Direction finding method and direction finding system

1 . A direction finding method of determining bearings of radio signals by a direction finding system, the direction finding system comprising at least two antennas, at least two receivers being coupled with one of the at least two antennas, respectively, at least two analog-to-digital converters (ADCs), a pre-processing circuit, and an analysis circuit, the direction finding method comprising the steps of:

receiving, by the at least two receivers, electromagnetic waves via the at least two antennas, thereby obtaining at least two input signals;

digitizing, by the at least two ADCs, the at least two input signals, thereby obtaining at least two digitized input signals;

generating, by the pre-processing circuit, input signal data based on the at least two digitized input signals;

determining, by the analysis circuit, whether the received electromagnetic waves comprise at least one useful signal based on the input signal data;

determining, by the analysis circuit, a bearing of a first useful signal based on the input signal data;

removing, by the analysis circuit, data corresponding to the first useful signal from the input signal data, thereby obtaining modified input signal data, wherein the modified input signal data corresponds to the received electromagnetic waves with the first useful signal removed;

determining, by the analysis circuit, whether the modified input signal data comprises at least one further useful signal;

determining, by the analysis circuit, a bearing of a second useful signal based on the modified input signal data; and

removing, by the analysis circuit, data corresponding to the second useful signal from the modified input signal data.

2 . The direction finding method of claim 1 , wherein a binary quantity is determined by the analysis circuit, wherein the binary quantity is indicative of whether the received electromagnetic waves comprise at least one useful signal.

3 . The direction finding method of claim 1 , wherein the analysis circuit comprises a machine-learning circuit, wherein the machine-learning circuit is pre-trained to determine whether the received electromagnetic waves comprise at least one useful signal, determine bearings of useful signals and/or remove data corresponding to useful signals from the input signal data.

4 . The direction finding method of claim 3 , wherein the machine-learning circuit comprises a first machine-learning sub-circuit that is pre-trained to determine whether the received electromagnetic waves comprise at least one useful signal and to determine bearings of useful signals.

5 . The direction finding method of claim 3 , wherein the machine-learning circuit comprises a second machine-learning sub-circuit that is pre-trained to remove data corresponding to useful signals from the input signal data.

6 . The direction finding method of claim 3 , wherein the machine-learning circuit comprises at least one artificial neural network.

7 . The direction finding method of claim 1 , wherein the input signal data comprises a complex-valued covariance matrix associated with the at least two digitized input signals.

8 . The direction finding method of claim 7 , wherein a real-valued vector or a complex-valued vector is determined based on the complex-valued covariance matrix.

9 . The direction finding method of claim 1 , wherein the input signal data comprises IQ data associated with the at least two digitized input signals.

10 . The direction finding method of claim 1 , wherein the input signal data comprises frequencies of the input signals and/or signal strengths of the input signals.

11 . The direction finding method of claim 1 , wherein the input signals are integrated over a predetermined reception time, thereby obtaining accumulated signals.

12 . The direction finding method of claim 1 , wherein a quality metric associated with the first useful signal is determined.

13 . The direction finding method of claim 1 , wherein a confidence metric associated with the determined bearing of the first useful signal is determined.

14 . The direction finding method of claim 1 , wherein a predefined frequency band is selected by the at least two receivers, respectively.

15 . The direction finding method of claim 1 , wherein noise in the at least two digitized input signals is discarded in order to determine whether the received electromagnetic waves comprise at least one useful signal.

16 . A direction finding system for determining bearings of radio signals, wherein the direction finding system comprises

at least two antennas being configured to receive electromagnetic waves;

at least two receivers being coupled with one of the at least two antennas, respectively, wherein the at least two receivers are configured to convert the electromagnetic waves into an input signal, respectively, thereby obtaining at least two input signals;

at least two analog-to-digital converters (ADCs), the at least two ADCs being configured to digitize the at least two input signals, thereby obtaining at least two digitized input signals;

a pre-processing circuit being configured to pre-process the at least two digitized input signals, thereby obtaining input signal data being associated with the at least two digitized input signals; and

an analysis circuit, wherein the analysis circuit is configured to determine whether the received electromagnetic waves comprise at least one useful signal based on the input signal data, wherein the analysis circuit is configured to determine a bearing of a first useful signal based on the input signal data, and wherein the analysis circuit is configured to remove data corresponding to the first useful signal from the input signal data, thereby obtaining modified input signal data, wherein the modified input signal data corresponds to the received electromagnetic waves with the first useful signal removed, wherein the analysis circuit is configured to determine whether the modified input signal data comprises at least one further useful signal, and wherein the analysis circuit is configure to determine a bearing of a second useful signal based on the modified input signal data.

17 . The direction finding system of claim 16 , wherein the analysis circuit comprises a machine-learning circuit, wherein the machine-learning circuit is pre-trained to determine whether the received electromagnetic waves comprise at least one useful signal, determine bearings of useful signals and/or remove data corresponding to useful signals from the input signal data.

18 . The direction finding system of claim 17 , wherein the machine-learning circuit comprises a first machine-learning sub-circuit that is pre-trained to determine whether the received electromagnetic waves comprise at least one useful signal and to determine bearings of useful signals, and/or wherein the machine-learning circuit comprises a second machine-learning sub-circuit that is pre-trained to remove data corresponding to useful signals from the input signal data.

19 . A direction finding system for determining bearings of radio signals, wherein the direction finding system comprises

at least two antennas being configured to receive electromagnetic waves;

at least two receivers being coupled with one of the at least two antennas, respectively, wherein the at least two receivers are configured to convert the electromagnetic waves into an input signal, respectively, thereby obtaining at least two input signals;

at least two analog-to-digital converters (ADCs), the at least two ADCs being configured to digitize the at least two input signals, thereby obtaining at least two digitized input signals;

a pre-processing circuit being configured to pre-process the at least two digitized input signals, thereby obtaining input signal data being associated with the at least two digitized input signals; and

an analysis circuit, wherein the analysis circuit is configured to determine whether the received electromagnetic waves comprise at least one useful signal based on the input signal data, wherein the analysis circuit is configured to determine a bearing of a first useful signal based on the input signal data, and wherein the analysis circuit is configured to remove data corresponding to the first useful signal from the input signal data, thereby obtaining modified input signal data,

wherein the analysis circuit comprises a machine-learning circuit,

wherein the machine-learning circuit comprises a first machine-learning sub-circuit that is pre-trained to determine whether the received electromagnetic waves comprise at least one useful signal and to determine bearings of useful signals, and

wherein the machine-learning circuit comprises a second machine-learning sub-circuit that is pre-trained to remove data corresponding to useful signals from the input signal data.