JPH0955698A - Phase compensation system for multiple address transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain phase compensation for multiple address transmission even when plural transmission stations are in multi-drop connection to a central controller. SOLUTION: Transmission stations 20a to 20n are in multi-drop connection to a central controller 1 by a transmission line 5. The central controller 1 sends a delay measurement signal S6 to the transmission station 20a through the transmission line 5 and receives a reflected signal S5 from a line control section 3a of the transmission station 20a to measure a transmission delay D1 and calculates a setting delay Dxa to eliminate differences from the transmission delays D1 to Dn among the transmission stations 20a to 20n based on the transmission delay D1 and sends the information S6 to the transmission station 20a. Upon receipt of the information S6, the transmission station 20a sets the setting delay Dxa to a passing circuit of a multiple address transmission signal S3 in the line control section 3a. Similarly the delay Dxn is set to the other transmission stations 20b to 20n and phase compensation of radio signals S1a to S1n for multiple address transmission is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase compensation method for a broadcast transmission system in which broadcast transmission signals sent from a central control unit are simultaneously broadcast as radio signals from a plurality of transmission stations. The present invention relates to a phase compensation method for a broadcast transmission system in which a multi-drop connection is made to the central controller.

[0002]

2. Description of the Related Art In this type of conventional broadcast transmission system,
A plurality of transmitting stations are multi-drop connected to the central control unit via a 4-line transmission line consisting of a 2-line downlink and a 2-line uplink. The lengths of the transmission lines between the central controller and each of the transmitting stations are usually different from each other. Therefore, if the broadcast transmission signal distributed from the central control station is transmitted as it is from each of the transmission stations, a signal phase difference (radio wave interference) occurs between the broadcast transmission signal and the same broadcast transmission signal transmitted by the adjacent transmission station. Therefore, it is difficult for a terminal device existing within the range of receiving the broadcast transmission signals from a plurality of transmission stations to read the broadcast transmission signals accurately, and there is a problem that the reception rate of the broadcast transmission signals decreases. It was

On the other hand, another type of broadcast transmission system is disclosed in Japanese Patent Application Laid-Open No. 5-145469 (title of the invention: mobile communication system). FIG. 3 shows a configuration diagram equivalent to the disclosed broadcast communication system.

In this broadcast communication system, the central control unit 6
0 and a plurality of transmitting stations 80a, 80b and 80c are connected by different transmission lines 70a, 70b and 70c, respectively. The central controller 60 is an M / D 62a, 6
The broadcast transmission signals respectively modulated by 2b and 63c are sent to the transmission lines 70a, 70b and 70c. The transmission stations 80a, 80b, and 80c include transmission lines 70a, 70b.
b and 70c, the broadcast transmission signals from the M / D 81a, 8
After demodulating with 1b and 81c respectively, the transmitter 82
a, 82b and 82b are respectively converted into radio signals and transmitted from the built-in antenna.

Here, the central controller 60 controls the transmission line 7
Even if the transmission delay amounts due to 0a, 70b, and 70c are different from each other, the variable delay circuits 61a, 61b, and 61c whose delay amounts are set so that the phases of the radio signals transmitted from the transmission stations 80a, 80b, and 80c are equal are provided. It is built in before the M / Ds 61a, 61b and 61c. As described above, the central controller 60 determines the difference between the variable delay circuits 42a, 42b, 4 even when the transmission delay amounts of the transmission lines 41a, 41b, 41c are different from each other.
It could be corrected by 2c. That is, the central controller 60
Determines in advance the total delay amount Dt from the transmission of the broadcast transmission signal to the transmission of the radio signal from the transmitting station, and the total delay amount Dt and the transmission by the transmission lines 41a, 41b and 41c. The variable delay circuit 42 calculates the difference from the delay amount.
a, 42b, and 42c, respectively. As a result, the broadcast transmission signal is distributed at the point P of the central control device 60, and after a total delay amount Dt, the transmission stations 80a and 80b are transmitted.
And 80c are converted into a radio signal in which phase synchronization is established and transmitted.

