RU2163420C2 - Method for shaping dual-channel audio signals including stereo ones, broadcasting signals, control data and commands in sound diffusion and cable networks (alternatives); multichannel audio signal transmission, broadcasting, control data and command transmission system in sound diffusion and cable networks - Google Patents

Abstract

FIELD: radio engineering. SUBSTANCE: novelty in transmitting television-program audio signals using SECAM system over existing radio channels jointly with computer data or translation signals and broadcasting signals is that audio signals are coded using MUSICAM system . Chosen data-transmission format is used in multiplexing coded signals, data interlacing is introduced for digital error protection of burst, noise-protected digital audio data stream is modulated by four-position phase keying of carrier. EFFECT: improved quality of television-program audio signals. 3 cl, 2 dwg

Description

 The invention relates to the field of digital coding and data transmission for the organization of digital sound channels for television or broadcast programs and digital channels for the exchange of information between databases, servers and personal computers by transmitting data (including sound data) together with radio signals from television programs, over the air and cable television networks.

 The subject of this work is the creation of a method for joint transmission of an additional digital data stream over existing radio channels of on-air and cable television in the process of broadcasting television programs according to the radiation standards of SECAM CTs - D, K and L (hereinafter referred to as SECAM CTs) with the organization, firstly, of two-channel, including stereo, sound accompaniment for the SECAM DT system or broadcasting signals and, secondly, data transmission systems and control commands for the exchange of information between databases, servers and personal computers.

 In the SECAM central heating system operating in the territory of the Russian Federation, a monophonic sound signal is transmitted on a separate carrier by its frequency modulation. It is possible to expand the functionality of TV broadcasting, firstly, by transmitting stereo audio signals and, secondly, data and control commands for creating multimedia systems with an order (for example, over the telephone network) by the viewer of additional services and information on demand.

 In previous decades, the development and testing of several stereo sound systems in television was carried out. An analog system with polar modulation (like VHF FM) did not have sufficiently high-quality indicators. The NICAM digital system, developed for the PAL DT system [1,2] and adopted as a prototype of the utility model, cannot be combined with the SECAM DT system, which has a frequency band of the image signal of 6 MHz, without significant reduction of the latter, which significantly reduces both the brightness and color sharpness of the image. Thus, the problem still has not found a solution. The present invention addresses this problem.

 The technical implementation of a digital sound system for broadcasting and cable broadcasting will provide the public with the possibility of receiving high-quality stereo digital soundtrack (SCZS) TV programs in the SECAM DT system over existing radio channels.

 In addition, in connection with the massive introduction of personal computers (PCs), a new type of service began to develop rapidly - the receipt of various types of information materials, certificates, data for PC users. For these purposes, information is ordered that is ordered via the INTERNET network, as well as information received from servers of other information systems. At the same time, channels of the existing telephone network are used to order and transmit information material, to which personal computers are connected via modems.

 The use of a telephone network for data transmission leads to the following disadvantages. First of all, a low data transfer rate is ensured, which when working on dial-up subscriber telephone channels is 1.2 ... 9.6 kbit / s. For this reason, the transmission time of the ordered file to the PC user can be tens of minutes or more, which significantly exceeds the average channel busy time during a telephone conversation. As a result, as computer services develop, it will become harder and harder for subscribers of such a telephone network to reach each other because of the constant use of telephone channels by PC modem signals.

 The technical implementation of the proposed data transmission system for radio channels of on-air and cable television will significantly increase the speed of their transmission, thereby reducing the transmission time of ordered files by 10 ... 20 times and reduce the load on telephone channels.

 Intensive work in the world to improve digital audio compression methods has led to the development of the MUSICAM digital system, which is approximately 2.8 times more efficient than the NICAM system in compressing the sound stream. This makes it possible to realize the transmission of digital sound accompaniment to the consumer with full preservation of the quality of the video signal of the image, together with the sound accompaniment on the frequency-modulated carrier system of the DEC SECAM.

 The MUSICAM system passed international comparative tests, during which it was found that, compared to other digital coding systems, it provides the best subjective sound at digital stream speeds of 196, 128 and 96 kbit / s per mono channel. It was she who formed the basis of a single world standard for a system of high-quality low-speed coding of broadcasting signals and sound accompaniment ISO / IEC 13818-3. For digital sound systems, the so-called II level of quality is used at speeds of 192 kbit / s per channel (inter-studio exchange with subsequent processing), 128 kbit / s (distribution to transmitting TV stations without further processing) and 96 kbit / s for broadcast and wire broadcasting sound programs.

