JPH0648797B2 - Automatic line selection method - Google Patents

Description

DETAILED DESCRIPTION [Outline] In the automatic line selection method, transmission from a slave station is performed by a relay station B.
When the transmission from the slave station is received directly by the master station A at the same time as being received by the master station A and received by the master station A, an incoming signal delayed corresponding to the incoming electric field sent from the relay station B to the parent station, The master station determines the time difference from the incoming signal delayed in response to the incoming electric field at the master station, and automatically selects the line corresponding to the incoming signal with the smaller delay amount. Communication between the master station A and the slave station C can be performed using a line with a good ratio.

[Industrial application field]

The present invention relates to an automatic channel selection system used in a simplex mobile radio system including a master station A, a movable slave station C, and a relay station B, for example.

FIG. 7 shows a mobile radio system diagram.

In the figure, the relay station B is provided to expand the service area of the master station A and has a service area as shown by the dotted line on the left side, but the service areas of both stations overlap in the shaded area. Part.

Therefore, when the slave station C enters the shaded area, the master station A receives the direct wave from the slave station C and the relay wave from the relay station B at the same time, so the signal-to-noise ratio (hereinafter referred to as S / N) The operator may select the line with the better (omitted) and communicate.

The frequencies used are, as shown in FIG. 7, a master station A-slave station C,
It is assumed that frequency 1 is used between the relay station B and the slave station C, and frequency 2 is used between the master station A and the relay station B in the simplex system.

[Conventional technology]

 FIG. 8 is a block diagram of a conventional example.

In FIG. 8, a mobile station C (not shown) that can move is shown in FIG.
When it is in the shaded area in the figure, the receiving part (RX-A) of the radio 1 of the master station A
When the radio wave is directly received from the slave station C (not shown), the squelch gate indicating that the radio wave has been received is in an open state, and the output indicator SQG turns on a reception indicator lamp (not shown). On the other hand, the radio wave of the slave station C relayed by the relay station B (not shown) is received by the reception unit (RX) of the wireless device 2 and is displayed by another reception display lamp similar to the above.

Then, the operator of the master station A knows that the radio wave of the slave station C has been received through both lines, and drives the relay 13 by the switch 14 to output the signal (SPK-A or SPK) to the speaker.
Drive 15 and select the line with the better S / N.

After that, the antenna is transmitted by the signal (STT-A or PTT) that turns on the press talk switch 17 using that line (TX-A
Or TX) and use the microphone 16 to send a signal (MIC-A or MI
C) is sent to slave station C and communication is started, but the line is often not switched until the call ends.

[Problems to be solved by the invention]

However, since the slave station C moves, the incoming level of the master station A or the relay station B fluctuates, and the line selected at the start of the call does not always maintain a good S / N until the end of the call. Therefore, there is a problem in that calls are not always performed using the line with the better S / N.

[Means for solving problems]

According to the present invention, the above-mentioned problem is caused by the present invention in a simplex type mobile radio system including a master station, a movable slave station, and a relay station that relays radio waves of the master station and the slave station. Electric field detector (41) that detects the electric field each time it is transmitted from the slave station
And an incoming signal generator (42) that generates an incoming signal delayed corresponding to the output of the electric field detector, and the master station has the same electric field detector (11) and incoming signal generator as the relay station. (12) is provided, and the time difference between the output of the incoming signal generator of the relay station and the master station is determined, and the line between the master station and the slave station is connected directly to the master station and the slave station every time the slave station transmits. It is equipped with a selection circuit that selects between stations or between a master station and a slave station via a relay station, and a line corresponding to an incoming signal with a small delay is automatically selected for each transmission from the slave station. It is solved by the characteristic automatic line selection method.

[Action]

According to the present invention, when the master station A receives the radio wave from the slave station C directly and via the relay station B, the incoming electric field detected by the electric field detector 41 of the relay station B is added to the incoming signal generator 42. From the incoming signal with the delay amount corresponding to the incoming electric field, the incoming signal detected by the electric field detector 11 in the master station A to the incoming signal generator 12, and from here the incoming signal with the delay amount corresponding to the incoming electric field. The time difference judgment unit 61 judges the time difference, and the selector 62 automatically selects the line corresponding to the incoming signal with a small delay amount.

Since this selection is made every time the slave station C transmits, the communication between the master station A and the slave station C is always performed by using the line having a good S / N.

〔Example〕

2 is a block diagram of an embodiment of the present invention, FIG. 3 is a block diagram of an incoming signal generator in FIG. 2, FIG. 4 is an operation explanatory diagram of FIG. 3, and FIG. Block diagram of the selection circuit of
FIG. 6 shows the operation explanatory view of FIG.

In addition, the same symbol indicates the same object throughout the drawings, and
The numbers on the left side of FIGS. 6 and 6 show the waveforms of the same numbers in FIGS. 3 and 5.

First, the operation of FIG. 2 will be described.

(1) When one station receives the radio wave from the slave station C When only the master station A receives the radio wave (frequency 1) from the slave station C When the master station A receives the radio unit 1 (RX-A) When received by
The demodulated signal SPK drives the speaker 15 via the selection circuit 6.

