JP2002094481A - Digital transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a work of maintaining high quality state by transferring/ transmitting information, so that the presence or absence of reflected waves and a BER value or the like significant for the digital transmission of an OFDM signal or the like can be visualized at other spots. SOLUTION: This digital transmission system is provided with a transfer/ transmission device T equipped with a function for extracting a signal related with the state of electric field strength, presence or absence of reflected wave, and a BER value from a processing part at a reception side, and for integrating the state into a video and a transfer/transmission device R added with a function for extracting the information transmitted so as to be transferred, and for superimposing it is a video valid area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an orthogonal frequency division multiplex (OFDM).
ex) It relates to a digital transmission device using a multi-carrier modulation method such as a modulation method.

[0002]

2. Description of the Related Art In recent years, digital broadcasting has been studied in Europe, the United States, and Japan, and the adoption of an OFDM modulation system as a modulation system is considered to be promising. This O
The FDM modulation method is a type of multi-carrier modulation method and is a combination of a large number of digitally modulated waves. At this time, QPSK (Q
An uadrature Phase Shift Keying (four-phase phase shift keying) method or the like is used, and an OFDM signal that is a synthetic wave can be obtained. Here, when this OFDM signal is expressed by a mathematical formula,
It looks like this: First, assuming that the QPSK signal of each carrier is α _k (t), this can be expressed by equation (1). α _k (t) = _ak (t) × cos (2πkft) + b _k (t) × sin (2πkft) (1) where k indicates a carrier number and a _k (t) , B _k (t)
Is the data of the k-th carrier and takes a value of [-1] or [1]. Next, assuming that the number of carriers is N, the OFDM signal is a combination of N carriers, and if this is β _k (t), this can be expressed by the following equation (2). β _k (t) = Σα _k (t) (where k = 1 to N) (2) By the way, in the OFDM modulation method, a guard interval is added to a signal in order to reduce the influence of multipath. It is common to add. This OFDM signal is composed of the above signal unit, and the signal unit symbol includes, for example, 1024 valid samples and guard interval data 48
Symbol 894 of 1072 samples to which samples are added
Each set is composed of a repetition of a stream unit called a frame consisting of 900 symbols in which six sets of synchronization symbols are added.

FIG. 20 is a block diagram showing a basic configuration of a modulation / demodulation unit in an OFDM transmission apparatus according to the prior art. A transmission line encoding unit 1T, an encoding unit 2T, an IFFT (Inv
erseFast Fourier Transform) section 3
A, a transmission side processing unit 101 including a guard addition unit 3B, a synchronization symbol insertion unit 5, a clock oscillator 6, and a quadrature modulation processing unit 8, and a transmission side Tx having a transmission antenna (not shown)
Receiving antenna and ACG unit 9A, quadrature demodulation processing unit 9B, synchronization detection & correlation unit 4A, FST correction unit 4
B, a FFT (Fast Fourier Transform) unit 3C, a decoding unit 2R, a transmission line decoding unit 1R, and a reception side Rx having a reception side processing unit 203 including a voltage controlled clock oscillator 10. Transmission side Tx
And the receiving side Rx is, for example, a wireless transmission path L using radio waves.
Are tied together. Hereinafter, the modulation / demodulation processing of the OFDM signal will be described with reference to FIG. Transmission side processing unit 101
Din continuously input to the transmission line coding unit 1T of FIG.
Is processed for each frame of, for example, 900 symbols, and within this frame period, every 894 information symbols excluding 6 synchronization symbol periods, for a total of 800 sample periods 1 to 400 and 625 to 1024 Is output as the rate-converted data Dii in the intermittent state. Further, the transmission path encoding unit 1T transmits the frame control pulse FS on the transmission side every 900 symbols which is a frame period.
T is generated and supplied to other blocks as a frame pulse signal indicating the start of a synchronization symbol period. The encoding unit 2T encodes the input data Dii, and outputs data Rf and If mapped to two axes, I axis and Q axis.
The IFFT unit 3A regards these data Rf and If as frequency components and considers the time-axis signal R
(Real number component) and I (imaginary number component).

The guard adding section 3B adds, for example, the waveform of the first 48 samples after 1024 samples, out of the waveforms in the start period of the time-axis signals R and I consisting of 1024 samples, from the time-axis waveform of 1072 samples in total. Output information symbols Rg and Ig. These 48 samples serve as a buffer band when a reflected wave is mixed. The synchronizing symbol insertion unit 5 inserts a synchronizing waveform composed of 6 symbols, which is stored in a memory or the like in advance, into these information symbols Rg and Ig every 894 samples, and converts the frame-structured data Rsg and Isg. create. These data Rs
g and Isg are supplied to the quadrature modulation processing unit 8, where D / A
A converter 81, a quadrature modulator 82, and a local oscillator 83 generate an OFDM modulated wave signal R using a carrier of a frequency Fc.
The signal F is generated, amplified at a high frequency, and transmitted to the transmission line L via a transmission antenna (not shown). As a transmission band, a UHF band or a microwave band is used. Note that a clock CK (frequency 16 MHz) required for processing on the transmission side Tx is supplied from the clock oscillator 6 to each block as a transmission side clock CKd.

[0005] The OFDM modulated wave signal RF transmitted as described above is transmitted via a receiving antenna (not shown) to the receiving side R.
The signal is input to the quadrature demodulation processing unit 9B via the AGC unit 9A, which is a high frequency unit of x, and is multiplied by the quadrature demodulator 91 by the local signal of the frequency Fc ′ supplied from the voltage controlled oscillator 93 to generate the baseband signal. , Are digitized by the A / D converter 92, and the data R'sg and I '
Converted to sg. These data R'sg and I'sg are FF
T (Fast Fourier Transform) section 3C
And generates a gate signal for determining a data period of 1024 samples to be used as an FFT based on the pulse FSTrc, and by excluding 48 samples that are a buffer band, the time-axis waveform signal R'sg, I 'sg is converted into frequency component signals R'f and I'f. Then, these frequency component signals R'f and I'f are identified and decoded by the decoding unit 2R, become data D'o, and output as a continuous signal Dout by the transmission line decoding unit 1R. You. On the other hand, the data R'sg and I'sg are also input to the synchronization detection and correlation unit 4A, where a synchronization symbol group is detected, and a pulse FSTr serving as a frame pulse is extracted. This pulse FSTr becomes a frame control pulse of the receiving side Rx and is supplied to each block of the receiving side Rx. Also,
The synchronization detecting and correlating unit 4A includes a clock CKrc generated from the voltage controlled clock oscillator 10, data R'sg, and I '.
Compare the synchronous components of sg, and calculate the correlation output Sc according to the comparison result.
Is output to the FST correction unit 4B. Then, the control voltage VC is generated by the FST correction unit 4B, thereby controlling the voltage-controlled clock oscillator 10 and the clock CK having the correct cycle.
An rc is generated and supplied to each block on the receiving side.

