JPH09261288A - Data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize a data transmission efficiency and a radio frequency by using a pilot signal in time division for frequency deviation correction of a local oscillation frequency and transmission of low speed data. SOLUTION: A synthesizer 3 synthesizes a carrier signal being a pilot signal in time division by a modulator 2 or a monitor control signal obtained by modulating the pilot signal by low speed data, and main data phase-modulated together with a synchronization information signal and the synthesized data are sent from a transmitter 4 and an antenna 5 as a radio wave in a transmission system TX. Furthermore, in a reception system RX, a reception signal from an antenna 6 and a receiver 7 is distributed by a distributer 8, a demodulator 10 extracts a pilot signal to correct a frequency deviation in a local oscillating frequency and demodulates the signal to provide an output of reception low speed data Srb. Furthermore, a demodulator 9 provides an output of reception main data Sra. A control circuit 21 controls the time division timing for the pilot signal and the reception low speed data Srb in the demodulator 10 so as to be in matching with the timing of the transmission system TX.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transmission system for correcting frequency deviation of a local oscillation frequency and transmitting data by using a pilot signal.

[0002]

2. Description of the Related Art Conventionally, in digital transmission using a wireless line, a pilot signal is used to improve the transmission function and performance. For example, as a measure against fading of a wireless line, transmission power is controlled based on the level of a received pilot signal. Similarly, the level of the received pilot signal is also used for diversity switching control of the wireless line,
The switching control is performed. Further, the pilot signal is also used for transmission of the supervisory control signal, and the received pilot signal is also used for the improvement of the synchronization performance and the frequency deviation correction for the control.

In such an operation, the pilot signal for correcting the frequency deviation is used for correcting the frequency deviation between the local oscillators on the transmitting side and the receiving side and the frequency deviation due to the Doppler shift generated in the mobile communication. This pilot signal is a non-modulated and single-frequency sine wave in order to improve the correction accuracy. That is, data transmission by the pilot signal is not performed.

As this kind of digital transmission, Japanese Patent Laid-Open No. 61-
There is known a slave station discrimination method for a multidirectional digital communication network described in Japanese Patent Publication No. 59020. In this conventional example, a supervisory control signal required in each slave station and master station is used instead of a normal pilot signal, without reducing the capacity of the communication channel,
The child station is being identified. As a result, the pilot signal is monitored and controlled without occupying one channel.

[0005]

However, in the above-mentioned conventional example, the pilot signal is used only for the correction of the frequency deviation, the transmission efficiency is poor, and the radio frequency cannot be effectively used. Further, in order to improve the transmission efficiency, data transmission may be performed using a pilot signal for frequency deviation correction. In this case, however, since the pilot signal is modulated with data, the frequency component of the pilot signal is simple. There is a drawback that the deviation correction accuracy deteriorates because it is not a sine wave of one frequency.

Further, in the latter conventional example of Japanese Patent Laid-Open No. 61-59020, since the supervisory control signal is used as a normal pilot signal, the effective use of the radio frequency can be achieved, but the same as the above-mentioned conventional example. In addition, since data transmission using pilot signals cannot be performed, improvement in data transmission efficiency cannot be expected.

The present invention solves the problems in the prior art as described above, in which a time-division pilot signal is corrected for frequency deviation of the local oscillation frequency, and a low-speed data such as a supervisory control signal and synchronization information is acquired. It is an object of the present invention to provide a data transmission system which is used for transmission, has improved data transmission efficiency, and enables effective use of radio frequencies.

[0008]

In order to achieve the above object, the present invention according to claim 1 transmits a pilot signal between a transmission system and a reception system to perform frequency deviation correction of local oscillation frequency and data transmission. A data transmission system that
Oscillation means for oscillating a carrier signal serving as a pilot signal in the transmission system, modulation means for modulating the pilot signal from the oscillation means with data, and transmission for performing control for time-divisionally inputting data to the modulation means And a division control means,
Further, the receiving system includes carrier wave extracting means for extracting a pilot signal transmitted by the transmitting system, demodulating means for demodulating data from the received signal transmitted by the transmitting system, and a carrier wave in synchronization with the time division timing of the transmitting system. The extraction means outputs the pilot signal and the demodulation means outputs the data. The reception time division control means is provided.

