摘要:
Using a radar system in a motor vehicle, high frequency individual signal pulses are transmitted from at least one transmitting antenna, and at least one receiving antenna receives reception signals formed by reflection of the transmitted signal pulses from objects in the surroundings. The reception signals are mixed with the high-frequency signal to produce low-frequency mixed signals representing the sequence of individual signal pulses. The phase angle of the mixed signals is varied over successive individual signal pulses thereof by varying the phase angle of: the successive individual transmitted signal pulses, the high-frequency signals used for the mixing, and/or the mixed signals. In further processing of the mixed signals to determine the distance and the relative velocity of detected objects, an interference component can be separated and/or suppressed from a useful signal component because the useful signal component has the known phase angle variation but the interference component does not.
摘要:
A radar system for recording the environment of a motor vehicle includes transmission antennas for emitting transmission signals, receiver antennas for receiving transmission signals reflected by objects in the environment, and a signal processor for processing the received signals. The antennas are planar and are situated on a level surface. Received signals are acquired from different combinations of the transmitter and receiver antennas. In the signal processor, the angular position of objects in a spatial direction R is estimated from the received signals, based on recognition that the received signals from an individual object have different phase positions depending on the angular position of the object in the spatial direction R. Two of the transmitter and receiver antennas overlap in the spatial direction R without coinciding, by special arrangements or configurations of the transmitter and receiver antennas.
摘要:
In a method for suppressing interferences while detecting objects in a target area, a transmitter transmits a sequence of pulses into the target area, and a receiver detects the resulting reflection signal of the pulses reflected from the objects, within successive time windows that are referenced to the moment of transmitting an individual pulse and thus represent distance gates. The time spacing between the successive individual pulses is variable and randomized according to the pseudo-noise principle within predetermined limits, and the time windows are adapted accordingly. The received reflection signal may be sampled, digitized, digitally pre-processed and digitally filtered in the individual distance gates. A non-linear digital filter, preferably a sliding median filter, is used for the filtering to suppress transient disturbances. The median is determined from an odd number of consecutive sampled values of a reflection signal detected within a distance gate.
摘要:
Circuits generate an IQ voltage or current signal having orthogonal I- and Q-parts of approximately equal amplitude from an electric input signal having a frequency varying slightly around a carrier frequency, without needing a complex mixer. The circuit includes at least one ohmic resistance and at least one reactance connected in series (for a voltage) or in parallel (for a current). The reactance has an impedance at the carrier frequency approximately matching the resistance value of the ohmic resistance. The I- and Q-parts of the voltage signal are tapped as voltage drops across the resistance and the reactance. With two such series circuit branches in parallel, both voltage signal parts can be referenced directly to a reference potential, e.g. ground. The I- and Q-parts of the current signal are tapped as currents flowing through the resistance and the reactance. The circuit can be integrated at the output of a bandpass filter.
摘要:
Circuits generate an IQ voltage or current signal having orthogonal I- and Q-parts of approximately equal amplitude from an electric input signal having a frequency varying slightly around a carrier frequency, without needing a complex mixer. The circuit includes at least one ohmic resistance and at least one reactance connected in series (for a voltage) or in parallel (for a current). The reactance has an impedance at the carrier frequency approximately matching the resistance value of the ohmic resistance. The I- and Q-parts of the voltage signal are tapped as voltage drops across the resistance and the reactance. With two such series circuit branches in parallel, both voltage signal parts can be referenced directly to a reference potential, e.g. ground. The I- and Q-parts of the current signal are tapped as currents flowing through the resistance and the reactance. The circuit can be integrated at the output of a bandpass filter.
摘要:
A radar antenna arrangement, in particular for motor vehicles, is presented, having of a longitudinal waveguide, into which electromagnetic waves are coupled in such a manner that they expand in the longitudinal direction (X) of the waveguide, and an interference structure (12) with a plurality of metallic sections, whereby the interference structure in proximity to the waveguide, at a distance from the waveguide in a first transverse direction (Y) to the waveguide, is arranged at least approximately parallel to the longitudinal direction (X) of the waveguide, so that the interference structure effects an adjusted radiation of the radar waves. The waveguide comprises in the longitudinal direction two metallic surfaces (31, 41) and between these, a dielectric medium (32, 42), whereby the surfaces (31, 41) run in a second transverse direction (Z), which stands both vertically to the first transverse direction (Y) and to the longitudinal direction (X) of the waveguide. Preferably, the interference structure (12) is designed as a rotatable drum with metallic sections which are changed on the circumference and a reflector arrangement is provided for bundling and polarising the waves.
摘要:
In a frequency-modulated radar system and method for detecting the surroundings, a compensation of interfering effects is achieved by varying one of the following values: a) a time spacing or temporal distance between the transmitted frequency ramps or the time gap between the frequency ramps, b) a time from the start of the respective transmitted frequency ramp to the beginning of the scanning of the received signal, c) a frequency at the start of the transmitted frequency ramp, and d) a sign of the slope of the transmitted frequency ramps.
摘要:
A radar sensor includes a housing of radar-transmissive material, a circuit board in the housing, first and second antennas of several patch elements on the same or opposite surfaces of the circuit board, and a metal or metallized support supporting a rear surface of the circuit board. The first antenna has a beam axis that extends out through a front of the housing at an angle in a range from 45° to 90° relative to the circuit board plane. The sensor further includes a beam deflection structure arranged within the housing to deflect a beam axis of the second antenna out through the housing at an angle in a range from 0° to 45° relative to the circuit board plane.
摘要:
A radar system transmits signals for recording the environment of a motor vehicle, and the signals are reflected back from objects in the environment. Received signals are acquired from different combinations of transmitter and receiver antennas of the system. With regard to a series of such antenna combinations having their respective phase centers ordered in a spatial direction R, the positions of the phase centers of the combinations vary periodically with the period length P in a spatial direction S that runs perpendicular to the spatial direction R. Signal processing circuitry makes conclusions about the position of an object in the spatial direction S, based on an evaluation that the received signals from the object have a phase portion that alternates with the period length P over the antenna combinations ordered as set forth above, depending on the angular position of the object in the spatial direction S.
摘要:
Input values are non-linearly digitally filtered to produce as an output value the Rth-largest value among the K input values, wherein the Rth-largest value may be the median value with R=(K+1)/2. The input values are provided in any binary fixed point number representation. A respective selected bit of all the input values is evaluated to determine the Rth-largest bit value of this bit among the K input values, and this gives the value of the corresponding bit of the output value. In the input values of which the selected bit does not correspond to the determined Rth-largest bit value, all of the subsequent less-significant bits are set as dummy bits equal to the selected bit, which excludes these input values from being the Rth-largest value in the subsequent evaluation of the successive less-significant bits. Then these steps are repeated for the next selected less-significant bit, and so forth, thereby respectively determining the successive bits of the output value. Minor modifications are necessary depending on the particular numerical representation. The method can be used for implementing digital filters, in particular for signal processing in systems for object recognition.