JPS63232633A - Transmission signal phase synchronizing and controlling system - Google Patents

Abstract

PURPOSE:To synchronize the phase of transmission signal of each transmission station economically by providing a phase difference detection control section to a central station, returning data sent from the central station via a wired line by a returning circuit provided to each transmission station, detecting the phase difference and controlling the phase of transmission of the data. CONSTITUTION:The returned data 30 from a transmission station is demodulated by a demodulator 17 and fed to a phase shifter 14. A bit timing signal recovered by a bit timing recovery circuit 18 is subjected to phase comparison with a clock signal 23 by a phase comparator 15 and a phase difference signal 28 is fed as a control signal of phase shifters 13, 14. The phase difference between sent data 29 and the returned data 30 is detected by the phase comparator 15 to control the phase of the sent data 29 by the phase shifter 13 corresponding to a phase difference signal 28 thereby compensating the change in the transmission delay quantity of a wired line, then the synchronizing state of the phase of the transmission signal of a transmission station with the phase of the transmission signal of other transmission station is kept.

Description

[Detailed Description of the Invention] [Summary] A paging system that performs paging communication for a pager receiver by transmitting modulated waves of the same frequency from a plurality of distributed transmitting stations.
In the system, by looping back the data sent from the central station at the transmitting station, the central station can identify whether or not the transmitted signal phase has shifted, and if the transmitted signal phase has shifted, it can correct the phase shift. This control is performed so that the transmission signal phases of each transmitting station are the same.

[Industrial application field]

The present invention transmits data sent from a central station as a modulated wave of the same frequency from each transmitting station, performs paging communication for a pager receiver, and transmits signal phase synchronization that synchronizes the transmitting signal phase of each transmitting station. This is related to the control method.

In a paging system, a plurality of transmitting stations each connected to a central station via wired lines transmit modulated waves of the same frequency to perform paging communication for a pager receiver.
Since modulated wave signals from adjacent transmitting stations can be received at the same level within the equal electric field region of those transmitting stations, if the received signals are out of phase, they interfere with each other and reception identification becomes impossible. Therefore, it is necessary to adjust the phase of the transmitted signal from the transmitting station to enable reception identification even within a constant electric field region. There is a need for a means for easily synchronizing the phases of transmission signals of each transmitting station. Note that the transmission signal phase is
It indicates the bit phase of the transmitted data, not the transmitted carrier wave phase.

[Conventional technology]

A paging system that performs paging communication for a pager receiver (pager), for example, as shown in FIG. Stations 62-1 to 62-n are connected to perform paging communication to pager receivers 65-1 to 65- within the respective service areas 64 of these transmitting stations 62-1 to 62-n.

For example, when a subscriber 67 accommodated in the exchange 66 calls the pager receiver 65-1, the call data is transferred from the exchange 66 to the central office 61 in accordance with the dial information of the subscriber 67. to each transmitting station 62-1 to 62'
-n via wired lines 63-1 to 63-n, and from each transmitting station 62-1 to 62-n, for example, the calling data is FSX-modulated and transmitted at the same frequency of 280 MHz. .

FIG. 8 is an explanatory diagram of the signal formant, and shows data DIl to D18, . . . , I) for eight pager receivers.
1 batch B1 with nl to Dn8 as 1 batch each
Alternatively, a preamble word PW including a synchronization signal is added to the beginning of a plurality of batches Bl-Bn. Furthermore, if the total number of data is not 8, dummy data is added to make the batch equivalent to 8 data to form a batch.

It is also possible to transmit data using a normal fixed length frame structure.

The pager receivers 65-1 to 65- have data Dll to
It receives and identifies the identification code included in Dn8, and when it receives and identifies the data for its own pager receiver, it rings a bell. In addition to this calling method, there is also known a method in which simple character information is also transmitted as data and the characters are displayed on a display section provided in a pager receiver to transmit the simple information.

Further, the wired lines 63-1 to 63-n connecting the central station 61 and each of the transmitting stations 62-1 to 62-n are generally public lines. Therefore, a detour connection may be made due to a failure in a switching center, relay line, or the like. For example, the wired line 6 between the central station 61 and the transmitting station 62-1
3-1 may be switched and connected to the line 63'' shown by the dotted line due to the occurrence of a failure.

Furthermore, since the pager receiver 65-2 is located at a position where it can receive only the modulated wave signal from the transmitting station 62-1, the pager receiver 65-2
Even if the transmission signal phase of -1 changes, there is almost no effect and reception identification becomes possible. If this happens, the modulated wave signals from both transmitting stations 62-1 and 62-2 will be received at the same time at the same level, and if the received signals are out of phase, they will interfere with each other and make reception identification impossible. Become.

