JP2000041028A - Radio transmission equipment, reception equipment and transmission-reception system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate errors comparatively for a long time without expanding circuit scale and to improve reliability in transmission. SOLUTION: On the side of transmission, a timing generator 4, memory 2 and error correct code/synchronizing pattern adder 3 are provided, the same information data are read out more than twice by the clock of a frequency higher than the double frequency of clock of an information source 1, and these information data are sent out while adding an error detection code or the like. Thus, even the comparatively long error can be compensated. On the side of reception, an error detector and a characteristic varying means for varying reception characteristics are provided, the reception characteristics are switched based on the output of the error detector and even when transmission characteristics are remarkably changed, these characteristics can be followed up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio transmission apparatus, a reception apparatus, and a transmission / reception system suitable for use in, for example, data communication using a line or the like in which the state of a transmission medium is unstable and transmission characteristics change greatly.

[0002]

2. Description of the Related Art When transmitting audio and video signals to distant places, radio waves, infrared rays, power lines and the like have conventionally been used as transmission media, and there are cases where signals are directly modulated and transmitted. Well known. However, when performing transmission by performing such direct modulation, it is easily affected by noise and the state of the line, and it has been difficult to maintain a high-quality transmission signal. It is possible to improve the characteristics to some extent by adaptively switching the reception characteristics to these inhibiting factors as needed, but when using such a method, it is affected by the disturbance at the time of switching, This is a problem in applications where continuity is important. In order to solve such a problem, it is possible to improve the above-mentioned problem by digitizing audio and video signals, transmitting the digital signal with an error correction code added, and performing error correction on the receiving side.

[0003]

However, in the case of the above-described method of adding an error correction code, if an attempt is made to compensate for a relatively long time error, for example, several hundred milliseconds, the circuit scale becomes enormous. There is a problem that it is not realistic in terms of size and cost.

Accordingly, an object of the present invention is to compensate for an error for a relatively long time without increasing the circuit scale, and to improve the reliability in transmission even in an environment where the transmission characteristics change drastically. It is an object of the present invention to provide a wireless transmission device, a reception device, and a transmission / reception system that can perform the transmission.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an invention according to claim 1 is a wireless transmission apparatus for transmitting information data supplied from an information source, which is twice as fast as the information source. Timing generating means for generating a clock, storage means for storing information data from an information source and reading out the stored information data based on the clock, an error detection code and a synchronization pattern and frame identification for the information data A wireless transmitting apparatus comprising: an information adding unit that adds a code; and a transmitting unit that modulates an output of the information adding unit and transmits information data at least twice in different time zones.

According to a second aspect of the present invention, there is provided a receiving apparatus for reproducing information data from a received signal, a demodulating means for demodulating the received signal, and a timing for generating a clock from the signal obtained by the demodulating means. Generating means;
A storage unit configured to store the demodulated signal and read the stored signal based on a clock; an error detection unit configured to detect an error in a frame output from the demodulation unit; Receiving means for varying a receiving characteristic by using the characteristic information, and an output means for selecting and outputting an error-free frame among the demodulated frames of the same information data. .

Further, according to a third aspect of the present invention, in a transmission / reception system for transmitting information data supplied from an information source, receiving a transmitted signal and reproducing the information data, the transmission speed is twice or more that of the information source. Timing generating means for generating a clock of the same type, storage means for storing information data from an information source and reading out the stored information data based on the clock, an error detection code, a synchronization pattern and a frame for the information data. Information adding means for adding an identification code, transmitting means for modulating an output of the information adding means and transmitting information data at least twice in different time zones, and demodulation for receiving and demodulating a signal transmitted by the transmitting means Means, timing generation means for generating a clock from the signal obtained by the demodulation means, and storing the demodulated signal. Storage means adapted to read out the detected signal based on the clock, error detection means for detecting an error in the frame of the output of the demodulation means, and characteristic variable means for varying the reception characteristic based on the output of the error detection means. And an output unit for selecting and outputting an error-free frame from the demodulated frames of the same information data.

