Patent Description:
In a conventional solution, a device under test (DUT) is tested for EMC. Typically, the DUT is exposed to an electromagnetic signal in an anechoic chamber. The electromagnetic signal is artificially created by a signal generator and e.g. may have a very high field strength. However, it is desired to test a DUT in more complex scenarios, which is why the signals which are artificially created by the signal generator are no longer sufficient. It is in particular desired to test the DUT in an electromagnetic environment (EME) which corresponds to a real world environment of the intended use case of the DUT.

<CIT> for example discloses a system for testing integrated radar systems. However, this solution fails to provide a complex electromagnetic signal which is required for effective EMC testing, as outlined above.

Prior art paper "<NPL>, discloses a test arrangement for vehicles; including an RF anechoic chamber, wherein actual signals are recorded outside of the chamber and played back inside the chamber following a calibration of the transmit chain using receivers in the chamber and corresponding adjustment of the transmission equipment.

Therefore, the object of the invention is to provide a method for testing devices which can emulate a real word EME in an anechoic chamber. Moreover, the object is to provide an according system and computer program.

The object is solved by the features of the first independent claim for the method and by the features of the second independent claim for the system. Further, it is solved by the features of an associated computer program product. The dependent claims contain further developments.

An inventive method for emulating an electromagnetic environment, EME, in an anechoic chamber comprises the steps of: receiving, by a first receiving unit, an input signal outside the anechoic chamber; generating, by a signal generating unit, an emulated signal based on the input signal; transmitting, by a transmitting unit, the emulated signal inside the anechoic chamber to emulate the EME; and adjusting, by the signal generating unit, the emulated signal generated by the signal generating unit based on the emulated signal transmitted by the transmitting unit.

This is beneficial, as e.g. a RF baseband signal (which may comprise an in-phase component and a quadrature component) can be captured and recorded (i.e. the input signal of the method). Based on the recorded signal, a test system can be calibrated for tests using broadband interferences signals of different bandwidth. Such a test system which can control and automate tests based on the recorded signal may e.g. comprise a RF vector generator, an in-phase component and a quadrature component baseband recorder, a RF Spectrum analyzer, a RF switching unit, a turntable, antenna mast and RF power amplifier. The recorded signal can be managed, e.g. with regards to center frequency, sampling rate, reference level and recording time. The invention also allows for saving and extracting a waveform file based on the input signal, transferring waveform files and playing back a real signal from a signal generator based in the waveform file. Further, a EME waveform playback similarity signature evaluation can be performed with the recorded trace (i.e. the input signal). Also, a frequency response adjustment can be performed to meet a desired field strength for testing in the test system.

That is, the method according to the present invention allows for emulating EME signal influence of a real-world scenario in an anechoic chamber systematically, objectively and safely.

As characteristics of real-world EME interference signals comprise narrowband or/and broadband signals along the time variation, the present invention ensures that these complex signals can be reproduced in an anechoic chamber via a transmitting unit with high similarity with the recorded signal of a defined bandwidth from the environment (i.e. the input signal to the method).

In particular, the adjusting, by the signal generating unit, the emulated signal generated by the signal generating unit based on the emulated signal transmitted by the transmitting unit allows for calibrating a test system to produce a test signal with a desired field strength and in order to ensure repeatability of the test. This also ensures safe operation of a test system, especially when signals of high field strength are generated. This is also beneficial, as a waveform playback similarity signature can be evaluated, to further adapt the emulated EME to a real world scenario recorded outside the anechoic chamber. Also, RF signal adjustment (of the signal that emulates the EME in the anechoic chamber) can be performed in order to reproduce the same waveform and achieve similar interference effects as in the recorded real world scenario.

In particular, emulating (that is, generating the emulated signal) includes generating an emulated signal by means of a signal generator, wherein the emulated signal corresponds to the input signal. Thereby, the input signal (which e.g. was recorded outside the anechoic chamber) is reproduced inside the anechoic chamber. The emulated signal thereby compensates for effects which arise due to the characteristics of the anechoic chamber, e.g. interference effects. That is, the emulated signal that is transmitted inside the anechoic chamber creates the same EME as it is present outside the anechoic chamber (represented by the input signal).

In particular, the input signal represents an EME that is present outside the anechoic chamber. In particular, the EME outside the anechoic chamber is present at a predefined spot where the input signal is received.

In particular, the input signal comprises an electromagnetic signal and/or an electromagnetic waveform. In particular, the input signal comprises a narrowband, a baseband and/or a wideband signal. In particular, the input signal comprises broadcast transmission, radar radiation, an out-of-band signal, environmental noise and/or influence from other transmitters. In particular, the input signal comprises a radio frequency baseband signal. In particular, the radio frequency baseband signal comprises an in-phase and/or a quadrature component.

