JPH09200079A - Data transmission method and data transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve transmission efficiency and to reduce power consumption by sending a broad band signal initially, measuring characteristic information of a transmission line to make inter-communication and setting a frequency characteristic and a transmission speed of a transmission signal based on the characteristic information. SOLUTION: A transmitter side sends an initial synchronizing signal at a full frequency band decided in advance in the initial stage of data transmission between data transmitters by the spread spectrum modulation system. A receiver side uses a spectrum detection/discrimination device 17 to detect a frequency amplitude characteristic of a synchronizing signal spread over a broad band to discriminate a notched band in the transmission band. A discrimination controller 20 sets an optimum transmission band width, a center frequency and a data transmission speed based on the band information to control variable band-pass filters 18, 19 and allows a spread modulator 16 to send various parameters to the transmitter side. The transmitter side sends data with various parameters according to the parameters sent from the receiver side. Thus, the transmission energy in the notched band is reduced to attain efficient data transmission.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission apparatus, and more particularly, to a data transmission apparatus using a spread spectrum modulation method for performing wideband transmission of transmission information in advance.

[0002]

2. Description of the Related Art A conventional spread spectrum modulation system basically employs a configuration as shown in FIG. In the figure, a spread modulator 16 modulates transmission data into a wideband spread spectrum modulated signal. The output of the spread modulator 16 is radiated as electromagnetic waves from the antenna 11 to space via the transmission high-frequency unit 14 and the transmission / reception switch 12. An electromagnetic wave to be received in space is converted into a high-frequency signal by the antenna 11 and applied to the despread modulator 15 via the transmission / reception switch 12 and the reception high-frequency unit 13. The despread demodulator 15 despread modulates the received high-frequency signal with the spread signal and demodulates the received data.

[0003] Spread-spectrum modulation is based on several tens to 100 of the transmission frequency bandwidth of data to be transmitted.
This is a method of transmitting data in a wide frequency band of about 0 times. Since the transmitting side performs frequency spread modulation with a spreading code, the transmission power density per unit frequency bandwidth is low and interference / interference to other communication systems is reduced. In addition, on the receiving side, the data transmission method has a characteristic that the influence of interference and interference from other communication systems is small due to sharp correlation characteristics due to frequency despread demodulation. In a conventional data transmission apparatus using the spread spectrum modulation method, there is an example of simplifying and increasing the speed of the receiving side, that is, the structure of the frequency despread demodulation. Data is transmitted by transmitting at the bandwidth.

On the other hand, the spread spectrum modulation system uses the CDM
There is a type of (code division multiplexing) system, which may be based on the premise that a plurality of users (subscribers) use the same transmission space, that is, the same frequency band, at the same time. In this case, the data transmission devices of a plurality of users interfere with each other.

[0005]

The following problems are raised in the data transmission apparatus based on the conventional spread spectrum modulation method.

The first problem is that when the same frequency band is used by a plurality of users (subscribers), it is difficult to avoid mutual interference.

The reason is that the power transmission in the frequency band in which the frequency characteristic is deteriorated does not mean that the frequency characteristic is deteriorated between other users (devices), and causes interference and interference, resulting in As a result, it becomes difficult to avoid mutual interference.

[0008] The second problem is that even when data transmission is performed via a transmission line whose amplitude frequency characteristic is not flat, unnecessary transmission power is sent out, and a third party who tries to eavesdrop on data transmission. Therefore, it is difficult to reduce the probability of being detected by the system and secure confidentiality.

[0009] The reason is that the power transmission in the frequency band where the frequency characteristics are degraded does not necessarily mean that the frequency characteristics are degraded by a third party (between devices) who intends to intercept and eavesdrop, and conversely, the signal power density Can be large, and it is difficult to reduce the probability of detection by a third party for eavesdropping and eavesdropping, and to ensure confidentiality.

A third problem is that even when data transmission is performed via a transmission line whose amplitude frequency characteristic is not flat, unnecessary transmission power is transmitted, and it is difficult to reduce the power consumption of the device. .

