JP2012054747A - Digital transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive system directly collecting log information on the reception side without the necessity of temporary transfer of personnel to an installation site (transmission side) when a transmission section is restored even if a transmission function has a temporarily shut-down failure.SOLUTION: A log state of failure information on the transmission side is accumulated on the transmission side and, even if a transmission function has a temporarily shut-down failure, the state is repeatedly transmitted for a fixed period. The accumulated log information is transmitted when a transmission section is restored and is received on the reception side, so that failure information on transmission side can be acquired.

Description

  The present invention relates to a digital transmission system using an OFDM (Orthogonal Frequency Division Multiplex) modulation scheme or a single QAM (Quadrature Amplitude Modulation) modulation scheme.

Conventionally, in order to image the situation of remote sites such as airports and the situation of dangerous areas, the transmission side equipment equipped with a camera and means for transmission, and the digital that acquires the transmitted video data at the reception side There is a transmission system (see Patent Document 1).
In recent years, digitalization and high-quality image transmission have been realized, but in the case of any abnormality, there are many cases where it takes time to investigate the cause.
For this reason, the digital device is equipped with a log function for leaving the operation state, and becomes effective information for verification in the case of the above-described malfunction.

An example of a digital transmission system will be described with reference to FIG. FIG. 3 shows a configuration example of a conventional digital transmission system including an image transmission / transmission device that wirelessly transmits a video of a predetermined monitoring field captured by a camera and an image transmission / reception device that receives the wirelessly transmitted video. FIG. Reference numeral 120 'denotes an image transmission / transmission apparatus, and 140' denotes an image transmission / reception apparatus. In the image transmission / transmission apparatus 120 ′, 121 is a camera that captures a predetermined monitoring field of view, 122 is an encoder (ENC) that compresses and encodes an output image of the camera 121 in a format such as MPEG2, and 124 is compression-encoded video data. A modulator (MOD) that modulates OFDM, 125 a transmitter (Tx) that converts OFDM-modulated video data into a radio signal, 126 a transmission antenna that outputs the radio signal of the transmitter 125, 127 ′ a camera 121, It is a detector that monitors the operating states of the encoder 122 and the modulator 124. In the image transmission receiver 140 ′, 141 is a receiving antenna that receives a radio signal, 142 is a receiver that extracts a necessary signal from the radio signal received by the antenna 141, and 143 is a demodulator that demodulates the output signal of the receiver 142. Decoders (DEC) 145 are decoders (DEC) that decode the output signal of the demodulator 143. The predetermined monitoring visual field captured by the camera 121 is, for example, a take-off and landing course such as an airport.
In FIG. 3, the detector 127 ′ of the image transmission / transmission apparatus 120 ′ monitors the operation states of the camera 121, the encoder 122, and the modulator 124 in the apparatus at a predetermined sampling period, and a nonvolatile memory such as a semiconductor memory. In addition, the detected operation state is recorded as a log.

JP 2006-287391 A

However, in the above-described conventional digital transmission system, the image transmission receiver 140 ′ side may receive a radio signal in a normal state and output a video signal from the decoder 145, but it is installed remotely. When an abnormality occurred in the image transmission / transmission apparatus, it was necessary to go to the installation site for a non-volatile memory in which a log indicating the operating state was written in order to investigate the cause. Furthermore, ultimately, a situation occurs in which personnel are sent to the installation site to perform repair work. However, personnel cannot easily reach a transmission facility installed in a remote place (for example, a summit or a winter mountain). Similarly, it takes time to get permission or cannot enter or leave frequently in places with dangerous areas or entrance restrictions. For this reason, it took time to acquire the log, and it took time to verify the abnormality and investigate the cause. Also, in places that require permission for admission, such as in airports, it took more time to confirm.
For example, a dedicated line or another STL (Studio to Transmitter Link) is provided for the encoder. However, the system construction cost was expensive.
In view of the above problems, an object of the present invention is to provide a digital transmission system that can quickly acquire a log, and to provide a digital transmission system that can be built at a low cost.

