JPH0720084B2 - Line startup method for multidirectional time division multiplex communication system - Google Patents

Description

The present invention relates to a multi-directional time division multiplex communication system for transmitting data between a master station and a plurality of slave stations in a time division multiplex system, and more particularly to a slave station. The present invention relates to a line start-up method of a multi-directional multiplex communication system in which a station adjusts data transmission timing to a master station to start a line.

[Prior Art] For example, as shown in FIG. 6, multidirectional time division multiplex communication is performed as a system for efficiently transmitting and receiving digital data between a master station 1 and slave stations 2 arranged at mutually different positions. The system has been adopted. As is well known, in this multidirectional time division multiplex communication system, as shown in FIG. 7, in the master station 1, each data S _{1 to} Sn to be transmitted to each slave station 2 of 1 to n is framed. It is incorporated in 3 and sent out. When each slave station 2 receives the signal from the master station 1, each slave station 2 extracts the data S addressed to itself, which is incorporated in the frame 3. When transmitting the data R _{1 to} Rn to the master station 1, each slave station 2 also incorporates the data R into the area of the frame 4 allocated to the master station 1 and sends it to the master station 1.

The master station 1 receives each data R _{1 to} Rn incorporated in each frame 4 sent from each slave station 2, but receives each data R ₁ received.
~ Frame length of frame 5 consisting of Rn, each data
It is necessary that the order of R _{1 to} Rn has the same frame configuration as the transmitted frame 3.

However, the distance between the master station 1 and each slave station 2 is not equal as shown in FIG. Therefore, the time required for a signal to make a round trip between the master station 1 and each slave station 2 differs. For example
At a distance of 18.8km, the signal propagation delay time is about 125μ
s, which is about 250 μs at 37.6 km. Therefore, it is necessary to adjust the transmission timing for transmitting the data R _{1 to} Rn from each child station 2 to each parent station 2. Generally, this adjustment is done in frame 3 of the signal received from master station 1.
Delay time from the detection time of the data S addressed to its own station included in
DL1 to DLn are set in each slave station 2.

FIG. 8 is a block diagram showing a schematic configuration of the master station 1 and the slave station 2 incorporating the delay time DL setting function.

The transmission data TX input to the master station 1 is the transmission multidirectional synchronization unit 10
Is converted into a unipolar signal by the bipolar / unipolar converter 10a, speed is compressed by the speed converter 10c by the synchronizing signal from the frame synchronization circuit 10b, and data from the meeting circuit 10e is added by the multiplexer 10d and scrambled. After being scrambled by the circuit 10f, it is input to the transmitter 11. Transmitter 11
In the inside, PSK (phase shift) modulation is performed on the basis of the signal from the local oscillation 11c by the PSK modulator 11d via the roll-off filter 11b after data processing by the sum calculation circuit 11a. Then, after being amplified by the power amplifier 11e, it is radiated as a radio wave.

The radiated radio wave is received by the receiver 12 of the slave station 2, amplified by the high frequency amplifier 12a, then frequency-converted by the signal from the local oscillator 12c in the mixer circuit 12b, and passed through the AGC (automatic gain adjustment) circuit 12d. Demodulated by the PSK demodulator 12e, processed by the difference calculation circuit 12f, and then received by the multidirectional synchronization unit 13
Is input to.

The reception multi-directional synchronization unit 13 detects the input reception data in synchronization with the synchronization circuit 13a, and then the de-scramble circuit 13b.
Undo the scramble process with the demultiplexer
The code is separated by 13c, the speed compressed by the speed inverse converter 13d is returned to the original value, and further, it is converted into the original bipolar signal by the unipolar / multipolar converter 13e and is taken out as the reception data RX.

Further, when transmitting data from the slave station 2 to the master station 1, the transmission data TX is input to the transmission multidirectional synchronization unit 14 as in the master station 1. Transmission data TX input to the transmission multi-directional synchronization unit 14
Is converted into a unipolar signal by the bipolar / unipolar converter 14a, and the sync signal from the frame sync circuit 14b and the sync detection circuit 13a.
The speed signal is compressed by the speed converter 14c by the speed converter 14c, data from the meeting circuit 14e is added by the multiplexer 14d, scrambled by the scramble circuit 14f, and then input to the delay circuit 14g. The delay circuit 14g delays the scrambled signal by the delay time DL set in the switch group 14h and sends the delayed signal to the next transmitter 15.