According to the present invention, on the transmitting side, the timing generating means, the storing means, and the information adding means are provided, and the same information data is transmitted twice by a clock having a frequency more than twice the frequency of the information source clock. Since the information data is read out and transmitted with an error detection code or the like added to the information data, even if an error occurs during transmission, the receiving side selects and outputs a normal data portion. be able to.

Further, according to the present invention, on the receiving side, the error detecting means and the characteristic varying means for varying the receiving characteristic are provided, and the receiving characteristic is switched based on the output of the error detecting means. Can be adjusted to the optimum reception characteristic following the large change of

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG.
Shows a configuration of a wireless transmission device according to the present invention,
FIG. 2 shows a configuration of a receiving apparatus according to the present invention. In addition,
FIG. 3 shows signal states and signal waveforms at respective parts of the wireless transmission device and the reception device shown in FIGS. 1 and 2.

As shown in FIG. 1, the radio transmitting apparatus comprises an information source 1, a memory 2, an error detection code / synchronization pattern adder 3,
It comprises a timing generator 4, a modulator 5, a carrier oscillator 6, and the like. The information source 1 has digitized information data, and the information data output from the information source 1 is supplied to the memory 2. For example, the information data output from the information source 1 is digital data or the like obtained by encoding an audio signal, but may be other data and is not particularly limited. Further, from the information source 1, for example, a first clock for dividing information data into a predetermined information amount unit is supplied to the memory 2 and also to the timing generator 4.

In the memory 2, information data from the information source 1 is sequentially stored in a predetermined information amount unit based on a first clock. On the other hand, in the timing generator 4,
Based on the first clock, a second clock having a frequency that is twice or more the frequency of the first clock is generated, and the second clock is supplied to the memory 2 and the error detection code / synchronization pattern adder 3.

In the memory 2, information data which has already been written is read twice in a predetermined order based on the second clock. Specifically, in the memory 2, for example, after reading out two pieces of information data continuous on the time axis, the same two pieces of information data are read out once again. , Two pieces of information data continuous on the time axis are read twice each. That is, by this reading process, the information data is compressed to 以上 or more on the time axis, and the same information data is arranged again in the idle time obtained by compressing the information data. The information data thus read is supplied to the error detection code / synchronization pattern adder 3.

In the error detection code / synchronization pattern adder 3, various data are added to the information data according to a predetermined rule based on the second clock, and a baseband signal S1 in a predetermined transmission form is formed. You. Specifically, as the additional information, for example, an error detection code such as a cyclic code, a synchronization pattern, and a frame identification code are added for each frame, and a predetermined transmission mode is set.

FIG. 3A shows an arrangement relationship on the time axis of each frame present in the baseband signal S1 formed in the error detection code / synchronization pattern adder 3, and FIG. 3B shows an arrangement relationship of each data in the frame. Is shown. FIG. 3A
In the above, the second read data for the same information data is marked with '.

As shown in FIG. 3A, after the n-th information data and the (n + 1) -th information data which are continuous on the time axis are read once by the reading process of the memory 2,
It is read again, and is framed in such a form that it is read alternately twice in units of two. As shown in FIG. 3B, a synchronization signal 21, a frame identification signal 22, information data 23, and an error detection code 24 are arranged from the beginning of the frame.
Since a frame identification code is added for each frame,
It is configured to be able to identify in frame units.

The baseband signal S1 in the predetermined transmission form is supplied to one input terminal of the modulator 5. A carrier from a carrier oscillator 6 is supplied to the other input terminal of the modulator 5, and the carrier is modulated by the baseband signal S1. The modulated output is taken out as a wireless signal via the output terminal 7, and is sent out via a predetermined output unit such as an antenna if the transmission medium is a radio wave, an LED if the transmission medium is an infrared ray, or an insulation transformer if the transmission medium is a power line. As a modulation method, QPSK (Quadrature P
hase Shift Keying), FSK (Frequency Shift Keyin)
g), various methods such as QAM (Quadrature Ampltude Modulation) or FM (Frequency Modulation) can be used according to the mode of the system, and there is no particular limitation.