According to another aspect of the data transmission system of the present invention, each of the transmission system and the reception system is provided with a wireless transmission / reception means, and a pilot signal and a modulation signal obtained by modulating the pilot signal with data are time-divided through the wireless transmission / reception means. Is configured to wirelessly transmit and receive.

According to a third aspect of the present invention, there is provided a data transmission system, wherein the transmission system is provided with main data modulating means for modulating main data.
And, the main data demodulating means is provided in the receiving system, the main data from the main data modulating means is combined with the low speed data from the modulating means and transmitted, and the low speed data is demodulated by the demodulating means of the receiving system, and, The main data demodulation means demodulates the main data.

According to a fourth aspect of the data transmission system, the modulation is phase-modulated.

According to a fifth aspect of the present invention, there is provided a data transmission system configured to transmit a supervisory control signal for supervising and controlling a transmission system and a synchronization information signal as low speed data.

The data transmission system having such a configuration is
A transmission system wirelessly transmits main data together with a carrier signal serving as a time-division pilot signal, a monitor control signal obtained by modulating a pilot signal with low-speed data, a synchronization information signal, or the like. Further, the receiving system extracts the pilot signal from the received signal from the transmitting system to correct the frequency deviation of the local oscillation frequency, and demodulates and outputs the low speed data and the main data.

Therefore, the time-divided pilot signal can be used for correcting the frequency deviation of the local oscillation frequency and for transmitting low-speed data such as the supervisory control signal and the synchronization information, thereby improving the transmission efficiency and the effective radio frequency. It becomes available.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the data transmission system of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of a data transmission system of the present invention. The example of FIG. 1 has a radio transmission system TX and a radio reception system RX. The wireless transmission system TX includes a modulator 1 that modulates the transmission main data Sta, a modulator 2 that modulates the transmission low-speed data Stb, a transmission main data Sta from the modulator 1 and a pilot signal from the modulator 2. And a combiner 3 for combining and outputting the low-speed transmission data Stb.

Further, it has a transmitter 4 for transmitting the high frequency power obtained by converting the synthesized output signal of the synthesizer 3 into a predetermined frequency, and an antenna 5 for transmitting the high frequency power from the transmitter 4. The modulator 2 also outputs a control circuit 11 that outputs a gate signal Stg for time-divisionally transmitting a pilot signal or low-speed data, and an oscillation signal for the control circuit 11 to output a gate signal Stg. It has a highly stable oscillator 15.

The modulator 2 is an AND circuit 2a for transmitting the low speed transmission data Stb based on the gate signal Stg.
And an oscillator 2b for transmitting a carrier signal which is a pilot signal. Further, it has a multiplier 2c that modulates a carrier signal (pilot signal) with transmission low-speed data Stb that is an AND output, and a bandpass filter (BPF) 2d that extracts and outputs a predetermined frequency band of this multiplier 2c. ing.

The radio reception system RX has an antenna 6 for receiving a transmission wave from the radio transmission system TX and a receiver 7 for outputting an intermediate frequency signal obtained by frequency-converting a reception signal from the antenna 6. . Further, the divider 8 that divides the intermediate frequency signal output from the receiver 7 into two, the demodulator 9 that outputs the reception low-speed data Srb obtained by demodulating the signal from the divider 8 and the reception main data Sra are demodulated and output. Demodulator 1
0.

Further, a control circuit 12 which outputs a reception status Srs to the radio reception system RX and which controls the transmission low-speed data Stb of the radio transmission system TX or time division of the pilot signal, and this control circuit. Switch 13 for transmitting the pilot signal received by the switching signal from 12. Further, it has a frequency correction circuit 14 for sending the frequency correction information signal Src to the demodulators 9 and 10 based on the pilot signal from the switch 13, and a highly stable oscillator 16 for sending an oscillation signal to the control circuit 12. .

The demodulator 10 of the radio reception system RX has a BPF 10a for extracting and outputting a predetermined frequency band of the output signal from the distributor 8 and a carrier wave regenerating circuit 10b for regenerating the carrier wave signal. . Further, a detector 10c that detects the signal from the BPF 10a with the carrier signal from the carrier recovery circuit 10b, a low-pass filter (LPF) 10d that extracts the low band of the detection signal of the detector 10c, and L
Timing recovery circuit 10e and determination circuit 10f for demodulating the received low speed data Srb from the detection signal from the PF 10d.
Are provided.

Next, the operation of this embodiment will be described. FIG. 2 is a diagram showing signals and timings in the operations of the wireless transmission system TX and the wireless reception system RX. In the wireless transmission system TX, the transmission main data Sta is phase-modulated by the modulator 1. In the modulator 2, the transmission control low-speed data Stb such as the supervisory control signal and the synchronization information shown in FIG. To do. In the modulator 2, the transmission low-speed data Stb is input to one end of the AND circuit 2a, and the gate signal Stg from the control circuit 11 is input to the other end.

The gate signal Stg shown in FIG. 2B becomes low (L) level or high (H) level in a time division manner.
The AND circuit 2a outputs the transmission low-speed data Stb when the gate signal Stg is at the low level (data transmission is possible), and stops the output when the gate signal Stg is at the high level (data transmission is prohibited).

Therefore, the multiplier 2c outputs the gate signal St.
When g is a period during which data can be transmitted, the carrier wave signal (pilot signal) from the oscillator 2b is phase-modulated with the low-speed transmission data Stb and output. In the data transmission prohibited section, the carrier wave signal (pilot signal) from the oscillator 2b is transmitted without modulation.

That is, during the transmission of the transmission low-speed data Stb, the phase modulation signal is transmitted from the modulator 2. Further, the transmission signal during non-transmission of the transmission low-speed data Stb is unmodulated, a sine wave having a single frequency is output, and becomes a pilot signal for frequency deviation correction. After the phase modulation signal and pilot signal from the modulator 2 and the phase modulation signal from the modulator 1 are combined by the combiner 3, the transmitter 4, the antenna 5
2 (c) to the radio receiving system RX by the radio line through
Is transmitted as a transmission signal Stx.

In the radio reception system RX, the reception signal received by the antenna 6 is divided into two by the receiver 7 and the distributor 8 and input to the demodulators 9 and 10. The demodulator 9 performs demodulation corresponding to the modulator 1 of the wireless transmission system TX and sends out the reception main data Sra. Further, the demodulator 10 performs demodulation corresponding to the modulator 2 of the radio transmission system TX and sends out the transmission low-speed data Stb, and also extracts the carrier wave signal (pilot signal).
The frequency deviation of the local oscillation frequency is corrected by.

In this case, the control circuit 11 of the radio transmission system TX
Controls the transmission of the transmission low-speed data Stb on a time-division basis, and transmits the transmission status Sts to the wireless reception system Rx through a transmission system (not shown). The control circuit 12 of the radio reception system RX demodulates the transmission low-speed data Stb in synchronization with the control of the transmission status Sts from the control circuit 11 of the radio transmission system TX, and
The reception (period) is notified to the terminal side (not shown) through the reception status Srs.

In the demodulator 10 of the radio receiving system RX,
The transmission low-speed data St based on the control signal of the control circuit 12
During the reception period of b, the demodulation is performed and the reception low speed data Srb is sent to the terminal side not shown. During the non-reception period of the reception low-speed data Srb, a pilot signal of a single frequency is extracted without modulation, and the frequency correction circuit 14 causes the demodulators 9 and 10 to operate.
The frequency deviation correction information Src is sent to the carrier recovery circuit 10b.

