JPH02285827A - Program transmission system for video and audio signal - Google Patents

Abstract

PURPOSE:To eliminate the interruption of a program signal and the discontinuity of a signal at program signal changeover by comparing and checking signals of 2 systems for preceding and succeeding reproduction in a couple of digital tape recorders and selecting a signal with better quality automatically. CONSTITUTION:A magnetic tape for program transmission with an entirely same program signal recorded digitally thereon is set to a main DTR digital tape recorder 11 and a sub DTR 12. Each tape is run entirely synchronously with each other timewise. A signal reproduced by a preceding reproduction head 21 is stored tentatively in a memory MEM 31. A signal reproduced by a succeeding head 22 is inputted to a DCHK circuit 32, in which the signal is compared sequentially with the preceding reproduction signal at the same time from the MEM 31 and when the result of comparison is dissident, a flag output of the DCHK circuit 32 is set to a high level. An FCHK circuit 13 detects it, a control signal output is sent to an SW circuit 14, which selects a Dout based on the control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a system for transmitting video and audio programs for television and radio broadcasting, and more particularly to a system for transmitting program program signals using a tape recorder for transmission.

Conventional technology In recent years, various improvements have been made in video and audio program transmission systems to realize unmanned and automated system operation, and now a parallel operation system using two transmission tape recorders is widely used ( It has been adopted.

A conventional video/audio program transmission system using a parallel operation method will be described below.

Figure 3 shows the main configuration of a program signal switching boot in a conventional program transmission system.
2 is a sub-ATR for sending out, and 3 and 4 are continuity check (hereinafter abbreviated as I) signal detection circuits from each ATR. 5 is a signal comparison circuit; 6 is a program signal switching relay that operates in conjunction with the output from the I signal comparison circuit 5;

The operation of the program transmission system configured as described above will be explained below.

First, in these ATRs, the program program signal, I signal, and run start number stop (hereinafter abbreviated as Q) signal are recorded on the same tape, so when the program program signal recording tape is played back, , L and Q signals are also played back at the same time, and in particular, by detecting the presence or absence of the I signal, it is possible to immediately confirm the continuity of the program program signals at the same time.

Next, the procedure for transmitting the program program signal will be explained.

The main and sub ATRs 1 and 2 are operated in time synchronization based on the Q signal that controls the running from the stage of running in preparation for playing back a tape for broadcasting a program. therefore,
The reproduction signal of the main ATR 1 and the reproduction signal of the sub-ATR 2 are exactly the same in terms of time, and the program signal switching relay 6 normally selects the reproduction signal on the main ATRI side.

Now, if for some reason the level of the reproduction signal of the main ATR 1 drops or stops, the level of the I signal detected by the signal detection circuit 3 will also change, so the signal comparison circuit 5 will An abnormal playback operation is detected. Based on this, the relay 6 is activated, the program signal is switched to the reproduction signal of the sub-ATR 2, and the transmission of the program program signal is continued. During this time, the main ATR 1 can be repaired, and the relay 6 can be manually or automatically switched to the main ATR 1 side again if necessary.

As described above, in the conventional program transmission system, the program signal is switched using the change in the signal.

Problems to be Solved by the Invention However, in the above-mentioned conventional program transmission system based on I signal detection, level fluctuations are unavoidable because this signal itself is an analog signal, and a predetermined threshold value and a It was necessary to set the detection time. Therefore, the determination takes time on the order of seconds, and during this time the program program signal is interrupted, and there is a problem in that the clock sound is loud when reconnection is made.

The present invention solves the above-mentioned conventional problems, and eliminates interruptions in the program program signal, eliminates signal discontinuity when switching the program program signal, and improves the quality of the video of the program program signal. - The purpose is to provide an audio program transmission system.

Means for Solving the Problems The present invention provides at least one pair of magnetic recording/reproducing heads for performing preceding reproduction and subsequent reproduction, a signal processing block for reproduced signals, a memory dedicated to the preceding reproduced signal, and a preceding reproduction head. and a signal inspection circuit for comparing and inspecting each of the signals reproduced later, and operating these two units in temporal synchronization based on time code information, and each of the digital tape recorders. A flag comparison circuit that compares the flag output based on the pass/fail inspection results from the signal inspection circuit of the recorder, and a flag comparison circuit that operates in conjunction with this flag comparison circuit to compare the quality of the program program signals reproduced from the two digital tape recorders. The present invention is characterized by comprising a signal switching circuit that automatically selects a better signal.