The reason is that, in the spread spectrum modulation method, several tens of
A wide frequency band of about 1000 times is used. On the other hand, the amplitude frequency characteristic of the transmission line between the transmitter and the receiver depends on the gain frequency characteristic of the transmitting and receiving antennas and the multiplicity generated in the actual transmission radio wave propagation space. Radio wave propagation characteristics are not flat due to path interference or the like, and a frequency band in which amplitude characteristics fall is generated. With respect to such frequency characteristics, the conventional data transmission apparatus transmits the signal while assuming that the frequency characteristics of the transmission path are uniform. Therefore, useless transmission power that cannot reach the receiving side sufficiently due to a drop in frequency characteristics is transmitted, and it is difficult to reduce the power consumption of the device.

According to the present invention, in order to suppress power transmission in a band with reduced amplitude frequency characteristics in a transmission path, it is possible to reduce signal transmission in a useless frequency band. Measure low power consumption.

[0013]

A data transmission method according to the present invention is a data transmission method for mutually transmitting and receiving data, comprising: transmitting a wideband signal at an initial stage of data transmission; Characteristic information is measured and mutually transmitted, and transmission is performed by setting a frequency characteristic and a data transmission rate of a transmission signal based on the frequency amplitude characteristic information.

In a data transmission apparatus for transmitting and receiving data to and from each other, an initial synchronization signal is mutually transmitted using an entire predetermined frequency band of the data transmission apparatus in an initial synchronization establishment stage. Transmitting, detecting a frequency amplitude characteristic from a received signal of the initial synchronization signal, and performing data transmission by reducing transmission energy in a frequency band in which the frequency amplitude characteristic has dropped.

[0015] When the frequency amplitude characteristics of the transmission path are partially reduced, it is preferable to reduce the data transmission speed and perform data transmission in a frequency band where the frequency amplitude characteristics are not reduced. Further, the data transmission device can be configured to perform data transmission by spread spectrum modulation.

Further, the data transmission apparatus of the present invention has a receiving system for demodulating a received signal with a despread demodulator via a variable band pass filter for reception, and a transmitting system for modulating transmission data with a spread modulator and transmitting. In a data transmission device comprising a transmission system for transmitting via a variable bandpass filter, a spectrum analyzer (spectrum detector / spectrum) for detecting a frequency amplitude characteristic of the received signal.
And a control unit that controls the pass characteristics of the variable band pass filter for reception to match the characteristics of the transmission line on the receiving side based on the frequency amplitude characteristic information obtained from the spectrum analysis unit. A decision control unit for superimposing the information on the transmission signal and controlling the characteristics of the variable band pass filter for transmission to match the characteristics of the transmission side transmission line based on the information of the frequency amplitude characteristics of the transmission side transmission line; and It is characterized by having.

At the initial stage of transmission / reception of data transmission, the transmitting side sends out an initial synchronizing signal over the entire predetermined frequency band, and the receiving side detects the initial synchronizing signal by the judgment control unit, and the spectrum detector / judder. The spectrum analysis of the received signal spread over a wide band is performed, the frequency characteristic information of the transmission line is output, the frequency characteristic information of the transmission line is input to the determination controller, and the variable band filter 1 and the variable band filter 2 are input. By controlling the center frequency of spread modulation and spread modulation speed and transmitting the specifications of the variable filter, etc. set on the receiving side to the transmitting side, data transmission suitable for the characteristics of the transmission line can be performed. ..

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a data transmission system according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. Referring to FIG. 1, the present embodiment also has the antenna 11, the basic configuration of the conventional spread spectrum modulation system.
Transmission / reception switch 12, reception high frequency unit 13, transmission high frequency unit 1
4, a despread demodulator 15 and a spread modulator 16; a spectrum detector / determiner 17; a variable bandpass filter 18; a variable bandpass filter 19;
have.

In FIG. 1, an antenna 11 radiates a high-frequency signal output of a data transmission device into space as an electromagnetic wave, and converts and inputs an electromagnetic wave to be received in space into a high-frequency signal. The transmission / reception switch 12 switches and connects the antenna to the transmission high-frequency unit during transmission and to the reception high-frequency unit during reception.

