JPH02162849A - Data transmission system - Google Patents

Abstract

PURPOSE:To suppress the production of a transmission error by providing a gain adjustment means adjusting a reception gain to an optimum reception level through the reception of a test signal to a terminal spatial transmission unit. CONSTITUTION:A spatial transmission unit 1 for satellite sends a test signal to a spatial transmission unit 3 for terminal and the spatial transmission unit 3 for terminal receives the test signal and uses a reception level detection circuit 11 to detect an output of a reception amplifier 52. Then a signal processing circuit 13 obtains the optimum gain of the reception amplifier 52 and the output of the signal processing circuit 13 allows the gain adjustment circuit 12 to adjust the gain of the reception amplifier 52. Thus, the reception level is not fluctuated independently of the distance between both the spatial transmission units 1, 3 or the deviation of the direction of the spatial transmission unit for terminal, no transmission error is caused and the reliability of the data transmission is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a data transmission system used in a local area network or the like in which a large number of personal computers or the like are connected and data is transmitted between them.

[Prior art 1] Conventionally, a local area network (LAN) using a personal combinator as a work stage,
), data was transmitted by connecting each workstation with a wired transmission line. In other words, nearby workstations are connected by transmission lines using floor wiring or desk wiring, and ceiling wiring is used to connect workstations that are a little further away or between workstations on another floor. However, when wired transmission lines are used in this way, there are problems in that wiring work is time-consuming and aesthetically unsatisfactory.

Therefore, the inventors of the present invention used optical space transmission for the rising wiring or falling wiring between the floor or desk top and the ceiling, eliminating the standing wiring and falling wiring, saving the labor of wiring work, and We are proposing a data transmission system that does not spoil the aesthetics.

In this data transmission system, as shown in Fig. 12,
A workstation is equipped with a plurality of workstation groups each consisting of a plurality of workstations (2, l to 2,) connected to each other by a wired transmission line (for example, 11) and transmitting data to each other via the transmission line (11). Terminal space transmission unit for each 217 group) 31-3 zt33
. . are provided, and the above-mentioned terminal space transmission units 3□3□, 3.
(a plurality of satellite spatial transmission units corresponding one-to-one to each other) 1. ．． 12.1. ... is installed on the ceiling, and the corresponding spatial transmission unit (for example, L-3+) performs half-duplex data transmission using optical pulse signals in the dark, and the data transmission between the workstations is carried out via the wired cable on the ceiling side. Transmission line! All work stages Harun 211~2131221~22)? 231-2
1. ... so that data can be transmitted between them.

By the way, in the above-mentioned data transmission system, there is a problem in that when an obstacle X exists between the terminal space transmission unit 3 and the satellite space transmission unit 1, optical space transmission cannot be performed. Therefore, as shown in the diagram on page 113, two lines are connected to the same transmission line L+j'zt...
Space transmission unit for terminals 3119312.3
2113221..., for example, one terminal space transmission unit 312 connected to the transmission line 11.
There is also a device in which the other terminal space transmission unit 3□ can normally perform space transmission even if the space transmission unit 3□ is blocked from light as shown in the figure.

[Problem to be solved by the invention] However, the space transmission unit for the terminal provided at cost) 3++3□, 3. ... or a satellite spatial transmission unit installed on the ceiling side) 1. When optical space transmission is performed using 12, 1, etc., and the distance between each space transmission unit 1°3 is short, the output of each receiving amplifier is large, and sometimes the output is saturated, resulting in the final The reproducibility of waveforms may deteriorate.

Conversely, if the distance between spatial transmission units 1 and 3 is short,
The ceiling receiving amplifier output is small, and as in the case described above, the reproducibility of the final waveform may be poor.

Furthermore, there is a possibility that the optical axes of the terminal spatial transmission unit 3 and the satellite spatial transmission unit 1 will be misaligned due to vibrations, human contact, etc., resulting in a decrease in the amount of light received. In other words, they cause transmission errors. However, at this time, no countermeasures had been taken against the problem fish mentioned above.