In the transmitter 15, the input signal is data-processed by the sum calculation circuit 15a and then PSK is passed through the roll-off filter 15b.
The modulator 15d performs PSK modulation based on the signal from the local oscillation 15c. Then, after being amplified by the power amplifier 15e, radio waves are radiated through the burst switch 16.

The burst switch 16 is a switch that permits radio wave emission only for the transmission time given to itself, and its release time is controlled by a command from the delay circuit 14g.

The radio wave radiated from the slave station 2 is received by the receiving section 17 of the master station 1, amplified by the high frequency amplifier 17a, then frequency-converted by the signal from the local oscillator 17c by the mixer circuit 17b, and the AGC circuit
Demodulated by the PSK demodulator 17e via 17d, and the difference calculation circuit 17f
After being subjected to data processing by, the data is input to the reception multidirectional synchronization unit 18.

The reception multi-directional synchronization unit 18 restores the input reception data to the original scramble processing by the de-scramble circuit 18a, the code separation by the de-multiplexer 18b, and the compression speed by the speed inverse converter 18c. In addition, the single-pole / double-pole converter 18d converts it to the original multi-pole signal, and the received data RX
Take out as.

In such a communication system, the above-mentioned delay time DL
Is set by the switch group 14h connected to the delay circuit 14g.
That is, the transmission data TX of the test data is applied from the slave station 2 to the transmission multi-directional synchronization unit 14, the delay time DL is set to an appropriate value by the switch group 14h, and the transmission is performed via the transmission unit 15 and the burst switch 16. To do. Then, the master station 1 receives the test data signal, determines whether or not it is the reception timing assigned to the relevant slave station 2, and notifies the person in charge of the slave station 2. If the reception timing of the master station 1 is outside the allowable range, the person in charge of the slave station 2 operates the switch group 14h again to set a different delay time DL and retransmit the test data to the master station 1.

[Problems to be Solved by the Invention] However, it takes a lot of time and labor to set the transmission timing in the slave station 2 by the above method. Therefore, much time is required until a normal line is established between the slave station 2 and the master station 1.

That is, if the slave station 2 is a fixed station, the slave station 2
If the delay time DL is accurately adjusted over time at the time of opening, it is not necessary to adjust it after that, but the slave station 2 is installed in a car or the like, moves to a specific place, and its position In the case of a semi-fixed slave station 2 that transmits data to and from the master station 1 and moves to another location when the data transmission at that location ends, the master station 1
It is necessary to set up the line between and. Therefore, in such a case, it is necessary to execute the startup work in a short time.

In addition, since the above-mentioned method sets the delay time DL with some intuition, it requires a considerably skilled person.

Further, the test data transmitted to the master station 1 to set the delay time DL is scrambled and PSK-modulated in the same manner as the official transmission data, as shown in FIG.
If the distance from the master station 1 is long, the S / N of the test data received by the master station 1 becomes low, and there is a problem that the reception timing cannot be measured accurately.

The present invention has been made in view of such circumstances,
The test data signal transmitted from the slave station to the master station is an unmodulated carrier signal, the master station measures the reception timing of the received unmodulated carrier signal without going through a demodulator, and the measurement result is fed back to the slave station. Then, the modulated test data is transmitted to the master station, and fine adjustment is performed to detect the number of errors and feed it back to the slave station. An object of the present invention is to provide a line start-up method for a multi-directional time division multiplex communication system capable of setting up a line with a master station.

[Means for Solving the Problems] In order to solve the above problems, the line startup system of the present invention is
The master station embeds each data addressed to each slave station in the reference frame by the time division multiplexing method, modulates and then sends out, and each slave station receives the signal from the master station and demodulates it to obtain the reference from the master station. The data addressed to the own station synchronized with the frame is extracted, and the data addressed to the master station is incorporated into the area assigned to the master station of the reference frame from the master station by the time division multiplexing method. From the master station, the propagation delay of the master station is adjusted and modulated, and then transmitted to the master station. At the master station, the radio waves arriving from multiple slave stations do not overlap with each other and receive as if they were transmitted from one slave station. In a division multiplex communication system, a slave station transmits an unmodulated carrier signal composed of a line spectrum that is not modulated to a master station, and the master station detects the received unmodulated carrier signal with a narrow band filter to reduce low S / Detectable by N, reception timing Accurately measure the error time from the reference reception timing for the applicable slave station and send this error time to the applicable slave station.The slave station receives the unmodulated carrier signal at the error time received from the master station. When the error time of the received unmodulated carrier signal falls within the predetermined allowable time, the master station sends a fine adjustment command to the corresponding slave station, and when the slave station receives the fine adjustment command, After modulating the test data signal of, the signal is sent to the master station, the master station demodulates the received test data signal and measures the number of errors, and this error number is transmitted to the corresponding slave station, and the slave station receives the received error. The transmission timing of the test data signal is finely adjusted based on the number.

[Operation] With such a line setup method, if synchronization from the master station to the slave station is established, a non-modulated carrier signal is transmitted from the slave station to the master station, and the master station receives the unmodulated carrier signal. The error time between the reception timing of the carrier signal and the reference reception timing is fed back to the slave station. The slave station adjusts the transmission timing based on the fed back error time. In this way, it is possible to improve the S / N by the amount of the bandwidth even when the S / N is low by detecting with the narrow band filter in the master station using the unmodulated carrier signal. Accurately complete in a short time.

In general, the improvement ratio is a value obtained by logarithmizing the ratio of the bandwidth of the filter during operation and the bandwidth of the narrow bandwidth filter.

After the rough adjustment is completed, a regular test data signal that has been subjected to various types of modulation is transmitted, and the transmission timing is finely adjusted by the number of data errors to finally obtain an accurate transmission timing.

Therefore, the time required for the entire line startup processing can be shortened. In addition, the person in charge does not need to directly adjust the transmission timing.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a master station 21 and a slave station 22 which compose a multidirectional time division multiplex communication system adopting the line startup system of the embodiment.

First, the operation of each unit in a state where the master station 21 and the slave station 22 are roughly synchronized and normal data transmission is possible will be described. That is, the transmission data input to the master station 21
The TX is added with the data from the master station control unit 24 as needed by the multiplexer 23a of the transmission multidirectional synchronization unit 23, scrambled by the scramble circuit 23b, and then transmitted by the transmission unit 25.
Is input to. The transmission data is sent to PSK in the transmission unit 25.
PSK modulation is performed by the modulator 25a, amplification is performed by the amplifier 25b, unnecessary frequencies are removed by the bandpass filter (BPF) 25c, frequency conversion is performed by the signal from the local oscillator 25e by the mixer circuit 25d, and amplification is performed by the power amplifier 25f. After that, radio waves are emitted.

The radiated radio wave is received by the reception unit 26 of the slave station 22, and is input to the PSK demodulator 26e via the high frequency amplifier 26a, the mixer circuit 26b having the local oscillator 26c, the bandpass filter 26c, and the amplifier 26d. Then, it is demodulated by the PSK demodulator 26e and input to the reception multi-directional synchronization unit 27.

The descrambling circuit 27a restores the scramble processing of the received data input into the reception multi-directional synchronization unit 27, the demultiplexer 27b performs code separation, and extracts the received data RX. The data signal that has been scrambled is the frame synchronization detection circuit 27c.
A frame synchronization signal is detected at and is input to the demultiplexer 27b and the slave station controller 28. Further, the received data RX is input to the slave station controller 28 as needed.

Further, the transmission data TX to be transmitted from the slave station 22 to the master station 21 is input to the transmission multidirectional synchronizing section 30, and the PN signal generating circuit controlled by the slave station control section 28 as needed by the multiplexer 30a.
The test data signal output from 29 is added and then input to the delay circuit 30b. The delay circuit 30b controls the transmission timing P of the data signal in response to a command from the slave station controller 28. The data signal output from the delay circuit 30b is scrambled by the scramble circuit 30c and then sent to the next transmitter 31.

In the transmitter 31, the data signal is PSK modulated by the PSK modulator 31a.
The signal is modulated, frequency-converted by a mixer circuit 31 having a local oscillator 31e via an amplifier 31b and a bandpass filter 31c, and radiated as a radio wave via a power amplifier 31f and a burst switch 31g. The burst switch 31g is a switch that releases radio wave radiation only during the transmission time given to itself, and the opening time is controlled by the slave station controller 28.

The radio wave radiated from the slave station 22 is received by the reception unit 32 of the master station 21, and demodulated by the PSK demodulator 32f via the high frequency amplifier 17a, the mixer circuit 32b having the local oscillator 32c, the bandpass filter 32d, and the amplifier 32e. Then, it is input to the reception multi-directional synchronization unit 33.

The reception multi-directional synchronization unit 33 restores the scramble processing of the input reception data by the de-scramble circuit 33a, demultiplexes the code by the de-multiplexer 33b, and extracts it as reception data RX. The received data RX is input to the bit error measuring unit 35 as necessary, the error number E included in one data (375 symbols) is measured, and the measured error number E is sent to the master station control unit 24. Is entered.

The reception signal output from the mixer circuit 32b of the reception unit 32 is input to the bandpass filter 32d and the reception timing detection unit 34. Reception timing detector 34
The received signal input to the narrowband bandpass filter 34
The unnecessary frequency component is removed by a, amplified by the amplifier 34a, and then de-energized by the duplexer 34c, and then the timing detector 34d.
Therefore, as shown in FIG. 5, the reception timing Q of the first one symbol (1 bit data) of the reception signal is set as the error time P _A from the reference timing Q _{S which is} assigned to each slave station 22 in advance. It is detected and sent to the master station controller 24. The error time P _A has a duration of one symbol as one unit. That is, when the error time P _A is around 1,
The data moves back and forth by 1 bit.

Note that, in FIG. 1, a double pole / single pole converter, a speed converter, a roll-off filter, etc. are omitted.

The master station control unit 24 and the slave station control unit 28 are composed of, for example, a microcomputer, and execute a line startup process between the master station 21 and the slave station 22 according to a control program stored in a storage unit (not shown). To do. 2 and 3
The figure is a flow chart showing the processing contents of the slave station control unit 22 and the master station control unit 21 when the line is activated. The contents of the round-up start-up process will be sequentially described below with reference to the flowcharts. It is assumed that the general synchronization between the master station 21 and the slave station 22 is established in advance.

First, in FIG. 3, in the master station 21, when the number of the slave station 22 for which the transmission timing (delay time DL) is to be set is input from the keyboard in S (step) 1, the corresponding slave station in S2. Error time P _A for 22 is initial value P _A ＝
Send as 0.

Further, in the slave station 22, as shown in FIG. 2, when an approximate transmission timing P ₀ is input from the keyboard in S3, the transmission timing P ₀ is temporarily set in the transmission timing memory (P = P ₀ ). Note that this rough transmission timing P ₀ is a value that can be easily calculated from the rough distance to the master station 21 and the radio wave transmission speed.

Then, in S4, the operations of the scramble circuit 30c and the PSK modulation circuit 31a are stopped. That is, the output signal of the delay circuit 30b passes through the scramble circuit 30c and the PSK modulation circuit 31a and is input to the amplifier 31b. Next, at S5, burst switch 31g
To reduce the burst length. That is, the transmitter
As shown in Fig. 4, the width of the test signal sent to the 31 is set to a signal width (279 μs, 279 symbols) shorter than the signal width of a normal data signal (375 μs, 375 symbols), and 48 μs (48 A non-signal area for a symbol). The reason why the burst is shortened is that it does not interfere with the communication of other slave stations that have already started up.

Then, if the command is input from the master station 21 in S6 and the transmission timing change command specifies the error time P _{A in} S7,
Error time P _{A for} the transmission timing P of the transmission timing memory
Is added (corrected). Then, in S8, the corrected transmission timing P is set in the delay circuit 30b. Then, at P9, when the test data signal whose signal width has been shortened is applied to the multiplexer 30a via the PN signal generator 29, this test data signal is transmitted by the delay circuit 30b at the transmission timing P described above.
Therefore, it is sent to the transmission unit 31. As described above, since the operations of the scramble circuit 30c and the PSK modulation circuit 31a are stopped, the signal radiated via the burst switch 31g is the unmodulated carrier signal shown in FIG.