Next, details of each block shown in FIG. 20 will be described. The transmission path coding unit 1T performs interleave processing, energy spreading processing, error correction code processing, and the like in order to prevent data errors due to various errors that may be mixed during transmission. The encoding unit 2T outputs the signal Dii
Is converted into information on predetermined points on the I and Q axes by using a mapping ROM, and a signal in a period corresponding to an unnecessary carrier is replaced with 0 to generate data Rf and If. The IFFT conversion unit 3A converts the input signals Rf and If into time-axis waveforms R and I having a symbol cycle whose timing is determined by the clock CKd and the pulse FST. Specifically, it can be realized by using PDSP16510 or the like from Pressy. The guard adding unit 3B compares the signals R and I input here by 10
It consists of a delay unit for delaying 24 samples and a switching unit for selecting a delay output only from the 1025th sample to the 1072th sample, and their timing is determined by the clock CK and the pulse FST. All 1 obtained here
The symbol consisting of 072 samples has a time-axis waveform between the first sample and the 48th sample added from the 1025th sample to the 1072th sample, and the information symbols Rg,
Ig. The quadrature modulation processing section 8 uses the D / A converter 81 to perform D / A conversion on the real part signal Rsg and the imaginary part signal Isg.
/ A conversion, and the quadrature modulator 82 modulates the real part signal with the carrier signal of the frequency fc from the oscillator 83, and modulates the imaginary part signal with the carrier of the frequency fc of the oscillator 83. The orthogonal modulation is performed by modulating the signal with a signal shifted by 90 °, and these signals are combined to obtain an OFDM modulated wave signal.

Next, the configuration operation of the receiving side Rx will be described. On the receiving side Rx, the transmitted signal of the frame configuration is input to the AGC unit 9A, where the control signal Sa for correcting the received signal level to an appropriate level is generated and the level is changed. The OFDM frame configuration signal at the appropriate level in the AGC unit 9A is input to the quadrature demodulation processing unit 9B. In this process, contrary to the transmission side Tx, an output demodulated by the quadrature demodulator 91 with the carrier signal of the frequency Fc ′ output from the voltage controlled oscillator 93 is extracted as a real part signal, and the carrier signal is converted by 90 °. The phase-shifted and demodulated output is extracted as an imaginary part signal. Then, the demodulated analog signals of the real part and the imaginary part are converted into digital signals by the A / D converter 92. The synchronization detecting and correlating unit 4A searches for a frame delimiter from the received signals R'sg and I'sg, and
It outputs STrc and outputs a correlation output Sc. Then, the FFT unit 3C delimits the symbol based on the pulse FSTrc, performs OFDM demodulation by performing the Fourier transform as described above, and outputs data R′f and I′f. The decoding unit 2R uses, for example, a ROM table method,
Data R'f and I'f are identified, and data D'o is calculated. The transmission path decoding unit 7 performs deinterleaving processing, energy despreading processing, error correction processing, and the like, and performs continuous digital data Dout, a signal Sb indicating a BER (bit error rate) state, which is an error correction processing state, and The receiving side clock signal CK _RX is output.

Next, FIG. 21 shows an example of a specific configuration of the synchronization detection & correlation unit 4A, which will be described. The time axis signals R'sg and I'sg, which are digital signals subjected to quadrature demodulation, are input to the NULL end detector 4-1 and the SWEEP calculator 4-2. The NULL end detector 4-1 outputs a NULL signal which is in a no-signal state in a synchronization symbol from a frame group of symbols.
, And the approximate position (timing) of the synchronization symbol is detected.
The start time of the EP symbol is estimated, and a SWEEP start instruction pulse ST is output. The SWEEP calculator 4-2 calculates the S
With reference to the WEEP start instruction pulse ST, a waveform existing two symbols after the NULL symbol is estimated as a SWEEP symbol waveform and fetched, and an accurate switching timing of each symbol is searched for. Specifically, SWEEP
For example, a correlation operation is performed between the input OFDM signal and the pattern read from the memory 4-3 using the memory 4-3 storing the symbol pattern, and the correlation output Sc
Is output to the FST correction unit 4B in FIG. The FST correction unit 4B calculates a phase shift from the accurate switching timing of each symbol based on the frame pulse FSTr,
A correction signal VC of the reference clock CKr on the receiving side is output,
The frame phase on the receiving side is matched with the transmission data. The frame counter 4-4 outputs a SWEEP start instruction pulse ST
, The counting of the clock CK is started, and the counted number is set to a value (for example, 107) corresponding to the frame period.
Every time (2 × 900) is reached, the pulse FSTr is output, the count value is returned to 0, and the counting of the clock CK is started again. Therefore, thereafter, the pulse FSTr is output at every fixed count, that is, at each frame start point, and the receiving side uses this pulse FSTr as the start timing of fast Fourier transform, decoding, and inverse rate conversion.

[0009] The correct SWEEP symbol start position can be specified by the SWEEP start instruction pulse ST, and can be taken into the SWEEP calculator 4-2 from the start portion of the SWEEP symbol waveform, so that the phase shift in the SWEEP calculation can be accurately calculated. , It is possible to search for an accurate switching timing of each symbol. That is, based on the correlation output Sc signal output from the SWEEP calculator 4-2, the FST correction unit 4B detects a shift, adjusts the speed of the clock CKrc that is the receiving-side sample rate, and transmits the transmitted synchronization symbol. By performing the phase lock processing, the error in the temporal position of the FFT gate disappears. FIG. 22 shows an example of the correlation output signal Sc in such a case. As is clear from the figure, the correlation output signal Sc in this case has a shape in which a peak due to the main wave and a peak due to the reflected wave exist.

[0010]

By the way, when the digital transmission apparatus as described above is used for moving radio wave transmission such as a marathon relay, a receiving antenna is used as a transmitting antenna of a moving relay car or the like. It is necessary to adjust the direction to receive the strong radio waves in order to aim accurately. Hereinafter, this direction adjustment work is abbreviated and referred to as a tone. Such a marathon relay is called a mobile relay or a mobile transmission. In order to facilitate this adjustment operation, in the conventional device as shown in FIG. 20, the electric field intensity is regarded as the control signal Sa of the AGC unit 9A, and the frequency changes according to the electric field intensity (Sa value). (For example, means (not shown) for expressing electric field strength by sound pitch / low) and an electric field strength level meter. For traditional analog transmission,
In most cases, the transmission quality is better the stronger the electric field. However, in the case of digital transmission, a better transmission state can be obtained in a state where there is no reflected wave and only the main wave exists even if the electric field is slightly weaker than in a state where the electric field is strong and there are many reflected waves mixed. Are overwhelmingly large. In addition, the conventional analog transmission system is largely affected by the reflected wave, and thus has been used only in a state of sight. However, the digital transmission system developed in recent years, especially the OFDM modulation system, is less affected by the reflected wave. As described above, it is actively used for transmission outside the line of sight. However, when the transmission is performed from outside the line of sight, the antenna direction adjuster on the receiving side cannot see the transmitting side. Therefore, in order for the antenna direction adjuster to accurately adjust to the transmitting side that cannot be seen, the electric field strength and the BER (bit error rate) state are detected and displayed on dedicated level meters and the like. And the reproduced image is compared with each other to perform the tone.