The present invention has been made in view of the above points, and an object thereof is to provide a data transmission system in which transmission errors are less likely to occur.

1 Measures to Solve the Problem g'i1 In order to achieve the above object, the specified invention includes a test signal transmitting means for transmitting a test signal toward a terminal spatial transmission unit when a transmission signal is not transmitted, and a satellite spatial transmission unit. In addition, the terminal space transmission unit is provided with a dein adjustment means for receiving the test signal and adjusting the reception gain to an optimum reception level for transmitting and receiving the transmission signal. In addition, a test signal requesting means for transmitting a test signal request signal toward the satellite spatial transmission unit is provided in the terminal spatial transmission unit, and when adjusting the reception gain, the test signal is sent from the terminal spatial transmission unit to the satellite spatial transmission unit. The test signal request signal may be sent at any time or periodically.

Also, 1511:i! ! In order to achieve the above object, the present invention includes a test signal transmitting means for transmitting a test signal toward a spatial transmission unit for a terminal on the other side, and a means for receiving the test signal and receiving the test signal at an optimal reception level for transmitting and receiving the transmission signal. A gain adjustment means for adjusting the gain by 14 nodes is provided in each terminal space transmission unit. In this case, the test signal may be transmitted at any time or periodically.

(Function) In the specified invention, configured as described above, the test signal is transmitted by the satellite space transmission unit, and the receiving gain is adjusted by the terminal space transmission unit that receives this test signal, thereby transmitting both air and air signals. This is to prevent the reception level from fluctuating due to the distance between the dark transmission units or the direction shift of the terminal spatial transmission unit.

In addition, in the related invention, the test signal is transmitted by the terminal space transmission unit, and the reception gain is set to WI4 by the terminal space transmission unit that receives the test signal.
ffli prevents the reception level from varying due to the distance between the same space transmission units or the direction shift of the terminal space transmission unit.

[Example 11 Figure 1 shows an example of the specified invention. The basic configuration of the data transmission system to which this specified invention is applied is the same as that shown in Figure 13. A plurality of satellite spatial transmission units 11, 1□tl'l... each connected by line l, and each transmission line 1Ift.
Work stage jars 2□~2 +31L consisting of multiple personal computers connected to '21...
l~2□3,2,~21. . . . and a plurality of terminal space transmission units 3, which are provided for each group of 5 work stages and are provided with transmission and reception directions corresponding to the satellite space transmission units 1 □ 12, 13 . . .
*31□, 3□+8322.33+132...

The satellite space transmission unit 1 of this embodiment includes an optical transmission circuit 4 including a light emitting element 41 and a transmission driver 42,
The optical receiving circuit 5 includes a light receiving element 51, a receiving amplifier 52, and a logic conversion circuit 53, a line receiver 6, and a line driver buffer. The optical transmission circuit 4 converts the transmission signal into an optical pulse signal and transmits it, and the optical reception circuit 5 receives the optical pulse signal from the terminal space transmission unit 3 and demodulates it into a transmission signal. It is sent out to the transmission line r via the line driver buffer. Note that the logic conversion circuit 53 shapes the waveform of the output of the receiver 7 amplifier 52.

In addition, in this satellite space transmission unit 1, a transmission date 9 is provided between the optical transmission circuit 4 and the line receiver 6, and a reception date 10 is provided between the optical reception circuit 5 and the line driver buffer. The transmission/reception date control circuit 8 controls the opening/closing of the transmission date 9 and the reception date 10 so that the transmission signal and the reception signal do not collide on I. In addition, space transmission unit 3 for terminal
also have the same configuration. Therefore, it is possible to perform half-duplex data transmission between the corresponding spatial transmission units (for example, the terminal spatial transmission unit 3 and the satellite spatial transmission unit 11) using optical pulse signals. The circuit configuration described above is a basic configuration that is also included in the conventional example.

The basic data transmission between the work stages 211-2°, . . . will be briefly explained below. Here, a case will be described in which data is transmitted from workstation 2□. Work stage 1 21. The transmission signal of (C) is sent to the terminal space transmission units 3Il and 3I2 via the transmission line 11, converted into an optical pulse signal, and sent to the corresponding satellite space transmission unit 11 on the ceiling side, and the transmission line! , to Worksty Silan 2121213.

