KR100418653B1 - RF monitoring direction controled Wireless CCTV system using the same frequency band - Google Patents

Abstract

The present invention is to improve the shortcomings of the conventional fixed wireless CCTV system that requires one camera in each direction in order to monitor multiple directions in a fixed area, by wirelessly adjusting the monitoring direction of the wireless CCTV system to one camera It is about how to monitor the desired direction.

In the present invention, since the non-modulated radio control frequency used to adjust the monitoring direction wirelessly uses the same frequency band as the frequency used when transmitting a video signal, the conventional bidirectional adjustment method requiring an additional radio frequency for adjusting the monitoring direction. Has the feature of improving the disadvantages.

The control method according to the present invention transmits a camera adjustment control signal using a wireless remote controller or an adjustment terminal attached to a receiver main body on the side of receiving an image, and the monitoring camera periodically monitors whether a signal for adjusting the direction of the camera is received. When the direction control signal is received, the direction control motor is driven to change the monitoring direction of the camera.

Description

{RF monitoring direction controled Wireless CCTV system using the same frequency band}

The CCTV system is intended to monitor video and audio from a remote location, and is composed of a video transmission unit for transmitting images and a monitor unit for viewing the received images on a monitor, and its use is spreading for remote monitoring. There are two types of transmission media: wired and wireless. Wired CCTV systems connect the video transmitter and the monitor by wire, which has the advantage of excellent video and audio quality, but it is necessary to connect wires all the time. It is disadvantageous in places where wealth must be moved frequently. On the other hand, the wireless CCTV system is somewhat inferior to the wired video and audio quality, but has advantages in places where the human body is dangerous or difficult to install wired.

The present invention relates to a wireless CCTV system, and more particularly to a wireless CCTV system for transmitting an unmodulated control signal simultaneously with an audio and video signal in order to wirelessly control the monitoring direction of the camera.

Fixed wireless CCTV system, which is a conventional wireless video transmission system, has been using a unidirectional (simplex) communication method that simply transmits a video or video and audio signal to monitor a signal input to a camera. This method is a fixed monitoring method that can not adjust the monitoring direction at the receiver after installing the wireless CCTV once. Therefore, the fixed monitoring method has the disadvantage of installing several surveillance cameras in order to monitor various directions.

1a and 1b show the configuration of the transmitter and receiver of the conventional fixed wireless CCTV system, respectively. Referring to the drawings, a conventional technique is as follows. FIG. 1A is a diagram illustrating a wireless CCTV transmitter for transmitting video and audio. The video signal input through the CCD camera 101 is converted into an electric * signal by the CCD camera main body 102. FIG. The video signal is input to the wireless transmitter 104 together with the audio signal input from the microphone 103. After the frequency upconversion by the modulation and frequency generator 105, the video signal is transmitted wirelessly through the transmission antenna 106. . FIG. 1B illustrates a signal transmitted from a CCTV through a reception antenna 107, down-converted in frequency through an oscillator 109 in a wireless receiver 108, and demodulated and then demodulated and transmitted. Video and audio signals are output through the and speaker 111, respectively.

Recently, in order to solve the above problem, US patent US5079634: Apparatus for wireless-controlling a camera and apparatus for two-direction simultaneous control of electrically driven equipment in order to remotely control the monitoring direction at the monitoring location is a bidirectional monitoring and monitoring unit. Is a patent that transmits the status of cameras to each other or adjusts the monitoring direction of the cameras. Since the transmission and reception frequencies are used differently for bidirectional communication, additional radio frequency allocation is required, and duplexer is needed as an additional component.

On the other hand, US5305100: Bidirectional communication system for CCTV has the concept of extending the US5079634, which selects one of four cameras to adjust the monitoring direction as well as to know the status of the camera. However, this system also transmits video signals wirelessly and uses infrared rays to control the direction of the camera. Therefore, it is impossible to select a camera and adjust the monitoring direction in a non-visible area.

