CN85101659B - Transmission system for tv - Google Patents

Abstract

In a multi-channel television transmitter whose signals are in a time-division form, a video component is obtained from a video source and coded in an MAC encoder. Coded signals are modulated in a frequency modulator which also receives oscillation signals from an oscillator, and the output signals of the frequency modulator are added to the transmitter through a multiplexer and then are transferred to an antenna by a carrier of the transmitter for transmission to a satellite. The apparatus comprises sound / data information sources which are divided into a group A and a group B and are added on two multiplexers, wherein the output ends of the multiplexers are respectively arranged at the input end of another multiplexer. The line synchronization character data of a synchronization generator and data from the information sources are transferred to a data compilation device and are converted into a multi-channel signal data pulse series in a time-division form in the data compilation device.

Description

Television transmission system

The present invention relates to the television transmission system of time-division multiplex signal, in this system, row in the information frame is made up of digital data pulse string and video signal components, data in the pulse train are from the information source of multicomponent signal, they are made time-division multiplex with the form of information sets and handle, and the speed of the data in pulse train is Mbit/s.The present invention also relates on limited frequency band to use native system and equipment that system adopted.

Such data transmission system has advised using with the satellite video signal, and sound and other data (except that main video) all transmit with digital form here.

March nineteen eighty-two made Britain will nineteen eighty-two TV programme via satellite directly after the decision of broadcasting (DBS), be the report that chairman's advisory group embarks relevant transmission technical standard by Authony.Part.The result of study of this group, promptly Cmnd8751 " direct broadcasting-consulting group via satellite is about the report of transmission technical standard " as recommendation, with Her Majesty's document office name, announces in November nineteen eighty-two.The multi-channel analog components of system as directed (C-MAC) of (Britain) Independent Broadcasting Authority has formally been passed through DBS, and has formally adopted it afterwards.

The C-MAC system has illustrated in the experiment in Independent Broadcasting Authority August nineteen eighty-two and development report 118/82 " television system of MAC-high-quality satellite broadcasting ", A-MAC system (prefix relates to the type of sound and other transfer of data) has also been introduced in this report, the performance index of these two systems have been provided in the report suggestiveness, because this system has adopted DBS, will do some correction to the C-MAC system, video waveform variation structurally includes the reducing and the lengthening of sound/data component of result of change-over period of sound/data, colourity and luminance component.

Accompanying drawing 1 has provided the cycle of C-MAC TV signal delegation, and every row occupies 64 μ s, and every row is divided into many bits or sampling period with the clock rate of 20.25MHz, and every row is about 1296 sampled points.Fig. 1 is that the 11st page of Fig. 1 fetches from European broadcasting organization (EBU) the report supB284 in June nineteen eighty-three " 12GHz satellite broadcasting 625 a row television standards " literary composition, this paper it as a reference, and also incorporated its content, the included content of every row order is as follows:

The a=203 bit, synchronously, sound/data (data burst)

B=4 sampled point-ED conversion

C=15 sampled point-main clamp cycle (zero level of chromatic component)

SC1=6 sampled point-video signal coding is reserved the backup sampling point

D=354 sampled point-carrier chrominance signal (C)

G=704 sampled point-luminance signal (Y)

SC2=6 sampled point-video signal coding is reserved the backup sampling point

H=4 sampled point-enter data transaction

Chroma signal component compression ratio in time is 3: 1, the chrominance information that makes about 52 μ s is compressed together in company with the colored color difference signal of B-Y of colored color difference signal of the R-Y that transmits on the alternate row and interlacing transmission and only accounts for 17.48 a μ s(354 sampled point), luminance signal compression ratio in time is 3: 2, so being compressed, the monochrome information of about 52 μ s occupies 34.76 μ s(710 sampled points), for the DBS transmission, compressed colourity and luminance component carry out frequency modulation(FM) with the bandwidth of 27MHz, and the radio frequency carrier wave utilizes digital audio/data component to do two-phase or quarternary phase-shift keying (QPSK) modulation, present suggestion is, sound/data component should be the packet group demultiplexing, it is on 624 row of each television frame, each packet group contains 751 bits, there are 195 available bits totally 624 to go (in preceding 8 bits of each data pulse string on each row, the data flow that comprises 1 bit begins the capable synchronization character with back 7 bits), this can find out in Fig. 2, Fig. 2 fetches from Fig. 2 of EBU report above-mentioned, a packet group is occupied the cycle data of about 195 bits 3.85 in each television line, and whole the 625th row, as introducing in the EBU report, it is loaded with data entirely.In Fig. 2:

S-is the row synchronization character

L1-L625-data pulse string every trade number

The scope that the V-vision signal is shared

The P1-P162-packet group

The data of L625D-in 625 row

Each family utilizes the suitably parabolic antenna and the low-converter of size sensing satellite, can realize directly receiving the transmission of DBS, and the effect of low-converter is that incoming frequency is transformed to the U.H.F frequency band.Advise that also some families receive the signal that comes through the cable TV transmission system, this system can transmit other TV programme at one time, and unnecessary independent antenna is arranged.The place very weak for satellite-signal, cable transmission mode obviously are the superiority that it is arranged.For example, these places are originally not plan to want now to that area transmission the place that receives: requiring has complicated antenna array, from being positioned at the place of the several satellite received signals on the different resting positions, perhaps being difficult to point to the satellite eminence at antenna has the place of blocking.

The report chapter 7 of Part has been spoken of the correlation between DBS and the cable communication system.And also reported the suggestion of Britain cable TV association, even C-MAC is chosen to be the DBS transmission standard, they also still have the ability to provide cable service.Provided several examples in that chapter, adapted with C-MAC, the sort signal form can directly transmission on cable system.What present cable communication system adopted is coaxial cable, on the U.H.F frequency band, transmits their TV programme.But, some arguements are also arranged at present, the system that whether will install in the future should equally with many systems adopt optical cable, still still uses coaxial cable on the viewpoint of low construction cost.

People recognize and transmit the C-MAC signal and convenience unlike original imagination on the VHF cable communication system recently, because the 27MHz frequency band of this signal will occupy very big bandwidth, thereby reduced cable system and can be with the number of programs of carrying, and especially on the Continental Europe, it conflicts mutually with the channel spacing that expansion only accounts for the cable channel of 7MHz bandwidth at present.Owing to can produce short time delay reflection in the system, and the bit rate of such cable system is very low, therefore uses to transmit sound/data-signal up to the speed of 20.25M bit/s and will produce serious problem in cable system.Consider these top suggestions, controlling these signals, to make it be before signal is delivered to cable system in the practical methods of VHF cable system transmission, just C-MAC signal transformation is become PAL type signal, such conversion will be lost the advantage of time-division multiplex colourity and brightness, pay in the carrier system in colourity, again produce the shortcoming of intersection-colourity and intersection-brightness, but importantly in order to prevent unofficial reception, in fact received DBS signal is encoded.The TV service that unofficial reception is for example charged, it is decoding earlier before conversion, then the signal after the conversion is encoded again.

Also do not criticize patent № 8306921(PHB32963 down at us to Britain application) in, we advised be overcome the problems referred to above can be with the method for vision signal being made amplitude modulation(PAM) (being compressed chromaticity and luminance signal) with the method for data pulse string broadening (digital audio/data division).Can reduce bit rate like this, it can be transferred on single carrier wave.This suggestion has reduced desired bandwidth significantly, but it still needs the bandwidth of 14MHz, is actually the bandwidth of two channels, wishes that the DBS signal only is included in a cable staff's in the channel approval so this can not cause.

People appreciated afterwards be if adopt amplitude modulation bandwidth constraints in the desirable 7MHz band of European cable worker, after on display, expanding, the image that the colour that does not have intersection that the shown television image of the video component of MAC system comes from the PAL television signal transmission system, the PAL signal that intersects brightness defect are produced is equally good, if but they are modulated with carrier wave independently respectively owing to the reason of frequency band, data pulse string at the MAC signal still keeps time-division multiplex in the time, still can leave the problem of sound/data.A suggestion by the proposition of portion of Deutsche Post to cable operated, be when still keeping four phase signals on the bit rate of 20.25M bit/s, all sound/data component is done modulation again, 20.25M the signal of bit/s can be made up of the symbol of 10.125MHz speed effectively, each symbol is in four level and the information that has two bits.Yet this suggestion has found that the reflection on the cable is very sensitive, and the recovery of Zhong Pin is also very difficult, and signal has only very little level and vertical eye pattern.Another suggestion is that bit rate is reduced by half is 10.125M bit/s, when adopting doubinary encoding (three level signal, interference is deliberately arranged between the symbol) time, just can on cable, transmit, the bandwidth that it requires is 5.0625MHz, this compares with the C-MAC packet group system that top EBU the report recommends, it only can transmit half of sound/data component.The advantage of said system and problem are at the report MDD/RDT/007/84/MA of CCETT.Done discussion in " Le Codage MAC/Duobinaire-Adaptation du Signal C-MAC-Paquets aux Reseaux Terrestres ", article is write on January 19th, 1984 by M.Alard and R.Lassalle.

