JP3033702B2 - Transmission device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission apparatus, and more particularly, to the relay of a moving image signal (including sound) such as news to a broadcasting station or the like using a small transmitting station. The present invention relates to a transmission device suitable for use in transmission and the like. 2. Description of the Related Art A so-called ENG (Elecrtic N) that brings a portable VTR to the site to report news by video.
ews gathering) systems are currently being implemented in many broadcasters. Although the introduction of the ENG system has dramatically improved the convenience of news coverage, it is basically impossible to perform real-time broadcasting because recording is assumed. When a real-time relay is required, a microwave line is currently used. However, the use of microwave lines has the drawback that, in relaying from the site of a sudden accident, it takes time and effort to install the lines, and the cost is high. On the other hand, in recent years, the so-called SNG (Satellite News g), which conducts news gathering using communication satellites in the United States.
athering) systems have begun to be introduced and the number of cases where real-time relaying from an in-vehicle earth station to a broadcasting station is increasing. This SNG system uses a very high frequency Ku band (14/12 GHz) to emit video and audio from a site to a communication satellite with a portable transmitter, and transmits the video and audio to a terrestrial station installed in a television station or the like. The relay method to receive at the base,
Live broadcasts can be made immediately from the site. [0006] However, the current SNG
In the system, the FM transmission system which is not always compatible with the communication satellite is used. This FM transmission system is based on an analog signal, and the transmission output at the last stage of the transmitter is as large as 100 W, for example. The diameter is quite large, for example a few meters. Therefore, there is a limit in reducing the size and weight of the transmission station equipment by reducing the transmission output of the transmitter or reducing the size of the parabolic antenna system as long as the FM transmission method is used. [0007] The present invention has been made in view of the above points, and aims to reduce the size and weight of the devices constituting the system.
It is an object to provide a transmission device capable of improving portability and convenience. [0008] In order to solve the above problems, the present invention provides a transmitting apparatus having the following means. That is, a first telephone device for transmitting and receiving telephone voice between a high-efficiency encoding device for encoding a digitized video signal with high efficiency and a second telephone device provided in a receiving device; A multiplexer that multiplexes the efficiency-encoded digital video data, the digitized audio data, and the digitized telephone audio from the first telephone device, and performs convolutional encoding on the multiplexed data. The convolutional encoder to perform and the PS with the convolutionally encoded data
Provided is a transmission device having a PSK modulator that performs K modulation, and a unit that transmits an output signal of the PSK modulator to a satellite. In one embodiment of the present invention, a video signal is converted from an analog signal to a digital signal by an A / D converter 2 on the transmitting side, and the image is encoded by a high-efficiency coding apparatus 3.
To perform high-efficiency coding, that is, to reduce the amount of information, perform convolutional coding for error correction in the convolutional encoder 9, and use the data to convert the carrier wave in the PSK modulator 10 to P
SK modulation is performed and transmitted to the receiving side via a satellite. On the receiving side, the received signal is PSK-demodulated by the PSK demodulator 24 and error-corrected by Viterbi decoding by the Viterbi decoder 25, that is, the maximum likelihood decoding of the convolutional code is performed by the Viterbi algorithm, and the data is obtained. The high-efficiency image decoding device 27 obtains the original data from the data whose information amount is reduced, that is, restores the digitized original video signal. As a result, the power required for transmission can be reduced to a fraction of that in the FM transmission system. Hereinafter, this embodiment will be described in detail with reference to FIGS. FIG. 1 shows an example of a circuit configuration of a relay transmitting station. In FIG. 1, reference numeral 1 denotes an input terminal to which a video signal is applied. The video signal is supplied to the A / D converter 2, where it is converted from an analog signal to a digital signal. The digitized video signal is supplied