JPH03201193A - Radio type alarm system - Google Patents

Abstract

PURPOSE:To reduce the generation of radio interference due to the simultaneous transmission of the same channel from plural slaves by reading out different delay time values from a numerical sequence in a information table by different counter values at the time of simultaneously detecting abnormal states and setting up two delay time levels. CONSTITUTION:When an alarm is generated from a fire alarm 10, a starting circuit 30 is driven to turn on a power supply control circuit 32 and a CPU 24 executes its operation. A delay time setting part 20 reads out the count output of a delay time setting counter 16, reads out the numerical sequence of false random delay time in the information table 18 based upon the count output and sets up the delay time to be used at the time of sensing a carrier. Thereby, the counting state of the counter is changed in each slave, and even at the time of simultaneously detecting abnormal states, different positions in the numerical sequence of delay time stored in the table 18 are accessed by using the different count values as instruction parameters and respective delay time value are set up in the two levels of the counter count values and the numerical sequence. Consequently, the probability of radio interference due to the simultaneous transmission of plural slaves using the same channel can be remarkably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wireless alarm system for monitoring abnormalities such as fire.

[Conventional technology] Conventionally, in order to monitor fires at construction sites such as buildings, a slave unit with a fire detector directly attached externally was installed on the ceiling side of a warning area, and when a fire signal was received from the fire detector, A wireless alarm system has been proposed in which an abnormality detection signal is wirelessly transmitted to the main picture to notify of an abnormality. Furthermore, the pre-trial has a built-in battery power supply and can be freely installed in any desired location.

In such a wireless alarm system, for example, six frequency channels are assigned to the pre-trial, and when an abnormality is detected, carrier sensing is performed with the pre-trial in the receiving state, and an empty channel that is not used by other pre-trials is selected. Next, the preliminary examination is switched to the transmission state, and an abnormality detection signal is transmitted to the main picture using the empty channel selected by carrier sense. The abnormality detection signal from the preliminary hearing is transmitted continuously, for example, with a transmission period of 8 seconds and a pause period of 2 seconds, for example, while the fire signal is being obtained.

On the other hand, in the main picture, the same six frequency channels as the preliminary trial are assigned, and carrier sensing is always performed on the six channels in sequence.When a carrier is detected, the reception status of the detection channel is fixed and an abnormality from the preliminary trial is detected. Receives detection signals and issues an alarm for abnormal conditions.

By the way, in such a wireless alarm system,
For example, if an abnormality is detected at the same time by two pre-screening devices, carrier sense will select the same channel as an empty channel and transmit the abnormality detection signal, and the main image will be treated as invalid data due to interference caused by simultaneous transmission, causing the abnormality to occur. It becomes impossible to receive detection signals.

Therefore, by setting a different delay time for each slave device and selecting an empty channel for transmission using carrier sense over the unique delay time, it is possible to avoid simultaneous transmission of abnormality detection signals even if abnormality detection is performed at the same time. That's what I do.

[Problems to be Solved by the Invention] However, in such conventional wireless alarm systems, carrier sense is performed by randomly setting different delay times for each slave device, but the number of preliminary hearings is If the number increases, the probability of simultaneous transmission using the same channel increases, and it is desirable to reduce simultaneous transmission from multiple slave devices using the same channel as much as possible.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a wireless alarm system that sets a delay time so as to minimize simultaneous transmission from multiple slave devices.

[Means for solving the problem 1 To achieve this object, the present invention is configured as follows. In addition, the reference numerals of the drawings of the embodiments are also indicated.

First, the present invention allocates a predetermined number (for example, 6) of frequency channels CHI to CH6 to a plurality of trial hearings 12-1 to 12-n to which detectors 10 for detecting abnormalities such as fire are connected, and detects any abnormality. In some cases, the pre-trial 12 is first put into the receiving state and performs carrier sensing over a set delay time to select an empty channel that is used by another pre-trial, then the pre-trial 12 is switched to the transmitting state and the selected empty channel is selected. The present invention is directed to a wireless alarm system that continuously transmits an abnormality detection signal to the master picture 14 by repeating a fixed transmission period and a rest period to warn of an abnormal state.

