JP2840343B2 - Wireless alarm system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wireless alarm system for monitoring an abnormality such as a fire.

[Prior art] Conventionally, in order to monitor a fire at a building site such as a building, a child unit having an externally attached fire detector is installed on the ceiling side of a guard area, and when a fire signal is obtained from the fire detector. A wireless alarm system has been proposed in which an abnormality detection signal is transmitted wirelessly to a parent device to notify an abnormality. Note that the slave unit has a built-in battery power source, and can be freely installed at a required place.

In such a wireless alarm system, for example, six frequency channels are assigned to slave units, and when an abnormality is detected, the slave unit is first set to a reception state to perform carrier sense, and an empty channel not used by another slave unit is detected. Then, the slave is switched to the transmission state, and an abnormality detection signal is transmitted to the master using the empty channel selected by the carrier sense. As for the transmission of the abnormality detection signal from the slave unit, continuous transmission is performed while a fire signal is obtained, for example, repeating a transmission period of 8 seconds and a pause period of 2 seconds.

On the other hand, in the parent device, the same six frequency channels as those of the child device are allocated, and the carrier sense of the six channels is always performed sequentially. Receiving an abnormality detection signal and alarming an abnormal state.

By the way, in such a wireless alarm system, for example, when abnormality is detected simultaneously in two slave units,
The same channel is selected as a vacant channel by carrier sense and an abnormal detection signal is transmitted, and the interference is caused by simultaneous transmission, so that the master unit processes the invalid data and disables reception of the abnormal detection signal.

Therefore, by setting a different delay time for each slave unit and selecting and transmitting an empty channel by carrier sense over a unique delay time, simultaneous transmission of an abnormality detection signal can be avoided even if abnormality detection is performed at the same time. Like that.

[Problems to be Solved by the Invention] However, in such a conventional wireless alarm system, the carrier sense is performed by randomly setting a different delay time for each slave unit. Increases, the probability of simultaneous transmission using the same channel increases, and it is desirable to reduce the simultaneous transmission from a plurality of slaves using the same channel as much as possible.

The present invention has been made in view of such conventional problems, and has as its object to provide a wireless alarm system that sets a delay time so as to minimize simultaneous transmission of a plurality of slaves.

[Means for Solving the Problems] In order to achieve this object, the present invention is configured as follows. The reference numerals of the drawings of the embodiments are also shown.

First, according to the present invention, a predetermined number (for example, 6) of a plurality of slave units 12-1 to 12-n connected to a sensor 10 for detecting an abnormality such as a fire is connected.
Frequency channels CH1 to CH6 are assigned, and when any abnormality is detected, the slave unit 12 is first set to a reception state, carrier sense is performed over a set delay time, and an empty channel not used by another slave unit is selected. Next, the slave unit 12 is switched to the transmission state, and the abnormality detection signal is continuously output by repeating the fixed transmission period and the pause period using the selected empty channel.
It is intended for a wireless alarm system that sends an alarm to an abnormal condition by sending it to 14.

In the present invention, such a wireless alarm system has a counter 16 which constantly counts clocks.
An information table 18 storing a pseudo-randomized numerical sequence of delay times; and reading the count value of the counter 16 when an abnormality is detected, and using the read count value as an instruction parameter to calculate the delay time from the numerical sequence of the information table 18. And a delay time setting means 20 for reading and setting the delay time.

Further, the delay time setting means 20 reads and sets the next delay time in the information table every time the second and subsequent transmissions of the continuous transmission are performed.

[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 unit, even if abnormality detection is performed at the same time, a different counting value is indicated by the instruction parameter. The access is performed at different positions in the numerical sequence of the delay time stored in the information table, and by setting the delay time in two stages of the counter count value and the numerical sequence, a plurality of slaves use the same channel. Thus, the probability of simultaneous transmission can be greatly reduced.

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

In FIG. 1, reference numerals 12-1, 12-2,..., 12-n denote slave units, each of which is connected to a fire detector 10. When a fire detection signal from the fire detector 10 is received, an abnormality is detected. The signal is transmitted from the antenna 22 to the parent device 14.