FIG. 9 is an explanatory diagram of the received signal phase. When the received signal phase of the modulated wave signal from the transmitting station shown in ta) is taken as a reference, the received signal phase of the modulated wave signal from another transmitting station is ( b
), if the phases are the same, reception identification is possible without any problem even in the uniform electric field region. However, as shown in [C], when the phase is shifted by 180 degrees with respect to the reference received signal phase, reception identification becomes completely impossible. Also Td
), if there is a phase shift of 90 degrees with respect to the reference received signal phase, there will be many errors in reception identification, so normally each transmitting station 62-
It is necessary to adjust the transmission signal phase in 1 to 62-n.

Therefore, the transmission delay time due to the wired lines 63-1 to 63-n between the central station 61 and the transmitting stations 62-1 to 62-n is compensated at the central station 61, and each transmitting station 62-n is 1-62
-n transmission signal phases are adjusted so that they are the same, -. However, even if such adjustments are made at the time of system startup, as mentioned above, the wired lines 63-1 to 63
-n switching connections may be performed, and in that case, the transmission delay time may change significantly. Thereby,
The received signal phase within the constant electric field region shifts, making reception identification impossible.

In order to solve such problems, each transmitting station 62-1 to 62-6
When installing a receiver at each station 2-n and adjusting the transmission signal phase shift, temporarily stop the transmission of all transmitting stations 62-1 to 62-n, and then have each station transmit to one station in turn. This is received by a receiver installed at a transmitting station that is not in the center, the receiver or the central station 61 identifies the transmitted signal phase difference of each transmitting station, and the central station 61 transmits the signal so that the transmitted signal phase difference is corrected. The timing of transferring the call information to the stations 62-1 to 62-n was adjusted.

[Problem that the invention seeks to solve]

As mentioned above, in the conventional paging system, each of the transmitting stations 62-1 to 62-n is provided with a receiver, which has the drawback of increasing costs.

Furthermore, each receiver is used only when adjusting the transmission signal phase and cannot receive transmissions from its own station, so its usage efficiency is low, and the transmitting stations 62-1 to 62-n are unmanned. Therefore, providing a receiver as extra equipment other than the transmitter for calling communication has the drawback of causing maintenance problems.

An object of the present invention is to economically synchronize the transmission signal phases of each transmitting station.

[Means for solving problems]

The transmission signal phase synchronization control method of the present invention monitors the transmission signal phase at the central station using return data from each transmission station and controls the transmission signal phase, as shown in FIG. I will explain.

A central station 1 and a plurality of distributed transmitting stations 2-1 to 2-
n are respectively connected via wired lines 3-1 to 3-n such as public lines, and data from the central station 1 is transmitted to each transmitting station 2-n.
1 to 2-n as modulated waves of the same frequency to perform paging communication for the pager receiver, a phase difference detection control unit 4 is provided in the central station 1, and data is transmitted to each transmitting station 2-1 to 2-n. A folding circuit 5 is provided.

Data from the data sending unit 7 of the central station 1 is sent to each transmitting station 2-1 to 2-n via the phase difference detection control unit 4.
In each of the transmitting stations 2-1 to 2-n, the transferred data is added to the transmitter 6 via the folding circuit 5, subjected to modulation, frequency conversion, amplification, etc., and transmitted from the antenna. 5
A part or all of the data is looped back and transferred to the central station 1, and this looped data is compared with the transmitted data by the phase difference detection control section 4 to detect a phase difference. It controls the sending phase of sending data to the stations 2-1 to 2-n.

[Effect]

The return circuits 5 of each of the transmitting stations 2-1 to 2-n are controlled to copy the transferred data and return it at all times or at predetermined intervals, or to return the transferred data during maintenance. Further, the phase difference detection control section 4 of the central station 1 compares the transmitted data and the returned data to detect a phase difference. This phase difference corresponds to the distance between the wired lines 3-1 to 3-n, and when the phase difference becomes large, the wired lines 3-1 to 3-n are switched and connected to a long-distance detour line. In this case, the phase of the transmitted data is advanced to compensate for the transmission delay due to the extended wired line, and thereby the transmitting stations 2-1 to 2-
This is to maintain the phase synchronization of the transmission signal from n.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of a main part of an embodiment of the present invention, showing a portion of the phase difference detection control section 4 (see FIG. 1) of the central station I corresponding to one transmitting station. In the figure, 11 is an encoder, 12 is a shift register, 13.14 is a phase shifter, and 15 is a shift register.
is a phase comparator, 16 is a modulator, 17 is a demodulator, 18 is a bit timing recovery circuit, 19 is a frame synchronization circuit, 2
0 is a counter, and 21 is a 1/2 circuit. Further, 22 is call information transferred from the exchange, 23 is a clock signal, and 24
is a frame synchronization signal, 25 is a frame synchronization signal from the frame synchronization circuit 19, 26 is a bit difference signal from the counter 20, 27 is a control signal for the shift register 12, 28
is a phase difference signal from the phase comparator 15, 29 is sending data, and 30 is return data.

