JPH01268299A - Transmitting amplitude control system for communication network - Google Patents

Abstract

PURPOSE:To normally receive a high speed burst signal from respective slave stations, whose transmission loss is respectively different, without fail in a master station without using a high speed automatic gain control circuit by adjusting the transmitting level of a self-station transmitting level control circuit in correspondence to the transmission loss value, which is detected by a transmission loss detecting circuit, in the respective slave stations. CONSTITUTION:The signal transmission loss between the self-stations and a master station 51 is known for respective slave stations 521 to 52n and in correspondence to this value, the transmitting level of a transmitting level control circuit 56 in a self-station transmitting circuit 55 is adjusted. In the receiving end of the master station 5, the receiving amplitudes of transmitting signals, which come from the respective slave stations 521 to 52n, are caused to be an almost same value. Thus, since the burst-shaped transmitting signals from the respective slave stations 521 to 52n, whose transmission loss is respectively different, are automatically arranged to an almost same signal level in the receiving end of the master station 51, even when a transmitting speed goes to be high, the transmitting signals from the respective slave stations 521 to 52n can be received without fail in the master station 51 without using the high speed automatic gain control circuit.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a transmission amplitude control method in a communication network such as L, AN or 15DN.

The purpose of this system is to allow the main station to correctly receive high-speed burst signals from slave stations with different transmission losses without using a high-speed automatic gain control circuit.

In a communication network where a master station and multiple slave stations are connected via a transmission line, a transmission loss detection circuit is provided to detect signal transmission loss in the transmission line.The transmission circuit of each slave station variably adjusts its own transmission level. A transmission level control circuit is provided, and each slave station is configured to adjust the transmission level of its own transmission level control circuit in accordance with the transmission loss value detected by the transmission loss detection circuit.

[Industrial application field]

The present invention relates to a transmission amplitude control method in a communication network such as a LAN (Local Area Network) or an I5DN (Integrated Digital Service Network).

[Conventional technology]

In LAN, 15DN, etc., there is a communication network in which a master station and a plurality of slave stations are connected in the form of a bus. FIG. 8 is a diagram showing such a bus-type communication network. In the figure, 1 is a main station, 21 to 2.1 are slave stations, and 3 is a common transmission line.The common transmission line 3 is a down line 31 for transmitting data from the main station 1 to each slave station 21 to 2n. and each subordinate station 2. .about.2n to the main station 1.

In such a bus-type communication network, each of the slave stations 21 to 2n has a different transmission path distance from the master station 1, and therefore each slave station 2. The block signals sent from ~2n toward the main station 1 are subjected to different transmission losses B and ~Bn on the uplink line 32, respectively.

Therefore, at the uplink receiving end of the master station I, each slave station 2. The received pulse amplitudes of the block signals from ~2n differ from each other. If the reception amplitude difference between the block signals from each of the slave stations 21 to 2n becomes large, the receiving circuit of the main station 1 may not be able to read the received data.

There is a possibility that noise may be mistaken for data.

For this reason, when the main station takes in the block signals from each of the slave stations 21 to 2n, it is necessary to keep the received amplitude level constant for all slave stations 2] to 2n. This is for each subordinate station 2. The same applies to reception at ~2n.

FIG. 9 is a diagram showing a conventional system in which the received amplitude level at the main station 1 and the slave stations 21 to 2n is kept constant. In this conventional system, master station 1 and slave station 2. An automatic gain control circuit 15.22 is provided in the receiving circuit of .about.2n.

That is, the main station 1 has a driver 11. Receiver 12° Receiver 12 receives slave station transmission signals from slave stations 21 to 2n via uplink 32
It is configured to include an automatic gain control circuit 15, etc., which adjusts the output of the circuit to a constant value. Further, each of the slave stations 21 to 2n has a receiver 21 . Receiver 2
An automatic gain control circuit 22 that adjusts the output of 1 to two constant values. It is configured to include a driver 24 and the like that sends a slave station transmission signal to the up line 32.

FIG. 10 is a block diagram showing the configuration of the automatic gain control circuit 15, and the automatic gain control circuit 22 has exactly the same configuration. As shown, a variable gain amplifier 151,
Peak detection! 5 (or average power detector) 152.
It is configured to include a comparator 153. The signal input to the main station 1 is input to the variable amplifier 151 of the automatic gain control circuit 15 via the receiver 12, and the output of this variable amplifier 151 is sent inside the main station as a received signal.

The output of the variable amplifier 151 is input to a peak detector 152 to detect the peak value of the signal. This peak value is compared with a reference voltage Vref by a comparator 153, and if the detected peak value Vp is larger than the reference voltage Vref, the output of the variable amplifier 151 is reduced.
Adjust the gain. Also, the detected peak value Vp is the reference voltage Vr
If it is smaller than ef, the gain of the variable amplifier 151 is adjusted so that the output of the variable amplifier 151 becomes larger. As a result,
The output amplitude of the variable amplifier 151 approaches the reference voltage V ref and maintains a constant value.