to a high-efficiency image coding apparatus 3, where high-efficiency coding, that is, reduction of the amount of information (band compression) is performed. The method of reducing the amount of information is not specified here, but the input coded (A / D) by, for example, CCEIR Rec (Recommendation) 601 by an appropriate method is 216 Mbps. For example, it is possible to reduce the amount of information to 12 Mbps and to reduce image quality deterioration. The video signal from the encoding device 3 whose information amount has been reduced is supplied to the multiplexer 4. Reference numeral 5 denotes an input terminal to which an audio signal is applied. The audio signal from this input terminal 5 is supplied to an A / D converter 6, where it is converted from an analog signal to a digital signal, and is supplied to a multiplexer 4. Supplied. Reference numeral 7 denotes a telephone. An audio signal from the telephone 7 is supplied to a telephone codec (Coder & Decoder) 8, where it is A / D converted into a digital signal of, for example, 64 Kbps and supplied to the multiplexer 4. The signals from the encoding device 3, the A / D converter 6, and the telephone codec supplied to the multiplexer 4 are multiplexed and serialized into a data format as shown in FIG. That is, in FIG. 3, a synchronizing signal is inserted at the beginning of the format, and thereafter, audio data from the input terminal 5, audio and other control data from the telephone 7, and video data from the input terminal 1 are respectively transmitted. Are arranged. The data serialized by the multiplexer 4 is supplied to a convolutional coder 9, where convolutional coding for error correction is performed. Here, the coding rate of the convolutional coding is determined by the balance of the entire system, and is not particularly specified. The coded data is supplied to a PSK modulator 10 where the data has a predetermined frequency, for example, 1
The 40 MHz carrier is PSK modulated. PSK modulator 1
The output signal of 0 is supplied to the up-converter 11, and is up-converted in accordance with the frequency of a repeater of a communication satellite (not shown) used here, for example, 14 GHz. The up-converted signal is, for example, 10
W is supplied to a high power amplifier (W) 12 for amplification, and is supplied to a parabolic antenna 14 having a small diameter, for example, about 1.2 to 1.8 m, through a duplexer 13, and then to a communication satellite. Sent to. When voice information from the telephone set generated by the receiving station for the office, ie, the fixed station as shown in FIG. 2 is received by the parabolic antenna 14, the voice information is reduced through the duplexer 13. Noise Amplifier (Low Noise Amplifier) 15
And amplified. The output signal of the low-noise amplifier 15 is supplied to a down-converter 16, where the next-stage PS
The signal is down-converted to a predetermined frequency, for example, 140 MHz in accordance with the intermediate frequency of the K demodulator 17. The output signal from the down-converter 16 is supplied to a PSK demodulator 17, where it is demodulated with PSK and data is demodulated. This PSK demodulator 17 may be an FSK demodulator. The PSK demodulated data is supplied to a Viterbi decoder 1
8 for error correction by Viterbi decoding. That is, the maximum likelihood decoding of the convolutional code is performed by the Viterbi algorithm. The decoded data is supplied to the telephone codec 8, where it is D / A converted and supplied to the telephone 7. As a result, the telephone voice transmitted from the fixed station is received by the telephone of the relay transmitting station via the communication satellite. FIG. 2 shows the circuit configuration of a receiving station for a station, that is, a fixed station. In FIG. 2, reference numeral 20 denotes a parabolic antenna having a medium diameter, for example, about 3 to 5 m. As described above, the transmission information of 14 GHz emitted from the transmitting station of FIG. 1 to the communication satellite is converted into a predetermined frequency, for example, 12 GHz by the communication satellite, and received by the parabolic antenna 20. Information from the parabolic antenna 20 is supplied to a low-noise amplifier 22 via a duplexer 21 and amplified. The output signal of the low noise amplifier 22 is the down converter 2
3, and is down-converted to a predetermined frequency, for example, 140 MHz in accordance with the intermediate frequency of the next-stage PSK demodulator 24. The output signal from the down converter 23 is supplied to a PSK demodulator 24, where it is PSK demodulated, and data is demodulated. The PSK demodulated data is transmitted to the Viterbi decoder 2
5 for error correction by Viterbi decoding. That is, the maximum likelihood decoding of the convolutional code is performed by the Viterbi algorithm. The decoded data is supplied to a demultiplexer 26.