[0006]

However, in the disclosed phase compensation method of the broadcast transmission system, since the phase compensation of the broadcast transmission signal is performed by the variable delay circuit provided in the central controller, a plurality of transmission signals are transmitted. In the case of a broadcast transmission system in which stations are connected to a central control unit in a multi-drop manner, there is a drawback in that the phase of broadcast transmission signals for each of the transmitting stations cannot be adjusted because the transmission lines connected are the same.

Therefore, the present invention, in a broadcast transmission system in which a plurality of transmission stations are connected to a central control unit in a multi-drop manner, has an appropriate phase compensation so that a radio signal transmitted from each of the transmission stations can be broadcast. It is an object of the present invention to provide a phase compensation method for a broadcast transmission system that can provide the signal.

[0008]

A phase compensation method for a broadcast transmission system according to the present invention is a center for transmitting a broadcast transmission signal to a 4-line transmission line consisting of 2-line downlinks and 2-line uplinks. A phase compensation method for a broadcast transmission system, comprising: a control device; and a plurality of transmission stations that are multi-drop connected to the central control device by the transmission line and that convert the broadcast transmission signal into a radio signal and broadcast the same. Then, the central control unit transmits a delay measurement signal to each of the transmitting stations through the transmission line and receives a return signal of these delay measuring signals to receive a transmission delay amount with each of the transmitting stations. And a set delay amount for calculating the set delay amount for eliminating the difference in the send delay amount between each of the transmitting stations in response to the measured send delay amount. Emotion And a transmission delay amount control means for sending to each of the corresponding transmission stations, each of the transmission stations, to the transmission line, the delay measurement signal from the central control unit received via the transmission line. A delay measurement signal folding means for folding back, and a variable delay means for receiving the information of the set delay amount and setting the set delay amount in the pass circuit of the broadcast transmission signal are provided.

The phase compensation method of the broadcast transmission system is as follows:
The transmission delay amount measuring means sends back the return control signal to each of the transmitting stations individually, and the return line setting control means, and when receiving the return line setting signal from the transmitting station, sends out the delay measuring signal. A delay measurement signal transmitting / receiving unit for receiving a return signal of the delay measurement signal; and a transmission delay amount measuring unit for measuring a delay time from the transmission of the delay measurement signal to the reception of the return signal of the delay measurement signal. The delay amount control means sends the set delay amount calculating means for calculating the set delay amount based on the measured transmission delay amount, and the delay amount setting signal, which is information on the set delay amount, to the corresponding transmitting station, respectively. A delay time setting control means for receiving the return control signal, and the signal return means of the transmitting station receives the return control signal through the downlink. A return line is set to return the extension measurement signal to the central control unit through the upstream line, and the variable delay unit cancels the setting of the return line when the delay amount setting signal is received and outputs the signal from the central control unit. Can be configured to further include a signal line setting means for sending to the pass circuit of the broadcast transmission signal.

[0010]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a system configuration diagram showing an embodiment of the present invention.

The broadcast transmission system of FIG. 1 comprises a central control unit 1 and n (n is a plurality) transmitting stations 20a, 20b ,.
0n and a transmission line 5 for connecting each of the transmitting stations 20a to 20n to the central control unit 1 in a multi-drop manner. When the central controller 1 sends out the broadcast transmission signal S3 from the two downlink lines of the transmission line 5, each of the transmission stations 20a to 20n receives the broadcast transmission signal S3 received from the transmission line 5 as a radio signal S1.
, S1b, ..., S1n, respectively, and broadcast transmission. The transmission line 5 transmits the signals from the transmission stations 20a to 20n to the central control device 1 by an up line composed of two lines. In addition, from the central controller 1 to the transmitting stations 20a, 20b,
The lengths of the transmission lines 5 up to 20n are in ascending order, and are L1, L2, ..., Ln, respectively. The line lengths L1, L2, ..., Ln of the transmission line 5 generate transmission delay amounts D1, D2 ,. Also, the broadcast transmission signal S at the transmission stations 20a, 20b, ..., 20n.
The transmission delay time from the reception of No. 3 to the transmission of the radio signals S1a to S1n may have substantially the same delay time D0.

