JPH0522187B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a two-phase modulation system that aims to measure the distance to the target by emitting radio waves to a target and receiving the reflected radio waves. The present invention relates to a synchronization pull-in device that requires high-speed synchronization with high secrecy, and a distance measuring radar using the synchronization pull-in device.

(Summary of the Invention) The present invention uses a pseudorandom code sequence to transmit a signal created by O, π two-phase quadrature modulation or balanced quadrature modulation toward a target, and demodulates the reflected signal from the target. A synchronization pull-in device that makes it possible to track a target signal by synchronizing signals reflected from a target at high speed using a pseudo-random code sequence consisting of two or more types, and the use of the synchronization pull-in device Along with distance measurement,
The present invention provides a ranging radar with reduced ambiguity.

(Prior Art) FIG. 2 shows a conventional example of a distance measuring radar, and this conventional example will be explained first. The second transmission source output 117, which is the output signal of the second transmission source 116, is transmitted to the second modulation/demodulation signal generator 17 in the seventh phase modulator 130.
2 using the second modulation signal 171 which is the output of
It is phase modulated and becomes the seventh phase modulator output 131, which is input to the second transmitter 122 and amplified to become the second
The transmitter output becomes 123, and the second transmitting antenna 11
0 becomes the second transmission signal 111 and is transmitted to the target.

The second reception signal 113, which is a reflected wave from the target, is received by the second reception antenna 114, becomes the second reception antenna output 115, and is input to the fourth power divider 142, where the power of the reception signal is distributed and the fourth power is output. They become a distributor first output 143 and a fourth power distributor second output 145. Fourth power divider first output 143
is the eighth phase modulator 13 in the fifth demodulator 154
The fifth demodulation signal 135, which is the output of
5, which is input to the fifth intermediate frequency amplifier 162 and amplified to become the fifth intermediate frequency amplifier output 163, and one output of the fifth intermediate frequency amplifier output 163 is input to the third synchronous detector 124.

The fourth output which is the other output of the fourth power divider 142
The power divider second output 145 is multiplied by the sixth demodulation signal 137, which is the output of the ninth phase modulator 136, as the demodulation signal in the sixth demodulator 156, and becomes the sixth demodulator output 157. It is input to an intermediate frequency amplifier 164 and amplified to become a sixth intermediate frequency amplifier output 165, and the sixth intermediate frequency amplifier output 165 is input to a third synchronous detector 124 and synchronously detected using the fifth intermediate frequency amplifier output 163 as a reference signal. This becomes the third synchronous detector output 125, which is an error signal for synchronization, and is input to the second modulation/demodulation signal generator 170. The first signal 173 for second demodulation is the output of the second modulation/demodulation signal generator 170
becomes a modulation signal of the second local oscillator output 183 which is the output of the second local oscillator 182 in the eighth phase modulator 134, and is phase modulated in the eighth phase modulator 134 to become a fifth demodulation signal 135. The second signal 175 for demodulation, which is the other output of the second modulation/demodulation signal generator 170, becomes a modulation signal for the second local oscillator output 183, is phase modulated in the ninth phase modulator 136, and is used for the sixth demodulation. The signal becomes signal 137.

The other output of the fifth intermediate frequency amplifier output 163 is input to an amplitude detector 190, where it is amplitude detected and becomes an amplitude detector output 191, which is used for target detection.

(Problem to be Solved by the Invention) In the conventional example shown in FIG.
and the second received signal 113 _respectively X ₁₁₁ =a(t ₎ sinωt...( ₁ ) ): pseudorandom code sequence, T ₀ : propagation time from transmission to reception, ω: angular frequency of carrier wave). If the period of pulse modulation of the transmission signal is τ _p and the period of phase modulation is τ _q , then a(t)=q(ω _q t) p(ω _p t) (3). However, ω _q =2πf _q …(4) ω _p =2πf _p …(5) τ _q =1/f _q …(6) τ _p =1/f _p …(7). When only phase modulation is used in equations (1) and (2), equation (3) may be set to p(ω _p t)=1.