The video signal and the audio signal are divided, and if a telephone audio signal is also included, this is also divided. The split video signal is supplied to an image high-efficiency decoding device 27, where high-efficiency decoding is performed.
It is converted to a 16 Mbps digital signal. This digital signal is converted into an analog signal by a D / A converter 28, and an original video signal is obtained at an output terminal 29. The audio signal split by the demultiplexer 26 is converted from a digital signal into an analog signal by a D / A converter 30 and is taken out to an output terminal 31 as an original audio signal. The telephone voice signal split by the demultiplexer 26 is D / A converted by the telephone codec 32 and supplied to the telephone 33 as an analog signal. The audio signal from the telephone 33 is A / D-converted by the telephone codec 32, for example, to 64 Kbps.
And supplied to a convolutional encoder 34, where convolutional encoding for error correction is performed. Here, the coding rate of the convolutional coding is determined by the balance of the entire system, and is not particularly specified. The convolutionally encoded data is supplied to a PSK modulator 35, and the data is subjected to a predetermined frequency such as 1
The 40 MHz carrier is PSK modulated. This PS
K modulator 35 may be an FSK modulator. The output signal of the PSK modulator 35 is supplied to an up-converter 36, and is up-converted in accordance with the frequency of a repeater of a communication satellite (not shown) used, for example, 14 GHz. The up-converted signal is supplied to the high power amplifier 37, amplified, supplied to the parabolic antenna 20 via the duplexer 21, and transmitted to the communication satellite. Thereafter, as described above, the call is received by the relay transmitting station of FIG. 1 via the telephone line for communication. FIG. 4 shows an example of the high-efficiency image coding apparatus 3. In FIG. 4, reference numeral 41 denotes an input terminal to which a digitized video signal is supplied. It is recommended that CCIR Rec 601 follow the component coding rules. Therefore, the input terminal 41 has a component-encoded video signal such as a luminance signal (Y) having a sampling frequency of 13.5 MHz and a quantization number of 8 bits and a color difference of a sampling frequency of 6.75 MHz and a quantization number of 8 bits. A signal (RY, BY) is applied. The video signal from the input terminal 41 is supplied to a motion detection circuit 42 and a sub-sampling circuit 43. Note that only the luminance signal may be supplied to the motion detection circuit 42. The motion detection circuit 42 detects (evaluates) the amount of motion between the previous screen (previous frame) and the current screen (current frame). Although various detection methods are conceivable, for example, a frame memory is provided, and a difference between the previous screen and the current screen is calculated for each sample and accumulated, thereby detecting the amount of motion. The sub-sampling circuit 43 performs thinning-out (sub-sampling) in the format described below because of the difference in human visual characteristics between the luminance component and the color component and the balance with a later-described interpolation circuit. First, the sub-sampling of the luminance signal Y will be described. The sub-sampling pattern of the luminance signal is as shown in FIG. In FIG. 5, the vertical axis represents the number of scanning lines, the first field (for example, the K-th field, the K + 2-th field, etc. represented by a solid line) is 263 lines,
The fifth field (for example, the (K + 1) th field, the (K + 3) th field, etc. represented by a broken line) is 262 lines, but here, only n ‥‥‥ n + 3 lines are representatively shown.
The horizontal axis represents the number of samples (pixels), which is 858 per line (1H).
Only the sample of ‥ m + 3 is shown. The feature of this pattern is that in all fields, the samples to be transmitted (samples to be interpolated later) and the samples to be transmitted have the same positional relationship (see FIG. 6). The change of the subsampling pattern is completed in four fields, that is, two frames, and this is repeated. The subsampling of this pattern reduces the amount of information to half. Here, when constructing the interpolation filter, it means that all the non-transmitted samples can be interpolated with the same configuration, or all information before sub-sampling in two frames for a still picture is transmitted, This means that the resolution may be increased to the state before sub-sampling depending on the interpolation method. Next, the sub-sampling of the color difference signals (BY, RY) will be described. The sampling pattern of the color difference signal is as shown in FIG. In FIG. 7, the vertical axis represents the number of scanning lines. The first field (for example, the Kth field, K + 2, K + 4 field, K + 6 field, etc. represented by a solid line) has 263 lines, and the second field (for example, represented by a broken line). The K + 1 field,
The (K + 3 field, the K + 5 field, the K + 7 field, etc.) are 262 lines.