The receiving high frequency section 13 amplifies the signal from the antenna and outputs the amplified signal to the variable bandpass filter (1) 18 and the spectrum detecting / determining section 17, and the transmitting high frequency section 14 receives the variable bandpass filter (2). A) Amplify the output of 19 and output it to the antenna duplexer.

The variable bandpass filter (1) 18 can change the reception signal bandwidth of the reception signal under the control of the judgment controller 20, and passes a signal of a predetermined band. Similarly, the variable bandpass filter (2) 19 can change the transmission signal bandwidth of the transmission signal under the control of the judgment controller 20, and passes a signal of a predetermined band.

The despread demodulator 15 despread demodulates the received high-frequency signal with a spread signal and demodulates and outputs a received data output signal from a wideband spectrum modulated signal. Also,
The spread modulator 16 spread-modulates the transmission data input signal with the spread signal and outputs a wideband spectrum modulated signal.

The spectrum detector / determiner 17 receives a signal from the high-frequency receiver and outputs information on the signal strength of the input signal for each frequency band.

The decision controller 20 sets the pass band width of the variable bandpass filter (1) to be the whole of the preset use frequency band of the spread spectrum modulation when receiving the initial synchronization signal for data transmission. Controlling, and outputting pass band control information of the variable band pass filter (1) at the time of data reception based on output information of the spectrum detector / determiner,
And outputting a signal to be superimposed on a transmission signal of the data transmission device in order to transmit the passband control information to a transmission side.

FIG. 2 shows a spectrum detection / judgment section 17 and a variable bandpass filter (1) 18 according to an embodiment of the present invention.
2 shows a specific configuration of the variable bandpass filter (2) 19 and a connection configuration with the decision controller 20.

In the figure, variable bandpass filters 18, 19
And the spectrum detector / determiner 17 includes a pass band filter (1) 21, a pass band filter (2) 22, a pass band filter (3) 23, a pass band filter (4) 24, and a pass band. Band-pass filter (5) 25, pass-band filter (6) 26, amplitude detector (1) 27, amplitude detector (2) 28, amplitude detector (3) 29, pass-band filter (7) ) 30, a pass band filter (8) 31 and a pass band filter (9) 32.

In FIG. 2, the spectrum detector / judgment unit 17 includes a plurality of band-pass filters (4) to (6) for dividing the entire band of the received signal into a plurality of bands.
(4) to (6) and amplitude detectors (1) to (3) for detecting the level of the output. Output information.

The variable bandpass filter 18 is composed of a plurality of bandpass filters (1) to (3) and BPFs (1) to (3) for dividing the same band as the above band into a plurality of bands similar to the above. ,
The reception bandwidth of the reception signal can be changed under the control of the judgment controller 20, and a signal of a predetermined band is passed. The variable bandpass filter 19 changes the transmission bandwidth of the transmission signal under the control of the judgment controller 20 and transmits a signal of a predetermined band by the same bandpass filter configuration.

That is, in the case of FIG. 2, the band pass filter (1)
（(3), (7) 〜 (9) have different center frequencies of the passbands and have a bandwidth of one third of the predetermined reception band. When three band-pass filters are connected according to the connection information of the filters, they have a frequency characteristic of passing the entire transmission / reception bandwidth, and the whole band is rejected by switching the connection of each band-pass filter. It functions as a filter or a variable bandpass filter.

The decision controller 20 controls the pass bandwidth of the variable bandpass filter (1) 18 so as to have the entire bandwidth at the beginning of data transmission at the time of receiving the initial synchronization signal of data transmission, and also has a spectrum. A pass band for blocking the dip band of the variable band pass filter 1 at the time of data reception based on information such as a dip band of an internal frequency amplitude characteristic of the predetermined transmission band, which is a detection output from the detection / determination unit 17. , And a signal to be superimposed on the transmission signal of the own data transmission apparatus to send the passband control information to the data transmission apparatus of the other party, and outputs the signal to the spread modulator.

