JPH08304531A - Fm-cw radar - Google Patents

Abstract

PURPOSE: To obtain an FM-CW radar with a wide reception dynamic range corresponding to a target from a short distance to a long distance in an environment where a clutter exists. CONSTITUTION: A radar is provided with a high-pass filter 8, where a capacitor 2 is provided as a series element and a series circuit of a coil 13 and a resistor 14 for termination is provided at the pre-stage of the capacitor 12 between a mixer 7 and a video amplifier 9 within a signal reception part 6. The rejection region of the high-pass filter 8 is overlapped to the frequency band of a video signal, video clutter and video signal are reduced, and the S/N ratio of the video signal is brought closer to a constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FM-CW radar which is mounted on a moving body such as an automobile and detects electric people, vehicles and obstacles existing around the vehicle by using radio waves.

[0002]

2. Description of the Related Art FIG. 20 is a block diagram showing a configuration of a conventional FM-CW radar. In the figure, 1 is a transmitter, 2 is a voltage controlled oscillator, 3 is a directional coupler, 4 is a modulator, and 5a.
Is a first antenna, 5b is a second antenna, 6 is a receiving unit, 7 is a mixer, 8 is a high-pass filter, 9 is a video amplifier, 10 is an A / D converter, 11 is a signal processing unit, and 12 is a signal processing unit. It is a capacitor.

Next, the operation will be described. In the transmission unit 1, the voltage controlled oscillator 2 receives the modulation signal from the modulator 4 to generate a frequency-modulated high frequency signal, and the directional coupler 3 transmits a part of the high frequency signal to the reception unit 6 as a local oscillation signal. The rest is sent to the first antenna 5a as a transmission signal. The first antenna 5a targets the transmission signal (omitted in FIG. 20)
The second antenna 5b receives the reflection from the target and outputs a reception signal. In the receiving unit 6, the mixer 7 frequency-converts the received signal and outputs a video signal having a beat frequency component according to the target distance / speed, and the high-pass filter 8, the video amplifier 9 and the A / D converter are provided. It is sent to the signal processing unit 11 via 10 as a digital signal. The signal processing unit 11 obtains target distance / speed information by frequency analysis and arithmetic processing of the digital signal. The high-pass filter 8 uses the frequency band of the video signal as a pass band and removes the DC component of the video signal leaking from the mixer 7.

The operation will be supplemented here. Figure 21
[Fig. 3] shows an operation principle diagram of a conventional FM-CW radar. In the figure, a curve a is a transmission signal and a local oscillation signal, a curve b is a reception signal, and a curve c is a video signal. In the case of an FM-CW radar, a target is irradiated with a frequency-modulated transmission signal, and the reception signal has a delay time of twice the distance to the target,
The received signal is frequency-converted (homodyne detection) by the local oscillation signal, and becomes a video signal having a beat frequency component corresponding to the target distance / speed. FIG. 22 shows the signal / clutter level of the conventional FM-CW radar when it is installed in a vehicle. In the figure, the curve a is the received signal level from the target,
The curve b is the level of clutter (hereinafter referred to as clutter) from the ground, the curve c is the video signal level at the input end of the A / D converter 10, and the curve d is the clutter at the input end of the A / D converter 10 ( Hereinafter referred to as video clutter.) Level. In order to simplify the description, the case where the own speed (hereinafter abbreviated as the own speed) and the target speed are the same, that is, the case where the relative speed = 0 is shown. In general, a radar needs a wide dynamic range as a receiving system in order to extract a target at a long distance with a small received signal level from a target at a short distance with a large received signal level. Therefore, in the conventional FM-CW radar,
If the received signal level is high, without saturating the receiving system,
In addition, gain control is performed so that the video signal level falls within the input dynamic range of the A / D converter 10. However, as in the case where the vehicle is mounted as shown in FIG. 22,
If there is clutter with a high received signal level, gain control is performed in accordance with the clutter level, so that the target received signal level at a long distance falls below the lower limit of the dynamic range of the A / D converter 10.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the M-CW radar, when the clutter level at a short distance becomes large, such as when mounted on a car, the gain control is performed according to the clutter level, so that the received signal from a long distance is A /
There is a problem that the dynamic range is not obtained as a receiving system because it is buried in the input noise of the D converter.

The present invention has been made to solve the above problem, and in a region where the S / N of a video signal has a margin, the video clutter level and the video signal level are close to the S / N limit. It is intended to obtain an inexpensive and high-performance FM-CW radar by realizing a receiving system having a wide dynamic range equivalently with a simple configuration.

[0007]

[Means for Solving the Problems] FM according to the first embodiment
The CW radar is provided with a high-pass filter configured by providing a capacitor as a series element and a series circuit of a coil and a terminating resistor as a parallel element between the mixer and the video amplifier in a stage before the capacitor.

In the FM-CW radar according to the second embodiment, a capacitor is used as a series element between a mixer and a video amplifier, a series circuit of a coil and a terminating resistor is provided as a parallel element before the capacitor, and a capacitor is provided after the capacitor. A high-pass filter constituted by providing coils as parallel elements was provided.

The FM-CW radar according to the third embodiment includes an terminating voltage follower circuit in which a terminating resistor is provided as a parallel element between the mixer and the video amplifier in the preceding stage of the operational amplifier and the terminating voltage follower circuit. A high-pass filter constituted by providing a capacitor as a series element in the subsequent stage was provided.

The FM-CW radar according to the fourth embodiment includes an terminating type voltage follower circuit in which a terminating resistor is provided as a parallel element between the mixer and the video amplifier, and an terminating resistor is provided in front of the operational amplifier, and a terminating type voltage follower circuit. A high-pass filter was provided in which a capacitor was provided as a series element in the latter stage and a coil was provided as a parallel element in the former stage of the capacitor.

The FM-CW radar according to the fifth embodiment includes an terminating voltage follower circuit having a terminating resistor as a parallel element between the mixer and the video amplifier and a terminating resistor in front of the operational amplifier, and a terminating voltage follower circuit. A high-pass filter was provided, in which a capacitor was provided as a series element in the latter stage, and a coil was provided as a parallel element in the front and rear stages of the capacitor.

The FM-CW radar according to the sixth embodiment includes an terminating voltage follower circuit in which an terminating resistor is provided as a parallel element between the mixer and the video amplifier in the preceding stage of the operational amplifier and the terminating type voltage follower circuit. A high-pass filter was provided in which a capacitor was provided as a series element in the latter stage, and a series circuit of a coil, a capacitor, and a resistor was provided as a parallel element in the preceding stage of the capacitor.

In the FM-CW radar according to the seventh embodiment, a voltage follower circuit by an operational amplifier is provided between a mixer and a video amplifier, and a capacitor is provided as a series element in the subsequent stage of the voltage follower circuit, and a coil is provided in parallel in the preceding stage of the capacitor. And a high-pass filter configured as described above.

The FM-CW radar according to the eighth embodiment includes a high-pass filter having a terminating resistor provided as a parallel element between the mixer and the video amplifier in front of the active filter including the operational amplifier, the resistor and the capacitor. It was

The FM-CW radar according to the ninth embodiment includes a high-pass filter composed of an operational amplifier, an active filter including a resistor and a capacitor, between a mixer and a video amplifier.

The FM-CW radar according to the tenth embodiment is
Between the mixer and the first video amplifier, a second video amplifier and a high-pass filter having a capacitor as a series element were provided.

The FM-CW radar according to the eleventh embodiment is
A high-pass filter having a second video amplifier and a capacitor as a series element and a coil as a parallel element before the capacitor was provided between the mixer and the first video amplifier.

The FM-CW radar according to the twelfth embodiment is
The second video amplifier and the capacitor as a series element were provided between the mixer and the first video amplifier, and a high-pass filter constituted by arranging a coil as a parallel element before and after the capacitor was provided.

The FM-CW radar according to the thirteenth embodiment is
Between the mixer and the first video amplifier, equipped with a second video amplifier and a capacitor as a series element, and a high-pass filter configured by providing a series circuit of a coil, a capacitor and a resistor as a parallel element in the preceding stage of the capacitor. It was

The FM-CW radar according to Embodiment 14 is
A coil is a series element between the mixer and the video amplifier,
A low-pass filter configured by installing a series circuit of a capacitor and a terminating resistor as a parallel element in the front stage of the coil, and a capacitor as a parallel element in the rear stage of the coil, and the capacitor as a series element, and the coil and termination in the front stage of the capacitor. A high-pass filter constituted by providing a series circuit of resistors for use as parallel elements was provided.