Here, in the digital transmission system, in order to convert a received signal into an image, the above-mentioned receiving side processing unit 20 is used.
It is necessary to restore the digital data Dout obtained by OFDM demodulation No. 3 into an image using an MPEG decoder (not shown). As described above, in the digital transmission system, unlike the analog transmission system, it is not easy to visualize the received signal on the receiving antenna side where the antenna direction adjuster exists. In many cases, tone adjustment is performed by relying on a level meter or the like. However, as described above, in the case of digital transmission, a better transmission state is obtained in a state where there is no reflected wave even if the electric field is slightly weaker and a state where only the main wave is present than in a state where the electric field is strong but a large amount of reflected waves are mixed. Because it is overwhelmingly possible to obtain high quality transmission, it is not necessary to grasp the mixed state of reflected waves (ghost state) and to adjust the electric field strength, BER state and reproduced image individually. Cannot be realized.

In a general mobile relay, a receiving relay point is provided on a small hill or the like, and video is transmitted using the above-described OFDM transmission apparatus. Then, the video obtained at the relay stage provided on the small hill or the like is transmitted to a broadcasting station or the like where the studio is located by a micro line of an analog transmission system. Usually, the director (director) in such a transmission system is at the studio, which is the final receiving stage, coordinates the entire transmission relay, and gives instructions to various places. For example,
Broadcasting from multiple mobile transmission images transmitted
An instruction such as selection and determination of a video to be (ON-AIR) is performed. In this case, the transmission state in the digital relay mobile relay transmission changes every moment as described above, but the electric field strength, the BER state, and the mixed state of the reflected wave.
It is not possible to judge whether the transmission state is good or not by just looking at the transmitted video without grasping the (ghost situation).
This is because, in the digital transmission system, the transmitted video is reproduced as a good video until the demodulation becomes as good as possible even if the transmission condition deteriorates, and when demodulation is no longer possible, an abnormality such as a freeze suddenly occurs. Because you do. Accordingly, when the director on the studio side selects and determines an ON-AIR image from a plurality of transmitted mobile body transmission images, the transmission state of each mobile body, that is, the electric field strength, the BER state, and the reflected wave. Situation (ghost situation)
, The appropriate ON-AIR image cannot be selected. For this reason, the selected ON-AIR video may suddenly freeze due to the deterioration of the transmission state, causing a broadcast accident. The present invention eliminates these drawbacks, and stores information such as the electric field strength, BER state, and reflected wave mixing state (ghost state) representing the transmission state in such mobile relay transmission at a point far from the OFDM transmission apparatus. It is an object of the present invention to allow a director or the like to accurately grasp the transmission state by transmitting the image to a studio or the like and displaying the image.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a digital transmission system for relaying at least one stage of a digitized video signal and transmitting the received video signal to a predetermined relay stage. A transmission state in which at least one transmission state information of a reflected wave mixing state, a reception electric field state, and a decoding error state is fetched, converted into a video signal and superimposed on a predetermined period of the video signal, and the superimposed video signal is transmitted. A digital transmission system comprising: video superimposing means; and, at a predetermined receiving stage, means for extracting the superimposed transmission state information from the received superimposed video signal and displaying the extracted transmission state information as a video. .
Further, the acquired transmission state information is converted into a video signal and superimposed outside the valid period of the video signal. Further, the acquired transmission state information is converted into a video signal and is superimposed within a valid period of the video signal. Further, the transmission state information of at least one of the reception electric field state and the decoding error state is a signal in a format expressed by the magnitude of the amplitude level.
Further, the transmission state information of at least one of the reception electric field state and the decoding error state is a signal in a format expressed by the length of a time width pulse. Also, a signal in a format in which any one of the reception electric field state and the decoding error state is a signal represented by the magnitude of the amplitude level, and another transmission state information is represented by the length of the time width pulse. It is what it was. Further, the transmission state information of at least one of the reception electric field state and the decoding error state is a signal in a format represented by the length of the time width pulse, and the time position of the time width pulse is determined from the received superimposed video signal. A means for detecting and detecting the transmission state is additionally provided. As a result, the electric field strength, B, representing the transmission state in such mobile relay transmission,
By transmitting information such as the ER state and the mixed state of the reflected wave (ghost state) to a studio or the like at the final receiving stage, which is a point far away from the OFDM transmission apparatus, and displaying the image,
The director and the like can accurately grasp the transmission state.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an entire block configuration of an embodiment of the present invention, and FIG. 2 shows a schematic diagram of output video signals of respective parts and a video display screen thereof, which will be described in detail. . The transmitting side of a mobile relay vehicle or the like is an MPEG-ENC unit 10
1M and the transmission-side processing unit 101. For example, on the receiving side, which is the first relay stage provided on a small hill or the like, a receiving side processing unit 203, an MPEG-DEC unit 203M, and a transmission state video superimposing unit 7T are provided. Receiving side processing unit 203
Control signal Sa representing the received electric field strength, obtained from
Calculation signal Sc representing the mixing (ghost) state of the reflected wave
And the signal Sb indicating the BER state are connected to the transmission state video superimposing unit 7T. In addition, an FSTrc pulse, which is an operation timing reference of the receiving side processing unit 203, is also connected to the transmission state video superimposing unit 7T. MPEG-ENC unit 203M
2 ((a) in FIG. 2) is input to the transmission state video superimposing unit 7T as a video signal. Here, the video output V
Is not limited to the output of the MPEG-ENC unit 203M, but may be an external input video signal from another video device. The video signal and the audio signal received on the receiving side are sent to a final receiving stage such as a studio directly or via a predetermined number of relay stages. During this time, the data is transmitted by, for example, an analog FPU in a microwave band.

At the transmission destination studio, superimposition information extraction &
A transmission state video converter 7R is provided. The transmission state video superimposing unit 7T receives the signals Sa,
Reflection wave mixing status based on Sb, FSTrc (ghost status)
And the information indicating the transmission state is superimposed on the vertical blanking (VBL) period outside the video effective period of the video signal ((a) in FIG. 2) from the MPEG-ENC unit 203M. . Then, the video signal Vs ((b) in FIG. 2) on which the transmission state information is superimposed is transmitted to the studio using a predetermined video transmission unit. On the studio side, information Sa ′, Sb ′, Sc ′ representing the transmission state superimposed during the VBL period is superimposed by the superimposition information extraction & video conversion unit 7R from the video signal Vs ′ received using the predetermined video reception unit. Extract. Then, information S indicating these extracted transmission states is obtained.
a ', Sb', Sc 'are fetched based on the synchronization signal C.SYNC,
These pieces of information are output as a transmission state imaging signal displayed within a video effective period described later with reference to the synchronization signal C.SYNC. This transmission state imaging signal is displayed on an image display screen as shown in FIG.

