JPS60182231A - Selective call communication system - Google Patents

Abstract

PURPOSE:To attain sure synchronism even if the signal speed of a call and a synchronism word is different by inserting a preamble signal from which (n+1)- time or over polarity change is obtained including a bit synchronizing signal of the synchronism word when the call word just before the synchronism word is an idle word. CONSTITUTION:The call word placed just before the synchronizing word is formed forcibly into an idle word at each several minutes among words transmitted repetitively from the transmission side, the preamble signal is inserted to the idle word and the result is transmitted. The preamble signal consists of a repetitive signal of ''00110011...'' having a bit period of 2.5msec. Thus, the preamble signal is formed apparently into the same constitution as that of the bit synchronism signal having a period of 5msec. On the other hand, a receiver supervises the leading of the reception code at the same time when power is applied, and if the timing of leading satisfies the condition of 5msecXK+ or - 0.625msec to the preceding lead timing, the synchronism is discriminated instantly to synchronize in case the signal speed of the call word and the synchronism word is different.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a method for transmitting a selective calling signal in which a message code is added to an individual number code by inserting it into a calling word. This invention relates to improvements in selective calling communication systems with different signal speeds.

[Technical background of the invention]

As one of the selective calling methods, an individual number code and a message code are inserted into the information pit of a selective call signal and transmitted.The receiving side compares the individual number code with its own number, and when the two match, a sound is generated. There is a device that displays a call using a message code, and at the same time decodes the message code and visually displays it. Recently, such a so-called selective call signal with display and a selective call signal for ringing in which only an individual number code is inserted are assigned to different groups in one frame and operated in one system. A method has been proposed. FIG. 1 FL shows an example of the allocation of each of the selective call signals mentioned above, in which 1 to 10 of the 15 groups constituting one frame are used as selective call signals for ringing, and 11 to 15 are assigned to display. Each is assigned to a selective call signal. Note that FIG. 1 GP shows the signal configuration of each group 15, which consists of a synchronization word and eight call words.

By the way, the above-mentioned selective call signal for ringing is generally as shown in Fig. 2 (
, ) shows the so-called 31°1 eB (16 bits of information bits plus 14 check bits).
On the other hand, the selective call signal with display consists of 44 bits, 18 bits, 18 bits,
Che, you're fired.

It consists of 6 2 , 448CH codes with additional bits added. Therefore, in the method in which both selective calling signals are assigned in the same system, the signal speed of the selective calling signal with display is set to be twice the speed of the selective calling signal for sound (bit period is 1/2). It is set to . The signal speed of each calling word except for the sync word and the sync word is set to twice the signal speed of the sync word.

[Problems with background technology]

However, the conventional method described above has the following problems. In other words, by making the signal speed of the selective call signal with display twice the speed of the synchronization word, for example, when power is turned on during any one of the call words, the signal phase of the call word will be different from that of the synchronization word. The signal phase may deviate by 180° from C8 in FIG. 4, for example, as shown in FIG. 4 HS'. Note that H8 in FIG. 4 shows a case where the phases match.

In this way, if the phase of the received signal is shifted by 180°,
The receiver once adjusts the phase of the regenerated clock to this phase,
Thereafter, the phase correction operation is performed by receiving the bit period signal (the first 9 bits shown in FIG. 3) of the synchronization word.

Here, this phase correction operation is performed, for example, as follows. That is, when a reception signal (NRZ code) is first received, the rising edge of each bit is detected, and the timing of these rising edges is 5 m5 ec x ±0.625 m5 ec (K is any integer) with respect to the previous rising timing. The instantaneous S/N is determined to be good when the following conditions are met. Then, when this good judgment is made seven times in a row, the phase is corrected.

However, since the bit synchronization signal does not have 9 pins as shown in Fig. 3, it is not possible to perform instantaneous SA determination seven times in a row within this pit synchronization signal period, and the fourth and subsequent determinations cannot be made. This will be done in the frame synchronization signal.

Therefore, at the time when the phase is corrected, the frame synchronization signal period has already entered, and the frame synchronization signal cannot be detected. If this frame synchronization signal cannot be detected, the receiver directly shifts to battery saving after the period of its own group has elapsed. Then, when one frame period has passed, the power is turned on again, but even in this case, there is a possibility that the phase of the calling word signal is 180 degrees out of phase with the phase of the synchronization word. If a phase shift occurs, as mentioned above, the frame synchronization signal cannot be detected again.

As described above, in the conventional method, it is difficult to reliably detect a frame synchronization signal in a short period of time, and in the worst case, there is a risk that detection will not be possible semi-permanently, which is extremely undesirable.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a selective paging communication system that can reliably maintain a bit period even when the signal speeds of a paging word and a synchronization word are different.

[Summary of the invention]

In order to achieve the above object, the present invention provides a total of N+1 or more polarity change points including the bit periodic signal of the synchronization word when the word F is an empty word. A preamble signal is inserted so as to prevent the bit synchronization monitoring period from interfering with the frame synchronization signal of the synchronization word.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

The transmitting station to which the selective call communication method of this embodiment is applied is configured to forcibly empty the call word 8, which is placed immediately before the synchronization word, out of the words that are repeatedly transmitted without interruption every few minutes. A preamble signal is inserted into this empty word and transmitted. This preamble signal has a bit period of 2.5 masc as shown in FIG.
0011...'' is made up of repeated signals.

