that this bound data-signal goes; Upconvert device with this a bound data-signal and pilot signal upconvert to a channel frequency; Be used to amplify this data-signal of upconvert and amplifier installation of pilot signal; And the broadcaster that is used to launch this all signal that amplified.
Claims (14)
1. emission system that is used to launch a radiofrequency signal comprises:
(a) be used to receive a device that contains the data-signal of the voice data of having encoded and video data, wherein said signal comprises one first clock signal;
(b) be used for from the data-restoring device of this this first clock signal of data-signal recovery;
(c) data randomizer is used for changing the order of these data-signal data;
(d) encoder is encoded to this randomized data-signal according to a kind of specified coding scheme;
(e) a lattice shape (trellis) encoder, to this encoded data signals carry out lattice shape (trellis) coding;
(f) pulse shaping device is used for constraining within the fixing bandwidth carrying out lattice shape (trellis) encoded data signals;
(g) pilot signal device is used for a pilot signal is joined this bound data-signal;
(h) be used for upconvert device with this a bound data-signal and pilot signal upconvert to a channel frequency;
(i) be used to amplify the amplifier installation of this bound data-signal and pilot signal; And
(j) be used to launch the broadcaster of all signals that amplified.
2. the described emission system of claim 1 comprises the device that the frequency error in described first clock signal is measured, and the device that the frequency of this upconvert signal is adjusted according to a numerical value relevant with the error of being measured is adjusted, made to described upconvert device.
3. in the described emission system of claim 1, described encoder is a Reed-Solomon (Reed Solomon) encoder, and described pulse shaping device is a nyquist filter, and wherein said nyquist filter be one from root-liter-cosine filter, it has one and is about 0.115 the α factor, and described nyquist filter is a finite impulse response filter preferably.
4. in claim 1 to 3 in any one described emission system, after this data-signal is by shaping pulse, this pilot signal is inserted in this data-signal and goes, and this data-signal was converted into an analog signal before by upconvert.
5. in the described emission system of claim 4, described upconvert device comprises an intermediate frequency mixer and a channel mixer, described intermediate frequency mixer receives a resting frequence signal of having derived from described first clock signal, and the frequency of described resting frequence signal is adjusted according to the error of described first clock signal.
6. in the described emission system of claim 5, described channel mixer receives a second clock signal of having derived from described first clock signal, and described second clock signal is adjusted according to the error in described first clock signal.
7. in a television emission system, use a kind of Reed-Solomon coding and a kind of lattice shape (trellis) coding method that the set of number TV signal is encoded, before being sent to broadcaster, a pilot signal is inserted in this TV signal of having encoded goes, before inserting described pilot signal, this TV signal of having encoded is by shaping pulse.
8. a digital TV transmitter comprises a digital modulator, be used to receive and comprise that preparation imports all signals by a data part and the clock numeral partly of all signals of TV information of this transmitter emission, this digital modulator comprises a number format circuit, be used for formaing to importing all signals by the numeral of this transmitter emission, a D/A conversion circuit, be used to provide as all signals of the digital dock of an output, a power amplifier circuit, be used to receive all signals of this simulation output, should simulate all signals of output and carry out mixing with at least one CF signal, and amplify CF signal after this mixing, this power amplifier circuit comprises at least one up-converter level, be used to receive a CF signal that contains a reference signal, a clock correction circuit receives this digital dock input signal from this digital modulator, so that detect any deviation in this digital dock reference signal, and provide a deviation signal, function as detected departure degree, also has a variable CF signal source, be used to produce this CF signal and this reference signal, in response to all deviation signals, so that change the carrier frequency frequency along the direction of any deviation that compensates this digital dock input signal from this clock correction circuit.
9. in the described transmitter of claim 8, this power amplifier circuit comprises two up-converter frequency levels, one first medium frequency converter and one second output radio frequency carrier frequency frequency converter, a resting frequence source and an output frequency carrier frequency source, be used for providing all carrier frequency frequencies to this intermediate frequency and all frequency converters of output radio frequency respectively, this intermediate frequency source provides this reference signal, and in response to this deviation signal from this clock correction circuit, revise all signals of this simulation carrier frequency, so that compensate any deviation of this digital dock input signal, wherein any deviation of input clock input signal all reflects in the reference signal that this analog output signal comprised, simultaneously, change the frequency of this reference signal from the mode of this reference signal of at least one up-converter output with a kind of correction from this deviation signal of this correcting circuit.
10. a digital TV transmitter comprises a divider chain, be suitable for receiving set of number data flow corresponding to all signals of Digital Television, so that according to this digital data stream of all standard format of Digital Television and should be converted to analog form by formative digital data stream, a power amplifier, be connected with analog form and from this divider chain that contains at least one mixer, receive all signals of this Digital Television, so that modulate all signals of this Digital Television with analog form with a carrier frequency that is in an appointed television channel frequency, and amplification has all CF signal of the bandwidth that meets all standards of Digital Television, simultaneously, a pilot tone is inserted circuit and is connected to this divider chain, so that before this digital data conversion is analog form, a pilot signal is inserted in this digital data stream goes, wherein, this digital data stream that is received by this divider chain comprises a clock signal, and this divider chain extracts this clock signal from this digital data stream, described transmitter also comprises a frequency control circuit simultaneously, be used to control and be connected the frequency of bandwidth that applies this modulated all CF signal of all upconvert signals to one of all mixers, this frequency control circuit is connected, so that receive all clock signals that this has extracted from this divider chain, and this all clock signal that extracted compared with a standard, and use this difference to go to control the frequency of all upconvert signals.