Reducing a large amount of information component, to make the shortcoming of transmission on the speed 10.125M bit/s that it can reduce be that the cable staff must select him to require four information sources that are used for transmitting on cable when receiving the C-MAC signal, according to the suggestion in the EBU data, the practical method that forms the packet group signal from different information sources will be the sound/data source shunt the C-MAC signal, with these signal storage along separate routes, select the information source with vision signal of four requirements, synthetic these selected source signals of multichannel (8 sound/data sources suggestions are with the speed of 20.25M bit/s in the C-MAC grouping, and four sources are the speed of half) again before being sent to cable then.

The purpose of this invention is to provide a transmission system, and this system can avoid above-mentioned pointed shortcoming just.

The invention provides a television transmission system, the main signal form of row is a time-division multiplex in per frame period, and it includes digital data pulse string component and video signal components.Data in the data pulse string component are from various information source, from each information source, they are all formed the pulse group by time-division multiplex, the bit-rate of data pulse string is M bit/s, comprise a plurality of predetermined data bits in the data pulse string, it is characterized in that and to be divided into the N group to described signal source, concerning every group, data from information source are by time-division multiplex, and a series of bit pulse group of coming from each source forms N son-multiple signals with the form of data bit flow.Data bit has been formed corresponding each row of data pulse string, data pulse string bit-by-bit ground, continuously from N data bit stream, obtain and constantly the transmission, its bit-rate is above-mentioned M bit/s, effective data rate in the data of each information source group of data pulse string is M/N bit/s, and the bit quantity in the data pulse string should be the integral multiple of the number N of information source grouping.

Said system allows easily to obtain from data pulse string from the data that different information source groups are come, so in actual applications, in order to improve the transmission of TV signal on limited broadband, can be from a certain group of data of coming with the single use of TV signal that has improved.

Information source can be divided into two groups, and the consecutive line of each data pulse string always since first bit of two groups together.

The present invention also provides the transmission of television that is used for above-mentioned television transmission system machine equipment, this system includes the information source of vision signal, it produces the vision signal of time-division multiplex, many sound/data-signal information source, handlebar sound/data-signal is made the device that time-division multiplex is handled by Digital Signal Processing with digital signal as the form of series of pulses group, the time-division multiplex signal is in the data pulse string component of TV signal, its bit-rate is M bit/s, and described data pulse string component comprises a plurality of predetermined data bits.It is characterized in that the information source of sound/data-signal is divided into the N group, the signal that the handlebar time-division multiplexization is come from the information source of each information source group constitutes a string bit pulse group with the form of bit stream, thereafter the device of recomposition N son-multiple signals, by from each of N bit stream, taking out bit and bit signal being formed the device of data pulse string, make the relevant row of data pulse string contain the bit that speed one by one from each of N bit stream is the M bit/s that proposes previously continuously.And the effective data rate that requires the data of each group in the data pulse string is M/N bit/s.The sum of the bit in data pulse string is the integral multiple of packet count N.

When the information source of sound/data-signal is divided into two groups, a choice device of choosing bit from each group is arranged, make consecutive line first bit in two groups of each data pulse string begin.

The present invention also further provides the TV receiving apparatus that is used for above-mentioned television transmission system, and it includes the device that TV signal receives, the device of separating video component from TV signal, the device of generation data pulse string signal from TV signal.It is characterised in that receiving equipment has additionally comprised the device of choosing bit from the data pulse string of representing a specific information source group.