The fifth demodulation signal ₁₃₅ is _{expressed as}
out of synchronization). The sixth demodulation signal ₁₃₇ is _expressed as
(pseudorandom code sequence orthogonal to ). The fifth intermediate frequency amplifier output 163 is obtained by integrating the second received signal 135 and the fifth demodulation signal 135 after the multiplication operation, so that X ₁₆₃ =ρ _aa (τ) sin ω _i t (10). However, ω _i =ω−ω _r …(11) ρ _aa (τ) = ∫a(t)a(t+τ)dt …(12), and ρ _aa (τ) is the autocorrelation function regarding a(t). be.

The sixth intermediate frequency amplifier output 165 is obtained by integrating the second received signal 113 and the sixth demodulation signal 137 after the multiplication operation, so that X ₁₆₅ =η _aA (τ) sinω _i t (13). However, η _aA (τ)=∫a(t)A(t+τ)dt …(14), and since a(t) and A(t) are mutually orthogonal signals, ∫a(t)A(t )dt=0 (15). However, η _aA (τ) is a self-orthogonal correlation function between a(t) and A(t).

Since the third synchronous detector output 125 is the average after the multiplication operation of the fifth intermediate frequency amplifier output 163 and the sixth intermediate frequency amplifier output 165, X ₁₂₅ = E[η _aA (τ) ρ _aa (τ)]... (16) (However, E[ ] represents the average). This is an error signal called S-shaped characteristic necessary for synchronization.

Considering the example of a high repetition pulse Doppler radar, the phase modulation period τ _q and pulse modulation period τ _p used in the following description are shown in FIG. 4A or B. Here, FIG. 4A shows an example of pulse-by-pulse phase modulation, and FIG. 4B shows an example of intra-pulse phase modulation.

In high-repetition pulsed Doppler radar, the most sensitive signal is received at the Doppler frequency, which is unaffected by the spectrum of the transmitted signal, between the center frequency of the transmitted signal and the first side band of pulse modulation or phase modulation. If this is necessary, the repetition frequency _fq of phase modulation and the pulse repetition frequency _fp must satisfy the following relationship from the assumed maximum Doppler frequency _fdnax .

f _dnax <Min(f _q , f _p )/2 (17). However, = f _q , f _q < f _p Min (f _q , f _p )...(18) = f _q , f _p > f _p . If the signal from the target can be received between the transmitted signals and the next transmitted signal, the received pulse signal can be detected from the received signal without ambiguity (uncertainty as to how many previous transmitted pulses have reflected from the target). Since the distance to the target can be measured, the condition under which the distance to the target can be measured without ambiguity is R _nax (m) < 150Max (τ _q , τ _p ) (μs) (19). However, = τ _q , τ _p > τ _p Max (τ _q , τ _p ) ...(20) = τ _q , τ _p < τ _p . When the relative speed between the target and the radar is high,
Due to the relationship in equation (17), Doppler radar can only shorten the period of pulse modulation or phase modulation, which makes distance measurement difficult.

Including the conventional example shown in Figure 2, high repetition pulse
The problems that need to be solved with Dotsupura radar are summarized as follows.

(a) It is possible to measure distances over long distances while satisfying the conditions for the high repetition pulse Doppler radar in equation (17).

(b) Shorten the synchronization pull-in time and shorten the time required for distance measurement.

(c) By effectively using transmission bandwidth,
Improve the confidentiality of transmitted signals and anti-jamming ability.

Simultaneous solutions to these problems are strongly desired.