The spatial transmission unit 1 that receives the optical pulse signal demodulates the transmission signal and sends it out to the transmission line 2. Another satellite space transmission unit 1□, 1. which captures the transmission signal sent through this transmission line e. operates in the same manner as the terminal space transmission unit 3, and converts the transmission signal into an optical pulse signal again, and the terminal space transmission unit 3□.

Send to 32□133+*L2. The terminal space transmission unit 32+ receives this optical pulse signal.
13 x2s 3! 11332 operates in the same way as the satellite space transmission unit 1□, and sends the transmission signal to each work stage 5 to 2 through each transmission line 12rls.
231231-2) Send to 31. In other words, workstation 23. The transmission data sent by is transmitted to all workstations 2゜...

Note that even if a wired transmission system and an optical space transmission system coexist as in this data transmission system, data transmission is performed normally because transmission and reception are performed at half duplex.

By the way, the emitted light power from the spatial transmission unit 1.3 having such a configuration is constant, and the received light power varies depending on the directionality of the terminal spatial transmission unit 3 and the distance between the spatial transmission units 1 and 3. As explained in the technical section, it causes transmission errors. Therefore, it is necessary to perform transmission while maintaining optimal reception conditions. Therefore, in this embodiment, the gain of the receiving amplifier 52 is set to an optimal state. Note that the data transmission system to which this embodiment is applied is 1.
Since two terminal spatial transmission units 3 are provided for one satellite spatial transmission unit 1, it is inconvenient to change the gain of the receiving amplifier of the satellite spatial transmission unit 1.

Therefore, the input of the receiving amplifier of the terminal space transmission unit 3 is adjusted.

Specifically, as shown in FIG. 1, there is a reception level detection circuit 11 that detects the reception level from the output of the reception amplifier 52, a dein adjustment circuit 12 that adjusts the gain of the reception amplifier 52 to g4S, and a reception level detection circuit 12 that detects the reception level from the output of the reception amplifier 52. A signal processing circuit 13 composed of a microcomputer is provided, which determines the gain of the receiving amplifier 52 which is adjusted by the gain adjustment circuit 12 from the output of the circuit 11.

The operation of the circuit that adjusts the above reception gain is shown at 70- in Fig. 3.
Explain according to the chart. This reception gain adjustment is
Figure 2 (b) is different from the original transmission signal shown in Figure 2 (&).
) is used when the above transmission signal is not being transmitted. Note that the test signal has a wider pulse width than the actual transmission signal so that it can be easily distinguished and level detection can be easily performed.

When the power is turned on, the signal processing circuit 13 made up of a microcomputer is initialized and executes the written blog program from the beginning. First, the signal processing circuit 13 turns off the transmission date 9 and the reception date 10, and maintains this state so that no transmission signal is transmitted or received.

Next, determine whether it is for the satellite or for the terminal. This setting for satellite use and terminal use is performed by setting switch SW1.

In the case of the satellite spatial transmission unit 1, a test signal is transmitted toward the terminal spatial transmission unit 3, and the terminal spatial transmission unit 3 adjusts the optimum gain based on the test signal and sends back a confirmation signal. Wait until it clears up.

Then, if the confirmation signal is received, the transmission/reception date is 9°10.
The state in which the OFF state is held is released and the state is entered into a state where normal transmission signals can be transmitted and received.

On the other hand, in the case of the terminal space transmission unit 3, it waits until the test signal from the satellite space transmission unit 1 is transmitted, and when the test signal is received, the output of the receiver 7 amplifier 52 is set to the reception level. Detected by the detection circuit 11, the optimal gain of the receiving amplifier 52 is determined by the signal processing circuit 13 according to the level, and the gain adjustment circuit 12 performs gain 1I11 of the receiving amplifier 52 based on the output of the signal processing circuit 13. After that, a confirmation signal indicating that the adjustment of the reception data has been completed is sent to the satellite spatial transmission unit 1, and the transmission/reception data (9.10) is released from the off state, allowing normal transmission and reception of transmission signals. enter the state.