In particular, the emulated signal comprises an electromagnetic signal and/or an electromagnetic waveform. In particular, the emulated signal comprises a narrowband, a baseband and/or a wideband signal. In particular, the emulated signal comprises broadcast transmission, radar radiation, an out-of-band signal, environmental noise and/or influence from other transmitters. In particular, the emulated signal comprises a radio frequency baseband signal. In particular, the radio frequency baseband signal comprises an in-phase and/or a quadrature component.

In particular, a device under test, DUT, can be placed inside the anechoic chamber.

In particular, the anechoic chamber is a room designed to completely absorb reflections of electromagnetic waves. In particular, anechoic means non-reflective, non-echoing and/or echo-free.

In particular, receiving the input signal by the first receiving unit comprises recording the input signal (e.g. by the first receiving unit or by the signal generating unit). The recorded signal can be of arbitrary length. In particular, the method further includes generating, by the signal generating unit, the emulated signal based on the recorded input signal.

In particular, the signal generating unit includes a signal amplification unit.

In particular, the adjusting of the emulated signal comprises applying a fast Fourier transformation, FFT, to the input signal and/or the emulated signal.

In particular, the transmitting unit comprises a transmitting circuit, and/or an antenna. In particular, the first receiving unit comprises a first receiving circuit, and/or an antenna. In particular, the second receiving unit comprises a second receiving circuit, and/or an antenna.

Advantageously and preferably, the method further comprises the steps of receiving, by a second receiving unit, the emulated signal inside the anechoic chamber; and adjusting, by the signal generating unit, the emulated signal generated by the signal generating unit based on the emulated signal received by the second receiving unit.

In particular, the second receiving unit includes a receiving antenna.

Advantageously and preferably, the method further comprises the steps of analyzing, by a spectrum analyzer, the emulated signal received by the second receiving unit to obtain an analyzing result, and adjusting, by the signal generating unit, the emulated signal generated by the signal generating unit based on the analyzing result.

Advantageously and preferably, the method further comprises the step of performing frequency response correction based on the input signal and/or the emulated signal and/or the analyzing result, to adjust the emulated signal.

In particular, the frequency response correction is based on an SMW-K544 algorithm, or on a similar algorithm.

In particular, the frequency response correction is performed in the signal generating unit and/or in the spectrum analyzer. In particular, the frequency response correction is performed in the signal generating unit and/or in the spectrum analyzer by means of test software. Advantageously and preferably, the input signal comprises a signal in the range from <NUM> to <NUM>, preferably in the range from <NUM> to <NUM>.

According to the invention, the method further comprises the step of performing a waveform similarity test based on the input signal; and based on the emulated signal generated by the signal generating unit and based on the emulated signal received by the second receiving unit.

In particular, the waveform similarity test may include converting at least one of the above signals or the result to a frequency domain for correction and magnitude adjustment.

In particular, the waveform similarity test may be performed in the signal generating unit and/or in the spectrum analyzer.

According to the invention, the method further includes the step of determining a performance of EME emulation, based on a result of the waveform similarity, wherein the performance is determined in the signal generating unit.

Advantageously and preferably, the first receiving unit is attached to a mobile unit, and the method further comprises the step of receiving the input signal during a test drive of the mobile unit.

In particular, the mobile unit can be a car, a truck, a plane, a helicopter, a drone, a boat, a pedestrian, or the like. In particular, the mobile unit can be driven by a human, and/or can be driven autonomous.

Advantageously and preferably, the input signal and/or the emulated signal comprises a fading component.

An inventive system for emulating an electromagnetic environment, EME, in an anechoic chamber comprises: a first receiving unit configured to receive an input signal outside the anechoic chamber; a signal generating unit configured to generate an emulated signal based on the input signal; a transmitting unit configured to transmit the emulated signal inside the anechoic chamber to emulate the EME; wherein the signal generating unit is further configured to adjust the emulated signal generated by the signal generating unit based on the emulated signal transmitted by the transmitting unit.

Advantageously and preferably, the system is configured to receive, by a second receiving unit of the system, the emulated signal inside the anechoic chamber; and to adjust, by the signal generating unit, the emulated signal generated by the signal generating unit based on the emulated signal received by the second receiving unit.

Advantageously and preferably, the system further comprises a spectrum analyzer configured to analyze the emulated signal received by the second receiving unit to obtain an analyzing result, wherein the signal generating unit is further configured to adjust the emulated signal generated by the signal generating unit based on the analyzing result.

Advantageously and preferably, the system is further configured to perform frequency response correction based on the input signal and/or the emulated signal and/or the analyzing result, to adjust the emulated signal.

In particular, the frequency response correction is performed in the signal generating unit and/or in the spectrum analyzer. In particular, the frequency response correction is performed in the signal generating unit and/or in the spectrum analyzer by means of test software.

