JPH0946315A - Demodulation circuit and receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate a transmission line response by simple constitution and to obtain a detection output with less interference by providing this receiver with a transmission line response estimating part, leading out transmission line response information from a reverse discrete signal by arithmetic processing and detecting a modulation wave. SOLUTION: One of output signal is from a correlator 4 is supplied to a detection circuit 51 in a demodulator 5 and the other is supplied to the transmission line response estimation part 6 for calculating the transmission line response of each received signal by estimation. In the estimation part 6, a transmission line communication state information obtained from the output of the correlator 4 and mutual correlation characteristics information between plural discrete codes previously set in respective lines by a data setting circuit 62 are supplied to an arithmetic circuit 61 and transmission line response estimation signals are generated by arithmetic processing for suppressing interference between the codes. The estimation signals from the estimation part 6 are supplied to the circuit 51 and synchronously detected and receiving signals for a specific user station are outputted through respective discriminators 7. Since the estimation part 6 can execute more accurate transmission line response estimation by the simple constitution, an interference signal can be reduced and receiving outputs with excellent detection characteristics can be obtained from the succeeding demodulator 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a demodulation circuit and a receiver suitable for multiple access communication.

[0002]

2. Description of the Related Art In multiple access communication, one repeater can be commonly used by many stations, and therefore it is used in satellite communication, car telephones, mobile telephones and the like. When a single repeater is used by many stations in common, it is easy to receive interference between transmission lines,
To avoid this, frequency division and time division, as well as code division multiple access, that is, code division multiple access (C
DMA: Code Division Multipl
e Access) system is adopted.

In the CDMA system, a specific code is assigned to the line of each station, the transmitting side spreads the modulated wave of the same frequency by the specific code assigned to each line, and transmits the specific code. This is a method of receiving a signal by identifying a specific line in synchronization with.

In a system in which a large number of user stations use the same frequency at the same time, transmission signals from a large number of stations are superposed at one receiving station and interfere with each other to deteriorate communication quality. The deterioration of communication quality due to such interference has the property that the communication environment in the transmission line changes individually and becomes complicated in the use where the transmission / reception place of the user station moves, such as the use in car phones and mobile phones. Have.

In the demodulation circuit and the receiver used in the conventional CDMA system, the reception characteristics are deteriorated by the influence of the interference signal, so that the number of communicable stations is limited or the signal-to-interference signal ratio (CIR) is set. If is relatively large, the deterioration of communication quality is unavoidable, and it is used as it is within the allowable range. However, if the allowable limit is exceeded, it is necessary to change the distance between the stations that cause interference signals with each other, which hinders the effective use of the transmission path, and therefore improvement has been demanded.

Although various circuits have been considered for removing or suppressing the interference in communication to some extent on the receiving side, this is a practical problem because the circuit configuration becomes complicated and a large-scale computer is required.

[0007]

As described above, in a conventional receiver used for code division multiple access communication, an interference wave due to an increase in the number of user stations causes deterioration of communication quality, and demodulation for improving this is caused. Since the circuit and the receiving device require a large-scale arithmetic circuit, improvement has been demanded.

[0008]

The present invention solves the above-mentioned problems of the prior art. A demodulation circuit of the first invention introduces a modulated wave whose spectrum is spread by a code and obtains a correlation with the code. And a correlator that performs despreading processing, and a transmission line that introduces the correlator output and calculates the correlator output information of the transmission line by the calculation process of the correlator output information and the predetermined cross-correlation characteristic information of spreading code A response estimating unit and a demodulator for detecting the correlator output signal by introducing the transmission line response information from the transmission line estimating unit and deriving a detection signal of the modulated wave are characterized by being provided.

According to the present invention, the transmission line response estimation unit is provided, and the transmission line response information is derived from the despread signal by the arithmetic processing to detect the modulated wave, so that the transmission line response is estimated and the interference is obtained with a simple structure. A detection output with less signal can be obtained.