FIG. 3 is a block diagram showing a detailed configuration of the despread demodulator 15 and the spread modulator 16 in one embodiment of the present invention. Referring to FIG. 3, despread modulator 1
5 and the spread modulator 16 include a frequency converter (1) 34, a local oscillator (1) 35, a balanced modulator (1) 36, a spread signal generator (1) 37, a frequency converter (2) 39, and a local oscillator ( 2) 38, a balanced modulator (2) 41, and a spread signal generator (2) 40.

In FIG. 3, a variable bandpass filter (1) 18
The received high-frequency signal is frequency-converted by the output of the local oscillator in the frequency converter (1), and further de-spread by the spread signal from the spread signal generator (1) 37 in the balanced modulator (1) 36 to obtain the received data. Is output.

The transmission data signal is spread by the spread signal from the spread signal generator (2) 40 in the balanced modulator (2) 41 to output a modulated signal. The modulated signal is frequency-converted in the frequency converter (2) 39 by the output of the local oscillator (2) 38, and output to the variable bandpass filter 19 as a high-frequency signal.

The frequency converter 34 is a local oscillator (1) 35
, The received signal is frequency-converted into a processing frequency band required for despread modulation. Therefore, the local oscillator (1) 35 is controlled by the decision controller 20.

The balanced modulator 36 includes a frequency converter (1) 3
4 is input and balanced modulation is performed by the output signal of the spread signal generator 37 to demodulate received data. Therefore, in the spread signal generator (1) 37, the determination controller 20 controls the generated signal pattern of the spread signal and the generation speed thereof.
The balanced modulator (2) 41 receives the transmission data signal, and performs balanced modulation by the output signal of the spread signal generator (2) 40. For this reason, the spread signal generator (2) 40
0 controls the generated signal pattern and the generated speed.

The frequency converter (2) 39 converts the frequency of the spread modulation signal into a transmission frequency band based on the output signal of the local oscillator (2) 38. Therefore, the local oscillator (2) 39
Outputs a local oscillation signal of a required frequency to the frequency converter (2) under the control of the determination controller 20.

That is, according to the pass band control information (frequency amplitude characteristic of the transmission path) from the spectrum detector / determiner 17 detected at the initial stage of data transmission such as at the time of receiving the initial synchronization signal as described above. The data transmission device controls the receiving system so as to block the characteristics of the variable bandpass filter of the receiving system in accordance with the drop or the like. Also, in the transmission system of the own data transmission device, it is possible to realize necessary transmission in a transmittable band when passband control information is notified from a partner data transmission device due to a drop in transmission characteristics of a transmission path on the transmission side. The frequency converter controls the characteristics of the variable bandpass filter of the transmission system in accordance with the transmission bandwidth so as to block the characteristics in accordance with the drop, controls the transmission speed in order to generate a modulated signal in a transmittable band, To control the conversion frequency. For this purpose, the decision controller 20 controls the characteristics of the variable bandpass filter of the data transmission apparatus and the oscillation frequency of the local oscillator, and also controls the generated signal pattern of the spread signal generator and its generation speed. It should be noted that the same control as described above is performed by the determination controller in the partner data transmission device.

In FIGS. 1 and 3, the signal line through which the received data is supplied to the decision controller 20 is connected to the transmission line from the own data transmission device (transmission system) to the other device (reception system). This is a line for taking the passband control information received from the transmission system) into the decision controller 20. Also, in the figure, the signal line on which the transmission data is supplied to the determination controller 20 is data transmission start information,
This line takes in information such as initial synchronization information and the data rate of transmission data necessary for generating a spreading code.

As described above, in the embodiment of the present invention, the spectrum detector / determiner 17 divides the band necessary for the original data transmission into a plurality of bands based on the received signal and reduces the frequency amplitude characteristics. The decision controller 20 transmits the information to the partner data transmission device and uses the information to control the transmission band of the partner transmission system, etc., and obtains the same information from the partner data transmission device. Thus, the pass band of the receiving system of the own data transmission apparatus is controlled, and the frequency characteristics and the like of the variable band pass filter of the transmitting system are controlled.

Therefore, according to the present invention, at the initial stage of the transmission / reception of data transmission, the transmitting side transmits an initial synchronization signal in all predetermined frequency bands, and the receiving side detects the initial synchronization signal together with the detection of the initial synchronization signal. The spectrum analysis of the received signal spread over a wide band is performed, and the specifications of the transmission bandwidth, the center frequency, and the transmission speed can be optimally set according to the state of the transmission path.