This equipment additionally includes again vision signal is modulated to the device that carrier wave gets on, its bandwidth is less than the bandwidth of the signal that is received, this device can be further used for the bit in some information source groups form data rate be M/N bit/s improvement data pulse string, this data pulse string that has improved comprises and equals original a plurality of a plurality of data bits divided by group number N, also provided the device that data pulse string is modulated to the time-division multiplex TV signal of the data pulse string that makes it constitute another video component that comprises limited bandwidth on the carrier wave and improved.

Above-mentioned some characteristics with other of the present invention will illustrate that with reference to the accompanying drawings, they are with embodiment:

Fig. 3 is transmitter square figure used in this invention.

Fig. 4,5,6, the 7th is used for the clock figure of key diagram 3 transmitter apparatus work.

Fig. 8 is the calcspar of receiver used in this invention and frequency converter.

Fig. 9 is the comparison detailed block diagram of certain part among Fig. 8.

Figure 10 is the clock figure of key diagram 9 part operation principles.

Calcspar according to Fig. 3 of the present invention, it is transmitter apparatus, it is used for producing a kind of time-division multiplex TV signal form, the video component of transmission equipment is provided by video signal source 1, and it is added on the MAC video encoder 2, be compressed and make up under the ratio that they require from the brightness and the colored color difference signal of information source 1, as shown in Figure 1 in the time mode.Suppose not do to encode from the MAC video component of encoder 2, if but it still to encode, encode in encoder 2 with any known technology so.This technology is the commentary that just obtains significant recently.Be added on the frequency modulator 3 from the multi-channel video component of encoder 2, also be added to above it from the oscillator signal of the appropriate frequency of oscillator 4, the bandwidth that the signal that is transmitted is like this occupied on the tranmitting frequency that requires is 27MHz.The modulated output that obtains from modulator 3 is added on the Port Multiplier 5, and its output is delivered on the parabolic antenna 7 by transmitter 6, directly transmits to corresponding satellite.Video signal generating equipment, its structure and work say that relatively everybody knows quite well, and are not further introduced here.

Transmitter, it comprises 8 sound/data source, numbering from 8 to 15, also can number conversely, include a pair of information source that the stereophonic signal that combines with vision signal is provided, also have some that other stereo or single-audio signals are provided in addition, and the data of teletype signal form and be used for the data of monitored space and the information source of other signals.In present introduction, suppose that information source 8 and 9 provides two voice signals conducts and video signal mixture stereophonic signal together, information source 10 signal of offeing telex, it can be used for mixing captions for vision signal, information source 11 then provides top mentioned air surveillance signal, these four information sources are formed first group " A ", among the information source 8-15 each all has input terminal C, it can receive from the corresponding clock signal of clock generator 16 outputs, and the frequency of clock signal and the characteristic of information source adapt.Be added to respectively from the output of information source 8-11 in the input or first packet group Port Multiplier 17 of " A ".Their form second group " B " output of remaining information source 12-15, are added on the input or second packet group Port Multiplier 18 of " B ".In order to receive from the speed of gate generator 16 outputs is the clock pulse of 10.125MHz, and packet group Port Multiplier 17 and 18 all is added with clock input signal C1." A " group Port Multiplier 17 obtains supplied with digital signal from information source 8-11, and the synthetic packet group that has the suitably preceding top guide of form known of these sets of signals, its speed is 10.125M bit/s, in the C-MAC packet signal of recommending in the shared time range of the combination of these packet group and the top EBU report that data pulse string occupied was similar.Fig. 4 is included in time relationship from son-multiple signals that the output of " A " packet group Port Multiplier 17 obtains with diagram explanation.When bit rate is 10.125M bit/s, it has 98 bits in each row, if each packet group has 751 bits, each packet group will be occupied 7.66 of about delegation so, some conforms to Fig. 2 among Fig. 4, Fig. 4 has provided the bit on top, each bit in being expert at is represented with A, the numbering number of the numeral bit of its suffix, be expert on the L1, initial (it finishes during the L8 that is expert at) of grouping represented with two-wire, each frame neutron-multiple signals " A " includes 81 such packet group, and 321 vacant bits are arranged in addition, and it finishes at 621 row is starting, and by row 622,623 and 624 expansions are so the number of bit rate in each son-multiple signals and packet group is half of number of defined in the above EBU report.The signal that comes from information source 12-15 uses the same method by 18 processing of " B " packet group Port Multiplier, bit number in every row also is 98, per 751 bit groupings groups also approximately occupy 7.66 row, in this case, in every frame, son-multiple signals, " B " also contains 81 packet group, the vacant bit that similar number is arranged, as son-multiple signals " A ", the row of appearance number is 621,622,623 and 624.The graphic extension of son-multiple signals " B ", it should come reference numbers with identical method among Fig. 4 in Fig. 5.