In the present invention, for such a wireless alarm system, a counter 16 that constantly repeats clock counting; an information table 18 that stores a pseudo-randomized numerical sequence of delay times; A delay time setting means 20 is provided for reading the count value of 16 and sequentially setting the delay time from the numerical value series of the information table 18 using the read count value as an instruction parameter.

Further, the delay time setting means 20 reads and sets the next delay time from the information table every time the second and subsequent transmissions occur.

[Operation] According to the wireless alarm system of the present invention having such a configuration, since the counting state of the counter is different for each slave device, even if abnormality detection is performed at the same time, different counting values are used as indication parameters. Accessing different positions in the delay time numerical series stored in the information table is performed, and by setting the delay time in two stages, the counter count value and the numerical series,
The probability that multiple pre-trials transmit simultaneously using the same channel can be significantly reduced.

[Embodiment] FIG. 1 is a system configuration diagram showing the overall configuration of the present invention.

In FIG. 1, 12-1.12-2. ...-12
-n is a preliminary hearing, each connected to a fire detector 10, and upon receiving a fire detection signal from the fire detector 10, transmits an abnormality detection signal from the antenna 22 toward the main picture 14.

A predetermined number of frequency channels, for example, six frequency channels CHI to CH6 in the 429 MHz band, are assigned to each of the preliminary hearings 12-1 to 12-n. Preliminary hearing 12-1
In the transmission operation of ~12-n, when an abnormality is detected, in order to check whether the channel frequency to be transmitted is being used by another pretrial, the transmitter first enters the receiving state and performs carrier sense over the set delay time. After confirming that it has not been used in another trial by Career Sense,
Next, switch to the transmitting state, and use the selected free channel to continuously transmit the abnormality detection signal to the main picture 14 while the fire detection signal is obtained by repeating a fixed transmission period of 8 seconds and a pause period of 2 seconds. Send to.

FIG. 2 is an embodiment configuration diagram showing an embodiment of the preliminary trial of the present invention.

In FIG. 2, reference numeral 24 denotes a CPU, which has a transmission control section 26, an information table 18 for setting a delay time, and a delay time setting section 20 using a program control function.

28 is a fire receiving circuit to which the fire detector 10 is connected;
When the fire detector IO issues an alarm, the alarm signal is received via the power supply/signal line 100, and the fire reception signal is output to the CPU 24 and the starting circuit 30. When the startup circuit 30 receives the fire reception output, it turns on the power supply control circuit 32, supplies the power supply voltage from the battery power supply 25 to the CPU 24, starts the power-on start, and causes the transmission control unit 26 to transmit the fire detection signal. .

Reference numeral 36 denotes a periodic notification circuit, which uses a timer to output periodic notifications to the CPU 24 and startup circuit 30 once every nine hours, for example, and causes the periodic notification transmission operation to be performed when the power supply control circuit 32 is turned on and the power of the CPt 124 is started.

Furthermore, for the CPt 124, an address setting circuit 34,
A nonvolatile memory 35 is connected. Address setting circuit 34
sets a group address (lower) for one group consisting of one master unit and a plurality of pre-trial units, and an individual address that is set individually for each child unit. The nonvolatile memory 35 is, for example, EEPRO.
M is used and the first transmitted call identification signal (ID code) approved by the Minister of Posts and Telecommunications is stored. Specified low power radio stations under the Radio Law are required to send a call identification signal at the beginning of transmission. Further, the nonvolatile memory 35 stores an extended group address (upper order) in order to provide expandability to the group address.

Furthermore, in the present invention, the CPU 24 is provided with a delay time setting counter 16 used for setting the delay time. The delay time setting counter 16 is constantly supplied with power by the battery power source 25, and counts by a clock, for example, once every 2 seconds.
The counting operation of the clock generated twice is repeated sequentially,
Specifically, a counter circuit that produces a binary 3-bit count output is used.

FIG. 3 is an embodiment configuration diagram showing in more detail the circuit section for setting the delay time of the preliminary hearing in the embodiment of FIG. 2.

In FIG. 3, an information table 18 provided in the CPU 24 stores a pseudo-randomized numerical value series of delay times as shown. In this example, the delay time numerical sequence is 0.2 seconds for address 000, 0.0 seconds for address 001, . . . 0.8 seconds for address 111.
Stores seconds. The delay time setting counter 16 counts the clocks and outputs a binary 3-bit output (b2 bl bO
), and this counter output is given to the delay time setting section 20 in the CPU 24. The delay time setting unit 20 outputs the 3-bit output (b2
bl bO), performs a read access using this counter output as an instruction parameter for the address of the information table 18, reads the delay time of the address position corresponding to the numerical series counter output, and determines the delay time used for carrier detection at that time. Set as time.

Further, the delay time setting section 20 includes a delay time setting counter 16.
After setting the delay time from the information table 18 based on the output of
If the carrier sense of the next channel is started while the channel is in use, the next delay time from the information table 18 is read out and set.

Referring again to FIG. 2, a transmitting/receiving circuit section is provided on the left side of the CPU 24.

In this transmitting/receiving circuit section, 40 is a synthesizer circuit, a PLL circuit 42 and a VCO (voltage controlled oscillator) 44 constitute a PLL oscillation circuit, and the oscillation output of the VCO 44 is outputted via an amplifier 46. The oscillation frequency of the VCO 44 can be freely changed by setting frequency division ratio data from the CPU 24 to the PLL circuit 42. For this reason, the CPU 24 performs 1. Frequency division ratio data is set so as to oscillate the local oscillation frequency necessary for the carrier sense reception operation of the channel frequency to be transmitted. When an empty channel is selected by carrier sensing, frequency division ratio data is set so as to oscillate the carrier frequency of the next selected empty channel.

The output of the synthesizer circuit 40 is applied via a signal switch 48 to a transmitting circuit 50 or a high frequency amplification/mixing circuit 54 on the receiving side. The output of the transmitting circuit 50 is given to the antenna 22 via an antenna switch 52. The other side of the antenna switch 52 is input to a high frequency amplification/mixing circuit 54 . The high frequency amplification/mixing circuit 54 converts the frequency of the received signal using the local oscillation frequency of the channel on which carrier sensing is to be performed, which is output from the synthesizer circuit 40 during carrier sensing, and outputs an intermediate frequency fi signal to the intermediate frequency amplification/mixing circuit 56. do. To explain specifically, for example, the transmission frequency ft1 of channel CHI = 429.175MH
z, and the intermediate frequency from the high frequency amplification/mixing circuit 54 is f1=21.7 MHz, then during carrier sensing of channel CHI, the synthesizer circuit 40 oscillates a local oscillation frequency frl-407,475 MHz and performs high frequency amplification/mixing. Output to circuit 54.

The intermediate frequency amplification/mixing circuit 56 converts the frequency into a 455 KHz intermediate frequency signal using a local oscillator that oscillates at a fixed frequency. In this way, the high frequency amplification/mixing circuit 5
The method in which the frequency is converted twice using the intermediate frequency amplifying/mixing circuit 56 and 4 is known as the double super hetero gain method.

The output of intermediate frequency amplification/mixing circuit 56 is provided to carrier detection circuit 58 and modem 60. The carrier detection circuit 58 discriminates the received signal using a threshold value based on the white noise level when there is no carrier, and provides a detection output of presence or absence of a carrier to the CPU 24.

The MSK modem 60 converts the received frequency signals of 1200 Hz and 1800 Hz into data bits 1 and 0, respectively.
Also, data bit 1.0 from CPU24 is set to 1200H.
It has the function of converting into z and 1800Hz frequency signals,
The frequency signal converted from the data bits by the MSK modem 60 is applied to the VCO 44 of the synthesizer circuit 40 to perform MSK modulation of the carrier frequency.