As shown in FIG. 2, the receiving device comprises a high-frequency amplifier filter 11, a detector 12, an error detector 13, a memory 1
4, a timing generator 15, a characteristic switching circuit 16, and the like. The signal transmitted from the above-described wireless transmission device is received, converted into a wireless signal S2 by a converter corresponding to the transmission medium, and supplied to an input terminal indicated by 17 in FIG. The radio signal S2 is supplied to the high frequency amplification filter 11 via the input terminal 17.

The high frequency amplifier filter 11 has an amplifying and filtering function and a control terminal.
The reception characteristics are switched according to the state of the control terminal, a signal of a desired frequency is selected, and the selected signal is amplified and output. The output of the high-frequency amplifier filter 11 is the detector 12
Supplied to

In the detector 12, demodulation processing corresponding to the processing performed on the transmission device side is performed, and a baseband signal is formed as a demodulated output. This baseband signal is supplied to the error detector 13 and also to the timing generator 15.

In the timing generator 15, the detector 1
A synchronization pattern is extracted from each frame of the baseband signal from the second and the first clock, and a second clock having a frequency twice or more the frequency of the first clock is generated based on the extracted synchronization pattern. The second clock is supplied to the error detector 13 and also to the memory 14.
Further, the first clock is supplied to the memory 14 and is extracted via the output terminal 19.

On the other hand, the error detector 13 performs error detection based on an error detection code added for each frame,
An error occurrence signal S3 according to the detection result is formed. For example, when an error is detected, a high-level error occurrence signal S3 is formed in the error detector 13, and this signal S3 is supplied to the characteristic switching circuit 16. Further, the error detector 13 invalidates the frame in which the error is detected,
Only information data of a normal frame in which no error is detected is extracted to form an output signal S5.
4

The characteristic switching circuit 16 forms a switching signal S4 for switching reception characteristics based on the error occurrence signal S3 from the error detector 13. The switching signal S4 formed in the characteristic switching circuit 16 is supplied to the control terminal of the high-frequency amplification filter 11 described above, and the reception characteristic of the radio signal is switched to an optimal state.

The information data from the error detector 13 is temporarily stored in the memory 14 based on the second clock. Then, the information data written based on the first clock is read out in a predetermined order having a normal arrangement relationship on the time axis. Specifically, for the duplicated information data, one of the information data is invalidated and only one of the information data is read, and for the information data to which only one is written, the information data is read. . That is, by this reading process,
The information data that has been compressed to less than 1/2
The information data string in the original state is restored while being expanded twice or more. The information data thus read out is taken out via the output terminal 18 as a reproduction output S5 and supplied to other devices.

The operation of the above-described receiving apparatus when an error occurs will be described in more detail. For example, if the transmission path deteriorates and an error occurs in the radio signal S2 in a section indicated by 31 in FIG. 3C, the error detector 13 detects an error, and
As shown in D, a high-level error occurrence signal S3 is formed. At the rising timing of the error occurrence signal S3, the switching signal S4 of the characteristic switching circuit 16 also rises to a high level as shown in FIG. 3E. For this reason, the reception characteristics of the high-frequency amplifier filter 11 are switched and adjusted to an optimal state.

When the receiving characteristic of the high-frequency amplifier filter 11 is switched to an optimum state, the radio signal S2 becomes
After a momentary disturbance as shown in FIG. 3C, the characteristics are improved and a normal signal is restored. However, since the error section of the radio signal S2 extends over two frame sections, the high level state of the error occurrence signal S3 is 2 as shown in FIG. 3D.
It is held over the frame section. Therefore, as shown in FIG. 3F, the output signal S5 from the error detector 13 invalidates a frame in which an error is detected (indicated by “1” and “2” in FIG. 3F) and outputs a normal frame in which no error is detected. Only the information data is extracted. Note that, in FIG. 3F, 'is added to the second read data of the same information data.