A receiving device according to a second aspect of the invention is an antenna for receiving a modulated wave which is spread spectrum with a specific code assigned to each line, and a frequency conversion of the modulated wave which is connected to the antenna and received. A high-frequency circuit, a first correlator that is connected to the high-frequency circuit, performs a despreading process by correlating the frequency-converted modulated wave with one of the specific codes, and is connected to the high-frequency circuit and frequency-converted. A second correlator that outputs the channel response information of the interference signal by performing the despreading process by taking the correlation between the modulated wave and the specific code other than one of the specific codes, and this second correlator A demodulator that is connected to the first correlator and detects the first correlator output signal after reducing the interference signal included in the first correlator output signal by the second correlator output, and this demodulator The first and second Characterized by a control unit for deriving an operation control signal connected to the correlators.

Therefore, according to the present invention, in the demodulator, the signal from each correlator is introduced to reduce the interference signal contained in the signal data of the partner station, and then the signal is detected. Can be obtained.

The receiving device according to the third aspect of the present invention similarly includes an antenna for receiving a modulated wave which is spread spectrum with a specific code assigned to each line, and a frequency conversion of the modulated wave which is connected to the antenna and received. A high-frequency circuit, a third memory circuit connected to the high-frequency circuit and holding a frequency-converted modulated wave, a subtractor connected to the third memory circuit, and a subtractor connected to the high-frequency circuit. An interference replica signal generation circuit that generates an interference replica signal of a modulated wave corresponding to at least one of the specific codes introduced from a high frequency circuit and supplies the interference replica signal to a subtractor,
A third correlator that is connected to the subtracter and performs despreading processing by correlating the modulated wave corresponding to one of the specific codes subtracted by the interference replica signal and the one of the specific codes, A demodulator connected to the third correlator for detecting an output signal from the third correlator.

That is, according to the present invention, the interference replica signal generating circuit is provided, and the interference replica signal is subtracted from the received signal, whereby the interference signal is efficiently removed with a simple structure.

Next, the receiving device according to the fourth aspect of the present invention includes an antenna for receiving a modulated wave which is spread spectrum with a specific code similarly assigned to each line, and a modulated wave which is connected to this antenna and received. A high-frequency circuit for frequency conversion, a fourth memory circuit connected to the high-frequency circuit for holding a frequency-converted modulated wave, and first and second switching circuits respectively connected in parallel to the fourth memory circuit. , A fourth correlator which is connected to the first switching circuit and performs a despreading process by correlating the introduced modulated wave with each specific code, and a despreading process connected to the fourth correlator Corresponding to the judgment circuit that judges the transmission line corresponding to the modulation wave with the largest transmission path response estimation value among the modulated waves, and the transmission line that is connected to this judgment circuit and the fourth correlator and judged by the judgment circuit You A second demodulator that detects a modulated wave, a spreading circuit that is connected to the second demodulator and that spreads the derived detection signal, and an output signal of the spreading circuit and a transmission path response estimation determined by the determination circuit A multiplication circuit that multiplies the maximum value signal, and the output signal of the multiplication circuit is subtracted from the modulation wave that has been introduced and held in advance through the second switching circuit, and the result is supplied to the fifth memory circuit and the fourth correlator. And a third switching circuit for controlling the switching so that the modulated wave held in the fifth memory circuit is switched and supplied to the fourth correlator and the detection signal is output to the output terminal. Each of the first to third switching circuits is characterized by sequentially demodulating and reducing the interference wave from the received modulated wave having a large transmission path response estimated value, and deriving a detection output having a smaller interference wave.

As described above, the receiving device according to the present invention is
Since the interference signals are sequentially subtracted and removed from the descending order of the transmission path response estimated value with a simple configuration, it is possible to obtain a high-quality detection output with less interference signals by repeating the interference signals.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a demodulation circuit and a receiver according to the present invention will be described in detail below with reference to the drawings.