[Embodiment 2] Fig. 4 shows another embodiment of the specific invention. In this embodiment, a gain adjustment switch SW2 is provided, and when this switch SW2 is operated, the terminal space transmission unit 3 changes to the satellite space transmission unit. The test signal request signal is sent to the terminal space transmission unit 1, and the test signal sent from the satellite space transmission unit 1 causes the terminal space transmission unit 3 to adjust the reception gain. It is recommended that you do this.

A method of adjusting the reception gain will be explained according to the fifth @7a-chart. This reception gain adjustment is also performed using the same test signal as in the first embodiment described above. When the power is turned on, the signal processing circuit 13 composed of a microcomputer starts executing the program. In this embodiment, the signal processing circuit 13 first determines whether it is for the satellite or for the terminal. to judge. Note that the settings for the satellite and for the terminal are performed by setting the switch SWI, as in the tJIJl embodiment.

In the case of the satellite space transmission unit 1, it waits for a test signal request signal to be sent from the terminal space transmission unit 3, and if this test signal request signal is sent, the transmission/reception data) 9 .10 is turned off, this off state is maintained, and a test signal is transmitted toward the terminal space transmission unit 3.

After that, the terminal spatial transmission unit 3 adjusts the optimum gain using the test signal, and waits for the confirmation signal to be sent back indicating that the optimum gain adjustment has been completed, and then receives the confirmation signal. Then, the transmission/reception data is released) 9.10, the state in which the off state is maintained is released, and the state is entered into a state in which normal transmission signals can be transmitted and received.

On the other hand, in the case of the terminal space transmission unit 3, wait until the gain adjustment switch SW2, which is operated to adjust the reception gain, is turned on;
When W2 is turned on, transmit/receive data) 9.10 is turned off (transmission signal is not being transmitted), then transmit/receive data) 9.10 is kept off and the satellite space is A test signal request signal is transmitted to the transmission unit 1. After that, the satellite spatial transmission unit 1 transmits a test signal and waits for it to arrive. When the test signal is transmitted, the output of the receiving amplifier 52 is detected by the receiving level detection circuit 11, and the level The signal processing circuit 13 determines the optimal gain of the receiving 7 amplifier 52 according to the signal processing circuit 13, and the 2-in adjustment circuit 12 adjusts the gain of the receiving 7 amplifier 52 based on the output of the signal processing circuit 13. After that, a confirmation signal indicating that the adjustment of the reception gain has been completed is transmitted to the satellite spatial transmission unit 1, and the state in which the transmission/reception date 9.10 is held in the off state is released, allowing normal transmission and reception of transmission signals. to go into.

[Example 31 FIG. 6 shows still another embodiment of the specific invention.

The configurations of the spatial transmission units 1 and 3 of this embodiment are the same as those of the first embodiment, and the terminal spatial transmission unit 3 is configured to transmit a test signal request signal to perform reception gain control at regular intervals. This is what I did.

FIG. 6 shows the reception gain adjustment method of this embodiment. In this embodiment, when the power is turned on, the signal processing circuit 13 first determines whether it is for the satellite or the terminal, as in the tlIJ2 embodiment. In the case of satellite sky/dark transmission unit 1,
It operates similarly to the second embodiment. On the other hand, in the case of the terminal space transmission unit 3, a built-in timer in the signal processing circuit 13 that measures a certain period of time is started, and when the timer times out, it is determined whether both the transmitting and receiving data (9.10) are turned off. Please confirm this sending/receiving date)
9. After maintaining the OFF state of 10, a test signal request signal is transmitted to the satellite space transmission unit 1. Thereafter, the reception dean is optimally adjusted in the same manner as in the second embodiment, and a state in which the transmission signal can be transmitted and received is entered. In the case of this embodiment, the timer is restarted from this time, and the above-described operation is repeated.