(Means for Solving the Problems) In order to solve these problems, the synchronization pull-in device of the present invention uses a transmitting pseudorandom code sequence a(t) generated by a transmitting code sequence generator to
a(t)sin f(ωt) created by two-phase modulation or balanced modulation of π (where f(ωt): function of ωt)
A pseudo-random code sequence a(t) generated by a reception code sequence generator and the pseudo-random code sequence a(t) in order to transmit a radio wave type signal including Using each signal of pseudorandom code sequence A(t) which is orthogonal to a(t+
τ) sin f(ω _r t) and A(t+τ) sin f(ω _r t)
Using each demodulation signal in Synchronization is achieved by feeding back the error signal obtained by multiplicative detection (or FET detection) of intermediate frequency signals to the demodulation code sequence generator.
Two or more types of pseudorandom code sequences having different periods generated from the transmitting code sequence generator and the receiving code sequence generator are synchronized with each other in the transmitting code sequence generator and the receiving code sequence generator. When receiving a reflected signal from a transmitted target, the pseudo-random code sequence on the transmitting side and the pseudo-random code sequence on the receiving side are switched between each other, and the received signal and the pseudo-random code sequence on the receiving side are switched between each other. By synchronizing each other, the effective code length or period length is lengthened.

Further, the ranging radar of the present invention uses the above-mentioned synchronization pull-in device, and provides a reference signal that is simultaneously output from the pseudo-random code sequence generator on the transmitting side and a reference signal that is simultaneously output from the pseudo-random code sequence generator on the receiving side. The distance measurement range of the radar is increased by using the time difference or phase difference between the two.

Next, the basic principle of the present invention will be explained using the embodiment shown in FIG.

The transmitted signal 11 and the received signal 13 are respectively set as follows: _{X 11} =a(t+T ₀ )sin[ω(t+T ₀ )]...(21) The first demodulation signal 33 is set as X ₃₃ =a(t+τ)cosω _r t (23). The second demodulation signal 35 is set as X ₃₅ =A(t+τ) cosω _r t (24). Since the first intermediate frequency amplifier output 63 is created by integrating the received signal 13 and the first demodulation signal 33 after the multiplication operation in the first demodulator 54, X ₆₃ =ρ _aa (τ) sinω _r t...( 25) becomes. However, ρ _aa (τ)=∫a(t)a(t+τ)dt (26), and ρ _aa (τ) is an autocorrelation function regarding a(t).

Since the second intermediate frequency amplifier output 65 is created by integrating the received signal 13 and the second demodulation signal 35 after the multiplication operation in the second demodulator 56, X ₆₅ =η _aA (τ) sinω _r t...( 27) becomes. However, η _aA (τ) = ∫a(t)A(t+τ)dt …(28), and since a(t) and A(t) are made of mutually orthogonal signals, ∫a(t)A (t)dt=0 (29), and η _aA (τ) is an autoorthogonal correlation function between a(t) and A(t)(t).

The first synchronous detector output 25 is the first of the first intermediate frequency amplifier output 63 and the second intermediate frequency amplifier output 65.
Since it is created by the average after the multiplication operation in the synchronous detector 24, X ₂₅ =E[η _aA (τ) ρ _aa (τ)] (30). The first synchronous detector output 25 has what is called the S-shaped characteristic of the discriminator, and is an error signal necessary for synchronization.

(Function) From the above explanation, it has been explained that it is possible to configure a negative feedback loop for synchronizing with the received signal 13, so a method for expanding the measurable distance will be explained.

In the example of the signal waveform diagram of FIG. 3, it is assumed that two types of pseudorandom code sequences having different periods are used: a 5-bit code sequence for modulation 91a and a 7-bit code sequence for modulation 91b. Here, the code sequence 91a
and 91b are mutually synchronized within the transmission code sequence generator 90. First, a 2-phase modulated signal is transmitted using the 5-bit code sequence 91a for modulation, and the received signal is converted into the 5-bit code sequence 71a for demodulation.
The voltage controlled oscillator 2 is demodulated using the first synchronous detector output 25 which is an error signal necessary for synchronization.
0 and adjusts the clock of the reception code sequence generator 70 to achieve a synchronized state. Thereafter, a signal subjected to two-phase modulation using the 7-bit modulation code sequence 91b is transmitted to the same target, and the received signal is demodulated using the 7-bit demodulation code sequence 71b, and the signal is transmitted to the same target. Both code sequences are brought into a synchronized state (however, the code sequences 71a and 71b are generated in synchronization with each other within the reception code sequence generator 70). Since the same voltage controlled oscillator 20 is used when both code sequences are synchronized with respect to the same target, both the demodulating 5-bit code sequence 71a and the demodulating 7-bit code sequence 71b approach the target at the same speed. or move away. For example, when the relationship between the demodulating 5-bit code sequence 71a and the demodulating 7-bit code sequence 71b is as shown in FIG. 3, the following relationship is satisfied.