Generally, in mobile communication employing CDMA, a plurality of moving user stations (X1, X2, ... XN) are connected to a base station (Y1 or Y2) as shown in the schematic communication system in FIG. Communication lines (h1, h1 ′, h2, h2) unique to each of them via the base station (Y1 or Y2).
, ..., hN, hN ′) are used for code division multiplex communication.

The demodulation circuit and the receiving device of the present invention are applied to both the receiving side of the base station and the user station. In the following, the case of being adopted in the base station (Y1, Y2) side is taken as an example. explain. FIG. 2 is a block diagram for explaining an embodiment of the demodulation circuit and the receiver according to the present invention.
That is, a modulated wave spectrum-spread with a specific code transmitted from the transmission side (user station side), that is, direct spread-spread spectrum (DS-SS: Direct Spread-).
The Spectrum Spread signal is transmitted to the antenna 1a.
Or it is received in 1b.

Although the two antennas 1a and 1b are used for diversity, the case where the received signals are switched or combined by the high frequency circuit 2 is shown.
Individuals are fine.

The modulated wave received by the antenna 1a or the like is supplied to the high frequency circuit 2 and converted into an intermediate frequency band signal (or base band) by frequency conversion. The modulated wave converted into the intermediate frequency band signal passes through the A / D converter 3 and the correlator 4
Is supplied to. The correlator 4 is composed of a number of matched filters corresponding to the spread codes respectively assigned to the plurality of communication lines. Of course, the number of matched filters may be limited to only the number of multiplexed communication lines among the number of communication lines transmitted and received by the one base station, and can be appropriately selected. A configuration including a plurality of matched filters is referred to as a matched filter bank. However, since the correlator 4 needs to be configured corresponding to a large number of transmission lines, it is usually formed by a matched filter bank.

Therefore, the correlator 4 composed of a plurality of matched filters inverses the modulated wave from the A / D converter 3, which is spectrum-spread with a specific code corresponding to the transmission line, that is, the DS-SS signal. Perform diffusion processing.

Now, in the configuration of the correlator 4, a matched filter for performing despreading processing by correlating with one of the specific codes is a first correlator 41, and another specific code other than the one of the specific codes. The matched filter that performs the despreading processing by obtaining the correlation with and outputs the transmission path response information and the data portion information of the interference signal will be referred to as a second correlator 42 and described below.

The outputs of the first and second correlators 41 and 42 include the original cross-correlation between spreading codes, a reception time difference due to a difference in transmission line length, or a band formed on the transmission side. Interference components caused by the influence of the limiting filter are mutually included.

One of the output signals of the correlator 4 is supplied to the detection circuit 51 of the demodulator 5.

The other of the output signals of the correlator 4 is the transmission path response estimation unit 6 for estimating and calculating the transmission path response of each received signal.
Is supplied to. The transmission path response estimation unit 6 is composed of an arithmetic circuit 61 and a data setting circuit 62. In the data setting circuit 62, known cross-correlation characteristic data between respective codes required for calculating the transmission path response is registered in advance. There is. Therefore, correlator 4
The communication state information of the transmission line obtained from the output and the cross-correlation characteristic information between the spreading codes preset for each line of the data setting circuit 62 are supplied to the arithmetic circuit 61, and the arithmetic for suppressing the interference between the codes is performed. The transmission path response estimation signal is generated by the processing.

The transmission line response estimation signal from the transmission line response estimation unit 6 is supplied to the detection circuit 51 of the demodulator 5, where it is synchronously detected, and the reception signal of the specific user station is output via the decision unit 7. It

The outputs of the correlator 4 and the demodulator 5 are also supplied to the control unit 8, where the timing information of the code, the frame configuration information of the code (switching information between the known signal and the data to be demodulated), and the reception. Signal level, transmission line information, etc. are analyzed. Particularly, in the receiver in DS-SS, the code synchronization circuit 81 in the control unit 8 synchronizes the sampling signal S to the A / D converter 3 as well as the code to the correlator 4 and the channel response estimation unit 6. Clock signal (CL
K) and the code timing signal F to the demodulator 5 are generated and supplied respectively.