Advantageously and preferably, the input signal comprises a signal in the range from <NUM> to <NUM>, preferably in the range from <NUM> to <NUM>.

According to the invention, the system is further configured to perform a waveform similarity test based on the input signal; and based on the emulated signal generated by the signal generating unit and based on the emulated signal received by the second receiving unit.

According to the invention, the system further includes determining a performance of EME emulation, based on a result of the waveform similarity test, wherein the performance is determined in the signal generating unit.

Advantageously and preferably, the first receiving unit is attached to a mobile unit of the system, and the system is further configured to receive the input signal during a test drive of the mobile unit.

The inventive system comprises the same advantages as the inventive method.

An inventive computer program product comprises program code for performing steps of the above described inventive method, when the computer program product runs on a computer or a digital signal processor.

The inventive computer program product comprises the same advantages as the inventive device.

An exemplary embodiment of the invention is now further explained with respect to the drawings by way of examples only, in which.

In the following, the function of an embodiment of the inventive method is described based on <FIG>. Then, based on <FIG>, structure and function of an embodiment of the inventive system are going to be described. In <FIG> and <FIG>, operating scenarios according to the present invention are described. <FIG> shows an illustrative view of a signal that can be used by the present invention, either as an input signal, or as an emulated signal to emulate the EME in the anechoic chamber.

<FIG> shows a method <NUM> for emulating an electromagnetic environment <NUM> in an anechoic chamber <NUM>. As illustrated in <FIG>, the method <NUM> comprises the steps of: receiving <NUM>, by a first receiving unit <NUM>, an input signal <NUM> outside the anechoic chamber <NUM>; generating <NUM>, by a signal generating unit <NUM>, an emulated signal <NUM> based on the input signal <NUM>; transmitting <NUM>, by a transmitting unit <NUM>, the emulated signal <NUM> inside the anechoic chamber <NUM> to emulate the EME <NUM>; and adjusting <NUM>, by the signal generating unit <NUM>, the emulated signal <NUM> generated by the signal generating unit <NUM> based on the emulated signal <NUM> transmitted by the transmitting unit <NUM>.

In a step, which is optional and therefore not shown in <FIG>, the emulated signal <NUM> can be received by a second receiving unit <NUM> inside the anechoic chamber <NUM>. The emulated signal <NUM> generated by the signal generating unit <NUM> is then adjusted based on the emulated signal <NUM> received by the second receiving unit <NUM>.

In another step, which is optional and therefore not shown in <FIG>, the emulated signal <NUM> that is received by the second receiving unit <NUM> is analyzed by a spectrum analyzer <NUM> to obtain an analyzing result. The emulated signal <NUM> generated by the signal generating unit <NUM> is then also adjusted based on the analyzing result.

<FIG> shows a system <NUM> according to an embodiment of the present invention. The system <NUM> is for emulating an electromagnetic environment, <NUM> in an anechoic chamber <NUM>.

To this end, the system <NUM> comprises a first receiving unit <NUM>, which is configured to receive an input signal <NUM> outside the anechoic chamber <NUM>. The system <NUM> further comprises a signal generating unit <NUM> configured to generate an emulated signal <NUM> based on the input signal <NUM>. The signal generating unit <NUM> may optionally also include an amplifier for amplifying the emulated signal <NUM> before transmitting it. The system <NUM> also comprises a transmitting unit <NUM> configured to transmit the emulated signal <NUM> inside the anechoic chamber <NUM>. By transmitting the emulated signal <NUM>, which corresponds to the obtained (and possibly recorded) input signal, inside the anechoic chamber, the EME <NUM> is emulated.

The signal generating unit <NUM> is further configured to adjust the emulated signal <NUM> generated by the signal generating unit <NUM> based on the emulated signal <NUM> transmitted by the transmitting unit <NUM>. This provides a feedback loop, according to which the emulated signal <NUM> can be calibrated to provide a desired field strength, and desired interference signals of different bandwidth, as this is also the case in a real world scenario outside the anechoic chamber, which is going to be emulated inside the anechoic chamber by the system <NUM>.

<FIG> also shows a second receiving unit <NUM> of the system <NUM>, which is an optional part of the system <NUM>. The emulated signal <NUM> is received by the second receiving unit <NUM> inside the anechoic chamber <NUM>. The second receiving unit e.g. can include an antenna. Then the emulated signal <NUM> generated by the signal generating unit <NUM> is adjusted based on the emulated signal <NUM> received by the second receiving unit <NUM>.

The system <NUM> further can comprise an optional spectrum analyzer, which is not shown in <FIG>. The spectrum analyzer can analyze the emulated signal <NUM> received by the second receiving unit <NUM> to obtain an analyzing result. The emulated signal <NUM> generated by the signal generating unit <NUM> is then adjusted also based on the analyzing result.

<FIG> shows a schematic view of an operating scenario according to the present invention. <FIG> is however just for illustrating the operating principle and therefore does not show all features which are e.g. described in view of <FIG> or <FIG>. The process shown in <FIG> is in particular shown over time, which is why several entities are shown twice.

As shown in <FIG>, an input signal <NUM> is received outside an anechoic chamber <NUM>. An emulated signal <NUM> is generated based on the input signal <NUM> and then transmitted by means of a transmitting unit <NUM>. Based on the input signal <NUM> and based on the emulated signal <NUM>, further calibration and adjustment of the emulated signal <NUM> can be performed, and the adjusted emulated signal <NUM> is again output by the transmitting unit <NUM>. The emulated signal <NUM> is applied to a DUT, as shown in <FIG>.

<FIG> shows a schematic view of another operating scenario according to the present invention. <FIG> is however just for illustrating the operating principle and therefore does not show all features which are e.g. described in view of <FIG> or <FIG>.

As shown in <FIG>, an input signal <NUM> is received by a first receiving unit <NUM>. An emulated signal <NUM> is then generated by a signal generating unit <NUM>, based on the input signal <NUM>. Although it is shown as a separate entity in <FIG>, the signal generating unit <NUM> may also include an amplifier for amplifying the emulated signal <NUM>. The emulated signal <NUM> is then provided to a transmitting unit <NUM>, where the emulated signal <NUM> is transmitted inside the anechoic chamber <NUM>. In the anechoic chamber <NUM>, the emulated signal <NUM> is received by means of a second receiving unit <NUM>. The received emulated signal <NUM> is provided to a spectrum analyzer <NUM>, which analyzes the received emulated signal <NUM> and provides and analyzation result. Further test software can be applied to the received emulated signal <NUM>, and/or the analyzing result, such as software implementing frequency response correction and/or a waveform similarity test. The received emulated signal <NUM> and/or the analyzing result are then provided to the signal generating unit <NUM>, where the emulated signal <NUM> which is provided by the signal generating unit <NUM> is adjusted based on the received emulated signal <NUM>, and/or based on the analyzing result.

<FIG> shows a schematic view of signals processed by the present invention. The shown signals can be included in the input signal <NUM>, and/or in the emulated signal <NUM>. The signals shown in <FIG> include frequency modulated signals FM1 in the typical spectrum of radio broadcast communication. The signals shown in <FIG> include signals PTT2 in the typical spectrum of push-to-talk handheld radios. The signals shown in <FIG> include signals LTE3 in the typical spectrum of LTE user equipments UEs, or base stations. That is, the input signal <NUM> and/or the emulated signal <NUM> can include at least one component in the range from <NUM> to <NUM>, preferably in the range from <NUM> to <NUM>. In particular, the signal <NUM> and/or the emulated signal <NUM> additionally or alternatively can also include at least one component from <NUM> Frequency Range <NUM> (FR2), which includes frequency bands from <NUM> to <NUM>.

It is important to note that the inventive system and method very closely correspond. Therefore, all of the above said regarding the system is also applicable to the method and vice versa. Everything which is described in the description and/or claimed in the claims and/or drawn in the drawings can be combined.

Claim 1:
A method (<NUM>) for emulating an electromagnetic environment, EME, (<NUM>) in an anechoic chamber (<NUM>), the method (<NUM>) comprising the steps of:
- receiving (<NUM>), by a first receiving unit (<NUM>), an input signal (<NUM>) outside the anechoic chamber (<NUM>);
- generating (<NUM>), by a signal generating unit (<NUM>), an emulated signal (<NUM>) based on the input signal (<NUM>);
- transmitting (<NUM>), by a transmitting unit (<NUM>), the emulated signal (<NUM>) inside the anechoic chamber (<NUM>) to emulate the EME (<NUM>);
- adjusting (<NUM>), by the signal generating unit (<NUM>), the emulated signal (<NUM>) generated by the signal generating unit (<NUM>) based on the emulated signal (<NUM>) transmitted by the transmitting unit (<NUM>);
- receiving, by a second receiving unit (<NUM>), the emulated signal (<NUM>) inside the anechoic chamber (<NUM>);
- adjusting, by the signal generating unit (<NUM>), the emulated signal (<NUM>) generated by the signal generating unit (<NUM>) based on the emulated signal (<NUM>) received by the second receiving unit (<NUM>);
- performing a waveform similarity test based on the input signal (<NUM>) and based on the emulated signal (<NUM>) generated by the signal generating unit (<NUM>) and based on the emulated signal (<NUM>) received by the second receiving unit (<NUM>); and
- determining, by the signal generating unit (<NUM>), a performance of EME emulation based on a result of the waveform similarity test.