  In order to solve the above-described problems, a digital transmission system according to the present invention is a digital transmission system including an image transmission / transmission device and an image transmission / reception device, wherein the image transmission / transmission device is a camera that captures an image within a monitoring visual field An encoder that compresses and encodes video captured by the camera, a multiplexer that multiplexes output video data of the encoder and abnormality information from a storage unit, and a modulator that modulates an output signal of the multiplexer A transmitter that converts an output signal of the modulator into a radio signal, a transmission antenna, a detector that detects an abnormality in the camera, the encoder, and the modulator, and anomaly information that the detector outputs. The storage unit for outputting to the multiplexer, and the image transmission receiving device receives a necessary signal from a reception antenna and a signal received by the reception antenna. A receiver, a demodulator that demodulates the output signal of the receiver, a separation unit that separates and outputs the abnormal information and the video data from the output signal of the demodulator, and an output of the separation unit An output unit that decodes and outputs the abnormality information; and a decoder that decodes and outputs the video data output from the separation unit.

  The digital transmission system according to the present invention is a digital transmission system comprising an image transmission / transmission device and an image transmission / reception device, wherein the image transmission / transmission device inputs a video signal and compresses the input video. An encoder for converting the output video data of the encoder and the abnormal information from the storage unit, a modulator for modulating the output signal of the multiplexer, and an output signal of the modulator as a radio signal The transmitter for conversion, the transmission antenna, the input video signal, the detector for detecting an abnormality of the encoder and the modulator, and the abnormality information output by the detector are stored and output to the multiplexer. The image transmission receiver includes a reception antenna, a receiver that extracts a necessary signal from signals received by the reception antenna, and an output of the receiver A demodulator for demodulating the signal, a separation unit for separating and outputting the abnormal information and the video data from the output signal of the demodulator, and an output for decoding and outputting the abnormal information output by the separation unit And a decoder that decodes and outputs the video data output from the separation unit.

  The digital transmission system of the present invention is a digital transmission system comprising an image transmission / transmission device and an image transmission / reception device, wherein the image transmission / transmission device inputs a TS signal and outputs the input TS signal. A multiplexer that multiplexes video data and abnormal information from the storage unit, a modulator that modulates the output signal of the multiplexer, a transmitter that converts the output signal of the modulator into a radio signal, and a transmission antenna; A detector for detecting abnormality of the input TS signal and the modulator, and an accumulator for storing abnormality information output by the detector and outputting the information to the multiplexer; The apparatus includes a reception antenna, a receiver that extracts a necessary signal from signals received by the reception antenna, a demodulator that demodulates an output signal of the receiver, and an output signal of the demodulator. A separation unit for separating and outputting information and the video data; an output unit for decoding and outputting the abnormality information output by the separation unit; and decoding and outputting the video data output by the separation unit And a decoder.

  According to the present invention, the log state can be accumulated on the destination device side, and the state can be repeatedly transmitted for a certain time. As a result, even if there is a failure that causes the transmission function to go down temporarily, if the transmission unit returns the accumulated log information, personnel will not be sent to the installation site (transmission side) directly on the reception side. Log information can be collected. Therefore, it is possible to transmit the state on the transmission side with a low cost system with higher accuracy on the reception side. In addition, even if personnel eventually go to the installation site, the parts and tools required for replacement can be estimated to some extent, so that it is possible to carry out repair work easily and quickly without increasing the load. Become.

It is a block diagram which shows the structure of one Example of the digital transmission system of this invention. It is a time chart for demonstrating operation | movement of one Example of the digital transmission system of this invention. It is a block diagram which shows the structural example of the digital transmission system comprised from the conventional image transmission transmitter, and the image transmission receiver which receives the image | video transmitted by radio | wireless.

An embodiment of the present invention will be described below with reference to FIGS. In addition, the following description is for describing one embodiment of the present invention, and does not limit the scope of the present invention. Accordingly, those skilled in the art can employ embodiments in which these elements or all of the elements are replaced with equivalent ones, and these embodiments are also included in the scope of the present invention.
In this document, the components having common functions are denoted by the same reference numerals in the following description of each drawing including FIG. 3 described above, and the description thereof is omitted.

  FIG. 1 is a block diagram showing a configuration of an embodiment of a digital transmission system according to the present invention. In the system of FIG. 1, the image transmission / transmission device 120 ′ is the image transmission / transmission device 120 and the image transmission / reception device 140 ′ is the image transmission / reception device 140 compared to the conventional system of FIG. 3. As a result, in the image transmission / transmission device 120, the detection unit 127 'is changed to the detection unit 127, and the storage unit 128 and the multiplexer 123 are added, compared to the image transmission / transmission device 120'. Further, in the image transmission receiving apparatus 140, a separation unit 144 and an output unit 147 are added as compared with the image transmission receiving apparatus 140 '.

  In the image transmission / transmission device 120 of FIG. 1, the detection unit 127 monitors the operation states of the camera 121, the encoder 122, and the modulator 124 in the device at a predetermined sampling period, and detects an abnormality when it detects an abnormality. The abnormal information is output to the storage unit 128. The storage unit 128 temporarily stores the input abnormality information and outputs it to the multiplexer 123. The multiplexer 123 multiplexes the abnormal information input from the storage unit 128 with the compression-coded video data input from the encoder 122 and outputs the multiplexed video data to the encoder 124. Other operations are the same as those of the conventional image transmission / transmission apparatus 120 '.

1, the demodulator 143 demodulates the output signal of the receiver 142 and outputs the demodulated signal to the separation unit 144. The separation unit 144 separates the input signal into video data and abnormality information, and outputs the separated abnormality information to the output unit 147. The separated video data is output to the decoder 145.
The output unit 147 decodes the input abnormality information and outputs it as log information.
As a result, the abnormality information detected by the detection unit 127 of the image transmission transmission device 120 can be recognized as log information by the image transmission reception device 140 (reception side).
The detection unit 127 may further record the detected operation state as a log in a non-volatile memory such as a semiconductor memory, similarly to the detection unit 127 ′ of FIG.

In the above embodiment, the video data output from the encoder 122 is output as a TS (Transport Stream) signal. The abnormality information is also transmitted in the form of a TS signal. Further, the abnormality information is divided into a plurality of TS signals and transmitted from the image transmission / transmission apparatus 120 to the image transmission / reception apparatus 140.
However, when the transmission line condition deteriorates, the receiving side (image transmission receiving apparatus 140) may not be able to receive the transmitted radio signal.
In addition, there is a situation in which the transmission side (image transmission / transmission apparatus 120) cannot transmit video data due to the occurrence of an abnormality. In this case as well, the reception side cannot receive a radio signal.

In the embodiment of FIG. 1, the signal input to the encoder 122 is not limited to the output signal from the camera 121 and may be a video signal. Further, the video signal may be input to the encoder 121 and also input to the detection unit 127 to detect whether there is an abnormality in the video signal.
Furthermore, the input of the multiplexer 123 is not limited to the output signal of the encoder 122, but may be a TS signal.

  Further, in the digital transmission system of the present invention, an abnormality occurs instantaneously, and after the detection unit 127 detects the abnormality information, the detected information is subjected to a timer process to be extended and maintained for a fixed time. An example of the operation will be described below with reference to FIG. FIG. 2 is a time chart for explaining the operation of the embodiment of the digital transmission system of the present invention. The horizontal axis is a time axis common to FIG. Note that the timer processing of the detection unit 127 is synchronized with, for example, a sampling period, and counts based on a built-in clock frequency in the same manner as the sampling frequency.

FIG. 2A is a diagram showing whether or not an abnormality has occurred in the image transmission / transmission apparatus 120, and the pulse generated at time t0 indicates the occurrence of an abnormality.
FIG. 2B shows a timer output signal indicating that an H (High) level timer output signal is output until time t3 in response to the abnormal pulse of FIG. 2A generated at time t0.
FIG. 2C shows an output signal of the multiplexer 123, and data (LOG1 signal, LOG1 signal) for notifying abnormality information from time t1 when one packet of the TS signal transmitted at the time of abnormality occurring at time t0 ends. LOG2 signal, LOG3 signal...) Are output after a predetermined TS signal (for example, every 3 TS signal packets). Here, the LOG1 signal and the LOG2 signal output from the multiplexer 123 at time t1 and time t2 while the timer output continues are the same abnormality information. The LOG3 signal is a signal indicating that there is no abnormality information to be transmitted.
Note that the contents of the LOG1 signal and the LOG2 signal are at least an abnormality (NG) code and its occurrence time. The LOG3 signal is a code indicating that the abnormality (NG) has disappeared and its time.

FIG. 2D shows the line state of the transmission path. When “good”, the reception side can receive a radio signal, and when “deterioration”, the reception side cannot receive a radio signal.
FIG. 2E shows whether or not a radio signal can be received on the receiving side. “TS”, “LOG2”, and “LOG3” can receive radio signals of respective packets. "Indicates a case where reception may be impossible. FIG. 2E corresponds to “good” and “deteriorated” line conditions. The length of the H-level timer output signal is determined empirically in consideration of the line state deterioration time and the recovery time. That is, even if the abnormal abnormal signal LOG1 generated at time t0 becomes defective in transmission, the same abnormal information can be transmitted again as LOG2 in the same timer output signal, and at that time, the line state is also recovered. The abnormal information can be reliably transmitted to the image transmission receiving device 140.

FIG. 2F shows the signal separation processing of the separation unit 144, which is divided into a “LOG0” period, a “LOG2” period, and a “LOG3” period, and each abnormality information (LOG0 signal, LOG2 signal, And LOG3 signal) are output to the output unit 147, but LOG1 is not output. That is, since the LOG1 signal is not input, the LOG0 signal is not updated until the LOG2 signal is input and separated.
Note that LOG0 in FIG. 2F is abnormality information of an abnormality that occurred immediately before the abnormality that occurred at time t0.

In the situation where the transmission side cannot transmit video data due to the occurrence of an abnormality by performing timer processing on the detected information, extending the fixed time, and inserting the stream multiple times in the multiplexer as in the embodiment of FIG. Even if it exists, the receiving side can receive the abnormality information. That is, even if the radio signal is temporarily interrupted, the accumulated abnormality information is transmitted after the transmission side is restored, and the abnormality information can be received on the reception side.
As described above, since the transmission-side abnormality information is reliably transmitted to the reception side, it is not necessary to send personnel to a remotely installed image transmission transmission device in order to investigate the cause each time it occurs. . Even if it is necessary to visit an image transmission / transmission device installed remotely for repair or adjustment, the contents of the abnormality are known to some extent. Thus, preparation time and repair time can be saved, and repair costs can be reduced.

  120, 120 ′: Image transmission / transmission device, 121: Camera, 122: Encoder (ENC), 123: Multiplexer, 124: Modulator (MOD), 125: Transmitter (Tx), 126: Transmitting antenna, 127, 127 ': Detector, 128: storage unit, 140, 140': image transmission receiver, 141: receiving antenna, 142: receiver, 143: demodulator (DEM), 145: decoder (DEC).

Claims (1)

In a digital transmission system composed of an image transmission transmission device and an image transmission reception device,
The image transmission / transmission device includes a camera that captures an image within a monitoring visual field, an encoder that compresses and encodes video captured by the camera, and a multiplexer that multiplexes output video data of the encoder and abnormal information from a storage unit. A modulator that modulates the output signal of the multiplexer; a transmitter that converts the output signal of the modulator into a radio signal; a transmission antenna; and a detection that detects an abnormality in the camera, the encoder, and the modulator. And storing the abnormal information output by the detector, the storage unit for outputting to the multiplexer,
The image transmission receiver includes: a receiving antenna; a receiver that extracts a necessary signal from a signal received by the receiving antenna; a demodulator that demodulates an output signal of the receiver; and an output signal of the demodulator, Separation unit for separating and outputting the abnormality information and the video data, an output unit for decoding and outputting the abnormality information output by the separation unit, and decoding and outputting the video data output by the separation unit A digital transmission system.

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