JPH06188837A - Optical radio data transmission system - Google Patents

Abstract

PURPOSE:To attain an optical radio data transmission between two different communication areas. CONSTITUTION:This system is equipped with a first modem equipped with a light emitting part 5 for outputting a transmission signal, light receiving part 11 which receives an output light from the other modem, and photoelectric- converts it, demodulator 13 and decoder 2 which demoudates and decodes a received signal, data processor 4 which transmits the decoded data through a connector 7 to a terminal equipment when the address of the decoded data is its own device, or operates a prescribed signal processing to the data from the terminal equipment, and supplies the data through an encoder 14 and a modulator 6 to the light emitting part 5, and bidirectional driver 8 which switches an input and output direction by a control signal from the data processor 4, and a second modem MO equipped with a frequency converter 3 which operates a repeating operation by converting the carrier frequency of the received signal from a light receiving part 11, supplying it to a light emitting part 5, and allowing the light emitting part 5 to output a light, in addition to the constitution of the 1 MK. The system is equipped with at least one pair of the two second MODEM connected through a cable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical wireless data transmission system for transmitting wireless data using light such as infrared rays as a carrier, and in particular, a service is provided by providing a modem with a relay function or a data transmission function. Area (communicable range)
The present invention relates to an optical wireless data transmission system that realizes the expansion of the.

[0002]

2. Description of the Related Art Recently, in Japan, OA (Office Automatio
n), the number of office automation devices such as personal computers (PCs) and word processors (Word Processors) installed in offices is increased, and work is performed, and personal computer communication is performed via a modem or communication line. It is now widely practiced to install a large-scale computer device, which is a higher-level device, in one room and to transmit data via a communication control device, a modem, and a communication line, which are terminals of the device. Wired cables are generally used for such data transmission, but wireless communication using light such as infrared rays has been recently developed.

As is well known, personal computers, word processors, etc. are composed of a device main body and terminals such as a keyboard, a display device, and a printer, and the main body and the terminals are generally specified by Centronics (hereinafter referred to as "Centro specification"). Abbreviated) and the like. Out of the terminal
Since the printer is used relatively infrequently, one printer is often used for a plurality of personal computers, word processors, and other device bodies.

In this case, a plurality of device bodies are connected to a selection device for switching these inputs with a cable, and the selection device and the printer are connected with a cable.
If there is no such selection device, there is the inconvenience of having to remove and insert the cable terminal each time the device body using the printer is replaced. In addition, even if there is a selection device or a printer that does not serve as a printer, a cable between the main body and the terminal device is indispensable, which hinders the appearance and spoils the aesthetics of the office. Further, it is troublesome because the cables and the like have to be reconnected each time the layout in the office is changed, and since the cable length is finite, the installation location is limited and it is easy to make effective use of space. There were drawbacks such as.

As an OA device capable of solving these drawbacks, a system has recently been developed which transmits and receives signals between the main body, terminals and between terminals by using near infrared rays having a wavelength of around 900 nm instead of cables. Has been started to be used. A conventional example of such a data transmission system will be described with reference to the drawings. FIG. 2 is a plan configuration diagram showing a basic system of a conventional optical wireless data transmission system. Two data rooms (each communication area in this case) 21 and 22 partitioned by a wall W are provided with the data transmission system, respectively. It indicates that they are installed one by one.

In FIG. 2, MK _{1 to} MK ₆ are modems (modulators / demodulators), and PC _{1 to} PC ₄ are personal computers (or word processors) which are terminals connected to the modems by cables (printers are not generally included). Yes, PR _{1 and} PR ₂ are printers. Below, this printer PR _1, PR ₂ and personal computer PC _{1 to} PC ₄
Will be generically referred to as a "terminal" for convenience. In addition,
The modem MK _3, MK ₆ which is connected to the printer PR _1, PR _2, sometimes have a function as such for later relay device, in which case the "master unit" and (respectively MO _1, MO ₂₎ I will call it and distinguish a modem without relay function as a slave unit (MK).

[0007] The arrows in FIG. 2 shows that the two-way data communication between between each modem MK _1, MK ₃ and MK _5, MK ₆ is taking place (which is an optical link). Since the two rooms 21 and 22 in which the respective optical communications are performed are partitioned by the wall W as described above, the communication areas are completely independent, and therefore the light having the same carrier frequency is used in both rooms. However, there is no mutual interference or collision.

[0008]

In the above-mentioned conventional optical wireless data transmission system, although the transmission speed is high, it is vulnerable to an obstacle in the middle of the transmission path, and especially if it is partitioned by the wall W as described above, optical communication is possible. However, there is a drawback that optical communication cannot be performed even in such a range (distance that light can reach sufficiently).

[0009]

As a plurality of modems used in the optical wireless data transmission system of the present invention, a light receiving section for receiving output light from another modem and converting it into an electric signal,
A demodulator and a decoder that demodulate and decode this electric signal respectively, and if the data decoded by this decoder is decoded and it is determined that it is addressed to itself, it is sent to the terminal device via the connector or from the terminal device. A data processor that performs a predetermined signal processing on the data of, a coder and a modulator that respectively encode and modulate the output of the data processor, and a light emitting unit that converts the transmission signal from the modulator into light and outputs the light.
The first modem is provided with a bidirectional driver which is connected between the data processor and the connector and whose input / output direction can be switched by a control signal from the data processor.

In addition to the configuration of the modem, a frequency converter for performing a relay operation by changing the carrier frequency of the signal received and photoelectrically converted by the light receiving unit and then supplying the light to the light emitting unit for optical output is further provided. The above problem is solved by providing at least one set in the system having a second modem provided and two second modems being connected to each other via their connectors.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical wireless data transmission system of the present invention will be described with reference to the drawings. FIG. 3 is a basic system configuration diagram of an optical wireless data transmission system 1a according to the first embodiment of the present invention. As is clear from comparing FIG. 3 with FIG. 2, modems MO _{3 and} MO ₄ (having a function as a master unit) are installed in the two rooms 21 and 22 across the wall W, respectively.
The difference between the two modems MO _{3 and} MO ₄ is that they are connected by a single cable C (for example, Centro type), and other configurations are the same as in FIG.

Next, specific configurations of the two types of modems MK and MO, which are the main parts of the system of the present invention, will be described with reference to FIG. FIG. 1 (A) is a block diagram of a modem MK having a function as a slave unit, 11 is a light receiving unit, 2 is a decoder (decoder), 4 is a data processor, 5 is a light emitting unit, 6 is a modulator, 7 is a connector (for example, Centro type) for connecting to a terminal device, 8 is a bidirectional (I / O) driver,
9 is a carrier detection circuit, 13 is a demodulator, 14
Is an encoder. The connector 7 and the bidirectional driver 8 may be collectively referred to as an interface.

FIG. 1B is a block diagram of a modem MO having a function as a master unit. In addition to the configuration of the slave unit modem MK described above, a frequency converter 3 and an amplifier 12 are further provided. . Therefore, the carrier frequency f ′ of the signal light output from the master unit is the carrier frequency f of the output signal light from the slave unit.
Unlike (for example, 2.5 MHz), when a square circuit is used as the frequency converter 3, f '= 2f. The directivity of the light receiving section 11 and the light emitting section 5 of the modem MO is preferably wider than that of the modem MK.

When the Centro type connector 7 is used as the connector 7, the detailed circuit configuration of the connector 7 and the bidirectional driver 8 is as shown in FIG. FIG. 4 is a circuit block diagram corresponding to the slave modem MK, but illustration of some components such as the carrier detection circuit 9 is omitted. In addition, the same components as those in FIG. is doing. In FIG. 4, among the input / output lines from the connector 7,
STROBE, BUSY, and ACKNLG are three control lines.
The bar drawn on the characters STROBE, ACKNLG and INIT, ERROR means that it operates in negative logic as is well known, but in this specification, it is expressed by adding-(-) immediately before the character. To do.

Next, referring also to FIGS. 1, 3 and 4,
Regarding the specific operation of the modem, for example, the personal computer in FIG.
An operation example of printing (hard copy) the text created by the PC ₁ by the printer PR ₁ or PR ₂ will be described. When the power is turned on, it is assumed that the bidirectional driver 8 is all set to the input side when viewed from the data processor 4 (the signal is input to the data processor 4 side) by the control lines CL _{1 and} CL ₂ . Therefore, the signal data from the terminal device (for example, the personal computer PC ₁ ) cable-connected to the modem is ready to be received at any time.

In the modem MK ₁ used as a slave unit, digital data from a terminal device (personal computer PC ₁ ) cable-connected to this is input to the data processor 4 via the connector 7 and the bidirectional driver 8. , Here, a predetermined number (for example, 256 bytes) of data are collectively converted into a data packet format that conforms to the data format of the optical communication protocol, and the ID (index) No. of the other party to be linked can be converted as necessary. Included, encoder 14
Is encoded and supplied to the modulator 6. The encoder 14 can be incorporated in the data processor 4.

The modulator 6 modulates the signal data with a carrier of frequency f (for example, FM, PM, etc.) and supplies it to the light emitting section 5, where it is converted into signal light of carrier frequency f and emitted. In that case, the carrier detection circuit 9
The data processor 4 has not communicated with other devices based on the information from (that is, "there is no carrier").
It goes without saying that light emission is output when it is determined.

The signal light output in this manner is caught by the light receiving section 11 on the modem MK ₃ side, photoelectrically converted there, and then demodulated and decoded by a demodulator 13 and a decoder (decoder) 2, respectively. It is decoded) and supplied to the data processor 4. The data processor 4 analyzes the data, checks the ID No. contained in this data, and if it is the same as your own ID No., determines that it is addressed to you, extracts only the information data part, and the bidirectional driver 8 , Is sent to the printer PR ₁ which is a terminal device via the connector 7 to perform printing. At that time, if necessary, a response packet is created by the data processor 4, and the encoder 14 and modulator 6
Then, the signal processing is performed and the light emitting section 5 emits light toward the modem MK ₁ . The decoder 2 can also be incorporated in the data processor 4.

In this way, the data processor 4
Also forms a communication command response of the optical communication protocol with a similar data packet, and also performs communication control according to this optical communication protocol. For example, printer PR ₁
Is working, sends a command response "BUSY" to the modem MK ₁ . Then, the modem MK ₁ side waits for a certain period of time, then again issues a link setting request message (-STROBE) to the modem MK ₃ , and thereafter repeats this operation until link setting is realized.

When there are a plurality of printers in the same communication area 21 as in the third embodiment shown in FIG. 7, which will be described later, when there is a command response "BUSY" from the modem MK ₃ , or When there is no command response within a fixed time, it is convenient to configure the data processor 4 (in terms of software) so that the link destination is changed to the modem MK ₇ and light emission is output.

Alternatively, it is easy to configure the data processor 4 so as to emit light without specifying a link partner from the beginning and to set a link with the partner who first returns a command response "-ACKNLG". In the configuration of the first embodiment, only one printer PR ₁ is installed in the room 21, but there is one printer PR ₂ in the adjacent room 22,
Since the printer PR ₂ can be linked to the printer PR ₂ via the modems MO _{3 and} MO ₄ and the cable C, its specific operation will be described below with reference to the flowchart of FIG.

First, each of the modems MO _{3 and} MO ₄ has a function as a master unit, and thus has the block configuration shown in FIG. 1 (B). When the interface is Centro type, when the power is turned on, the control line in FIG.
It is assumed that the bidirectional drivers 8 are all set to the input side (the leftward arrow side in FIG. 4) when viewed from the data processor 4 by the control signals from CL _{1 and} CL ₂ (step in FIG. 5). The data processor 4 of the modem MK ₃ has a light receiving unit 11
Optical packet reception and -ST from modem MO ₄
It constantly monitors the ROBE input and also serves to switch the modem to transmitter or receiver depending on which one becomes active first.

That is, when the modem MO ₃ first receives an optical data packet (step), the data processor 4
Supplies a control signal to the bidirectional driver 8 via the control lines CL _{1 and} CL ₂ , and the pins ~ and (31) of the connector 7 are output to the output side by the control signal from the control line CL ₁ and the control line CL ₂ Similarly, the pins (10) to (13) and (32) are switched to the input side by the control signal from (, respectively, that is, the interface is switched to the receiving side so that the modem MO ₃ can act as a receiver (step
)}, And outputs the data to the modem MO ₄ side via the cable C at the interface control timing. The numbers after this are not enclosed in circles, so they are substituted with () (the same applies below).

Modem supplied with data from modem MO ₃
Since the MO ₄ inputs (step) the -STROBE signal prior to the reception of the optical data packet by the light receiving unit 11, the connector 7 is connected by the control line CL ₁ in the modem MO ₄ .
, Pins (10) to (13) and (32) are connected to the input side by the control line CL ₂ (ie, the interface so that the modem MO ₄ acts as a transmitter). To the transmitting side (step)}, data is input at the rising (or falling) timing of the control signal, and the data processor 4 packetizes the data. After that, the signal is output to the modulator 6, modulated (encoded) here, further converted to a frequency f ′ (for example, 5. MHz) by the frequency converter 3, and emitted from the light emitting unit 5 in real time as an optical signal and output. .

When the modem MK ₆ receives the signal light output from the modem MO ₄ in this way, the modem MK ₆ checks the operation status of the printer PR ₂ connected to itself and stops the operation (standby). ), The response signal of −ACKNLG is transmitted to the modem MK ₄ by light emission. This establishes a link connection, and printer PR ₂ has four modems MK _1, MO _3, MO _4, and MK.
Print the data sent from PC ₁ via PC ₆ . In this way, the modem MK _1,
Cable M and repeater modem MO _3, MO between MK ₆
It is now possible to communicate via ₄ .

Here, a specific method for setting a communication partner will be described in detail. As an example, “SYN + SYN + STX +
STX + control code + communication partner + ETB + ETB +… + ETB + ETB + FF + FF
+ ETX + ETX ”is used as a command (control data), which is a pattern that is rarely seen in normal data. The data processor of the sending modem that receives such a command from the bidirectional driver 8 has a control code other than 0. If so, the command with the control code changed to 0 and the following data are transmitted to address 0. If the control code is 0, the command is discarded, and the following data is transmitted to the communication partner of the command. The receiving side of address 0 which has received the command and the data by the signal light outputs the command and the data as they are according to the control signal timing of the interface.

As a more specific example, the above personal computer PC
_The case where the signal light is output by designating ₁ to the printer PR ₂ (ID number of the modem MK ₆ is 6) will be described. When a command (control code ≠ 0, communication partner ID No. = 6) and print data are output from the personal computer PC ₁ , this is sent from the modem MK ₁ to the modem MO _{3 in the} same room 21.
The modem MO _{3 which} receives this switches to the receiving modem according to the above-mentioned operation principle, and outputs a command (control code = 0, communication partner = 6) and print data via the interface. The modem MO _{4 in} the room 22 that receives the request switches to the transmitting modem according to the above-mentioned operation principle, and sends the print data to the command communication partner (in this case, the modem MK ₆ ). The modem MK _{6 which} receives this outputs the print data to the printer PR ₂ connected to it and prints it.

Next, a second embodiment of the system of the present invention will be described with reference to FIG. FIG. 6 is a system configuration diagram of an optical wireless data transmission system 1b according to the second embodiment of the present invention,
In this figure, the same components as those in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted. The first embodiment is a system for communicating between the two rooms 21 and 22 partitioned by the wall W. In the second embodiment, the wall W is used.
Instead of being present, two types of systems having different carrier frequencies are present in the same room 20.

That is, signal lights of frequencies f ₁ and f _{1 ′} are used between the modems MK _{1 to} MK _{3 and} MO ₃ , and the modems MK _{4 to} MK _{6 and} MO ₄ are used.
And communicating using the signal light of the frequency f ₂ and f _{2 'is} between. Even if the carrier frequencies are different from each other, the signal is demodulated by the demodulation unit 13. Therefore, by connecting the modem MO ₃ and the modem MO ₄ with the cable C or the like, the signal lights of the frequencies f _{1 and} f _{1 ′} are used. Frequency f from PC ₁ or PC _2
2, f 2 _'specifies the printer PR ₂ of the signal light used can be printed, and the frequency f _2, f 2 in the _opposite' frequency f ₁ from the personal computer PC ₃ of the signal light used _for, PC _4, f _{1 ''} Printer using signal light
Printing on PR ₁ is also possible.

In the system of the second embodiment, the cable C does not necessarily have to be used and both modems MO _3, MO
_{The 4} connectors 7 may be directly connected to each other. In addition, by arranging multiple couples such as modems MO _{3 and} MO ₄ for relay operation, communication in a vast room where a pair of modems are too far away from each other to receive light can be performed. It will be possible.

Next, a third embodiment of the system of the present invention will be described with reference to FIG. FIG. 7 is a system configuration diagram of an optical wireless data transmission system 1c according to the third embodiment of the present invention.
In this figure, the same components as those in FIGS. 3 and 6 are designated by the same reference numerals, and detailed description thereof will be omitted. In the first embodiment, there is one printer in each of the rooms 21 and 22 partitioned by the wall W, but in the third embodiment, a plurality of printers are installed. The directivity of the light receiving section 11 and the light emitting section 5 of the modems MO _{3 and} MO ₄ is preferably as wide as possible.

With this configuration, the personal computers PC _{1 to} PC ₅ can request printing from all the printers PR ₁ to PR ₄ regardless of the room. At that time, if you want to specify a specific printer to print out, specify “SYN + SYN + STX + STX + control code + communication partner + ETB + ETB + ... + ETB + ETB + FF + FF” as an example of special data (command). Use a pattern that cannot be found in normal print data, such as "+ ETX + ETX". Also, the fastest of the modems MK _3, MK _{6 to} MK ₈ without specifying-
Set the link with the modem that returned the ACKNLG response,
It is also possible to print out to a printer connected to it, in which case the modems MK _3, MK _{6 to} MK ₈ will wait a different random time each time they receive the -STROBE signal for link setting. It is designed to respond, so there is no risk of confusion with simultaneous responses from more than one modem.

In the above description, the Centro specification interface is used as the connector 7 and the bidirectional driver 8. However, the invention is not limited to this as long as the data input / output is performed by the control line handshake. Any interface may be used.

[0034]

Since the optical wireless data transmission system of the present invention is configured as described above, optical communication between two rooms partitioned by a wall, which has been impossible in the past, can be easily performed and the service area of the service area can be easily realized. It has excellent features such as expansion and an increase in the number of terminals that can be transmitted.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a modem which is a main part of a system of the present invention.

FIG. 2 is a basic system configuration diagram of a typical example of a conventional optical wireless data transmission system.

FIG. 3 is a basic system configuration diagram showing a first embodiment of an optical wireless data transmission system of the present invention.

FIG. 4 is a block diagram showing a detailed configuration of an interface that constitutes a modem.

FIG. 5 is a flowchart for explaining main operations in the system of the present invention.

FIG. 6 is a system configuration diagram showing a second embodiment of the system of the present invention.

FIG. 7 is a system configuration diagram showing a third embodiment of the system of the present invention.

[Explanation of Codes] 1a to 1c Optical Wireless Data Transmission System 2 Decoder (Decoder) 3 Frequency Converter 4 Data Processor 5 Light Emitting Section 6 Modulator 7 Connector 8 Bidirectional (I / O) Driver 9 Carrier Detection Circuit 11 Light Reception Part 12 Amplifier 13 Demodulator 14 Encoder (encoder) 20-22 rooms C cable CL, CL _1, CL ₂ Control lines MO _1- PR _4, MK _1- MK ₈ Modem PC _1- PC ₅ PC (word processor) PR ₁ ~ PR ₄ Printer W Wall.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H04L 12/28

Claims (4)

[Claims] 1. A system for performing wireless data transmission between a plurality of modems using light as a medium through each modem connected to a terminal or the like, wherein the plurality of modems output from other modems. A light receiving unit that receives light and converts it into an electric signal, a demodulator and a decoder that demodulate and decodes the electric signal, and the data decoded by the decoder is decoded and judged to be addressed to itself. A data processor that sends data to the terminal device through the cod connector or performs predetermined signal processing on data from the terminal device, an encoder and a modulator that respectively encode and modulate the output of the data processor, and a modulator A bidirectional drive that is connected between the light emitting unit that converts a transmission signal into light and outputs the light, and the data processor and the connector, and can switch the input / output direction by a control signal from the data processor. In addition to the configuration of the first modem including a bus, and the configuration of the first modem, by changing the carrier frequency of the signal received and photoelectrically converted by the light receiving unit, the light is output by supplying to the light emitting unit. An optical system comprising a second modem further including a frequency converter performing a relay operation, and having at least one set in the system in which two second modems are connected to each other via their connectors. Wireless data transmission system. 2. The second modem, which is connected to each other through an interface including a connector, is installed in different communication areas with a wall dividing the communication area separated from each other. Optical wireless data transmission system. 3. A data processor constantly monitors the data from the decoder and the state of the control signal at the interface and switches the modem to the transmitting side or the receiving side depending on which of the two is active first. The optical wireless data transmission system according to claim 1, wherein: 4. The optical wireless data transmission according to claim 1, wherein the first or second modem can set a communication partner according to a command (special data) from a terminal connected to the cable. system.