The paging information 22 is converted by the encoder 11 into data for paging communication of the pager receiver, and is added to the shift register 12. The output data of this shift register 12 is applied to a modulator 16 via a phase shifter 13. The modulator 16 and the demodulator 17 correspond to a modem for transmitting and receiving data via a wired line, and the transmission data 29 is sent to the transmitting station via the wired line.

Also, the return data 30 from the transmitting station is demodulated by the demodulator 17 and applied to the phase shifter 14. The output signal of this phase shifter 14 is applied to a bit timing recovery circuit 18 and a frame synchronization circuit 19.

The bit timing recovered by the bit timing recovery circuit 18
The timing signal is a clock signal 23 and a phase comparator 15.
The phases are compared in the phase shifter 13. and the phase difference signal 28 is sent to the phase shifter 13.
14 control signals.

The central station and the transmitting station are connected by a 4-wire wired line,
Even in the case of switching connection to the detour line, the switching connection is made when there are four lines, and the phase difference between the sent data and the return data is doubled because the data travels back and forth on the wired line. The phase difference between such sent data 29 and return data 30 is detected by the phase comparator 15, and the phase of the sent data 29 is controlled by the phase shifter 13 in accordance with the phase difference signal 28, and the phase of the sent data 29 is controlled by the phase difference signal 28. Since changes in the amount of transmission delay are compensated for, the phase of the transmitting signal of the transmitting station can be maintained in synchronization with the phase of the transmitting signals of other transmitting stations.

Further, the frame synchronization signal from the frame synchronization circuit 19 and the reference frame synchronization signal 24 are added to the counter 20, and the difference between them becomes the bit difference signal 26. for example,
The bit difference signal 26 can be obtained by clearing the counter 20 by the frame synchronization signal 24 to start counting by the clock signal 23, and by stopping the counting by the frame synchronization signal from the frame synchronization circuit 19.

Therefore, the shift register 12 is controlled in accordance with the phase difference between the frame synchronization signals between the sending data 29 and the return data 30, and the amount of transmission delay on the wired line changes significantly, causing a shift in the transmission signal phase over multiple bits. Even in such a case, by controlling the advance or delay of the output bits of the shift register 12, it is possible to prevent bits from being dropped or duplicated.

FIG. 3 is a block diagram of a transmitting station according to an embodiment of the present invention,
3I is a demodulator, 32 is an amplifier, 33 is a modulator, 34 is a frequency converter, 35 is a local oscillator, 36 is a bandpass filter,
37 is a power amplifier, 38 is an antenna, 39 is a folding circuit,
Reference numeral 40 denotes a modulator, and the modulator 40 and demodulator 31 constitute a modem for a wired line. Data 41 received via the wired line is demodulated by the demodulator 31, and the data 42 modulated by the modulator 40 is demodulated by the demodulator 31. is sent to the central office via a wired line.

The data 41 transferred from the central station via the wired line is
It is demodulated by a demodulator 31, amplified by an amplifier 32, and applied to a modulator 33. This modulator 33 has jSK
The modulated output signal is applied to the frequency converter 34, mixed with the local oscillation signal from the local oscillator 35, and converted to a transmission frequency of, for example, 280 MHz, and the transmission frequency is set as the center frequency. The amplified output signal is applied to a power amplifier 37 via a bandpass filter 36 having a pass band of 1000 kHz, and the amplified output signal is transmitted from an antenna 38.

Further, the data demodulated by the demodulator 31 is folded back by the folding circuit 39 and modulated by the modulator 40, and the modulated data 42 is transferred to the central office via a wired line. This loopback circuit 39 can constantly copy and loop back data, or loop back demodulated data manually during maintenance or under control from the central station.

FIG. 4 is an explanatory diagram of the bit difference. When (a) is used as the reference frame synchronization signal 22 (see FIG. 2), the frame synchronization signal 25 from the frame synchronization circuit 19 is as shown in (b). If the timing is the same, the count content of the counter 20 will be zero, and there will be no bit difference. Also (C
), when the frame synchronization signal 25 is delayed by L bits from the reference frame synchronization signal 22, the count content of the counter 20 becomes L, and this becomes the bit difference signal 2.
It becomes 6. This bit difference is caused by the data going back and forth on the wired line, so in order to eliminate the bit difference at the transmitting station, it is necessary to transmit L/2 bits separately. It turns out. For this purpose, the bit difference signal 26 is halved by the 172 circuit 21 and used as the control signal 27 for the shift register 12.

