JPH0149061B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a selective call communication system with display.

In the early conventional selective call communication system with display, the transmission speed of selective call number information and display information was the same. This is due to the advantage that the base station equipment is simplified, but on the other hand, there are disadvantages as described below. That is, in order to prevent the subscriber capacity from decreasing as much as possible even with display, a method of increasing the transmission speed is generally adopted. Therefore, as the transmission speed increases, the sensitivity naturally decreases. This reduction in reception sensitivity directly leads to a reduction in the service area, which is a major drawback. Therefore, in order to improve this problem, a system has been put into practical use in which the selective calling number information is sent at a low speed as before, and the display information is sent at a high speed. In this system, the selective calling number is transmitted at a low speed as before, so there is an advantage that a service area close to the conventional one can be secured for calls. However, even in this case, the radio system parameters (frequency deviation amount, offset frequency amount) must be adjusted to high-speed data, and in the case of the same channel separation as before, it is necessary to lower the frequency deviation amount than before. Therefore, this method also suffers from a slight decrease in sensitivity, which also has the disadvantage of reducing the service area. Although the subject of the present invention is a selective call communication system with a display, it is important that the present invention can also be used in systems without a display.

Therefore, an object of the present invention is to provide a selective calling system in which the transmission speed of the selective calling number and its display information are different.
The objective is to obtain a system with a display that minimizes the decrease in reception sensitivity, that is, a system that minimizes the reduction in service area.

Another object of the invention is, in addition to the above, to provide a system with a display that is compatible with a system without a display.

According to the present invention, the present invention includes a telephone station, a calling device, a wireless base station having a modem, a FSK modulator, and a transmitter section, and a plurality of receivers with displays that can be selectively called. In a system where the transmission speed of selective calling number information and the transmission speed of display information are different from each other, in order for the calling device to switchably select one of the two transmission speeds, switching information is converted into a code of the selective calling number information. It is a calling device that has the function of inserting into the bit synchronization signal part of the column, and the above-mentioned
Variable FSK, wherein the FSK modulator has means for switching at least one of a frequency shift amount and an offset frequency of the transmitter section according to the switching information.
A selective call communication system is obtained which is characterized by a modulator.

A detailed description will be given below with reference to the drawings.

FIG. 1 is a system configuration diagram showing an example of a conventional selective call communication system. In FIG. 1, 1 is a telephone set used for making calls; 2
is a telephone office on the general switched network. 3 is a calling device which generates a selective calling signal and is the central part of the system. 4, 4' and 4'' are all wireless base stations, which include a modulator/demodulator 5, a frequency shift modulator (FSK modulator) 7 including a frequency divider 6, a frequency converter 8,
It consists of a transmitter section 11 consisting of an exciter 9 and a power amplifier 10, and an array antenna 12. Note 1
3 shows one of the many display-equipped selection receivers as an example.

FIG. 2 is a diagram showing an example of the configuration of the conventionally used FSK modulator 7 mentioned above, where 6 is the frequency divider itself shown in FIG. 1, 21 is a voltage controlled oscillator, and 22
is a reference signal oscillator, 23 and 24 are mixers, 25 is a phase comparator, 26 is a low frequency wave generator, 27 to 29 are band wave generators, 30 is a power amplifier, 31 to 33 are frequency dividers, 34 is a data input, 35 respectively indicate modulator outputs. Next, the operation of the above method will be explained.

The selective calling number and display number inputted from the telephone set 1 arrive at the calling device 3 via the telephone office 2. First, the selective calling number is verified. If the received signal is a registered selective calling number, the display number is also subsequently received. When all display numbers have been received, the selective call number and display number are converted into a selective call signal sequence by the modulator/demodulator 5 of the radio base station 4 and sent to the FSK modulator 7 (frequency divider 6), which outputs the modulated signal. becomes output power from the transmitter section 11, is radiated from the antenna 12, and is sent to the selection receiver 13 with display. Furthermore, since the FSK modulator 7 whose circuit configuration is shown in Fig. 2 is well-known,
In operation, data from the modulator/demodulator 5 is input to the frequency divider 6 via the input terminal 34, and the frequency divider 6 divides the frequency according to the transmission speed of the device, and the modulated output is output from the output terminal 35. It will only be explained that it is sent to the frequency converter 8.