In FIG. 1, by the way, from the base station (Y1) side, each of N user stations (X1, X2, which are mobile terminals).
.. XN) side, since the transmission paths such as the communication distance and the direction of each user station terminal are different, the transmission signals from each user station are received under the influence of different transmission path responses.

Therefore, the propagation path response constant hn (n = 1 to N) in each transmission path is represented by one propagation path response matrix h, which is expressed by the following equation (1).

H = (h ₁ , h ₂ , ..., h _N ) ^T (1) where T means transposition.

On the other hand, if outputs of the number of user stations (N) are obtained from the correlator 4 and this correlator 4 output is On (n = 1 to N), it is similarly expressed by the following equation (2). It

[0032] _{O = (O 1, O 2} , ..., O N) The T (2), the frame structure of the signal received by the antenna 1a, for example, as shown in FIG. 3, the known signal k and the data d
And a configuration in which a signal portion having a time length T is continuous at a repetition period T, or a signal having a time length T / 2 is transmitted / received within a repetition period T by a known signal k and data d as shown in FIG. There is a configuration in which they are alternately performed and are continuous. FIG. 4 shows a plurality of received signals (a), (b), ... (f) having the same frame structure.
(G) shows how the received signals are asynchronously received with a time delay difference or the like due to different transmission paths.

In the frame structure of the received signal, the known signal k is registered in advance on the base station side.
At the base station side, not only the known signal k but also various characteristics such as the spreading code at the user station side, the code timing of the code, and the band limiting filter are obtained as known information in advance. However, on the side of the base station, if it is possible to know the waveform of the burst signal such as ramp-up or ramp-down, it can be used together with or as an alternative to the known signal k.

Therefore, the base station can obtain the cross-correlation matrix C of the multiple signals represented by the following equation (3) from the information that can be known in advance.

[0035]

[Equation 1] Here, c _ij is the signal of the i-th user station (known signal is spread by the code i, filtered, and further delayed in accordance with the code timing information of the i-th code) and the j-th signal. It represents the cross-correlation value with the signal of the user station.

Since the output O of the correlator 4 includes the channel response matrix h of each user station in an amount according to the cross-correlation matrix C, these relationships are expressed by the following equation (4). It

O = Ch (4) Therefore, from this equation (4), the channel response matrix h for each user station is expressed by the following equation (5).

H = C ^-1 O (5) Here, when there is no change in the received signal from each user station (spread code pattern and time delay difference), the cross-correlation matrix C does not change either. Therefore, the inverse matrix C ^-1 can be calculated every time, but all combinations may be prepared in advance as a table or may be recalculated only when there is a change in the received signal.

Further, when there is a time delay difference between the user stations and there is a possibility that a data component may enter the known signal k in the case of asynchronous reception, at this time, the cross-correlation matrix C including the data component is also included. You can also ask.

As described above, the transmission line response estimation unit 6
Since a more accurate transmission path response estimation is performed with a simple structure, the next demodulator 5 can obtain a reception output with few interference signals and excellent detection characteristics.

FIG. 5 is a block diagram of essential parts for explaining the second embodiment according to the present invention. The difference from the first embodiment shown in FIG. In addition to the arithmetic circuit 61 and the data setting circuit 62, the arithmetic circuit 6
A first memory circuit 63 for temporarily holding the output signal of 1 for a time length of 1/2 of the repetition cycle T or a time length of the repetition cycle T, the signal held in the first memory circuit 63, and the arithmetic circuit A first arithmetic circuit for performing interpolation calculation with the signal output from 61 (interpolation interpolation operation when the time length is 1/2 the repetition cycle T, and extrapolation interpolation operation when the time length is the repetition cycle T). 64 is added, and a second memory circuit 9 for delay time adjustment is newly added between the correlator 4 and the demodulator 5. Of course, the first and second memories 63 and 9 may be composed of delay lines.

The first arithmetic circuit 64 of the transmission line response estimation unit 6
In the demodulator 5, the output is multiplied by the output signal of the correlator 4 whose delay time has been adjusted by the second memory circuit 9, and the decision unit 7
From this, it is possible to obtain a good reception detection output.