 The results of studies conducted by the applicant showed the feasibility of SCSS via the MUSICAM system with a sound delivery rate of 256 kbit / s to the stereo pair to the end user), which means an additional margin of quality relative to the recommended standard. In this case, the subjective perception of stereo sound is indistinguishable from the sound of a CD when playing any, including music program. In addition, the sound channels are absolutely independent, which allows them to be used not only in stereo sound mode, but also as separate ones, for example, for bilingual sound.

 At the same time, it is possible to increase the number of sound channels several (4 ... 8) times and use them to transmit sound translations in 4-8 languages.

 This is achieved by switching the MUSICAM-1 and 2 encoders using control signals (SU-1 and SU-n) from stereo soundtrack mode to sound transmission mode in several languages, or commentary channels. At the same time, the audio data transfer rate for one MUSICAM encoder can be reduced from 128 kbit / s to 32 - 64 kbit / s.

 Note that the transmission mode of these channels is the standard mode for the MUSICAM encoder and is provided by the ISO / IEC 13818 standard.

 As a result, 256 kbit / s (32 ... 64) = 8 ... 4 commentary channels can be organized in a 256 kbit / s digital stream.

 Other uses for the 256 kbps stream are possible. For example, use 196 kbit / s for the transfer of SCSs, which meets the requirements of the standard for DSS systems for broadcasting and wire broadcasting of sound programs, and 64 kbit / s for transmitting data and control commands to PC users. In addition, it must be borne in mind that in real TV broadcasts there is program material that can be transmitted with standard monophonic sound accompaniment. For example, the transmission of the latest news, weather forecasts, etc., during the transmission of which it is enough to transmit monophonic sound, and at time intervals, you can stop the transmission of audio data and use the entire digital stream 256 kbps to transfer computer data to PC users . Note that there are other options for the dynamic distribution of the capacity of the digital stream between audio and computer data, depending on the specific conditions of application of this system.

 In FIG. 1 is a structural diagram of a system including a transmitting and receiving device that implements a method for generating and transmitting sound signals, broadcasting, data and control commands as part of the radio spectrum of the TV program CT SECAM in broadcast and cable broadcasting networks.

 Figure 2 presents the radio spectrum of the signal generated in accordance with the claimed method.

 The transmitting device comprises the first and second MUSICAM encoders - 1,2, the interface unit 3, the multiplexer 4, the scrambler 5, the channel encoder 6, the modulator 7, the mixer 8, the local oscillator 9, the power amplifier 10, the synchronization unit of the transmitting part 11; on the receiving side there is a high-frequency amplifier 12, mixer 13, local oscillator 14, intermediate-frequency amplifier 15, demodulator 16, channel decoder 17, descrambler 18, demultiplexer 19, first and second decoders, MUSICAM - 20, 21, interface unit 22, synchronization block receiving part 23.

 The choice of mode: the transmission of audio data or computer data, or the joint transmission of audio and computer data with different ratios of video and audio data rates is carried out by applying to the control input 5 (VU) of the multiplexer the corresponding commands from an external control device, such as a remote control or computer control complex.

 Initially, we consider the formation of data in a two-channel mode, including stereo sound.

 A device for digital data transmission as part of the radio spectrum of the TV program of the CT SECAM system works as follows. Stereo audio signals or audio signals in different languages, or broadcasting program signals in accordance with the selected transmission mode are fed to inputs 1 and 2 (ZS-1 and ZS-2) of two MUSICAM encoders. From the outputs of two encoders, audio data are fed to two inputs of the multiplexer (MUX).

 When multiplexing, one of the generally accepted data transmission formats can be used, for example, the sound transmission format of the European telecommunication standard ETS 300 401 "Broadcasting systems; digital sound broadcasting (DAV) for automotive, portable and stationary receivers", or the sound data transmission format of the international standard for digital sound signals accompanying ISO / IEC - 13818-3. Further consideration of the operation of the device will be carried out on the example of the data transmission standard ISO / IEC - 13818-3.

 In this case, continuous streams of audio data from each sound encoder are converted into MPEG-2 transport packets of 188 bytes in duration, of which 4 bytes (packet header) are used to transmit service information, including: synchronization signals of the demultiplexer and the MUSICAM decoder, recognition signals of the type of transmitted information. It is indicated that at the moment, for example, transmission of sound signals of television or signals of broadcasting programs, or computer data, or other types of information, as well as possible combinations of these transmission modes, is being carried out. These signals also indicate additional data. For example, it is indicated that sound is being transmitted in stereo or in monaural in two languages. Similarly, when transmitting signals of radio programs, the transmission mode is also indicated: for example, the transmission of one radio program in stereo mode or two different radio programs in monophonic mode.

 Service information is also transmitted in the packet header: the used speeds of the digital streams, synchronization and control signals of the receiving device and other necessary signals (including, in particular, the packet identification signal), which are entered into the digital stream in encoders (1,2, ..., n) MUSIC and in the interface unit. The remaining 184 bytes of the packet are used for data transmission, while only one type of information is transmitted in one packet. After such processing, the digital stream from the output of the multiplexer is fed to the input of the scrambler.

 Further functional units of the digital data transmission system of figure 1 are common to the transmission modes of sound and computer data and it is advisable to return to them after considering the transmission mode of computer data.

 The transition to the computer data transmission mode is carried out by transmitting the corresponding command (code word) to the control input 5 of the MUX multiplexer (see figure 1). In this case, the internal circuits of the MUX multiplexer are switched, as a result of which the data from the output of the interface device-1 goes to the multiplexer circuit, and the audio data from the outputs of the encoders 1 and 2 of the MUSIC is disconnected from the multiplexer. Other combinations of sound data and computer data transmission modes are also possible, in which the total digital stream is formed by multiplexing the sound data and data from the outputs of the MUSICAM encoders 1 and 2 and the interface device 1.

 The digital stream of sound data and / or data and control signals of the receiving device formed in the multiplexer is fed to the input of the scrambler.

 Scrambling is introduced to eliminate the long series “0” or “1” in MPEG-2 transport packets, which ensures stable operation of the clock synchronization system of the receiving device. In this case, in order not to disrupt cyclic synchronization in the demodulator, the start groups of MPEG-2 transport streams are not scrambled.

 The digital audio stream from the output of the scrambler goes to the input of the channel encoder. The goal of channel coding is to increase the noise immunity of the digital sound system and to match the parameters of the digital sound data stream with the energy and physical characteristics of the broadcast and cable channels of the TV broadcast. In this case, the digital audio stream is subjected to two-stage noise-resistant coding. In the first stage, noise-resistant coding is performed by the Reed-Solomon code to protect against single digital errors, in the second stage, the audio data is interleaved and convolutionally noise-resistant coding for protection against digital packet errors.

 The data processing cycle in the channel encoder is synchronized with the transmission frequency of MPEG-2 transport packets and includes a group of 8 transport packets of 188 bytes each. To introduce a cyclic synchronization signal in the first transport packet of the cycle, the signals of the starting synchronization group of the packet are inverted. In the remaining seven transport packets of the cycle, the start sync groups are not inverted.

 Interference-tolerant coding of MPEG-2 transport packets is carried out together with the starting synchro-groups of packets and is performed by the Reed-Solomon code (204. 188. 8), which allows you to correct 8 digital error packets of 1 byte size. After this encoding, the duration of the transport packet increases from 188 to 204 bytes.

 To protect against digital error packets larger than 1 byte, data interleaving is introduced. For this purpose, two adjacent bytes of the transport packet are rearranged to an interleaving depth of 12 bytes. At the same time, in order not to disrupt cyclic synchronization in the receiving device, the starting synchro groups in transport packets are not interleaved and remain at their temporary positions.

 To further reduce the digital error rate, a second code protection level can be introduced. At the same time, transport packets after interleaving data undergo noise-correcting coding with a convolutional code.

 From the output of the channel encoder, the noise-protected digital stream of sound data, data and control signals of the receiving device is fed to the input of the phase modulator, in which the four-position phase shift keying of the carrier is performed.

 The carrier modulated by the digital signal is fed to the first input of the mixer, to the second input of which the signal from the local oscillator is applied. In the mixer, the carrier radio spectrum is transferred to the desired frequency radio channel on the air or cable TV broadcasting network.

 From the output of the mixer, the radio signal is fed to the input of the power amplifier, in which the power of the radio signal is amplified to the desired value. From the output of the power amplifier, the radio signal is either transmitted to the transmitting antenna of the telecentre in the case of broadcasting, or to the headend of cable television for transmission via cable network.

 For the functional blocks of the transmitting device to work together, synchronization and control signals are required. These signals are generated in the synchronization block (see Fig. 1) and are distributed among the functional blocks.

 On the receiving side, the radio signal from the receiving antenna in the case of terrestrial TV broadcasting or from a cable television network during cable broadcasting is fed to the input of a high-frequency amplifier (UHF), in which the level of the radio signal is amplified to the desired value and preliminary frequency selection is made to select the desired radio channel.

 The intermediate frequency signal from the output of the amplifier is fed to a phase demodulator, in which the signal is demodulated with four-fold phase shift keying. As a result, an interference-protected stream of sound data, data, and control signals appears at the output of the demodulator, which are fed to the input of the channel decoder.

 In the channel decoder, two-stage noise-resistant decoding of the received digital stream is performed to eliminate packet and single digital errors. In the first stage, noise-free decoding of the convolutional code is performed and the original byte order of the sound data is restored. As a result of this processing, the total number of digital errors is significantly reduced and the duration of the packets of digital errors is reduced to one byte. The final correction of digital errors is performed in the second degree of the channel decoder, in which noise-free decoding of the Reed-Solomon code is performed, as a result of which single bit and byte digital errors are eliminated. After correction of digital errors, the signal from the output of the channel encoder is fed to the input of the descrambler, in which the original bit order of the data is restored. The digital stream from the output of the descrambler goes to the input of the demultiplexer (DMUX), in which, in accordance with the received control signal, the required data decoding mode is turned on. So, for example, in the case of using stereo sound mode, the audio data at the output of the demultiplexer is divided into two digital streams, the first of which contains the sound data of the first sound channel, and the second digital stream contains the sound data of the second sound channel.

 The sound data of the first and second sound channels from the two outputs of the demultiplexer are supplied respectively to the first and second MUSICAM decoder.

 In MUSICAM decoders, audio data is converted to analog audio signals that are output to the outputs of decoders 1k and 2k.

 In the case of stereo audio, two analog audio signals from the outputs 1k and 2k of the MUSICAM decoders are simultaneously fed to the receiver's stereo speakers. In the case of bilingual sound accompaniment, the viewer selects one of the sound channels in the language he needs and the selected sound signal (from the output 1k or 2k) is fed to the input of the speaker system.

 For example, when broadcasting a Russian TV program in Ukraine, one sound channel can be used to transmit sound in Ukrainian, and the second channel in Russian.

 In the case of transmission of radio program signals (one stereo or two monophonic), the received signal can be used by viewers in either acoustic playback mode or for recording onto a tape recorder, especially if radio companies will prepare specially selected musical transmission cycles for these purposes. This mode is of particular interest for broadcasting operators of broadcasting and cable broadcasting networks. In this case, the receiving devices are installed at the radio transmitting sound broadcasting stations and at the headends of cable television, which relay the received signals of the broadcasting programs. In this case, the existing radio channels on the air and cable TV broadcasting networks are additionally used for the initial distribution of broadcasting programs.

 The advantage of this method of distribution of radio programs is that the allocation of radio frequencies for new radio channels is not required and equipment already in use is used, which significantly reduces the economic costs of creating such networks for the primary distribution of radio programs.

 In the case of applying the computer data transmission mode, in accordance with the received control signal, the internal circuits are switched in the demultiplexer, as a result of which the received data begins to enter the input of the matching device 2, from the output of which it goes to the input of a personal computer, server, or other similar devices.

 At the first stage of the introduction of digital stereo-sound and bilingual sound accompaniment, the considered receiving device can be produced in the form of a subscriber terminal connected to a standard TV.

 In the future, the corresponding unit will be built directly by manufacturers of TVs directly into their construct.