FIG. 3 is a diagram showing the configuration of an embodiment of the present invention. In FIG. 3, components with the same reference numerals as in FIG. 1 represent the same components as in FIG. The calling device 42, which has a function of inserting switching control information (transmission speed information), normally sends data b of the signal a from the calling device to the next stage as is, but while receiving the bit synchronization signal part (however, (no bit synchronization code is included) stops the above-mentioned data transmission and instead transmits a synchronization bit (this will also be included in b), and detects the speed information separately inserted by the calling device 41. 43 is a switching circuit which receives transmission data b and frequency deviation data c and outputs transmission data and frequency division ratio control data as signal d; A mixer (first
45 is a variable FSK modulator, and 46 to 46'' are wireless base stations. Note that e is the offset given to each transmitter. It represents data.

FIG. 4 is a diagram showing details of the configuration of the above-mentioned transmission speed detector 42, in which 51 is a synchronization detection circuit;
2 is a speed information detection circuit, 53 is a control circuit, 54 is a bit synchronization section sending circuit, and 55 is a changeover switch.

FIG. 5 is a diagram for explaining the configuration and operation of the adjustable frequency divider 44 and the switching circuit 43 of a transmitter specified with an offset of 0, and the deviation data c is High.
(Call information code 200bit/s) Variable frequency divider 4
4 is mark data 1/M ^LO , space data 1/
Operates at S ^LO , and when low (display information code 400 bit/s), mark data 1/M ^HO , space data 1/
Operate S ^LO .

FIG. 6 is a diagram showing combinations of frequency division numbers of the variable frequency divider 44 when the offset is + and -. In this figure, High is the high speed of the display information code (in this case
400 bit/s), and Low represents the low speed (200 bit/s) of the call information code.

Here, the calling device 4 mentioned in the explanation of FIG.
The switching control information insertion function for wireless parameter switching in No. 1 will be described in detail.

FIG. 7 is a diagram showing an example of a paging signal sequence for explaining an overview of wireless parameter switching timing. In this case, one frame () of the calling signal string is divided into 15 groups (Group1 to Group15), and one group () is represented by the synchronization signal part SYN of the first word and the receiver 13 (Fig. 1). For example, five selective calling codes #1 to #5 for selectively calling five receivers, and a display code M21 for displaying on three receivers to be selectively called with codes #2, #4, and #5. , M41 and M51. The synchronization signal section ( ) represented by SYN is divided into a bit synchronization signal section and a frame synchronization signal section as shown in the figure. As will be explained later, switching control information is sent from the calling device 3 to the transmission rate detector 42 using this bit synchronization signal section, and a synchronization bit is only inserted here.

As explained above, the transmission speed is assumed to be 200 bits/second for the selective call code and 400 bits/second for the display information code. In order to make the selective call sensitivity the same as before, the synchronization signal SYN and selective call codes #1 to #5 are output at 200 bits/second as before, and the display information codes M#21, M#41, M#51
is transmitted at 400 bits/second and is output from the transmitter with the optimum radio parameters for each transmission rate. The optimal wireless parameters here are determined by taking into consideration the reception band of the receiver and the frequency stability of the transmitter and receiver.

FIG. 7 is a diagram showing an example of the above-mentioned optimal wireless parameters. Note that although both the frequency shift and frequency offset are changed in this figure, there are cases where only one of them is changed.

Next, a control signal for switching transmitter parameters will be specifically explained.