Next, FIGS. 6 (a) and 6 (b) are block diagrams of a main part for explaining a third embodiment of the receiving apparatus according to the present invention, in which an antenna 1a for receiving a modulated wave and this antenna 1a are provided. A high-frequency circuit 2 for converting the frequency of the connected and received modulated wave, a third memory circuit 10 connected to the high-frequency circuit 2 for holding the frequency-converted modulated wave, and connected to the third memory circuit 10. , And the interference replica signal generation circuits 121, 122, ... 12L connected to the high-frequency circuit and generating interference replica signals of modulated waves corresponding to specific codes respectively and supplying the interference replica signals to the subtractor 11.
A third correlator 43 connected to the subtractor 11 and performing a despreading process by correlating the modulated wave corresponding to one of the specific codes subtracted by the interference replica signal with one of the specific codes. The output of this correlator 43 is taken out as a detection output via the demodulator 5 and the determiner 7.

The interference replica signal generation circuit 12 is prepared for all or some of the user stations except the desired signal wave. Therefore, the subtractor 11 removes interference signals from other user station reception signals other than the target user station signal, and the remaining signals are despread by the third correlator 43. Since the third correlator 43 is a matched filter corresponding to one specific user station (communication partner station) in the matched filter bank provided corresponding to a plurality of user stations, it is possible to reduce the interference signal. The received signal of the user station is detected by the demodulator 5 and then output through the determiner 7.

A detailed circuit of each of the interference replica signal generating circuits 121, 122, ..., 12L constituting FIG. 6A is shown in FIG.
A description will be given with reference to (b). That is, the signal sampled by the A / D converter 3 is first supplied to the correlator 4 composed of a matched filter bank, and the output signal of this correlator 4 is supplied to the demodulator 5 and the transmission line response estimation unit 6 for transmission. The path response estimation unit 6 receives the timing signal (CLK) from the code synchronization circuit 81 in the control unit 8 and receives the cross-correlation matrix C.
Is calculated. The detection signal of the demodulator 5 is the first multiplier 131.
To a second multiplier 132, which is re-spread with the spreading code generated by the spreading sequence generator 14 and is supplied to the second multiplier 132 through the low-pass filter 15 and the estimated transmission line response value from the transmission line response estimation unit 6. By being multiplied, an interference signal replica is generated and supplied to the subtractor 11. The spreading sequence generator 14 generates an adjusted spreading code based on the code timing information from the code synchronization unit 81.

In addition, each interference replica signal generator 121,
In the configuration of 122, ..., 12L, the matched filter bank, the code synchronization circuit 81, and the transmission path response estimation unit 6 that form the correlator 4 are common to each user station, and are different interference replica signal generation circuits from each other. Can be shared with. In addition, the plurality of interference replica generation circuits 121 and 12
The number of 2, ..., 12L and the combination thereof can be arbitrarily selected, and of course, all user stations may be configured.

Next, FIG. 7 is a block diagram showing a fourth embodiment according to the present invention. Similarly, the modulated wave connected to the antenna 1a and received is frequency-converted by the high frequency circuit 2 and then A / D. It is supplied to the fourth memory circuit 16 via the converter 3. First to third switching circuits 17, 18, and 19 are connected to the fourth memory circuit 16, and the signal supplied to the first switching circuit 17 passes through the first subtraction circuit 20 to the first subtraction circuit 20. It is supplied to and stored in the memory circuit 21. On the other hand, the received modulated wave supplied to the second switching circuit 18 is subjected to despreading processing by correlating it with a specific code by the fourth correlator 44. The modulated wave despread by the fourth correlator 44 is passed through the transmission response estimation section 6 and the determination circuit 82 of the control section 8 determines the transmission line corresponding to the modulated wave having the largest absolute value of the transmission path response value. To be done. The output signal of the decision circuit 82 is supplied to the second demodulator 52, and in the decision circuit 82, the modulated wave corresponding to the decided transmission line among the despread processing modulated waves introduced from the fourth correlator 44. To detect.

