JPS63232632A - Transmission signal phase synchronizing and controlling system - Google Patents

Abstract

PURPOSE:To economically synchronize the phase of a transmission signal of each transmission station by providing a phase difference detection control section to each transmission station to detect changes in transmission delay quantity of a wired line thereby controlling the signal phase sent from the transmission section. CONSTITUTION:The relation between the phase of a clock signal from an oscillator 14 and the phase of a signal via a wired line 10 is adjusted in advance and when a phase difference between a demodulation signal and a clock signal from the oscillator 14 is detected by a phase difference control section 12, the phase of the demodulation signal is controlled to correct the phase difference and fed to a bit difference control section 13. The phase of the transmission signal is controlled by the phase difference control section 12 and a bit difference control section 13 and the phase of the transmission signal is controlled to compensate the change in the transmission delay quantity due to switching connection or the like of the wired line 10 to keep the synchronization of the phase of the transmission signal of each transmission station. Thus, even when the transmission delay is change by the switching connection of wired lines 3-1-3-n, the phase of the transmission signal of the stations 2-1-2-n is controlled to be identical. Thus, it is not required to provide any receiver to the transmission stations 2-1-2-n, then the system is constituted economically.

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, the transmission signal phases of each transmitting station are synchronized to prevent interference due to phase shifts between adjacent transmitting stations in a uniform electric field region.

[Industrial application field]

The present invention performs paging communication for a pager receiver by transmitting data from a central station as a modulated wave of the same frequency from each transmitting station, and also performs transmitting signal phase synchronization that synchronizes the transmitting signal phase of each transmitting station. This concerns 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 be able to identify reception even within a constant electric field region by adjusting the phase of the transmitted signal of the transmitting station. 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- in the respective service areas 64 of the 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. From each transmitting station 62-1 to 62-
The call data is transferred to the transmitter station 63-1 to 63-n via wired lines 63-1 to 63-n, and from each transmitting station 62-1 to 62-n, the call data is, for example, FSK-modulated and transmitted at 280 MHz.
Sent in liquid numbers.

FIG. 7 is an explanatory diagram of the signal format, and shows data DIl to D18, ..., Dn for eight pager receivers.
A preamble word PW including a synchronization signal is added to the beginning of one batch B1 or a plurality of batches 81 to Bn, with each of batches 1 to Dn8 being one batch. 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 regular fixed length frame structure.

°The pager receivers 65-1 to 65- have data DLLs.
This is to receive and identify the identification code included in ~Dn8, and to ring a bell when the data for the own pager receiver is received and identified. 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 wire diagram vA between the central station 61 and the transmitting station 62-1
63-1 may be switched and connected to line 63' shown by a 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. 8 is an explanatory diagram of the received signal phase, and when the received signal phase of the modulated wave signal from the transmitting station shown in (a) is taken as a reference, the received signal phase of the modulated wave signal from other transmitting stations 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 (d
As shown in FIG. 1, 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, the wired lines 63-1 to 63-
n switching connections may be performed, and in that case, the transmission delay time may vary greatly. As a result, 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 inside the center, and then sent to the transmitting section of each transmitting station.

From the central station 61 to the transmitting station 62-1, the receiver or the central station 61 identifies the phase difference and corrects the transmitted signal phase difference.
This was to adjust the timing of transferring the call information to 62-n.

[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 phase of a transmitted signal and cannot receive transmissions from its own station, resulting in low usage efficiency.

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 system of the present invention detects a change in the amount of transmission delay at each transmitting station and synchronizes the transmission signal phase, and will be explained with reference to FIG.

A central station 1 and a plurality of distributed transmitting stations 2-1 to 2-
The transmitting stations 2-1 to 2.n are connected to each other via wired lines 3-1 to 3-n, such as public lines, respectively. -n transmits a modulated wave of the same frequency to perform paging communication for the pager receiver, and each transmitting station 2-1 to 2-n is provided with a phase difference detection control section 4, and the wired line 3-1 to 3-n is Each transmitting station 2 detects a change in the amount of transmission delay due to the switching connection of
-1 to 2-n transmission signal phases are synchronized.

[Effect]

The phase difference of the call information transferred from the central station 1 via the wired lines 3-1 to 3-n with respect to the reference phase is detected by the phase difference detection control unit 4 of the transmitting stations 2-1 to 2-n. Ru. As this reference phase, it is possible to use the output signal of a high-precision oscillator or the output of an oscillator (such as t') that is phase-synchronized with the reception phase of the signal from the central station 1 as a reference.