Each of the slave units 12-1 to 12-n has a predetermined number of frequency channels, for example, six frequency channels CH1 to C in a 429 MHz band.
H6 is assigned. The transmission operation of the slave units 12-1 to 12-n is performed by first setting the reception state to check whether or not the channel frequency to be transmitted is being used by another slave unit when an abnormality is detected. After performing carrier sense over time and confirming that it is not being used by another slave unit by carrier sense, it switches to the transmission state and uses the selected idle channel for a fixed transmission period of 8 seconds and a pause period. While the fire detection signal is obtained by repeating 2 seconds, the abnormality detection signal is continuously transmitted to the parent device 14.

FIG. 2 is an embodiment configuration diagram showing one embodiment of the slave unit of the present invention.

In FIG. 2, reference numeral 24 denotes a CPU which includes a transmission control unit 26, an information table 18 for setting a delay time, and a delay time setting unit 20 by a program control function. Reference numeral 28 denotes a fire receiving circuit to which the fire detector 10 is connected.
When an alarm is issued, an alarm signal is received via the power / signal line 100, and a fire reception signal is output to the CPU 24 and the activation circuit 30. The startup circuit 30 is a power control circuit when it receives a fire reception output.
32 is turned on, the power supply voltage from the battery power supply 25 is supplied to the CPU 24 to start power-on, and the transmission control unit 26 performs a fire detection signal transmission operation.

Reference numeral 36 denotes a periodic notification circuit, which provides a periodic notification output to the CPU 24 and the activation circuit 30 by a timer, for example, once every nine hours, and causes the power supply control circuit 32 to be turned on to start the power transmission of the CPU 24, thereby causing the CPU 24 to transmit the periodic notification.

Further, an address setting circuit 34 and a nonvolatile memory 35 are connected to the CPU 24. The address setting circuit 34 sets a group address (lower order) in which one master unit and a plurality of slave units constitute one group, and an individual address individually set for each slave unit. The non-volatile memory 35 stores, for example, a call identification signal (ID
Code) is stored. In a specific low power radio station according to the Radio Law, it is mandatory to transmit a call identification signal at the beginning of transmission. Further, in the non-volatile memory 35, an extended group address (higher order) is stored in order to make the group address expandable.

Further, in the present invention, the CPU 24 is provided with a delay time setting counter 16 used for setting a delay time. The delay time setting counter 16 constantly receives the power supply from the battery power supply 25, and sequentially repeats a clock counting operation, for example, a clock counting operation generated once every two seconds. Specifically, a binary 3-bit count output is performed. Is used.

FIG. 3 is a block diagram of an embodiment showing in more detail a circuit unit for setting the delay time of the slave unit in the embodiment of FIG.

In FIG. 3, information table 1 provided in CPU 24
Numeral 8 stores a pseudo-randomized numerical sequence of delay times as shown. In this embodiment, the numerical sequence of delay time stores 0.2 seconds at address 000, 0.0 seconds at address 001,..., 0.8 seconds at address 111. The delay time setting counter 16 counts the clock and outputs a binary 3-bit (b2 b1
b0), and this counter output is given to the delay time setting unit 20 in the CPU 24. The delay time setting unit 20 reads the 3-bit output (b2 b1 b0) of the delay time setting counter 16 at the timing when the CPU 24 is powered on by the detection of the fire, and reads the counter output as an instruction parameter for the address of the information table 18 for read access. And reads the delay time at the address position corresponding to the numerical sequence counter output, and sets it as the delay time used for carrier detection at that time.

Further, the delay time setting unit 20 sets the delay time from the information table 18 based on the output of the delay time setting counter 16, performs carrier detection, and shifts to carrier sense of the next channel when the first channel CH1 is in use. If
The next delay time in the information table 18 is read and set.

Referring to FIG. 2 again, a transmission / reception circuit unit is provided on the left side of the CPU 24.

In this transmission / reception circuit section, reference numeral 40 denotes a synthesizer circuit, and a PLL circuit 42 and a VCO (voltage controlled oscillator) 44
An L oscillation circuit is configured to output the oscillation output of the VCO 44 via the amplifier 46. The oscillation frequency of VCO44 is set to CP for PLL circuit 42.
It can be changed freely by the division ratio data set from U24. For this reason, at the time of the first carrier sense, the CPU 24 sets the frequency division ratio data so as to oscillate the local oscillation frequency required for the carrier sense reception operation of the channel frequency to be transmitted. When an empty channel is selected by carrier sense, 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 supplied to a transmission circuit 50 or a high-frequency amplification / mixing circuit 54 on the reception side via a signal switch 48. The output of the transmitting circuit 50 is provided to the antenna 22 via the antenna switch 52. The other of the anthena switch 52 is a high-frequency amplification / mixing circuit 54
Is input to The high frequency amplifying / mixing circuit 54 converts the frequency of the received signal according to the local oscillation frequency of the channel to be subjected to carrier sensing output from the synthesizer circuit 40 during carrier sensing, and outputs the intermediate frequency fi signal to the intermediate frequency amplifying / mixing circuit 56 I do. More specifically, for example, if the transmission frequency ft1 of the channel CH1 is 429.175 MHz and the intermediate frequency from the high frequency amplification / mixing circuit 54 is fi = 21.7 MHz, the synthesizer circuit 40 performs the local oscillation frequency at the time of carrier sensing of the channel CH1. It oscillates fr1 = 407.475 MHz and outputs it to the high frequency amplification / mixing circuit 54.

The intermediate frequency amplifying / mixing circuit 56 converts the frequency to a 455 KHz intermediate frequency signal using a local oscillator that performs fixed frequency oscillation. Such a method of performing frequency conversion twice by the high frequency amplification / mixing circuit 54 and the intermediate frequency amplification / mixing circuit 56 is known as a double superheterodyne method.

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

The MSK modem 60 has a function of converting the received frequency signals of 1200 Hz and 1800 Hz into data bits 1 and 0, respectively, and a function of converting the data bits 1, 0 from the CPU 24 into frequency signals of 1200 Hz and 1800 Hz. The frequency signal converted from the data bit is applied to VCO 44 of synthesizer circuit 40 to perform MSK modulation of the carrier frequency.

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

The signal switch 48 and the antenna switch 52 are provided with a power switch circuit 62.
Is switched so as to make the circuit unit side which has been operated by receiving the power supply from the circuit unit valid. That is, in this embodiment, the reception mode and the transmission mode are switched by turning on and off the power supply.

FIG. 4 is a timing chart showing a continuous transmission operation when a fire is detected in the slave unit embodiment of FIG. 2. When a fire is detected, first, the reception state is entered, an empty channel is selected by carrier sense, and transmission is performed after selection. After switching to the state, the transmission operation of the fire detection signal to the master unit is performed during the transmission period of T1 = 8 seconds, and then the operation is paused for T2 = 2 seconds, and thereafter, this operation is repeated. In the transmission period of T1 = 8 seconds, the call identification code is transmitted first. This call identification code has the format configuration shown in FIG. When the transmission of the call identification code is completed, the transmission of the mark and the transmission code is alternately repeated a plurality of times as shown in FIG. The mark is data in which all 1s are continuous, while the information code is composed of, for example, four frames 1 to 4 shown in FIG.

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 the start bit 0, a group address (upper) is sent in frame 1, an individual address and a group address (lower) are sent in frame 2, and an alarm signal is sent in frame 3. , And in frame 4, horizontal parity bits are sent. The horizontal parity bit of frame 4 is
The parity bits are set so that the sum of the same bit positions of the two is odd, for example. Subsequent to the 8-bit data area, a parity bit for each frame is provided.

Next, the transmission operation in the slave unit of FIG. 2 will be described with reference to the operation flow chart of FIG.

Now, if the fire detector 10 issues an alarm, the fire receiving circuit
The start-up circuit 30 operates by the reception output of 28, and the power supply control circuit
Turn on 32 and supply power to the CPU 24 from the battery power supply 25.
The operation flow of FIG. 7 is executed by the 24 power-on start.

In FIG. 7, first, step S1 (hereinafter, “step”)
Is omitted), the initialization process is performed, and in the next S2, the nonvolatile memory
The call identification code group address (upper), group address (lower) and individual address are read from the address setting circuit 34 and the address 35. Next, the process proceeds to S3, where it is checked whether or not the transmission is continuous. When a fire is detected, the process proceeds to S4 because of continuous transmission.
On the other hand, at the time of power-on start by the periodic notification output from the periodic notification circuit 36, since the transmission is not continuous, S5
And a fixed delay time is set.