In the present invention, in order to improve the problems as described above, the purpose of adjusting the monitoring direction of the camera from a remote location by using an unmodulated radio frequency (Radio frequency), and the radio frequency used for remote control in particular in the wireless CCTV Since the same frequency band used for transmitting the video signal is used to improve the disadvantage of the conventional two-way adjustment method that requires an additional radio frequency for adjusting the monitoring direction.

1a and 1b is a block diagram of a conventional wireless CCTV system

Figure 2a is a wireless CCTV monitoring unit according to the present invention

2b is a wireless CCTV monitor unit according to the present invention

Figure 3a shows the output of the normal period generating circuit

3b is the output of the monitoring unit control cycle generating circuit

3c is the output of the monitor control cycle generation circuit.

4 is a control cycle generation circuit of the monitor unit

5a shows the output of the multivibrator

5b shows the output of the constant control period generating circuit.

6 is a frequency bandwidth for conventional video and audio transmission

Figure 7a shows the position of the control tone frequency according to the present invention

Figure 7b is a use example of the camera direction control signal according to the present invention

※ Explanation of code for main part of drawing

208: camera direction adjustment unit 207, 222: transmission and reception switch

212: period generation selection switch 213: normal cycle generation circuit

214: monitoring unit control cycle generating circuit 210: control tone detection circuit

211: camera direction control signal detector 215: camera direction driver

227: camera direction adjustment transmitter 220: control direction switch

229: control signal generator 230: control tone generator

232: control cycle generation circuit of the monitor

In order to improve the conventional wireless CCTV system described above, the present invention consists of two parts. First, a monitoring unit (Fig. 2a) that receives control signals while transmitting video and audio to adjust the monitoring direction of the camera, and second, receives and monitors signals transmitted from the monitoring unit. It is comprised by the monitor part (FIG. 2b) which has a function which adjusts a direction wirelessly.

The monitoring unit includes a transmitter comprising a camera 201, a CCD camera main body 202, a microphone 203, a radio transmitter 204, a frequency generator 205, an antenna 206, a transmission / reception switching switch 207, a frequency converter. 209, control tone detection circuit 210, camera direction control signal detection unit 211, period generation selection switch 212, normal period generation circuit 213, monitoring unit control period generation circuit 214, camera direction driver It is comprised by the camera direction adjustment part 208 comprised by 215. As shown in FIG.

Meanwhile, the monitor unit includes an antenna 221, a transmission / reception switch 222, a wireless receiver 223, a frequency generator 224, a monitor 225, and a speaker 226. 228, a control signal generator 229, a control tone generator 230, a frequency up-converter 231, and a control direction generator 232 composed of a camera direction adjustment transmitter 227.

Referring to the operation of the present invention using a picture as follows. FIG. 2A shows the configuration of the monitoring unit. In FIG. 1A which is a conventional system, a camera direction adjusting unit 208 capable of remotely adjusting the monitoring direction of the camera is added. The function of transmitting an image from the camera 201 through the antenna 206 is the same as that of FIG. 1a, but the signal received from the antenna 206 passes through the frequency converter 209 after passing through the transmission / reception switching switch 207. In this case, the frequency generator 205 used at the time of transmission for frequency downconversion is commonly used.

The output of the frequency converter 209 is input to the control tone detection circuit 210 and the camera direction control signal detection unit 211. First, if the control tone is not detected in the control tone detection circuit 210, the period generation selection switch 212 is connected to the normal period generation circuit (213). However, when the control tone is detected, the period generation selection switch 212 is connected to the monitoring unit control period generation circuit 214. On the other hand, the transmission and reception switching switch 207 is transmitted or received by the output of the period generation selection switch. The signal input to the camera direction control signal detector 211 is input to the camera direction driver 215 after detecting the direction control signal to change the direction of the CCD camera main body 202.

FIG. 2B shows a monitor portion, in which a camera direction adjustment transmitter 227 capable of remotely adjusting the monitoring direction of the camera is added to FIG. 1B, which is a conventional system. The function of receiving video and audio from the antenna 221 is the same as that of FIG. 1B, but the output of the control direction switch 228 of the camera direction adjustment transmitter 227 is the control tone generator 230 and the control signal generator 229. And it is connected to the transmission and reception switch 222, when the control direction switch is selected first, the control tone generator 230 generates a control tone irrespective of the control direction of up, down, left, and right. The control signal generator 229 generates a corresponding control signal according to the selection of the control direction switch (for example, to generate a control frequency corresponding to up, down, left, and right to move the camera position up, down, left, and right). After the output of the control signal generator 229 and the output of the control tone generator 230 are summed up with each other, the frequency up-converter 231 is raised to the transmission frequency by the frequency generator 224 and then the transmission / reception switching switch 222 Is entered. The transmission / reception switching switch 222 is connected to the wireless receiver 223 in a normal state, but when any one of the control direction switches 220 operates, the transmission / reception switching switch 222 is driven by driving the control period generating circuit 232. Switch to.

3 is a timing diagram for explaining the operation of the transmission / reception switching switch 207 and the period generation selection switch 212 of FIG. 2A. 3A shows the output of the normal period generating circuit 213. In the normal state, that is, when no control signal is transmitted from the monitor unit, the period generation selection switch 212 is connected to the normal period generation circuit 213, and the transmission / reception switching switch 207 is the normal period generation circuit shown in FIG. 3A. If the output of the logic " 1 " is connected to the output of the radio transmitter 204 of Fig. 2a, and the logic " 0 " Therefore, in the steady state, the transmission time is longer than the reception time.

If a control signal is received during a steady state reception time (hereinafter referred to as a control state), the control tone detection circuit 210 detects an unmodulated control tone and the period generation selection switch 212 controls the monitoring unit control period generation circuit ( 214). 3B shows the output of the control period generating circuit. The transmission / reception switching switch 207 is also connected to the output of the radio transmitter 204 of FIG. 2A if the output of the control period generating circuit is logic " 1 " Is connected to the input of frequency converter 209. Therefore, in the control state, the reception time is longer than in the normal state, so that the direction of the camera can be smoothly adjusted according to the control signal transmitted from the monitor unit.

FIG. 3c illustrates the output of the control cycle generation circuit of the monitor unit. In the normal state, the monitor unit is connected to the wireless receiver 223 to receive the input signal. However, in the control state, control and reception must be performed simultaneously. Therefore, if the output of the monitor control period generation circuit is a logic "1", the transmission and reception switching switch 222 is connected to the frequency up-converter 231, if the logic '0' is connected to the radio receiver 223. Comparing FIG. 3C and FIG. 3B, it can be seen that the phases are reversed from each other. This is a mode in which the monitoring unit receives the control signal when the monitor unit transmits the control signal (logic “1” in FIG. 3C) according to FIG. 3C. (The logic "0" in FIG. 3b), on the contrary, when the monitoring unit transmits the video and audio signals (the logic "1" in FIG. 3b), the monitor unit receives the mode (the logic "0" in FIG. 3c). For sake. Therefore, the monitor unit generates a control signal for adjusting the direction of the camera, but simultaneously receives the video and audio signals transmitted from the monitoring unit.

As shown in FIG. 3C and FIG. 3B, it can be seen at the beginning of the timing diagram that the length of logic "1" (FIG. 3C) or logic "0" (FIG. 3B) is long, which is the normal position of the wireless CCTV monitoring unit. When the output of the period generating circuit (Fig. 3A) is a logic " 0 ", it is a period during which the camera unit receives a signal transmitted from the monitor unit. Even if the monitor unit operates the control direction switch (228 of Fig. 2B) at any time, The period of generating the control signal of the monitor unit is extended so that the camera unit can detect the timing regardless. That is, if the control signal generation period is longer than two cycles of the output of the normal period generation circuit (Fig. 3A), the output of the normal period generation circuit of the camera unit (Fig. 3A) regardless of the timing of operating the control direction switch (228 in Fig. 2B). The logic " 0 " After the initial state, the control signal generation period is stably equal to the period of logic " 1 " and the period of logic " 0 ".

4 is a block diagram of the control cycle generating circuit 232 of the monitor unit for outputting FIG. 3c, the signal input to the control cycle generating circuit is a monostable multivibrator 402 and a constant control cycle generating circuit 401 And each output is logically added in the OR circuit 403 to produce the output of the control period generating circuit. FIG. 5A shows the output of the monostable multivibrator, and FIG. 5B is the output of the constant control period generation circuit 401. FIG. The output of the logical sum circuit 403 is a signal obtained by performing a logical sum of the Figs. 5a and 5b, which is the same as the 3c.

6 shows a typical band for transmitting a typical video and audio, which is a typical occupied bandwidth used for transmitting video and audio, and the audio uses a subcarrier of 4.5 MHz (may vary slightly from system to system). It is located in the higher frequency band than the video signal. FIG. 7a shows the control tone frequency position 701 according to the present invention, as shown in FIG. 6, placing the control tone frequency in an unused bandwidth between 4 MHz and 4.5 MHz. Figure 7b shows an example of the use of the camera direction control signal according to the present invention, the four frequencies (702, 703, 704, 705) for adjusting the camera direction up, down, left and right are located between 0 Hz and 4 MHz, the control Tone 706 shows an example located at 4.25 MHz. In order to adjust the direction of the camera only up and down or left and right, only two control signals need to be used. As described in FIG. 3, since the video and audio signals and the control signal are not transmitted simultaneously, mutual interference does not occur even if they are transmitted using the same frequency band. In Fig. 7a and Fig. 7b, the dotted line is shown as a reference to indicate the same frequency band, and the solid line represents the control tone and the control signal.

The conventional fixed wireless CCTV system has a disadvantage in that each camera requires a monitoring direction in order to monitor various directions at a designated place. Recently, a method of controlling a monitoring direction of a camera by using a bidirectional communication method has been introduced to improve such a disadvantage. The bidirectional communication method also includes a frequency for transmitting an image and a frequency for transmitting a direction control signal of a camera. There was a problem requiring two separate frequencies.

The present invention improves the monitoring direction fixing method that has been pointed out as a disadvantage of the conventional fixed wireless CCTV system is a method that can easily change the monitoring direction of the camera at any time using wireless, without assigning additional radio frequency for monitoring direction control In the conventional wireless CCTV system, there is an effect that can easily control the monitoring direction of the camera using the same frequency band used to wirelessly transmit video and audio.

Claims (6)

In a wireless CCTV system that modulates the video and audio signals input from the camera and the microphone and transmits them wirelessly, demodulates the received signals and recovers the signals transmitted through the monitor and the speaker. A monitoring unit adjusting a monitoring direction of a camera by receiving an unmodulated control signal of the same frequency band while transmitting an image and audio to wirelessly adjust a monitoring direction of the wireless CCTV system; And a monitor unit having a function of receiving and monitoring video and audio signals transmitted from the monitor unit and wirelessly adjusting the camera direction of the monitor unit using the same unmodulated frequency. The apparatus of claim 1, wherein the monitor unit comprises a camera direction adjustment transmitter including a control direction switch, a control signal generator, a control tone generator, a frequency up-converter, and a control period generator to wirelessly adjust the direction of the camera. Wireless CCTV system. The apparatus of claim 1, wherein the monitoring unit receives a camera monitoring direction control signal transmitted wirelessly from the monitor unit and detects a transmission / reception switch, a frequency converter, and a control tone to adjust the camera direction up, down, left, or right (or up, down, left, or right). Wireless CCTV system comprising a camera direction control unit consisting of a circuit, a camera direction control signal detection unit, a cycle generation selection switch, a normal cycle generation circuit, a monitoring unit control cycle generation circuit, a camera direction driver. The apparatus of claim 1, further comprising a timing generator so as to be sufficiently recognized by the monitoring unit by lengthening the period of the initial control signal in order to prevent the collision between the transmission and reception signals when the initial control signal is generated to wirelessly adjust the direction of the camera. Wireless CCTV system. The wireless CCTV system according to claim 1, wherein a transmission / reception switch is used to monitor and monitor the image and audio signals and control signals. The wireless CCTV system according to claim 1, wherein the control tone and the control signal are used within the video and audio bandwidth.