The FM-CW radar according to the fifteenth embodiment is
Between the mixer and the video amplifier, a low-pass filter composed by arranging a terminating resistor as a parallel element before the active filter consisting of an operational amplifier, a resistor and a capacitor, and a capacitor as a series element, and a coil as a parallel element before the capacitor. And a high-pass filter configured as described above.

The FM-CW radar according to the sixteenth embodiment is
Between the mixer and the video amplifier, a low-pass filter composed of an operational amplifier, an active filter consisting of a resistor and a capacitor, and a high-pass filter composed of a capacitor as a series element and a coil as a parallel element before the capacitor are provided. It was

The FM-CW radar according to the seventeenth embodiment is
A low-frequency band composed of a coil as a series element between the mixer and the first video amplifier, a series circuit of a capacitor and a terminating resistor as a parallel element in the front stage of the coil, and a capacitor as a parallel element in the rear stage of the coil. The high-pass filter was configured by using a pass filter, a second video amplifier, and a capacitor as a series element, and providing a coil as a parallel element before the capacitor.

The FM-CW radar according to Example 18 is
Between the mixer and the first video amplifier, a low-pass filter configured by arranging a terminating resistor as a parallel element before the active filter consisting of an operational amplifier, a resistor, and a capacitor, a second video amplifier, and a capacitor in series. In addition, a high pass filter constituted by arranging a coil as a parallel element before the capacitor was provided.

The FM-CW radar according to Example 19 is
Between the mixer and the first video amplifier, a low-pass filter composed of an operational amplifier, an active filter consisting of a resistor and a capacitor, a second video amplifier, and a capacitor as a series element, and a coil in front of the capacitor as a parallel element. A high-pass filter constructed and provided was provided.

[0026]

According to the first embodiment of the present invention, a high-pass filter having a capacitor as a series element and a series circuit of a coil and a terminating resistor provided as a parallel element in the preceding stage of the capacitor provides a short range, that is, a low frequency range. It is possible to lower the video clutter (hereinafter, referred to as low frequency band) and the video signal, and to bring the S / N of the video signal close to a constant value. Even if there is no gain control from a short distance to a long distance, The signal can be compressed and the dynamic range of the receiving system can be broadened equivalently.

According to the second embodiment of the present invention, a capacitor is used as a series element, a series circuit of a coil and a terminating resistor is provided as a parallel element before the capacitor, and a coil is provided as a parallel element after the capacitor. The high-pass filter can make the S / N of the video signal close to a constant value, and equivalently widen the dynamic range of the receiving system.

According to the third embodiment of the present invention, an operational amplifier and a terminating voltage follower circuit in which a terminating resistor is provided as a parallel element in the preceding stage of the operational amplifier and a capacitor as a series element in the subsequent stage of the terminating voltage follower circuit are provided. The configured high-pass filter can reduce the amount of video signal and video clutter rejection in the low frequency band, can bring the S / N of the video signal close to a constant value, and equivalently widen the dynamic range of the receiving system.

According to the fourth embodiment of the present invention, an operational amplifier and a terminating voltage follower circuit in which a terminating resistor is provided as a parallel element in the preceding stage of the operational amplifier, and a capacitor as a series element in the latter stage of the terminating voltage follower circuit are provided. The S / N ratio of the video signal can be brought close to a constant value by a high-pass filter formed by providing a coil as a parallel element in the preceding stage of the capacitor, and the dynamic range of the receiving system can be broadened equivalently.

According to the fifth embodiment of the present invention, an operational amplifier and a terminating voltage follower circuit in which a terminating resistor is provided as a parallel element in the preceding stage of the operational amplifier, and a capacitor as a series element in the subsequent stage of the terminating voltage follower circuit are provided. The S / N ratio of the video signal can be brought close to a constant value by a high-pass filter configured by providing coils as parallel elements in the front and rear stages of the capacitor, and the dynamic range of the receiving system can be broadened equivalently.

According to the sixth embodiment of the present invention, an operational amplifier and a terminating voltage follower circuit in which a terminating resistor is provided as a parallel element in the preceding stage of the operational amplifier, and a capacitor as a series element in the subsequent stage of the terminating voltage follower circuit are provided. A high-pass filter configured by connecting a series circuit of a coil, a capacitor, and a resistor as a parallel element in the preceding stage of the capacitor makes the amount of rejection of the video signal and the video clutter in a specific frequency band constant, and the S / N of the video signal. Can be brought close to a constant value, and the dynamic range of the receiving system can be broadened equivalently.

According to the seventh embodiment of the present invention, a high-pass filter constructed by providing a voltage follower circuit by an operational amplifier, a capacitor as a series element at the rear stage of the voltage follower circuit, and a coil as a parallel element at the front stage of the capacitor. As a result, the S / N ratio of the video signal can be brought close to a fixed value, and the dynamic range of the receiving system can be broadened equivalently.

According to the eighth embodiment of the present invention, the S / N ratio of the video signal is made constant by the high-pass filter constituted by arranging the terminating resistor as a parallel element before the active filter including the operational amplifier, the resistor and the capacitor. It is possible to bring them closer to each other and equivalently widen the dynamic range of the receiving system.

According to the ninth embodiment of the present invention, the S / N ratio of the video signal can be brought close to a constant value by the high-pass filter composed of the operational amplifier, the active filter including the resistor and the capacitor, and equivalently, the receiving system Wide dynamic range.

According to the tenth embodiment of the present invention, a second video amplifier, a capacitor as a series element, and a high-pass filter constituted by providing a coil as a parallel element in the preceding stage of the capacitor are used for low-frequency video. The amount of signal and video clutter rejection can be reduced, the S / N ratio of the video signal can be brought close to a fixed value, and the dynamic range of the receiving system can be broadened equivalently.

According to the eleventh embodiment of the present invention, the S / V ratio of the video signal is reduced by the high-pass filter constituted by the second video amplifier and the capacitor as the series element and the coil as the parallel element before the capacitor. It is possible to make N close to a constant value and equivalently widen the dynamic range of the receiving system.

According to the twelfth embodiment of the present invention, the second video amplifier and the capacitor are serial elements, and the high-pass filter constituted by providing the coils as parallel elements in the front and rear stages of the capacitor is used to output the video signal. It is possible to make the S / N close to a constant value, and equivalently widen the dynamic range of the receiving system.

According to the thirteenth embodiment of the present invention, a high-pass filter having a second video amplifier and a capacitor as a series element, and a series circuit of a coil, a capacitor and a resistor provided as a parallel element before the capacitor. As a result, the amount of rejection of the video signal and the video clutter in a specific frequency band can be made constant, and the S / N of the video signal can be made close to a constant, and the dynamic range of the receiving system can be broadened equivalently.

According to the fourteenth embodiment of the present invention, the coil is used as a series element, the series circuit of the capacitor and the terminating resistor is provided as a parallel element in the front stage of the coil, and the capacitor is provided as a parallel element in the rear stage of the coil. The S / N ratio of the video signal is reduced by a low-pass filter and a high-pass filter that is composed of a capacitor as a series element and a series circuit of a coil and a terminating resistor as a parallel element in the preceding stage of the capacitor.
Can be brought close to a constant value, and the dynamic range of the receiving system can be broadened equivalently.

According to the fifteenth embodiment of the present invention, a low-pass filter formed by arranging a terminating resistor as a parallel element in the front stage of an active filter including an operational amplifier, a resistor and a capacitor, and a capacitor as a series element, and a front stage of the capacitor. The S / N ratio of the video signal can be brought close to a constant value by a high-pass filter having a coil provided as a parallel element, and the dynamic range of the receiving system can be broadened equivalently.

According to the sixteenth embodiment of the present invention, a low-pass filter composed of an operational amplifier, an active filter consisting of a resistor and a capacitor, and a capacitor are series elements,
The S / N ratio of the video signal can be brought close to a constant value by a high-pass filter formed by providing a coil as a parallel element in the preceding stage of the capacitor, and the dynamic range of the receiving system can be broadened equivalently.

