JPS6345141B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a selective call broadcasting apparatus that transmits a selective call signal and an audio signal from a master station, receives the same at a slave unit, and performs amplified broadcasting.

Generally, in this type of selective call broadcasting equipment,
This is done with a configuration as shown in FIG. In the figure, 1 is a master station (transmitting device), 2 is a transmitting antenna,
3 is a first receiving station (receiving device), 4 is a receiving antenna thereof, 5 is a trumpet speaker thereof, 6 is a second receiving station (receiving device), 7 is a receiving antenna thereof,
8 is the trumpet speaker, 9 is the listener, 1
0 is a mountain as a sound reflector, A is the first direct sound from the first trumpet speaker, B is the second direct sound from the second speaker, and C is the first trumpet speaker. This is the reflected sound from the sound mountain 10.

In the above configuration, when the base station 1 transmits a selective call code for a specific area from the transmitting antenna 2,
first and second receiving stations 3 provided in the same area;
As a result, the listeners 9 in the same area receive two sets of direct sound inputs, and as a result, the audio from the master station 1 is simultaneously emitted from the trumpet speakers 5 and 8. , B and a set of reflected sounds will be heard at the same time,
Moreover, in reality, the two sets of direct sounds or reflected sounds are at different distances from each other to the listener 9, so there is a time lag for transmission, and the respective sounds interfere with each other and become echoes, which has the disadvantage of being extremely difficult to hear. Ta. In this case, a method can be considered to allocate separate selective calling codes to the first and second receiving stations to prevent the two receiving stations from being called at the same time, but this would reduce the calling capacity by half compared to the number of allocated channels of radio waves. There are drawbacks to doing so.

The present invention aims to provide a selective call broadcasting device that eliminates the above-mentioned conventional drawbacks, and one embodiment thereof will be described below with reference to the drawings.

In FIG. 2, A is a diagram showing a signal configuration in a conventional system, B is a diagram showing a signal configuration in another conventional system, and C is a diagram showing a signal configuration in the present invention. 21 consists of a combination of three call codes A, B, C, 23 consists of a combination of three call codes A, D, E, and 21' consists of A, C,
Each one consists of three call signs of B. 22 is an audio signal such as an announcement.

The configuration of FIG. 2 A allows the first, second, and
While two receiving stations are called at the same time, the second
In the system shown in FIG. B, the first receiving station 3 corresponding to the calling code ABC is called the first time, and the second receiving station 6 corresponding to the calling code ADE is called the second time. The case of FIG. 2C is similar to the case of B, but differs only in the structure of the selective call code. That is, B requires different call codes for ABC and ADE, whereas C requires different call codes for ABC and ACB.
Since the second and third codes in the calling code are simply transposed to each other, the receiving station simply installs frequency selection filters with the same configuration in reverse order, and also uses a combination of the same codes. It has the advantage of being easy to use.

FIG. 3 is a diagram showing the configuration of the automatic call code addition device part of the master station 1, in which 51 is a counter circuit, 52 to 55 are count output terminals thereof, and 56
is a reset terminal, 57 is a clock pulse input terminal, 58 to 60 are oscillation circuits that oscillate frequencies corresponding to A, B, and C shown in FIG. 2C, respectively, 61 to 63 are switch circuits, and 64 is a synthesis switch. 65 is an audio signal input terminal, 66 is an output terminal, and 67 is a signal transmission order changing circuit. 68 is a control input terminal to which a reset signal is applied.

Next, the operation of the above embodiment will be explained. In the steady state before calling, an L level input signal is applied to the clock pulse input terminal 57 and the reset terminal 56. Therefore, the counter circuit 51 is turned off,
Therefore, the switch circuits 61 to 63 are
It is OFF. Also, since the input signal of the control input terminal 68 is at L level, the signal sending order changing circuit 67
is turned off, and therefore the count output terminal 53 is connected to the switch circuit 62. Further, the count output terminal 54 is connected to a switch circuit 63.