5M+m=7N+n…(31) However, M and N are positive integers.

The physical meanings of m and n will be explained. From Figure 3, if the pulse width is 1 bit, the first
Since the pulse interval between the reference signal 93 and the first reference signal for demodulation 75 is 0 bits, m = 0 (32), and the pulse interval between the second reference signal for modulation 95 and the second reference signal for demodulation 77 is 3 bits, so n=3...(33). The smallest positive integer M that satisfies equation (31),
N is M=2...(34) N=1...(35) At that time, the distance from the radar to the target is
Rt is R _t (m)=150×10×τ _b (μs) (36). However, τ _b is a 1-bit pulse width as shown in FIG.

In the case of the example in FIG. 3, the number of bits that serve as the reference for reaching the target that can be measured without ambiguity from the waveforms of the first reference signal for modulation 93 and the second reference signal for modulation 95 in FIG. 3 is LCM (5, 7) = 35 (bits) As shown in (37), the period is 35 bits, so the maximum distance that can be measured without ambiguity is R _nax (m) < 150×35×τ _b (μs) …( 38) becomes. However, LCM is the least common multiple.

By using two types of code sequences, the time required for synchronization is proportional to the number of bits in the code sequence, so from the relationship 5+7<LCM(5,7)...(39), in the case of 5 bits, the code If they are shifted five times, the maximum value of the received signal (temporal coincidence of signs)
In the case of 7 bits, by shifting the signs 7 times, you can check the maximum value of the received signal.
In the case of bits, the maximum value of the received signal cannot be confirmed unless the codes are shifted 35 times, so it is much shorter to perform 5 bits and 7 bits twice than to do 35 bits once. Ru. Furthermore, it is possible to measure long-distance targets while satisfying the high-repetition Doppler radar condition of equation (17).

(Example) Examples of the present invention will be described below with reference to the drawings.

In FIG. 1, source output 17, which is the output of transmitting source 16, is input to a first phase modulator 30. In FIG.
In the first phase modulator 30, the transmission source output 17 becomes the first phase modulator output 31, which is phase-modulated using the modulation code sequence 91, which is the output of the transmission code sequence generator 90, as a modulation signal. The signal 11 is input to the transmitter 22 and amplified to become a transmitter output 23, and then transmitted from the transmitting antenna 10 toward the target.

The received signal 13, which is a reflected wave from the target, is received by the receiving antenna 14 and output from the receiving antenna output 15.
is input to the first power divider 42 and becomes the first power divider first output 43 and the first power divider second output 45. The first power divider first output 43 is
In the first demodulator 54, the first demodulation signal 33 is demodulated as a demodulation signal to become the first demodulator output 55, which is input to the first intermediate frequency amplifier 62 and amplified to produce a first intermediate frequency signal which is a narrowband signal. Amplifier output 6
3 and is input to the first synchronous detector 24 as a reference signal for the first synchronous detector 24.

The first power divider second output 45 is connected to the second demodulator 5
6 which is the output of the third phase modulator 34.
The demodulation signal 35 becomes the demodulated second demodulator output 57 as the demodulation signal, and the second intermediate frequency amplifier 6
4 and is amplified to become the second intermediate frequency amplifier output 65 which is a narrow band signal, which is then input to the first synchronous detector 2.
The first synchronous detector 24 serves as a signal for detecting the error of 4.
is inputted to the synchronous detection circuit and modulated code sequence 91
The first synchronous detector output 25 is an error signal necessary for synchronization with the first synchronous detector.

Local oscillator output 8 which is the output of local oscillator 82
3 is input to the second power divider 46 and outputs the second power divider first output 47 and the second power divider second output 4.
9, the first output 47 of the second power divider is input to the second phase modulator 32, and the first code sequence 7 for demodulation is inputted to the second phase modulator 32.
1 as a modulation signal, and becomes a first demodulation signal 33, which becomes a demodulation signal for the first demodulator 54.

Similarly, the second power divider second output 49
The signal is input to the phase modulator 34 and phase-modulated using the second demodulation code sequence 73 as a modulation signal to become a second demodulation signal 35, which becomes a demodulation signal for the second demodulator output 57.

The other output of the first intermediate frequency amplifier output 63, which is the output of the first intermediate frequency amplifier 62, is the output of the amplitude detector 2.
6, the amplitude detector 26 amplitude-detects the input signal and outputs an amplitude detector output 27, which is used to detect the target signal, and is also used by the transmitting code sequence generator 90 and the receiving code sequence generator 90. 70 as a signal for code sequence switching (switching between 91a and 91b in FIG. 3, and switching between 71a and 71b).

The first synchronous detector output 25 is passed through a low-pass filter 28
The signal is input to the low-pass filter output 29, is input to the voltage controlled oscillator 20 and becomes the voltage controlled oscillator output 21, and is input to the receiving code sequence generator 70 as a clock for the receiving code sequence generator 70. The reception code sequence generator 70 outputs a first demodulation code sequence 71 and a second demodulation code sequence 73, and the first demodulation code sequence 71 and the second demodulation code sequence 73 are orthogonal to each other. ing.
The first demodulation code sequence 71 is input to the second phase modulator 32 , and the second demodulation code sequence 73 is input to the third phase modulator 34 .

The first reference signal for demodulation 75 which is the output of the code sequence generator for reception 70 and the code sequence generator for transmission 90
The first reference signal for modulation 93 which is the output of is input to the first bit counter 84, and becomes the first bit counter output 85 which is a time difference signal and is input to the distance calculator 88. The second demodulation reference signal 77, which is the output of the reception code sequence generator 70, and the modulation second reference signal 95, which is the output of the transmission code sequence generator 90, are each input to a second bit counter 86, and the time difference is The signal becomes the second bit counter output 87 and is input to the distance calculator 88. The distance calculator 88 calculates the distance from the radar to the target corresponding to equation (36) using the first bit counter output 85 and the second bit counter output 87, and produces a distance calculator output 89.

An example of the waveform diagram in FIG. 3 will be explained. A 5-bit modulation code sequence 91a output from the transmission code sequence generator 90 is a 5-bit pseudo-random code sequence, and is used as a modulation code sequence 91 which is a signal for phase modulating the transmission signal. The 7-bit modulation code sequence 91b is a 7-bit pseudo-random code sequence, and is switched and used as the modulation code sequence 91, which is a signal for phase modulating the transmission signal. The two types of code sequences 91a and 91b are mutually synchronized within the transmission code sequence generator 90.

The demodulating 5-bit code sequence 71a, which is the output of the receiving code sequence generator 70, is a 5-bit pseudo-random code sequence, and is used as the first code sequence 71, which is a phase modulation signal, for demodulating the received signal. Ru. The demodulation 7-bit code sequence 71b is a 7-bit pseudo-random code sequence, and is switched and used as the first code sequence 71, which is a phase modulation signal for demodulating the received signal. The two types of code sequences 71a and 71b are generated by the receiving code sequence generator 7.
They are mutually synchronized within 0.

The first reference signal 93 for modulation, which is the output of the transmission code sequence generator 90, is a 5-bit code sequence 91 for modulation.
a, and further synchronized with the demodulation first reference signal 75 which is the output of the reception code sequence generator 70, the modulation first reference signal 93
The pulse interval (in this example, 0 bit) between the signal and the first reference signal for demodulation 75 is determined. However, the first reference signal for demodulation 75 is synchronized with the 5-bit code sequence for demodulation 71a. Transmission code sequence generator 9
The second modulation reference signal 95 which is the output of 0 is synchronized with the modulation 7-bit code sequence 91b, and furthermore,
When synchronized with the demodulation second reference signal 77 which is the output of the reception code sequence generator 70, the modulation second reference signal 95 and the demodulation second reference signal 77 are synchronized.
The pulse interval (in this example, 3 bits) is determined. However, the second reference signal for demodulation 77 is synchronized with the 7-bit code series for demodulation 71b.

In this way, we are trying to measure the distance to a distant target while avoiding ambiguity in the Doppler signal.

An example of the waveform diagram in FIG. 4 will be explained. FIG. 4A shows an example of pulse-by-pulse phase modulation, in which only the pulse portion of the pulse modulated signal is transmitted, and transmission of the other portions is suspended. The phase modulation signal is a pseudorandom code sequence with τ _q of 5 bits. FIG. 4B shows an example of intra-pulse phase modulation, in which only the pulse portion of the pulse modulated signal is transmitted, and transmission of the other portions is suspended. The phase modulation signal is a pseudorandom code sequence with τ _q of 5 bits. As shown in these examples, when using phase modulation of a 5-bit code sequence, there are two types: per-pulse phase modulation and intra-pulse phase modulation, and either method satisfies the pulsed Doppler radar condition of equation (17). satisfy.

(Supplementary explanation) (A) The transmission signal 11 may be pulse phase modulation or continuous wave phase modulation.

(a) As shown in FIGS. 4A and 4B, the pulse phase modulation may be per-pulse phase modulation or intra-pulse phase modulation.

(c) The distance may be determined by comparing the 5-bit code sequence for modulation 91a and the 5-bit code sequence for demodulation 71a, and the 7-bit code sequence for modulation 91b and the 7-bit code sequence for demodulation 71b to determine the bit interval.

(d) The following relationship X _x = a(t)sin f(ωt) ...(40) represents a signal whose carrier wave has an angular frequency ω, so equation (22) can be expressed as equation (40). can.

(E) In Figures 3 and 4, two types of pseudo-random code sequences are used to reduce ambiguity, but if three types of pseudo-random code sequences are used, the range of distance measurement that can be measured will be further expanded. do. For example, if a 9-bit code sequence is added to the synchronization loop described above, the number of pits that can be used as the basis for the distance to the target that can be measured without ambiguity is LCM (5, 7, 9) = 315 (bits)... As shown in (41), the period is 315 bits, so the maximum distance that can be measured without ambiguity is R _nax (m)<150×315×τ _b (μs) (42).

( _F ) In the case of _four -phase modulation, _it can be expressed as
(ωt) or the sin component a(ωt), B is an orthogonal code sequence that is paired with
(ωt) or A(ωt), the received signal can be demodulated and synchronized, so the same effect of the invention can be expected with four-phase modulation.

(G) In the embodiment shown in Figure 1, single super
Although the heterodyne method has been explained, a double super-heterodyne method may also be used.

(H) The multiplicative detector of the embodiment shown in FIG. 1 may extract the error signal by using a FET detector realized by software using a digital FET analyzer.

(k) The error signal obtained by the multiplier detector output or FET detector is E[η _aA (ωτ)ρ _aa (ωτ)], E[η _aA (ωτ)
] or E[η _aA (ωτ) ρ _aa (ωτ)].

(Effect of the invention) The effects of the present invention are as follows.

(a) Since two or more types of code sequences are used, the range of unambiguous distances associated with distance measurement increases.