The central controller 1 generates a broadcast transmission signal S3, a loopback control signal S4, a delay measurement signal S6a, and a delay amount setting signal S6b (information S6a and S6b are included in the signal S6) including information on the set delay amount. And a signal transmission unit for transmitting the signal to the transmission line 5, and the folded line setting signal S7 and the delay measurement signal S6 from each of the transmission stations 20a to 20n.
2D, 2D1, 2D2, ..., 2D by the signal receiving unit that receives the loopback signal S5 of a and the transmission line 5 from the transmission of the delay measurement signal S6a to the reception of the loopback signal S5.
In order to synchronize the phases of the radio signal S1a to S1n transmitted from each of the transmitting stations 20a to 20n in response to the transmission delay amount measuring unit that measures n with the measured transmission delay amounts 2D1 to 2Dn, one-way The transmission delay amounts D1 to Dn include a setting delay amount calculation unit that calculates the setting delay amount that eliminates differences between the transmission delay amounts D1 to Dn. Each component of the central control unit 1 is composed of a microprocessor circuit and a digital circuit.

Further, the transmitting stations 20a, 20b, ..., 20n
, 3n for processing the signals S3, S4 and S6 from the central controller 1, respectively.
, 3n from the line control devices 3a, 3b, ..., 3n are transmitted as radio signals S1a, S.
1b, ..., S1n respectively converted to antennas 4a, 4
Transmitters 2a, 2 for transmitting from b, ..., 4n respectively
b, ..., 2n. Transmitting stations 20a, 20b, ...
Since all of the 20n have the same configuration, the transmitting station 20
a will be described.

When the line control device 3a of the transmitting station 20a receives the loopback control signal S4 from the central control device 1 via the downlink of the transmission line 5, it receives the delay measurement signal S6a received from the central control device via the downlink. Transmission line 5
The turn-back line is set to the central control unit 1 through the ascending line and the turn-back line setting signal S7 is sent to the central control unit 1. Thereafter, when the delay measurement signal S6a is sent from the central controller 1, the line controller 3
a returns the return signal S5 of the signal S6a to the central control unit 1. Further, when receiving the delay amount setting signal S6b from the central control device 1, the line control device 3a receives the transmitter 2a.
A delay amount corresponding to this signal S6b is set in the passage circuit of the broadcast transmission signal S3 to the. At the same time, the line control device 3a releases the setting of the folded line and supplies a circuit for supplying the broadcast transmission signal S3 from the central control device 1 to the transmitter 2a via the passage circuit for the broadcast transmission signal S3. To construct.

Next, the phase compensation operation in the broadcast transmission system of FIG. 1 will be described.

The signal transmission unit of the central control unit 1 first transmits the loopback control signal S4 (S4a) to the transmission station 20a. When the line control device 3a of the transmitting station 20a receives the loopback control signal S4a via the downlink of the transmission line 5, the line control device 3a receives the delay measurement signal S6a received from the central control unit 1 through the downlink through the uplink of the transmission line 5. A turn-back line is set in the control unit 1 and a turn-back line setting signal S7 is sent to the central control unit 1 via the upstream line. In the central controller 1, when the signal receiving unit receives the signal S7, the signal transmitting unit sends the delay measurement signal S6a to the transmitting station 20a, and the transmission delay measuring unit starts measuring the transmission delay amount D1. Line controller 3
a returns the return signal S5 of the delay measurement signal S6a to the central controller 1. The signal receiving unit returns the return signal S5.
When receiving the transmission delay measurement signal, the transmission delay measurement unit receives the delay measurement signal S6.
1 of the time D from the transmission of a to the reception of the return signal S5
/ 2 is measured as the transmission delay amount D1 for the transmitting station 20a.