[Problem to be solved by the invention]

It is assumed that high-speed burst block signals as shown in FIG. 11 are transmitted and received through this bus-type communication network. This block BL includes preamble PR, delimiter DL,
It consists of information INFO, and a guard time G is inserted between blocks BL, -BLn sent from each slave station 21-2n.

Now, the blocks BL from each slave station 21 to 2n.

When ~BLn is received by main station 1, each block BL, ~
Since the reception amplitudes of BLn are different from each other, the automatic gain control circuit 15 of the main station 1 controls each block BL1 to BLn.
It is necessary to perform automatic gain control so that the received amplitude value becomes constant every n. In this case, in order to receive the information INFO normally, it is necessary to complete automatic gain control during the preamble PR period added as a timing signal. Generally, it is desirable to set the preamble PR as short as possible in order to improve transmission efficiency.

Therefore, when handling high-speed burst signals in a communication network, the automatic gain control circuit 15 of the main station 1 is required to operate at a very high speed. However, it is generally technically difficult to construct such a high-speed automatic gain control circuit, and even if it were possible, the manufacturing cost would be too high to put it into practical use.

Therefore, an object of the present invention is to enable a main station to normally receive high-speed burst signals from slave stations having different transmission losses without using a high-speed automatic gain control circuit without error.

[Means to solve problems]

FIG. 1 is a principle block diagram according to the present invention.

In the transmission amplitude control method according to the present invention, in a communication network in which a main station 51 and a plurality of slave stations 521 to 52n are connected via a transmission line 53, a transmission loss detection circuit 54 that detects a signal transmission loss in the transmission line 53 is configured. Master station 51 or each slave station 52.
52n, the transmission circuit 55 of each slave station 521 to 52n is equipped with a transmission level control circuit 56 that variably adjusts its own transmission level, and each slave station 521 to 52n is provided with a transmission level control circuit 56 that variably adjusts the transmission level of its own station. It is configured to adjust the transmission level of the own station transmission level control circuit 56 according to the value.

[Effect]

Each slave station 52. ~52n learns the signal transmission loss between the local station and the main station detected by the transmission loss circuit 54, adjusts the transmission level of the transmission level control circuit 56 of the local station transmission circuit 55 according to this value, and thereby At the receiving end of the master station, the reception amplitudes of the transmission signals arriving from each slave station are made to have approximately the same value.

〔Example〕

The present invention will be described in detail below with reference to nine drawings.

A communication network implementing a transmission amplitude control method as an embodiment of the present invention is shown in FIG. In FIG. 2, a master station 1 is connected via a transmission path 3 to a plurality of slave stations 21 to 2n in the form of a bus. Note that in the figure, only the slave station 2I is shown for the purpose of simplifying the drawing. The slave station 2I sends the transmission signal from the master station 1 to the down line 3.
Receiver 21.1 receives via receiver 21.1. Automatic gain control circuit 22 that adjusts the output signal of the receiver 21 to a constant value. It is configured to include a driver 24° that sends its own station transmission signal to the main station 1 via the up line 32, an automatic amplitude control circuit 23 that variably adjusts the amplitude of the transmission signal from the slave station 21 to the up line 32, and the like.

A detailed configuration example of the automatic amplitude control circuit 23 is shown in FIG. As shown, a peak detector 231 detects the peak value of the output signal of the receiver 21. A variable amplifier 233 that amplifies the transmission data signal within its own station with a variable gain and supplies it to the driver 24. It is configured to include a control section 232 that adjusts the gain of the variable amplifier 233 according to the peak value detected by the peak detector 231, and the like.

The operation of this embodiment will be explained. A transmission signal with a constant amplitude is sent from the main station 1 to the down line 3], and this transmission signal has different transmission losses B1 to Bn on the down line 3I for each slave station 2] to 2n.
The signal is then received by the receiver 21 of each slave station 21 to 2n.

Now, to describe the operation of slave station 21, master station 1 and slave station 2
The transmission loss Bl of the down line 31 between I can be detected by detecting the output of the receiver 21 with the peak detector 231 of the automatic amplitude control circuit 23. That is, if the detected peak value is small, the transmission loss is large, and if the detected peak value is large, the transmission loss is small.

The peak value detected by the peak detector 231 is sent to the control unit 232, and the control unit 232 calculates the transmission loss 8. The variable amplifier 233 is controlled so as to have a gain of 1/2.

