JPH01265673A - Video recording system - Google Patents

Abstract

PURPOSE:To avoid crosstalk by detecting a crosstalk caused in a radio signal and switching a reception frequency or a transmission frequency in a video camera and a video recorder sending a video signal in a radio signal. CONSTITUTION:When a video recorder 2 detects a crosstalk in a reception signal of a channel ch1, a crosstalk detection signal is brought into an H level and a channel revision command is sent. When a video camera 1 receiving it switches the transmission frequency from the channel ch1 into a channel ch2. The recorder 2 detects the missing of the reception signal of the ch1, brings the level detection signal 2e into an L level and switches the reception frequency from the ch1 into the ch2. Then the recording signal 2g is switched into a recovered synchronizing signal 2d till the reception signal appears on the ch2 and it is recorded. When the reception signal level rises, the level of the signal 2e goes to an H level and the signal is switched into the signal demodulating the reception signal. Thus, the disturbance of the picture due to crosstalk is avoided.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a video camera that wirelessly transmits video signals;
This invention relates to a video recording system comprising a video recording device that receives and records or displays the received signal, and particularly to a video recording system that avoids interference of wireless signals.6 [Prior Art] In recent years, video recording devices that record video signals have been used.

That is, with the development of video tape recorders and video cameras, even individuals can now easily take videos using video cameras. Conventionally, methods for connecting a video camera and a video tape recorder include a method of connecting with a signal cable line, a method of integrating the video camera and a video tape recorder in the same housing, and a method of connecting the video camera and the video tape recorder in the same housing. There is a method of realizing signal transmission using radio waves, as described in Japanese Patent No. 97781.

[Problems to be Solved by the Invention] Among the above-mentioned methods, the method of realizing signal transmission using radio waves does not require a connection cable and improves operability. Furthermore, compared to an integrated type that combines a video camera and a video tape recorder, only the camera part can be moved, so it has the advantage of being smaller and lighter.

In this way, when using technology that uses radio waves.

Although it has the advantages mentioned above, it also has the problem of interference.

For example, if a video camera approaches another camera that uses the same frequency while it is moving, interference may cause image distortion, and it is possible that reception will eventually become impossible. The above-mentioned conventional technology does not take into account the prevention of this interference, and if interference occurs during shooting, the camera operator will not be able to know that it has occurred.
It was extremely inconvenient that the interference occurred only when the recorded videotape was played back after the shooting.

In addition, as one of the shooting methods, a video camera may be fixed at a specific position, and a video tape recorder may be installed at another location to take pictures.

In this type of configuration, the operator is close to the video tape recorder and operates the video tape recorder while viewing images from the video camera.

If interference occurs in this state, the operator can tell from the disturbance of the video, etc., but there is also the problem that effective measures to avoid interference cannot be taken because the video camera is far away.

The present invention has been made in order to solve the above-mentioned problems, and its purpose is to provide a video recording image system that enables the use of multiple transmission frequencies and avoids the occurrence of interference. An object of the present invention is to provide a video recording system that reduces image quality deterioration that occurs when using frequencies.

[Means for Solving the Problems] In order to achieve the above-mentioned object of avoiding interference, the present invention provides a video camera with a first transmitter that transmits a signal modulated by a video signal as a first transmission signal using radio waves. a transmitting means, a first receiving means for receiving and demodulating a second transmission signal transmitted by radio waves from a video recording device and reproducing a control signal, and the control signal reproduced by the first receiving means. Follow the signals.

a first changing means for changing the transmission frequency of the first transmitting means and the receiving frequency of the first receiving means to different frequencies in synchronization with a synchronization signal of the video signal, and , a second receiving means for receiving and demodulating the first transmission signal transmitted by radio waves from the video camera and reproducing the video signal; and a second receiving means for reproducing the video signal by the second receiving means. video recording means for recording the transmitted video signal; interference detection means for detecting whether or not interference has occurred in the first transmission signal received by the second reception means; and the interference detection means. control signal generating means for generating the control signal when detecting the occurrence of interference;

a second transmitting means for transmitting a signal modulated by the generated control signal as the second transmitting signal via radio waves; and presence or absence of the first transmitting signal received by the second receiving means. a signal presence/absence detection means for detecting the absence of a signal; and a transmission frequency in the second transmission means in synchronization with a reproduction synchronization signal reproduced from a synchronization signal of the video signal when the signal presence/absence detection means detects that there is no signal. Second changing means for changing the reception frequency in the second receiving means to different frequencies, respectively, are provided.

In addition, in order to achieve the purpose of reducing image quality deterioration mentioned above,
In the present invention, the video recording device further includes a synchronization separating means for separating the synchronizing signal from the video signal reproduced by the second receiving means, and reproducing the reproduced synchronizing signal from the synchronizing signal separated by one. the video signal and the reproduction synchronization signal are inputted, and during a period in which the signal presence/absence detection means detects that the signal is present, the video signal is detected as being absent. and selecting means for selecting each of the reproduction synchronization signals and outputting them to the video recording means in the period, or
storage means for storing the video signal reproduced by the second receiving means; and the video signal reproduced by the second receiving means (hereinafter referred to as the first video signal).
and a video signal read out from the storage means (hereinafter referred to as the second video signal), and of the two, during the period in which the signal presence/absence detection means detects that the signal is present, the first video signal is input. A selection means is provided for selecting the second video signal and outputting it to the video recording means during a period when no video signal is detected.

[Operation] In order to avoid interference, each of the above-mentioned means operates as follows.

First, the video recording device receives the first transmission signal from the video camera using the second receiving means, demodulates it, and reproduces the video signal.

The reproduced video signal is recorded by the video recording means. At this time, when the first transmission signal receives interference from another device, the video recording device detects this with the interference detection means, generates the control signal with the control signal generation means, and generates the control signal with the control signal generation means. A second transmission means transmits the second transmission signal to the video camera.

On the other hand, the video camera receives the second transmission signal by the first receiving means and demodulates it to generate the control signal. Then, in accordance with the reproduced control signal, the first changing means changes the transmission frequency of the first transmitting means to the first receiving means in synchronization with a synchronization signal of the video signal. and the receiving frequency at each of them are changed to different frequencies.

In this way, when the transmission frequency in the first transmitting means is changed to another frequency, the first receiving signal received by the second receiving means in the video recording apparatus is interrupted, so that the signal The absence of the signal is detected by the presence/absence detection means, and the second changing means synchronizes with a reproduction synchronization signal reproduced from the synchronization signal of the video signal.

The transmitting frequency in the second transmitting means and the receiving frequency in the second receiving means are changed to different frequencies. At this time, the receiving frequency in the second receiving means is the same as the transmitting frequency in the first transmitting means, and the transmitting frequency in the second transmitting means is the receiving frequency in the first receiving means. By changing the signal so that it is the same as that, the second reception means can receive the first reception signal again.

As described above, according to the present invention, even if interference occurs, the interference is detected and the receiving frequency and the transmitting frequency are switched, so that interference can be avoided.

Furthermore, in order to reduce image quality deterioration, each of the above-mentioned means operates as follows.

In the video camera, the transmission frequency in the first transmission means is changed to another frequency, and as a result, in the video recording device, the first reception signal received by the second reception means is changed to another frequency. When the video signal is interrupted, the video signal recorded by the video recording means is also interrupted.

Therefore, in the present invention, the selection means outputs the reproduction synchronization signal from the synchronization reproduction means to the video recording means during the period when the first reception signal is interrupted.

Therefore, according to the present invention, this occurs due to the interruption of the first received signal. This has the effect of reducing image quality deterioration due to loss of synchronization or noise.

Further, when the second video signal read from the storage means (for example, a video signal of one frame before) is output to the video recording means instead of the reproduction synchronization signal, the image quality may deteriorate. This has the effect of further reducing .

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention.

In the figure, 1 is a video camera, 2 is a video recording device, 10.20 is an antenna, 11.21 is a duplexer, 12.
22 is a demodulation circuit, 13.23 is a channel control section, 14 is a synchronization signal generation circuit, 15 is a microphone, 16 is an audio processing circuit, 17 is an imaging section, 18 is a video signal conversion section, 19
．． 26 is a modulation circuit, 24 is a synchronization control section, 25 is a video tape recorder (hereinafter referred to as VTR) section, la and 2a are transmission carrier signals, lb is a synchronization signal, lc and 2c are demodulation signals, ld and 2b are reception 2d is a frequency control signal, 2d is a reproduction synchronization signal, 2e is a level detection signal, 2f is a channel change instruction signal, and 2g is a recording signal.

Next, the configuration and operation will be explained.

First, in the video camera 1, audio and video input, which will be described from the transmission system, are performed by a microphone 15 and an imaging section 17, respectively. The audio input by the microphone 15 is passed through the audio processing circuit 16, where it is amplified and filtered, and is input to the modulation circuit 19 as an audio signal. On the other hand, the image is input from the imaging section 17 to the video signal converting section 18 .

The synchronization signal 1b output from the synchronization signal generation circuit 14 is also input to the video signal converter 18, whereby the video is converted into a video signal including synchronization, and like the audio signal,
The signal is input to the modulation circuit 19.

The modulation circuit 19 modulates the transmission carrier signal 1a output from the channel control section 13 using the above two types of signals and outputs the modulated signal. This modulated signal is sent to the antenna 1 via the duplexer 11.
0 to the video recording device 2. The frequency of this transmission output is determined by the channel control section 13 as described later.

Next, the reception system of the video camera 1 will be explained. A received signal received from antenna 10 is input to demodulation circuit 12 via duplexer 11 . This received signal is transmitted to the demodulation circuit 12
After demodulating with
3 is output. Here, the control signal 1d output by the channel control section 13 determines the reception frequency.

Next, the channel control section 13 will be explained.

FIG. 2 is a block diagram showing the channel control section 13 of FIG. 1.

In the figure, 130 is a data identification circuit, 131 is a control circuit, 132 is a transmitting synthesizer section, 133 is a receiving synthesizer section, 18 is an identification signal, and other components equivalent to those in FIG. 1 are given the same reference numerals. The demodulated signal IC output from the demodulation circuit 12 is input to the data identification circuit 130. The data identification circuit 130 identifies whether or not the demodulated signal 1c is a channel change command sent from a video recording device, and outputs an identification signal 1e. The identification signal 1e is input to the control circuit 131.

The control circuit 131 receives the synchronization signal 1b output from the synchronization signal generation circuit 14, and l! Separate double signal 1e
If it appears, a channel change signal is output within the vertical synchronization period obtained from the synchronization signal 1b. The channel change signal is input to the transmission synthesizer section 132, and the synchronizer 132 receives this □ and switches the frequency of the transmission carrier signal 1a currently being output. As a result, the transmission frequency of the video camera 1 changes. The transmission carrier wave signal 1a is transmitted to the channel control section 13.
It is branched internally and manually input to the reception synthesizer section 133.

At synchronization 133, a signal having a certain frequency lower than the input signal frequency is output to the demodulation circuit 12 as a reception frequency control signal 1d. Therefore, the reception frequency changes while maintaining a constant interval from the transmission frequency.

The above is the configuration and operation of the video camera 1.

Next, a receiving system of the video recording device [2] connected to the video camera 1 via a wireless line will be explained. A signal received by the antenna 20 shown in FIG. 1 is input to the demodulation circuit 22 via the duplexer 21. The circuit 22 demodulates a signal at a frequency determined by the reception frequency control signal 2b output from the channel control section 23. Here this frequency is.

It is assumed that the transmission frequency matches the transmission frequency of the video camera 1. This demodulated signal 2c is branched and output to the channel control section 23 and synchronization control section 24.

Here, the channel control section 23 will be explained.

FIG. 3 is a block diagram showing the channel control section 23 of FIG. 1.

In the figure, 230 is an interference detection circuit, 231 is a channel data generation circuit, 232 is a level detection circuit, 233 is a reception synthesizer section, 234 is a transmission synthesizer section, 2
3a is an interference detection signal, and other components equivalent to those in FIG. 1 are given the same reference numerals.

The branched output demodulated signal 2c is sent to the channel control section 23.
The signal is branched within the circuit, and one side is input to the interference detection circuit 230 and the other side is input to the level detection circuit 232. The interference detection circuit 230 receives the reproduced synchronization signal 2d output from the synchronization control section 24 of FIG. 1, and detects interference to the receiving channel of 1 gA during the vertical synchronization period obtained thereby.

It is output as an interference detection signal 23a.

The interference detection signal 23a is input to a channel data generation circuit 231, and the circuit 231 outputs a channel change command as a channel change instruction signal 2f when the interference detection signal 23a appears. The circuit 232 inputs the above-mentioned signal 2c and, like the interference detection circuit 230, inputs the reproduction synchronization signal 2d, and detects the transmission signal of the video camera 1 in the vertical synchronization period obtained by this synchronization signal 2d. disappearance,
That is, it detects and outputs the switching of the transmission channel, and this detection output is used as a level detection signal 28.

The signal is output to the synchronization control section 24 in FIG. 1, and branched and input to the reception synthesizer section 233.

When the reception synthesizer section 233 learns of the disappearance of the transmission signal from the level detection signal 2e, it changes the settings in the reception synthesizer section 233 so as to switch the frequency of the reception frequency control signal 2b. The reception frequency control signal 2b is also input to the transmission synthesizer section 234. In synchronization 234, a signal having a certain frequency lower than the input reception frequency signal 2b is output as the transmission carrier wave signal 2a so as to match the reception frequency of the video camera 1. Thereby, the transmission and reception frequency of the video recording device 2 can be made variable like the video camera 1.

The above is the configuration and operation of the channel control section 23.

The channel change instruction signal 2f output from the channel control section 23 is input to the modulation circuit 26 shown in FIG. The same circuit 26 similarly receives the transmission carrier wave signal 2a outputted from the channel control section 23.

This is modulated with the channel change instruction signal 2f'.

The modulated signal is transmitted from the antenna 20 via the duplexer 21.

Next, the synchronization control section 24 will be explained.

FIG. 4 is a block diagram showing the synchronization control section 24 of FIG. 1.

In the figure, 240 is a synchronous separation circuit, 241 is a synchronous regeneration circuit, 242 is a switch, and other parts equivalent to those in FIG. 1 are given the same reference numerals.

The demodulated signal 2c outputted from the demodulation circuit 22 is internally branched, one of which is input to the synchronization separation circuit 240 and the other to the switch 242.

A synchronization signal is separated from the demodulated signal 2c in the synchronization separation circuit 240, and this signal is input to the synchronization regeneration circuit 241.

The same circuit 241 also inputs the level detection signal 2e output from the level detection circuit 232 shown in FIG. The signal is output as it is as the reproduced synchronization signal 2d, and when disappearance is detected, the synchronization separation circuit 24 immediately before the disappearance is detected.
The synchronization signal from 0 is maintained and output as a reproduction synchronization signal 2d.

Next, this reproduction synchronization signal 2d is input to the switch 242, and as described above, is input to the channel control section 23 shown in FIG. 1 for timing purposes, and is also input to the VTR section 25. The switch 242 is controlled by the level detection signal 2e, and outputs the reproduction synchronization signal 2d when the loss of the received signal from the video camera 1 is detected, and the demodulated signal 2c when the loss of the received signal is not detected.

They are switched and connected so that they are output as recording signals 2g. This makes it possible to minimize synchronization disturbances due to loss of received signals.

By the way, in this embodiment, the recording information transmission channel frequency from the video camera 1 to the video recording device 2 is set to a certain frequency higher than the channel control information transmission channel frequency from the video recording device 2 to the video camera in the opposite direction. ing. However, the frequency difference between the two channels should be set so that the interference detection circuit 230 in the video recording device 2 does not malfunction due to the transmission signal going around to the receiving side, and which frequency should be set higher. Needless to say, it's fine.

The operation of each component of this embodiment has been described above.

Next, the operation of this embodiment when interference occurs during photographing will be described with reference to FIG.

FIG. 5 is a signal waveform diagram for explaining the channel switching operation at the time of interference in FIG. 1.

In the figure, (a) indicates the transmission frequency of the video camera 1 (
In other words, the waveform of the signal in the initial signal channel chl determined by the reception frequency of the video recording device 2, (b
) is the waveform of the interference detection signal 23a, (C) is the waveform of the signal in the control channel determined by the transmission frequency of the video recording device 2 (in other words, the reception frequency of the video camera 1),
(d) is the waveform of the level detection signal 2e, (,) is the transmission frequency of the video camera 1 (in other words, the video recording device!!
! (f) is the waveform of the reproduction synchronization signal 2d, (g) is the waveform of the recording signal 2g,
In addition, A is the period until interference is detected, B is the period during which the received signals from the video cameras 1 and 2 disappear, and C is the period after the signal is detected in the switched signal channel ch2.

In the video recording device 2, when interference of the received signal in the signal channel ch1 is detected, the interference detection signal 23a is
I H11, and in response to this, the same equipment 2
A command to change the channel is sent using the control channel. When the video camera 1 receives this, it switches the transmission frequency and switches the signal channel from chl to ch2. As a result, in the video recording device 2, the signal channel chi
Assuming that the received signal at 2 disappears, the level detection signal 2
Set e to 11 L 11, switch the reception frequency, and switch the signal channel from chi to ch2. The above is the operation during period A. Here, each detection of interference and level is performed in synchronization with the reproduction synchronization signal 2d. Next period B
In the video recording device f! In 2.

The recording signal 2g is switched from the normal demodulation signal to the reproduction synchronization signal 2d until a reception signal appears on the newly switched reception channel ch2. When the level of the received signal in signal channel ch2 reaches a sufficient value, level detection signal 2
e becomes "■(". This change from "L" to "H" does not need to be synchronized with the above-mentioned reproduction synchronization signal 2d. From this, in period C, the recording signal 2g is in the signal channel ch2. 0 or more, in which the received signal is switched to a demodulated signal, is a rough channel switching operation when there is interference.

According to this embodiment, when there is interference, it is possible to avoid it by switching the channel. Also, the channel switching is performed in synchronization with vertical synchronization, and when the received signal disappears due to channel switching, the regenerated synchronization signal Since 2d is recorded, it has the effect of reducing disturbances in the recorded screen due to channel switching.

Next, a second embodiment of the present invention will be described.

In this embodiment, the synchronization control section 23 of the video recording device 2 in the first embodiment described above is changed to that shown in the block diagram of FIG. 6.

In the same figure, 24' is a synchronization control section in this embodiment;
243 is a frame memory, and other parts equivalent to those in the first embodiment are given the same reference numerals.

The feature of this embodiment is that when the received signal disappears, the image stored in the frame memory immediately before is output as the recording signal 2g during the period B in FIG. 5, and its structure and operation are synchronized. The synchronization signal and level detection signal 2e output from the separation circuit 240 are input as control signals, and using these, a frame memory 243 that stores one frame of demodulated signal 2c is used, and the output of this and the demodulated signal 2c are sent to the switch 242. The switch 242 is switched by the level detection signal 2e, and the other parts are the same as in the first embodiment.

According to this embodiment, there are effects similar to those of the first embodiment.

[Effects of the Invention] As explained above, according to the present invention, even if interference occurs, the interference is detected and the receiving frequency and the transmitting frequency are switched, so that interference can be avoided. .

In addition, when the frequency is switched, the recorded video signal is switched to the playback synchronization signal or the video signal read from the storage means (for example, 1 frame memory), so it is possible to reduce image disturbance, that is, deterioration in the quality of one image. It has the effect of saying.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention;
The figure is a block diagram showing the channel control section of the video camera in FIG. 1, FIG. 3 is a block diagram showing the channel control section of the video recording device in FIG. 1, and FIG. 4 is a block diagram showing the channel control section of the video recording device in FIG. 1. A block diagram showing a control unit,
FIG. 5 is a signal waveform diagram for explaining the channel switching operation at the time of interference in FIG. 1, and FIG. 6 is a block diagram showing the synchronization control section of the video recording apparatus in the second embodiment of the present invention. . 1... Video camera, 2... Video recording device, 10
゜20... Antenna, 11.21... Duplexer, 12
゜22... demodulation and modulation circuit, 13, 23... channel control section. 14... Synchronization signal generation circuit, 15... Microphone, 16
...Audio processing circuit, 17...Imaging section, 18.
...Video signal converter, 19.26...Modulation circuit, 2
4... Synchronization control section, 25... VTR section, 130...
・Data identification circuit, 131...control circuit, 132, 2
34... Transmission synthesizer section, 133, 233...
Reception synthesizer section, 230...interference detection circuit, 23
DESCRIPTION OF SYMBOLS 1... Channel data generation circuit, 232... Level detection circuit, 240... Synchronization separation circuit, 241... Synchronization regeneration circuit. 242...Switch, 243...Frame memory. Tsuta 2 figure 3

Claims (1)

[Claims] 1. A video recording system comprising a video camera and a video recording device, wherein the video camera first transmits a signal modulated by a video signal.
a first transmitting means for transmitting a transmission signal by radio waves as a transmission signal; a first receiving means for receiving and demodulating a second transmission signal transmitted by radio waves from the video recording device to reproduce a control signal; in accordance with the control signal reproduced by the first receiving means, in synchronization with a synchronization signal of the video signal,
a first changing means for changing a transmission frequency in the first transmitting means and a receiving frequency in the first receiving means to different frequencies, and the video recording device wirelessly transmits a signal from the video camera. a second receiving means for receiving and demodulating the first transmission signal transmitted by radio waves and reproducing the video signal; and a video recording means for recording the video signal reproduced by the second receiving means. , interference detection means for detecting whether or not interference has occurred in the first transmission signal received by the second reception means; and when the interference detection means detects the occurrence of interference, the control signal is detected. control signal generating means for generating;
a second transmitting means for transmitting a signal modulated by the generated control signal as the second transmitting signal via radio waves; and presence or absence of the first transmitting signal received by the second receiving means. a signal presence/absence detection means for detecting the absence of a signal; and a transmission frequency in the second transmission means in synchronization with a reproduction synchronization signal reproduced from a synchronization signal of the video signal when the signal presence/absence detection means detects that there is no signal. A video recording system comprising: second changing means for changing the reception frequency in the second receiving means to different frequencies. 2. The video recording system according to claim 1, wherein the video recording device includes synchronization separation means for separating the synchronization signal from the video signal reproduced by the second reception means, and the separated synchronization signal. synchronous reproduction means for reproducing the reproduction synchronization signal from the input terminal, and inputting the video signal and the reproduction synchronization signal, and in a period in which the signal presence/absence detection means detects that the signal is present, the video signal is
During the period when no signal is detected, the reproduction synchronization signal is
A video recording system characterized by comprising: a selection means for selecting each and outputting the selected video to the video recording means. 3. The video recording system according to claim 1, wherein the video recording device includes a storage means for storing the video signal reproduced by the second receiving means, and a storage means for storing the video signal reproduced by the second receiving means. A video signal (hereinafter referred to as a first video signal) and a video signal read out from the storage means (hereinafter referred to as a second video signal) are input, and of both, the signal presence/absence detection means is selection means for selecting and outputting the first video signal to the video recording means during a period when a signal is detected and the second video signal during a period when no signal is detected; A video recording system characterized by being provided with.