In other words, this preamble signal has an apparent upper period of 5.
It has the same configuration as the bit synchronization signal of +n566.

On the other hand, the receiver starts monitoring the rising edge of the received code as soon as the power is turned on, and each rising timing is S m5ec X K±0.6 with respect to the preceding rising timing.
If the condition of 25 m5ec is satisfied, the instantaneous S/N is determined to be good. Then, when this good judgment is made 7 times in a row, 1
Correct the phase of the regenerated clock. Note that the above values are integers. Further, even after adjusting the phases as described above, the receiver constantly monitors the phase of the incoming received code, and when a phase deviation is detected, the receiver performs the above-described phase correction operation again from that point.

Further, in parallel with the bit synchronization monitoring operation described above, the receiver performs various operations such as monitoring frame synchronization and collating individual number codes in accordance with the reproduced clock.

Therefore, when the power is turned on, the phase of the selection call signal with display inserted into the call word is 18% relative to the synchronization word signal.
If there is a 0° shift, the receiver adjusts the phase of its own regenerated clock to this shifted phase. However, when the call word 8 arrives, since a preamble signal is inserted into the call word 8, the receiver detects that the first rising edge of the preamble signal is detected and the receiver is out of synchronization. The phase correction operation is started based on this assumption. Then, when the seventh rising edge of the preamble signal is detected, and it is determined that the temporary signal s/)J is good, at this point, the regenerated clock is shifted to the phase that matches the phase of the synchronization word signal. Correct the phase of.

Therefore, as mentioned above, even if the phase of the calling word is shifted by 180' and the phase of the reproduced clock is corrected to this phase, the incorrect phase of the reproduced clock is
It falls within the period of call word 8 to ensure that it is corrected to the correct phase. Therefore, at the time when the frame synchronization signal of the synchronization word arrives, the phase of the reproduced clock definitely matches the bit synchronization signal, so that the frame synchronization signal can be reliably detected. In addition, in this embodiment, the preamble signal is inserted every few minutes to perform the above-mentioned phase correction, so there is no need to make the call word 8 an empty word during the several minute period, and as a result, the call word 8 does not need to be empty during the several minute period. word 8
There is an advantage that the above-mentioned phase correction operation can be carried out without imposing any restrictions on the use of.

It should be noted that the present invention is not limited to the above embodiments.
For example, in the embodiment described above, the preamble signal is inserted into the entire area of the calling word 9-8, but it may be inserted only into a part of the latter half of the word. However, in this case, at least 7 + 1 rising edges must be detected before entering the frame synchronization signal period, so a total of 7 + 1 or more times including the pit synchronization signal (9 bits, G) must be performed. It is necessary to determine the wave number of the preamble signal so that the rising point can be obtained.

Further, the same applies even if the signal speed of the calling word is three times or more the signal speed of the synchronization word.

〔Effect of the invention〕

As detailed above, according to the present invention, when this word is an empty word, a total of N+1 or more polarity change points can be obtained in the call word immediately before the synchronization word, including the bit synchronization signal of the synchronization word. By inserting the serial pull signal in this way, even if the phase of the calling word differs from the phase of the synchronization word, the synchronization monitoring period will not enter the frame synchronization signal period of the synchronization word, and at the latest the bit synchronization In a signal period of 10 - the phase correction can be completed.

Therefore, according to the present invention, it is possible to provide a selective paging communication system that can always ensure bit synchronization even when the signal speeds of the paging word and the synchronization word are different.

[Brief explanation of drawings]

Figures 1 to 4 are for explaining the conventional selective call communication system. Figure 1 is a schematic diagram showing the signal structure of frames and groups, and Figures 2 (-) and (b) are respectively A schematic diagram showing the signal configuration of a sound selection call signal and a selection call signal with display. FIG. 3 is a signal waveform diagram showing the signal configuration of the synchronization word. FIG. 4 is a signal waveform diagram showing the phase relationship of the call word to the synchronization word. , FIG. 5 is a signal waveform diagram of a nor-amplified signal used in the selective call communication system in one embodiment of the present invention. FL...Frame, GP...Glue 7', C8...
-Phase of synchronization word signal, H8, H8'...Phase of calling word signal.

Claims (2)

[Claims] (1) A selective calling signal with a different signal speed from the synchronous word signal is inserted into the calling word, and the receiving side receives the synchronous word signal and the selective calling signal and sets the polarity change point of each pit to a predetermined value. In a selective call communication system that performs phase correction when detected N times in a row under the condition, the call word immediately before the synchronization word is N+1 times in total, including the pit synchronization signal of the synchronization word when the call word is empty. A selective call communication system characterized in that a preamble signal is inserted so as to obtain the above polarity change points. (2) The calling word immediately before the synchronization word signal is forced to be an empty word at regular intervals, and a preamble signal is inserted into this empty word. selective call communication method.