FIG. 3 shows a block diagram of one embodiment of the transmission state video superimposing section 7T, which will be described below. The control signal Sa is input to the electric field intensity-image conversion unit 7-1, and the output of the electric field intensity-image conversion unit 7-1 is output to the image integration unit 7-4.
Is input to The signal Sb is input to the BER status-video conversion unit 7-2, and the output of the BER status-video conversion unit 7-2 is input to the video integration unit 7-4. The signals Sc and FSTrc are input to the ghost-to-video converter 7-3. The output of the ghost-to-video conversion unit 7-3 is input to the video integration unit 7-4. The synchronization signal C.SYNC from the video integration unit 7-4 is output from the electric field strength-video conversion unit 7-1 and the BER.
State-Video Converter 7-2, Ghost State-Video Converter 7
-3 synchronous input terminal. In addition, the video integration unit 7-4 outputs a transmission state superimposed video signal described later. The electric field strength / video converter 7-1, BER state / video converter 7-2, and ghost state / video converter 7-3 convert the signals indicating the respective states into video signals according to the input of the synchronization signal C.SYNC. Convert. In the video integration unit 7-4,
These imaged signals are integrated to generate a transmission state superimposed video signal to which a video synchronization signal is added.

FIG. 4 shows a block configuration of an embodiment of the video integration section 7-4, which will be described in detail below. The video signal is supplied to an external video synchronization type synchronization signal generator 7-4-5 and an adder 7-4.
-6 is entered. External video synchronization type synchronization signal generator 7-4
The synchronization signal C.SYNC from -5 is output to the outside. The adder 7-4-6 is provided for each of the visualized signals passed through the gates 7-4-1, 7-4-2, and 7-4-3, and the scale of the time axis and the guard period for the ghost state visualized signal. The signal indicating the range and the video signal are added to create a transmission state superimposed video signal Vs. Note that the superposition position pulse generator 7-4-4 outputs
Defines the position to be superimposed on the video signal. Here, an example of the addition ratio in the adder 7-4-6 is shown below. The input signal is a digital level +5 V electric field intensity imaging signal, a BER state imaging signal, and a ghost state imaging signal, each having a ratio of 0.2, and a time axis scale signal and a guard period range signal being 0. A video signal in which the video portion is an analog signal of about 0.7 V at a ratio of 0.05 is added at a ratio of 1. FIG. 5 shows a schematic waveform of an example of the transmission state superimposed video signal Vs. This is the ghost state imaging signal Ps
c, one line in the VBL period in which the field intensity imaging signals Sa0 to Sa5 and the BER state imaging signals Sb0 to Sb5 are superimposed. Since the ghost state imaging signal is superimposed at the analog level, the ghost state waveform is represented by continuous magnitude of amplitude. The electric field strength level and the BER state are superimposed on a digital value in which each is expressed in binary, assuming the presence or absence of amplitude as digital 0 or 1. That is, the values 0 and 1 of the digitized information are expressed with and without amplitude.

FIG. 6A shows the relationship between the electric field intensity and the image conversion unit 7-
1 shows a block configuration of one embodiment, which will be described below. The control signal Sa indicating the electric field strength is output from the A / D converter 7-1.
-1, for example, a 6-bit digital signal D
Converted to Sa. The signal DSa indicating the electric field strength is converted into, for example, all six signals DSa0 to DSa5 by a decoder (DEC) 7-1-2. Each output of the signals DSa0 to DSa5 is input to six AND gates (AND) 7-1-4.
A total of six outputs of AND7-1-4 are OR gate (OR) 7
Entered in -1-5. The synchronization signal C.SYNC is input to the superposition position pulse generator 7-1-3, where the pulses a0 to a0 of the corresponding superposition position are generated in accordance with the timing of the synchronization signal C.SYNC.
a5 is output. Pulses a0 to a5 are AND7-1-4
And the logical product of the signals DSa0 to DSa5 is obtained. Here, the signal DSa representing the electric field strength is 00
h, that is, if it is 0 in decimal, only the signal Da0 is at the level H, so that the logical product of only the pulse a0 becomes H, and the pulse a0
Is output only at the position corresponding to. Also,
If the signal DSa is 03h, that is, 3 in decimal, DSa0 to DSa3
The logical product becomes H until the signals DSa0 to DSa3 at the positions corresponding to the pulses a0 to a3 are output. And OR7
The logical sum is obtained at -1-5, and the electric field strength imaging signals Sa0 to Sa5
Is output. Here, for example, the pulse a0 is 12H
In the scanning line of the eye, the number of samples corresponds to the position of 512 to 520 samples, the pulse a1 corresponds to the position of the 521 to 529 sample in the scanning line of the 12H, and the pulse a5 corresponds to the position of the 12H to 520 samples. Assuming that the number of samples corresponds to the position of 540 to 548 samples in the scanning line of (5), the electric field strength imaging signals Sa0 to Sa5 at this time are shown in FIG.
As shown in (b), it is superimposed on the VBL period outside the video effective area.

Next, FIG. 7A shows a block configuration of an embodiment of the BER state-video converter 7-2, which will be described below using an example. The signal Sb indicating the BER state is A /
The signal is input to the D converter 7-2-1 and converted into a digital signal DSb of about 3 bits. A signal DSb indicating the BER state
Are output from the decoder (DEC) 7-2-2, for example, by the signals Db0 to Db0.
It is converted into all five signals of Db4. Each output of Db0 to Db4 is input to five AND gates (AND) 7-2-4.
And five outputs of AND7-2-4 are OR gate (O
R) It is input to 7-2-5. The synchronization signal C.SYNC is input to the superposition position pulse generator 7-2-3, and pulses b0 to b4 for superimposing a signal indicating the BER state are output according to the timing of the synchronization signal C.SYNC. . The pulses b0 to b4 are
The signal DSb0 is input to the other terminal of the AND7-2-4 and is input to the other terminal.
ANDed with ~ DSb4. Here, if the signal DSb indicating the BER state is 00h, that is, 0 in decimal, the signal DSb
Since only 0 is at level H, the logical product of only pulse b0 is H
As a result, a signal DSb0 at a position corresponding to the pulse b0 is output. The signal DSb is 03h, that is, 3 in decimal.
Then, the logical product becomes H from DSb0 to DSb3, and the pulse b0
The signals DSb0 to DSb3 at the positions corresponding to .about.b3 are output. The superposition position pulse generator 7-2-3 is, for example, an NTSC
If used, a 910 frequency-divided counter that counts at 14.3 MHz clock and is reset at H cycle,
The count operation is performed by the 1 / 2H clock, and logical processing is performed with a 525 frequency division counter that is reset in the V cycle. As a result, as shown in FIG. 7B, for example, the b4 signal corresponds to the position where the number of samples is 560 to 567 at the 12th scanning line, and the b3 signal is the 12th scanning line at the 12Hth scanning line. , And the number of samples is output corresponding to the position of 568 to 575 samples. As for the b2 signal, the scanning line is at the 12th H, and the number of samples is 576 to 58.
Corresponding to 3 sample positions, the b1 signal is
At the Hth sample, the number of samples corresponds to the position of 584 to 591 samples, and the b0 signal is output corresponding to the position of the twelfth scanning line and the number of samples of 592 to 599 samples. Therefore, the BER state imaging signals Sb0 to Sb4 at this time are superimposed in the VBL period outside the video effective area, as shown in FIG. 7B.