 The main question that arises when creating a digital sound system for the SECAM DT system is the choice of the frequency interval in the radio spectrum of the SECAM DT system for the placement of a radio-carrying digital signal. There is no such completely free frequency range in the radio spectrum of the SECAM DT system. Therefore, it is necessary to find a compromise solution in which the transient interference from the digital radio carrier was not visually noticeable on the TV screen, and the transient interference from the radio-spectral components of the TV signal did not create audible acoustic interference in the digital sound channels. In addition, it is necessary to ensure the absence of mutual interference between the radio carrier of the digital signal and the frequency-modulated radio carrier of the active sound channel.

 The possibility of reaching such a compromise was not obvious and experimental studies were required to answer this question.

 It is clear that the narrowing of the spectrum of the side bands of the radio-carrying digital signal facilitates the conditions for achieving this compromise. In this regard, the MUSICAM coding system has a noticeable advantage over the NICAM 728 system, since in the MUSICAM system the audio transmission speed and, accordingly, the spectrum width of the radio-carrying digital signal are 3 times lower than in the NICAM 728 system. In addition, to improve compatibility conditions in the system under consideration (as in NICAM 728) the width of the spectrum of the sidebands of the radio-carrying digital signal is reduced by half due to the use of 4-position phase shift keying for sound transmission. As a result, the width of the radio spectrum during digital transmission of two-channel sound accompaniment does not exceed 250 kHz at the level of - 40 dB from the maximum value.

 This made it possible to place the carrier of digital audio signals in the frequency interval between the upper side carrier of the image signal and the lower side frequency-modulated carrier of a standard sound channel, as shown in figure 2, without reducing the frequency band of the radio spectrum of the video channel.

 As a result of research and development, existing mock-ups of the main components of the encoder, modulator, demodulator and decoder systems of SCSS signals have been created. The necessary tests have been carried out, confirming the feasibility of the system,

Claims (3)

 1. A method for generating and transmitting two-channel, including stereo, audio signals, broadcasting, data and control commands in broadcasting and cable broadcasting networks, which enables the transmission of digital audio accompaniment to the consumer with full preservation of the image video signal quality, together with the audio accompaniment to frequency SECAM modulated carrier system, consisting in the fact that they generate sound signals, including stereo, encode the generated signal They multiplex them with the transmitted data signals and control signals and transmit them over the air, receive the transmitted signal on the receiving side, perform demultiplexing with the separation of two coded audio signals and a data signal, decode, decoded audio signals are fed to the receiver stereo system, characterized in that digitally encodes two audio signals through the MUSIC system, transmit command signals, a control signal digitally encoded signals are multiplexed in accordance with the selected data transmission formats, a multiplexed signal is scrambled by modulo addition of two pseudo-random sequences (PSPs) from the PSP generator with a digital signal stream from the multiplexer output, and after scrambling two-stage noise-resistant coding of the scrambled signal is performed, while the first stage produces noise-resistant coding by the Reed-Solomon code to protect against single digital error Iboc, in the second stage - the interleaving of sound data and their convolutional noise-resistant coding to protect against digital packet errors, carry out a four-position phase manipulation of the received noise-free digital stream of the sound signal of data signals, command signal, control signal, while the carrier of the digital sound signal is located in the frequency interval between the upper side carrier of the image signal and the lower side frequency-modulated carrier of the standard channel sound accompaniment, the radio spectrum of the carrier of the modulated signal is transferred to the selected radio frequency channel on the air or cable television broadcasting network, amplified in the power amplifier and transmitted over the air or cable networks, on the receiving side the signal is received at the input of the high frequency amplifier, the spectrum is transferred in the mixer the received radio signal to the intermediate frequency of the receiving device, amplified in the amplifier of the intermediate frequency, carry out frequency selection for selection the signal of the selected radio channel, and the choice of the radio channel can be made by the viewer, carry out phase demodulation with four-position phase manipulation of the signal of the selected radio channel, perform noise-free digital decoding of the received digital stream on the channel decoder, restoring the original data sequence, descramble the signal from the channel decoder, perform demultiplexing digital stream on the demultiplexer, in which, in accordance with Control ignalom switched selected data demultiplexing mode, decoding the demultiplexed signals carried on the first and second decoders music, the decoded audio signals supplied to speaker stereo receiver.  2. A method for generating and transmitting multi-channel audio signals and their translations in several languages, including broadcasting signals, which allows for the transmission of digital audio to the consumer with full preservation of the image video signal quality, together with the sound on a frequency-modulated SECAM carrier system, consisting of the fact that they generate sound signals, including stereo, encode the generated signals, multiplex them with the transmitted and data signals and control signals and transmitted over the air, on the receiving side receive the transmitted signal, perform demultiplexing with the allocation of two encoded audio signals and a data signal, decode, decoded audio signals are fed to the stereo system of the receiving device, characterized in that they carry out digital encoding n sound signals through the MUSIC system, together with n sound signals, transmit data signals, a coma signal nd, the control signal in various combinations, digitally encoded signals are multiplexed in accordance with generally accepted data transmission formats, the multiplexed signal is scrambled by modulo addition of two pseudo-random sequences (PSP) from the PSP generator with the digital signal stream from the multiplexer output, and after scrambling they carry out a two-stage noise-resistant coding of the scrambled signal, while in the first stage, noise-resistant coding is performed by the code Ida-Solomon for protection against single digital errors, in the second stage - interleaving of sound data and convolutional noise-resistant coding for protection against packet digital errors, perform four-position phase manipulation of the received noise-free digital stream of sound signal, data signals, command signal, control signal, at the carrier of the digital sound signal is located in the frequency interval between the upper side carrier of the image signal and the lower side with respect to the modulated carrier of the standard sound channel, the radio spectrum of the carrier of the modulated signal is transferred to the selected radio frequency channel of the broadcasting or cable television broadcasting network in a mixer, amplified in a power amplifier and transmitted via broadcasting or cable networks, on the receiving side the signal is received at the input of a high-frequency amplifier , carry out in the mixer the transfer of the spectrum of the received radio signal to the intermediate frequency of the receiving device, amplify the amplifier in the intermediate part stots, perform the final frequency selection to select the signal of the selected radio channel, and the choice of the radio channel can be made by the viewer, carry out phase demodulation with four-position phase shift keying of the signal of the selected radio channel, perform noise-tolerant digital decoding of the received digital stream on the channel decoder, restoring the original data sequence, perform de-dimming the signal from the channel decoder, carry out digital demultiplexing a stream on a demultiplexer, in which, in accordance with the received control signal, the selected data demultiplexing mode is switched on, the demultiplexed signals are decoded on n MUSICAM decoders, the decoded multichannel audio signals and their translations, including broadcasting signals, are fed to the receiver speaker system.  3. A system for transmitting multichannel audio signals, broadcasting, data and control commands in broadcasting and cable broadcasting networks, which allows for the implementation of digital audio transmission to the consumer with full preservation of the image video signal quality, together with sound on a frequency-modulated carrier SECAM system, containing side of n encoders, the inputs of which are inputs of n sound signals, and the outputs of which are connected to n inputs of the multiplexer, a modulator, a first mixer, a power amplifier, connected to the control input of the first mixer, the output of the first local oscillator is connected, and on the receiving side, a high-frequency amplifier, a second mixer, an intermediate frequency amplifier, a demodulator are connected in series, a local oscillator output, a demultiplexer is connected to the control input of the second mixer , the first and second outputs of which are connected to the inputs of the first and second decoder, characterized in that n encoders are encoders MUSIC, n decoders are with MUSICIANs, on the transmitting side, the first interface block is introduced, the inputs of which are inputs of data and commands, and the output bus of which is connected to the third input of the multiplexer, and the inputs are inputs of a data signal and command signal, the output of the multiplexer is connected to the input of the scrambler, the output of which is connected to the input of the channel encoder, the output of which is connected to the input of the modulator, made in the form of a phase modulator that performs four-position phase manipulation of the carrier, the output of the phase modulator is connected to the first input of the first mixer, the first synchronization block, the output signals of which are connected to the synchronization inputs of all the blocks of the transmitting side, a channel decoder, a descrambler, a second interface block, the input of which is connected to the third output of the demultiplexer, are entered on the receiving side, the demodulator is made in the form of a phase demodulator, the input of which is connected to the output of the intermediate frequency amplifier, the output of the phase demodulator is connected to the input of the channel decoder, the output of which is connected to the input of the descrambler, the output to the second is connected to the input of the demultiplexer, the second synchronization unit, the outputs of which are connected to the synchronization inputs of all blocks of the receiving part.

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