Reference numeral 62 denotes a power switching circuit, which controls on/off the power supply to the transmitting circuit section and the power supply to the receiving circuit section under the control of the CPU 24. That is, during carrier sensing, the power supply to the receiving circuit section is turned on, and when an empty channel is selected by carrier sensing, the power supply to the receiving circuit section is turned off, and then the power supply to the transmitting circuit section is turned on.

The signal switch 48 and the antenna switch 52 are switched to enable the circuit section side that is in the operating state upon receiving power supply from the power switch circuit 62.

That is, in this embodiment, the receiving mode and the transmitting mode are switched by turning on and off the power supply.

FIG. 4 is a timing chart showing the continuous transmission operation when a fire is detected in the preliminary hearing example of FIG. After switching to and transmitting the fire detection signal to the main picture for a transmission period of 7138 seconds, T2=22 is stopped, and this process is repeated thereafter. During the transmission period of 7138 seconds, the call identification code is first transmitted. This call identification code has a format shown in FIG. When the transmission of the call identification code is completed, the transmission of the mark and transmission code is alternately repeated a plurality of times as shown in FIG. The mark is data in which all 1's are consecutive, while the information code is composed of four frames, frames 1 to 4 shown in FIG. 6, for example.

In FIG. 6, the first start bit 0 and the last stop bit 1 of frames 1 to 4 are provided for frame synchronization. An 8-bit data area is provided following start bit 0, and in frame 1, the group address (
In frame 2, the individual address and group address (lower) are sent, in frame 3, an alarm signal is sent, and in frame 4, a horizontal parity bit is sent.

The horizontal parity bit of frame 4 is set so that the sum of the same bit positions of frames 1 to 3 is, for example, an odd number. Following the 8-bit data area, a parity bit is provided for each frame.

Next, the transmission operation in the preliminary hearing of FIG. 2 will be explained with reference to the operation flow diagram of FIG. 7.

Assuming that the fire detector 10 has triggered an alarm, the startup circuit 30 is activated by the received output from the fire reception circuit 28, turns on the power supply control circuit 32, supplies power to the CPU 24 from the battery power supply 25, and powers the CPU 24. 7th due to on start
The operation flow shown in the figure is executed.

In FIG. 7, first step 81 (hereinafter referred to as "step")
(omitted) performs initialization processing, and the next step 82 reads the call identification code group address (upper), group address (lower), and individual address from the nonvolatile memory 35 and address setting circuit 34. Next, the process advances to 83 to check whether or not continuous transmission is being performed. 8 because it is a continuous transmission when a fire is detected.
Proceed to step 4. On the other hand, at the time of power-on start due to the regular report output from the regular report circuit 36, since continuous transmission is not performed, the process proceeds to 35 and a fixed delay time is set.

In the process 84 in the case of continuous transmission, as shown in FIG.
2 bl bo) is delayed.

The delay time setting unit 20 sets the delay time by accessing and reading out the delay time numerical series in the information table 18 using an address based on the counter output.

Next, the process proceeds to 86, where the local oscillation frequency of the reception channel corresponding to the transmission channel is set in the PLL circuit 42 for carrier sensing. This transmission channel selection is performed in the order of channels CHI to CH6.

Next, in step 87, the power supply to the receiver circuit section is turned on to bring it into operation, and in step S8, it is determined whether or not the power supply has already been turned on to the receiver circuit section, that is, the first power supply to the receiver circuit section after the power-on start. It is checked whether or not there is one, and if it is the first time, the process advances to S9, and after stabilizing the operation of the receiving circuit section in a 300 m5 wait state, the process advances to S10.

In step 810, the presence or absence of carrier detection is checked;
If there is no carrier detection, the process proceeds to 314, waits for the delay time to elapse, and repeats the process of SIo and 814 until the delay time is reached. If it is determined that carrier detection is not performed during the delay time, the process proceeds to 815, and after turning off the receiving circuit section, the division ratio data for oscillating the transmission frequency of the selected channel CHI without a carrier is set in the PLL circuit 42. Then, in step 816, the power to the transmitting circuit section is turned on to bring it into operation.

It then transmits the call identification code first at 817 and then at 818
The mark and transmission code are sent sequentially.

When the transmission is completed, the transmission count counter A is incremented at 819, and it is checked at S20 whether or not transmission has been performed A=n times, for example, n=75 times.When the transmission of marks and data for 75 times is completed, the timer is activated at 821. After a pause of 2 seconds, the process advances to S22 to check whether a fire signal is being received. If a fire signal is being received, the process returns to S2 and the same transmission operation is repeated. On the other hand, if the fire signal has been cut off, the process advances to S23 and a power-off process is performed to cut off the power supply to the CPU 24.

On the other hand, if a carrier is detected in the carrier detection in S10, the process proceeds to S11 to check whether the carrier detection continues for a predetermined time or longer, and if the carrier detection continues for a predetermined time or longer, the process proceeds to S12. Then, the PLL circuit 4 is activated for carrier sensing of the next reception channel CH2.
2, the frequency division ratio data for oscillating the local oscillation frequency of channel CH2 is set, and the process returns to S8 to enter carrier sensing processing for the next channel CH2, and repeat carrier sensing by channel switching until an empty channel is found.

FIG. 8 shows that the fire detector of the pre-trial 12-1 issues an alarm at time t1 and starts transmitting, and then at time t3, the fire detector of the pre-trial 12-1
2-2. A timing chart is shown when the sensors 12-3 simultaneously issue alarms and start transmitting operations.

First, in the preliminary trial 12-1, the power-on start of the CPU 24 is started by the sensor alarm at time t1, and the count output of the delay time setting counter 16 at this time t1 causes
For example, assume that address A=OOO is specified and delay time ΔT1 is set.

Therefore, the carrier sense is set delay time Δ from time t2.
In this case, since channel CH1 is not used by another pretrial, channel CHI is selected as an empty channel, and after a delay time ΔT1 has elapsed, a transmission operation is performed over a transmission period of 8 seconds.

On the other hand, in the preliminary hearing 12-2.12-3, the same time t3
The sensor issues an alarm and the CPU 24 starts powering on. However, the counting state of the delay time setting counter 16 provided in the preliminary hearing 12-2 and 12-3 is random because the initial power-on time is different for each, and for example, the counting output of the preliminary hearing 12-2 provides information. Address A=001 of the table 18 is set and the delay time ΔT2 is read out, and in the preliminary hearing 12-3, the count output of the delay time setting counter 16 is used to set the address A=001 of the information table 18.
01 is specified and the delay time ΔT3 is set. Channel CH from time t4 based on such set delay time
Regarding the carrier sense of I, channel CHI has already been used in the preliminary hearing 12-1, so the preliminary hearing 12-2.12
-3, the switch is made to the carrier sense of the next channel CH2. Here, if it is assumed that the delay setting time on the child device 12-2 side ends early for channel CH2, channel CH2 is selected as an empty channel in preliminary examination 12-2 and a transmission operation begins. At this time, the pretrial 12-3 shifts to carrier sensing of the next channel CH3 in order to detect the carrier of channel CH2. Since the channel CH3 is not used by any pretrial, the pretrial 12-3 starts the transmission operation after the delay time ΔT3.

For the second and subsequent transmissions after a two-second pause, carrier sensing is not performed from channel CHI, but carrier sensing is started from the previously selected channel, and the transmission operation is started. Of course, for the second and subsequent times, carrier sensing from channel CHI may be performed again.

FIG. 9 shows a timing chart in the case where different delay times are set for the pre-trials 12-1 and 12-2, but the end timings of the set times coincide and simultaneous transmission is performed on the same channel.