The signal S5 is supplied to the memory 14, and is temporarily stored in the memory 14, and thereafter, the information data is read out in a predetermined order having a normal arrangement relationship on the time axis. Therefore, as shown in FIG. 3G, the reproduced output S6 from the memory 14 is read out from one of the information data “0” and “0 ′” and is expanded by a factor of two or more.
With respect to the part missing due to the error, the information data "1 '" and "2'" are read out and expanded by a factor of two or more to restore the original information data sequence.

As a specific example of the means capable of setting the above-mentioned reception characteristic to an optimum state, in the case of radio wave transmission, a spatial diversity antenna for switching a plurality of antennas, a directivity switching of antennas, and the like are provided. is there. In the case of power line transmission, there is a phase equalizer or the like that simultaneously transmits the same information at different frequencies and corrects frequency diversity or group delay characteristic disturbance selected on the receiving side. Further, in the case of infrared transmission, there is directional diversity using a plurality of photodiodes. By using such means, the reception characteristics can be optimized.

In one embodiment of the present invention,
A description will be given of a case where a second clock that is twice or more the first clock of the information source is generated, and two pieces of information data that are continuous on the time axis are transmitted twice over two periods of the first clock. However, the second clock is
May be read out and transmitted three times on the time axis three times over two periods of the first clock, and the same information data may be read four times or more. You may make it transmit.

[0030]

According to the present invention, the same information data is read out and transmitted twice or more by a clock having a frequency twice or more as high as the clock of the information source. In this case, a normal data portion can be selected and output, and an error for a relatively long time can be compensated without increasing the circuit scale.
Further, according to the present invention, the reception characteristics are switched based on the output of the error detector and are adjusted to the optimum reception characteristics, so that the reliability in transmission is improved even in an environment where the transmission characteristics change drastically. Can be done.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a wireless transmission device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a receiving device according to an embodiment of the present invention.

FIG. 3 is a schematic diagram used for describing the operation of the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Information source, 2, 14 ... Memory, 3 ... Error detection code / synchronous pattern adder, 4, 15 ... Timing generator, 5 ... Modulator, 6 ... Carrier wave Oscillator,
11 ... high frequency amplification filter, 12 ... detector, 1
3 ... Error detector, 16 ... Characteristic switching circuit

Claims (3)

[Claims] 1. A radio transmitting apparatus for transmitting information data supplied from an information source, a timing generating means for generating a clock twice or more as fast as the information source, and storing information data from the information source. A storage unit configured to read out the stored information data based on the clock; an information addition unit that adds an error detection code, a synchronization pattern, and a frame identification code to the information data; Transmitting means for modulating the output and transmitting the information data at least twice in different time zones. 2. A receiving apparatus for reproducing information data from a received signal, a demodulating means for demodulating the received signal, a timing generating means for generating a clock from the signal obtained by the demodulating means, Storing means for storing the stored signal, and reading out the stored signal based on the clock; error detecting means for detecting an error in a frame output from the demodulating means; A reception varying means for varying a reception characteristic based on an output; and an output means for selecting and outputting an error-free frame among the demodulated frames of the same information data. apparatus. 3. A transmission / reception system for transmitting information data supplied from an information source and receiving the transmitted signal to reproduce the information data, wherein a timing of generating a clock at least twice as fast as the information source is generated. Generation means; storage means for storing information data from the information source; and reading out the stored information data based on the clock; and error detection code, synchronization pattern, and frame identification code for the information data. Information transmitting means for modulating an output of the information adding means, transmitting the information data at least twice in different time zones, and receiving and demodulating a signal transmitted by the transmitting means. Demodulation means; timing generation means for generating a clock from a signal obtained by the demodulation means; Storage means for storing a signal, and reading the stored signal based on the clock; an error detection means for detecting an error in a frame of an output of the demodulation means; and an output of the error detection means. A transmission / reception system, comprising: a characteristic variable unit for varying a reception characteristic based on the received data; and an output unit for selecting and outputting an error-free frame among the demodulated frames of the same information data.