When only the relay station B receives and relays to the master station A, the signal AF extracted by demodulating the radio wave of the slave station C by the reception unit (RX-B) of the radio station 4 of the relay station B is transmitted to the radio device 5. The signal is transmitted to the master station A at frequency 2 via the unit (TX).

In the master station A, this signal (SPK) is received by the receiving unit (RX) of the wireless device 2.
The speaker 15 is taken out and the speaker 15 is driven through the selection circuit 6.

When transmitting from the master station A to the slave station C, the signal (PTT) generated by pressing the press talk switch 17 normally switches the antenna connected to the receiving section to the transmitting section (TX-A or TX), and the microphone The signal MIC from 16 is transmitted to the slave station C directly or via the relay station B. That is, the transmission line is performed using the reception line described above.

(2) When two stations receive radio waves from slave station C The radio section 4 of relay station B receives the radio waves from slave station C (RX-B)
When the signal is received at step S1 and is equal to or higher than the predetermined incoming level Vth, the squelch gate (SQG) is opened, and the output corresponding to the incoming electric field from the electric field detector 41 is added to the incoming signal generator 42. Therefore, as will be described later, the incoming signal generator 42 generates an incoming signal whose rising edge is delayed in response to the incoming electric field, and turns on the transmitting unit (TX) of the wireless device 5 with this signal (PTT), and the master station A The point B when the squelch gate (SQG) of the receiver (RX) of the wireless device 2 is opened is added to the selection circuit 6.

On the other hand, in the master station A, the incoming signal A having the delay amount corresponding to the incoming electric field is added to the selecting circuit 6 described later, similarly to the case of the relay station B, and the line of the incoming signal having the small delay amount is selected.

Since the point B is the sum of the delay amount of the incoming signal generator 42 and the delay amount of the relay line, the fixed delay circuit 13 of the master station A is for canceling the delay amount of this relay line. is there.

Next, referring to FIGS. 3 and 4, the incoming signal generator (12, 42)
The operation of will be described.

In FIG. 3, the (−) terminal of the comparator 421 is connected to the power supply Vcc via the resistor R1 and grounded via the capacitor C.

Then, as shown in FIG. 4-a, the incoming electric field E is changed to the resistor R3.
When applied between Vcc and Vcc, the squelch SQG relay (not shown) is turned on as shown in Fig. 4b, and the potential of the (-) terminal of the comparator 421 is shown as shown in Fig. 4b. Rises to (V
When the value of (cc-E) is exceeded, the output as shown in Fig. 4 is obtained.

The incoming electric field E and delay time T (transient characteristics of R1 and C and E
As shown in FIG. 4C, the higher the incoming electric field E, the shorter the delay time T becomes.

Further, R2 is for protecting the output of the comparator 421 to 0 when the squeegee gate is off, and R3 is for protection when short-circuited by SQG-2.

Next, a block diagram of the selection circuit 6 is shown in FIG. 5 and an operation explanatory diagram is shown in FIG. 6. On the left side of FIG. 6, the S / N of the line from the master station A to the slave station C is the relay station B. If it is better than passing, the right side shows the opposite case.

First, when the incoming signal of the master station A is input to the time difference determination unit 61 first, the monostable multivibrator 6 is transmitted via the OR circuit 611.
Flip-flop driven by 15 (hereinafter abbreviated as FF)
When 614 is reset, the output of NAND circuit 613 is
In the "L" state, the output of the FF 614 is held in the "H" state, and the relay 621 selects the master station A side.

With this method, the S / S
The line that is good for judging N is automatically selected.

〔The invention's effect〕

As described in detail above, it is always possible to automatically select the line with the better S / N for communication.

[Brief description of drawings]

 FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is a block diagram of an incoming signal generator in FIG. 2, and FIG. 4 is an operation of FIG. Explanatory diagram, FIG. 5 is a block diagram of the selection circuit in FIG. 2, FIG. 6 is an operational explanatory diagram of FIG. 5, FIG. 7 is a mobile radio system diagram, and FIG. 8 is a block diagram of a conventional example. . In the figure, 11 and 41 are electric field detectors, 12 and 42 are incoming signal generators, and 6 is a selection circuit.

Claims (1)

[Claims] 1. In a simplex mobile radio system comprising a master station, a movable slave station, and a relay station that relays the radio waves of the master station and the slave station, a relay station receives an incoming electric field from the slave station. An electric field detector (41) that detects each transmission from the station, and an incoming signal generator (42) that generates an incoming signal delayed corresponding to the output of the electric field detector are provided, and the master station is a relay station. With the electric field detector (11) and the incoming signal generator (12) of the same configuration,
The time difference between the output of the incoming signal generator of the relay station and the master station is judged, and the line between the master station and the slave station is directly connected between the master station and the slave station every time the slave station transmits, or via the relay station. An automatic line selection method, which is equipped with a selection circuit that selects between a master station and a slave station, and automatically selects a line corresponding to an incoming signal with a small delay every transmission from the slave station.