Here, assuming that the up line 32 and the down line 31 are installed under the same conditions, the transmission loss C1 of the up line 32 and the transmission loss B of the down line 31 are the same. For this reason, the variable amplifier 233 applies transmission signals of constant amplitude input to the automatic amplitude control circuit 23 to reduce the transmission loss of the down line 31 by 8. If the transmission signal is sent to the uplink 32 with a gain A of Slave station 21-2
The same applies to n. As a result, at the receiving end of the uplink 32 in the master station 1, each slave station 2. The received amplitudes (Ai-Bz) of the transmission signals from ~2n all have the same value.

Another embodiment of the invention is shown in FIG. This embodiment uses DIP to make the round trip delay constant for all slave stations by devising the wiring topology.
B (Delay Independent Pa5
The present invention is applied to a communication network using the siveBus system.

In this DIPB system, each slave station 21 to 2n is connected to the slave station 21, 2□-------2
They are connected in the order of n, and on the other hand.

On the uplink line 32, the slave stations 2n--22 and 21 are connected in the order of distance. The sum of the line length between main station 1 and slave station 2I on the down line 31 and the line length between slave stations 2 and 1 on the up line 32 is the sum of the line length between the slave stations 21 to 2n on the down line 31.
Therefore, the round trip delay of the signal sent from master station 1 is the same for all slave stations 2.
The same holds true for 1 to 2n.

In this FIG. 4 embodiment, the main station 1 and the slave stations 21 to
The basic configuration of 2n is the same as the embodiment in FIG. 2, and the automatic amplitude control circuit 23 of each slave station 21 to 2n also has the same configuration as in FIG. 3. However, the control method of the control section 232 in the automatic amplitude control circuit 23 is different from the above-described embodiment. That is, in this embodiment, the value (α
The control unit 232 performs control so that the variable amplifier 233 has a gain A corresponding to -Bi).

In other words, assuming that the up line 32 and the down line 31 are installed under the same conditions, the transmission loss of the up line 32 and the down line 3
The transmission loss of 1 is the same value. In the DTPB system, the sum of the line lengths of the down line 31 and up line 32 is equal for any of the slave stations 21 to 2n. In other words, slave station 2+ (i=1~n
), transmission loss Bt of down line 31, E up line 32
The sum of the transmission losses Ci (B+1C5) is a constant value α.

On the other hand, the slave station 21 at the receiving end of the uplink 32 in the master station 1
The received amplitude of the transmitted signal from the slave station 2I is the gain A of the automatic amplitude control circuit 23 of the slave station 2I minus the transmission loss Ci on the up line 32 (Ai-Ci).

Here, the gain A of the automatic amplitude control circuit 23 is a constant value α
The value obtained by subtracting the downlink transfer loss B from (Ai=α−B'i
), the reception amplitude at the main station receiving end is.

A, -ci = α-(B, +Ct). Here, since α is a constant value and B and +C are also constant values, the signal amplitudes of the transmission signals from each of the slave stations 21 to 2n end up being the same value at the receiving end of the uplink line 32 of the main station 1.

Yet another embodiment of the invention is shown in FIG.

In this embodiment, a peak detector 13 is provided in the main station 1 to detect the received amplitude of the signal input from each slave station 21 to 2n via the up line 32.
3, that is, the transmission losses B, ~Bn between the master station 1 and the slave station 2I on the up line 32 are converted into data, multiplexed by the multiplexer 14, and sent to the down line 31 via the driver 11. It is configured as follows.

On the other hand, each subordinate station 2. ~2n is equipped with a demultiplexer 25 that separates the multiplexed data with transmission losses B1 to Bn sent from the main station 1 via the down line 31, and this demultiplexer 25 demultiplexes the transmission loss B for the own station. The signal is separated and applied to the automatic amplitude control circuit 26.

As shown in FIG. 6, the automatic amplitude control circuit 26 is composed of a control section 261 and a variable amplifier 262, and is not equipped with a peak detector. To explain the operation of this embodiment in FIG.
4, and the driver 11 sends it to the slave station 21 via the down line 31.

In the slave station 21, this multiplexed data is sent to a demultiplexer 25.
Separate it and extract the local transmission loss B.

This is given to the automatic amplitude control circuit 26. In the automatic amplitude control circuit 26, a transmission loss B is inputted to a control section 261, and the control section 261 performs control so as to give a gain A corresponding to the loss Bi to the variable amplifier 262.

When all of the slave stations 21 to 2n perform such control, as a result, all the slave stations 2] to 2 at the receiving end of the uplink 32 of the master station 1
The received amplitudes of the transmitted signals from n match. Note that in this method, the down line 3I and the up line 32 do not need to be installed under the same conditions.

Yet another embodiment of the invention is shown in FIG. In this embodiment, each slave station 2. ~2n is equipped with a receiver 27 that receives the transmission signal on the uplink 32.

The receiver 27 is configured to receive a signal from an upstream slave station on the upstream line and input it to the automatic amplitude control circuit 23. The basic configuration of the Jizo amplitude control circuit 23 is as shown in FIG. 3, but the control by the control section 232 is different from the embodiment in FIG. Variable amplifier 233 so that the levels match
control.

That is, the slave station 2. of a transmission signal sent from another remote slave station (a slave station located upstream from the slave station 2I on the uplink 32, that is, a slave station located further away from the master station 1) via the uplink 32 to the master station 1. If the signal level reached is , then slave station 2
The automatic amplitude control circuit 23 of No. 1 adjusts the level A of the own station transmission signal so as to match this level Li. Slave 2I
If the transmission loss of the uplink line 32 between and main station 1 is CI, then
The reception amplitude of the transmission signal from the slave station 21 at the receiving end of the master station 1 is:

(A, -ci >), and on the other hand, the reception amplitude at the main station 1 of the transmission signal from the remote station is:

L i Ci-A! , Ci. Therefore, if each slave station receives the transmission signal from the slave station at the far end on the up line 32 and adjusts the signal level of its own transmission signal to match the signal level, each slave station will eventually receive the signal from the slave station at the far end. The level of the transmission signal of the own station is sequentially adjusted to the level of the transmission signal sent out from the slave station, and at the receiving end of the master station 1, the received amplitudes of the transmission signals from each slave station 21 to 2n all match. It turns out.

〔Effect of the invention〕

According to the present invention, burst-shaped transmission signals from slave stations having different transmission losses are automatically adjusted to substantially the same signal level at the receiving end of the master station.

Even when the transmission speed becomes high, it becomes possible to receive transmission signals from each slave station without error in the master station without using a high-speed automatic gain control circuit.

[Brief explanation of the drawing]

FIG. 1 is a principle block diagram according to the present invention. FIG. 2 is a block diagram showing a communication network that performs a transmission amplitude control method as an embodiment of the present invention. FIG. 3 is a detailed block diagram of the automatic amplitude control circuit in the embodiment of FIG. 2. FIG. 4 is a block diagram showing another embodiment of the present invention. FIG. 5 is a block diagram showing still another embodiment of the present invention. FIG. 6 is a detailed block diagram of the automatic amplitude control circuit in the embodiment of FIG. 5. FIG. 7 is a block diagram showing still another embodiment of the present invention. FIG. 8 is a block diagram showing a bus-type communication network. FIG. 9 is a block diagram showing a conventional bus-type communication network. FIG. 10 is a detailed block diagram of the automatic gain control circuit in FIG. 9. FIG. 11 is a diagram showing burst block signals transmitted and received through a bus-type communication network. In fig. 1-Main station 2. ~2n-Slave station 3-Transmission line 31-Down line 32-Up line 11, 2t---Driver 12.21-Receiver 14-Multiplexer 25-Demultiplexer 15.22-Automatic gain control circuit 23.26-Automatic amplitude control Circuit 152, 231.13 - Peak detector 232.261
--Control unit 15L233, 262-variable amplifier

Claims (1)

[Claims] 1. In a communication network in which a master station (51) and a plurality of slave stations (52_1 to 52n) are connected by a transmission line (53), detecting signal transmission loss in the transmission line (53). Each slave station (52_1 to 52n) has a transmission loss detection circuit (54) that has a transmission loss detection circuit (54), and a transmission circuit (55) of each slave station (52_1 to 52n) has a transmission level control circuit (56) that variably adjusts its own transmission level.
A transmission amplitude control system, wherein each slave station is configured to adjust the transmission level of its own transmission level control circuit (56) according to the transmission loss value detected by the transmission loss detection circuit (54). 2. The transmission loss detection circuit is provided in each slave station and is configured to detect the transmission loss of the transmission signal transmitted from the master station to each slave station, and the transmission circuit of each slave station is configured to detect the transmission loss of the transmission signal transmitted from the master station to each slave station. 2. The transmission amplitude control system according to claim 1, wherein the transmission amplitude control system is configured to give a gain corresponding to transmission loss to the local station transmission signal and send it to the main station. 3. The transmission loss detection circuit is provided in the master station and is configured to detect the transmission loss of the transmission signal from each slave station, and the transmission circuit of each slave station is notified of the transmission loss of its own transmission signal by the master station. 2. The transmission amplitude control system according to claim 1, wherein the transmission amplitude control system is configured to give a gain corresponding to the notified transmission loss to the local station transmission signal and send it to the main station. 4. The transmission loss detection circuit is provided in each slave station and is configured to detect the signal level of the transmission signal from the slave station located upstream from the own station on the upstream transmission path, and the transmission circuit of each slave station is configured to detect the signal level of the transmission signal from the slave station located upstream from the own station on the transmission path. 2. The transmission amplitude control system according to claim 1, wherein the transmission amplitude control system is configured to give a gain corresponding to the signal level detected by the local station transmission signal to the local station transmission signal and send it to the main station.