JP3555616B2 - Digital information transmission / reception apparatus and transmission / reception method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a digital information transmission / reception apparatus and a transmission / reception method , and more particularly to a digital information transmission / reception apparatus and a transmission / reception method for bit-compressing, modulating, and transmitting digital information, and receiving the transmitted digital information .
[0002]
[Prior art]
Conventionally, an apparatus for compressing, modulating and transmitting an information signal and receiving the transmitted signal is described in, for example, JP-A-63-28143. This publication describes a technique in which a packet transmission technique is employed to broadcast a program in a fixed time unit in a short time, and the reception side expands the program in real time to reproduce and listen.
[0003]
Further, a commentary article entitled "Audio Signal System of Satellite Television Broadcasting" is published in the Journal of the Institute of Television Engineers of Japan, Vol. 37, No. 5, pp. 366-374 (May 1983). This commentary article describes a television broadcast that compresses an audio signal based on the 14 / 10-bit quasi-instantaneous compression and expansion (5 ranges) rule, transmits the signal in 4-phase DPSK (Differential PHASE SHIFT KEYING), and receives the transmission signal. Is described.
[0004]
[Problems to be solved by the invention]
However, the video information or the relatively insignificant information of the video information and the audio information is reduced, and the modulation is performed so as to reduce the probability of occurrence of an error, and the information is efficiently transmitted within a certain band and transmitted. No description is given of a technique or a receiving apparatus that can receive the information, correct an error generated during transmission, and restore the information without error.
[0005]
An object of the present invention is to provide a digital information transmission / reception device and a transmission / reception method capable of efficiently transmitting bit-compressed video information or audio information and receiving and restoring the transmitted video information or audio information. is there.
[0006]
[Means for Solving the Problems]
To achieve the above object, a digital information transmission / reception device according to the present invention includes a transmission unit for transmitting digital video information and digital audio information, and a reception unit for receiving digital video information and digital audio information. The transmission unit includes a first bit compression unit that performs bit compression on digital video information using a first compression scheme using discrete cosine transform, and a second bit compression unit that performs bit compression on digital audio information using a second compression scheme. Means, common parity signal adding means for adding a parity signal for error detection to the digital video information and digital audio information bit-compressed by the first and second bit compressing means, and the parity signal adding means. Modulation means for phase-modulating digital video information and digital audio information to which a parity signal is added, and transmission means for transmitting the digital video information and digital audio information phase-modulated by the modulation means toward a transmission path. . Further, the receiving section adds a parity signal for error detection to the digital video information bit-compressed by the first compression scheme using the discrete cosine transform and the digital audio information bit-compressed by the second compression scheme. Receiving means for receiving digital information that has been phase-modulated and transmitted to a transmission line, demodulating means for demodulating the digital information received by the receiving means in accordance with the phase modulation, and digitally demodulated by the demodulating means. Error detecting means for detecting error of information using the parity signal; and first bit expansion for bit expanding video information of the digital information error-detected by the error detection means in accordance with the first compression method. Means for expanding the audio information of the digital information detected in error by the error detection means in accordance with the second compression method. It has a door extension means.
[0007]
In order to achieve the above object, a digital information transmission / reception method according to the present invention comprises a first bit compression step of bit-compressing digital video information by a first compression method using discrete cosine transform, A second bit compression step in which bits are compressed by the compression method 2 and a parity signal for error detection added to the digital video information and digital audio information bit-compressed in the first and second bit compression steps. A parity signal adding step, a modulation step of phase-modulating the digital video information and digital audio information to which the parity signal has been added in the parity signal adding step, and a digital video information and digital audio information phase-modulated in the modulation step. And transmitting to a transmission path. Further, a parity signal for error detection is added to the digital video information bit-compressed by the first compression method using the discrete cosine transform and the digital audio information bit-compressed by the second compression method, and phase-modulated. A receiving step of receiving digital information transmitted to the transmission line by a demodulation step; a demodulating step of demodulating the digital information received in the receiving step in accordance with the phase modulation; An error detection step of detecting an error using a signal; a first bit expansion step of bit-expanding video information among digital information error-detected in the error detection step in accordance with the first compression scheme; The audio information of the digital information for which an error has been detected in the error detection step is converted into a sound corresponding to the second compression method. It has a second bit extension step of preparative extension to.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described based on examples with reference to the drawings.
[0009]
FIG. 1 is a block diagram of a digital information receiving and recording / reproducing apparatus including a digital information receiving apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of an embodiment of a digital information transmitting apparatus for transmitting a transmission signal toward FIG.
[0010]
First, the digital information transmitting device of FIG. 2 will be described. In FIG. 2, 1 is a magnetic tape, 2 and 3 are magnetic heads, 4 is a cylinder, 5 is a capstan, 10 is a servo control circuit, 20 is a demodulation circuit, 21 is an error correction circuit, 22 and 23 are compression circuits, 130 Is a control signal generation circuit, 24 is a parity addition circuit, 25 is a modulation circuit, 26 is a transmission circuit, and 27 is a transmission line.
[0011]
The digital video signal and the audio signal recorded on the magnetic tape 1 are reproduced by the magnetic heads 2 and 3 mounted on the cylinder 4 and input to the demodulation circuit 20. The magnetic tape 1 runs on the capstan 5. The running speed of the magnetic tape 1 and the rotation frequency of the cylinder 4 are set to, for example, ten times the normal speed. Therefore, the signal input to the demodulation circuit 20 is time-compressed ten times. For example, if a 120-minute signal is recorded on a magnetic tape, it can be reproduced in 12 minutes.
[0012]
Generally, in the case of recording digital signals on a magnetic recording medium is recorded after being modulated scrambled NRZ, M ² code like. The demodulation circuit 20 performs signal processing for returning the modulated signal to the original digital data, that is, demodulation. The signal demodulated by the demodulation circuit 20 is input to an error correction circuit 21 and detects and corrects erroneous data in a magnetic recording / reproducing process.
[0013]
The video signal and the audio signal are separated and input to the compression circuits 22 and 23, respectively. The video signal is bit-compressed by a discrete cosine transform (DCT). The audio signal is bit-compressed by nonlinear quantization, differential PCM, or the like. As a result, the transmission rate of the total of the video signal and the audio signal is reduced to, for example, 1/20.
[0014]
Output signals from the compression circuits 22 and 23 are input to the parity addition circuit 24. Further, a control signal from the control signal generating circuit 130 is also input to the parity adding circuit 24. Here, the control signal includes at least a control signal for controlling the operation of the printing apparatus as described later. The parity addition circuit 24 adds an error correction parity signal for correcting an error occurring during transmission, and performs signal processing such as serially outputting a video signal and an audio signal according to a transmission format. The output signal of the parity adding circuit 24 is input to the modulation circuit 25. The modulation circuit 25 modulates the serial signal according to the characteristics of the transmission path 27 and the frequency band. In this case, the transmission path 27 is a space. For example, when transmitting by radio waves, the modulation circuit 25 modulates the signal by four-phase phase modulation (QPSK). The modulated signal is input to the transmission circuit 26 and output to the transmission path 27 as a transmission signal. In this way, a signal can be transmitted at a speed ten times that of a normal signal.
[0015]
In the above embodiment, the case where the signal is reproduced from the VTR has been described. However, the signal source is not limited to the VTR, and may be any of a magnetic disk device, an optical disk device, and the like.
[0016]
Next, a digital information receiving and recording / reproducing apparatus including the digital information receiving apparatus according to the embodiment of the present invention shown in FIG. 1 will be described. In FIG. 1, 27 is a transmission line, 30 is a receiving circuit, 31 is a demodulation circuit, 32 is an error correction circuit, 82 is a memory circuit, 80 is a changeover switch, 62 is a decompression circuit, 64 is a D / A conversion circuit, and 70 is An output terminal 131 of the video signal is a control circuit.
[0017]
The transmission signal transmitted from the digital information transmitting apparatus of FIG. 2 to the transmission path 27 is received by the receiving circuit 30. The received signal is input to the demodulation circuit 31. The demodulation circuit 31 corresponds to the modulation circuit 25 shown in FIG. 2 and demodulates the original signal. The demodulated signal is input to an error correction circuit 32, and detects and corrects an error generated in the transmission path 27 based on the error correction parity signal added by the parity addition circuit 24 in FIG. At this time, if the S / N of the transmission system is insufficient and the error cannot be corrected, correction is performed by replacing the signal using the correlation of the signal.
[0018]
The error-corrected video signal output from the error correction circuit 32 is input via the memory circuit 82 to the terminal R selected when the changeover switch 80 records. The memory circuit 82 has a memory capacity of at least one field, and a video signal received at high speed is stored in the memory frame by frame, read out from the memory at a regular speed, and input to the decompression circuit 62.
[0019]
The decompression circuit 62 corresponds to the compression circuit 22 of FIG. 2, and in accordance with the discrete cosine transform (DCT), the compressed video signal is bit-decompressed and restored to the original video signal. The output signal is input to the D / A conversion circuit 64, converted from digital to analog video signal, and output from the output terminal 70.
[0020]
Further, the error-corrected control signal output from the error correction circuit 32 is detected by the control circuit 131, so that the operation of the recording apparatus, for example, the start of recording can be controlled.
[0021]
In FIG. 1, 33 is a parity addition circuit, 34 is a modulation circuit, 40 is a magnetic tape, 41 and 42 are magnetic heads, 43 is a cylinder, 44 is a capstan, 50 is a servo control circuit, 60 is a demodulation circuit, and 61 is Is an error correction circuit, 63 is a decompression circuit, 65 is a D / A conversion circuit, and 71 is an audio signal output terminal.
[0022]
The output signal of the error correction circuit 32 is input to the parity addition circuit 33. The parity adding circuit 33 adds a parity signal for detecting and correcting an error occurring in the process of recording and reproducing. The signal to which the parity is added is input to the modulation circuit 34. The modulation circuit 34 modulates to a code suitable for magnetic recording. For example, the above-mentioned, scrambled NRZ, a ^{M 2} code or the like. The modulated signal is recorded on the magnetic tape 40 by the magnetic heads 41 and 42 mounted on the cylinder 43.
[0023]
At this time, since the signal is time-axis-compressed to 10 times the normal time, the servo control circuit 50 controls the rotation frequency of the cylinder 43 and the traveling speed of the magnetic tape 40 to 10 times the normal time. The rotation control and the control of the capstan 44 are performed. Further, in order to record a predetermined signal at a predetermined position on the magnetic tape 40, synchronization information is detected from the received signal, and the rotation phase of the cylinder 41 is controlled based on the synchronization information.
[0024]
Next, the operation of reproducing the signal recorded in this manner will be described. At the time of reproduction, the running speed of the magnetic tape 40 and the rotation frequency of the cylinder 43 are the same as those for normal reproduction. The reproduced signal is input to the demodulation circuit 60. The demodulation circuit 60 corresponds to the modulation circuit 34, and demodulates and outputs the modulated signal. The demodulated signal is input to an error correction circuit 61, which detects and corrects the error based on a parity signal obtained by adding an error generated in the magnetic recording / reproducing system by a parity adding circuit 33. Further, if there is an error that cannot be corrected, the error is corrected as needed using the correlation of the signal. Also, the video signal and the audio signal are separated and output.
[0025]
The video signal is input to the expansion circuit 62. The decompression circuit 62 corresponds to the compression circuit 22 in FIG. 2, and the compressed video signal is restored to the original video signal by the decompression circuit 62. The output signal is input to the D / A conversion circuit 64, converted from digital to analog video signal, and output from the terminal 70.
[0026]
The audio signal is input to the expansion circuit 63. The expansion circuit 63 corresponds to the compression circuit 23 in FIG. 2, and the compressed audio signal is restored to the original audio signal by the expansion circuit 63. The output signal is input to the D / A conversion circuit 65, converted from digital to analog audio signals, and output from the terminal 71.
[0027]
In the embodiment shown in FIG. 1, the video signal output from the error correction circuit 81 is input to the expansion circuit 62 via the memory circuit 82. However, the output signal of the modulation circuit 34 is demodulated via the memory circuit. The signal may be input to the circuit 60. If the demodulation circuit 60 and the error correction circuit 61 have sufficient operation speed, a memory circuit may be appropriately provided afterward, or if the storage capacities of the error correction circuit 61 and the decompression circuit 62 have some allowance. If it is used, the memory circuit may be omitted.
[0028]
In the embodiment shown in FIGS. 2 and 1, a parity is added to detect or correct an error occurring in the transmission system or the magnetic recording / reproducing system. FIG. 3 shows an example of a method of adding a parity in the case of a magnetic recording / reproducing apparatus using a D2 format, that is, a D2 format VTR. In the D2 format VTR, a signal of one field is divided into a plurality of segments for signal processing, but FIG. 3 shows only one of the segments. In FIG. 3, 90 is a video data group, 91 is an outer code parity group, and 92 is an inner code parity group. First, an outer code parity is added to the data of the video data group 90 arranged in a matrix in the figure in the vertical direction. Thereafter, a recording signal is generated in a form in which the inner code parity is added to the data of the video data group 90 and the outer code parity group 91 arranged in the horizontal direction in the drawing. The generation of the parity is not described in detail here, but is generated according to a generating polynomial G (x).
[0029]
In the embodiments shown in FIG. 2 and FIG. 1, if the parity generation circuits 24 and 33 generate the same parity, most of the error correction circuits 32 and 61 can be shared. That is, since the error correction circuits 32 and 61 are used at the time of recording and at the time of reproduction, respectively, the circuit scale can be reduced by sharing them.
[0030]
FIG. 4 is a block diagram of a digital information receiving and recording / reproducing apparatus including a digital information receiving apparatus according to another embodiment of the present invention. 1 are denoted by the same reference numerals.
[0031]
The transmission signal transmitted from the digital information transmitting apparatus of FIG. 2 to the transmission path 27 is received by the receiving circuit 30. The received signal is input to the demodulation circuit 31. The demodulation circuit 31 corresponds to the modulation circuit 25 in FIG. 2, and is demodulated to an original signal. Here, the demodulated signal is input to the error correction circuit 61 via the terminal R side selected at the time of recording of the changeover switch 132, and the error occurring in the transmission system is detected and corrected. Output separately.
[0032]
The video signal is input to the expansion circuit 62. The decompression circuit 62 corresponds to the compression circuit 22 in FIG. 2, and the compressed video signal is restored to the original video signal by the decompression circuit 62. The output signal is input to the D / A conversion circuit 64, converted from digital to analog video signal, and output from the terminal 70.
[0033]
The audio signal is input to the expansion circuit 63. The expansion circuit 63 corresponds to the compression circuit 23 in FIG. 2, and the compressed audio signal is restored to the original audio signal by the expansion circuit 63. The output signal is input to the D / A conversion circuit 65, converted from digital to analog audio signals, and output from the terminal 71.
[0034]
In the embodiment shown in FIG. 4, the error occurring in the transmission system and the error occurring in the magnetic recording / reproducing system are simultaneously detected and corrected by the error correcting circuit 61 of the reproducing system. Therefore, the signal received by the receiving circuit 30 is demodulated by the demodulation circuit 31 and input to the modulation circuit 34 without error correction or parity addition. Subsequent processing is the same as that of the embodiment shown in FIG. 1. The reproduced signal is demodulated by the demodulation circuit 60 and then input to the error correction circuit 61. As described above, the error occurring in the transmission system and the error occurring in the magnetic recording / reproducing system are simultaneously detected and corrected by the error correction circuit 61 in the error correcting circuit 61 of the reproducing system.
[0035]
In the embodiment shown in FIG. 4, the error correction circuit 32 and the parity addition circuit 33 can be eliminated as compared with the embodiment shown in FIG. 1, and the circuit scale can be reduced.
[0036]
Although not described in the above embodiments, in such a helical scan type magnetic recording / reproducing apparatus, that is, a VTR, an amble signal is added to the head of the signal because a signal is discontinuous when a track is jumped during reproduction. And recorded. Since the addition of the amble signal is also performed in the D2 format VTR, the detailed description is omitted. In order to determine the start position of the signal, a synchronizing signal is appropriately added. However, since a synchronizing signal is also known, for example, in a D2 format VTR, its detailed description is omitted.
[0037]
In the embodiment shown in FIG. 2, the addition of the amble signal may be considered to be performed by the parity adding circuit 24. Alternatively, in order to increase the use efficiency of the transmission path 27, it can be performed on the recording / reproducing apparatus side. In this case, it can be considered that the addition of the amble signal is performed by the parity adding circuit 33 in FIG. In the embodiment shown in FIG. 4, when the amble signal is added on the recording / reproducing apparatus side, it can be considered that it is performed simultaneously by the modulation circuit 34. If the addition of the amble signal is performed on the recording / reproducing device side, the use efficiency of the transmission path 27 can be improved. In addition, the price of the VTR can be reduced, and the effect can be enhanced.
[0038]
As an application example of the present invention, a signal can be transmitted from a digital signal transmitting device to a number of recording / reproducing devices, that is, VTRs, simultaneously and at high speed via a transmission path. At this time, it is difficult to control a large number of VTRs at the same time, and further, it is necessary to perform control such as recording on any VTR and not recording on any VTR. The technology for realizing such control is described below.
[0039]
To this end, a control signal is transmitted when transmitting a digital signal to be recorded. FIG. 5 shows an example of the control signal. In FIG. 5, reference numeral 110 denotes a synchronization signal; 111, an ID signal indicating what kind of control is performed; 112, an address signal indicating which VTR is to be controlled; 113, a VTR designated by the address signal 112; Is a control signal for stopping recording, and 115 is a control signal for stopping recording.
116 is a blank signal, and 120 is a signal to be actually recorded.
[0040]
In response to the synchronization signal 110, an ID signal 111 indicating that an address signal 112 indicating which VTR is to be recorded is transmitted at a predetermined position, and each VTR is set to a standby state. After all the address signals have been transmitted, the recording of the recording signal 120 on the designated VTR can be started by transmitting the ID signal 113. After transmitting the recording signal 120, an ID signal 114 for controlling recording stop is transmitted. The signals 115 and 116 are blank signals, which are signals for making the signal transmission format uniform with other parts and have no meaning.
[0041]
In the embodiment shown in FIG. 2, these control signals are created by the control signal generation circuit 130, and the parity addition circuit 24 adds a parity signal for correcting an error generated during transmission and transmits the control signal.
[0042]
In the apparatus of the embodiment shown in FIG. 1, the signal is received by the reception circuit 30, demodulated by the demodulation circuit 31, and corrected by the error correction circuit 32 during transmission during use. Detects and controls recording and stopping of the recording / reproducing device.
[0043]
In the case of the apparatus of the embodiment shown in FIG. 4, the output signal of the demodulation circuit 31 is input to the error correction circuit 61, and the control signal having the error corrected is input to the control circuit 131 because it is necessary to correct an error occurring during transmission. To enter. The switching circuit 132 is connected to the terminal R for selecting the output signal of the demodulation circuit 31 during recording, and the P side for selecting the output signal of the demodulation circuit 60 is selected for reproduction.
[0044]
Further, as described in the embodiment shown in FIG. 1, by using the switching circuit 132 and the memory circuit, it is possible to monitor a frame-by-frame recording.
[0045]
As described above, by using the present embodiment, a large number of VTRs can be selectively and simultaneously controlled.
[0046]
【The invention's effect】
As described above, according to the present invention, efficiently transmitted bit-compressed video information or video information and audio information are received, and errors that occur during transmission are also corrected, and video information or video information is Audio information can be restored.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a digital information receiving and recording / reproducing apparatus including a digital information receiving apparatus according to an embodiment of the present invention.
FIG. 2 is a configuration diagram of an embodiment of a digital information transmitting device.
FIG. 3 is a diagram showing a conventional parity adding method.
FIG. 4 is a block diagram of a digital information receiving and recording / reproducing apparatus including a digital information receiving apparatus according to another embodiment of the present invention.
FIG. 5 is a diagram of a control signal.
[Explanation of symbols]
Reference numeral 30: receiving circuit 31, demodulation circuit 32, error correction circuit 62, decompression circuit

Claims (10)

A digital information transmission / reception device comprising: a transmission unit that transmits digital video information and digital audio information; and a reception unit that receives digital video information and digital audio information.
The transmitting unit includes:
First bit compression means for bit-compressing digital video information by a first compression method using discrete cosine transform;
Second bit compression means for bit-compressing digital audio information by a second compression method;
Common parity signal adding means for adding a parity signal for error detection to the digital video information and digital audio information bit-compressed by the first and second bit compression means;
Modulating means for phase modulating digital video information and digital audio information to which a parity signal has been added by the parity signal adding means;
Transmitting means for transmitting digital video information and digital audio information phase-modulated by the modulation means toward a transmission path,
The receiving unit,
A parity signal for error detection is added to the digital video information bit-compressed by the first compression method using the discrete cosine transform and the digital audio information bit-compressed by the second compression method, and phase-modulated for transmission. Receiving means for receiving digital information transmitted to the road,
Demodulating means for demodulating the digital information received by the receiving means in accordance with the phase modulation;
Error detection means for detecting an error in the digital information demodulated by the demodulation means using the parity signal,
First bit decompression means for bit-expanding video information of the digital information detected by the error detection means in accordance with the first compression method;
Second bit decompression means for bit-expanding audio information among the digital information detected by the error detection means in accordance with the second compression method;
A digital information transmission / reception device comprising: The digital information transmission / reception device according to claim 1,
First output means for outputting digital video information expanded by the first bit expansion means;
And a second output unit for outputting the digital audio information expanded by the second bit expansion unit. The digital information transmission / reception device according to claim 1,
First D / A conversion means for converting digital video information expanded by the first bit expansion means into analog video information;
Digital information transmission / reception apparatus, comprising: second D / A conversion means for converting digital audio information expanded by the second bit expansion means into analog audio information. The digital information transmission / reception device according to any one of claims 1 to 3,
A digital information transmission / reception device, wherein the first compression method and the second compression method are different from each other. The digital information transmission / reception device according to any one of claims 1 to 3,
The digital information transmission / reception device according to claim 1, wherein the phase modulation is a four-phase modulation. A digital information transmission / reception method for transmitting digital video information and digital audio information and receiving digital video information and digital audio information,
A first bit compression step of bit-compressing digital video information by a first compression scheme using discrete cosine transform;
A second bit compression step of bit-compressing the digital audio information with a second compression scheme;
A common parity signal adding step of adding a parity signal for error detection to the digital video information and digital audio information bit-compressed in the first and second bit compression steps;
A modulating step of phase modulating the digital video information and digital audio information to which the parity signal has been added in the parity signal adding step;
A transmitting step of transmitting the digital video information and digital audio information phase-modulated in the modulation step toward a transmission path,
A parity signal for error detection is added to the digital video information bit-compressed by the first compression method using the discrete cosine transform and the digital audio information bit-compressed by the second compression method, and phase-modulated for transmission. Receiving digital information transmitted to the road,
A demodulating step of demodulating the digital information received in the receiving step in accordance with the phase modulation;
An error detection step of detecting an error in the digital information demodulated in the demodulation step using the parity signal;
A first bit decompression step of bit-expanding video information of the digital information error-detected in the error detection step in accordance with the first compression scheme;
A second bit decompression step of bit decompression of audio information of the digital information error-detected in the error detection step in accordance with the second compression scheme;
A method for transmitting and receiving digital information, comprising: The digital information transmission / reception method according to claim 6,
A first output step of outputting digital video information expanded by the first bit expansion step;
A second output step of outputting digital audio information expanded by the second bit expansion step. The digital information transmission / reception method according to claim 6,
A first D / A conversion step of converting digital video information expanded by the first bit expansion step into analog video information;
And a second D / A conversion step of converting the digital audio information expanded in the second bit expansion step into analog audio information. The digital information transmission / reception method according to any one of claims 6 to 8,
A digital information transmission / reception method, wherein the first compression method and the second compression method are different from each other. The digital information transmission / reception method according to any one of claims 6 to 8,
The digital information transmission / reception method according to claim 1, wherein the phase modulation is a four-phase phase modulation method.

Images