Next, a block configuration of an embodiment of the ghost-to-video converter 7-3 is shown in FIG. 8 and will be described below using an example. The above-described correlation output signal Sc indicating the ghost state is input to the A / D converter 7-3-1 and converted into an 8-bit digital correlation output signal DSc. Then, this signal DSc is input to the FIFO 7-3-2. Further, the pulse FSTrc of the above-mentioned frame period is
It is input to the write reset terminal of 7-3-2. FIF
The O7-3-2 digital correlation output signal D'Sc is input to the D / A converter 7-3-4. The output of the D / A converter 7-3-4 is output as a ghost state imaging signal Psc. Further, the above-mentioned synchronization signal C.SYNC is input to the timing pulse generator 7-3-3. Then, the generator 7-3-3 outputs a read reset signal RRST and a read enable signal RE to the FIFO 7-3-2 according to the synchronization signal C.SYNC. FIG.
Shows the relationship between the signals C. SYNC, RRST, and RE and the ghost state imaging signal Psc, and this operation will be described below. The timing pulse generator 7-3-3 includes, for example,
The reset signal RRST is output at the 128th sample at the 12th H in the video cycle, and the FIFO 7-3-2 prepares to read from the first write content. Also, 12H
The RE signal at the L level is output at the 130th to 400th samples, and the contents (D'Sc) written in the FIFO 7-3-2 are read out in order. The read signal D'Sc is converted into an analog ghost state imaging signal Psc by the D / A converter 7-3-4, and is output during the VBL period of the video period.

Next, a block configuration of an embodiment of the superimposition information extraction & video conversion unit 7R is shown in FIG. 10A, and will be described below using an example. Information sa0 'indicating the transmission state
To sa5 ', sb0' to sb4 ', and Psc' are superimposed information extraction and video conversion units 7R to which the video signal Vs' superimposed during the VBL period is input.
Is a superimposed electric field strength extraction & video converter 7-1V, superimposed BER
State extraction & video converter 7-2V, superimposed ghost state extraction &
It is composed of a video conversion unit 7-3V and a video integration unit 7-4V. The synchronization signal C.SYNC from the video integration unit 7-4V is extracted from the video signal Vs', and the superimposed electric field strength extraction & video conversion unit 7-1V, the superimposition BER state extraction & video conversion unit 7-2V, the superimposition ghost state It is input to the extraction & video conversion unit 7-3V. Output VOsa of superimposed electric field strength extraction & video converter 7-1V, superimposition B
The output VOsb of the ER state extraction & video conversion unit 7-2V and the output VOsc of the superimposed ghost state extraction & video conversion unit 7-3V are input to the video integration unit 7-4V. The superposed electric field strength extraction & video conversion unit 7-1V, the superimposed BER state extraction & video conversion unit 7-2V, the superimposed ghost state extraction & video conversion unit 7-3V are provided with a synchronization signal C.SY.
Each information sa0 'to sa5', sb0 'indicating the transmission state superimposed in the VBL period of the input video signal Vs' with reference to NC.
.. Sb4 ′ and Psc ′ are found, and the information is extracted. Then, as described later, they are converted into respective imaging signals so as to be displayed at predetermined positions within the image valid period. Then, the video integration unit 7-
At 4V, each of these imaging signals is integrated to generate a transmission state imaging signal. FIG. 10B is a schematic diagram showing a case where the transmission state imaging signals (Vosa, Vosb, Vosc) are supplied to a video monitor (not shown) and displayed during the video valid period of the video display screen. As described above, during the image valid period of the image display screen, various transmission state imaging signals (electric field intensity-Vosa, B
Since the ER state-Vosb and the ghost state-Vosc) are displayed, a director or the like located at a studio far from the OFDM transmission apparatus can accurately grasp the transmission state.

FIG. 11A shows a block configuration of an embodiment of the superposed electric field strength extraction and video conversion unit 7-1V, which will be described below. As described above, the analog-state electric field strength information sa0 'to sa5' superimposed on the 12th H of the video signal Vs' is:
The digital signal DSa input to the comparator 7-1V-1
It is converted to 0 'to DSa5'. These signals DSa0 'to DSa5'
Are signals arranged in time series. The signals DSa0 'to DSa
5 'is serial / parallel conversion (S / P) & latch 7-1V
-1a, for example, 6-bit parallel data DSa
[5: 0] is converted to P ′. The output DSa [5: 0] P 'of the S / P & latch 7-1V-1a has been parallelized and sampled and held and is input to the decoder 7-1V-2. The decoder 7-1V-2 outputs a 6-bit DSa [5: 0].
P ′ is converted into, for example, 64 pieces of data DSa63 ′ to DSa0 ′. The outputs DSa63 ′ to DSa0 ′ of the decoder 7-1V-2 are
It is input to 64 AND gates 7-1V-4. AND
A total of 64 outputs of the gate 7-1V-4 are OR gate 7-1V
-5 is entered. The synchronization signal C.SYNC is input to the superposed electric field strength extraction & display position pulse generator 7-1V-3. Superimposed electric field strength extraction & display position pulse generator 7-1V-3
An extraction pulse Psa and display position pulses a63 'to a0' are output according to the timing of the SYNC signal. As the extraction pulse Psa, a total of six pulses are output, for example, between the 512th and the 548th samples at the 12th H outside the video effective period. The display position pulses a0 'to a63' are, for example, scanning lines 200 to 203H,
This is a pulse that becomes level H when the number of samples is 384 samples to 640 samples. That is, the signal a0 'is composed of 384 samples to 3 samples on the scanning lines 200H to 203H.
It is displayed at the position of 87 samples. The a62 'signal is displayed at the positions of 632 samples to 635 samples on the scanning lines 200H to 203H. The a63 'signal is
The scanning lines 200H to 203H are displayed at positions of 637 to 640 samples. This pulse a
0'-a63 'are input to the other terminal of the AND gate 7-1V-4, and the DSa63'-DSa0'
Is ANDed with each output of. Here, FIG.
The extracted pulse Psa and the display position pulses a0 'to a63'
3 schematically shows the positional relationship on the video display screen.