" A " and " B " son-multichannel composite signal that obtains from " A " and " B " packet group multiplexer 17 and 18 is added to the input of Port Multiplier 19 respectively.In order to receive from the clock pulse of the 20.25MHz of gate generator 16, also be added with input clock signal C2 on the Port Multiplier 19, multiplexer 19 alternately transmit bit rate be 20.25MHz from " A ", " B " packet group multiplexer 17 and 18 " A " and " B " son-multichannel composite signal, that the multiple signals that make such formation alternately extract from sound/data source 8-15 two groups (A and B) and speed is arranged is 20.25M bit/s.Be added in first input of Data Assembler 20 from the output of Port Multiplier 19, it also can be the form of multiplexer.Its second input is connected with the output of synchronization character generator 21, also be added with clock input C3 on the synchronization character generator, it receives from the output clock pulse of the 20.25MHz of pulse generator 16, synchronization character generator 21 produces 8 bits, just the capable synchronization character of initial sum 7 bits of 1 bit is formed, in assembled frame data, it is to be added in the capable front of each sound/data bit.

The 3rd input of Data Assembler 20 is connected with information source 23, it is to be used to make data to occur on 625 row, as introduce in the top EMU report (if do some modification by following method, can be 624 row), in order to receive from the clock pulse of the 20.25MHz of gate generator 16, clock input C4 is arranged on the information source 23, the output packet of Data Assembler 20 contains the Frame of the row 1 of C-MAC packet signal to row 625, some difference of suggestion during it and top EBU report, in this suggestion, each bit of valid data is alternately to obtain from two groups of information sources, the valid data of every row partly are 196 rather than former 195 bits of suggestion, but the data message of row synchronization character and row 625 is former forms, its output is the data input as the 2-4PSK modulator, in order to produce phase shift keyed signal, another input is a connection oscillator 4, receive oscillator signal, phase shift keyed signal is added on the Port Multiplier 5, makes this modulating data can insert in suitable time slot in the C-MAC packet group signal and goes.

Fig. 6 has provided the compilation form of data bit in the Frame, and sound/data bit always begins with information source group A on each row, and B finishes with information source, makes to include 98 " A " bits and 98 " B " bits in every row.

Along with valid data cycle of every row is increased to 196 bits from 195, if the cycle of every row is still contained 1296 sampling periods, so the number of the bit of the remainder of Hanging or sampling need change.So suggestion will reduce a bit a little, and the transient period increases a bit slightly for the number in video signal components sampling period.The form relevant with figure will be done some following modification:

A=204bit, synchronously, sound/data (data pulse string)

The b=5 sampled point, the ED conversion

The c=15 sampled point, the main clamp cycle (zero level of chromatic component)

The SC1=5 sampled point, video coding is reserved backup

The d=352 sampled point, colourity (C)

The g=704 sampled point, brightness (Y)

The SC2=6 sampled point, video coding is reserved backup

The h=5 sampled point enters data transaction

By noted earlier, whole the 625th provisional capital is loaded with data, and Fig. 7 a has provided the structure of row, wherein:

FSD=104bit, the frame synchronization data

UDT=5bit, unified data and time standard

SDF=94bit, fixing Frame

RDF=470bit, the Frame of repetition, it contains the data pulse group TDMCTL(1 of 5 94 bits)-(5)-time-division multiplex control group.

NA=564bit, the data pulse group of 6 94 bits, not appointed.

UDF=59bit, undefined

Frame synchronization data (FSD) contain:

LSW=8bit, the 1 bit demodulation device work of entering adds 7 bit-rows synchronization characters

CRI=32bit, clock enters work.

The FSW=64bit frame alignment word

For desired data in the 625th row are received in the frequency mixer of cable front end with 1/2 bit rate in line period, another suggestion is to do some modification to row 624,625, shown in Fig. 7 b.According to present system, to transmit static Frame (SDF) in the cycle of suggestion row 624, and in this cycle data, stay 102 bits and do not do definition (UDF1), its valid data cycle is not obtained sound/digital signal from the 8-15 information source.The 625th capable being revised as is not with static data frame signal (SDF), but continues to be loaded with other information.End at the 625th row is increased to 153 bits to the undefined cycle (UDF2), and the reason of this variation will illustrate below.

Fig. 8 is the calcspar of receiver, and it has a frequency mixer, and it can be transformed into the C-MAC TV signal of introducing above that receives and be suitable for the TV signal that cable communication system adopts.Provided parabolic antenna 31 among the figure, in order to receive C-MAC packet group DBS TV signal, it should have suitable size dimension, and the DBS TV signal specifies in the broadcast band of 12GHz.What join with antenna 31 is down-conversion mixer 32, and the frequency of input signal is shifted in the UHF broadcast band in frequency mixer, greatly between 950-1750MHz.They can easily be delivered on the input terminal 34 of receiver through coaxial cable 33 like this.In receiver, the signal of terminal 34 is delivered to tuned cell 35, and here it is mixed mutually to produce intermediate-freuqncy signal (i.f.) with tuning local oscillation signal, and this moment, its intermediate frequency was 134MHz.Adopt this usual way just can select the TV signal that requires.The bandwidth of the intermediate-freuqncy signal of tuner and generation is 27MHz, and just in time the bandwidth with DBS is consistent for it.Tuned cell 35 adopts selects voltage method to finish tuning work, this voltage be added to link to each other with selector (not drawing) unit 36 on, it is again as first input of adder circuit 37.The output of add circuit is connected on the corresponding input of tuner 35.Add circuit 37 also has second input, is added with automatic frequency control (a.f.c.) voltage of sending here through line 38 on this.AFC voltage is added on the selection control voltage, to guarantee the correctly tuning of tuned cell 35.Be exaggerated at amplifying stage 39 from the intermediate-freuqncy signal of tuned cell 35, be added to then on surface acoustic wave (S.A.W.) filter 40, the centre frequency of this filter is 134MHz, and passband is 27MHz.The output of Surface Acoustic Wave Filter 40 is to be added to amplitude limit and frequency discrimination level 41, the modulated of the colourity of intermediate-freuqncy signal and brightness video component is by demodulation in 41, in its output, produce baseband video signal MAC, in the level 42 of postemphasising to the signal processing of postemphasising.Amplitude limit and frequency discrimination level 41 produce a.f.c. voltage, and it is delivered on the add circuit 37 through 38.

Intermediate-freuqncy signal also is added on amplitude limiter and the 2-4PSK demodulator 43, and data pulse string in 43 (sound/data component) and other the digital information on 20.25M bit/s all have been resumed out.These digital signals are delivered on the converter 44, and converter 44 has many functions, and one of them is the bit that replaces that launches sound/data digital signal, makes their bit rate fall very lowly.Fig. 9 has at length provided some feature of converter 44.The digital information of 20.25M bit/s is added in the input 52 of converter 44 in Fig. 9, it can be used as the input of pulse generator 45, pulse generator produces desired various clock frequencies of circuit and various read-write control signal, and these read-write control signal also are that converter 44 proper operations are necessary.In order to receive 196 sound/data bits of every row, its clock rate is C1 20.25MHz, and 52 input is also delivered on the shunt circuit 46 simultaneously.Under the control of second clock frequency C2 10.125MHz, the output of shunt circuit 46 is the pulses from the next alternate of input data, promptly only is bit of ' A ' group or the bit of ' B ' group, as shown in Figure 6.The output of supposing shunt circuit 46 only comprises ' A ' bit, it is added on a latch and the delay circuit 47, at this moment the length of each bit is doubled and as described below, they will have a very short time delay, and circuit 47 also receives the clock signal C2 of 10.125MHz.

Data on the terminal 52 are also delivered on the fifo circuit (FIFO) 48, regulation L624/625 is FIFO, circuit is operated the valid data in every frame the 624th and 625 row, taking-up is adapted at the data division that transmits on the low rate of 10.125M bit/s, and FIFO receives C1 and C2 clock by its frequency separately.Terminal 52 also is connected with synchronous circuit 49, it extracts synchronizing information from the capable synchronization character that receives under the control of clock frequency C1 and C2, known that the predetermined sequence of synchronization character just can produce the suitable synchronization character of each row on the desirable time, its speed is 10.125M bit/s.Below this point to be described, please refer to Figure 10.Synchronous circuit 49 also produces timing controling signal from input the synchronization character, and its is through line 50 another input as pulse generator 45, and it is the appearance of the read-write that produced of control impuls generator accurately.

The output of latch and delay circuit 47, the output of L624/625FIFO48 and synchronous circuit 49 all links to each other with the input of Port Multiplier 51 respectively, the control of the control signal by pulse generator 45, its produces the data of data pulse string and row 625, and their speed is half of speed of C-MAC packet group.Speed in the output 53 is 10.125M bit/s.With regard to the data on these row, how to realize the data of ' A ' and ' B ' Port Multiplier are sent out, we can be illustrated with corresponding clock Figure 10.Figure 10 has at length provided certain part of adjacent lines, it consists of the following components: be transformed into 5 sampling periods (h) that data begin, 204 bits synchronously and sound/data (pulse train) (a) be converted to 5 sampling periods (b) of end with data, the speed of all these is 20.25M bit/s all, referring to Fig. 1.204 bits synchronous and data/sound are serial numbers, represent to enter synchronously bit 2-8(S with the bit of R mark) the corresponding 7 bit-rows synchronization characters of formation.From 9 to 204 remaining bits carry sound/data-signal with band, and its odd number bit is loaded with the data of ' A ' group information source, and even bit then is the data of ' B ' group.For a certain definite modulation format, cycle might not be needed (h) and (b) as conversion, it also can the switching signal form be loaded with data like this, if bit rate reduces by half, bit number can be increased to (h+a+b)/2=214/2=107 from a/2=204/2=102, concerning synchronization character, might not transmit entering (Run-in) bit R and just might be used for valid data to 98 bits.The transmission of data now can be since the cycle (h) initial, but can see from Figure 10 a, the synchronization character of the row that we were concerned about just began afterwards in the cycle (h), this problem can overcome with the capable synchronization character that is produced by synchronous circuit 49, and (this point was done introduction with entering bit (run-in) in front) is shown in Figure 10 b.The numbering of bit is consistent with the numbering of the bit of the data pulse string of Figure 10 a in Figure 10 b.Latch and delay circuit 47 blockades or broadening are from each ' A ' bit of splitter 46, and producing speed is ' A ' bit pulse string of the broadening of 10.125M bit/s, and on this speed, it has the time delay of 1 bit period.First broadened ' A ' bit be along with the 7th broadening of front bit sync word, this ' A ' bit is designated as A9, it has indicated that the reception of input data bit begins with it, this also can use on other ' A ' bit.Last ' A ' bit (A201 and A203) is as backup in the data, and it can expand in transformation period (b), and the width in cycle (b) is half of cycle of broadening.So as can be seen, going synchronization character and data ' A ' bit fully can be by cycle (h), (a) and (b) hold.

Except receiving the data in terminal 52, L624/625FIFO 48 also receives the output S of synchronous circuit 49.FIFO is the capable synchronization character of broadening suitably, it can be used with row 624/625, and it is positioned the section start of broadening capable 624/625, and it will partly start in the beginning in cycle (h).What relation is the data of coming from these row do not have with the row of front, it be simply with broadening speed read in the first in first out unit, this just means that it can not comprise all data in 624 and 625 of may being expert at that occur with the broadening form.By the discussion of front, suggestion is revised row 624 and 625, so even without valid data in these row, do not had what problem yet.In line period, make broadening, static data frame (SDF) is moved on to the 624 valid data parts of going, in 624 row, also will allow to hold frame synchronization data (FSD), unified data and time standard (UDT) and the frame data (RDF) that repeat.

Except the top output 53 by converter 44 generations, another output 54 has provided the clock pulse of a 10.125MHz.

Referring again to Fig. 8, the modulation input of delivering to modulator 55 from level 42 vision signals that obtain of postemphasising, on carrier wave, this carrier wave is from carrier oscillator 56 by amplitude modulation(PAM) for signal in modulator, and it is as second input of modulator.The frequency of carrier wave is in the frequency band range that adopts at cable communication system.The output of modulator 55 is added to first input of Port Multiplier 57, and for signal is delivered to cable communication system, the output of Port Multiplier 57 is added in the output 59 of power converter cells by vestigial sideband filter 58.

The digital signal that transmits broadening respectively is added on the digital modulator 60 with the converter terminal 53 of relevant clock frequency signal (10.125MHz) and 54 output, and another input of modulator 60 is to receive the carrier signal of coming from carrier oscillator 56.In modulator 60, the digital signal digital modulation that carrier wave is broadened, it can be the duobinary system modulation format, is added on second input of Port Multiplier from the transferred signal of modulator 60, then signal is delivered on the outlet terminal 59 by filter 58.

For only transmitting the continuous receiver of cable system of ' A ' group data, the receive mode that is used in the C-MAC packet group receiver that provides in the reception of data-signal and the suggestion in the existing transmission system does not have any very big difference, and the speed of C-MAC reduces by half.Directly the receiver from satellite reception data-signal requires that a splitter is arranged, and it will be divided into two groups ' A ' and ' B ' to data again.Its advantage is that signal is changed to (10.125MHz rather than 20.25MHz) on the lower speed, and the data processing ratio is easier to.Utilize following method can obtain being used for the reference receiver of the dual work of cable/satellite easily,, and between satellite and the branch circuit-switched data that obtains from cable, be added with suitable switch promptly by top said the need with two data demodulators.

The output bit flow of Port Multiplier 19 is to constitute with the form of a series of individual bit data sets in the concrete equipment in front.Very clear, can use the many bits that produce by same Port Multiplier to constitute each data set.

Claims (6)

1, in a kind of television transmission system of time-division multiplex signal, the main signal form of row is a time-division multiplex in its frame period, it includes digital data pulse string component and video component, data in the data pulse string component are from many different information sources, from each information source, they are all formed the pulse group by time-division multiplex, comprise a plurality of predetermined data bits in the data pulse string, system is characterised in that, described information source can be divided into N information source group, the data of coming from the information source of each information source group are with the form time-division multiplex of a series of bit pulse group, they form N son-multiple signals with the form of data bit flow, the data pulse string that from N data bit stream each is come forms the data bit of corresponding line, and the bit number in data pulse string is the integral multiple of information source packet count N.

2, by the described television transmission system of claim 1, it is characterized in that, described information source is divided into two groups, the consecutive line of each data pulse string always with two groups in first bit together begin.

3, include the video source that forms the time-division multiplex vision signal by the transmission of television machine equipment that is adopted in arbitrary above-mentioned described television transmission system of claim, many information sources of sound/data-signal, it includes device that sound/data-signal is handled as digital signal and digital signal is made the device that time-division multiplex is handled by the form of series of pulses group, the time-division multiplex signal is in TV signal data pulse train component, described data pulse string component comprises a plurality of predetermined data bits, the transmission of television machine equipment is characterised in that, is that the described information source of sound/data-signal is divided into the N group; The signal that its handlebar comes from each information source group carries out the device that time division multiplexed is handled with the form of a series of bit pulse group, and it forms N son-multiple signals with the form of data bit flow; Each device of choosing bit and described bit layout being become described data pulse string from N bit stream is arranged, it makes the bit that includes in the corresponding line of data pulse string from N bit stream to come in each, and the bit number in data pulse string is the integral multiple of packet count N.

4, by the described transmission of television machine equipment of claim 3, it is characterized in that, described sound/data source is divided into two groups, and described choice device is chosen bit from each information source group, and each data consecutive line first bit in described two groups is begun.

5, the TV receiving apparatus that is adopted by claim 1 or 2 described television transmission systems includes in order to receive the device of described TV signal, in order to from described TV signal, to separate the device of described video component, with the device that from described TV signal, produces data pulse string, receiving equipment is characterised in that adding in the described receiving equipment has the device of choosing bit from the data pulse string of representing certain specific described information source group.

6, include by the described TV receiving apparatus of claim 5 described video component is modulated at device on the carrier wave again, its carrier bandwidths is littler than the bandwidth of the described signal that receives, TV receiving apparatus is characterised in that, further provide in order to the described bit that comes from a described information source group being formed the device of a data pulse string that has improved, this data pulse string that has improved comprises and equals original a plurality of a plurality of data bits divided by group number N; And data pulse string is modulated on the carrier wave device that forms another time-division multiplex TV signal, the data pulse string that this time-division multiplex TV signal comprises the video component of described limited bandwidth and improved.

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