(a) Since two or more types of code sequences are used, high-speed synchronization is possible, and the target signal can be captured in a short time.

(c) Since two or more types of code sequences are used, there is little possibility that the code sequence of the transmitted signal will be decoded.
The secrecy of the transmitted signal is extremely high.

(D) It is difficult to interfere with the intermediate frequency amplifier unless the transmitted signal is decrypted, so it is resistant to radio interference.

(e) Since two or more types of pseudo-random code sequences are used in the modulation signal of the transmitted signal and can be switched between them, the transmitted radio waves are highly confidential and have excellent resistance to radio interference.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG.
The figure is a block diagram of a conventional example, FIG. 3 is a waveform diagram showing an example of a signal waveform for explaining an embodiment of the present invention, and FIG. 4 is an example of a pulse phase modulation signal used in the embodiment. FIG. 10...Transmission antenna, 11...Transmission signal, 1
3...Received signal, 14...Receiving antenna, 15...
...Receiving antenna output, 16... Transmission source, 17...
Transmission source output, 20... Voltage controlled oscillator, 21...
Voltage controlled oscillator output, 22... Transmitter, 23...
Transmitter output, 24...First synchronous detector, 25...
First synchronous detector output, 26...amplitude detector, 27
...Amplitude detector output, 28...Low pass filter,
29...Low pass filter output, 30...First phase modulator, 31...First phase modulator output, 32...
Second phase modulator, 33...first demodulation signal, 34
...Third phase modulator, 35...Second demodulation signal,
42...First power divider, 43...First power divider first output, 45...First power divider second output,
46...Second power divider, 47...Second power divider first output, 49...Second power divider second output,
54...first demodulator, 55...first demodulator output,
56...Second demodulator, 57...Second demodulator output,
62...first intermediate frequency amplifier, 63...first intermediate frequency amplifier output, 64...second intermediate frequency amplifier,
65... Second intermediate frequency amplifier output, 70... Code sequence generator for reception, 71... First code sequence for demodulation, 71a... 5-bit code sequence for demodulation, 71b
... 7-bit code sequence for demodulation, 73 ... Second code sequence for demodulation, 75 ... First reference signal for demodulation, 77
...Second reference signal for demodulation, 82...Local oscillator,
83...Local oscillator output, 84...1st bit counter, 85...1st bit counter output
(n), 86...Second bit counter, 87...Second bit counter output (m), 88...Distance calculator, 89...Distance calculator output (R), 90...Transmission code Sequence generator, 91...Modulation code sequence, 91
a...5-bit code series for modulation, 91b...7-bit code series for modulation, 93...1st reference signal for modulation, 95...2nd reference signal for modulation, 110...2nd transmitting antenna, 111... ...Second transmission signal, 11
3...Second reception signal, 114...Second reception antenna, 115...Second reception antenna output, 116...
...Second transmission source, 117...Second transmission source output, 12
2...Second transmitter, 123...Second transmitter output,
124... Third synchronous detector, 125... Third synchronous detector output, 130... Seventh phase modulator, 131
...Seventh phase modulator output, 134...Eighth phase modulator, 135...Fifth demodulation signal, 136...Ninth phase modulator, 137...Sixth demodulation signal, 14
2...Fourth power divider, 143...Fourth power divider first output, 145...Fourth power divider second output, 154...Fifth demodulator, 155...Fifth demodulator output, 156...Sixth demodulator, 157...Sixth
Demodulator output, 162...Fifth intermediate frequency amplifier, 1
63...Fifth intermediate frequency amplifier output, 164...Sixth intermediate frequency amplifier, 165...Sixth intermediate frequency amplifier output, 170...Second modulation signal generator, 17
1... Signal for second modulation, 173... First signal for second demodulation, 175... Second signal for second demodulation, 182
...Second local oscillator, 183...Second local oscillator output, 190...Amplitude detector, 191...Amplitude detector output.

