JP3182447B2 - Correlation detection type detection device and correlation type signal detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correlation detection type detection device for obtaining a required detection signal by correlating using a promised waveform at the time of transmission, and to detect a required signal from a received signal by a similar configuration. The present invention relates to a correlation type signal detection device.

[0002]

2. Description of the Related Art There are a reflection type detection device and a transmission type detection device in this type of detection device, and the reflection type detection device includes a land condition, a ship navigation condition, a relative distance condition and the like by a reflected wave of an electromagnetic wave. Underwater objects, airborne objects, and relatives are reflected by sound waves or ultrasonic waves, such as radars for ships that detect objects, underground surveys that detect conditions of buried objects under the ground surface, changes in strata, and relative distances. There are fish finder and sonar etc. that detect the distance situation, etc., and as the transmission type detection device, the buried object situation and the stratum change situation etc. in the underground route between the required points by the transmitted wave (also called the passing wave) of the electromagnetic wave There are transmission / reception opposed detection radars and borehole radars that detect by transmitted waves, and transmission / reception opposed detection sonars that detect underwater and airborne objects by sound waves and ultrasonic waves.

In this type of detection device, a device provided with a correlation function for increasing the detection capability, that is, as a correlation detection type detection device, a plurality of reception signals obtained in each detection cycle are superimposed. In this case, a configuration that takes a correlation is used.

[0004] This configuration is based on the signals R1, R2, R3 shown in FIG.
By superimposing a plurality of reception signals of each detection period T obtained by transmitting a single pulse transmission signal X1 and performing a logical sum or an average as shown in FIG. In this configuration, the received signals S1 and S2 that are commonly present at the same phase point of each detection cycle T are detected as detection signals.

[0005] In addition, as a device provided with a correlation function, for example, a communication signal transmitted from a communication device or a monitoring device, or an information signal in which a monitoring signal in a facility is multiplexed is repeated at a required period. A correlation signal detection device configured to obtain a required detection signal by correlating the signal with a correlation signal having a promised waveform at each time of the cycle, the signal being a signal including a waveform signal. Can be considered.

In order to make such a correlation effective, the transmission waveform may be a stepped amplitude form in which a specific promise is made for amplitude change, frequency change, phase change, number of pulses, pulse interval, etc., an equal waveform repetition form, or the like. In the former, the step-shaped amplitude type, in which the amplitude is changed stepwise, the latter, in which the waveform is repetitive, the half-sinusoidal pulse or the rectangular pulse is applied in the positive direction. 7 or repeated in a predetermined number by arranging in both the positive and negative directions. The simplest waveform is a single one as shown in FIG.
Cycle (referred to as monocycle in the present invention),
As shown in FIG. 7B, there is a unipolar pulse corresponding to a single half cycle.

The reason why the correlation function is provided in the detection device is mainly that a detection signal having a good S / N is obtained by removing interference interference and environmental noise from a weak reception signal having a low S / N, and obtaining a detection signal having a good S / N. Even if the power peak value is small, the detection distance can be increased. Similarly, even if the transmission signal has a small power peak value, the function using the pulse compression technique is a function that can increase the detection distance. There is a configuration in which pulse compression is performed using waveforms such as stepped frequency modulation format, linear frequency modulation format, code phase modulation format, and code carrier modulation format. Technology (2) ".

Here, the step frequency modulation type is
As shown in the waveform (a) of FIG. 6, the frequency is changed as f1, f2, f3, f4, f5 for each small unit time Ta.
As shown in the waveform (a) of FIG.

In the case of the code phase modulation type, as shown in a waveform (c) of FIG. 6, a signal of each cycle having a constant cycle Tb is defined as a pulse signal of one unit. A code whose phase starts from the 0 ° position is set to “+” and a signal whose phase starts from the 180 ° position is set to “−”, and the code of the code carrier modulation type is the code shown in FIG. ), The frequencies f1 to f5 of the signal in the stepped frequency modulation format are changed to carrier signals of the same frequency, and the carrier wave at each unit time Ta is converted into the carrier signal of FIG.
Each unit pulse is encoded in the same manner as the pulse of each unit in the code phase modulation type waveform (c).