When the master station control unit 24 receives the unmodulated carrier signal from the slave station 22 in S10 of FIG. 3, in S11, the reference of the reception timing Q detected by the timing detector 34d of the reception timing detection unit 34 Read the error time P _A from timing Q _S. When the read error time P _A shown in FIG. 5 exceeds 2, the error time P _A is sent again to the corresponding slave station 22 as a timing change command in S13.

In FIG. 2, the slave station control unit 28 of the slave station 22 that has received the timing change command P _A again in S6 corrects the transmission timing P of the transmission timing memory with P _A again, and again receives the unmodulated carrier signal. Is sent.

When the error time P _A of the reception timing Q of the unmodulated carrier signal received again in S12 of FIG. 3 becomes 2 (2 symbols) or less, the rough adjustment processing of the transmission timing is completed,
In S14, a fine adjustment command is sent to the corresponding slave station 22.

Slave station 2 that received the fine adjustment command from master station 21 in S15 of FIG.
The slave station control unit 28 of the second scramble circuit 30c, PS
The operation of the K modulator 31a is returned to the normal state, and the burst length is returned to the normal 375 μs (375 symbols) in S17. Then, 2 is added to the transmission timing P of the transmission timing memory, and the transmission timing P after the addition is set in the delay circuit 30b in S18. Then, in S19, the PN signal generation circuit
It controls 29 to send out a predetermined test data signal containing data for 375 symbols. Then, this test data signal is scrambled by the scramble circuit 30c, PSK-modulated by the PSK modulator 31a, and radiated in the same format as the regular transmission data.

In S20 of FIG. 3, when the test data signal of the regular format is received from the slave station 22, not the reception timing detection unit 34 but the regular reception unit 32 and the de-scramble circuit 3
3a, the received data RX of the test data signal is obtained in a normal state via the demultiplexer 33b, the error number E contained in this test data signal is measured by the bit error measuring unit 35, and the measured error number E is Send to slave station 22 in S21.

Slave station 2 that received the error count E from the master station 21 in S22 of FIG.
The slave station control unit 28 of No. 2 judges in S23 whether or not the error number E is less than or equal to the allowable error number. Compared to,
The transmission timing P is moved by (1/72) in the direction in which the number of errors E decreases. Then, returning to S18, the transmission timing P after the movement is set in the delay circuit 30b,
The test data signal in the normal format is transmitted again. In the case of the first error count E, the transmission timing P is unconditionally added by (1/72).

In FIG. 3, the master station 21, which has received the test data signal again from the slave station 22, measures the error number E again and transmits it to the slave station 22.

When the number of errors E received in S23 of FIG. 2 becomes less than the allowable number of errors, the self-ID information is sent to the master station 21 together with the fine adjustment end information in S25.

In FIG. 3, the master station 21, which has received the ID information from the slave station 22 in S26, sets the ID information in a predetermined area of the transmission format.

In the line finishing method of such a multidirectional time division multiplex communication system, first, the slave station 22 sets, for example, a rough transmission timing P ₀ obtained by a simple calculation in the delay circuit 30b, and the master station 21 Establish synchronization between the two. Then, after enabling data transmission / reception with the master station 21, the master station 21 sends a rough adjustment command and the slave station 22 sends an unmodulated carrier signal. In this way, only by first inputting the rough transmission timing P ₀ to the slave station 22 and activating the master station 21, the transmission timing P is automatically set between the master station 21 and the slave station 22 thereafter. Set to the optimum value. Therefore, the burden on the operator can be significantly reduced. Also, the operator does not have to be an expert as in conventional methods.

Further, when the transmission timing P is adjusted, the adjustment is performed in two steps: coarse adjustment using an unmodulated carrier signal and fine adjustment using a normally modulated test data signal. Therefore, compared with the conventional method that uses only the fine adjustment method from the beginning, the number of test signals and test results exchanged between the slave station 22 and the master station 21 can be significantly reduced, and the adjustment process can be performed efficiently. Can be executed.

Further, as a test signal for performing the coarse adjustment, using an unmodulated carrier signal that has not been scrambled or modulated by the scramble circuit 30c or the PSK modulation circuit 31a,
And the master station 21 has a de-scramble circuit 33a and a PSK demodulation circuit.
The reception timing detector 34 directly detects the reception timing Q without going through 32f. Then, in the reception timing detection unit 34, since it is only necessary to receive the unmodulated carrier signal, the bandpass filter 34a can be set to a narrow band that allows only the carrier signal to pass, and the reception accuracy of the unmodulated carrier signal is improved, The S / N of the received signal can be greatly improved. Therefore, the measurement accuracy of the reception timing Q in the timing detector 34d can be greatly improved. In particular, when the distance between the master station 21 and the slave station 22 is large and the S / N of the received test signal is low, the effect of using the unmodulated carrier signal is very large.

In the embodiment method, after setting the necessary data described above in the master station 21 and the slave station 22 and activating them, one frame
One transmission data is composed of 375 symbols for 3 ms, and an error occurs in the transmission of various commands and data from the master station 21 to the slave station 22 once every two frames, and the setting accuracy of the transmission timing P is one symbol. The time required to set to (1/72) was 24 ms for coarse adjustment and 1740 ms for fine adjustment, and the total time was about 2 seconds. This is much shorter than the conventional manual method by a person in charge.

[Effects of the Invention] As described above, according to the line setup method of the multidirectional time division multiplex communication system of the present invention, the test data signal transmitted from the slave station to the master station is an unmodulated carrier signal, and the master station The reception timing of the received unmodulated carrier signal is measured by improving the S / N with a narrow band filter without passing through the demodulator, and the rough adjustment to feed back the measurement result to the slave station and the modulated test data to the master station. Two-step adjustment is carried out, which is fine adjustment by transmitting and detecting the error number and feeding it back to the slave station. Therefore, the line start-up process between the slave station and the master station can be performed quickly and accurately with only a simple operation.

[Brief description of drawings]

1 to 5 show a line setup system according to an embodiment of the present invention, and FIG. 1 shows a master station and a slave station of a multidirectional time division multiplex communication system to which the method of the embodiment is applied. 2 and 3 are flowcharts showing the operation, FIGS. 4 and 5 are time charts showing the operation, and FIG. 6 is a schematic diagram showing a general multidirectional time division multiplex communication system. Fig. 7 is a diagram showing the transmission timing between the master station and the slave station, Fig. 8 is a block diagram showing the master station and the slave station to which the conventional startup method is applied, and Fig. 9 is PSK-modulated. It is a general data signal waveform diagram. 21 …… Master station, 22 …… Slave station, 23,30 …… Transmission multi-directional synchronization section, 24 …… Parent station control section, 25,31 …… Transmission section, 26,32 …… Reception section, 27,33 ...... Reception multi-directional synchronization block, 28 ...... slave station control block, 34 ...... Reception timing detection block, 35 ...... Bit error measurement block.

Claims (1)

[Claims] 1. A master station embeds each data addressed to each slave station in a reference frame by a time division multiplexing method, modulates the data, and then transmits the data. Each slave station receives and demodulates a signal from the master station. From the master station, the data addressed to the master station synchronized with the reference frame from the master station is extracted, and the data addressed to the master station is embedded in the area assigned to the master station in the reference frame from the master station by time division multiplexing. After the propagation delay of the slave station and the slave station is adjusted and modulated, it is sent to the master station. In the master station, the radio waves arriving from many slave stations do not overlap with each other, as if they were transmitted from one slave station. In a multi-way time division multiplex communication system for receiving, the slave station transmits an unmodulated carrier signal consisting of a line spectrum that is not modulated to the master station, and the master station receives the unmodulated carrier signal by a narrow band filter. Low S / N by detecting at Detectable, measuring the error time between the reception timing and the predetermined reference reception timing for the corresponding slave station systematically, and sending this error time to the corresponding slave station, the slave station from the master station The transmission timing of the non-modulated carrier signal is adjusted by the received error time, and when the error time of the received non-modulated carrier signal falls within a predetermined allowable time, the master station sends a fine adjustment command to the corresponding slave station, When the slave station receives the fine adjustment command, it modulates a predetermined test data signal and sends it to the master station, and the master station demodulates the received test data signal to measure the number of errors, and the error number To the corresponding slave station, and the slave station finely adjusts the transmission timing of the test data signal based on the number of received errors.