JPS61283259A - Signal transmission system - Google Patents

Abstract

PURPOSE:To improve the reliability of a radio system by using a frequency in the opposite order to that for the modulation of one word information quantity sent before so as to modulate the information quantity of one word to be sent next. CONSTITUTION:In modulating one word of information quantity with different two frequencies fH, fL alternately, when the one word information quantity sent before is modulated in the order of the frequencies fH and fL, the one work of information quantity sent next is modulated in the order of the frequency fL and the frequency fH. The procedure above is applied at every transmission of one work or plural words. Thus, in sending the information of plural words, even when either frequency receives disturbance, since the modulation frequency differs from one or plural words on information quantity, it is possible to receive accurate information.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a frequency shift keying signal transmission system in which the amount of information of one word is modulated alternately by two different frequencies and transmitted.

[Conventional technology]

FIG. 2 is a schematic diagram showing a frequency shift keying wireless system. In the figure, 1 is an emergency transmitter, 2 is a fire detection transmitter, 3 is a receiver, and 4 is a siren for external communication.

In addition, Figure 3 shows the format of the amount of information in one word output from the emergency transmitter. In the figure, 5 is a synchronization bit, 6 is a house code, 7 is a data code, 8 is a parity bit, and 9 is a stop bit. Bit 10 is one word.

Figure 4 is an example of a format for transmitting the amount of information of one word using the conventional frequency shift keying method.
, f and shows the order of alternating modulation.

5 shows a receiver block of the radio system in FIG. 2, in which 31 is an antenna, 32 is a filter with frequency fH, 33 is a filter with frequency fL,
4 is a comparator, 35 is a microcomputer, 36
indicates a house code setting switch; 3a, 3b, and 3d indicate notification lamps; 3c indicates a buzzer; and 4 indicates an external communication siren.

Next, the operation of the wireless system configured as described above will be explained.

When a fire occurs, the fire detection transmitter 2 operates, and the fire detection transmitter 2 outputs a synchronization pulse 5. The amount of information of 4 words (1 word) consisting of a house code of 6, a data code of fire occurrence of 7, a parity of 8, and a stop bit of 9 is transmitted continuously. House code 6 is 8 bits and can cover 256 houses, and data code 7 is 4 bits and can transmit 16 types of information such as alarms. Parity bit 8 is set to either "1" or "0" so that the number of data "1"s is an even number. In addition, when an emergency situation such as an injury occurs, by pressing the button on the emergency transmitter 1, the synchronized pulse 5 can be activated in the same way as the fire detection transmitter 2.
．． House code 6, data code 7 indicating an emergency has occurred.
, a parity of 8, and a stop bit of 9. The information amount of one word is continuously transmitted for four words.

The receiver 3 receives the above signal with an antenna 31, demodulates it into a pulse signal with an fH filter 32 and an fL filter 33, inputs it to a microcomputer 35, decodes it, compares it with the house code of the receiver 3 itself, and converts the data into a pulse signal. After determining the type and performing a parity check, the notification lamp 3
a, 3b.

3d and sounds the buzzer 3c. Further, an external communication siren 4 is sounded to notify neighboring households.

[Problem that the invention seeks to solve]

The transmission and reception of conventional frequency shift keying wireless systems is configured as described above, so if interference occurs at one of the two frequencies, the demodulated waveform may be distorted or the signal-to-noise ratio may be reduced. There was a problem in that the reliability of the system deteriorated due to deterioration of the signal, making it impossible to receive data.

[Means for solving problems]

Therefore, in the frequency shift keying signal transmission system according to the present invention, when the amount of information of one word sent previously is modulated by alternating and repeating at two frequencies with different values, the amount of information of one word sent next is modulated. The method is characterized in that the information amount of one word transmitted previously is modulated at frequencies in the opposite order.

[Effect]

The amount of information of l word is expressed as two frequencies f, , fL with different values.
When modulating alternately, if the information amount of one word sent previously is modulated in the order of frequency fH2 frequency fL,
The modulation of the amount of information in the next sent word is frequency f and frequency r
Modulate in the order of H. This is done every time one word or multiple words are transmitted. As a result, when transmitting multiple words of information, even if there is interference on one of the frequencies, it is possible to receive accurate information because the modulated frequency is different for each word or multiple words of information. .

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows that during one transmission of 4 consecutive words, 2 times the amount of information for each word.
This is an example in which two shift keying frequencies fH and fL are exchanged. In this case, if the ■th word is modulated in the order of fL and fH, the second word is modulated in the order of fH and fL, and such exchange is performed every time one word is transmitted.

That is, as in the conventional example, when the fire detection transmitter 2 or the emergency transmitter L operates, the house code and data code are pulsed and transmitted, but two shift keying frequencies fH and fL are used for each word. Replace and send. If there is no interference on the radio wave transmission path, the receiver can demodulate the signal as before.

If, for example, frequency fH of the two shift keying frequencies is disturbed due to some kind of interference, frequency fLO can be sufficiently determined on the receiver side, but frequency fH becomes unstable. Therefore, the LOW level part of BI PHASE is determined, but the HIGH level part becomes unstable. However, when the second word is received, the frequency fH is still unstable due to interference, but the frequency fH of the second word corresponds to the frequency fL of the first word, and l
Word frequency fL part (BI PHASE LO
The second word frequency fL, which corresponds to the W part), is sufficiently demodulated and discriminated because there is no interference. That is, the part to which fH corresponds in the first word corresponds to stable fL in the second word, and can be determined in the second word. Therefore, by monitoring two words, more reliable signal transmission using the frequency shift keying method becomes possible.

In the above embodiment, an example of a system for wireless transmission is shown, but the transmission medium is radio waves or infrared rays.

Similar effects can be obtained using ultrasonic waves, light, and ordinary electric wires, and although a pulse method has been shown as a frequency shift keying method, other methods such as start-stop synchronization can also produce the same effects as in the above embodiment. . Further, in the above embodiment, the frequency is switched every time one word is transmitted, but the same effect can be achieved even if the frequency is switched every time a plurality of words are transmitted.

〔Effect of the invention〕

As explained above, in the signal transmission method according to the present invention, the amount of information of one previously sent word can be divided into two with different values.
1 to be sent next when modulating alternately and repeatedly at two frequencies
Since the modulation of the information amount of the word was configured to be performed at a frequency in the opposite order to the modulation of the information amount of the l word sent previously, interference may occur on one of the frequencies, causing the demodulated waveform to change. Even if the signal is distorted or the signal-to-noise ratio deteriorates, reception is possible, improving the reliability of the wireless system.

[Brief explanation of drawings]

Fig. 1 is a signal timing diagram showing a signal transmission method according to an embodiment of the present invention, Fig. 2 is an example of a wireless system using a conventional signal transmission method, and Fig. 3 is a conventional transmission output of the amount of information of one word. FIG. 4 is a format example of a conventional frequency shift keying method, and FIG. 5 is a receiver block diagram of the system in FIG. 1...Fire detection transmitter, 2...Emergency transmitter, 3.
...Receiver, 4...External siren, 31...Antenna, 36...House code setting switch. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa (and 2 others) Figure 1 Figure 2

Claims (1)

[Claims] In a frequency shift keying signal transmission system, the information content of one word consisting of multiple bits of information is modulated alternately at two different frequencies, and the modulated information content of one word is transmitted and received in multiple words. Alternatively, a signal transmission method characterized in that, each time a plurality of words of information are transmitted, one word of information is modulated at a frequency in the opposite order to that of the previously transmitted one word of information.