It is needless to say that the waveforms in each of these formats can be used as promised waveforms for the above-mentioned correlation function. In the present invention, the promised waveform is
It indicates a waveform in each of these formats.

[0011]

In the above-described correlation configuration in which a plurality of periods are superimposed and a logical sum or an average is obtained, as shown in FIG. However, if the signal exists at the same location, that is, at the same phase point, there is a disadvantage that the signal is detected regardless of the noise signal or the interference signal.

For this reason, there is a problem that provision of a simple and inexpensive configuration free of such inconveniences is desired.

[0013]

According to the present invention, there is provided a reflected wave obtained by transmitting a transmission signal having a bundled waveform having a time length shorter than the period repeated at a required period as described above. or correlation-detecting detection equipment to obtain the desired detection signal correlated with the received signal promise waveform of the transmitted waves, were or, Shin with short duration promise waveform than the cycle repeats with a period of a Kaname Tokoro < in correlated signal detection device to obtain a desired detection signal correlated by promises waveform a received signal comprising br /> No., before
A fixed period for transmitting the transmission signal with a constant period
A period transmitting means, a variable delay correlation signal means for obtaining a delayed commitment waveform signals are sequentially delayed by a small amount time commitments waveform each time the cycle as a correlation signal, the received signal as an object to be correlation signal, the period Detection signal or detection signal based on the multiplication signal obtained by multiplying the
The above-mentioned problem can be solved by providing a multiplication means for obtaining a signal.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment will be described below with reference to FIG. The embodiment shown in FIG. 1 is an underground exploration radar for exploring the underground from the air, in which the waveform of one cycle as shown in FIG. The configuration is such that a correlation is obtained, and the signals of each section are shown in FIG.

The fixed period circuit 1 is a time generation circuit, for example, a circuit for counting a predetermined amount of unit time pulses to obtain a period signal, and transmits a pulse signal having a fixed period T as a fixed period signal 1A. Circuit 2 and the variable delay circuit 12.

The transmitting circuit 2 supplies the transmitting antenna 2 with a transmitting signal 2A in which a monocycle signal generated by the transmitting waveform generating circuit 21 using the fixed period signal 1A as a trigger signal is converted into a required power by a power amplifying circuit 22. That is, the time length TP
This monocycle waveform repeats at the required cycle
The promised waveform has a shorter time length than the
A transmission signal 2A having a waveform is provided to the antenna 3.

The transmitting antenna 3 is a dipole antenna,
For example, it is a fan-shaped dipole antenna, which is mounted on a research aircraft or the like, and transmits a transmission signal 2A to a transmission electromagnetic wave 4.
Then, waves are transmitted from the air to the underground 6 through the ground surface 5 and the reflected electromagnetic waves 8 from the underground buried objects 7A, 7B, 7C are received by the receiving antenna 9. The reception antenna 9 is, for example, a fan-shaped dipole antenna similar to the transmission antenna, and supplies a reception signal 9 </ b> A based on the reflected electromagnetic wave 8 to the amplification circuit 10.

The amplifying circuit 10 is a high-frequency amplifying circuit. The receiving signal 9A has a required amplitude value, and the receiving signal 10A based on the signal as shown in FIG. Give as multiplication input. Received signal 10
Signals 10a, 10b, and 10c in A are reception signals obtained corresponding to reflected electromagnetic waves from underground objects 7A, 7B, and 7C, respectively.

The variable delay circuit 12 is a circuit that generates a delay pulse with a variable time amount obtained by adding a unit amount of delay time every time an input signal is supplied. For example, a variable count circuit and a clock circuit are combined. The pulse generation circuit stores a count value obtained by counting the fixed period signal 1A, and when the count value reaches a predetermined count value CM, resets the count and repeats counting again. A time length obtained by accumulating a clock having a unit delay time Δt with a time length obtained by reducing the time length TP of the signal 2A to 1 / m, for example, a time length reduced to 1/10, for each fixed period signal 1A, that is, Δt × A pulse signal delayed from the fixed period signal 1A with n as the delay amount TD is given to the correlation signal circuit 13 as a delay signal 12A.

Then, an initial value and a final value of the value of n are set so that the delay amount TD corresponds to a range to be detected within the fixed period T, and the value is reset to the initial value and returned to the initial value. The counting is repeated as described above.