That is, in the preliminary hearing 12-1.12-2, the sensor alarm time was t.
Although different from l and t2, due to delay times ΔT1 and ΔT5,
If the carrier sense delay time end timings happen to coincide at time t3, both channels select channel CHI as an empty channel and perform a transmission operation. In this case, data is not processed as invalid on the main picture side because of simultaneous transmission in the first transmission operation. In the second transmission after a 2-second pause, the start timing of carrier sense always matches, as shown at time t4.
If the delay times are different, as shown in the figure, for example, carrier sensing over the delay time on the side of the slave device 12-1 is completed first, channel CH1 is selected as an empty channel, data is effectively transmitted, and the slave device 12-2 side is channel C
Since carrier sense of HI can be obtained, channel CH
By performing the carrier sense of 2 and selecting it as an empty channel, it is possible to perform a transmission operation as valid data.

In the transmission operation shown in FIG. 7, even when switching to the carrier sense of the next reception channel in S12, the delay time is changed to the delay time next to the first read delay time in the information table 18 in S13. Although the delay time is switched, the delay time may not be switched.

In addition, in the above embodiment, the case where a fire detector is connected to the preliminary hearing is taken as an example, but in addition to this, an appropriate abnormality detector such as a gas leak detector or an intruder detector may be connected. You may also do so.

[Effects of the Invention] As explained above, according to the present invention, since the counting state of the counter for setting the delay time is different for each preliminary hearing,
Even if abnormality detection is performed at the same time, the delay times at different positions in the delay time numerical series stored in the information table are read out using different counter count values as instruction parameters, and the delay time is read out in two stages: the counter count value and the numerical series. By setting a long delay time, it is possible to significantly reduce the probability of interference caused by multiple pre-trials transmitting simultaneously using the same channel.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram of the present invention; FIG. 2 is a configuration diagram of a preliminary embodiment of the present invention; FIG. 3 is a configuration diagram of an embodiment of the delay time setting circuit section of the present invention; Preliminary transmission timing chart; 5th
The figure is a format configuration diagram of a call identification code transmitted from the reserve of the present invention; Figure 6 is a format configuration diagram of a transmission code transmitted from the reserve of the present invention; Figure 7 is an operation showing the preliminary hearing transmission operation of the present invention It is a flow diagram. FIGS. 8 and 9 are timing charts showing specific examples of transmission operations based on delay time settings of the present invention. In the figure, 10: Fire detector 12.12-1 to 12-n: Reserve 14: Goodwill 162M extension time setting counter 18: Information table 20: Delay time setting section 22: Antenna 24: CPU 25: Battery power supply 26 : Transmission control unit 28 : Fire reception circuit circuit 30 : Start-up circuit 32 : Power supply control circuit 34 Near address setting circuit 35 : Non-volatile memory (!EFROM) 36 : Periodic notification circuit 40 : Synthesizer circuit 42 : PLL circuit 44 : VCO 46 : Amplifier 48: Signal switch 50: Transmission circuit 52: Antenna switch 54: High frequency amplification/mixing circuit 56: Intermediate frequency amplification/mixing circuit 58: Carrier detection circuit 60: MSK modem 62: Power supply switching circuit

Claims (1)

[Claims] 1. A predetermined number of frequency channels are assigned to each of a plurality of slave devices connected to a sensor for detecting an abnormality such as a fire, and when an abnormality is detected in any slave device, the reception state is first set and a set delay time is reached. Performs carrier sense over time to select an empty channel that is not used by other slave devices, then switches the slave device to transmit mode and uses the selected empty channel by repeating a certain transmission period and rest period. In a wireless alarm system that continuously sends abnormality detection signals to the main unit to alert abnormal conditions, there is a counter that constantly repeats the counting operation of the clock; and a pseudo-randomized numerical sequence of delay times is stored. and a delay time setting that reads the count value of the counter at the time of abnormality detection, extracts the delay time from the numerical series of the table information using the read count value as an instruction parameter, and sets the delay time to be used at the time of carrier sensing. A wireless alarm system comprising means and; 2. The wireless alarm system according to claim 1, wherein the delay time setting means extracts and sets the next delay time from the information table for each subsequent transmission of continuous transmission.