FIG. 12A shows a block configuration of an embodiment of the superimposed BER state extraction & video conversion section 7-2V, which will be described below. As described above, the BER status information Sb0 'to Sb4' of the analog status superimposed on the 12th H of the video signal Vs'.
Is input to the comparator 7-2V-1 and the digital signal
It is converted to DSb0 'to DSb4'. These signals DSb0 'to DSb4'
Is a signal in which all five signals are sequentially arranged in time.
The signals DSb0 'to DSb4' are converted into serial / parallel (S
/ P) & latch 7-2V-2, and are converted into, for example, all five parallel data DSb0 'to DSb4'. Each output of the signals DSb0 'to DSb4' is connected to five AND gates 7-2V
-4 is entered. A total of five outputs of the AND gate 7-2V-4 are input to the OR gate 7-2V-5. Sync signal C.SY
NC is a superposition BER state extraction & display position pulse generator 7-
Input to 2V-3. The generator 7-2V-3 outputs b0 'to b4' pulses, which are display position pulses, during the video valid period according to the timing of the C.SYNC signal. Also, it outputs the extraction pulse PSb ′ at the 12th H outside the video effective period. Here, FIG. 12B schematically shows the positional relationship between the extracted pulse PSb and the display position pulses b0 'to b4' on the video display screen. The superimposed BER state extraction & display position pulse generator 7-2V-3 is 14.3 MHz for NTSC.
A 910 frequency-divided counter that counts with a clock and is reset with an H cycle, and 525 that counts with a 1 / 2H clock and is reset with a V cycle
Performs logical processing with the frequency division counter. As a result, for example,
The b4 'signal has a number of samples of 51 on scanning lines 80H to 96H.
It is displayed at the position of 2 samples to 526 samples. b
The 3 'signal has 528 samples on scanning lines 80H to 96H.
Samples are displayed at positions of ５４542 samples. The b2 'signal is displayed at the positions of 544 to 558 samples on the scanning lines 80H to 96H. The b1 'signal is displayed on the scanning lines 80H to 96H at the positions of 560 to 574 samples. The b0 'signal is displayed on the scanning lines 80H to 96H at the positions of 576 to 590 samples.

FIG. 13A shows a block configuration of an embodiment of the superimposed ghost state extraction & video conversion section 7-3V, which will be described below. As described above, 12 of the video signal Vs'
The ghost state information PSc 'superimposed on the H-th is input to the A / D converter 7-3V-1. The output D'Sc of the A / D converter 7-3V-1 is connected to the write data terminal of the FIFO 7-3V-2. The output D'Sch of the FIFO 7-3V-2 is input to the comparator 7-3V-4. Output L of comparator 7-3V-4
E is input to the gate 7-3V-5. Sync signal C.SYNC
Are connected to a CK regenerator 7-3V-6, an HD extractor 7-3V-7, and a VD extractor 7-3V-8, respectively. CK regenerator 7-
The output CK of 3V-6 is connected to the counter 7-3V-9.
The output WE from the counter 7-3V-9 is FIFO7-3V-2.
WE terminal. The output HD of the HD extractor 7-3V-7 is connected to the counter 7-3V-10. The output CS of the counter 7-3V-10 is connected to the decoder 7-3V-3. The output VD of the VD extractor 7-3V-8 is connected to an H counter 7-3V-11. The output CH of the H counter 7-3V-11 is connected to the decoder 7-3V-3 and the decoder 7-3V-12. The output RRST of the decoder 7-3V-3 is F
Connected to RR terminal of IFO7-3V-2. Similarly, the output RE of the decoder 7-3V-3 is connected to the RE terminal of the FIFO 7-3V-2. The control signal WRST for extracting the ghost state information PSc 'is supplied from the decoder 7-3V-3 to the FIFO 7-
3V-2 write reset terminal WR, WE is FIFO7
Connected to the -3V-2 write control terminal WE. The output Dhh of the decoder 7-3V-12 is connected to the comparator 7-3V-4. The CK reproducer 7-3V-6 reproduces, for example, 14.3 MHz CK based on the input synchronization signal C.SYNC. The HD extractor 7-3V-7 extracts an H cycle component from the synchronization signal C.SYNC, and outputs an H cycle HD signal. Counter 7-3V-1
“0” is reset by the HD signal and outputs a counter signal CS whose value increases every CK cycle.

The VD extractor 7-3V-8 extracts a V cycle component from the synchronization signal C.SYNC, and outputs a V cycle VD signal. The H counter 7-3V-11 is reset by the VD signal and outputs a counter signal CH whose value increases every 1H cycle. The decoder 7-3V-3 outputs the read reset signal RRST which becomes the level L for 1CK period in the 1H period in the period from the mth scanning line to the (m + n) th scanning line based on the input counter signal CS and the counter signal CH. And output FI
The read address of FO7-3V-2 is initialized to 0th. Similarly, a read enable signal RE which becomes level H during the period from the mth scanning line to the (m + n) th scanning line,
By advancing the read address of the FIFO 7-3V-2, the correlation operation signal Sc written in the FIFO 7-3V-2
Is read out. The decoder 7-3V-12
The level la is output to the m-th scanning line from the input counter signal C-H, and thereafter, the level is decreased by i every 1H, and Dhh is set to lb at the m + n-th line. The comparator 7-3V-4 compares D′ sch, which is the correlation operation signal Sc, with Dhh, and sets the output LEh to level H during the period of D′ sch> Dhh.

The state of each signal described above is shown in FIG. 14 and will be further described. The WRST signal is, for example, 12H
100 of the 12th H of the video signal Vs ′ superimposed on the eye
It is output to the sample and initializes FIFO7-3V-2. The WE signal is, for example, 25th from the 128th sample of the 12H of the video signal Vs ′ in which information is superimposed on the 12H.
L is output during the period up to the 6th sample and FIFO7-3V
Write D'Sc to -2. Then, every H cycle, m to m +
The RE signal is output up to the n-th line, and the written contents are sequentially read one by one. The signal D'Sc read according to the H cycle of the video is compared with the value Dhh of the H cycle, and D'Sc <
An LE signal which becomes level H occurs during the period of Dhh. In addition,
In order to prevent the generation of the LE signal during the blanking period, the GI signal which becomes level L during the blanking period is used to forcibly set the level to L during the blanking period. If the level of the Sc signal is high, a ghost state imaging signal having a long H level period is created. As described above, the information such as the electric field strength, the BER state, and the mixed state of the reflected wave (ghost state) indicating the transmission state in the mobile transmission is transmitted to a studio or the like that is far away from the OFDM transmission apparatus. Can be. On the studio side, each piece of information representing the superimposed transmission state is extracted from the received video signal, and each piece of information representing the extracted transmission state is converted into a transmission state video signal within the video valid period. The display allows the director or the like to accurately grasp the transmission state.

Transmission of information indicating the transmission state described above;
In the display method, the transmission state cannot be grasped unless a dedicated receiving device is used on the receiving side. Therefore, in the embodiment described below, in order to be able to grasp the transmission state without using a dedicated receiving device, each information representing the transmission state is expressed in the form of the magnitude of the amplitude level or the length of the time pulse width. Is added to and superimposed on a part of the video signal as a signal represented by. Here, an example of the transmission state superimposed and continuous signal added video signal to which the above-mentioned signal Asa indicating the electric field strength information Sa by the magnitude of the level and the signal Asb indicating the BER state information Sb by the magnitude of the level are added. , FIG. 16 schematically. In other words, there is a video waveform monitor as a device that is always installed or brought into a site such as a mobile relay. By using this waveform monitor and observing only the line where the transmitted superimposed & additional video signal waveform exists using the line selection function,
The transmission state can be visually observed and observed without using a dedicated receiving device (superimposition information extraction & video conversion unit 7R in the above embodiment).