In the above case, the amount of transmission delay increases and the frame signal 25 of return data is delayed by L bits.
If the transmission delay is reduced by switching to a line with a shorter distance, the return data frame signal 25 will lead the reference frame signal 24, and the number of bits will be shifted by half the number of lead bits. It is only necessary to delay the output using the register 12.

FIG. 5 is an explanatory diagram of the phase difference, where (a) is the reference clock signal and (b) is the bit timing signal from the bit timing recovery circuit 18, the phase comparator 15
As a result, a phase difference signal 28 corresponding to the phase difference θ is output. This phase comparator 15 has, for example, a characteristic shown by a curve 50 in FIG. 6, and outputs a voltage proportional to the phase difference, which is used as a phase difference signal 2.
14. In this case, the phase difference θ is caused by the data traveling back and forth on the wired line, but since it is connected to the transmitting and receiving systems respectively by phase shifters 13 and 14, the phase difference θ is θ/2. This is done individually.

At the time of system startup, etc., the central station 1 and each transmitting station 2-1
Wired lines 3-1 to 3 in normal connection state between ~2-n
-n (see Figure 1), the phase difference signal 28 of the phase comparator 15 and the bit difference signal 26 of the counter 20 are set to zero, and the transmission signal phase of each transmitting station is adjusted. By synchronizing the signals and ensuring that there is no reception phase shift even in the equal electric field region, the wired connection can be changed when switching to a long-distance detour line or switching to a short-distance line. A change in the transmission delay amount of the line is detected by the phase comparator 15 and the counter 20, and a phase difference signal 28 is detected.
and the bit difference signal 26, the phase and bit position of the data sent from the central station to the transmitting station can be controlled to compensate for changes in the transmission delay amount of the wired line and maintain the synchronized state of the transmitted signal phase. .

〔Effect of the invention〕

As explained above, the present invention provides the phase difference detection control section 4 in the central station 1, and the folding circuit 5 in each transmitting station 2-1 to 2-n.
The data sent from the central station 1 via the wired lines 3-1 to 3-n is returned by the return circuit 5, and the phase difference detection control section 4 compares the sent data and the returned data to determine the phase difference. is detected, and the sending phase of the sending data to the transmitting station is controlled in accordance with the phase difference.

Therefore, due to a change in the amount of transmission delay due to the switched connection of the wired lines 3-1 to 3-n, the phase of the transmitted signals of the transmitting stations 2-1 to 'l-n changes, and interference occurs in the constant electric field region. If this occurs, the phase difference detection control unit 4 of the central station 1 detects this and controls the phase of data transmission to the transmitting station whose transmission delay amount has changed. condition can be maintained. Since the phase difference is monitored and controlled at the central station 1, maintenance and operation are easy, and each transmitting station 2
Since there is no need to provide a receiver for each of -1 to 2-n, there is an advantage that an economical system can be constructed.

[Brief explanation of the drawing]

Fig. 1 is a diagram explaining the principle of the present invention, Fig. 2 is a block diagram of main parts of an embodiment of the invention, Fig. 3 is a block diagram of a transmitting station in an embodiment of the invention, and Fig. 4 is an explanation of bit differences. Fig. 5 is an explanatory diagram of phase difference, Fig. 6 is an explanatory diagram of phase difference, Fig. 7 is an explanatory diagram of conventional example, Fig. 8 is an explanatory diagram of signal format, and Fig. 9 is an explanatory diagram of reception. It is an explanatory diagram of a signal phase. 1 is a center station, 2-1 to 2-n are transmitting stations, and 3-1 to 3-n
is a wired line, 4 is a phase difference detection control unit, 5 is a return circuit, 6
is a transmitter, and 7 is a data sender.

Claims (1)

[Claims] A central station (1) and a plurality of distributed transmitting stations (2-1
~2-n) are respectively connected via wired lines (3-1~3-n), and data from the central station (1) is transmitted from the plurality of transmitting stations (2-1~2-n). In a wireless communication system in which a modulated wave of the same frequency is transmitted to perform paging communication for a pager receiver, the central station (1) is provided with a phase difference detection control section (4), and each of the transmitting stations (2- 1 to 2-n) is provided with a data return circuit (5), and the data sent from the central station (1) is transmitted to the return circuit (5).
5), the phase difference detection control unit (4) compares the sent data and the returned data to detect a phase difference;
A transmission signal phase synchronization control system characterized in that the transmission phase of transmission data is controlled based on the phase difference so that the transmission signal phases of the respective transmission stations (2-1 to 2-n) are the same.