In the process of S4 in the case of the continuous transmission, the count output (b2 b1 b1) output from the delay time setting counter 16 at the time of the power-on start of the CPU 24 as shown in FIG.
b0) is read into the delay time setting section 20 and the delay time setting section
20 sets the delay time by accessing and reading the numerical value series of the delay time in the information table 18 with the address based on the counter output.

Next, proceeding to S6, 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 channel CH1
CHCH6.

Next, proceeding to S7, the power supply to the receiving circuit unit is turned on to be in an operation state, and whether or not the power supply to the receiving circuit unit has already been turned on in S8, that is, whether the power supply to the first receiving circuit unit after the power-on start is performed. It is checked whether there is, and if it is the first time, the process proceeds to S9 to wait for 300 ms to stabilize the operation of the receiving circuit unit, and then proceeds to S10.

For S10, check for carrier detection,
If there is no carrier detection, the process proceeds to S14 and waits for the elapse of the delay time, and the processes of S10 and S14 are repeated until the delay time is reached. When it is determined that the carrier detection is not performed for the delay time, the process proceeds to S15, after the receiving circuit unit is turned off, the dividing ratio data oscillating the transmission frequency of the selected channel CH1 without the carrier is sent to the PLL circuit 42. Set, S16
To turn on the power supply to the transmission circuit unit to bring it into an operating state.

Next, the call identification code is transmitted first in S17, and then the mark and the transmission code are transmitted sequentially in S18. When you finish sending
In step S19, the transmission counter A is incremented.
= N times, for example, n = 75 times, check if
When the transmission of the mark and the data over and over is completed, the timer is paused for 2 seconds in S21, and the process proceeds to S22 to check whether or not the fire signal is being received. If the fire signal is being received, the process returns to S2 and repeats the same transmission operation. On the other hand, if the fire signal has been cut off, the process proceeds to S23, where power off processing for cutting off the power supply to the CPU 24 is performed.

On the other hand, in the carrier detection of S10, if a carrier is detected, the process proceeds to S11 to check whether the carrier detection continues for a predetermined time or more, and if the carrier detection has continued for a predetermined time or more, the process proceeds to S12. Advances to the PLL circuit 42 for carrier sense of the next reception channel CH2.
The frequency division ratio data for oscillating the local oscillation frequency of CH2 is set, the process returns to S8, the carrier sensing process for the next channel CH2 is started, and carrier sensing by channel switching is repeated until an empty channel is found.

FIG. 8 shows that the fire detector of the slave 12-1 issues a notification at time t1 and starts a transmission operation, and then at time t3, the two slaves 12-2, 12-2.
12 shows a timing chart in the case where the detectors 12-3 simultaneously emit a notification and start a transmission operation.

First, in the slave unit 12-1, when the sensor is activated at time t1, the CP
It is assumed that the power-on start of U24 is started and, for example, the address A = 000 is designated and the delay time ΔT1 is set by the count output of the delay time setting counter 16 at the time t1. Therefore, carrier sensing is performed for a set delay time ΔT1 from time t2. In this case, since channel CH1 is not used by another slave, channel CH1 is selected as an idle channel and 8 seconds after delay time ΔT1 has elapsed. The transmission operation over the transmission period is performed.

On the other hand, in the slave units 12-2 and 12-3, at the same time t3, the sensor issues an alarm and the CPU 24 starts power-on. However, the counting states of the delay time setting counters 16 provided in the slaves 12-2 and 12-3 are random because the respective initial power-on times are different.
The address A = 001 of the information table 18 is set by the count output, and the delay time ΔT2 is read. In the slave 12-3, the information output is calculated by the count output of the delay time setting counter 16.
The address A = 101 of 18 is designated and the delay time ΔT3 is set. The carrier sense of channel CH1 from time t4 based on such a set delay time has already been
Since the channel CH1 is used at -1, the slave units 12-2,12
In any one of -3, the carrier sense is switched to the next channel CH2. Here, the slave 12 for the channel CH2
If the end of the delay setting time on the -2 side is early,
At 12-2, the channel CH2 is selected as an empty channel, and the transmission operation starts. At this time, channel CH2 is
The process shifts to the carrier sense of the next channel CH3 in order to detect the carrier of. Since the channel CH3 does not use any slave units, the slave unit 12-3 starts the transmission operation after the delay time ΔT3.