The detection output is re-spread by the spreading circuit 22,
Further, the estimated transmission response value from the transmission line response estimation unit 6 is multiplied by the multiplication circuit 23, and then is supplied to the first subtraction circuit 20 via the first low pass filter 24. In this first subtraction circuit 20, the received modulated wave held in advance in the fifth memory circuit 21 is introduced through the first switching circuit 17 and the signal from the first low pass filter 24 is subtracted, The subtraction signal is supplied to the fifth memory circuit 21, updated and held, and also supplied to the fourth correlator 44 via the second switching circuit 18. The output signal of the first subtraction circuit 20 is despread by the fourth correlator 44, and thereafter, the transmission path response is estimated, the maximum absolute value of the user station is determined, the demodulation is performed again by the same path as the previous signal. The interference wave of the signal having the second largest absolute value of the transmission path response is removed by the first subtraction circuit 20 through the diffusion or the like. In this way, the operation is repeated until the demodulation detection of the signal with the smallest transmission path response is completed at the end.
Noise can be further reduced. When the interference signal becomes the minimum, the third switch circuit 19 is activated by the control timing signal from the control unit 8, and the minimum interference wave modulated wave held in the fifth memory circuit 21 becomes the second switch. It is supplied to the fourth correlator 44 via the circuit 18 and can be derived from the output terminal 25 via the second demodulator 52.

As described above, the demodulation circuit and the receiver according to the present invention constantly observe the transmission path regardless of the presence or absence of the interference signal, and estimate the transmission path response at the reception time based on the obtained transmission path information. The value is calculated accurately, the interference signal is reduced from the received signal, and the detection output is obtained.
Therefore, the communication quality can be improved with a simple circuit configuration even under the adverse interference between other stations, which is a great effect in practical use.

[0050]

INDUSTRIAL APPLICABILITY As described above, the demodulation circuit and the receiving device according to the present invention have a simple circuit configuration and can effectively remove the interference wave signal, and are applied to a receiver used for code division multiple access communication. The advantage is that the number of stations can be easily accommodated and communication quality can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a communication system to which a receiving device according to the present invention is applied.

FIG. 2 is a block diagram showing a first embodiment of a receiving device according to the present invention.

FIG. 3 is a frame configuration diagram of a signal received by the receiving device shown in FIG.

FIG. 4 is another frame configuration diagram of a signal received by the receiving device shown in FIG.

FIG. 5 is a principal block diagram showing a second embodiment of a receiving device according to the present invention.

FIG. 6 is a principal block diagram showing a third embodiment of a receiving device according to the present invention.

FIG. 7 is a principal block diagram showing a fourth embodiment of a receiving device according to the present invention.

[Explanation of symbols]

1a, 1b Antenna 2 High frequency circuit 4 Correlator 41-44 1st-4th correlator 5 Demodulator 52 Second demodulator 6 Transmission line response estimation part 7 Judgment machine 8 Control part 81 Synch code circuit 82 Judgment circuit 9 Second memory circuit 10 Third memory circuit 11 Subtractors 121, 122, ..., 12L Interference replica signal generation circuit 13 Multiplier 16 Fourth memory circuit 17-19 Switching circuit 20 Subtraction circuit 21 Fifth memory circuit 22 Spreading circuit 23 Multiplier circuit

Claims (7)