According to the seventeenth embodiment of the present invention, the coil is a serial element, the series circuit of the capacitor and the terminating resistor is provided as a parallel element in the preceding stage of the coil, and the capacitor is provided as a parallel element in the subsequent stage of the coil. The S / N ratio of the video signal is reduced by a high-pass filter that is configured by using a low-pass filter, a second video amplifier, and a capacitor as a series element and providing a coil as a parallel element before the capacitor.
Can be brought close to a constant value, and the dynamic range of the receiving system can be broadened equivalently.

According to the eighteenth embodiment of the present invention, a low-pass filter having a terminating resistor provided as a parallel element in the preceding stage of an active filter including an operational amplifier, a resistor and a capacitor, a second video amplifier and a capacitor are provided. The S / N ratio of the video signal can be brought close to a constant value by a high-pass filter configured by using a series element and a coil provided as a parallel element in the preceding stage of the capacitor, and equivalently, the dynamic range of the receiving system can be widened.

According to the nineteenth embodiment of the present invention, a low-pass filter composed of an operational amplifier, an active filter including a resistor and a capacitor, a second video amplifier, a capacitor as a series element, and a coil in parallel with a preceding stage of the capacitor. By the high-pass filter configured as an element,
The S / N ratio of the video signal can be brought close to a constant value, and the dynamic range of the receiving system can be equivalently widened.

[0045]

EXAMPLES Example 1. FIG. 1 shows an FM-C according to a first embodiment of the present invention.
The block diagram of a W radar apparatus is shown. In the figure, 1-1
2 is the same as the conventional FM-CW radar, and 13
Is a coil, and 14 is a terminating resistor.

Next, the operation will be described. In the transmission unit 1, the voltage controlled oscillator 2 receives the modulation signal from the modulator 4 to generate a frequency-modulated high frequency signal, and the directional coupler 3 transmits a part of the high frequency signal to the reception unit 6 as a local oscillation signal. The rest is sent to the first antenna 5a as a transmission signal. The first antenna 5a irradiates the target with the transmission signal, and the second antenna 5b receives the reflection from the target and outputs the reception signal. In the receiving unit 6, the mixer 7 frequency-converts the received signal and outputs a video signal having a beat frequency component according to the target distance / speed, and the high-pass filter 8, the video amplifier 9 and the A / D converter are provided. It is sent to the signal processing unit 11 via 10 as a digital signal. The signal processing unit 11 obtains target distance / speed information by frequency analysis and arithmetic processing of the digital signal. The high-pass filter 8 has a capacitor 12 as a series element, and a coil 13 is provided in front of the capacitor 12.
And a terminating resistor 14 are connected in series as a parallel element. As shown in FIG. 21, the frequency of the video signal is the frequency difference between the local oscillation signal and the reception signal input to the mixer 7, and the transmission signal is transmitted from the first antenna 5a except for the Doppler frequency generated by the movement of the target. However, it is determined by the time until the reception signal reflected by the target is input to the mixer 7. The longer this time, that is, the longer the distance to the target, the larger the value. Further, the reception signal level decreases as the distance to the target increases. That is, when detecting a long-distance target, the video signal has a high frequency and a low level. Also, when detecting a short-range target, the frequency of the video signal is low and the level is high.
In the present embodiment, the high-pass filter 8 allows a short-distance target having a margin with respect to the minimum signal level detectable by the signal processing unit 11, that is, a target existing at a low frequency,
It reduces the signal level of video clutter that is present at low frequencies and saturates the receiving system. In this way, the signal level of the video clutter that saturates the reception signal and the reception system with a margin of S / N can be reduced, and it is possible to detect a long-distance target without lowering the signal level. A wide dynamic range can be secured equivalently at the input end of the receiver 6.

Here, the function of the high-pass filter 8 will be supplemented. FIG. 23 shows the signal / clutter level of the FM-CW radar according to the first embodiment of the present invention when mounted on a vehicle. In the figure, a curve a is the received signal level from the target, a curve b is the received clutter level from the ground, a curve c is the video signal level at the input end of the A / D converter 10, and a curve d is the A / D converter 10. It is the video clutter level at the input end. Here, in order to simplify the description, the case where the own speed and the target speed are the same is shown. In the FM-CW radar of the present invention, since the video clutter and the video signal in the low frequency band are blocked by the high pass filter 8, the maximum signal level and the minimum signal level at the input end of the A / D converter 10 are obtained. (Noise level of A / D converter 10) The difference is small. Therefore, a wide dynamic range is secured at the input end of the receiving unit 6 as in the conventional case, and A /
Since the input end of the D converter 10 may be narrow, a dynamic range is equivalently secured as a receiving system. Next, the stop band and the stop amount of the high pass filter 8 will be described. In order for the signal processing unit 11 to calculate the target distance / speed, the detection S / N is necessary, and the S / N of the video signal at a short distance is larger than the detection S / N.
High-pass filter 8 detects S / N of video signal S / N
It can block near-field video signals until they are equal to. Therefore, short-distance video clutter can be blocked by the same amount as the video signal. In this way, the S / N of the video clutter level and the video signal level is lowered in a region where the S / N of the video signal has a margin, and the S / N of the video signal is brought close to a constant value.

Example 2. FIG. 2 shows a block diagram of an FM-CW radar device according to a second embodiment of the present invention. In the figure, 1 to 12 are the same as those of a conventional FM-CW radar, 13 is a coil, and 14 is a terminating resistor.

Also in this case, similarly to the first embodiment, the capacitor 12 is a series element, the series circuit of the coil 13 and the terminating resistor 14 is provided as a parallel element before the capacitor 12, and the coil 13 is provided after the capacitor 12. Is provided as a parallel element, it is possible to prevent the S / N of the video signal in the low band from approaching a constant value by the high-pass filter 8, which compensates for the narrow dynamic range of the A / D converter 9, and equivalently A wide dynamic range is secured at the input end of the receiver 6.

Further, even if the clutter / target signal at a short distance is large, the amount of blocking in the low frequency band can be easily increased, so that the S / N ratio of the low frequency band video signal can be brought close to a constant value.

Example 3. FIG. 3 shows a block diagram of an FM-CW radar device according to a third embodiment of the present invention. In the figure, 1 to 12 are the same as those of a conventional FM-CW radar, 14 is a terminating resistor, 15 is an operational amplifier, and 16 is a terminating voltage follower circuit.

Also in this case, similarly to the first embodiment, the operational amplifier 15 and the terminating voltage follower circuit 16 in which the terminating resistor 14 is provided as a parallel element in the preceding stage of the operational amplifier 15 and the subsequent stage of the terminating voltage follower circuit 16 are provided. By the high-pass filter 8 configured by providing the capacitor 12 as a series element, it is possible to prevent the S / N of the video signal in the low frequency band from approaching a constant value, thereby compensating for the narrow dynamic range of the A / D converter 9 and making it equivalent. Therefore, a wide dynamic range of the input end of the receiver 6 is secured.

Further, even when the clutter / target signal in a short distance is small, the amount of blocking in the low frequency band can be reduced, so that the S / N ratio of the low frequency band video signal can be made constant.

Example 4. FIG. 4 shows a block diagram of an FM-CW radar device in Embodiment 4 of the present invention. In the figure, 1 to 12 are the same as those of a conventional FM-CW radar, 13 is a coil, 14 is a terminating resistor, 15 is an operational amplifier, and 16 is a terminating voltage follower circuit.

Also in this case, similarly to the first embodiment, the operational amplifier 15 and the terminating voltage follower circuit 16 in which the terminating resistor 14 is provided as a parallel element in the preceding stage of the operational amplifier 15 and the subsequent stage of the terminating voltage follower circuit 16 are provided. The capacitor 12 is provided as a series element, and the coil 13 is provided in front of the capacitor 12.
Is provided as a parallel element, it is possible to prevent the S / N of the video signal in the low band from approaching a constant value by the high-pass filter 8, which compensates for the narrow dynamic range of the A / D converter 9, and equivalently A wide dynamic range is secured at the input end of the receiver 6.

Further, as compared with the first embodiment, the termination resistor 14 is not connected to the coil 13, so that the blocking amount in the blocking region can be increased.

Example 5. FIG. 5 shows a block diagram of an FM-CW radar device according to a fifth embodiment of the present invention. In the figure, 1 to 12 are the same as those of a conventional FM-CW radar, 13 is a coil, 14 is a terminating resistor, 15 is an operational amplifier, and 16 is a terminating voltage follower circuit.

Also in this case, similarly to the first embodiment, the operational amplifier 15 and the terminating voltage follower circuit 16 in which the terminating resistor 14 is provided as a parallel element in the preceding stage of the operational amplifier 15 and the subsequent stage of the terminating voltage follower circuit 16 are provided. The high-pass filter 8 configured by providing the capacitor 12 as a series element and providing the coil 13 as a parallel element in the front and rear stages of the capacitor 12 can prevent the S / N of the video signal in the low frequency from approaching a constant value. The narrow dynamic range of the / D converter 9 is compensated, and a wide dynamic range of the input end of the receiving unit 6 is equivalently secured.

Further, even when the clutter / target signal in a short distance is large, the amount of blocking in the low frequency band can be easily increased, so that the S / N of the low frequency band video signal can be brought close to a constant value.

Example 6. FIG. 6 shows a block diagram of an FM-CW radar device according to a sixth embodiment of the present invention. In the figure, 1 to 12 are the same as those of a conventional FM-CW radar, 13 is a coil, 14 is a terminating resistor, 15 is an operational amplifier, 16 is a terminating voltage follower circuit, and 17 is a resistor.

Also in this case, similarly to the first embodiment, the operational amplifier 15 and the terminating voltage follower circuit 16 in which the terminating resistor 14 is provided as a parallel element in the previous stage of the operational amplifier 15 and the subsequent stage of the terminating voltage follower circuit 16 are provided. The capacitor 12 is provided as a series element, and the coil 1 is provided in front of the capacitor 12.
3, the high-pass filter 8 configured by providing a series circuit of the capacitor 12 and the resistor 17 as a parallel element can prevent the S / N of the video signal in the low band from approaching a constant value, and the dynamic of the A / D converter 9 can be prevented. By compensating for the narrow range, the wide dynamic range of the input end of the receiving unit 6 is equivalently secured.

Further, even if clutter occurs in a specific frequency band, the amount of blocking in a specific frequency band can be limited / constant, so that the S / N of a short-distance video signal can be made to be close to a constant value. The S / N of a long-distance video signal does not need to be lowered in a region without high clutter, and the performance is improved.

Example 7. FIG. 7 shows a block diagram of an FM-CW radar device in Embodiment 7 of the present invention. In the figure, 1 to 12 are the same as those of a conventional FM-CW radar, 13 is a coil, 15 is an operational amplifier, and 18 is a voltage follower circuit.

Also in this case, as in the first embodiment, the voltage follower circuit 18 by the operational amplifier 15 and the capacitor 12 as a series element are provided at the subsequent stage of the voltage follower circuit 18 and the coil 13 as a parallel element at the previous stage of the capacitor 12. The S / N of the video signal in the low frequency band can be blocked by the high-pass filter 8 configured to be provided so as to be close to a constant value, and the narrow dynamic range of the A / D converter 9 is compensated for. A wide dynamic range at the input end is secured.

Further, when the output impedance of the mixer 7 is high, the voltage follower circuit 1 including only the operational amplifier 15 is provided.
The impedance matching between the mixer 7 and the high-pass filter 8 can be achieved by the means 8.

Example 8. FIG. 8 shows a block diagram of an FM-CW radar device according to Embodiment 8 of the present invention. In the figure, 1 to 12 are the same as those of the conventional FM-CW radar, 14 is a terminating resistor, 15 is an operational amplifier, and 17 is a resistor.

Also in this case, similarly to the first embodiment, the high pass filter 8 constituted by disposing the terminating resistor 14 as a parallel element in the preceding stage of the active filter including the operational amplifier 15, the resistor 17 and the capacitor 12 allows the low pass filter 8 to operate. The S / N ratio of the video signal at
The narrow dynamic range of the D converter 9 is compensated, and the wide dynamic range of the input end of the receiving unit 6 is equivalently secured.

Further, the active filter can realize the high-pass filter 8 having a high Q with a smaller number of elements than the filter constituted by the combination of the capacitor, the coil and the resistor.
Since it can be partially shared with the video amplifier 9, the receiver 6 can be downsized.

Example 9. FIG. 9 shows a block diagram of an FM-CW radar device in Embodiment 9 of the present invention. In the figure, 1 to 12 are the same as those of a conventional FM-CW radar, 15 is an operational amplifier, and 17 is a resistor.

Also in this case, as in the first embodiment, the S / N ratio of the video signal in the low frequency band is made constant by the high-pass filter 8 composed of the active filter including the operational amplifier 15, the resistor 17 and the capacitor 12. It is possible to prevent this, compensate for the narrow dynamic range of the A / D converter 9, and equivalently secure a wide dynamic range at the input end of the receiving section 6.

Further, a high-pass filter 8 having a high Q can be realized with a smaller number of elements in an active filter than a filter composed of a combination of a capacitor, a coil and a resistor.
Since it can be partially shared with the video amplifier 9, the receiver 6 can be downsized.

Further, when the output impedance of the mixer 7 is high, the impedance matching between the mixer 7 and the high pass filter 8 can be achieved by the active filter.

Example 10. FIG. 10 shows a first embodiment of the present invention.
The block diagram of the FM-CW radar apparatus in 0 is shown.
In the figure, 1-8 and 10-12 are the same as the conventional FM-CW radar, 9a is the first video amplifier,
9b is a second video amplifier.

Next, the operation will be described. In the transmission unit 1, the voltage controlled oscillator 2 receives the modulation signal from the modulator 4 to generate a frequency-modulated high frequency signal, and the directional coupler 3 transmits a part of the high frequency signal to the reception unit 6 as a local oscillation signal. The rest is sent to the first antenna 5a as a transmission signal. The first antenna 5a irradiates the target with the transmission signal, and the second antenna 5b receives the reflection from the target and outputs the reception signal. In the receiving unit 6, the mixer 7 frequency-converts the received signal and outputs a video signal having a beat frequency component corresponding to the target distance / speed, and the second video signal 9b, the high-pass filter 8, and the first pass filter 8 are provided. It is sent to the signal processing unit 11 as a digital signal via the video amplifier 9a and the A / D converter 10. The signal processing unit 11 obtains target distance / speed information by frequency analysis and arithmetic processing of the digital signal. The high-pass filter 8 comprises a capacitor 12 as a series element, and lowers the video clutter level together with the video signal level until the video signal is near the S / N limit in a region where the S / N of the video signal has a margin. That is, the S / N ratio of the video signal in the low frequency band is blocked so as to approach a constant value, the narrow dynamic range of the A / D converter 10 is compensated, and a wide dynamic range of the input end of the receiving unit 6 is equivalently secured. it can.

Further, even if the short range clutter / target signal is small, the amount of blocking in the low frequency band can be reduced, so that the S / N ratio of the low frequency band video signal can be made constant.

Furthermore, by using the second video amplifier 9b in the preceding stage of the high pass filter 8, the N of the receiving section 6 is reduced.
F (noise figure) can be improved.

Example 11. FIG. 11 shows a first embodiment of the present invention.
2 is a block diagram of the FM-CW radar device in FIG.
In the figure, 1-8 and 10-12 are the same as the conventional FM-CW radar, 9a is the first video amplifier,
9b is a second video amplifier, and 13 is a coil.

Also in this case, similarly to the tenth embodiment, the second video amplifier 9b, the capacitor 12 is provided as a series element in the latter stage of the second video amplifier 9b, and the coil 13 is arranged in parallel in the former stage of the capacitor 12. By the high-pass filter 8 provided as an element, it is possible to prevent the S / N of the video signal in the low band from approaching a constant value, and to compensate for the narrow dynamic range of the A / D converter 9, and equivalently to the receiving section. The wide dynamic range of 6 input terminals is secured.

Further, by using the second video amplifier 9b in the preceding stage of the high pass filter 8, the N of the receiving section 6 is reduced.
F can be improved.

Example 12 FIG. 12 shows the first embodiment of the present invention.
2 is a block diagram of the FM-CW radar device in FIG.
In the figure, 1-8 and 10-12 are the same as the conventional FM-CW radar, 9a is the first video amplifier,
9b is a second video amplifier, and 13 is a coil.

Also in this case, as in the tenth embodiment, the second video amplifier 9b and the capacitor 12 are provided as a series element, and a coil is provided as a parallel element before and after the capacitor 12 to form a high-pass filter. By the filter 8,
It is possible to prevent the S / N of the video signal in the low frequency range from approaching a constant value, to compensate for the narrow dynamic range of the A / D converter 9, and equivalently to secure a wide dynamic range at the input end of the receiving section 6. .

Further, even if the clutter / target signal at a short distance is large, the amount of blocking in the low frequency band can be easily increased, so that the S / N ratio of the low frequency band video signal can be brought close to a constant value.

Further, by using the second video amplifier 9b in the preceding stage of the high pass filter 8, the N of the receiving unit 6 is
F can be improved.

Example 13 FIG. 13 shows a first embodiment of the present invention.
3 is a block diagram of the FM-CW radar device in FIG.
In the figure, 1-8 and 10-12 are the same as the conventional FM-CW radar, 9a is the first video amplifier,
9b is a second video amplifier, 13 is a coil, and 17 is a resistor.

Also in this case, as in the tenth embodiment, the second video amplifier 9b and the capacitor 12 are connected in series, and the coil 13 and the capacitor 1 are provided in front of the capacitor 12.
By the high-pass filter 8 configured by providing a series circuit of 2 and the resistor 17 as a parallel element, it is possible to prevent the S / N of the video signal in the low band from approaching a constant value, and the narrow dynamic range of the A / D converter 9. To compensate for this, a wide dynamic range is equivalently secured at the input end of the receiver 6.

Further, even if clutter occurs in a specific frequency band, the amount of blocking in a specific frequency band can be limited / constant, so that the S / N of a short-distance video signal can be made to be close to a constant value. The S / N of a long-distance video signal does not need to be lowered in a region without high clutter, and the performance is improved.

Further, by using the second video amplifier 9b in the preceding stage of the high pass filter 8, the N of the receiving section 6 is
F can be improved.

Example 14 FIG. 14 shows a first embodiment of the present invention.
4 is a block diagram of the FM-CW radar device in FIG.
In the figure, 1 to 12 are the same as the conventional FM-CW radar, 13 is a coil, 14 is a terminating resistor, and 19 is a resistor.
Is a low pass filter.

Next, the operation will be described. In the transmission unit 1, the voltage controlled oscillator 2 receives the modulation signal from the modulator 4 to generate a frequency-modulated high frequency signal, and the directional coupler 3 transmits a part of the high frequency signal to the reception unit 6 as a local oscillation signal. The rest is sent to the first antenna 5a as a transmission signal. The first antenna 5a irradiates the target with the transmission signal, and the second antenna 5b receives the reflection from the target and outputs the reception signal. In the receiving unit 6, the mixer 7 frequency-converts the received signal and outputs a video signal having a beat frequency component corresponding to the target distance / speed, and the low-pass filter 19, high-pass filter 8, and video amplifier 9 are provided. Also, it is sent to the signal processing unit 11 as a digital signal via the A / D converter 10. The signal processing unit 11 obtains target distance / speed information by frequency analysis and arithmetic processing of the digital signal. The low-pass filter 19 uses the coil 13 as a series element,
, A series circuit of a capacitor 12 and a terminating resistor 14 is provided as a parallel element in the preceding stage, and a capacitor 1 is provided in the subsequent stage of the coil 13.
2 is provided as a parallel element to suppress leakage components of the received signal from the mixer 7 and the local oscillation signal. The high-pass filter 8 is configured by using the capacitor 12 as a series element and providing the series circuit of the coil 13 and the terminating resistor 14 as a parallel element in the preceding stage of the capacitor 12 in a region where there is a margin in S / N of the video signal. , The video clutter level is lowered together with the video signal level until the video signal is close to the S / N limit, that is, the S / N of the video signal in the low frequency band is prevented from approaching a constant level, and the dynamic of the A / D converter 10 is reduced. It is possible to compensate for the narrow range and equivalently secure a wide dynamic range at the input end of the receiving unit 6.

Example 15. FIG. 15 shows a first embodiment of the present invention.
5 is a block diagram of the FM-CW radar device in FIG.
In the figure, 1 to 12 are the same as the conventional FM-CW radar, 13 is a coil, 14 is a terminating resistor, and 15 is a resistor.
Is an operational amplifier, 17 is a resistor, and 19 is a low-pass filter.

Also in this case, similarly to the fourteenth embodiment, the low-pass filter 19 and the capacitor 12 which are formed by providing the terminating resistor 14 as a parallel element in the preceding stage of the active filter including the operational amplifier 15, the resistor 17, and the capacitor 12.
Is a serial element, and the coil 13 is provided as a parallel element in the preceding stage of the capacitor 12, so that the S / N ratio of the video signal in the low frequency band can be prevented from approaching a constant level by the high pass filter 8, and the A / D converter 9 By compensating for the narrow dynamic range, the equivalent wide dynamic range is secured at the input end of the receiver 6.

Further, as compared with the fourteenth embodiment, the coil 13
Since the terminating resistor 14 is not connected to, it is possible to increase the blocking amount in the blocking region.

Example 16. FIG. 16 shows a first embodiment of the present invention.
6 is a block diagram of the FM-CW radar device in FIG.
In the figure, 1 to 12 are the same as the conventional FM-CW radar, 13 is a coil, 15 is an operational amplifier, 17
Is a resistor, and 19 is a low-pass filter.

Also in this case, similarly to the fourteenth embodiment, the low-pass filter 19 constituted by the active filter including the operational amplifier 15, the resistor 17 and the capacitor 12, and the capacitor 12 are series elements, and the coil 13 is provided in the preceding stage of the capacitor 12. Is provided as a parallel element, it is possible to prevent the S / N of the video signal in the low band from approaching a constant value by the high-pass filter 8, which compensates for the narrow dynamic range of the A / D converter 9, and equivalently A wide dynamic range is secured at the input end of the receiver 6.

Further, when the output impedance of the mixer 7 is high, the impedance matching between the mixer 7 and the high pass filter 8 can be achieved by the active filter.

Example 17 FIG. 17 shows a first embodiment of the present invention.
7 is a block diagram of the FM-CW radar device in FIG.
In the figure, 1-8 and 10-12 are the same as the conventional FM-CW radar, 9a is the first video amplifier,
Reference numeral 9b is a second video amplifier, 13 is a coil, 14 is a terminating resistor, and 19 is a low-pass filter.

Next, the operation will be described. In the transmission unit 1, the voltage controlled oscillator 2 receives the modulation signal from the modulator 4 to generate a frequency-modulated high frequency signal, and the directional coupler 3 transmits a part of the high frequency signal to the reception unit 6 as a local oscillation signal. The rest is sent to the first antenna 5a as a transmission signal. The first antenna 5a irradiates the target with the transmission signal, and the second antenna 5b receives the reflection from the target and outputs the reception signal. In the receiving unit 6, the mixer 7 frequency-converts the received signal and outputs a video signal having a beat frequency component according to the target distance and speed, and outputs the second video signal 9b, the low-pass filter 19, and the high-pass filter. It is sent to the signal processing unit 11 as a digital signal via the pass filter 8, the first video amplifier 9 a and the A / D converter 10. The signal processing unit 11 obtains target distance / speed information by frequency analysis and arithmetic processing of the digital signal. The low-pass filter 19 uses the coil 13 as a series element, and the capacitor 1 is provided in front of the coil 13.
2 and a terminating resistor 14 are connected in series as a parallel circuit,
The capacitor 12 is provided as a parallel element in the subsequent stage of the coil 13 to suppress the leakage component of the received signal from the mixer 7 and the local oscillation signal. The high-pass filter 8 has a capacitor 12 as a series element, and the coil 1 is provided in front of the capacitor 12.
3 is provided as a parallel element to configure the S / N of the video signal.
The video clutter level is lowered together with the video signal level until the video signal is close to the S / N limit, that is, the S / N of the video signal in the low frequency range.
Is prevented from approaching to a constant value, the narrow dynamic range of the A / D converter 10 is compensated, and a wide dynamic range of the input end of the receiving unit 6 is equivalently secured.

Furthermore, by using the second video amplifier 9b in the preceding stage of the high pass filter 8, the N of the receiving section 6 is
F can be improved.

Example 18. FIG. 18 shows a first embodiment of the present invention.
8 is a block diagram of the FM-CW radar device in FIG.
In the figure, 1-8 and 10-12 are the same as the conventional FM-CW radar, 9a is the first video amplifier,
9b is a second video amplifier, 13 is a coil, 14 is a terminating resistor, 15 is an operational amplifier, 17 is a resistor, and 19 is a low-pass filter.

Also in this case, as in the seventeenth embodiment, the low-pass filter 19 having the terminating resistor 14 as a parallel element in the preceding stage of the active filter including the operational amplifier 15, the resistor 17, and the capacitor 12, and the second filter The high-pass filter 8 configured by connecting the video amplifier 9B and the capacitor 12 in series as elements and the coil 13 as a parallel element in front of the capacitor 12 prevents the S / N of the video signal in the low frequency from approaching a constant value. Therefore, the narrow dynamic range of the A / D converter 9 is compensated, and the wide dynamic range of the input end of the receiver 6 is equivalently secured.

Further, by using the second video amplifier 9b in the preceding stage of the high pass filter 8, the N of the receiving section 6 is
F can be improved.

Example 19. FIG. 19 shows a first embodiment of the present invention.
9 is a block diagram of the FM-CW radar device in FIG.
In the figure, 1-8 and 10-12 are the same as the conventional FM-CW radar, 9a is the first video amplifier,
9b is a second video amplifier, 13 is a coil, 15 is an operational amplifier, 17 is a resistor, and 19 is a low-pass filter.

Also in this case, as in the seventeenth embodiment, the low-pass filter 19 constituted by the active filter including the operational amplifier 15, the resistor 17 and the capacitor 12, the second video amplifier 9b and the capacitor 12 are connected in series. ,
The S / N of the video signal in the low frequency band can be prevented from approaching a constant value by the high-pass filter 8 configured by providing the coil 13 as a parallel element in the preceding stage of the capacitor 12,
The narrow dynamic range of the / D converter 9 is compensated, and a wide dynamic range of the input end of the receiving unit 6 is equivalently secured.

Further, by using the second video amplifier 9b in the preceding stage of the high pass filter 8, the N of the receiving section 6 is reduced.
F can be improved.

Further, when the output impedance of the mixer 7 is high, the impedance matching between the mixer 7 and the high pass filter 8 can be achieved by the active filter.

Although the case where two antennas are used and each is used for transmission and reception has been described above, the same effect can be obtained when one antenna is used for both transmission and reception.

[0107]

According to the first embodiment of the present invention, the mixer 7
And a video amplifier 9, a capacitor 12 is used as a series element and a coil 13 and a terminating resistor 14 are provided in front of the capacitor 12.
Is provided with a series circuit as a parallel element, and the stop band of the high pass filter 8 is overlapped with the frequency band of the video signal so that the S /
In an area where N is available, the video clutter level is lowered together with the video signal level until the video signal is close to the S / N limit, and the S / N of the video signal is approximated to a constant value. The narrow dynamic range of the instrument 10 is compensated for, and the dynamic range of the input end of the receiving section 6 can be secured equivalently, and the configuration is simple, and the cost and performance are high.

According to the second embodiment of the present invention, the capacitor 12 is connected in series between the mixer 7 and the video amplifier 9, and the coil 13 and the terminating resistor 1 are provided in the preceding stage of the capacitor 12.
4 is provided as a parallel element, and the high pass filter 8 is configured by providing the coil 13 as a parallel element after the capacitor 12 to reduce the level of the video clutter and the video signal to reduce the S / N ratio of the video signal. Can be close to a constant value.

According to the third embodiment of the present invention, the operational amplifier 15 and the operational amplifier 1 are provided between the mixer 7 and the video amplifier 9.
5, a termination type voltage follower circuit 16 in which a termination resistor 14 is provided as a parallel element in the preceding stage, and a termination type voltage follower circuit 1
Since the high-pass filter 8 configured by providing the capacitor 12 as a series element in the subsequent stage of 6 is provided to reduce the blocking amount in the low frequency range, even if the clutter / target signal in a short distance is small, It is possible to bring the S / N of the video signal in the range close to a constant value.

According to the fourth embodiment of the present invention, the operational amplifier 15 and the operational amplifier 1 are provided between the mixer 7 and the video amplifier 9.
5, a termination type voltage follower circuit 16 in which a termination resistor 14 is provided as a parallel element in the preceding stage, and a termination type voltage follower circuit 1
6 is provided with a capacitor 12 as a serial element in the subsequent stage and a coil 13 is provided in the preceding stage of the capacitor 12 as a parallel element, and is provided with a high-pass filter 8 for reducing the level of the video clutter and the video signal, and reducing the S of the video signal. / N can be made constant.

According to the fifth embodiment of the present invention, the operational amplifier 15 and the operational amplifier 1 are provided between the mixer 7 and the video amplifier 9.
5, a termination type voltage follower circuit 16 in which a termination resistor 14 is provided as a parallel element in the preceding stage, and a termination type voltage follower circuit 1
6 is provided with a capacitor 12 as a serial element, and a high-pass filter 8 configured by providing a coil 13 as a parallel element at the preceding and subsequent stages of the capacitor 12 to reduce the level of the video clutter and the video signal. The S / N of can be brought close to a constant value.

According to the sixth embodiment of the present invention, the terminating voltage follower circuit 16 in which the terminating resistor 14 is provided as a parallel element between the mixer and the video amplifier and the terminating resistor 14 is provided in front of the operational amplifier 15, and the terminating voltage follower circuit 16 are provided. The capacitor 12 is provided as a series element in the subsequent stage of the follower circuit 16, and the coil 13, the capacitor 12, and the resistor 1 are provided in the preceding stage of the capacitor 12.
Since a high-pass filter configured by disposing the serial circuit of 7 as a parallel element is provided to limit / constant the blocking amount in a specific frequency band, even if clutter occurs in a specific frequency band, a close range The S / N ratio of the long distance video signal is kept close to a certain level, and the S / N ratio of the long distance video signal does not have to be lowered in a high frequency area where there is no clutter, and the performance is improved.

According to the seventh embodiment of the present invention, the voltage follower circuit 18 by the operational amplifier 15 is provided between the mixer 7 and the video amplifier 9, and the capacitor 12 is provided as a series element at the subsequent stage of the voltage follower circuit 18. The high-pass filter 8 configured by providing the coil 13 as a parallel element in the preceding stage can reduce the levels of the video clutter and the video signal to bring the S / N of the video signal close to a constant level. When the output impedance is high, the impedance matching between the mixer 7 and the high pass filter 8 can be achieved.

According to the eighth embodiment of the present invention, the terminating resistor 14 is provided as a parallel element between the mixer 7 and the video amplifier 9 in the preceding stage of the active filter including the operational amplifier 15, the resistor 17 and the capacitor 12. A high pass filter 8 having a high Q with a small number of elements is provided, which can reduce the levels of the video clutter and the video signal and bring the S / N of the video signal close to a constant level by including the high pass filter 8. Since it can be partially shared with the receiver 9, the receiver 6 can be downsized.

According to the ninth embodiment of the present invention, the high-pass filter 8 constituted by the active filter including the operational amplifier 15, the resistor 17 and the capacitor 12 is provided between the mixer 7 and the video amplifier 9, and the video clutter and the video signal are provided. Can be lowered to make the S / N ratio of the video signal close to a constant value. Further, when the output impedance of the mixer 7 is high, the impedance matching between the mixer 7 and the high-pass filter 8 can be achieved. Since the high-pass filter 8 having a high Q can be realized with a small number of elements and can be partially shared with the video amplifier 9, the receiver 6 can be downsized.

According to the tenth embodiment of the present invention, the mixer 7
Since the second video amplifier 9b and the high-pass filter 8 having the capacitor 12 as a series element are provided between the first video amplifier 9a and the first video amplifier 9a, the amount of blocking in the low frequency band is reduced. Even if the short-distance clutter / target signal is small, the S / N ratio of the low-frequency video signal can be brought close to a constant value, and the second video amplifier 9b is used in the preceding stage of the high-pass filter 8. Therefore, the NF of the receiving unit 6
Can be improved.

According to the eleventh embodiment of the present invention, the mixer 7
Between the first video amplifier 9a and the second video amplifier 9b, and the capacitor 12 as a series element,
A high-pass filter 8 having a coil 13 as a parallel element is provided in the preceding stage of 2, so that the levels of the video clutter and the video signal can be lowered, and the S / N of the video signal can be brought close to a constant level. Since the second video amplifier 9b is used before the high-pass filter 8, the receiving unit 6
Can improve the NF.

According to the twelfth embodiment of the present invention, the mixer 7
Between the first video amplifier 9a and the second video amplifier 9b, and the capacitor 12 as a series element,
A high-pass filter having a coil provided as a parallel element in the front stage and the rear stage of 2 can be provided to reduce the levels of the video clutter and the video signal and to bring the S / N of the video signal close to a constant level. Since the second video amplifier 9b is used in the preceding stage of the high pass filter 8, the NF of the receiving section 6 can be improved.

According to the thirteenth embodiment of the present invention, the mixer 7
Between the first video amplifier 9a and the second video amplifier 9b, and the capacitor 12 as a series element,
2 is provided with a high-pass filter that is configured by providing a series circuit of a coil 13, a capacitor 12, and a resistor 17 as a parallel element in the preceding stage of 2, and is configured to limit / constant the blocking amount of a specific frequency band. Even if the clutter occurs in the frequency band of, the S / N of the video signal at a short distance is kept close to a certain level, and the S / N of the video signal at a long distance does not have to be reduced in the high frequency area where there is no clutter. Since the second video signal 9b is used before the high pass filter 8, the NF of the receiver 6 can be improved. .

According to the fourteenth embodiment of the present invention, the mixer 7
And the video amplifier 9 between the coil 13 as a series element,
A low-pass filter 19 configured by providing a series circuit of a capacitor 12 and a terminating resistor 14 as a parallel element in a front stage of the coil 13 and a capacitor 12 in a rear stage of the coil 13 and a capacitor 12 as a series element, A high-pass filter 8 is provided in which a series circuit of a coil 13 and a terminating resistor 14 is provided as a parallel element in the preceding stage of the capacitor 12 to reduce the level of the video clutter and the video signal and keep the S / N of the video signal constant. Can be approached to.

According to the fifteenth embodiment of the present invention, the mixer 7
Between the operational amplifier 15, the resistor 17, and the capacitor 12, a low-pass filter 19 configured by providing a terminating resistor 14 as a parallel element between the operational amplifier 15, the resistor 17, and the capacitor 12, and the capacitor 12 as a series element. A high-pass filter 8 having a coil 13 as a parallel element is provided in the preceding stage, so that the levels of the video clutter and the video signal can be lowered and the S / N of the video signal can be brought close to a constant level.

According to the sixteenth embodiment of the present invention, the mixer 7
And a video amplifier 9, an operational amplifier 15, a resistor 17, and a low-pass filter 19 composed of an active filter composed of a capacitor 12 and a capacitor 12 are connected in series, and a coil 13 is arranged in parallel with the capacitor 12 in the preceding stage of the capacitor 12. If the output impedance of the mixer 7 is high, the mixer 7 and the high-pass filter 8 can reduce the levels of the video clutter and the video signal to bring the S / N of the video signal close to a constant level. The impedance of the pass filter 8 can be matched.

According to the seventeenth embodiment of the present invention, the mixer 7
Between the first video amplifier 9a and the first video amplifier 9a, the coil 13 is used as a serial element, the series circuit of the capacitor 12 and the terminating resistor 14 is provided as a parallel element in the front stage of the coil 13, and the capacitor 12 is used as a parallel element in the rear stage of the coil 13. A low-pass filter 9 provided and configured, a second video amplifier 9b, and a capacitor 12 as a series element, and a high-pass filter configured by providing a coil 13 as a parallel element before the capacitor 12 are provided. It is possible to lower the level of the video signal and bring the S / N of the video signal close to a constant value. Further, since the second video amplifier 9b is used in the preceding stage of the high pass filter 8, The NF can be improved.

According to the eighteenth embodiment of the present invention, the mixer 7
Between the first video amplifier 9a and the first video amplifier 9a, the low-pass filter 19 constituted by arranging the terminating resistor 14 as a parallel element before the active filter including the operational amplifier 15, the resistor 17, and the capacitor 12, and the second video amplifier 9b. And a high-pass filter 8 having a capacitor 12 as a serial element and a coil 13 as a parallel element in the preceding stage of the capacitor 12 to reduce the level of the video clutter and the video signal to reduce the S / N of the video signal. The second video amplifier 9b is used before the high-pass filter 8 so that the NF of the receiving unit 6 can be improved.

According to the nineteenth embodiment of the present invention, the mixer 7
Between the first video amplifier 9a and the first video amplifier 9a, a low-pass filter 19 composed of an active filter including a resistor 17 and a capacitor 12, and a second video amplifier 9a.
b and the capacitor 12 as a series element, the capacitor 12
Is provided with a high-pass filter 8 having a coil 13 as a parallel element in the preceding stage thereof, the level of the video clutter and the video signal can be lowered, and the S / N of the video signal can be brought close to a constant level. Since the video amplifier 9b is used in the preceding stage of the high-pass filter 8, the NF of the receiving unit 6 can be improved. Further, when the output impedance of the mixer 7 is high, the mixer 7 and the high-pass filter 8 are
The impedance matching can be achieved.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an FM-CW radar according to a first embodiment of the present invention.

FIG. 2 is a configuration block diagram of an FM-CW radar according to a second embodiment of the present invention.

FIG. 3 is a configuration block diagram of an FM-CW radar according to a third embodiment of the present invention.

FIG. 4 is a configuration block diagram of an FM-CW radar according to Embodiment 4 of the present invention.

FIG. 5 is a configuration block diagram of an FM-CW radar according to a fifth embodiment of the present invention.

FIG. 6 is a configuration block diagram of an FM-CW radar according to a sixth embodiment of the present invention.

FIG. 7 is a configuration block diagram of an FM-CW radar according to a seventh embodiment of the present invention.

FIG. 8 is a configuration block diagram of an FM-CW radar according to Embodiment 8 of the present invention.

FIG. 9 is a configuration block diagram of an FM-CW radar according to a ninth embodiment of the present invention.

FIG. 10 is a configuration block diagram of an FM-CW radar according to Embodiment 10 of the present invention.

FIG. 11 is a configuration block diagram of an FM-CW radar according to Embodiment 11 of the present invention.

FIG. 12 is a configuration block diagram of an FM-CW radar according to a twelfth embodiment of the present invention.

FIG. 13 is a configuration block diagram of an FM-CW radar according to Embodiment 13 of the present invention.

FIG. 14 is a configuration block diagram of an FM-CW radar according to Embodiment 14 of the present invention.

FIG. 15 is a configuration block diagram of an FM-CW radar according to Embodiment 15 of the present invention.

FIG. 16 is a configuration block diagram of an FM-CW radar according to Embodiment 16 of the present invention.

FIG. 17 is a configuration block diagram of an FM-CW radar according to Embodiment 17 of the present invention.

FIG. 18 is a configuration block diagram of an FM-CW radar according to Embodiment 18 of the present invention.

FIG. 19 is a configuration block diagram of an FM-CW radar according to Embodiment 19 of the present invention.

FIG. 20 is a configuration block diagram of a conventional FM-CW radar.

FIG. 21 is a diagram showing a principle of operation of a conventional FM-CW radar.

FIG. 22 is a diagram showing a reception level of a conventional FM-CW radar.

FIG. 23 is a diagram showing an FM-CW level reception level according to the first embodiment of the present invention.

[Explanation of symbols]

1 transmitter, 2 voltage controlled oscillator, 3 directional coupler,
4 modulator, 5a first antenna, 5b second antenna, 6 receiving section, 7 mixer, 8 high pass filter, 9 video amplifier, 10 A / D converter, 11 signal processing section, 12 capacitor, 13 coil , 14 termination resistor, 15 operational amplifier, 16 termination type voltage follower circuit, 17 resistor, 18 voltage follower circuit, 19 low pass filter.

Claims (19)

[Claims] 1. A first antenna for irradiating a target with a transmission signal, a modulator, a voltage controlled oscillator for generating a high frequency signal frequency-modulated by a modulation signal output from the modulator, and this voltage. Directional coupler for outputting a part of the high frequency signal output from the controlled oscillator to the first antenna as a transmission signal and the rest as a transmission signal, and a second antenna for receiving a reception signal from a target. A mixer for frequency-converting the received signal from the second antenna using the local oscillation signal output from the directional coupler, and a mixer connected to an intermediate frequency output end of the mixer, with a capacitor as a series element. , A high-pass filter configured by connecting a series circuit of a coil and a terminating resistor as a parallel element in the preceding stage of this capacitor, and a video amplifier that amplifies the output signal of this high-pass filter. The above-mentioned high-pass filter is provided with a width device, an A / D converter for converting the output signal of the video amplifier into a digital signal, and a signal processing unit for frequency-analyzing the digital signal to obtain target distance / speed information. An FM-CW radar characterized in that a stop band of a filter is overlapped with a frequency band of a video signal. 2. The high-pass filter comprises a capacitor as a series element, a series circuit of a coil and a terminating resistor as a parallel element before the capacitor, and a coil as a parallel element after the capacitor. The FM-CW radar according to claim 1, wherein 3. A high-pass filter, a termination type voltage follower circuit in which a termination resistor is provided as a parallel element in a stage before the operational amplifier and the operational amplifier, and a capacitor is provided as a series element in a stage subsequent to the termination type voltage follower circuit. The FM-CW radar according to claim 1, wherein the FM-CW radar is configured. 4. A high-pass filter, wherein an operational amplifier and a terminating voltage follower circuit in which a terminating resistor is provided as a parallel element in the preceding stage of the operational amplifier, and a capacitor as a series element in the subsequent stage of the terminating voltage follower circuit are provided. 2. The FM-CW radar according to claim 1, wherein a coil is provided as a parallel element in the preceding stage of the capacitor. 5. The high-pass filter is provided with an operational amplifier and a terminating voltage follower circuit in which a terminating resistor is provided as a parallel element in the preceding stage of the operational amplifier, and a capacitor is provided as a series element in the subsequent stage of the terminating type voltage follower circuit. 2. The FM-C according to claim 1, wherein a coil is provided as a parallel element in a front stage and a rear stage of the capacitor.
W radar. 6. A high-pass filter, a termination type voltage follower circuit having an operational amplifier and a termination resistor provided as a parallel element in a stage before the operational amplifier, and a capacitor provided as a series element in a stage subsequent to the termination type voltage follower circuit. The FM-CW radar according to claim 1, wherein a series circuit of a coil, a capacitor, and a resistor is provided as a parallel element in the preceding stage of the capacitor. 7. The high-pass filter comprises a voltage follower circuit using an operational amplifier, a capacitor provided as a series element in the latter stage of the voltage follower circuit, and a coil provided as a parallel element in the former stage of the capacitor. The FM-CW radar according to claim 1. 8. The FM-CW radar according to claim 1, wherein the high-pass filter is configured by arranging a terminating resistor as a parallel element in front of an active filter including an operational amplifier, a resistor and a capacitor. 9. The FM-CW radar according to claim 1, wherein the high-pass filter comprises an active filter including an operational amplifier, a resistor and a capacitor. 10. A first antenna for irradiating a target with a transmission signal, a modulator, a voltage controlled oscillator for generating a high frequency signal frequency-modulated by a modulation signal output from the modulator, and this voltage. Directional coupler for outputting a part of the high frequency signal output from the controlled oscillator to the first antenna as a transmission signal and the rest as a transmission signal, and a second antenna for receiving a reception signal from a target. A mixer that frequency-converts the received signal from the second antenna using the local oscillation signal output from the directional coupler, a second video amplifier that amplifies the output signal of the mixer, and Connected to the output of the second video amplifier,
A high-pass filter including a capacitor as a series element, a first video amplifier for amplifying an output signal of the high-pass filter, and an A / D for converting the output signal of the first video amplifier into a digital signal. A converter and a signal processing unit for frequency-analyzing the digital signal to obtain target distance / speed information, and the stop band of the high-pass filter overlaps the frequency band of the video signal. FM-CW radar. 11. The high-pass filter according to claim 10, wherein the capacitor is a serial element and the coil is provided as a parallel element before the capacitor.
The described FM-CW radar. 12. The FM-CW radar according to claim 10, wherein the high-pass filter comprises a capacitor as a series element, and a coil as a parallel element at a stage before and after the capacitor. 13. The FM according to claim 10, wherein the high-pass filter comprises a capacitor as a series element and a series circuit of a coil, a capacitor and a resistor provided as a parallel element before the capacitor. -CW radar. 14. A first antenna for irradiating a target with a transmission signal, a modulator, a voltage controlled oscillator for generating a high frequency signal frequency-modulated by a modulation signal output from the modulator, and this voltage. Directional coupler for outputting a part of the high frequency signal output from the controlled oscillator to the first antenna as a transmission signal and the rest as a transmission signal, and a second antenna for receiving a reception signal from a target. A mixer for frequency-converting a received signal from the second antenna using the local oscillation signal output from the directional coupler, and a mixer connected to an intermediate frequency output end of the mixer, with a coil as a series element. , A series circuit of a capacitor and a terminating resistor is provided as a parallel element in the front stage of this coil, and a capacitor is provided as a parallel element in the rear stage of this coil. A low-pass filter whose pass band is the pass band, and a capacitor connected in series connected to the output end of this low-pass filter, and a series circuit of a coil and a terminating resistor is provided in parallel in the preceding stage of this capacitor. High-pass filter, a video amplifier for amplifying the output signal of the high-pass filter, an A / D converter for converting the output signal of the video amplifier into a digital signal, and a frequency analysis of the digital signal for a target distance. An FM-CW radar including a signal processing unit for obtaining speed information, wherein the stop band of the high pass filter overlaps the frequency band of the video signal. 15. The low-pass filter is configured by providing a terminating resistor as a parallel element in front of an active filter including an operational amplifier, a resistor and a capacitor, and the high-pass filter is configured by using a capacitor as a series element and the capacitor as a capacitor. 15. The FM-CW radar according to claim 14, wherein a coil is provided as a parallel element in the preceding stage. 16. The low-pass filter is configured by an active filter including an operational amplifier, a resistor, and a capacitor, and the high-pass filter is configured by using a capacitor as a series element and a coil as a parallel element before the capacitor. 15. The FM- according to claim 14, characterized in that
CW radar. 17. A first antenna for irradiating a target with a transmission signal, a modulator, a voltage controlled oscillator for generating a high frequency signal frequency-modulated by a modulation signal output from the modulator, and this voltage. Directional coupler for outputting a part of the high frequency signal output from the controlled oscillator to the first antenna as a local oscillation signal and the rest as a transmission signal, and a second antenna for receiving a reception signal from a target. A mixer that frequency-converts the received signal from the second antenna using the local oscillation signal output from the directional coupler, a second video amplifier that amplifies the output signal of the mixer, and Connected to the output of the second video amplifier,
A coil is used as a series element, a series circuit of a capacitor and a terminating resistor is provided as a parallel element in the preceding stage of this coil, and a capacitor is provided as a parallel element in the subsequent stage of this coil, and the frequency band of the video signal is used as the pass band. A low-pass filter, a second video amplifier that amplifies the output signal of this low-pass filter, and a capacitor connected in series connected to the output terminal of this second video amplifier, and a coil in front of this capacitor. A high-pass filter provided as a parallel element, a first video amplifier for amplifying the output signal of the high-pass filter, and an A / D converter for converting the output signal of the first video amplifier into a digital signal. When,
An FM-, comprising: a signal processing unit for frequency-analyzing the digital signal to obtain target distance / velocity information, wherein the stop band of the high-pass filter overlaps the frequency band of the video signal. CW radar. 18. The FM-CW radar according to claim 17, wherein the low-pass filter is constituted by arranging a terminating resistor as a parallel element in front of an active filter including an operational amplifier, a resistor and a capacitor. 19. The FM-CW radar according to claim 17, wherein the low-pass filter is composed of an active filter including an operational amplifier, a resistor and a capacitor.