Upon receipt of this transmission delay amount D1, the set delay amount calculation section of the central control unit 1 causes the central control unit 1 and the transmitting station 2 to operate.
Setting delay amount Dx for canceling the difference existing between transmission delay amounts D1 to Dn with each of 0a to 20n.
Is calculated. Now, from the transmission of the broadcast transmission signal S3 by the central control unit 1 to the radio signal S by the transmission stations 20a to 20n.
The maximum delay amount until the transmission of 1 is (Dn + Do). D
Since 0 is the same for all transmitting stations 20a to 20n, the setting delay amount Dxa to be set in the transmitting station 20a is (Dn-D
1 + α). However, α is a value determined in consideration of various fluctuation errors.

The signal transmitting section of the central controller 1 transmits the delay amount setting signal S6b containing the information of the set delay amount Dxa to the transmitting station 20a via the transmission line 5. Upon receiving this delay amount setting signal S6b, the line control device 3a causes the passage circuit of the broadcast transmission signal S3 to the transmitter 2a to pass this signal S6b.
The delay amount Dxa corresponding to is set. At the same time, the line control device 3a cancels the setting of the return line and changes the broadcast transmission signal S3 from the central control device 1 to the broadcast transmission signal S.
A circuit for supplying to the transmitter 2a via the passage circuit of No. 3 is constructed.

Broadcast transmission signal S3a to the transmitting station 20a
After the setting of the delay amount Dxa of the central processing unit 1 is completed, the central control device 1 performs a procedure similar to that described above for all the remaining transmitting stations 20b,
, 20n, the signal delay amounts Dxb, ..., Dxn for the broadcast transmission signal S3 are set. As a result, phase compensation is executed for all the transmitting stations 20a, 20b, ..., 20n. Therefore, the broadcast transmission signal S3 transmitted from the central controller 1 after executing the above phase compensation is
After (Dn + α) time, all the transmitting stations 20a, 20b,
, 20n are simultaneously broadcasted as radio signals S1a, S1b, ..., S1n.

FIG. 2 is a detailed view of the line control device 3a and the transmission line 5 used in this embodiment.

When the loopback control signal S4a is received from the central control unit 1 via the down line 51 of the transmission line 5, the line control unit 35 of the line control unit 3a uses the control signal S4a as a control signal S33 for SIO (serial I / O). O) 36 to CPU 34. The CPU 34 controls the control signal S33.
Is determined to be a loopback line setting control signal sent from the central control unit 1, and the control signal S35 sets a line for looping back the delay measurement signal S6a from the downlink 51 of the transmission line 5 to the uplink 52 as a loopback signal S5. To do. Next, the CPU 34 sends out the return line setting signal S34 via the SIO 36, and outputs the return line setting signal S7 obtained by passing the signal S34 through the line control unit 35 to the up line 5.
2 to the central controller 1. After that, when the delay measurement signal S6a is sent from the central control unit 1 via the downlink 51, the line control unit 35 causes the delay measurement signal S6a to be transmitted.
6a is returned to the upstream line 52 as a return signal S5. Next, when the line control device 3a receives the delay amount setting signal S6b including the information of the setting delay amount Dxa from the central control device 1, the signal S6b is passed to the CPU 34 through the SIO 36. The CPU 34 stores the set delay amount Dxa in the register 33.
The register 33 sets the set delay amount Dxa in the variable delay circuit 32.

When the delay amount Dxa is set in the variable delay circuit 34, the CPU 34 releases the setting of the folded line of the line control circuit 34 by the control signal S35. After that, when receiving the broadcast transmission signal S3 from the central controller 1, the line controller 35 sends the broadcast transmission signal S3 to the variable delay circuit 32 as a signal S32. The variable delay circuit 32 uses the broadcast transmission signal S
Broadcast transmission signal S2 obtained by delaying 32 by delay time Dxa
a is supplied to the transmitter 2a via the switch 31. Until the set delay amount Dxa is set in the register 33, the switch 31 is off-controlled by the control signal S31 from the CPU 34, and the transmitter 2a does not send a radio signal.

As described above, by providing the variable delay circuit 32 in the line control device 3a in front of the transmitter 2a, the transmission delay of the broadcast transmission signal S3 in each unit of the transmission stations 20a, 20b, ..., 20n. It is possible to adjust the amount, and the transmitting station 20a-
Even when 20n is multi-drop connected to the central controller 1, the phase compensation between the transmitting stations 20a to 20n is possible.

[0025]

As described above, according to the present invention, the central control device transmits the delay measurement signal to each of the transmitting stations through the transmission line for the multi-drop connection and receives the folding signal of these delay measurement signals. A set delay amount for measuring the transmission delay amount with each of the transmitting stations and canceling the difference in the transmission delay amount with each of the transmitting stations in response to the measured transmission delay amount. For each of the transmission stations, and each of the transmission stations transmits the delay measurement signal from the central control device received through the transmission line. Since the setting delay amount is returned to the line and is set in the pass circuit of the broadcast transmission signal by receiving the information of the setting delay amount, each of the transmitting stations is multi-drop connected to the central controller. Even Serial there is an effect that a radio signal corresponding to the broadcast transmission signal can be transmitted phase difference without from each respective said transmission stations.

In general, a broadcast transmission system uses a dedicated transmission line for broadcast transmission signals. Therefore, if the number of transmission stations increases, the cost of laying this transmission line becomes enormous. Therefore, it is obvious that the cost of laying this transmission line can be greatly reduced if a multi-drop connection broadcast transmission system can be adopted. As described above, the present invention can enable multi-drop connection in a broadcast transmission system with a simple configuration and control procedure, so that there are immeasurable economic effects.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a phase compensation method of a broadcast transmission system according to the present invention.

FIG. 2 is a detailed view of a line control device 3a and a transmission line 5 used in this embodiment.

FIG. 3 is a block diagram of a conventional broadcast transmission system.

[Explanation of symbols]

 1 central control device 2a, 2b, 2n transmitter 3a, 3b, 3n line control device 4a, 4b, 4n antenna 5 transmission line 20a, 20b, 20n transmission station 31 switch 32 variable delay circuit 33 register 34 CPU (control unit) 35 Line control unit 36 SIO (serial I / O) 51 Down line 52 Up line

Claims (2)

[Claims] 1. A central control device for sending a broadcast transmission signal to a four-line transmission line consisting of two downward lines and two upward lines, and a multi-drop connection to the central control device by the transmission lines. A phase compensation method of a broadcast transmission system comprising: a plurality of transmitting stations for converting the broadcast transmission signal into a radio signal and transmitting the broadcast signal, wherein the central control device provides a delay measurement signal through the transmission line. Transmission delay amount measuring means for transmitting to each of the transmitting stations and receiving a return signal of these delay measurement signals to measure a transmission delay amount between each of the transmitting stations, and the measured transmission delay amount. In response to the transmission delay amount control means for calculating the set delay amount for eliminating the difference in the transmission delay amount between each of the transmitting stations and transmitting the set delay amount information to the corresponding transmitting station. When Each of the transmitting station, each of the delay measurement signal folding means for folding back the delay measurement signal from the central control unit received via the transmission line to the transmission line, and receiving information on the set delay amount. A phase compensation method for a broadcast transmission system, comprising: variable delay means for setting the set delay amount in a pass circuit for the broadcast transmission signal. 2. The transmission delay amount measuring means outputs the return control signal to each of the transmitting stations individually, and the return line setting control means receives the return line setting signal from the transmitting station. A delay measurement signal transmission / reception means for transmitting the return signal of the delay measurement signal and a transmission delay amount measuring means for measuring the delay time from the transmission of the delay measurement signal to the reception of the return signal of the delay measurement signal. The transmission delay amount control means, the setting delay amount calculation means for calculating the setting delay amount based on the measured transmission delay amount, and the delay amount setting signal corresponding to the information of the setting delay amount corresponding A delay time setting control means for sending to each transmitting station, and when the signal folding means of the transmitting station receives the folding control signal, it passes through the downlink. A delay line for returning the delay measurement signal received by the central control unit through the uplink, and the variable delay unit cancels the setting of the return line when the delay amount setting signal is received, and the central control unit 2. The phase compensation method for a broadcast transmission system according to claim 1, further comprising signal line setting means for sending a signal from the broadcast transmission signal to a passage circuit for the broadcast transmission signal.