The correlation signal circuit 13 is the same pulse generation circuit as the transmission circuit 2, and uses the delay signal 12A as a trigger signal and a signal having the same waveform as a signal having a promised waveform such as the correlation signal 13A, that is, a fixed period. Delay amount TD from signal 1A
A monocycle signal at a point in time delayed is generated and given as a multiplication input on the other side of the multiplication circuit 11. Therefore, when viewed from the phase of the fixed cycle T, the correlation signal 13A is shifted by the unit delay time Δt for each fixed cycle.

The multiplying circuit 11 is an analog multiplying circuit, for example, a multiplying circuit using a double balance mixer (DBM) (also called a double balance type multiplying circuit).
A multiplication obtained by multiplying the amplitude value of the multiplication input on one side and the amplitude value of the multiplication input on the other side, that is, the analog value of the amplitude value of the received signal 10A and the amplitude value of the correlation signal 13A. The integration circuit 14 uses the signal of the amplitude value as a multiplication signal 11A.
Give to.

The integrating circuit 14 is a time constant type integrating circuit, and has a time constant larger than the time length TP of the correlation signal 13A (this time length is the same as the time length of the transmission signal 2A). The integration circuit is for obtaining an amplitude value corresponding to a value obtained by integrating the multiplication amplitude values sequentially obtained during the multiplication in the multiplication circuit.

The sample holding circuit 15 is an analog type sample holding circuit, which samples the integrated amplitude value of the integrated signal 14A in each fixed cycle, for example, at the end of the time length TP of the correlation signal 13A. By holding the analog value held by sampling until the next sampling time, a signal such as the detection signal 15A in FIG.

Therefore, while the detection signal 15A is changed by the amplitude of the integral value of the signal multiplied for each correlation signal 13A in each fixed period T, the fixed period T becomes n
When the number of times has elapsed, the signal is a signal obtained by multiplying and correlating the signal portion of the received signal 10A within a required range defined by the count value n with the correlation signal 13A as a correlated signal, but has a fixed period in time. The signal is a signal that has been expanded for a time length n times as long.

If the selection of the predetermined range based on the count value n is set so as to cover the entire fixed period T, the fixed period T
Is divided by the unit delay time Δt, and the detection is repeated a number of times k, the received signal 10A has a waveform in which all the correlations have been detected, and the time length T × k during this time is compressed to 1 / k for viewing. Thus, a signal like the detection signal 15A (shortening rate 1 / k) in FIG. 2 is output as the detection signal 15A. When the promised waveform is a waveform that can be applied to pulse compression, the signal obtained as the detection signal 15A appears as a type of pulse-compressed signal.

The display circuit 16 displays the detection signal 15A as a detection image. For example, the detection signal 15A is sequentially stored in a memory for one display screen of a display by raster scanning, and the stored contents are stored. This is a circuit for displaying in the form of a B scope while reading out in synchronization with the raster scanning. The detection signal 15A in the fixed cycle T × k is used as a luminance modulation signal in the main scanning, and the detection signal 15A is sequentially shifted in the sub-scanning direction for each detection signal 15A Is displayed.

In the case of a device having the above-described configuration based on the transmission / reception opposing detection, for example, a detection device that performs an underground search using a transmitted wave as shown in FIG. The correlation signal 13A based on the promised waveform obtained by the variable delay circuit 12 and the correlation signal circuit 13 provided in any of the transmission-side circuit unit 50, the reception-side circuit unit 60, and the control / display circuit unit 70, Receiving side circuit unit 60
Alternatively, the multiplication circuit 1 provided in the control / display circuit unit 70
1, a target detection signal can be obtained by performing the same correlation detection processing as that of the correlation detection type detection device in FIG. 1 described above.

Further, in the case of the above-mentioned correlation type signal detection apparatus, a reception signal to be subjected to correlation detection, that is, a correlated signal is supplied to the multiplication circuit 11 instead of the reception signal 10A, and the above-mentioned variable delay is provided. Circuit 12 and correlation signal circuit 1
3, a correlation signal having a desired promised waveform is formed, and the correlation signal is supplied to the multiplication circuit 11 in place of the correlation signal 13A. In this case, a target detection signal is obtained by performing a correlation detection process similar to the correlation detection process in.

As described above, the correlation detection processing according to the configuration of the first embodiment shown in FIG. 1 employs a configuration in which the period of a received signal to be a correlated signal is fixed and the period of the correlation signal is variably delayed. You can see.

Next, as a second embodiment, a configuration in which the period of the correlation signal is fixed and the period of the received signal as the correlated signal is variably delayed will be described with reference to FIGS. In FIGS. 3 and 4, functional parts and signal waveforms denoted by the same reference numerals as those in FIGS. 1 and 2 indicate the same functional parts and signal waveforms as those described in FIGS. 1 and 2. It is.

In the case of the second embodiment, the variable delay circuit 12
The initial value of the delay amount TD due to Δt × n is set to the maximum value of the delay amount Δt × m, and for each fixed period T, Δt ×
(M-1), Δt × (m-2), Δt × (m-3)
As described above, the delay amount TD is gradually reduced, so that the temporal relative relationship between the received signal 10A and the correlation signal 13A in the configuration of FIG.

It is needless to say that the same correlation detection configuration as that of the second embodiment can be applied to the above-described configuration based on the opposing transmission / reception detection or the above-described correlation type signal detection device.

In the case of the second embodiment, the variable delay circuit 12 has a configuration similar to that of FIG. 1 except that the delay amount TD due to Δt × n is changed to Δt × 1, Δt × 2, t × 3 ...
When a signal having a configuration of increasing gradually as shown in FIG. 1 is used, the detected signal 15A is inverted in time series because the temporal relationship between the received signal 10A as the correlated signal and the correlation signal 13A appears in reverse. It will appear as an arrayed signal. Therefore, it is necessary to reverse the raster scanning in the display circuit 16 to make it into a regular time series, or to provide a means for changing the direction in which the detection distance of the display image is read in the opposite direction to that in FIG. There is.

In the case where the reversely arranged signals are obtained, the time series is similarly reversed in the case of the above-described configuration based on the transmission / reception opposite detection or the case of the above-mentioned correlation type signal detection device. It is needless to say that the present invention can be applied by providing a means for changing the direction.

[Modification] The present invention can be modified as follows.

(1) Waveforms in which promised waveforms are specified with respect to amplitude change, frequency change, phase change, pulse number, pulse interval, etc. described in the section of the prior art, for example, a stepped amplitude format, etc. A configuration using a waveform such as a waveform repetition format, or a waveform such as a stepped frequency modulation format, a linear frequency modulation format, a code phase modulation format, or a code carrier modulation format is used.

(2) A pulse wave obtained by modulating a signal of the promised waveform into a single high-frequency rectangular wave used in a general radar or fish finder, ie, the f1 portion of the waveform in FIG. Only the waveform is configured.

(3) The initial value of the delay amount TD of the variable delay circuit 12 is calculated by adding the fixed period T to the initial value, that is, T + Δt × n in the first embodiment and T + Δt × n in the second embodiment. Is T + △
It is configured to start from t × m. In order to add this addition amount, the delay amount of the variable delay circuit 12 is added to the second signal of the fixed period signal 1A obtained from the fixed period circuit 1.

(4) The amount of addition in (3) is set to N × T, which is a plurality of N times the fixed period T. In the case of the first embodiment, N × T + △ t × n, and in the second embodiment N × T +
It is configured to start from Δt × m. In this case, the fixed period signal 1A obtained from the fixed period circuit 1
The configuration is such that the delay amount of the variable delay circuit 12 is added to the third and subsequent signals.

(5) At the start of the delay amount TD of the variable delay circuit 12, a so-called detection range is shifted by adding an arbitrary fixed delay amount equal to or less than the fixed period T to the initial value of the delay amount. In addition, the configuration is such that the correlation detection processing is performed from the time corresponding to the target detection target, for example, the underground buried object 7B, and the detection signal 15A for the underground buried objects 7B and 7C is obtained.

(6) The variable delay circuit 12 is connected to a coaxial cable
A plurality of delay amounts are configured by a piezoelectric conversion element, a distributed constant circuit, or the like, and the respective delay amounts are switched to obtain a variable delay amount.

(7) The promised waveform of the correlation signal 13A is deformed while the promised waveform of the transmission signal 2A itself passes through the path of the transmission antenna 3, the transmission electromagnetic wave 4, the underground, the reflected electromagnetic wave 8, and the reception antenna 9. The correlation signal circuit 13 is configured so as to have a waveform close to a model to be obtained, or a circuit corresponding to a waveform close to the model, for example, a resonance circuit having a low Q is provided between the correlation signal circuit 13 and the multiplication circuit 11. And a phase shift circuit combination.

(8) The integration circuit 14 is an operation type integration circuit, and the sampling of the sample holding circuit 15 is performed at the time of the fixed period signal 1A. In this case, it is needless to say that the operation needs to be reset after sampling.

(9) In the configuration of the above (8), the digital value obtained by A / D conversion of the amplitude value obtained at each sampling time is stored in a storage circuit such as a memory or a shift register for addressing or shifting at each sampling time. Are stored in the following order, and the stored content is obtained based on a digital value read out with a clock of a predetermined constant speed, so that a waveform distortion of the detection signal 15A due to a shift at the sampling time can be obtained. Be able to fix it. When the detection signal or the detection signal is obtained in the reverse time series, the reading of the stored contents is performed in the reverse order to obtain a signal in a normal time series.

(10) The detection signal 15A is obtained by eliminating the integration circuit 14 and filtering the multiplication signal 11A by a low-pass filtering circuit. In this case, it is desirable to constitute a filtering circuit that passes a frequency corresponding to the fixed period T, that is, a frequency of about (1 / T) Hz or less.

(11) The amount of the small amount of time Δt is configured in another analog form, for example, the time to the clip level point of the rising or falling ramp is made by changing the unit clip level.

(12) Form of promised waveform and small amount of time
The quantity of t, or either, is constituted by a signal in digital form, for example a serial pulse signal or a parallel pulse representing a binary value.

(13) Form of Promised Waveform and Small Time △
An amount of t or any one of them is converted into an analog signal and converted into a digital signal to perform correlation.

(14) Form of Promised Waveform and Small Time △
The amount of t or any one of them is converted into a signal in a digital form and converted into a signal in an analog form to perform correlation.

(15) Received signal 10A / correlation signal 12A
Is digitized by A / D conversion, and the processing of the fixed period circuit 1, the multiplication circuit 11, the integration circuit 14, the sample holding circuit 15 and the like is processed by a digital computer, for example, a microcomputer.

(16) An adjustment circuit for variably adjusting the amplitude of both or one of the reception signal 10A and the correlation signal 13A input to the multiplication circuit 11 to ensure the multiplication function, for example, , A variable attenuation circuit is provided.

(17) When the frequency of the transmission signal 2A, that is, the frequency of the promised signal is low, the multiplication circuit 11 is constituted by a combination of operational amplification circuits, for example, a multiplication IC or the like.

[0054]

According to the present invention, in the case of the detecting device, the received signal is set as the correlated signal at each time of the detecting cycle,
With a configuration in which a signal of a promised waveform delayed by a small amount of time is used as a correlation signal, a detection signal that has been subjected to correlation detection processing can be obtained. At the same time, since pulse compression processing can be performed, reflection detection and transmission detection can be performed using a pulse-compressed S / N detection signal.

Also, in the case of the signal detection device, the input signal is used as the correlated signal, and the signal of the promised waveform is used as the correlation signal.
Similarly, by simply modifying the multiplication circuit, it is possible to obtain a detection signal having a good S / N by simultaneously performing the correlation detection processing and the pulse compression processing.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention;

FIG. 2 is an operation waveform diagram of a main part of the first embodiment of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the present invention;

FIG. 4 is an operation waveform diagram of a main part according to a second embodiment of the present invention;

FIG. 5 is a block diagram of a modified embodiment of the present invention.

FIG. 6 is a signal waveform diagram of a main part of a conventional technique.

FIG. 7 is a signal waveform diagram of a main part of a conventional technique.

FIG. 8 is a signal waveform diagram of a main part of a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 detection period circuit 1A detection period signal 2 transmission circuit 21 transmission waveform circuit 22 power amplification circuit 2A transmission signal 3 transmission antenna 4 transmission electromagnetic wave 5 ground surface 6 underground 7A, 7B, 7C underground object 8 reflected electromagnetic wave 9 reception antenna 9A Received signal 10 Amplification circuit 10A Received signal 11 Multiplication circuit 11A Multiplication signal 12 Variable delay circuit 12A Delay signal 13 Correlation signal circuit 13A Correlation signal 14 Integration circuit 14A Integration signal 15 Sample holding circuit 15A Detection signal 16 Display circuit 50 Transmission circuit section Reference Signs List 60 Receiving side circuit unit 70 Control / display circuit unit 100 Underground exploration radar

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-240943 (JP, A) JP-A-5-288834 (JP, A) JP-A-5-312938 (JP, A) JP-A-2- 165086 (JP, A) JP-A-2-27285 (JP, A) JP-A-3-142392 (JP, A) JP-A-2-44277 (JP, A) JP-A 1-282490 (JP, A) JP-A-1-280279 (JP, A) JP-A-63-174082 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S ⁷ /00-7/42 G01S 13/00 -13/95

Claims (8)

(57) [Claims] 1. A short than the cycle repeats at a required period
A correlation detection type detection device that obtains a required detection signal by correlating a reception signal of a reflected wave or a transmission wave obtained by transmitting a transmission signal having a promised waveform of a long time with the promised waveform , A fixed-period transmission means for transmitting the transmission signal at a constant cycle, and a variable-delay correlation signal means for obtaining, as a correlation signal, a delayed promised waveform signal obtained by sequentially delaying the promised waveform by a small amount of time at each time of the cycle. And a multiplication means for obtaining the detection signal based on a multiplication signal obtained by multiplying the reception signal as a correlated signal and the correlation signal for each cycle. 2. A cycle shorter than the cycle repeated at a required cycle.
A correlation detection type detection device that obtains a required detection signal by correlating a reception signal of a reflected wave or a transmission wave obtained by transmitting a transmission signal having a promised waveform of a long time with the promised waveform , A fixed-period correlation signal means for obtaining a signal of the promised waveform as a correlation signal each time with a fixed period, and a variable delay transmission means for transmitting the transmission signal by sequentially delaying the period by a small amount of time each time And a multiplying means for obtaining the detection signal based on a multiplication signal obtained by multiplying the correlation signal with the correlation signal for each of the periods, using the reception signal as a correlated signal. . 3. A process according to claim 1 or請 characterized by including the multiplication means for performing an analog value the hanging calculated
The correlation detection type detection device according to claim 2. 4. The method of claim 1, characterized in that it comprises the multiplication means for performing the digital value of the hanging calculation or
The correlation detection type detection device according to claim 2 . 5. A cycle shorter than the cycle repeated at a required cycle.
A correlation-type signal detection device configured to obtain a required detection signal by correlating a reception signal including a signal having a promised waveform having a long time with the promised waveform , wherein the reception signal has a constant period. a constant period receiving means for obtaining a variable delay correlation signal means for obtaining a delayed commitment waveform signal the promised waveform sequentially delayed by a small amount time each time the cycle as a correlation signal, the received signal as an object to be correlation signal And a multiplication means for obtaining the detection signal based on a multiplication signal obtained by multiplying the correlation signal for each cycle. 6. A cycle shorter than the cycle repeated at a required cycle.
A correlation-type signal detection device in which a received signal including a signal having a promised waveform having a long time is correlated with the promised waveform to obtain a required detection signal, wherein the cycle is set to a constant cycle, and Constant-period correlation signal means for obtaining the signal of the promised waveform as a correlation signal, variable-delay reception means for obtaining the reception signal obtained by sequentially delaying the cycle by a small amount of time each time, and the reception signal as a correlated signal, A correlation signal detection device, comprising: multiplication means for obtaining the detection signal based on a multiplication signal obtained by multiplying the correlation signal for each cycle. 7. The apparatus according to claim 5 , further comprising said multiplying means for performing said multiplication by an analog value.
The correlation-type signal detection device according to claim 6 . 8. The apparatus according to claim 5 , further comprising the multiplying means for performing the multiplication by a digital value.
The correlation-type signal detection device according to claim 6 .