JPS6328544B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention receives a carrier wave that is sequentially modulated by a plurality of modulated frequency signals for predetermined durations, and represents information by a sequential combination of the modulated frequencies. The present invention relates to a reception method that can be suitably implemented. In receiving such a carrier wave, it is necessary to sequentially detect the modulated frequency signal obtained after demodulating the carrier wave for each duration. If the duration of the modulated frequency signal changes due to noise or the like, an erroneous detection occurs at the detection time of the modulated frequency signal. It is an object of the present invention to provide a receiving scheme capable of accurately detecting multiple sequential modulated frequency signals. FIG. 1 is a block diagram of one embodiment of the present invention. From the transmitter 1, a carrier wave modulated by the modulation frequency signals p1 to p6 shown in FIG. 2 is sent out. This carrier wave is received and demodulated by the front end circuit 3 of the receiver 2, amplified by the amplifier circuit 4, and commonly applied to filters 5-8. Outputs from filters 5 to 8 are provided to processing circuit 9. The signal derived from the amplifier circuit 4 has the waveform shown in FIG. Although the durations W1 to W6 of the modulated frequency signals p1 to p6 are equal during normal times, different phenomena may occur during abnormal times such as during noise reception. These modulation frequency signals p1 to p6
Among them, the first and last modulation frequency signals P1, P6
is used to control the load 10 provided in the receiver 2. The remaining first plurality (four in this example) of modulated frequency signals p2-p5 are used to identify and address one of the receiver or receivers 2. These modulation frequency signals p1 to p6 have frequencies 1 to 1 shown in Table 1.
It has 4.

[Table] Filters 5 to 8 receive modulation frequency signals p1 to p6.
have cut-off frequencies corresponding to frequencies 1 to 4, respectively. For example, when a modulation frequency signal p1 having a frequency of 1 is derived from the amplifier circuit 4, the filter 5 having a cutoff frequency of 1 passes the modulation frequency signal p1, and the remaining filters 6 to 8 pass the modulation frequency signal p1. Don't pass. The processing circuit 9 sequentially detects the modulated frequency signals p1 to p6 a second plurality (three in this embodiment) of each duration period W1 to W6. The corresponding frequency detection times for each duration period W1 to W6 are as shown in FIG. 2, FIG. 2, and FIG. 2, respectively. For example, during the duration W1 of the modulated frequency signal p1 having a frequency of 1, the processing circuit 9 operates at successive times t1a, t1b, t1, as shown in FIGS. 2-4, respectively.
In c, frequency detection is performed. Similarly, the processing circuit 9 performs frequency detection at sequential times t2a, t2b, and t2c during the duration W2. Similar frequency detection is performed during other duration periods W3 to W6. The shift register 11 receives the output from the processing circuit 9 and stores the detection results of the corresponding frequency detection times for each duration period W1 to W6. A setting circuit 12 such as a pin board is provided to set an address for specifying the receiver 2. The output from the setting circuit 12 is given to the address input circuit 13 and stored in the memory 14. In this way, in the memory 14, a signal representing an address specifying the receiver 2 is stored as a modulated frequency signal p2.
- It is stored corresponding to p5. Table 2 shows the contents stored in the shift register 11 at the frequency detection time shown in FIG.

[Table] In this second table, each time t1a, t2a,...,
The frequency detected at t6a is indicated by a circle in the corresponding column. At time t3a,
It is assumed that frequency 2 was mistakenly detected when frequency 3 should have been detected due to the adverse effect of noise. From the shift register 11, each time t1a, t
Modulation frequencies 1 to 4 at 2a, ..., t6a
A signal representing . The memory 14 outputs data to the receiver 2 at times t2a to t5a in synchronization with the output from the shift register 11.
A signal is derived representing an address specifying the . Each time t1b, t2b,... shown in FIG.
At t6b, the frequency of the modulation frequency signal is detected, whereby the shift register 11 provides the detection results shown in Table 3 to the comparison circuit 15.

[Table] Time t1c, t2c,..., shown in Figure 2 4
Also at t6c, it is assumed that the processing circuit 9 detects the modulation frequency signals p1 to p6, and the detection results are obtained as shown in Table 3. A comparator circuit 15 compares the output from the shift register 11 and the output from the memory 14 corresponding to the modulated frequency signals p2-p5 addressing the receiver 2, and compares the output from the memory 14 with the output from the memory 14 for each duration W2-W5. The combination of detection results at the time indicated by and the memory 14
The output is compared with a predetermined combination output derived from
6. Similarly, the comparison circuit 15 compares the combination of detection results at the times shown in FIG. 2 and another combination of detection results at the times shown in FIG. Compare each combination.
The second shift register derived from these shift registers 11
Combination of multiple (3 in this example) and memory 1
As a result of comparison with a predetermined combination derived from 4, the number of times there is a match is stored in the counter 16. When the count value of the counter 16 is equal to or greater than a predetermined value equal to or lower than the second plurality, the output circuit 17 transmits modulated frequency signals p2 to p5 corresponding to a predetermined combination derived from the memory 14 to the receiver. 2 is identified as being addressed, thereby placing the load 10 in an operating state corresponding to the modulated frequency signals p1, p6. Receiver 2
The count value of the counter 16 which is identified as having been addressed, ie the predetermined value below the second plurality, may be, for example, two. Second
Even if the frequency is erroneously detected as shown in Table 2 at times t1a to t6a in FIG.
As shown in Table 3 in c, if frequency detection is performed correctly twice or more, the receiver 2 is identified as having been specified, and the load 10 is controlled. In this way, even if the detection results shown in Table 2 are obtained at the times shown in FIG. 2, the receiver 2 will not malfunction. As described above, according to the present invention, detection of a first plurality of modulated frequency signals lasting for each predetermined period is sequentially performed a second plurality of times during each duration period, and corresponding detection results for each duration period are performed. A second plurality of combinations are compared with an individually predetermined combination, and when the number of times the comparison results in a match is equal to or greater than a predetermined value equal to or less than the second plurality, the predetermined combination is transmitted. Since the identification is made as follows, erroneous detection due to noise in the modulated frequency signal can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is a diagram for explaining the operation. DESCRIPTION OF SYMBOLS 1... Transmitter, 2... Receiver, 3... Front-end circuit, 4... Amplifying circuit, 5-8... Filter, 9... Processing circuit, 10... Load, 11... Shift register, 1
2...Setting circuit, 13...Address input circuit, 14...
Memory, 15... Comparison circuit, 16... Counter, 17
...Output circuit.

Claims (1)

[Claims] 1. A reception method for receiving sequential combinations of a first plurality of modulated frequency signals lasting for each predetermined period, comprising detecting a second plurality of modulated frequency signals during each of the duration periods. sequentially compare a second plurality of combinations of corresponding detection results for each duration period with a predetermined combination, and as a result of the comparison, the number of times of matching is equal to or less than a predetermined value of the second plurality; When the above is the case, the reception method is characterized in that the predetermined combination is identified as having been transmitted.