For the second and subsequent transmissions after a 2 second pause,
The carrier sensing is started from the previous selected channel without performing the carrier sensing from the channel CH1, and the transmission operation is started. Of course, the second and subsequent times may be performed again from the carrier sense from channel CH1.

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

That is, in the slave units 12-1 and 12-2, the sensor alert time is t1, t2.
However, when the delay times ΔT1 and ΔT5 coincide with each other at the time t3 when the carrier sense delay time ends, the channel CH1 is selected as an empty channel and the transmission operation is performed. In this case, the data is invalidated and not processed on the parent device side for simultaneous transmission for the first transmission operation. Next, in the second transmission after a two-second pause, the start timings of the carrier sense always coincide with each other as shown at time t4. The carrier sense over the delay time on the -1 side ends first and the channel CH
By selecting 1 as an empty channel and transmitting data effectively, the slave unit 12-2 performs carrier sensing on channel CH2 since carrier sense of channel CH1 is obtained, and selects valid channel to obtain valid data. And the transmission operation can be performed.

Incidentally, in the transmission operation of FIG. 7, even when switching to the carrier sense of the next reception channel in S12, the delay time is set to the delay time next to the delay time read first in the information table 18 in 13 Although the switching is performed, the switching of the delay time may not be performed.

Further, in the above embodiment, the case where the fire detector is connected to the slave unit is taken as an example. In addition, an appropriate abnormality detector such as a gas leak detector or an intruder detector is provided. You may make it connect.

[Effects of the Invention] As described above, according to the present invention, since the counting state of the delay time setting counter differs for each slave unit, a different counter count value is indicated even if abnormality detection is performed simultaneously. The delay time at different positions in the numerical sequence of the delay time stored in the information table as a parameter is read out, and a plurality of slaves use the same channel by setting the delay time in two steps of the counter count value and the numerical sequence. It is possible to greatly reduce the probability of interference caused by simultaneous transmission using the signals.

[Brief description of the drawings]

FIG. 1 is a block diagram of a system of the present invention; FIG. 2 is a block diagram of an embodiment of a slave unit of the present invention; FIG. 3 is a block diagram of an embodiment of a delay time setting circuit unit of the present invention; FIG. 5 is a diagram showing a format of a call identification code transmitted from the slave of the present invention; FIG. 6 is a diagram showing a format of a transmission code transmitted from the slave of the present invention; The figure is an operation flowchart showing the slave unit transmission operation of the present invention. 8 and 9 are timing charts showing specific examples of the transmission operation based on the delay time setting of the present invention. In the figure, 10: fire detector 12, 12-1 to 12-n: slave 14: master 16: delay time setting counter 18: information table 20: delay time setting section 22: antenna 24: CPU 25: battery power 26: Transmission control unit 28: Fire receiving circuit circuit 30: Start circuit 32: Power supply control circuit 34: Address setting circuit 35: Non-volatile memory (EEPROM) 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

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G08B 25/10

Claims (2)

(57) [Claims] A predetermined number of frequency channels are assigned to each of a plurality of slave units connected to a detector for detecting an abnormality such as a fire,
When an abnormality is detected in any of the slaves, first, carrier sensing is performed for a set delay time as a reception state to select an idle channel that is not used by another slave, and then the slave is switched to a transmission state to select the idle channel. In a wireless alarm system that continuously sends an abnormality detection signal to the master unit by repeating a fixed transmission period and pause period using a channel to alert an abnormal state, the clock counting operation is constantly repeated. A counter; an information table storing a pseudo-randomized sequence of delay times; reading a count value of the counter when an abnormality is detected; extracting the delay time from the numerical sequence of the table information using the read count value as an instruction parameter; A delay time setting means for setting a delay time to be used at the time of carrier sense. . 2. The wireless alarm according to claim 1, wherein the delay time setting means takes out and sets the next delay time in the information table at each time of the second and subsequent transmissions of the continuous transmission. system.