Hereinafter, the transmission state adding unit 7Tsub of the present invention will be described.
FIG. 15 shows a configuration in which the transmission state video superimposing unit 7T shown in FIGS. The video signal serving as a carrier when transmitting each information indicating the transmission state is
The signal is output from the video integration unit 7-4 in the transmission state video superimposing unit 7T, and is input to the i3 terminal of the superimposing unit 7-8 of the transmission state adding unit 7Tsub. A transmission state superimposed continuous signal-added video signal is output from an output terminal O of the superimposing unit 7-8. The electric field intensity information Sa is input to the electric field intensity-level conversion unit 7-6 in the transmission state video superimposing unit 7T and the transmission state adding unit 7Tsub. The BER status information Sb is transmitted to the transmission status video superimposing unit 7.
It is input to the BER state-level conversion section 7-7 in the T and transmission state addition section 7Tsub. The synchronization signal C.SYNC from the transmission state video superimposing unit 7T is input to the electric field strength-level conversion unit 7-6 and the BER state-level conversion unit 7-7 in the transmission state addition unit 7Tsub. Electric field strength-level converter 7
−6 and BER state—output Asa of level conversion section 7-7
And Asb are connected to input terminals i1 and i2 of the superimposing unit 7-8.

Next, the operation of each section will be described. Note that the components having the same reference numerals as those in FIG. The electric field intensity-level converter 7-6 changes an output level (for example, a DC value) according to the state of the input electric field intensity information Sa and generates the electric field intensity information only during a predetermined period based on the C.SYNC signal. The signal Asa is generated as an electric field intensity leveling signal representing the electric field intensity in a level. BER
The state-level conversion unit 7-7 outputs the input BER information S
b, a signal Asb whose output level (for example, a DC value) changes according to the state and which occurs only for a predetermined period based on the C.SYNC signal is generated as a BER state leveling signal indicating the BER state by level. I do. These signals Asa and Asb
Specifically, as shown in FIG. It is added to a part of the non-signal period of the BL period, and the state of the electric field strength information Sa and the BER state information Sb is represented by the level of the level. Specifically, if the level of the signal Asa, that is, the amplitude is large, the electric field strength level is also high. Also,
If the level of the signal Asb, that is, the amplitude is large, BE
The state of R is good. The superimposing unit 7-8 has a terminal i
1, i2 and i3 are added together.

FIG. 17A shows a block configuration of an embodiment of the electric field intensity-level converter 7-6, which will be described below. The electric field strength information Sa is input to the level shifter 7-6-1, and the output Ha of the level shifter 7-6-1 is input to the terminal i of the gate switch (SW) 7-6-2. C. S
The YNC signal is input to the additional position pulse generator 7-6-3. Output GATE-Aa of additional position pulse generator 7-6-3
Is input to the terminal c of SW7-6-2. Next, this operation will be described. The level shifter 7-6-1 outputs a DC voltage Ha higher than the pedestal level of the video signal to be added, at a level corresponding to the electric field strength information Sa. The additional position pulse generator 7-6-3 generates GATE-Aa, which is a control signal for instructing a predetermined period for superimposing Ha on the basis of the C.SYNC signal. SW7-6-2 is the control signal G
According to the state of ATE-Aa, the signal Ha input to the terminal i is
The signal is output from the output terminal O as the electric field intensity level signal Asa. By the operation of each of these parts, the leveling signal Asa
V. as shown in FIG. It is added to a part of the non-signal period of the BL period. In addition, since it is easy to determine whether or not there is a non-signal period as a part outside the superimposition timing of the transmission state video superimposing unit 7T, it may be set to be at that time.

FIG. 18A shows a block configuration for generating a pulse signal whose time width changes in accordance with the BER state information, as one embodiment of the BER state-to-level converter 7-7. explain. The BER status information Sb is input to the level-time converter 7-7-1, and the level-time converter 7-7-1
The output Tb of 7-1 is input to a terminal i of a gate switch (SW) 7-7-2. The synchronization signal C.SYNC is input to the additional position pulse generator 7-7-3,
The output GATE-tb of -7-3 is input to the terminal c of SW7-7-2. Next, this operation will be described in detail.
The level-time converter 7-7-1 outputs a pulse Tb having a DC voltage higher than the pedestal level of the video signal to which the BER status information is added, the pulse width of which changes according to the BER status information Sb. Additional position pulse generator 7-7-3
Generates a GATE-tb which is a control signal indicating a predetermined period for superimposing Tb on the basis of the synchronization signal C.SYNC. GATE-tb has a width corresponding to the maximum time width of the time pulse Tb. The SW 7-7-2 outputs the signal Tb input to the terminal i as the BER state leveling signal Tsb from the output terminal O according to the state of the control signal GATE-Tb. That is, GATE-Tb period width> Tb. By the operation of each of these parts, the BER state leveling signal Tsb becomes V.V. as shown in FIG. It is added to a part of the non-signal period of the BL period. In addition, whether or not there is no signal period is determined by a portion outside the superimposition timing of the transmission state video superimposition unit 7T,
Since it is easy to find out, it is sufficient to set the period. Here, when the BER state is good, the time width of Tsb is long, while when the BER state is bad, the time width of Tsb is short.

In the above embodiment, the configuration shown in FIG. 17 for generating a leveled signal according to the magnitude of the amplitude level is applied to the electric field intensity-level converter 7-6, and the BER state-level converter 7- Although the configuration of FIG. 18 that generates a leveled signal according to the time width of the time pulse is applied to FIG. 7, a combination reverse to this may be used, or a configuration unified to either one may be used. Also, as shown in FIG. 17B, the above-mentioned digitized electric field intensity information Sa and the like are left, and the electric field intensity level signal Asa and the like of the present embodiment are added thereto. Since the electric field strength information is the same, as shown in FIG.
Only sa and the like may be superimposed on the video signal. However, in this case, when the superimposition information is extracted at the transmission destination, it is necessary to recognize that the magnitude of the level and the length of the time width indicate the transmission state and perform the corresponding detection.

The time for detecting the length of this time width-BER
The configuration of the state converter 7-2Vr is shown in FIG. 19A and will be described below. This is the superimposed BER of FIG.
This corresponds to the state extraction & video conversion unit 7-2V.
The video signal Vs' on which the electric field strength information Tsa and the BER status information Tsb are additionally superimposed is input to the falling detector 7-2Vr-1. The output DT-DOWN of the falling detector 7-2Vr-1 is AND
Input to the gate 7-2Vr-3. The synchronization signal C.SYNC is input to the control pulse generator 7-2Vr-5. This output Cu-R
ST is input to the counter 7-2Vr-2. The output LT-Gate of the control pulse generator 7-2Vr-5 is connected to an AND gate 7-2Vr.
Input to the other terminal of r-3. Counter 7-2Vr-
The output Cu-B of No. 2 is input to the latch 7-2Vr-4. AN
The output of the D gate 7-2Vr-3 is input to the LT terminal of the latch 7-2Vr-4.