[0042]

According to the data transmission method and apparatus of the present invention, as a first effect, the quality of data transmission can be improved.

The reason for this is that unnecessary transmission of power in a band is eliminated in data transmission, and interference between data devices is reduced even when a common frequency band is used.

As a second effect, the probability of being detected in data transmission is reduced, and confidentiality of communication is improved.

The reason is that unnecessary transmission of power is eliminated in data transmission, which makes it difficult for a third party to eavesdrop and intercept.

As a third effect, the power consumption of the data transmission device can be reduced.

The reason is that it is possible to reduce useless transmission power when the amplitude frequency characteristic of the transmission path is partially reduced.

[Brief description of drawings]

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

FIG. 2 shows a spectrum detector / determiner, a variable bandpass filter (1) and a variable bandpass filter (2) according to an embodiment of the present invention.
FIG. 4 is a block diagram showing the details of.

FIG. 3 is a block diagram illustrating details of a despread demodulator 15 and a spread modulator 16 according to an embodiment of the present invention.

FIG. 4 is a block diagram showing an example of a conventional data transmission system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 antenna 12 transmission / reception switch 13 reception high frequency unit 14 transmission high frequency unit 15 despread demodulator 16 spread modulator 17 spectrum detector / determiner 18 variable bandpass filter 1 19 variable bandpass filter 2 20 decision controller 21 band pass Filter (1) 22 Band-pass filter (2) 23 Band-pass filter (3) 24 Band-pass filter (4) 25 Band-pass filter (5) 26 Band-pass filter (6) 27) Amplitude detector (1) 28 Amplitude detector (2) 29 Amplitude detector (3) 30 Band-pass filter (7) 31 Band-pass filter (8) 32 Band-pass filter (9) 34 Frequency converter (1) 35 Local oscillator (1) 36 Balanced modulator (1) 37 Spread signal generator (1) 38 Frequency converter (2) 39 Local oscillator (2) 40 Balanced modulator (2) 41 Spread signal Generator (2)

Claims (5)

[Claims] 1. A data transmission method of mutually transmitting and receiving data, wherein a wideband signal is transmitted at an initial stage of data transmission, frequency amplitude characteristic information of a transmission line is measured by receiving the wideband signal, and the signals are mutually transmitted. A data transmission method characterized in that the frequency characteristic and the data transmission rate of a transmission signal are set on the basis of frequency amplitude characteristic information and transmission is performed. 2. In a data transmission device for transmitting and receiving data to and from each other, an initial synchronization signal is mutually transmitted using an entire predetermined frequency band of the data transmission device in an initial synchronization establishment stage, and an initial synchronization signal is received. A data transmission device, which detects a frequency amplitude characteristic from a signal, reduces transmission energy in a frequency band in which the frequency amplitude characteristic is degraded, and performs data transmission. 3. The data according to claim 2, wherein when the frequency-amplitude characteristic of the transmission line is partially degraded, the data transmission rate is reduced and data is transmitted in a frequency band in which the frequency-amplitude characteristic is not degraded. Transmission equipment. 4. The data transmission device according to claim 2, wherein the data transmission is performed by spread spectrum modulation. 5. A receiving system for demodulating a received signal by a despreading demodulator via a variable band filter for reception, and a variable band filter for transmission which modulates transmission data by a spread modulator. In a data transmission device comprising a transmission system for transmitting, a spectrum analyzer for detecting the frequency amplitude characteristic of the received signal, and a variable band filter for reception based on the frequency amplitude characteristic information obtained from the spectrum analyzer. While controlling the pass characteristic so as to match the characteristic of the receiving side transmission line, superimposing the information of the frequency amplitude characteristic on the transmission signal, and based on the information of the frequency amplitude characteristic of the transmitting side transmission line, a variable band filter for transmission. A data transmission device, comprising: a determination control unit that controls the characteristics of the wave filter to match the characteristics of the transmission-side transmission path.