JPH09149471A - Signal selecting and recognizing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of the whole facility, to secure a recognizing speed corresponding to the state change of a monitoring object and to extend a transmission distance without using an optical cable by supplying a power source to the signal detectors of the monitoring objects at plural places through a common cable and transmitting the signal of the detector to a receiving part through the same cable. SOLUTION: A coaxial cable 1 is used for transmitting the signal of the plural monitoring objects outputted from the detector 3 and for supplying a power source to the detector in common. The detector 3 is connected to another detector 3 by the coaxial cable 1 one after another to lead to the reception part by means of the coaxial cable 1. Then the detector 3 detects the state of the monitoring object by a sensor 2 and modulates a high-frequency signal oscillated by different frequencies for each detector 3 with the signal. Consequently an address recognizing and responding equipment is unnecessitated to attain the remarkable cost down of the equipment at the place of the monitoring object and to facilitate the addition of the detector 3.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for selectively recognizing a plurality of signals to be monitored by time-divisionally receiving them by a common receiving section.

[Prior Art] As a conventional technique, a telemeter system using a predetermined frequency by radio waves is used for recognizing a monitoring target placed in a remote place, such as a patient monitoring system in a hospital or a liquid level monitoring system in a river. There are many systems in which a monitoring target and its monitoring device (reception device) are connected one by one and put into practical use. Further, a so-called radio control system or a communication system such as a telephone, which has a mutual recognition device between a monitoring target and a monitoring device, has been put to practical use without any explanation. In the wired field as well, the one having the mutual recognition device as the monitoring target and the monitoring device is widely used, especially the telephone. Of these, in the case of use in factories and plants for the purpose of centrally monitoring the status of a remote monitoring target, there are many cases in which multiple monitoring targets and monitoring devices are connected one by one and monitored. Furthermore, among them, a system for scanning and monitoring a plurality of monitoring targets with a single monitoring device in a time division manner has been widely put into practical use for the purpose of reducing the equipment cost. As a practical example of the practical technique, a method in which a monitoring target is connected by three common cables for transmission / reception and a ground to obtain monitoring information has been put into practical use. As a method of connecting the signals of the plurality of monitoring targets with a common cable, an address is attached to each of the objects that generate the signals of the monitoring target, a device for recognizing the address at the monitoring target location is prepared, and between the monitoring devices. Are connected to each other with a common cable, and the monitoring device is a device that can send and receive address signals, transmits the address signal that needs to be monitored to a remote monitoring target location, and decodes the address signal sent by the monitoring target location device. When it matches with your own address, on the contrary, the contents of the monitoring target are sent as a signal to the remote monitoring device, and the remote monitoring device receives the signal and decodes and recognizes the monitoring target and its contents. Split-type monitoring technology is currently the most commonly used method.

[Problems to be Solved by the Invention] The above-mentioned method of communicating the content signal of the monitoring target with the monitoring device at the remote place by arranging the address recognition device on both sides has been used as a reliable method since ancient times. However, the communication method is also defined, and it is famous as RS232C. However, this method is generally used in order to avoid bad reading due to signal deterioration because it is not suitable for high-speed communication because the deterioration of the signal on the signal transmission cable increases when the communication speed is increased and it is not suitable for long-distance communication. The maximum distance is 20 m. There is also an example in which an expensive optical cable is used for further long-distance communication, and a signal converter for this purpose is mutually used between the monitoring target and the monitoring device. Of course R
Although it has been put into practical use under a standard different from S232C, it requires more dedicated equipment, resulting in higher cost. In addition, a converter or the like is also required for connection with general RS232C devices, which have many users, and there are many cost problems. Therefore, the problem to be solved by the present invention is to provide an apparatus capable of reducing the total facility cost, ensuring a recognition speed capable of responding to a change in the state of a monitoring target, and extending the transmission distance without using an optical cable. It is in.

[Means for Solving the Problem] Therefore, for the purpose of solving this problem, the present invention achieves cost reduction by eliminating the address recognizing device for each monitored object which is usually provided, and reception of the monitoring device. By supplying a power supply for the detector from multiple parts to the signal detectors to be monitored at multiple points with a common cable, transmitting the signal of the detector to the receiving part with the same cable, and selecting the signal at the receiving part. The purpose of the present invention is to provide a system that can reduce the cost and further extend the practical transmission distance as compared with the RS232C which is a normal communication method.