FIG. 8 is a diagram showing the configuration of a bit synchronization signal section () into which control information is inserted in accordance with the signal configuration of FIG. 7 and an original synchronization signal section (). Referring to (), the calling device 3 uses the 7 bits of the bit synchronization section to insert the radio parameter information from the third to eighth word positions (() in FIG. 6). Note that words 1 and 2 are always 200 bits/second, so that information is not necessary. In this figure, "0" represents 200 bits/second, and "1" represents 400 bits/second. As mentioned above, the signal into which the radio parameter information has been inserted is sent to the transmission rate detector 42 via the modulator/demodulator 5, where it is sent to the transmission rate detector 42, which is a general bit synchronization signal, as shown in parentheses in the figure. It is replaced with a 0 dot pattern and sent as part of data signal b.

The reason why the bit synchronization section is used as the switching information in the above is that even if the variable FSK modulator 45 becomes impaired and replacement with the 1/0 pattern described earlier becomes impossible and the data from the calling device 3 is sent out as is. ,
This is because it was designed to be able to be received by a receiver.
In other words, the receiver always maintains bit synchronization, and since the receiver performs bit synchronization based on the change point of the bit synchronization signal, no matter what waveform the data a from the calling device 3 has (change (There is always a point) This is because the receiver will not be unable to receive data.

The variable FSK modulator (45 in Figure 3) plays an extremely important role in the present invention in that it controls the transmitting side and changes the transmission speed, but from a configuration standpoint, it is shown in Figure 2. traditional
FSK modulator 6 and variable FSK modulator 44 (Figure 3)
It was changed to . Therefore, its operation can be easily understood in combination with FIG.

As described above, according to the present invention, even in selective calling communication systems in which the transmission speeds of selective calling numbers and their display information are different, the output of the transmitter is switched to the optimal wireless parameters for each transmission speed. , it is possible to realize a selective calling communication system that minimizes the reduction in reception sensitivity and the reduction in service area. In addition, since the radio parameter information is inserted into the bit synchronization signal, even if the variable FSK modulator 42 that controls the transmitter were to fail and the radio parameter information was output as is from the transmitter, it would be fatal to the receiver. It has no negative impact. Moreover, this method is also compatible with conventional selective call only and no display systems.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram showing an example of a conventional selective call communication system, and FIG. 2 is a diagram showing an example of the configuration of an FSK modulator used in the device shown in FIG.
FIG. 3 is a diagram showing the configuration of one embodiment of the present invention, and FIG. 4 is a diagram showing the transmission speed 4 used in the system of FIG.
2, FIG. 5 is a diagram showing the configuration and operation of the variable frequency divider and switching circuit, and FIG. 6 is a diagram showing the combination of frequency division numbers of the variable frequency divider with respect to offset.
FIG. 7 is a diagram showing an example of a paging signal sequence for explaining the wireless parameter switching timing of the present invention, FIG. 8 is a diagram showing an example of optimal wireless parameters, and FIG. 9 is a diagram showing wireless parameter switching information. This is a diagram illustrating an example, in which () shows the configuration of a bit synchronization signal section sent from the calling device 4 to the transmission rate detector 42, and () shows the configuration of the bit synchronization signal section sent from the transmission rate detector 42 to the transmitter section 11. This figure shows an example of the signal configuration of the bit synchronization signal section. Explanation of symbols: 1 is a telephone, 2 is a general switched network telephone, 3 is a calling device, 4 is a wireless base station, 5 is a modem, 11 is a transmitter section, 13 is a receiver, 41 is a bit synchronization signal section 42 is a transmission speed detector, 43 is a switching circuit, 44 is a variable frequency divider, and 45 is a variable FSK modulator.

Claims (1)

[Claims] 1. Comprising a telephone station, a calling device, a radio base station having a modem, a FSK modulator, and a transmitter section, and a plurality of receivers with displays that can be selectively called,
In a system where the transmission speed of selective calling number information and the transmission speed of display information are different from each other, the switching information for the calling device to selectively select one of the two transmission speeds is used as the selective calling number. A calling device having a function of inserting into a bit synchronization signal part of a code string of information, and means for the FSK modulator to switch at least one of a frequency shift amount and an offset frequency of the transmitter section according to the switching information. A selective call communication system characterized by a variable FSK modulator having a variable FSK modulator.