Now, when a clock pulse is applied to the clock pulse input terminal 57, the oscillation circuits 58-60 each oscillate at a determined frequency. On the other hand, the counter circuit 51 starts counting, and the count output terminal 5
5 becomes H, the switch circuit 64 operates and the announcement audio signal input terminal 6 is sent to the output terminal 66.
5 is disconnected, and switch circuits 61 to 63 are connected. A pulse signal with a constant width is output to the count output terminal 52 N seconds after the counter circuit 51 starts counting. The switch circuit 61 is turned ON by the width of this pulse signal, and the output of the oscillation circuit 58 is obtained at the output terminal 66. Further, after N seconds, a pulse signal is outputted to the count output terminal 53, and this pulse signal turns on the switch circuit 62 since the signal sending order changing circuit 67 is off. The output of the oscillation circuit B59 is obtained at the output terminal 66. Furthermore, after N seconds, a pulse signal is outputted to the count output terminal 54, the switch circuit 63 is turned on, and the output of the oscillation circuit 60 is obtained at the output terminal 66. In this way, a selective calling code for the receiving station indicated by numeral 21 in FIG. 2C is transmitted. In FIG. 3, when the counter circuit 51 finishes counting, the count output terminal 55 becomes L level and the switch circuit 6
4 returns to the inactive state, and the announcement audio signal input terminal 65 is connected to the output terminal 66. Since the output terminal 66 is thus connected to the modulation input terminal of the radio, the announcement audio signal is applied to the radio as a modulation signal via the switch circuit 64.

When the first receiving station 3 in FIG. 1 finishes broadcasting, a reset signal is automatically or manually applied to the reset terminal 56 and control input terminal 68 in FIG. 3 to reset the counter circuit 5.

When the reset signal is applied to the control input terminal 68, the signal sending order changing circuit 67 operates, and the count output terminal 53 changes to the signal sending order changing circuit 6.
It is connected to the switch circuit 63 via 7. Further, the count output terminal 54 is connected to the signal sending order changing circuit 67.
It is connected to the switch circuit 62 via. A signal is input to the reset terminal 56, and the counter circuit 51
is reset, and the counter circuit 51 starts counting again. When counting starts, the count output terminal 55 becomes H, the switch circuit 64 operates, the announcement audio signal input terminal 65 is disconnected from the output terminal 66, and the switch circuits 61 to 63 are connected. A pulse signal is output to the count output terminal 52 N seconds after the counter circuit 51 starts counting. This pulse signal is the switch circuit 6
1 is turned on and the oscillation circuit 58 is output to the output terminal 66. Furthermore, after N seconds, a pulse signal is output to the count output 2 terminal 53, and the signal order sending circuit 67 is activated.
Since it is ON, the output of the oscillation circuit 60 is obtained via the signal sequential sending circuit 67 to the output terminal 66 where the switch circuit 63 is turned ON. Further, after N seconds, a pulse signal is outputted to the count output terminal 54, and the switch circuit 62 is turned on via the signal order sending circuit 67.
The oscillation circuit 59 is output to the output terminal 66. In this way, a selective calling code is sent out to the receiving station designated by numeral 21 in FIG. 2C. When the count ends, the count output 4 terminal 55 of the counter circuit 51 in FIG. In this way, it becomes possible to make an announcement to the receiving station corresponding to code 21.

As explained above with reference to the embodiments, according to the present invention, in a public address broadcasting system, it is possible to ensure clear broadcasting that prevents inter-speaker interference sound, and also adopts a method of changing the order of signal transmission in the selective calling method. Therefore, there is no need to reduce the conventional call capacity. It is effective and has great industrial value.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a general selective call broadcasting device, FIG. 2 is an explanatory diagram showing the configuration of the selection signal,
FIG. 3 is a block diagram showing the structure of the automatic call code addition device portion of the parent station of the selective call broadcasting apparatus according to an embodiment of the present invention. 1... Master station, 3... First receiving station, 6... Second
receiving station.

Claims (1)

[Claims] 1 Consisting of a master station, a plurality of receiving stations installed within the same reception area to receive signals transmitted from the master station, and loudspeakers installed at each of the receiving stations, The selective calling code constituting the transmission signal is composed of a combination of a plurality of different codes, and the master station continuously broadcasts the same content a number of times equal to the number of the receiving stations, and the selection is made for each broadcast. The combination order of the plurality of codes constituting the call code is made different from each other, each receiving station selectively receives each selected call code having a different combination order, and each reception station overlaps each other in time. 1. A selective call broadcasting device, characterized in that said broadcasts having the same content are sequentially received and amplified so as to prevent broadcasts from occurring.