In this operation, the output signal from the distributor 8 is B
A predetermined frequency band is extracted by the PF 10a and input to the detector 10c. The detector 10c demodulates the carrier signal from the carrier recovery circuit 10b. At this time, the switch 13 receives the control signal from the control circuit 12 of the radio reception system RX during the pilot signal reception period shown in FIG.
As shown in (e), the BPF 10a is switched to be conductive.
The pilot signal from is input to the frequency correction circuit 14.

The frequency correction information signal Src from the frequency correction circuit 14 is input to the demodulator 9 and its detection is performed with the signal of the local oscillation frequency whose frequency deviation has been corrected. Similarly, in the demodulator 10, the frequency correction information signal Src from the frequency correction circuit 14 is input to the carrier recovery circuit 10b, the frequency deviation corrected signal of the local oscillation frequency is input to the detector 10c, and the detection is performed. Done. After this, the demodulated signal is the LPF 10d, the low frequency band is extracted, the received low speed data Srb is demodulated through the timing recovery circuit 10e and the determination circuit 10f, and sent to a terminal (not shown).

In this embodiment, the wireless transmission / reception has been described, but the wired transmission / reception also operates in the same manner, and the effects thereof can be obtained.

[0031]

As is apparent from the above description, according to the data transmission system of the present invention, the transmission system wirelessly transmits the main data together with the time-division pilot signal or the low-speed data obtained by modulating the pilot signal. are doing. Also,
The receiving system extracts the pilot signal from the received signal from the transmitting system to correct the frequency deviation of the local oscillation frequency, and demodulates and outputs the low-speed data and main data. It can be used for transmission of low-speed data such as a supervisory control signal and synchronization information together with the correction of frequency deviation of the frequency, the transmission efficiency is improved, and the radio frequency can be effectively used.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a data transmission system of the present invention.

FIG. 2 is a diagram showing signals and timing in operations of a transmission system and a reception system of the embodiment shown in FIG.

[Explanation of symbols]

 1, 2 modulator 2a AND circuit 2b oscillator 2c multiplier 3 synthesizer 4 transmitter 7 receiver 9,10 demodulator 10b carrier wave recovery circuit 10c wave detector 10e timing recovery circuit 10f determination circuit 11, 12 control circuit 13 switch 14 frequency Correction circuit 15, 16 Highly stable oscillator RX wireless reception system TX wireless transmission system

Claims (5)

[Claims] 1. A data transmission system for transmitting a pilot signal between a transmission system and a reception system to perform frequency deviation correction of local oscillation frequency and data transmission, wherein a carrier signal serving as a pilot signal is supplied to the transmission system. The receiving means includes an oscillating means for oscillating, a modulating means for modulating a pilot signal from the oscillating means with data, and a transmission time division controlling means for controlling the time division input of the data to the modulating means. A carrier wave extraction means for extracting a pilot signal transmitted by the transmission system, a demodulation means for demodulating data from a received signal transmitted by the transmission system, and a synchronization means for synchronizing the time division timing of the transmission system. Reception time division control means for controlling the carrier wave extraction means to output a pilot signal and the demodulation means to output data. Data transmission system. 2. The transmission system and the reception system are each provided with a wireless transmission / reception unit, and the pilot signal and a modulation signal obtained by modulating the pilot signal with data are wirelessly transmitted / received through the wireless transmission / reception unit. The data transmission system according to claim 1. 3. The transmission system is provided with main data modulation means for modulating main data, and the reception system is provided with main data demodulation means, so that the main data from the main data modulation means is transmitted at low speed from the modulation means. 2. The data transmission system according to claim 1, wherein the data transmission system synthesizes the data together with the data, transmits the demodulation means to demodulate the low speed data, and the main data demodulation means demodulates the main data. 4. The data transmission system according to claim 1, wherein the modulation is phase modulation. 5. The data transmission system according to claim 1, wherein a supervisory control signal for supervising and controlling a transmission system and a synchronization information signal are transmitted as the low-speed data.