The operation of each section will be described below. The falling detector 7-2Vr-1 detects a falling portion included in the superimposed video signal Vs'. FIG. 19B shows this state. The falling detector 7-2Vr-1 detects the end point of the pulse in each of the signals Tsa and Tsb in order to perform detection regardless of the type of falling of the input signal. The control pulse generator 7-2Vr-5
According to the C.SYNC signal, a signal LT-Gate that outputs a level H from t4 to t5, which is a period during which the Tsb portion may exist.
And outputs a signal Cu-RST which becomes L only during the same period. AN
The D gate 7-2Vr-3 transmits only the falling pulse only during the period from t4 to t5 to the latch 7-2Vr-4. Counter 7-2Vr-2
Performs a count operation that increases the value with time only during the same period. During other periods, the value remains at 0 because the signal Cu-RST of the level L is continuously input. As a result, the latch 7-2Vr-4 holds the counter value at the moment when the signal Tsb falls. As described above, a value according to the pulse width of the signal Tsb can be extracted.

[0035]

As described above, according to the present invention, transmission states such as an electric field strength state, a BER state, presence / absence of a reflected wave, and a level state can be easily set at another point such as a studio far from the OFDM transmission apparatus. The transmission status of mobile transmission can be easily changed at other points,
And it becomes possible to observe accurately.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the overall configuration of a transmission system according to the present invention.

FIG. 2 is a schematic diagram showing a correspondence between a transmission signal waveform and a video display screen according to the present invention.

FIG. 3 is a block diagram showing an embodiment of a configuration of a transmission state video superposition unit 7T of the present invention.

FIG. 4 is a block diagram showing one embodiment of a configuration of a video integration unit 7-4 of the present invention.

FIG. 5 is a schematic diagram showing a transmission state superimposed video signal waveform of the present invention.

FIG. 6 is a block diagram of an electric field strength-video converter 7-1 of the present invention and a schematic diagram of a corresponding display screen.

FIG. 7 is a block diagram of a BER status-video converter 7-2 and a schematic diagram of a corresponding display screen according to the present invention.

FIG. 8 is a block diagram showing a configuration of a ghost-to-video converter 7-3 according to the present invention.

FIG. 9 is an explanatory diagram of signal timing of each unit of the ghost-video conversion unit 7-3 according to the present invention.

FIG. 10 is a block diagram of a superimposition information extraction & video conversion unit 7R of the present invention and a schematic diagram of a corresponding display screen.

FIG. 11 is a diagram illustrating a superposed electric field strength extraction and video conversion unit 7- according to the present invention.
1V block diagram and schematic diagram of corresponding display screen

FIG. 12 is a diagram illustrating a superimposed BER state extraction & video conversion unit 7 according to the present invention.
-2V block diagram and corresponding display screen

FIG. 13 is a block diagram of a superimposed ghost state extraction & video conversion unit 7-3V of the present invention and a schematic diagram of a corresponding display screen;

FIG. 14 is a time chart illustrating the operation of the superimposed ghost state extraction & video conversion unit 7-3V of the present invention.

FIG. 15 is a block diagram illustrating a configuration of a transmission state video superimposing unit and a transmission state adding unit according to the present invention.

FIG. 16 is a schematic diagram showing a transmission state superimposed video signal waveform of the present invention.

FIG. 17 is a block diagram of an electric field intensity-level conversion unit 7-6 according to the present invention and a schematic diagram of a corresponding display screen;

FIG. 18 is a block diagram and a schematic diagram of a display screen of a BER state-level conversion unit 7-7 according to the present invention.

FIG. 19 is a block diagram and a corresponding time chart of a time-BER state conversion unit 7-2Vr of the present invention.

FIG. 20 is a block diagram showing the overall configuration of a general transmission system.

FIG. 21 is a block diagram showing a configuration of a general synchronization detection and correlation unit 4A.

FIG. 22 is a waveform chart showing an example of a correlation output signal when a reflected wave is mixed.

[Explanation of symbols]

101: transmitting side processing unit, 101M: MPEG-ENC
Section, 203: receiving side processing section, 203M: MPEG-DE
C section, 7T: transmission state video superimposition section, 7Tsub: transmission state addition section, 7R: superimposition information extraction & video conversion section, 7-1: electric field strength-video conversion section, 7-1V: superposition electric field strength extraction & video conversion Section, 7-2: BER state-video conversion section, 7-2
V: superimposed BER state extraction & video conversion unit, 7-2Vr: time-BER state conversion unit, 7-3: ghost state-video conversion unit, 7-3V: superimposed ghost state extraction & video conversion unit, 7
-4: video integration unit, 7-6: electric field strength-level conversion unit,
7-7: BER state-level conversion unit, 7-8: superposition unit.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04N 17/00 H04N 7/08 Z F-term (Reference) 5C061 BB03 CC03 DD01 5C063 AB03 AC01 DA07 DA13 DB02 DB09 5K004 AA05 FE10 FG02 FG04 FH04 FH08 5K022 AA03 AA16 AA26 DD01 DD19 DD23 DD33 DD42 5K047 AA03 AA11 BB01 BB05 CC01 DD01 DD02 EE02 EE04 GG57 HH15 HH17 JJ06 LL06 MM03 MM13 MM26 MM45 MM52MM52

Claims (7)

[Claims] 1. A digital transmission system for transmitting a digitized video signal by relaying at least one stage, wherein at least one of a reflected wave mixing state, a reception electric field state, and a decoding error state is transmitted to a predetermined relay stage from a received video signal. Transmission state information superimposing means for taking in any one of the transmission state information, converting the information into a video signal, superimposing the same in a predetermined period of the video signal, and transmitting the superimposed video signal is provided. A digital transmission system, comprising: means for extracting the superimposed transmission state information from a video signal and displaying the extracted transmission state information as an image. 2. The digital transmission system according to claim 1, wherein the acquired transmission state information is converted into a video signal and superimposed outside the valid period of the video signal. 3. The digital transmission system according to claim 1, wherein the acquired transmission state information is converted into a video signal and is superimposed within a valid period of the video signal. 4. The digital transmission system according to claim 1, wherein at least one of the transmission field information of the reception electric field state and the decoding error state is a signal represented by a magnitude of an amplitude level. Characteristic digital transmission system. 5. The digital transmission system according to claim 1, wherein at least one of the transmission field information of the reception electric field state and the decoding error state is a signal represented by a length of a time width pulse. A digital transmission system characterized by the above. 6. The digital transmission system according to claim 1, wherein any one of the transmission field information of the reception electric field state and the decoding error state is a signal in a format expressed by the magnitude of an amplitude level, and A digital transmission system characterized in that the transmission state information is a signal in a form expressed by the length of a time width pulse. 7. The digital transmission system according to claim 1, wherein at least one of the transmission field information of the reception electric field state and the decoding error state is a signal in a format expressed by the length of a time width pulse. A digital transmission system further comprising means for detecting a time position of the time width pulse from the superimposed video signal and detecting the transmission state.