11. in the described digital TV transmitter of claim 10, this divider chain comprises the first and the second portion under a rate transition circuit control that are synchronized with all signals of input digital data, this rate transition circuit is synchronized with all clock signals of all digital data signals, but if all digital signals depart from default all limit values, then provide with all digital signals irrelevant synchronously.
12. a digital TV transmitter comprises a digital modulator, be used to receive all digital input signals, the latter comprises the TV information all signal of preparation by this transmitter emission, this digital modulator comprises a number format circuit, being used for that numeral is imported all signals formats, so that launch by this transmitter, a D/A conversion circuit is used for this formatted all digital signal is converted to all signals of simulation output, and circuit, be used to provide this digital dock to import all signals as an output, a power amplifier circuit, be used to receive all signals of this simulation output, should simulate all signals of output and carry out mixing with at least one CF signal, amplify the CF signal after this mixing, this power amplifier circuit comprises that at least one upconvert level is used to receive a CF signal that comprises a reference signal, a clock correction circuit receives this digital dock input signal from this digital modulator, so that detect any deviation of this digital dock reference signal, and provide a deviation signal, function as detected departure degree, also has a variable CF signal source, be used to produce this CF signal and this reference signal, in response to all deviation signals from this clock correction circuit, so that the direction along any deviation that compensates this digital dock output signal changes the carrier frequency frequency, wherein this power amplifier circuit preferably comprises two upconvert frequency levels respectively, one first medium frequency converter and one second output frequency carrier frequency become tired device, resting frequence source and all frequency converters of output radio frequency, and this intermediate frequency source provides this reference signal, simultaneously in response to this deviation signal from this clock correction circuit, revise all signals of this simulation carrier frequency, so that compensate any deviation in this digital dock input signal.
13. one kind by a television transmitter, to prepare within the scope that frequency by all signals of Digital Television of a digital TV transmitter emission remains on all standards of Digital Television to reduce the method that potential cochannel disturbs, this television transmitter is suitable for receiving all TV signal from a TV signal source, this TV signal source is with the form of digital data stream, follow this digital data stream synchronously in related all clock signals together, and be used to launch digital data stream as all signals of Digital Television, comprise and from this data flow, extract all clock signals, this all clock signal that extracted is compared with a reference clock signal source, to produce a difference signal, the latter is all clock signals of having extracted function with the sequential between all reference clock signals, and use this difference signal, the all clock signals that extracted with a kind of compensation go to control the tranmitting frequency of this digital TV transmitter with the mode of any deviation on the sequential between all reference clock signals, wherein this digital transmitter comprises a power-amplifier stage, it has at least one upconvert level, so that go to modulate a higher frequency with all signals of armed Digital Television, and use this difference signal to go to control the step of this tranmitting frequency, the all clock signals that extracted along a kind of compensation are with the direction of any deviation on the sequential between all reference clock signals, and control puts on the higher frequency of this upconvert level.
14. in the described method of claim 13, this power-amplifier stage comprises an intermediate frequency up-converter level and a channel frequency frequency converter level, use this difference signal to go to control the step of this up-converter level frequency, use this difference signal, the all clock signals that extracted along a compensation are with the direction of any deviation on the sequential between all reference clock signals, go to control the IF-FRE that puts on this intermediate frequency up-converter level, this digital TV transmitter is converted to analog signal form with this digital data stream, the latter is representing armed all digital signals, and this analog signal comprises a reference signal, in this comparison step, this clock signal that has extracted is with any deviation between this reference clock signal, all in this reference signal that this analog signal comprised, reflect, and, the step of using this difference to go to control this tranmitting frequency goes to control this higher frequency that puts on this up-converter level along a correction from the direction of this reference signal of at least one up-converter level output, so that change this higher frequency.
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|---|---|---|---|
| CN 98106313 CN1204897A (en) | 1997-04-04 | 1998-04-03 | Transmitting system and method |
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| US042,932 | 1997-04-04 | ||
| CN 98106313 CN1204897A (en) | 1997-04-04 | 1998-04-03 | Transmitting system and method |
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| CN108762154A (en) * | 2018-06-05 | 2018-11-06 | 中国电子科技集团公司第四十研究所 | The parallel down coversion FPGA data processing system of Vector Signal Analysis high speed and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108762154A (en) * | 2018-06-05 | 2018-11-06 | 中国电子科技集团公司第四十研究所 | The parallel down coversion FPGA data processing system of Vector Signal Analysis high speed and method |
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