Operation In the present invention, the reproduction signal of one of the main DTRs (DTR) is normally selected and output to the outside due to the above-described configuration.

Here, if an abnormality or quality deterioration occurs in the preceding reproduction or subsequent reproduction signal of the main DTR and an error occurs in the decoded signal in the signal processing block, the signal inspection circuit in the main DTR detects the mismatch in the signals. Outputs a high-level flag representing the Therefore, the flag from the main DTR and the flag from the sub DTR are compared by the flag comparison circuit, and the flag from the other DTR is compared.
The program signal from the TR can be sent out by the signal switching circuit.

In this way, in the event of an abnormality or quality deterioration of the reproduction signal in the main DTR, the reproduction signal is automatically switched to the reproduction signal in the sub-DTR, so that the program program signal can be continuously transmitted.
This is aimed at stabilizing the quality of the program signal.

EXAMPLE An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows the connection of each part of a video/audio program transmission system in an embodiment of the present invention. In Figure 1, 11.12 is a main/sub digital video tape recorder or a digital audio tape recorder (
(hereinafter abbreviated as DTR), 13 is a flag comparison circuit (hereinafter abbreviated as FCHK) that compares flags from a signal inspection circuit (DCHK circuit) in the DTR, which will be described later; DTRll, 12
This is a program signal switching (hereinafter abbreviated as SW) circuit that selects a signal from the program signal.

FIG. 2 is a block diagram showing the internal configuration of the main DTRII in the present invention. In FIG. 2, 20 is a magnetic tape on which program program signals are digitally recorded;
1.22 is a magnetic head, 23.24 is a high frequency (hereinafter abbreviated as RF) circuit that amplifies and demodulates the head output, 25.26
27.28 is a signal processing circuit for decoding the digital signal; 29.30 is an error correction circuit for correcting errors in the digital signal; 31 is for temporarily storing the previously reproduced signal. memory for keeping
32 is a flag comparison (hereinafter abbreviated as DCHK) circuit for comparing and checking the coincidence of the previously reproduced signal and the subsequently reproduced signal; 33 is a digital circuit that converts the digital signal applied to the digital signal input terminal into an analog signal; 34 is a low-pass filter, and 35 is a low-frequency amplifier.

In addition, the sub-DTR has the same configuration as the above-mentioned upper DTR, or at least 21, 22.23, 24.25.2B,
27, 28.29. It is sufficient to have blocks of 30, 31, and 32.

The operation of the video/audio program transmission system of this embodiment configured as described above will be described below.

First, in FIG. 1, magnetic tapes for broadcasting programs on which exactly the same program program signals are digitally recorded are set in the main DTR II and the sub DTR 12.
Since the runs of R are connected by a time code (hereinafter abbreviated as TC), the runs of each tape are completely synchronized in time.

Next, let us consider the main D running in synchronization with such TC.
The reproduction operation of the program program signal within TRII will be explained.

In FIG. 2, a signal reproduced from a magnetic tape 20 by a pre-reproducing head 21 is amplified and demodulated by an RF circuit 23, and shaped into a square wave of a digital signal by a waveform shaping (hereinafter abbreviated as EQ) circuit 25. This square wave is converted into a video or audio digital signal by a signal processing (hereinafter abbreviated as DEC) circuit 27.

However, if a signal error occurs in the reproduced signal due to a reading error or the like during this process, the error correction (hereinafter abbreviated as ECC) circuit 29 will completely correct the normal error. In this case, there is no difference between the recorded original program signal and the corrected signal. Also, E.C.C.
If the correction limit of the circuit 29 is exceeded, a correction operation is performed, and for example, the signal between the errors is complemented based on the signals before and after the error has occurred. In this case, a difference occurs in the complemented portion between the original program signal and the complemented signal.

The program signal thus pre-reproduced and subjected to signal processing is temporarily stored in a memory (hereinafter abbreviated as MEM) 31, and time-matched with the program program signal to be reproduced later.

