JPH03289838A - Data communication system - Google Patents

Abstract

PURPOSE:To ensure sufficient S/N by arranging plural leakage cables connected in the lump to one transmission cable along a ceiling or a floor in a building in two-dimension so as to employ a solar battery for a data carrier as a power supply. CONSTITUTION:A transmission cable 14 is installed along a ceiling or a floor in a building and leakage cables 12-1-12-n are arranged in two-dimension via a distribution unit 16 provided to a branch connection point of the transmission cable 14. The branch side leakage cables 12-1-12-n receive 1/n of the transmission power from a transmission unit 18 by means of n-set of branching units 16 and an electromagnetic field based on the transmission power is generated around each of the leakage cables 12-1-12-n similarly. Data carriers 10-,10-2 receive and process the transmission signal from the transmission unit 18 with respect to the nearby leakage cables 12-1,12-2 and send a reply data, as required, to the leakage cables 12-1,12-2.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to data communication in which data is transmitted and received by wireless method between a data carrier carried by a person or object in a building, factory, etc. and fixed station equipment. Regarding the system.

[Conventional technology] In recent years, with the progress of office automation and factory automation, it has become desirable to centrally manage the movement of people and objects within buildings and distribute information and objects appropriately and quickly. There is.

For example, in a building system that has been proposed in recent years, people entering a building are required to carry an ID card with a communication function, and the building management system designates a person with a specific ID card to make a call. The idea is to send a message such as a person's current situation, or to request the transfer of personal data such as the person's preferred temperature and humidity for air conditioning control, for example.

For such a building system, it is possible to use a wireless data communication system that has been put into practical use in factory automation.

This wireless data communication system installs a data carrier on the product, so that the product itself has the information necessary for manufacturing and assembly, etc., and transmits data that passes through the positions of fixed station units placed along the production line. At this time, the contents of the data carrier are read in response to commands from the fixed station unit and necessary operations are performed.

[Problem to be solved by the invention] However, for example, more than 10,000 people in one building are provided with ID cards (data carriers), and data is sent and received from the fixed station side using a wireless method. In this case, the following problem arises.

First of all, data carriers are powered by solar cells that do not require battery replacement, so the power transmitted from the data carrier is weak, and the propagation distance from the data carrier to the fixed station varies as it is carried by people. Reliable communication quality cannot be obtained due to S/N problems in transmission to fixed stations.

Moreover, in the radio wave propagation space indoors such as a building, there is severe interference due to multiple reflections caused by installed objects, and normal communication can hardly be expected using normal data modulation and demodulation methods such as FSK and PSK.

The present invention was made in view of these conventional problems, and provides highly reliable communication between fixed station equipment and a large number of data carriers carried by a large number of people and objects indoors such as buildings. The purpose is to provide a data communication system that enables data transmission and reception.

[Means to solve the problem] In order to achieve this object, the present invention is constructed as follows.

In addition, the reference numerals in the drawings of the embodiments are also shown.

First, the present invention provides a plurality of data carriers 10-
1.10-2. ... and fixed station equipment installed in a structure such as a building, and data communication systems that transmit and receive data wirelessly between the fixed station equipment and data carriers are targeted.

For such a data communication system, the present invention provides a plurality of leaky cables 12 to 1 to 12-n arranged two-dimensionally distributed inside a structure and a plurality of leaky cables 12-1 to 12-n as fixed station equipment. 12n collectively connected together, and each leakage cable 12- from the transmission cable 14.
A distribution unit 16 provided at each branch connection point of the leaky cable that evenly distributes transmission power to 1 to 12-n, and a distribution unit 16 that is connected to one end of the transmission cable 14 and specifies the address of an arbitrary data carrier 10-1. a transmission unit 18 that modulates and transmits transmission data consisting of desired command data;
A receiving unit 20 for receiving and processing transmission data from a data carrier is provided.

On the other hand, each of the data carriers 10-1, 10-2°, . , a data processing section 24 that decodes the received data from the receiving circuit section 22 and displays a message or instructs to transmit the corresponding response data; and a data processing section 24 that modulates and transmits the transmission data based on the command of the data processing section 24. A transmitting circuit section 26 is provided.

Here, the transmitting circuit section 26 of the data carrier 10-1, 10-2°, etc. receives the frequency f using a pseudo-random sequence (PN sequence) generated in accordance with the bits of the transmission data. transmitting a carrier signal using spread spectrum modulation (SS) t,
On the other hand, the receiving unit 20 of the fixed station equipment uses the transmission cable 1
4 at the carrier frequency f of the data carrier. The demodulated signal sequence is demodulated using a local oscillation signal with a frequency that matches the frequency, and the correlation values are sequentially calculated between this demodulated signal sequence and the plurality of pseudorandom sequences 61 to Gm assigned to each of the plurality of data carriers, and the data bits are extracted from the correlation value output. Configure to restore.

Also, data carrier 10-1.10-2. . . . and the Gold sequence is used as a pseudo-random sequence for the receiving unit 20 of the fixed station equipment.

Further, the leaky cables 12-1 to 12-n are connected in a branch-like manner using the transmission cable 14 as a trunk, and are two-dimensionally distributed. Furthermore, the leaky cables 121 to 12-n can be connected in a branched manner using the transmission cable 14 as a trunk, and the leaky cables 12-1 to 12-n can also be arranged in a spiral shape. .

[Function] According to the data communication system of the present invention having such a configuration, the following effects can be obtained.

First of all, since multiple leaky cables collectively connected to a single transmission cable are arranged two-dimensionally along the ceiling or floor of a building, the propagation distance between data carriers carried by people or objects is limited. can be kept within a specified range depending on the distribution density of the leaky cable, and the maximum propagation distance between the data carrier and the leaky cable is usually around 2 m.
Even if the data carrier is powered by a solar cell or the like and the transmission power is weak, a sufficient S/N ratio can be ensured.

Furthermore, by adopting spread spectrum communication using pseudo-random sequences, especially gold sequences, for transmission from the data carrier to the leaky cable, it is possible to demodulate data bits with minimal errors from correlation calculations on the receiving side. Become.

In addition, because spread spectrum communication is performed by assigning different cold sequences to each data carrier, it is possible to keep the cross-correlation value of received sequences that are different from the cold sequence that is the standard for correlation calculation on the receiving side to a certain value or less. is guaranteed, and data can be reliably received and reproduced without causing interference even when data is transmitted from over 10,000 data carriers.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention.

In FIG. 1, the fixed station equipment will be explained as follows. One transmission cable 1 runs along the floor or ceiling of the building where the data communication system of the present invention is installed.
4 is laid, and a plurality of leakage cables 12-1.12 are connected to the transmission cable 14 via the distribution unit 16.
-2. ...12-n are branched and connected two-dimensionally. That is, the leakage cables 12-1 to 1 are connected to the transmission cable 14 through the distribution unit 16 provided at the branch connection point.
2-n are two-dimensionally arranged in a branch-like manner.

Leakage cables 12-1 to 12- for transmission cable 14
As shown in FIG. 2, the distribution unit 16 which branches and connects the input power P1, where n is the number of branches of the leakage cable,
P□X(1/n) is distributed to the leaky cable 12 side, and the remaining P, x ((
n-1)/n) is distributed to the output side.

Further, the distribution unit 16 also has a function as a circulator, and receives the signal power P from the leakage cable 12-1. is transmitted only in the direction of the transmission cable 14 on the output side. Therefore, from the distribution unit 16 to the next stage transmission cable 14, PO+ ((n 1) /n) xp 1
Electric power will be supplied.

Referring again to FIG. 1, a transmission unit 18 is connected to one end of the transmission cable 14. The transmitting unit 18 is a data carrier 10-1.10- which will become clear later in the description.
2. . . outputs a transmission signal based on command data specifying an address to the transmission cable 14. Specifically, the frequency f is determined by transmission data consisting of address and command data. The carrier signal is PSK modulated and transmitted.

1/n of the input power is supplied from the transmission power from the transmission unit 18 to the leakage cables 12-1 to 12n on the branch side by the n distribution units 16 shown in FIG. 2, and as a result, the leakage cables 12- The transmission power in the cables 1 to 12-n is approximately equal to each other, and the leaky cables 12-1 to 12-n can similarly generate an electromagnetic field based on the transmission power around them.

FIG. 3 is a block diagram of an embodiment of the transmitting unit 18 shown in FIG.

In FIG. 3, the transmitting unit 18 includes a parallel-to-serial converter 30,
It is composed of a PSK modulator 32, a carrier oscillator 34, and a power amplifier 36.

The parallel-to-serial converter 30 converts transmission data consisting of address data and command data provided as parallel data into serial data, and sequentially outputs the serial data to the PSK modulator 32. P.S.K.
As the modulator 32, for example, a two-phase modulator is used, and the frequency f from the carrier oscillator 34 is used. The carrier signal of data bit 0 has a phase of QO, and data bit 1 has a phase of 18.
It is phase modulated to 0° and output. Power amplifier 36 is PSK
The modulated signal from the modulator 32 is transmitted to n leaky cables 12-1 to 12-n by the distribution unit 16 shown in FIG.
The signal is amplified to a sufficient transmission power to form the necessary electromagnetic field and sent to the transmission cable 14.

Note that the PSK modulator 32 is not limited to a two-phase modulator, and any appropriate PSK modulator such as a four-phase modulator or an eight-phase modulator can be used. Furthermore, in order to further increase the data transmission speed, an amplitude phase modulation method (in which a predetermined number of bit strings are expressed as signal points in two-dimensional coordinates on the real and imaginary axes) is used.
QAM method) may also be used.

Referring again to FIG. 1, a receiving unit 20 is connected to the other end of the transmission cable 14. The receiving unit 20 includes a receiving circuit 38, a local oscillator 40, a demodulator 42, an A/D converter 44, a correlator 46, a Gold sequence generator 48, and a processor 50. The details of the receiving unit 20 will be made clear after explaining the data carrier side.

In the embodiment of FIG. 1, leakage cables 12-1 and 1
A case is shown in which there is a person who owns data carrier 10-1, 10-2 in the vicinity of 2-2. The data carrier 10-1, 10-2 is connected to the nearby leaky cable 12.
-1.12-2 receives and processes the transmitted signal by the electromagnetic field caused by the transmitted signal from the transmitting unit 18, and if necessary transmits response data to the leaky cable 12-1.12-2 side.

FIG. 4 is a block diagram of an embodiment of the data carrier 10-1 shown in FIG.

In FIG. 4, the data carrier 10-1 is composed of a receiving circuit section 22, a data processing section 24, and a transmitting circuit section 26.

First, the receiving circuit section 22 includes a receiving antenna 52, a receiving circuit 54, a PSK demodulator 56, and a straight curve converter 58.

That is, the receiving antenna 52 receives the transmission signal from the transmitting unit 18 due to the electromagnetic field from the nearby leaky cable 12-1, and after performing high frequency amplification and filtering in the receiving circuit 54, the PSK demodulator 56 converts the data bits into data bits. The signal is demodulated, converted into parallel data of a predetermined bit length by a straight-curve converter 58, and outputted to the data processing section 24.

The data processing section 24 is provided with a processor 60, an address setting circuit 62, a message display 64, and a data memory 66. When the processor 60 receives the received data from the direct curve converter 58, it compares the address data in the received data with the unique self-address set in the data carrier 10-1 by the address setting circuit 62, and determines whether the addresses match. Once obtained, the command data following the address data is decoded. If the decoded command data is message display data, the result of decoding the message is output to the message display 64, and a message such as ``Telephone'' is displayed together with the acoustic message. On the other hand, if the command data decoded by the processor 60 is a data transfer request to the data carrier, for example, the age of the person who owns the data carrier 10-1 stored in the data memory 66, which corresponds to the transfer request. Data such as the desired temperature for air conditioning control are read out, an address is added thereto, and the data is output to the transmission circuit section 26.

The transmitting circuit section 26 includes a parallel-to-serial converter 68, a Gold sequence generator 70, a carrier oscillator 72, a multiplier 74, a power amplifier 76, and a transmitting antenna 78. That is, the parallel transmission data consisting of the address and response data output from the processor 60 is converted into serial data by the parallel to serial converter 68, and the data bits are sequentially output to the Gold sequence generator 70. Gold sequence generator 70 is data carrier 10-1
For example, data bit 1 generates a specific gold sequence G1 pre-assigned to data bit 1, while data bit 0 stops the generation of gold sequence G1.

Here, the gold sequence is a code sequence generated using a preferred pair M sequence among M sequences in a pseudorandom sequence (PN sequence), and a preferred pair takes a small cross-correlation value such as -. A combination of M series. Therefore, when gold series are used, the value of cross-correlation between different gold series is guaranteed to be less than a certain value, and it is possible to guarantee a ratio of 37M to the peak value of autocorrelation between the same gold series. . In addition, the type of gold series is determined depending on the word length of the gold series, and if the maximum word length of the gold series currently discovered can be used, approximately 100,000 types of gold series can be prepared, so one It is possible to prepare 100,000 data carriers for buildings.

The one-word long Gold sequence G1 from the Gold sequence generator 70 is applied to a multiplier 74, where it is multiplied by the carrier signal of frequency f1 from the carrier oscillator 72 and outputs a spread spectrum signal.

That is, as shown in FIG. 5, the gold sequence signal from the gold sequence generator 70 is +1 at bit 1 and -1 at bit O.
By multiplying and matching this gold signal series by a carrier signal of frequency f1, a spread spectrum signal is generated that undergoes a phase inversion every time the gold series switches from +1 to -1 and from -1 to +1.

The spread spectrum signal from multiplier 74 is power amplified by power amplifier 76 and then transmitted from transmitting antenna 78 . Note that since the propagation distance from the transmitting antenna 78 to the leaky cable is usually about 2 meters, the spread spectrum signal from the multiplier 74 may be directly transmitted from the transmitting antenna 78 without providing the power amplifier 76.

Next, the receiving unit 20 of FIG. 1 will be explained in detail. The receiving circuit 38 of the receiving unit 20 receives the received signal from the transmission cable 14, and the receiving circuit 38 of the receiving unit 20 receives the received signal from the transmission cable 14,
The spread spectrum signal of carrier frequency f1 transmitted from 0-1.10-2 is extracted by filtering. The received signal from the receiving circuit 38 is given to a demodulator 42, which receives a local oscillation signal of the same frequency f1 as the carrier frequency on the data carrier side from the local oscillator 40, and demodulates the Gold sequence from the received signal. The received sequence obtained from the demodulator 42 is sampled by the A/D converter 44, converted to digital data, and input to the correlator 46.

Gold sequences 61 to Gm serving as a reference are sequentially supplied to the other correlator 46 from a gold sequence group generator 48. When a 1 word long received sequence is obtained in a shift register having a 1 word long received sequence, the correlator 46 sequentially inputs the gold sequences 01 to Gm from the gold sequence group generator 48 and sequentially performs a correlation calculation to calculate the correlation. Output the value to processor 50.

The processor 50 inputs an A/D signal to the shift register of the correlator 46.
At the stage when the received sequence of one word length is stored from the converter 44, a control command is given to the gold sequence group generator 48, and the gold sequence as a reference value is sent to the correlator in order of the gold sequence 61 to Gm. 46, and sequentially performs correlation calculations on all gold sequences G1 to Gm for one received sequence. For all the correlation calculations of the gold sequences G1 to Gm, if the correlation peak value output exceeding the specified value cannot be obtained from the correlator 46, the received sequence to the shift register of the correlator 46 is shifted by one bit, and the same process is performed. Repeat the calculation with the gold series 61 to Gm.

Received sequence and gold sequence 61 to Gm in correlator 46
If a correlation peak value that exceeds a predetermined value is obtained from the correlator 46 during the correlation calculation with Lock in state. In this locked state of the gold sequence, the correlator 46 is in the state of calculating autocorrelation for the gold sequence assigned to a specific data carrier, and the processor 50 demodulates data bit 1 with the correlation peak value output of the correlator 46, and Bit 0 is demodulated at the bit timing when no value output is obtained, thereby making it possible to reproduce the transmitted data from the data carrier.

Note that the correlation calculation in the reception unit 20 in FIG. 1 is performed by sequentially performing the correlation calculation by switching the Gold sequences 01 to Gm in the Gold sequence group generator 48. Gold generators that individually generate sequences 01 to Gm are provided, a plurality of correlators are provided corresponding to the number of gold generators, and the received sequences from the A/D converter 44 are input in parallel to the plurality of correlators. hand,
Correlation calculations between the gold sequences 61 to Gm and the received sequences may be performed in parallel. In addition, the actual correlator 46
The correlation calculation can be realized by, for example, a digital signal processor (DSP).

FIG. 6 is an explanatory diagram showing another embodiment of the two-dimensional arrangement of leaky cables in the present invention. In this embodiment, the leaky cable 12 is connected to the transmission cable 14 via the distribution unit 16. are arranged in a rectangular spiral shape, and compared to the case of leaky cables arranged straight in the form of branches as shown in Figure 1, the installation area for each leaky cable can be expanded, and the space between the spirals can be adjusted to suitably reduce leakage cables. Distribution density can be set. Of course, the spiral shape is not limited to the rectangular spiral shape shown in FIG. 6, but may be any suitable spiral shape such as a circular shape or an elliptical shape.

In addition, in the above embodiment, the data carrier 10-1
．． 10-2. ... employs spread spectrum communication for transmission to fixed station equipment, but spread spectrum communication may also be employed for communication from transmission unit 18 to data carrier 101.

Further, although the transmission unit 18 performs PSK modulation on the transmission data, it goes without saying that FSK modulation may also be used.

Furthermore, although the data carriers 10-1, 10-2, . . . send transmission data consisting of their own address and response data when transmitting data to fixed station equipment, it is not necessary to send address data.

That is, when the correlation peak value output is obtained from the correlator 46 on the receiving unit 20 side, the gold sequence group generator 4
The gold series from 01 to Gm is unique to the data carrier, and therefore the gold series from 01 to Gm
If you have address map data that indicates the address of the data carrier for the data carrier, you can immediately know the address of the data carrier from the gold sequence when the correlation peak value is obtained, and therefore include the address data in the data transmitted from the data carrier. There's no need.

[Effects of the Invention] As explained above, according to the present invention, a plurality of leaky cables collectively connected to one transmission cable are two-dimensionally arranged along the ceiling or floor in a building. Therefore, the propagation distance between a data carrier carried by a person or object can be kept within a specified range depending on the distribution density of the leaky cable, and the maximum propagation distance between the data carrier and the leaky cable is usually around 2 meters. Therefore, by using a solar cell as a power source for the data carrier, a sufficient S/N ratio can be ensured even if the transmission power is weak.

In addition, by adopting spread spectrum communication using pseudo-random sequences, especially gold sequences, for transmission from data carriers to fixed station equipment, it is possible to demodulate data bits with minimal errors from correlation calculations on the receiving side. becomes.

Furthermore, spread spectrum communication from data carriers using the gold sequence guarantees that the cross-correlation value on the receiving side can be kept below a certain value, without causing bit errors in transmission data from a large number of data carriers.
Transmitted data from a data carrier can be reliably reproduced.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention; Fig. 2 is a functional explanatory diagram of a distribution unit of the present invention; Fig. 3 is a block diagram of an embodiment of a transmitting unit of the present invention; Fig. 4 is a data carrier of the present invention. FIG. 5 is an explanatory diagram of spread spectrum modulation of a data carrier according to the present invention; FIG. 6 is an explanatory diagram showing another embodiment of the two-dimensional arrangement of leaky cables according to the present invention. In the figure, 10-1.10-2: Data carrier 12. 12-1 to 12-n: Leakage cable 14: Transmission cable 16: Distribution unit 18: Transmission unit 20,: Receiving unit 22: Receiving circuit section 24: Data Processing section 26: Transmission circuit section 30.68: Parallel to serial converter 32: PSK modulator 34.72: Carrier oscillator 36.76: Power amplifier 38.54: Receiving circuit 40: Local oscillator 42: Demodulator 44: A/ D converter 46: Correlator 48: Gold sequence group generator 50.60: Processor 52: Receiving antenna 56: PSK demodulator 58: Direct curve converter 62 Near address setting circuit 64: Message display 66: Data memory 70: Gold Sequence generator 74: Multiplier 78: Transmission antenna

Claims (1)

[Scope of Claims] (1) Consists of a plurality of portable data carriers and fixed station equipment installed in a structure such as a building, and transmits and receives data wirelessly between the fixed station equipment and the data carriers. In a data communication system, the fixed station equipment includes: a plurality of leaky cables that are two-dimensionally distributed within a structure; a transmission cable that collectively connects the plurality of leaky cables; a distribution unit provided at each branch connection point of the leaky cable that distributes transmission power equally from the cable to each leaky cable; a transmitting unit that modulates and transmits transmission data consisting of; a receiving unit that receives and processes transmission data from a data carrier; a receiving circuit section that receives and demodulates the received data; a data processing section that decodes the received data from the receiving circuit section and displays a message or instructs transmission of corresponding response data; transmission based on the command of the data processing section. A data communication system comprising: a transmitting circuit unit that modulates and transmits data; and; (2) In the data communication system according to claim 1, the transmission circuit section of the data carrier spread spectrum modulates the carrier signal using a pseudorandom sequence generated according to the bits of the transmission data, and transmits the signal, and the reception The unit demodulates the received signal from the transmission cable with a frequency signal matching the carrier frequency signal of the data carrier, and sequentially converts between the demodulated signal sequence and the plurality of pseudorandom sequences assigned to each of the plurality of data carriers. A data communication method characterized by calculating a correlation value and restoring data bits from the output of the correlation value. (3) The data according to claim 2, characterized in that a gold sequence is used as the pseudo-random sequence used in the data carrier and the receiving unit. (4) The leakage cable is arranged in a branch shape with the transmission cable as the trunk. 2. The data communication system according to claim 1, wherein the data communication system is connected and distributed two-dimensionally. (5) The data communication system according to claim 1, wherein the leaky cables are connected in a branch shape using the transmission cable as a trunk, and each leaky cable is arranged in a spiral shape.