Claims (1)

[Claims] 1. A transmission source, a transmission code sequence generator that switches and outputs two or more types of pseudorandom code sequences a(t) with different periods, and the pseudorandom code sequence a(t).
By phase modulating using (t), O,
a(t)sin f(ωt) (where t: time, ω: angular frequency of carrier wave, f
(ωt): a function of ωt); a transmitting antenna that transmits the radio wave type signal; and a receiving antenna that receives the radio wave type signal transmitted from the transmitting antenna. and generate each signal of a pseudo-random code sequence a(t) and a pseudo-random code sequence A(t) orthogonal to the pseudo-random code sequence a(t) in order to demodulate the received signal of the receiving antenna. a(t+τ) sin f(ω r t) and A(t+τ) sin f( _{ω r} t) (However, ω _r : Center frequency of demodulation signal, τ:
Using _each demodulation signal _of Intermediate frequency signal η _aA (τ)cos whose amplitude is the correlation function
demodulation means for obtaining f(ω _i t) and further their intermediate frequency signals ρ _aa (τ) cos f(ω _i t) and η _aA (τ)
Multiplicative detection or FFT of cos f(ω _i t)
a detection means for performing detection, and synchronization is achieved by feeding back an error signal obtained as an output of the detection means to the reception code sequence generator; at this time, the transmission code sequence generator and two or more types of pseudorandom code sequences with different periods generated from the reception code sequence generator are synchronized with each other in the transmission code sequence generator and the reception code sequence generator, and the transmission signal is received. At this time, the pseudo-random code sequence on the transmitting side and the pseudo-random code sequence on the receiving side are switched to each other, and the received signal and the pseudo-random code sequence on the receiving side are synchronized with each other, thereby generating an effective code. A synchronous pull-in device characterized by increasing the length or period length. 2. A transmission source, a transmission code sequence generator that switches and outputs two or more types of pseudo-random code sequences a(t) with different periods, and the pseudo-random code sequence a(t).
By phase modulating using (t), O, π
a(t)sin f(ωt) (where t: time, ω: angular frequency of carrier wave, f
(ωt): a function of ωt); a transmitting antenna that transmits the radio wave type signal toward a target; a receiving antenna that receives a reflected wave signal from the target; For reception, generating a pseudo-random code sequence a(t) and each signal of the pseudo-random code sequence A(t) orthogonal to the pseudo-random code sequence a(t) in order to demodulate the received signal of the receiving antenna. code sequence generator and a(t) and A(t) from the receiving code sequence generator
a(t+τ) sin f(ω _r t) and A(t+τ) sin f(ω _{r t} ) created from
Using _each demodulation signal _of Intermediate frequency signal η _aA (τ)cos whose amplitude is the correlation function
demodulation means for obtaining f(ω _i t) and further their intermediate frequency signals ρ _aa (τ) cos f(ω _i t) and η _aA (τ)
Multiplicative detection or FFT of cos f(ω _i t)
a detection means for performing detection, and synchronization is achieved by feeding back an error signal obtained as an output of the detection means to the reception code sequence generator; at this time, the transmission code sequence generator and two or more types of pseudorandom code sequences with different periods generated from the reception code sequence generator are synchronized with each other in the transmission code sequence generator and the reception code sequence generator, and the transmission signal is received. At this time, the pseudo-random code sequence on the transmitting side and the pseudo-random code sequence on the receiving side are switched to each other, and the received signal and the pseudo-random code sequence on the receiving side are synchronized with each other, thereby generating an effective code. A modulation reference signal of the transmitting code sequence generator synchronized with the pseudorandom code sequence generated by the transmitting code sequence generator and the receiving code sequence using a synchronization pull-in device that increases the length or period length. Distance measurement is performed by increasing the distance measurement range by providing a calculation means for calculating distance from the time difference or phase difference between the pseudo-random code sequence generated by the generator and the demodulation reference signal of the receiving code sequence generator synchronized with the received code sequence generator. A distance measuring radar characterized by: