Communications: directive radio wave systems and devices (e.g. – Return signal controls external device – Radar mounted on and controls land vehicle
Reexamination Certificate
2002-03-28
2003-09-02
Tarcza, Thomas H. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Return signal controls external device
Radar mounted on and controls land vehicle
C342S104000, C342S194000, C342S195000, C342S118000, C342S145000
Reexamination Certificate
active
06614390
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for generating and analyzing radar pulses, in particular for short-range pulse radar applications in motor vehicles.
BACKGROUND INFORMATION
In automotive engineering, radar sensors are used to measure the distance to objects and/or the relative speed of such objects outside the motor vehicle. Objects may include, for example, motor vehicles driving ahead or parked motor vehicles, pedestrians, cyclists, or installations in the vicinity of the motor vehicle.
FIG. 1
shows a schematic representation of a radar device with the correlation receiver of the related art. A transmitter
300
is induced by a pulse generator
302
to emit a transmit signal
306
via an antenna
304
. Transmit signal
306
strikes a target object
308
, where it is reflected. Receive signal
310
is received by antenna
312
. This antenna
312
may be identical to antenna
304
. After receive signal
310
is received via antenna
312
, it is transmitted to receiver
314
and is subsequently supplied to a signal analyzer
318
via a unit
316
having a lowpass and an analog/digital converter. The characteristic feature of a correlation receiver is that receiver
314
receives a reference signal
320
from pulse generator
302
. Receive signals
310
received by receiver
314
are mixed with reference signal
320
in receiver
314
. By correlation, it is possible to infer, for example, the distance to a target object on the basis of the time delay between transmission and reception of the radar pulses.
A similar radar device is described in German Published Patent Application No. 199 26 787. A transmission switch is switched on and off by the pulses of a generator so that during the pulse duration, a radio frequency wave generated by an oscillator and guided to the transmission switch via a branching is switched through to the transmitting antenna. A receiving component also receives the output signal of the generator. The receive signal, i.e., a radar pulse reflected by an object, is mixed with the oscillator signal which reaches a mixer via a receive switch during a pre-set time. U.S. Pat. No. 6,067,040 also operates with a transmission switch that is switched on and off by pulses of a generator. For the reception of the reflected radar pulses, separate channels for 1 and Q signals are provided. In this case also, the receive signal is mixed and analyzed only during a pre-set time.
SUMMARY OF THE INVENTION
The measures of the present invention make it possible to detect objects reliably. In contrast to the devices and methods known heretofore, noise problems play only a minor role. In addition, some RF components such as radio frequency switches are eliminated, permitting a simpler, less costly and consequently more cost-effective implementation of a radar sensor.
The present invention makes a radar concept possible which shifts to the LF or IF side the required rapid switching in the range of several hundred ps to detect objects in the vicinity of a motor vehicle, the switching occurring on the RF side in conventional SRR (short range radar). It is possible to combine the mixing and switching function in one component.
The concept according to the present invention requires only one antenna, which is used to transmit and receive radar pulses simultaneously. This essentially reduces the sensor size. In the method according to the present invention, a continuous signal of a radio frequency source may be connected with an antenna via at least one mixer. To generate a radar pulse, the mixer is briefly brought into a state of low throughput loss. The signal of the radio frequency source is then able to pass the mixer and reaches the antenna. Immediately after the radar pulse is generated and transmitted, the mixer is switched over to receive mode and awaits the return of the transmitted radar pulse which is reflected by an object. The delay time is a measure of the distance of the object. Upon receiving the radar pulse, the mixer, together with the continuous signal of the radio frequency source, generates an LF or IF pulse representing the envelope of the RF pulse and is capable of being analyzed.
With the present invention, it is possible to increase the detection range of a radar sensor at a working frequency of 24.125 Ghz to as much as 100 meters since the receive signals of the objects to be detected are not lost in noise as a function of the object characteristics as is ordinarily the case. This makes it possible to detect objects reliably.
In order to attain I/Q capability of the radar, two mixers may be interconnected for the inphase (I)-IF signal and the quadrature (Q)-IF signal.
The mixer or mixers may be placed into the state of low throughput loss, so that the intermediate frequency output of the mixer or mixers is connected to a power source. The resulting mixed signal—IF output signal of the mixer—may be amplified and sampled at a high bandwidth.
The mixed signal may be amplified and scanned separately for the I and Q IF signal.
To sample the mixed signal, a very short sampling pulse may be applied to a broadband sampler, the time of which corresponds to a selected distance cell.
REFERENCES:
patent: 3939341 (1976-02-01), Graves
patent: 4065768 (1977-12-01), Kondoh et al.
patent: 4103301 (1978-07-01), Evans
patent: 5115242 (1992-05-01), Nagamune et al.
patent: 5469167 (1995-11-01), Polge et al.
patent: 5963163 (1999-10-01), Kemkemian et al.
patent: 6067040 (2000-05-01), Puglia
patent: 6087972 (2000-07-01), Puglia et al.
patent: 6362777 (2002-03-01), Kawakami et al.
patent: 199 26 787 (2001-01-01), None
patent: 0 685 930 (1995-12-01), None
Heinz J. Siweris et al., Low-cost GaAs pHEMT MMIC'for millimeter-wave sensor applications, Microwave Theory and Techniques, IEEE Transactions on , vol: 46 Issue: 12 , Dec. 1998, pp: 2560-2567.*
G. Prescott et al., MMIC-based FM-CW radar for multipolarization backscatter measurements, Geoscience and Remote Sensing Symposium, 1995, ‘Quantitative Remote Sensing for Science and Applications’, International , vol: 3, pp: 2273-2275.*
Villemazet et al. , MMIC couble-balanced mixer, Villemazet et al. , Nov. 29, 2001, patent application Publication U.S.-2001/0046849 A1.
Alsomiri Isam
Kenyon & Kenyon
Robert & Bosch GmbH
Tarcza Thomas H.
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