Only the # n + 5 line is shown. The abscissa represents the number of samples (pixels), which is 429 per line (1H). Here, only samples of m ‥‥‥ m + 4 are representatively shown. The feature of this pattern is that, similarly to the luminance signal, the lines to be transmitted in all the fields have the same relative positional relationship between the non-transmitted samples (samples to be interpolated later) and the transmitted samples (see FIG. 4). ). In all the fields, the color difference signals (BY, R
-Y) is non-transmission alternately for each line. The subsampling pattern changes for each field, and the change completes and covers all sample positions in eight fields (four frames). By sampling this pattern, the information amount of both signals is reduced to 1/4. Here, and means that all the sample interpolation without transmission is possible with the same configuration when configuring the interpolation filter, or that all information before sub-sampling 4 frames for a still picture is transmitted, and This means that the resolution may be increased up to the state before sampling depending on the method. The motion detection circuit 4 thus detected
The motion amount between the previous screen and the current screen from Step 2 and the sub-sampled (decimated) sample from the sub-sampling circuit 43 are supplied to the predictive coding circuit 44, where the predictive coding taking the motion amount into consideration is performed. That is, the motion compensation prediction coding is performed, and the variable length coding circuit 45 performs variable length coding on the prediction residual signal and outputs the result to the output terminal 46. Therefore, greatly reduced information can be obtained at the output terminal 46. For example, when the information applied to the input terminal 42 is 2
Assuming 16 Mbps, the output terminal 46 has 12 Mbps
Information is obtained. Then, the evaluation value of the motion amount and the variable-length coded data are transmitted from the output terminal 46 to the multiplexer 4 (FIG. 1). FIG. 8 shows an example of the image efficient decoding device 27. In FIG. 8, reference numeral 47 denotes data relating to the video signal decoded by the Viterbi decoder 25 (FIG. 2). Is an input terminal supplied via the demultiplexer 26, and this input terminal 47
Is supplied to a variable-length decoding circuit 48, where the variable-length code is decoded, and a predictive decoding circuit 49 performs predictive decoding, that is, motion-compensated predictive decoding using the motion amount evaluation value, and sends the result to an interpolation circuit 50. Supply. The interpolation circuit 50 interpolates the sub-sampled (thinned out) samples using the motion amount evaluation value.
That is, the interpolation circuit 50 weights and adds both the in-field interpolated value generated by the sub-sampled sample and the sample value at the corresponding sample position transmitted in the past in accordance with the amount of motion, and outputs the result to the output terminal 51.
Output to FIG. 9 shows an example of a specific circuit configuration of the interpolation circuit 50. In practice, such a circuit is provided for each of the luminance signal Y, the color difference signals BY and RY. In FIG. 9, reference numeral 52 denotes an input terminal to which a motion amount from the motion detection circuit 42 (FIG. 4) is supplied, and 53 denotes a sub-sampling circuit 4.
3 (FIG. 4) is the input terminal to which the sub-sampled sample is supplied. The sub-sampled sample from the input terminal 53 is supplied to the intra-field interpolation filter 5.
4 and the frame memory 55. The intra-field interpolation filter 54 determines a sample value at a sample position not transmitted from a sample transmitted within the field, that is, obtains an intra-field interpolation value. The frame memory 55 updates only the transmitted sample and outputs a sample of two fields (for a luminance signal) or four fields (for a color difference signal) corresponding to the sample position output by the interpolation filter 54. The interpolation filter 54 and the frame memory 55
Are supplied to multipliers 56 and 57, and input terminals 5
2 is weighted according to the amount of movement. That is, the multiplier 56 has a coefficient K, and the multiplier 57 has a coefficient (1−K). For example, if the motion amount is the same as the coefficient K (0 ≦ K ≦ 1), the larger the K, the larger the interpolation filter 54. , The weight of the output of the frame memory 55, that is, the weight of the sample actually transmitted, increases if K is small. For example, when a completely still screen continues for four or more frames, the value of K becomes 0, and as a result, the multiplier 56
Becomes 0, the output of the multiplier 57 becomes equivalent to the output of the frame memory 55, and these are added by the adder 58 and output to the output terminal 59. As a result, the output terminal 59
Only the output of the frame memory 55 is obtained. At this time, the same resolution as that obtained when no sub-sampling is performed is obtained. As described above, in this embodiment, by digitizing, the information compression technology in the digital stage can be applied, convolutional coding and Viterbi decoding can be applied, and digital modulation / demodulation technology suitable for a communication satellite can be applied. With these combinations, the power required for transmission can be reduced to a fraction of the power required for the FM transmission system. Accordingly, it is possible to reduce the size of the antenna and the size of the power generator, thereby improving the portability of the relay transmitting / receiving station. The improvement in portability leads to a reduction in control in system operation, so that the convenience of the system is also improved. As described above, according to the present invention, a video signal is digitized on the transmission side, and high-efficiency coding is performed by motion-compensated predictive coding and variable-length coding, that is, a large amount of information is reduced. , Perform convolutional coding, perform PSK modulation,
Transmitted to the receiving side via satellite, PSK demodulated on the receiving side, Viterbi decoding is performed, high-efficiency decoding is performed by variable length decoding and motion compensation prediction decoding, and the digitized video signal is restored. As a result, the required power can be reduced to a fraction of the power required by the conventional FM transmission system, making it possible to reduce the size and weight of the devices that make up the system, and to improve the portability and convenience of the devices. it can. Furthermore, according to the present invention, when performing highly efficient coding by motion compensation prediction coding and variable length coding to greatly reduce the amount of information and transmitting data via satellite, Although weaker, the convolutional coding enables strong error correction, so that the data can be transmitted with a reduced data error rate while significantly compressing the bandwidth of the data. This effect is obtained for the first time by the transmitting device of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit configuration diagram showing one embodiment of the present invention. FIG. 2 is a circuit configuration diagram showing an embodiment of the present invention. FIG. 3 is a diagram showing a data format for explaining the operation of the present invention. FIG. 4 is a circuit configuration diagram showing an example of a part of a main part of the present invention. FIG. 5 is a diagram for explaining the operation of FIG. 4; FIG. 6 is a diagram for explaining the operation of FIG. 4; FIG. 7 is a diagram for explaining the operation of FIG. 4; FIG. 8 is a circuit diagram showing an example of another main part of the present invention. FIG. 9 is a configuration diagram illustrating an example of a specific circuit of FIG. 8; [Description of Code] 2 A / D converter, 3 image high efficiency coding device, 9 convolutional coder, 10PSK modulator, 14, 20 parabolic antenna, 24 PSK demodulator, 25 Viterbi decoder, 27 image high efficiency Decoding device, 28 D / A converter

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Naohisa Kitasato               6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo So               Knee Co., Ltd. (72) Inventor Yuichi Kojima               6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo So               Knee Co., Ltd.                (56) References JP-A-60-79887 (JP, A)                 JP-A-56-17534 (JP, A)                 JP-A-62-23583 (JP, A)                 JP-A-60-167533 (JP, A)                 "Revision Satellite Communication Technology", Kenichi Miya               Supervision, February 15, 1985, Electronics Corporation               Published by The Telecommunication Society

Claims (1)

(57) [Claims] A high-efficiency encoding device for encoding a digitized video signal with high efficiency; a first telephone device for transmitting and receiving telephone voice between a second telephone device provided in the receiving device; A multiplexer for multiplexing the digitized digital video data, the digitized audio data, and the digitized telephone audio from the first telephone device, and performing convolutional encoding on the multiplexed data. Convolutional encoder and PS for performing PSK modulation on convolutionally encoded data
A transmission device comprising: a K modulator; and a means for transmitting an output signal of the PSK modulator to a satellite.