CN1108448A - System for transmission of digital sound and data via satellite TV system - Google Patents
System for transmission of digital sound and data via satellite TV system Download PDFInfo
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- CN1108448A CN1108448A CN 94102206 CN94102206A CN1108448A CN 1108448 A CN1108448 A CN 1108448A CN 94102206 CN94102206 CN 94102206 CN 94102206 A CN94102206 A CN 94102206A CN 1108448 A CN1108448 A CN 1108448A
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Abstract
The digital voice and data transmission system for satellite TV system includes video processing unit, audio processing unit, mixer which mixes the video and audio subcarrier signals, subcarrier modulator, 70 MHz modulator, up converter, power amplifier circuit, transmitting unit comprised of duplexer and transmitting antenna, receiving unit comprised of receiving antenna, low noise down converter and satellite receiver. The characteristic is the addition of NICAM-728 code modulator in the transmitting unit, which code-modulates two voice signal inputs and sends out 7.28 MHz signal to the mixer, the receiving unit is also added with NICAM-728 digital voice receiver, which receives base band output signal from the satellite receiver and demodulates into two channels of voice signals.
Description
The present invention is a new system and method that transmits digitized voice and data in the satellite repeater that transmits TV.
A lot of in the mode of utilizing satellite repeater transmission TV programme and multiple sound in the world at present.But be applicable to that China requires, promptly will with original transmission of television means compatibility, the system that can transmit high-quality digitized voice of multichannel and data message again comes out before this as yet.
The present invention proposes in order to adapt to this requirement exactly, and obtained the system that reality has proved.
The invention reside in the image that keeps in the original satellite television transfer system and the transmission means of television field frame, increase a process again and select the subcarrier of frequency parameter meticulously, on this subcarrier, adopt the NICAM-728 mode, be used for transmitting two cover monophone broadcast programs or a cover stereophonic program or a data message.
The NICAM-728 mode be by Britain BBC research in order to carry out a kind of coded system of the two sound accompaniments of ground TV broadcast, the theory diagram of this coded system is as shown in Figure 1.The left and right sound channels signal of a two-way sound broadcasting signal or a cover stereophonic program is delivered to A/D converter through preemphasis J.17, A/D conversion output is through 14/10 bit compression, and increase a bit and be used for parity check, in the Bit Interleave level, data are interweaved according to certain rules, data after interweaving and pseudo-random binary sequence mould 2 add, to reach the purpose of energy dissipation.Above-mentioned processing procedure division is as follows:
1.A/D conversion
For satisfying the sound bandwidth of 15KHz, then sampling frequency is elected 32KHz as.For satisfying the requirement of quantified precision, then quantize to adopt 14 bit/samplings.
2. nearly instantaneous companding
For compression bit rate, adopt the nearly instantaneous companding technology with every sample value by 14 bit compression to 10 bits.Its compression method is that adjacent 32 sound sample values are formed a code block (time 1ms), according to five coding range of 32 sampling value amplitude definition, the highest significant position of each sampling value is not done compression and is handled, 13 remaining bits are according to the difference of coding range, the processing that a high position or house low level are lost in employing is compressed to 9 bits, add highest order, the sample value after then being compressed is 10 bits.At receiving terminal,, must rely on the scale factor that characterizes coding range in order to recover the bit that these are lost house.
Each 10 bit sample value for after the compression for improving its anti-error code capacity, add 1 bit parity sign indicating number in the back, it with 10 bits in the parity check of preceding 6 bits (being high order bit) compositions.Like this, each sample value comprises 11 bits, and when actual transmissions, utilizes this parity code to hold concurrently again and transmit the effect of scale factor code, promptly so-called SIP(Signalling-in-parity) technology.
3. frame structure
Two-way sound code is formed independent a string data flow it is formed a framing structure that includes frame alignment word and control code etc.Frame structure comprises 728 bits in its each frame structure as shown in Figure 2, and the time of 1 frame is 1ms.It is constructed as follows:
Frame alignment word: 8 bits
Control information: 5 bits
Additional data: 11 bits
Sound/data set 704 bits
704 bit sound/data sets are made up of 64 11 bit sound sign indicating numbers, and when transmission was stereo, every group of A, B passage accounted for 32 sample values, alternately transmitted, shown in Fig. 2 (a).When transmitting the two-way monophone, each 32 sample value of two sound channels are end to end in a frame, shown in Fig. 2 (b).
Preceding 8 bits of every frame are frame alignment word, and the decoding when being used to receive is synchronous.Thereafter 5 bits are control information, and its 1st is flag of frame position C
o, preceding 8 successive frame C
oBe 1, back 8 successive frame C
oBe 0, like this, one circulation of 16 frames.Transmitted breath type is that unit carries out if will change (stereo, two-way monophone, data etc.) with 16 frames in the passage.The the 2nd to 4 (C of control information
1, C
2, C
3) then showing the type of sound/data in existing 704 bits, its regulation is as follows:
Control code C
4Effect be: as frequency modulation sound accompaniment and stereo or monophone M
1When programme content is identical, C then
4Be 1, otherwise C
4Be 0.Like this, when the digital sound passage breaks down, at C
4Be 1, then the output of frequency modulation sound accompaniment replaces the digital sound sound accompaniment automatically.At C
4Be 0 o'clock, then do not carry out this automatic switchover.
Additional data AD
0～AD
10, do not make concrete regulation as yet, give in the future and use.
4. Bit Interleave
For alleviating the influence that error burst causes in the transmission, and adopt the Bit Interleave means, the sound/data of 704 bits are carried out interleaving treatment, the mode of the Bit Interleave of Cai Yonging is as follows here:
5. energy dissipation scrambling
For the purpose of spectrum shaping, make signal energy not concentrate on local frequency range, be to realize with pseudo-random binary sequence mould 2 Calais and adopt energy dispersal technique, this technology by data flow (except that frame alignment word) with frame structure.
6. modulation system
Modulation system adopts the DQPSK modulation.Its processing procedure is as follows: the serial data stream after energy dissipation at first carries out serial/parallel conversion, become two parallel-by-bit sign indicating numbers, parallel dicode unit modulates the phase place of two quadrature carriers after differential coding and shaping filter processing, and its orthogonal demodulation signal linear, additive has promptly been finished the DQPSK modulation.
The basic coding and the modulated process of NICAM-728 mode have more than been sketched.And this mode only is used for the television broadcasting on ground at present in the world.Even so, the ground TV broadcast of relevant PAL-D/K system does not still have the application standard of NICAM-728 mode, the television broadcasting on ground, the selection of the modulation system of its image and sound subcarrier frequency, and picture-and-sound radiation pattern etc. all is different from the transmission of television of satellite.
In the existing satellite television transfer system, only transmit one tunnel picture signal and one tunnel audio signal.The frequency spectrum of its baseband signal as shown in Figure 3, its system block diagram is as shown in Figure 4.
The objective of the invention is increases by second subcarrier that a process is selected frequency meticulously in existing satellite television transfer system, adopt above-mentioned NICAM-728 mode, finishes the transmission of two cover monophone broadcast programs or a cover stereophonic program or data message.
Fig. 1 is the NICAM-728 encoder block diagram.
Fig. 2 is a NICAM-728 coded frame structure chart.
Fig. 3 is existing satellite television transfer system baseband frequency spectrum figure.
Fig. 4 is existing satellite television transfer system block diagram.
Fig. 5 is satellite television transfer system baseband frequency spectrum figure of the present invention.
Fig. 6 is a satellite television transfer system block diagram of the present invention.
Fig. 7 is NICAM-728 digital sound receiver block diagram in the satellite television transfer system of the present invention.
Fig. 8 is NICAM-728 digital receiver Control Software flow chart in the satellite television transfer system of the present invention.
System of the present invention base-band signal spectrum as shown in Figure 5, its system block diagram is as shown in Figure 6.As seen, compare with existing systems from system block diagram, this NICAM-728 coding, modulator and NICAM-728 digital sound receiver are the parts that the present invention increases.
Can the key point here be realizing of whole proposal, depends on second subcarrier that is increased, i.e. the frequency of NICAM-728 coding, the selected subcarrier of modulator, and to the selection of the modulation depth (being frequency deviation) of satellite uplink main carrier.
The countries concerned's standard that existing satellite television transmits all can not be changed the frequency deviation of satellite uplink main carrier etc. comprising picture signal and sound subcarrier signal.On this basis, the frequency of selected second subcarrier and second subcarrier promptly will satisfy the requirement of the bandwidth of the bandwidth chahnel of upstream plant and satellite receiver to the frequency deviation of main carrier, will guarantee that also the signal of second subcarrier can not influence the delivery quality of the picture-and-sound of existing TV.Now the selection of the frequency of second subcarrier and second subcarrier signal selection key point to the frequency deviation of main carrier is described as follows:
1. the selection of second subcarrier frequency
In the transmission system of satellite television, as can be seen from Fig. 3, the picture-and-sound subcarrier has accounted for the frequency band of 0～6.6MH, and 8.4MHz demarcates in the modulating system baseband bandwidth state of satellite uplink.The first subcarrier 6.6MHz is a FM signal, bandwidth pact ± 100KHz own.The frequency of second subcarrier, we are chosen to be 7.28MHz, and it is 10 times of bit rate 728kb/s.This 7.28MHz subcarrier signal is a signal that is adopted the DQPSK mode to modulate by the data flow of 728kb/s.The rolloff-factor of the forming filter here elects 100% as, and then the signal bandwidth after the modulation is about ± 200KHz.Say that from frequency interval the 7.28MHz of the 6.6MHz of first subcarrier and second subcarrier is suitable.Wherein, the selected principle of cosine roll off coefficient is under the situation that transmission bandwidth allows, to select bigger rolloff-factor as far as possible, though this be because the bandwidth of big rolloff-factor frequency spectrum can be than little rolloff-factor wide, help the receiving demodulation after the signal transmission.Through to the analytical calculation of frequency interval and relevant signal spectrum, the selection rolloff-factor is 100% to be rational.
2. second subcarrier signal is to the selection of main carrier frequency modulation
The basic principle that this frequency deviation is selected is: because the existing image and first sound subcarrier are to the frequency deviation of main carrier, the existing regulation of national standard (seeing GB11444.3), this is unalterable at present, and the selection of second subcarrier (7.28MHz) the frequency deviation size that increases newly promptly will must not guarantee and influenced the existing image and the first subcarrier Television Sound Quality, guarantee the delivery quality of the signal of second subcarrier itself again, promptly satisfy the requirement of the error rate.The two is conflicting, because collateral security second subcarrier itself transmits signal quality, wishes that its frequency deviation selects greatlyyer, and is favourable to the transmission of second subcarrier signal.And, wish that then its frequency deviation selects lessly from of the influence of second subcarrier signal for the picture signal and the first subcarrier audio signal, then influence is also little.This just need obtain best frequency deviation by a large amount of transmission tests.
For the frequency of verifying selected second subcarrier whether rationally and select the best frequency deviation of second subcarrier signal to main carrier, in breadboard Satellite Simulation transmission system, done the test of various frequency deviations, from 3MHz
P-pTo 5.5MHz
P-pBetween, every interval 0.5MHz
P-pDo a kind of frequency deviation test.On the basis of laboratory simulation transmission test, repeatedly do actual open circuit transmission test again at the satellite uplink station, the data of laboratory simulation test are verified.These tests comprise:
1. during the size of different frequency deviations, different reception antennas (2M, 3.2M, 4.5M, 5M), second subcarrier signal is to the influence of the image and the first subcarrier sound accompaniment.
2. when different frequency deviations, different reception antenna size (2M, 3.2M, 4.5M, 5M), the picture signal and the first subcarrier audio signal are to the influence (mainly being the influence to the error rate of second subcarrier signal here) of second subcarrier signal.
From various result of the tests, verified that selected second subcarrier frequency is that 7.28MHz is rational, it is suitable that the cosine roll off coefficient of its modulation signal forming filter is chosen to be 100%, and preferred second subcarrier signal is 4.5MHz to the frequency modulation of main carrier signal
P-p
In order further to verify selected various parameters, done the expansion acceptance test in five provinces in the whole nation again, what especially have outstanding meaning is the Heihe Area of Heilongjiang Province, its geographical position is the field intensity district, border of used " No. five, the culminant star " satellite of first and second programs of the Chinese Central Television (CCTV) just, receives well with the 4.5m antenna.