[Claims] 1. A correlator that introduces a modulated wave spectrum-spread by a code and performs a despreading process by correlating with the code, and a correlator output that introduces the correlator output and is predetermined with the correlator output information. A transmission path response estimation unit that calculates transmission path response information of a transmission line by calculation processing with cross-correlation characteristic information of a spreading code, and the correlator output signal by introducing the transmission path response information from this transmission path response estimation unit. And a demodulator for detecting the demodulated signal of the modulated wave. 2. An antenna for receiving a modulated wave spectrum-spread with a specific code assigned to each line, a high-frequency circuit connected to this antenna for frequency-converting the received modulated wave, and this high-frequency circuit. A first correlator that is connected to the first frequency correlator and performs a despreading process by correlating the frequency-converted modulated wave and one of the specific codes, and the frequency-converted modulated wave connected to the high-frequency circuit and the specific code. The second correlator that outputs the channel response information of the interference signal by performing the despreading processing by taking the correlation with the specific code other than one of the above, and the second correlator and the first correlator A demodulator that is connected and detects the first correlator output signal after reducing the interference signal included in the first correlator output signal by the second correlator output, and this demodulator and each of the first and second correlators Connected to a correlator to control operation And a control unit for deriving a signal. 3. The communication state information of the transmission line, which is connected between the second correlator and the demodulator, and which is obtained from the output of the second correlator, and the spreading code preset for each line. 7. A transmission line response estimation unit for supplying the demodulator with transmission line response information generated by the correlation characteristic information and the demodulator, wherein the cross-correlation characteristic information is derived from a known signal of the transmission signal. 2. The receiving device according to 2. 4. The transmission path response estimation unit includes a memory circuit that holds the transmission path response information, and the transmission path response information stored in advance in the memory circuit and the transmission path response information after that are stored in the memory circuit. The receiving apparatus according to claim 3, wherein the transmission path response estimated value information obtained by interpolation or extrapolation is supplied to the demodulator. 5. A second memory circuit connected between each of the first and second correlators and the demodulator, wherein the second memory circuit output signal is after the interference signal is reduced in the demodulator. The receiving apparatus according to claim 4, wherein the reception is performed using the transmission line response estimation value information supplied from the transmission line response estimation unit. 6. An antenna for receiving a modulated wave spectrum-spread with a specific code assigned to each line, a high-frequency circuit connected to this antenna for frequency-converting the received modulated wave, and this high-frequency circuit. Connected to the third memory circuit for holding the frequency-converted modulated wave, a subtractor connected to the third memory circuit, and a subtractor connected to the high-frequency circuit and introduced from the high-frequency circuit. An interference replica signal generation circuit that generates an interference replica signal of a modulated wave corresponding to at least one of the specific codes and supplies the interference replica signal to a subtractor, and the specific signal subtracted by the interference replica signal that is connected to the subtractor. A third correlator that performs despreading processing by correlating the modulated wave corresponding to one of the codes and one of the specific codes, and a third correlator connected to the third correlator And a demodulator for detecting an output signal from the correlator. 7. An antenna for receiving a modulated wave spectrum-spread with a specific code assigned to each line, a high-frequency circuit connected to this antenna for frequency-converting the received modulated wave, and this high-frequency circuit. Connected to the fourth memory circuit for holding the frequency-converted modulated wave, first and second switching circuits respectively connected in parallel to the fourth memory circuit, and connected to the first switching circuit The fourth correlator that performs the despreading process by correlating the introduced modulated wave with each specific code, and the transmission path response of the despread processed modulated wave that is connected to the fourth correlator A determination circuit for determining the transmission line corresponding to the modulation wave having the largest estimated value, and a second detection circuit connected to this determination circuit and the fourth correlator for detecting the modulation wave corresponding to the transmission line determined by the determination circuit Demodulation of And a spreading circuit connected to the second demodulator for spreading the derived detection signal, and a multiplication circuit for multiplying the spreading circuit output signal by the transmission path response estimated maximum value signal determined by the determination circuit. A subtraction circuit for subtracting the output signal of the multiplication circuit from the modulated wave introduced and held in advance via the second switching circuit and supplying the subtracted output signal to the fifth memory circuit and the fourth correlator; And a third switching circuit for switching and supplying the modulated wave held in the memory circuit to the fourth correlator and for deriving a detection signal to the output terminal. A receiving device characterized in that a circuit sequentially demodulates a received modulated wave having a large transmission path response estimated value and reduces an interference wave, and derives a detection output having a smaller interference wave.