For example, when any of the wired lines 3-1 to 3-n is switched to a line that takes a large detour, or conversely, when the line that used to take a large detour is switched to a short-distance line, the communication between the central station 1 and The amount of transmission delay between the station and the station will change,
As a result, the phase of the transmission signal from the transmitter 5 changes.

When the reception phase of the signal from the central station 1 changes in this way, the phase difference detection control section 4 detects the phase difference,
When the amount of transmission delay increases, the phase of the signal applied to the transmitter 5 is advanced, and when the amount of transmission delay decreases, the phase of the signal applied to the transmitter 5 is delayed, so that the transmission can be adjusted according to the change in the amount of transmission delay. This is intended to suppress changes in signal phase and synchronize transmission signal phases. Note that synchronization is not required for the transmission carrier phase.

〔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 transmitting station according to an embodiment of the present invention,
10 is a wired line, 11 is a demodulator, 12 is a phase difference control unit,
13 is a bit difference control unit, 14 is an oscillator, 15 is a modulator,
16 is a frequency converter, 17 is a local oscillator, 18 is a bandpass filter, 19 is a power amplifier, and phase difference control cloth 12. The phase difference detection control unit 4 is controlled by the bit control unit 13, oscillator 14, etc.
are configured, including a modulator 159 and a frequency converter 16. Local oscillator 17. A transmitting section 5 includes a bandpass filter 1B, a power amplifier 19, and the like.

The call data transferred from the central station to each transmitting station is modulated by a modem or the like and sent to the wired line 10.
At the transmitting station, the signal is demodulated by a demodulator 11. Further, the relationship between the clock and signal phase from the oscillator 14 and the signal phase via the wired line 10 is adjusted in advance, and the phase difference between the demodulated signal and the clock signal from the oscillator 14 is detected by the phase difference controller 12. bit difference control unit 13 , the phase of the demodulated signal is controlled to correct the phase difference.
added to.

The bit difference control unit 13 detects a bit jump that occurs when the wired line 10 is switched and connected, and performs control so that bit dropout, bit duplication, etc. do not occur.

The signal whose phase difference and bit difference have been controlled is applied to a modulator 15, for example, FSX modulated, and then sent to a frequency converter 16.
added to. In this frequency converter 16, the local oscillation signal is mixed with the local oscillation signal from the local oscillator 17.
The signal is converted to a transmission frequency of 0 MHz, is applied to a power amplifier 19 via a bandpass filter 18 having a passband centered around this transmission frequency, and the amplified output signal is transmitted from an antenna.

This transmission signal phase is controlled by the phase difference control section 12 and the bit difference control section 13, and
The transmission signal phase is controlled so as to compensate for the change in the amount of transmission delay due to the switching connection of O, etc., and the synchronization of the transmission signal phase of each transmitting station is maintained.

FIG. 3 is a block diagram of a phase difference detection control section according to an embodiment of the present invention, in which 20 is a wired line, 21 is a demodulator, 22 is a frame synchronization circuit, 23 is a bit timing recovery circuit, 2
4 is a phase shifter, 25 is a shift register, 26 is a phase comparator, 27 is a counter, 28 is a switch circuit, 29 is an oscillator, and 30 is a frame synchronization circuit.

The signal transferred from the central station via the wired line 20 is demodulated by the demodulator 21 and sent to the phase shifter 24 and shift register 2.
5 to the modulator (see FIG. 2). Further, the bit timing signal is reproduced by the bit timing reproducing circuit 23, and frame synchronization is performed by the frame synchronizing circuit 22. Then, the phase comparator 26 reproduces the signal using the clock signal from the oscillator 29 as a reference.
A phase difference between the throat timing signals is detected, and the phase shifter 24 is controlled in accordance with the phase difference.

For example, if the phase of the bit timing signal lags behind the clock signal, this is because the transmission delay amount increases due to switching to a long-distance wired line, so the phase shifter 24 advances the phase of the demodulated signal. . If the phase of the bit timing signal is ahead of the clock signal, this means that the transmission delay amount is reduced by switching to a short-distance wired line, so the phase shifter 24 delays the phase of the demodulated signal. Through such control, the transmitted signal phase is controlled and synchronized with the transmitted signal phase of other transmitting stations, so that a phase shift that makes reception identification impossible even in the equal electric field N range does not occur. can do.

Further, the frame synchronization signal from the frame synchronization circuit 22 and the frame synchronization signal from the frame synchronization circuit 30 are added to the counter 27 to detect the amount of bit delay. The shift register 25 is controlled in accordance with this bit difference to prevent data bits from being dropped or duplicated.

The oscillator 29 uses a high-precision oscillator, and its oscillation phase is set corresponding to the distance from the central station at the time of system start-up, etc., and thereafter, the clock signal from this oscillator 29 is used as a reference. However, since a high-precision oscillator is expensive, for example, as shown in FIG. /D converter (A/D) 33. Memory (MEM)34. A configuration may be used in which the signal is held in a holding circuit 31 including a D/A converter (D/A) 35 and a signal with a set phase is output from the voltage controlled oscillator 32.

This holding circuit 31 applies a control signal to the switch circuit 28, turns the switch circuit 28 on, and uses a frame synchronization signal or the like as a reset signal, for example, every few hours or at night when the frequency of use is extremely small. memory 3
In addition to 4, after clearing the stored control voltage, the phase difference voltage from the phase comparator 26 at that time can be stored as a new control voltage.

FIG. 3 shows a case where the switch circuit 28 is turned on by a control signal during maintenance, etc., and the frame synchronization signal from the frame synchronization circuit 22 is used as a reset signal, and the control voltage to be held in the holding circuit 31 is shown. can use the phase difference signal from the phase comparator 26 at that time.

FIG. 5 is an explanatory diagram of bit difference detection, in which (a) is a reference frame synchronization signal from the frame synchronization circuit 30, (bl,
(C) shows a frame synchronization signal from the frame synchronization circuit 22. In the state of (b), there is no deviation of 1 bit or more, so the content of the counter 27 is O. In this case, for example, by clearing the counter 27 by the reference frame synchronization signal, counting the clock signal from the oscillator 29, and stopping the count by the frame synchronization signal from the frame synchronization circuit 22, (b
) In the case of the state, it is the count content of O, and in the case of the state (C1), it is the count content of the L bit.

When the wired line 20 is switched and connected to a long-distance detour line,
As mentioned above, a delay corresponding to the zero bit occurs, and the shift register 2
5 is controlled, and the temporarily stored data is advanced by L bits and output. Therefore, the delayed data of the L focus will also be transmitted in the correct phase.

On the other hand, when switching from a long-distance detour line to a short-distance line, bits corresponding to the difference in transmission delay amount will advance, so the count of the counter 27 indicating the bit difference in that case The shift register 25 is controlled according to the contents, and the data is delayed and outputted so that it is transmitted in the correct phase.

〔Effect of the invention〕

As explained above, the present invention provides each transmitting station 2-1 to 2-
A phase difference detection control unit 4 is provided in the wired line 3-1 to 3-3.
-n to detect a change in the amount of transmission delay and control the signal phase transmitted from the transmitter 5, after setting the transmit signal phase of each transmitter station 2-1 to 2-n from the central station 1 in advance. teeth,
Since the transmitting signal phase is controlled in response to changes in the amount of transmission delay at each transmitting station 2-1 to 2-n, the transmission is delayed by switching and connecting the wired lines 3-1 to 3-n. Even if the amount of delay changes, it is possible to control the transmitting signal phases of each transmitting station 2-1 to 2-n to be the same. Therefore,
Since there is no need to provide a receiver at each transmitting station 2-1 to 2-n, 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 a transmitting station according to an embodiment of the present invention, FIG. 3 is a block diagram of a phase difference detection control section according to an embodiment of the present invention, and FIG. 5 is an explanatory diagram of bit difference detection, FIG. 6 is an explanatory diagram of a conventional example, FIG. 7 is an explanatory diagram of the signal format, and FIG. 8 is an explanatory diagram of the received signal phase. 1 is the center station, 2-1 to 2-n are transmitting stations, 3-1 to 3-n
is a wired line, 4 is a phase difference detection control section, 5 is a transmitting section, 10
is a wired line, II is a demodulator, No. 2 is a phase difference control section, 13
is a bit difference control section, 14 is an oscillator, 15 is a modulator, 16
1 is a frequency converter, 17 is a local oscillator, 18 is a bandpass filter, and 19 is a power amplifier.

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, each transmitting station (2-1 to 2-n) is equipped with a phase difference detection control unit (
4), the phase difference detection control unit (4) detects a change in the amount of transmission delay due to the wired line (3-1 to 3-n), and controls the phase of the signal transmitted from the transmitting unit (5). A transmission signal phase synchronization control method characterized in that the transmission signal phase of each transmission station (2-1 to 2-n) is synchronized.