In whole system, one of them key equipment is at receiving terminal, and the special-purpose NICAM-728 digital sound receiver that we develop is truely used novel patented product.The specific satellite television channel subcarrier that is applicable to this new product transmits NICAM-728 digital sound system.Be characterized in: band pass filter (141) extracts the NICAM-728 signal from the satellite television base-band signal spectrum, after preamplifier (142) amplifies, demodulating frequency by DQPSK demodulator (143) is 7.28MHz, the DQPSK modulation, the cosine roll off coefficient is 100% NICAM-728 signal, the NICAM-728 signal is decoded as digital audio signal through decoder (144) with it, D/A converter (145) is transformed to analoging sound signal with digital audio signal, then, deliver to amplify and go heavy filtering stage (146), through J.17 going heavily, low-pass filtering and uneven to balanced transformation, output to driving stage (147), export the two-way voice signal at last.Computer and display control section are finished I under specific software is supported
2C Bus simulator, decoding chip initialization, Error detection and outputting alarm signal.The block diagram of its receiver as shown in Figure 7, its Control Software flow chart is as shown in Figure 8.
In sum, the invention has the advantages that, in the satellite uplink system of existing transmission TV, only do change seldom, increase few investment, just can utilize more fully the frequency spectrum resource of satellite repeater, improve the availability of frequency spectrum of satellite repeater. At receiving terminal, at the existing Satellite Receiving Station that receives TV, only need increase a NICAM-728 numeral sound reception machine, can obtain the high-quality monophone broadcast program of two-way or the stereo program of cover or a data information. Whole system can solve the high-quality transmission of broadcast program with seldom investment, for the covering that improves broadcast program, improves the delivery quality of broadcast program, has very actual significance.
Claims (3)
1, a kind of system that in satellite TV system, transmits digitized voice and data, it comprises by video processing unit (1), sound accompaniment processing unit (2), the blender (4) that above-mentioned video and sound subcarrier signal (subcarrier frequency is 6.6MHz) are mixed, TV subcarrier modulator (5), 70MHz modulator (6), upconverter (7), power amplifier (8), the radiating portion that duplexer (9) and transmitting antenna (10) etc. are formed, and by reception antenna (11), the receiver section that low noise block downconverter (12) and satellite receiver (13) are formed, it is characterized in that: in radiating portion, increased NICAM-728 coding demodulator (3), it carries out coded modulation with the input of two-way voice signal, and the signal of output 7.28MHz is given blender (4); Correspondingly also increased NICAM-728 digital sound receiver (14) at receiving unit, it receives baseband output signal from satellite receiver (13), and solves the two-way voice signal.
2, according to the transmission digitized voice in satellite TV system of claim 1 and the system of data, it is characterized in that the frequency by second subcarrier of NICAM-728 coding demodulator (3) output is 7.28MHz, it is 10 times of bit rate 728kb/s, adopt the DQPSK mode that this second subcarrier is modulated, signal bandwidth after the modulation is about ± and 200, the rolloff-factor of its forming filter is 100%.
3,, it is characterized in that said NICAM-728 digital sound receiver comprises band pass filter (141), placement amplifier (142), DQPSK demodulator (143), NICAM-728 decoder (144), D/A (145), amplifies and remove heavy filtering stage (146), balance out drive stage (147), CPU(148 according to the system that in satellite TV system, transmits digitized voice and data of claim 1) and display driver (149) etc.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94102206A CN1035918C (en) | 1994-03-10 | 1994-03-10 | System for transmission of digital sound and data via satellite TV system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN94102206A CN1035918C (en) | 1994-03-10 | 1994-03-10 | System for transmission of digital sound and data via satellite TV system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1108448A true CN1108448A (en) | 1995-09-13 |
| CN1035918C CN1035918C (en) | 1997-09-17 |
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ID=5030559
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN94102206A Expired - Fee Related CN1035918C (en) | 1994-03-10 | 1994-03-10 | System for transmission of digital sound and data via satellite TV system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1035918C (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8414665D0 (en) * | 1984-06-08 | 1984-07-11 | Philips Electronic Associated | Television transmission system |
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1994
- 1994-03-10 CN CN94102206A patent/CN1035918C/en not_active Expired - Fee Related
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| Publication number | Publication date |
|---|---|
| CN1035918C (en) | 1997-09-17 |
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