[Embodiment 4] In the first to third embodiments described above, the satellite sky/dark transmission unit 1 with a wide directivity angle was provided on the ceiling side, but in this embodiment, which is an embodiment of the related invention, Terminal space transmission units 3 with narrow directivity angles are provided on both the side and end chains, and each terminal space transmission unit 3 is made to correspond to each other in one piece, similar to the configuration shown in FIG. 12 of the conventional example. This is applied to a data transmission system that performs transmission. As shown in FIG. 7, the terminal space transmission unit 3 is the same as the first embodiment except that the switch SWI is omitted.

In this embodiment, when the power is turned on, the signal processing circuit 13 is initialized as shown in FIG. 8, and the written program is executed from the beginning. First, the signal processing circuit 13 closes the transmission/reception dates 9 and 10 and maintains this state so that no transmission signal is transmitted or received.

Next, a random waiting time is set using a random number or the like so that it does not operate simultaneously with the spatial transmission unit 3 for the other party's terminal, and the signal processing circuit 13 to which the waiting time has been set is set.
Starts the built-in timer. If the test signal is not received from the terminal space transmission unit 3 of the other party by the time the timer expires, the test signal is transmitted to the other party. After that, wait for a test signal to be sent from the other side, and when the test signal is received, adjust the optimal gain, release the transmit/receive data (9.10) from the off state, and perform normal operation. enters a state in which it is possible to send and receive transmission signals.

On the other hand, if a test signal is received from the other party before the timer times up, the timer is reset, the reception gain is adjusted, and the test signal is transmitted to the other party. Then, release the closed state of 9.10,
Enters a state in which normal transmission signals can be sent and received. In this way, even if the terminal space transmission units 3 with narrow beam angles are used on the ceiling side and the end chain, transmission errors will be less likely to occur, and since all the space transmission units will have the same configuration, the system price will also be reduced. be able to.

[Example 5] This example shows another example of the related invention.
As shown in the figure, a gain adjustment switch SW2 is provided so that the reception gain can be adjusted at any time.

In this embodiment, as shown in FIG. 10, it is first determined whether the gain adjustment switch SW2 is turned on or not.
If the switch SW2 is not turned on, it is repeatedly determined whether a test signal is sent from the other party. Then, when the test signal is received, the transmission/reception date 9.10 is held in the off state, the reception gain is adjusted, and then the test signal is transmitted to the other party.

After that, the transmit/receive data) 9.10 is released from the off state and returns to the monitoring state of the gain 111IrB switch SW2.

If the gain adjustment switch SW2 is turned on at some point, check whether the transmission of the transmission signal is interrupted, and then keep the transmit/receive data (9.10) in the off state and send the test signal to the other party. Send. After that, wait for a test signal to be sent from the other party, and when the test signal is received, the reception gain is adjusted and then the transmission/reception data is sent.9.
In this embodiment, when either gain adjustment switch SW2 is turned on, the reception gain is adjusted by both switches. I can like it.

[Example 61 FIG. 11 shows still another embodiment of the related invention.

The configuration of the terminal space transmission unit 3 is the same as that of the fourth embodiment.

In this embodiment, as shown in FIG. 11, a check cycle for gain adjustment is first set based on the number of holes, etc., and a timer is started accordingly. If a test signal from the other party is received before this timer times up, the reception gain is adjusted, and then the timer waits for the timer to time up. In this embodiment, When the timer times up, it sends a test signal. In other words, in this embodiment, the reception gain can be adjusted at regular intervals.

[Effects of the Invention] As described above, the present invention provides a test signal transmitting means for transmitting a test signal toward the terminal spatial transmission unit when the transmission signal is not transmitted, and the satellite spatial transmission unit is provided with a test signal transmitting means for transmitting the test signal to the terminal spatial transmission unit. The terminal space transmission unit is equipped with a gain adjustment means for adjusting the reception gain to the optimal reception level for transmitting and receiving transmission signals. The transmission unit can adjust the reception gain to the one that optimizes signal transmission.
Therefore, due to the distance between the same space transmission unit or the direction of the terminal space transmission unit,
There is an advantage that the reception level does not fluctuate, so no transmission errors occur, and the reliability of data transmission is improved. Note that the same effect can be expected when the same space transmission unit on the ceiling side and the cost price is a space transmission unit for a terminal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the circuit configuration of a space transmission unit according to an embodiment of the specified invention, FIGS. 2(a) and (b) are signal waveform diagrams showing the same transmission signal and test signal, and FIG. 70-chart showing the same operation as above, FIG. 4 is a block diagram showing the circuit configuration of the spatial transmission unit of another embodiment of the specified invention, tI%5 is a flow chart showing the same operation as above, and FIG. 6 is the specified invention 70- illustrating the operation of still another embodiment of
7 is a block diagram showing the circuit configuration of a space transmission unit according to an embodiment of the related invention, FIG. 8 is a 70-chart showing the operation of the same as above, and FIG. 9 is a space diagram of another embodiment of the related invention. Block diagram showing the circuit configuration of the transmission unit, 1st
Fig. 0 is a 70-chart showing the operation of the same as above, Fig. 11 is a 70-chart showing the operation of still another embodiment of the related invention, Fig. 12 is a configuration diagram of a local area network, and Fig. 13 is a diagram of another local area network. FIG. 2 is a configuration diagram of an area network. 1, ~1. is the space transmission unit for satellite, 2~2°, 2□, ~2! 3j 2:lI~233 is a workstation, 31,3□13313 +1t3 tie
3□193211331133□ is a terminal space transmission unit, 4 is an optical transmitting circuit, 5 is an optical receiving circuit, 11 is a reception level detection circuit, 12 is a gain adjustment circuit, 13 is a signal processing circuit, sw, , sw are switches, Llll12
113 is a transmission line. Agent Patent Attorney Ishi 1) Chief 7 Figure 3 Figure 10 Figure 11

Claims (6)

[Claims] (1) A plurality of workstation groups are connected to each other by a wired transmission line and transmit data to each other via the transmission line, and each workstation group is provided with a terminal space transmission unit with a narrow beam direction. A plurality of satellite spatial transmission units each connected by a transmission line with a wide directivity angle are installed on the ceiling in correspondence with the terminal spatial transmission unit, and half-duplex transmission is achieved using optical pulse signals between the corresponding spatial transmission units. A test in which a test signal is sent to the terminal space transmission unit when the transmission signal is not being transmitted, in a data transmission system in which data is transmitted between workstations via a wired transmission line on the ceiling side. A data transmission system in which a signal transmission unit is provided in a satellite spatial transmission unit, and a terminal spatial transmission unit is provided with a gain adjustment unit that receives the test signal and adjusts the reception gain to an optimal reception level for transmitting and receiving the transmission signal. . (2) The data transmission system according to claim 1, wherein the terminal space transmission unit is provided with test signal request means for transmitting a test signal request signal to the satellite space transmission unit when the transmission signal is not being transmitted. (3) The data transmission system according to claim 1, wherein the terminal space transmission unit is provided with test signal request means for transmitting a test signal request signal to the satellite space transmission unit at regular intervals. (4) A plurality of workstation groups are connected to each other by wired transmission lines and transmit data to each other via these transmission lines, and a terminal space transmission unit is provided for each workstation group. A plurality of spatial transmission units for terminals connected to each other are installed on the ceiling in correspondence with the spatial transmission unit for terminals on the floor side, and data is transmitted in half duplex using optical pulse signals between the corresponding spatial transmission units. In a data transmission system in which data is transmitted between a group of workstations via a wired transmission line on the ceiling side, a test signal transmitting means for transmitting a test signal toward a spatial transmission unit for a terminal on the other side, A data transmission system in which each terminal space transmission unit is provided with gain adjustment means for receiving a signal and adjusting the reception gain to the optimal reception level for transmitting and receiving the transmission signal. (5) The data transmission system according to claim 4, wherein each terminal space transmission unit is provided with test signal transmission means for transmitting a test signal at any time when the transmission signal is not being transmitted. (6) The data transmission system according to claim 4, wherein each terminal space transmission unit is provided with test signal transmission means for periodically transmitting a test signal when no transmission signal is being transmitted.