On the other hand, the program signal reproduced later by the head 22 is similar to the program signal reproduced earlier by the RF
From the circuit 24 to the DCHK circuit 3 via the DEC circuit 28
2 is input. The DCHK circuit 32 includes the aforementioned MEM
Since the advance playback signal of the same time from 31 is also input,
These two signals are compared point by point to check whether the signals match or do not match. As described above, if there is a signal complement or a signal is missing, the signal comparison result will be a mismatch, and the flag output of the DCHK circuit 32 will be set to a high level.

The reproduction operation of the program program signal in the main DTR II has been described above, but the exact same reproduction operation is performed in the sub DTR 12 as well. Therefore, depending on whether the flag output of the DCHK circuit 32 is high level or low level, the first
The quality of the program signal reproduced by the FCHK circuit 13 shown in the figure can be judged.

Next, the connection of the reproduced program program signal to the digital signal input (hereinafter abbreviated as Din) terminal of the main DTR will be explained based on FIG.

The D CHK outputs from each of the ports and TRs are input to the FCHK circuit 13, and the program program signal from Dout is input to the SW circuit 14, respectively. Here, Lord D
If an abnormality occurs in the TRII playback signal, such as a decoding error or a signal dropout due to a DTR malfunction, the main DTi
Since the DCHK output from 'jll is high level,
FCHK circuit 113 detects an abnormality in the main DTRII and
A control signal output for selecting and switching the Dout output is transmitted to the W circuit 14.

In the SW circuit 14, Dout is selected based on this control signal and is switched to the sub DTR 12. The switched Dout signal is converted into an analog signal by the D/A converter 33 in FIG.
The signal is sent from the t terminal to the transmitter as an analog program signal.

As described above, according to this embodiment, even if an abnormality occurs in the two main DTRs operating in parallel and synchronously, the program signal to be reproduced by the sub DTR is automatically selected, and the program signal is sent to the transmitter. can always send out a normal program signal.

Of course, according to the configuration of this embodiment, from the secondary DTR to the main DTR
Automatic switching to TR is also possible.

Effects of the Invention As described above, the present invention compares and inspects two systems of signals, that is, the preceding playback and the following playback, so that the quality of the reproduced signal is judged with high accuracy, and the judgment is performed in the signal decoding process of the signal processing block. Therefore, there is no switching time delay. Furthermore, signal switching is performed in the digital signal state, and then D/'A
Since the conversion is performed, the continuity of the signal is maintained.

As described above, according to the program transmission system of the present invention, compared to the conventional system, there is no interruption time and the switching signal is
Since there is no ticking sound, its practical effect is great.

[Brief explanation of drawings]

Fig. 1 is a system diagram of a video/audio signal and transmission system according to an embodiment of the present invention, Fig. 2 is a block diagram of a DTR of the same embodiment, and Fig. 3 is a system diagram of a conventional video/audio signal transmission system. Ah kudzu. 1, 2...Analog tape repuder, 3.4...
Signal detection circuit, switch circuit, flag comparison circuit, 20...magnetic tape, 23.24...RF circuit, 27.28...DEC circuit, circuit, 31...MEM. 33...D/A circuit, MP circuit. Name of agent Patent attorney vote! l'F Shigetaka Haka 1 person 5... Judgment circuit, 6... Switching 11.12.
...DTR, 13... 14...Dout switching circuit, 21.22...Magnetic head 2 [5, 26...EQ circuit 29.30...ECC 32...DCHK circuit, 34. ...f, PFl 35...A figure 7 skewer diagram

Claims (1)

[Scope of Claims] At least one pair of magnetic recording/reproducing heads for performing preceding reproduction and subsequent reproduction, a signal processing block for the reproduced signal, a memory dedicated to the previously reproduced signal, preceding reproduction and subsequent reproduction. two digital tape recorders, each of which has a signal inspection circuit that compares and inspects each signal, and operates these two digital tape recorders temporally in synchronization based on time code information; and the signals of the two digital tape recorders. A flag comparison circuit that compares the flag output based on the pass/fail inspection results from the inspection circuit; and a flag comparison circuit that operates in conjunction with this flag comparison circuit to compare the program program signals that have higher quality between the two digital tape recorders reproduced. A video/audio program transmission system comprising: a signal switching circuit that automatically selects a signal.