JPH04273798A - Radio communication system - Google Patents

Abstract

PURPOSE:To attain system constitution with one carrier by discriminating a signal according to the difference in the tone frequency of the tone squelch even when the carrier is the same. CONSTITUTION:A carrier is one wave of f1 through the whole system and by using tone frequencies F1 and F2 mutually different as the tone squelch tone frequency, a signal is discriminated. When a transmitter 11 is modulated by a transmitting signal, the tone squelch modulation is performed with a tone frequency F1 and transmission is performed. Further, in a receiver 12, the electric wave of the frequency F1 is received, only the tone squelch in which the tone frequency F1 is detected by a tone squelch detecting circuit 14 passes through a gate circuit 15 and becomes the receiving output. Observing stations 31 and 32 are also constituted in the same way, and the tone frequency becomes not F1 but F2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system such as a telemeter system or a telecontrol system that performs remote measurement or remote control using a wireless line.

0002

2. Description of the Related Art First, the present invention will be described with respect to a telemeter system. Figure 5 shows the configuration of a telemeter system without a relay station, where 1 is a monitoring station (master station), 31, 32
are observation stations (child stations). Since the observation station is given the right to transmit only when it is invited by the monitoring station to transmit, even if only one wave of carrier frequency f1 is used, there will be no confusion caused by simultaneous transmission from multiple stations.

FIG. 6 shows the configuration of a telemeter system when a relay station 2 is present. In this case, the relay station receives a radio wave with a carrier frequency f1 from the monitoring station, converts the frequency to f2, increases the power, and sends it to the observation station 32, and also receives a radio wave with a carrier frequency f2 from the observation station 32. , converts the frequency to f1, increases the power, and sends it to the monitoring station 1.

[0004] In this case, by setting f2=f1 and providing a buffer memory in the relay station, it is possible to prevent a plurality of stations, ie, the monitoring station 1, the relay station 2, and each of the observation stations 31 and 32, from transmitting at the same time. However, even with this method, observation station 3
The radio waves of frequency f1 being received by the monitoring station 2 are radio waves transmitted from the relay station 2 and should be received at the observation station 32, or are they radio waves that directly arrived from the monitoring station 1 to the observation station 32 and are the radio waves being received by the observation station 32? 32, it is not possible to discriminate whether the radio wave is one that should not be received or not.

[0005]Also, although the timing of transmission signals such as control signals and response signals may have meaning, there is a difference in timing between signals arriving at an observation station from a relay station and signals arriving directly from a monitoring station. , there is a disadvantage that it is not possible to discriminate between the two signals.

[0006]

[Problems to be Solved by the Invention] The problem to be solved is that when a relay station exists in a conventional wireless communication system, two types of carrier waves f1 and f2 are required as shown in FIG. This puts us at a disadvantage when it comes to allocation. It is an object of the present invention to solve this problem and to enable a system configuration using a single carrier wave.

[0007]

[Means for Solving the Problems] The main feature of the present invention is that the tone squelch technique is used to discriminate signals based on the difference in tone frequency of the tone squelch even if the carrier waves are the same.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the present invention, in which the same reference numerals as in FIGS. 5 and 6 indicate the same or corresponding parts, and the carrier wave is one wave f1 throughout the entire system.
Different tone frequencies F1 and F2 are used as tone frequencies of tone squelch to discriminate signals. FIG. 2 is a block diagram showing an example of the configuration of the monitoring station 1 in FIG.
is a gate circuit.

When modulating the transmitter 11 with a transmission signal, tone squelch modulation is performed at the tone frequency F1 and the signal is transmitted. The transmitting antenna and receiving antenna are shown in Figure 1.
Although one antenna is shared as shown in FIG. 2, two antennas are shown in FIG. 2 for convenience of explanation. The receiver 12 receives radio waves with a frequency f1, but only those whose tone frequency F1 is detected by the tone squelch detection circuit 14 pass through the gate circuit 15 and become a reception output. Note that the configurations of the observation stations 31 and 32 shown in FIG. 1 are also similar to the configuration shown in FIG. 2. However, the tone frequency is F2 instead of F1.

FIG. 3 is a block diagram showing an example of the configuration of the relay station in FIG. 1. In the figure, 20 is a transmitter, 21 is an analog-to-digital converter (hereinafter abbreviated as A/D), 22 is a buffer memory, 23 is a digital-analog converter (hereinafter abbreviated as D/A), 24 is a transmitter, 25 is a relay control circuit, 26 is a tone squelch detection circuit for tone frequency F1, 27 is a tone squelch detection circuit for tone frequency F2, and 28 is a tone squelch detection circuit for tone frequency F2. A tone squelch oscillation circuit 29 has a tone frequency F1, and a tone squelch oscillation circuit 29 has a tone frequency F2.

The receiver 20 receives the frequency f1 from the monitoring station 1.
radio waves and radio waves of frequency f1 from each observation station arrive. The output of the receiver 20 is converted into a digital signal by the A/D 21 and temporarily stored in the buffer memory 22. Further, depending on which of the tone squelch detection circuits 26 and 27 has an output, it is determined whether the radio waves being received are from the monitoring station 1 or from the observation stations 31 and 32. Relay station 2
is given the right to transmit for relaying immediately after the reception is completed, and converts the contents of the buffer memory 22 into an analog signal using the D/A 23, modulates the signal using the transmitter 24, and transmits the signal. In this case, if the signal stored in the buffer memory 22 is sent at tone squelch frequency F1, it is relayed with tone squelch frequency F2 superimposed on it, and if it is sent at tone squelch frequency F2, The tone squelch oscillation circuit 29 or 28 is controlled so as to superimpose and transmit the tone squelch frequency F1.

FIG. 4 is an operation time chart showing an embodiment of the present invention, and the horizontal axis shows the passage of time. During t0-t1, the monitoring station 1 sends out a call signal to the observation station 31. Since this tone frequency is F1, the receiver output at this time is not valid at any observation station. The relay station 2 receives this, stores the output of the receiver 20 in the buffer memory 22, and simultaneously stores in the relay control circuit 25 that there is an output to the tone squelch detection circuit 26.

[0013] When the transmission of the monitoring station 1 ends at point t1, the relay station 2 has obtained the right to transmit, modulates the transmitter 24 with the contents of the buffer memory 22, and transmits (period t1-t2). . Since the tone frequency when this signal was received by relay station 2 was F1, the tone frequency when relaying this signal was F2.

Observation stations 31 and 32 both receive this signal, and both receive outputs are valid, but observation station 32 does not perform any processing because the signal has an address that does not match its own address. Since the signal is addressed to the observation station 31, the observation station 31 waits for the relay station to complete transmission and sends out the response signal between t2 and t3. The tone frequency of tone squelch at this time is F2
Therefore, the monitoring station 1 has no reception output, and the signal is input to the buffer memory 22 at the relay station 2.

When the observation station 31 finishes transmitting at time t3, the relay station 2 sends out the contents of the buffer memory 22. The tone frequency at this time is F1, and in the monitoring station 1, the output of the receiver 12 passes through the gate circuit 15 and becomes an effective reception output. Communication similar to that for the observation station 31 is performed with respect to the observation station 32 during the period t4-t8.

In the embodiment shown in FIG. 3, the buffer memory 22 is used for signal delay in the relay station 2, but the present invention can be similarly implemented using a conventionally known signal delay circuit other than the buffer memory.

[0017]

[Effects of the Invention] As explained above, the wireless communication system of the present invention can use a single radio frequency even when a relay station exists, and since the signal is simply delayed and relayed as is, the transmission It has the advantage that it can be relayed regardless of the code, etc., and that it can also relay voice signals for telephone calls.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of the monitoring station shown in FIG. 1;

FIG. 3 is a block diagram showing a configuration example of the relay station shown in FIG. 1;

FIG. 4 is a time chart showing the operation of an embodiment of the present invention.

FIG. 5 is a block diagram showing the configuration of a telemeter system without a relay station.

FIG. 6 is a block diagram showing a conventional system.

[Explanation of symbols]

1 Monitoring station 2 Relay station 26 Tone squelch detection circuit (F1) 27 Tone squelch detection circuit (F2) 28 Tone squelch oscillation circuit (F1) 29 Tone squelch oscillation circuit (F2)
)31,32 Observation station

Claims (1)

[Claims] Claim 1: In a wireless communication system in which one master station performs wireless communication with one or more slave stations via a relay station, and transmission from each slave station is performed only by invitation from the master station, the above-mentioned A transmitter, which is installed in the master station, modulates a carrier wave of frequency f1 with a transmission signal, performs tone squelch modulation with a signal of tone frequency F1, and transmits the signal; means for validating the received output only during the period in which the tone squelch signal of frequency F1 is included, provided in each slave station;
A transmitter that modulates a carrier wave of frequency f1 with a transmission signal and performs tone squelch modulation with a signal of tone frequency F2, which is a frequency different from F1, and transmits the signal, and is provided in each of the slave stations and receives radio waves of frequency f1. Means for validating the reception output only during the period when the radio wave includes a tone squelch signal of tone frequency F2, provided in the relay station, receiving the radio wave of frequency f1, storing it in a buffer memory, and adding a tone to the radio wave. When a tone squelch signal of frequency F1 is included, as soon as the reception of the radio wave is completed, the carrier wave of frequency f1 is modulated according to the contents of the buffer memory, and the signal is tone squelch modulated with the signal of tone frequency F2 and transmitted. When the tone squelch signal of the tone frequency F2 is included, as soon as the reception of the radio wave is completed, the carrier wave of the frequency f1 is modulated by the contents of the buffer memory, and the signal of the tone frequency F1 is tone squelch modulated and transmitted. A wireless communication system characterized by: