Test device for testing a distance sensor operating with ultrasonic waves

1. A test device for testing a distance sensor operating with ultrasonic waves, the test device comprising:

a test receiving element for receiving the ultrasonic waves emitted by the distance sensor to be tested;

at least one test radiating element for radiating test ultrasonic waves; and

a signal processing unit,

wherein the ultrasonic waves received by the test receiving element are transmitted as a received signal to the signal processing unit,

wherein the signal processing unit is configured to:

determine a duration of the received signal deemed as a single coherent received signal based on

resetting a ramp signal generator in response to an amplitude or an intensity of the received signal exceeding a first threshold,

determining a start of the duration based on the ramp signal generator being initially reset in response to the received signal, and

determining an end of the duration based on the output of the ramp signal generator exceeding a second threshold;

generate an excitation signal based on delaying, with respect to the received signal according to simulation distance information relating to a distance to be simulated, a copy of signal components of the received signal within the determined duration; and

transmit the excitation signal to the test radiating element,

wherein the test radiating element is configured to generate the test ultrasonic waves based on the excitation signal and radiate the test ultrasonic waves to the distance sensor to be tested.

2. The test device according to claim 1 , wherein test device distance information relating to a distance between the test device and the distance sensor to be tested is stored in the test device, and wherein the signal processing unit is configured to determine the excitation signal further based on the test device distance information.

3. The test device according to claim 1 , wherein the excitation signal and thus the test ultrasonic waves have a frequency, wherein the frequency is constant or time-variable for simulating a change in distance.

4. The test device according to claim 1 ,

wherein the received signal is sampled at a sampling frequency by the signal processing unit and stored as sampled received signal,

wherein the sampled received signal is transmitted at least indirectly as an output signal to the at least one test radiation element, and

wherein the sampling frequency is at least twice as high or at least ten times as high as a frequency of the ultrasonic waves emitted by the distance sensor to be tested.

5. The test device according to claim 1 , wherein a spacer with a defined length is arranged in a radiation direction of the at least one test radiating element such that the test device is placed at a defined distance from the distance sensor to be tested or a mounting location of the distance sensor to be tested.

6. The test device according to claim 1 ,

wherein the at least one test radiating element includes a plurality of test radiating elements,

wherein the signal processing unit is configured to determine a plurality of delayed excitation signals for the plurality of test radiating elements as a function of the received signal and the simulation distance information and transmits them to the test radiating elements, and

wherein the test radiating elements generate corresponding test ultrasonic waves of the test ultrasonic waves and radiate the test ultrasonic waves to the distance sensor to be tested or to a plurality of sensor receiving elements of the distance sensor to be tested.

7. The test device according to claim 2 , wherein an amplitude of the excitation signal is determined by the signal processing unit as a function of a corresponding amplitude of the received signal, as a function of the simulation distance information, or as a function of the test device distance information, or a combination thereof.

8. The test device according to claim 7 , wherein the amplitude of the excitation signal is determined by the signal processing unit further as a function of an object information of an object or as a function of an effective reflection surface of the object and/or reflection properties of the reflection surface of the object and/or a contour of the reflection surface of the object.

9. The test device according to claim 2 ,

wherein the signal processing unit is configured to operate the test device as another distance sensor, wherein a measurement signal is transmitted via the at least one test radiating element and a reflected measurement signal is detected by the test receiving element, the reflected measurement signal being transmitted as a received measurement signal to the signal processing unit, and

wherein the signal processing unit is configured to determine a signal propagation time and determine measured distance information from the signal propagation time, and wherein the measured distance information is stored as the test device distance information.