[Operation] A method of preparing an address recognition device for monitoring, which is generally used as described in the prior art, and communicates with a signal recognition device of a monitoring device provided in a remote place. In contrast, multiple addressees constantly send status signals to the receiver of the monitoring device, and the receiver of the monitoring device selects the required signal of the target of monitoring, thereby eliminating the need for an address recognition device on the target of monitoring. became. The signal from the monitored object may be an intermittent signal of a fixed RS232C for a fixed time, but may be a simple ON or OFF continuous signal, an analog signal, or a voice signal. It is a feature of the present invention that there is also an advantage that high-speed transmission can be achieved because there is less.

[Embodiment] FIG. 1 shows an example of a signal collecting method of a plurality of detectors of the present invention, which will be described. First of all, it is how to transmit the signal from the detector to be monitored to the receiving part of the monitoring device, but if the distance is 100 meters or more, the method by air transmission by radio wave can be simply and effectively used. However, in this case, a separate antenna is required for the detector, and the electric power of radio waves is also required to improve noise resistance, and the number of frequencies that can be used differs depending on the purpose of use, output of radio waves used, radio wave format used, etc. Very few and may require a national license. Therefore, radio waves can be used as long as the number of monitoring targets is within a predetermined number of frequencies, but the present invention adopts a method of transmitting via a common wire in order to support more monitoring targets. I'll explain. Reference numeral 1 is a coaxial cable, which is economically constructed by using it as both a signal for outputting the signals of the two sensors to be monitored from the three detectors and a power supply to the three detectors. I can. The sensor of No. 2 is the ON or OF that converts the state of the monitored object into a switch signal
Although it may be an F signal, anything can be used as long as it can be converted into an electric signal such as temperature, humidity, pressure, flow rate, liquid level, analysis value, illuminance, and volume in the example of changing the physical state into an analog voltage signal and monitoring the state. . Then, the electric signal is converted into a high frequency signal by the detector of 3. Next, the detectors of 3 are sequentially connected to the other detectors by the coaxial cable of 1 in a squeezing manner, and are led to the receiving unit described later by the coaxial cable. And 3 detectors are 2
The sensor detects the state of the object to be monitored, and the signal is used to modulate a high-frequency signal oscillated at a different frequency for each detector. Details of this portion will be described later with reference to FIGS. FIG.
Is an example of processing the signals of the detector of the present invention collected by the receiving unit, and the overall system of the present invention will be described with reference to FIGS. 1 and 2. Reference numeral 5 is a personal computer (abbreviation of personal computer). Controlling the entire system under the command of the processing of the invention, 8 is configured to display results and the like on a CRT (cathode ray tube, also known as cathode ray tube display device, hereinafter referred to as CRT). As the personal computer and the 8 CRT, general commercial products can be used. 6
Is a cable switch and is configured as a high-frequency relay and used as necessary when there are many detectors. The purpose is to connect three detectors to one coaxial cable, but all In some cases, it may be more economical to wire in groups for each location rather than in a potato-like manner, and because the frequency assigned to each detector in 3 is finite, there are tens of channels described below. Because of the fact that the transmission impedance of 1 coaxial cable is low because it is divided into groups, it is not possible to connect 3 detectors indefinitely to the cable for a short distance (about 100 meters) and the like. Prepare a coaxial cable and use it when it corresponds to a large number of 3 detectors, such as when switching with the cable switching device of 6 according to the instruction of the personal computer of 5 and selectively connecting to the receiving unit of 7. Continuing with this example, the cable switch 6 is connected to the input / output interface (hereinafter referred to as I / O) of the personal computer 5 and, if there are plural cables according to the instructions programmed by the personal computer 5, the plural switches 1 Configure so that one of the coaxial cables can be selectively connected. Next, the signal of the coaxial cable 1 selected by the cable changer 6 is input to the receiver 7
The receiving unit of 7 and the personal computer of 5 are connected by I / O.
The contents of the signal of the designated frequency are sequentially output to the personal computer of 5 by sequentially instructing from the program of the personal computer of. It is also effective to connect a terminating resistor having the same impedance as that of the coaxial cable at the leading end of the monitored side of the coaxial cable 1 to reduce unnecessary radiation of radio waves. The details of the receiving unit 7 will be described later. Next, the details of the detector 3 will be described. FIG. 3 shows an example of converting the voltage of the detector signal of the present invention into a frequency and modulating the oscillation signal. Is a method suitable when it can be converted into a voltage signal. Reference numeral 4 in the drawing is a detection circuit for converting the state change received by the sensor 2 into a voltage signal. In the case of temperature and pressure, a resistance bridge circuit is generally used, and its output is amplified to a voltage of several volts. . This output is input to 14 voltage / frequency converters and converted into a proportional frequency. These 14 voltage / frequency converters can be easily configured with transistors, but commercially available semiconductor integrated circuits (hereinafter referred to as ICs)
, Which can be used, for example, model name LM331 of National Semiconductor Inc. in USA or equivalent, and is designed to output a frequency of 5 KHZ with a voltage input of 2.5 V, for example. Next, the oscillation circuit of FIG. 10 is an oscillator composed of a crystal oscillator and a transistor, and the oscillation frequency is changed by changing the crystal oscillator for each of the three detectors. Of course, the oscillation circuit of 10 may be an oscillation circuit using a coil and a capacitor, but since it is necessary to change the frequency for each of a plurality of 3 detectors, it is easier and more accurate to change the frequency with a crystal oscillator. In addition, the oscillation frequency interval at this time is also determined by the selectivity of the receiving unit of 7, but the selectivity is generally economical with a dozen KHZ width, so it is better to separate them as much as possible, in order to avoid interference with adjacent frequencies. Moreover, it is better to separate the frequency intervals by several tens of KHZ. For example, if 100KHZ is separated, if a device having a receiving bandwidth of 7 at 2 MHZ is used, then 20 detectors can be used in one group. That is the reason. These 10 oscillation circuits modulate the oscillation signal at about the audio frequency, but the modulation is amplitude modulation, FM modulation, SSB.
However, in this embodiment, FM modulation will be described. The voltage signal obtained by the sensor of 2 and the detection circuit of 4 is set to 1 with respect to 10 oscillation circuits of the crystal oscillator and the transistor configuration with the FM modulation circuit (a general FM modulation circuit (not shown)).
It is input to the voltage / frequency converter 4 and converted to a low frequency, and is used as the FM modulation input of the oscillation circuit 10. Then, the output of the oscillation circuit 10 passes through 11 buffer amplifiers and is coupled to the coaxial cable 1 by means of 12 coupling capacitors. The size of these 12 coupling capacitors is several PF
The degree is good, and the impedance used when the frequency used is 27 MHZ, for example, is several K ohms, and the impedance of one coaxial cable is usually 50 ohms, so interference with other 3 detectors is reduced, and the output of multiple 3 detectors is reduced. The signal loss due to the reduction of the transmission impedance due to the parallel connection is reduced. The frequency to be used is not limited to the one given as an example, and the attenuation factor of the signal due to the length of the coaxial cable 1 used increases as the frequency used increases. MHZ
The frequency of is economical. Next, the power supply filter of 13 removes the high frequency signal in the coaxial cable by the filter circuit of the coil and the capacitor in order to extract only the DC voltage applied to the coaxial cable of 1, and uses it as the DC voltage for the power supply of the detector of 3. Then, a part is configured to stabilize the voltage with the stabilizing power source 9 and supply it to the detection circuit 4 and the voltage / frequency converter 14 to maintain the accuracy of each circuit. The signal oscillated by this method is normally radiated and transmitted in the air as a radio, but a corresponding output is required. However, since the present invention transmits it in the coaxial cable 1, the high frequency output of the detector 3 is extremely small. A good signal can be transmitted to the receiving part of 7 at least, and the coaxial cable can be used for both signal transmission and power supply, which not only reduces the facility cost but also reduces interference with other devices. In addition, there is also an advantage that the interference of noise from other devices is small. Next, FIG. 4 shows an example in which the oscillation frequency determining element of the multivibrator circuit is used for signal detection of the detector 3 of the present invention. 4 in FIG.
Reference numeral 6 is a multivibrator circuit made of a commercially available IC (semiconductor integrated circuit), for example, model name TC4047 of Toshiba Corporation.
BP or equivalent can be used, and a combination of the 15 frequency determining circuits (combination of resistors and capacitors) and 16 multivibrator circuits oscillates a low frequency signal of about 5 KHZ. For example, the resistance portion is used for the sensor of 17. For this, a resistance element (CdS) whose resistance changes with brightness, a resistance element for humidity detection made of a multi-hard ceramic, or the like can be used. Then, the low-frequency signal generated here modulates the high-frequency signal oscillated by the ten oscillation circuits described above with reference to FIG. The stabilized power supply, the buffer amplifier 11 and the power supply filter 13 shown in FIG. 9 are the same as those described in FIG. 3, and the output of this detector is a small 12 coupling capacitors.
It is connected to the coaxial cable of and transmitted to the receiving section of 7. Next, FIG. 5 shows details of an example of a receiving unit for selectively receiving signals from a plurality of detectors of the present invention. Reference numeral 20 is a high-frequency amplifier that amplifies the signal from the coaxial cable selected by the cable switcher 6 if necessary. Reference numeral 21 is a frequency mixing circuit, which is mixed with the frequency generated by the PLL oscillation circuit 30 and the difference between them is calculated. Converts a signal to a frequency. 3
The PLL of the PLL oscillation circuit of 0 is an abbreviation for a phase-locked loop circuit, and a commercially available IC can be used for this circuit, for example, MC145163 or the equivalent under the model name of Motorola, Inc. in the United States. Reference numeral 29 is a frequency division ratio setting circuit, and 2 is the content received from the personal computer of 5 through the communication interface of 32 by the communication IC with address 31.
The division ratio latched by the latch and buffer circuit of 8 is 3
Set to 0 PLL oscillation circuit to oscillate the specified frequency. As an example, if the oscillation frequency of a certain detector coupled to one coaxial cable is 27 MHZ, then 30
The oscillating frequency from the PLL oscillating circuit is 37.7 MHZ, and is converted to 10.7 MHZ by the 21 frequency mixing circuit and input to the 22 FM-IF IC. As the 22 FM-IF IC, a commercially available IC can be used, for example, MC3359 or an equivalent product under the model name of Motorola, USA. The signal FM-demodulated by the FM-IF IC of 22 is amplified by the low frequency amplifier of 23, further made into a rectangular wave through the waveform shaping circuit of 24, and created by the counting time generation circuit of 26 through the counter gate circuit of 25. The gate of 25 counter gate circuit is opened only for 1 second, and it is configured to count with the frequency counter of 27. The program of the personal computer of 5 gives an instruction of their progress, and after counting, the count value of the frequency counter of 27 becomes 28. The configuration is such that programming is performed so as to be read by a personal computer (5) through a communication IC with an address (31) and a communication interface (32) via the latch and buffer circuit. The above circuits are not shown but may be general ones, can be easily made by using commercially available transistors and ICs, and in order to receive the oscillation frequency of each of the three detectors, 30 PLL oscillation circuits are required. It suffices to give the division ratio for the oscillation frequency to the 5 division ratio setting circuit of 29.
It is only necessary to sequentially specify from the personal computer of the above with the series of flows already explained. With the above configuration, the signals obtained by each of the 3 detectors are converted into low frequency signals and added to the high frequency signals, and at the 7 receiving section. The frequency that is received and demodulated is obtained as a count value by the frequency counter of 27, and is fed back to the personal computer of 5. Therefore, the frequency vs. voltage of each of the three detector signals determined in advance by the personal computer of 5 is determined. By converting, the signal values corresponding to the original two sensors can be obtained. Although the description goes back and forth, 31 communication ICs with addresses are ICs that can exchange commands and data with the 5 PC by connecting to the 5 PC with the RS232C standard. This is also a commercially available IC, for example, MC144 under the model name of Motorola, Inc.
69 or equivalent can be used. Then, the configuration is such that instructions and results can be displayed with the personal computer 5 via the 28 communication interfaces. Needless to say, these parts can be configured by a commercially available one-chip microcomputer IC or the like. Also, the conversion value of the signal of 3 detectors for each reception frequency programmed by the personal computer of 5 on the CRT of 8 is sequentially displayed, and recorded for each frequency of the detector received in the memory area of the personal computer of 5. Go or prepare an upper and lower limit alarm value for each reception frequency in a separate memory area in advance and compare it with this value, and if it exceeds the value, display it on the CRT 8 as an alarm for the detector of that reception frequency. It is also possible to program in the personal computer of 5 so that the above may be repeated. Therefore, even if there are a plurality of 3 detectors, it is possible to construct a system capable of management and determination. As a matter of course, it is programmed in the personal computer of 5 so as to process the data of the received detector data in real time or to process the data such as graph from the recorded data and display it on the CRT of 8. That is also an effective method. FIG. 6 shows an example of the flow of programs between the personal computer and the receiver.

[Advantages of the Invention] There are many needs for collecting data of a plurality of monitored objects at distant places, and as described in the prior art, an address recognition device is prepared for the monitored objects on the site and sent by a pair of cables. An address response method is widely used in which the monitoring information is sent back via another pair of cables when one's address can be confirmed. For this reason, the equipment cost is increased because the address recognition response device is required for each of the detectors to be monitored, and if the status signal is an analog value, it is converted from an analog value to a digital value and interfaced with the address recognition response device. Not only is it costly, but the system is electrically large and a dedicated power supply is required for each detector. Therefore, I hear that there are many departments that cannot make a decision to implement it because the facility cost is high. However, according to the present invention, the output signal of the detector in which a status signal is changed to a low-frequency signal and a simple high-frequency oscillator is modulated is connected to another detector by a common coaxial cable in a potato-like manner as a monitoring target in the field. Since the address recognition response device is unnecessary, the device cost of the device of the present invention can be significantly reduced at the location to be monitored, and a detector can be easily added. Therefore, it is considered to be an effective means for both general and industrial use.

[Brief description of the drawings]

FIG. 1 shows an example of signal acquisition of multiple detectors of the present invention.

FIG. 2 shows an example of processing a collected detector signal of the present invention in a receiver.

FIG. 3 is a block diagram of an example of a detector for converting the voltage of the detector signal into a frequency and modulating the oscillation signal of the present invention.

FIG. 4 is a block diagram of an example of a detector using an oscillation frequency determining element of a multivibrator circuit for detecting a signal of the detector of the present invention.

FIG. 5 shows an example of a block diagram of a receiving unit that selectively receives signals from a plurality of detectors of the present invention.

FIG. 6 shows an example of a program flow of a display unit (personal computer) of a signal recognition result of the present invention.

[Description of sign]

1 Coaxial Cable 20 High Frequency Amplifier 2 Sensor 21 Frequency Mixing Circuit 3 Detector 22 FM-IF I
C 4 Detection circuit 23 Low-frequency amplifier 5 Personal computer 24 Waveform shaping circuit 6 Cable switcher 25 Counter gate circuit 7 Receiver 26 Counting time generation circuit 8 CRT 27 Frequency counter 9 Stabilizing power supply 28 Latch and buffer circuit 10 Oscillation circuit 29 Dividing Ratio setting circuit 11 Buffer amplifier 30 PLL oscillation circuit 12 Coupling capacitor 31 Communication IC with address 13 Power supply filter 32 Communication interface 14 Voltage / frequency converter 15 Frequency determination circuit 16 Multivibrator circuit 17 Sensor resistance

Claims (3)

[Claims] 1. A device for transmitting a signal from a signal detector to be monitored at a plurality of points to a common receiving unit and sequentially selecting and recognizing the signal, wherein the signal of the detector is set to an audible frequency for each signal detector. A means for converting and a means for oscillating at a frequency determined in advance for each detector, means for modulating the oscillation signal of the transmitter with a detector signal converted to an audible frequency, and a signal for transmitting and modulating each detector To a common transmission means, a means for selectively receiving the signal transmitted from the common transmission means at a frequency determined for each detector, a means for demodulating an audible frequency from the received signal, and the demodulated A signal selection and recognition device for sequentially recognizing signals of a plurality of detectors, comprising means for counting audible frequencies and means for reproducing signal values of the detector from the counted values. 2. The means according to claim 1, wherein the means for converting the detector signal into an audible frequency for modulation has a means for converting the frequency into a frequency proportional to the voltage of the detector signal for use as a modulation input of the oscillator. A signal selection and recognition device for sequentially recognizing signals from a plurality of detectors. 3. The frequency proportional to the state signal according to claim 1, wherein the oscillation frequency determining element of the multivibrator circuit is used as the state detecting element of the detector as a means for converting the detector signal into an audible frequency and modulating it. A signal selecting and recognizing device for sequentially recognizing signals of a plurality of detectors, which are used as means for converting the signals into a modulation input of an oscillating unit.