Measurement device and method of operating a measurement device

Abstract

A measurement device such as a signal analyzer, spectrum analyzer or vector network analyzer is connected 11 to a device under test (DUT). A signal impairment parameter, such as a noise figure of the

Description

MEASUREMENT DEVICE AND METHOD OF OPERATING A MEASUREMENT DEVICE TECHNICAL FIELD The present disclosure relates to a measurement device, in particular a signal and / or spectrum analyzer, and to a method of operating such a measurement device. BACKGROUND Signal and spectrum analyzers are essential instruments for measuring and analyzing the characteristics of RE signals and the devices generating said signals. For instance, they provide detailed information on signal frequency, amplitude, phase, and other key signal parameters. To optimize the performance of a signal analyzer, an RF frontend of the analyzer can be adjusted to a current signal type and power level. This adaption can be realized by a so-called automatic leveling (autolevel) algorithm. Usually, autolevel only optimizes the analyzer itself by considering internal parameters of the signal analyzer respectively its frontend. However, the characteristics of the device which generates the signal to be measured, e.g. a device-under-test, is thereby not considered. SUMMARY Thus, it is an objective to further improve the performance of a measurement device, in particular a signal and / or spectrum analyzer . The objective is achieved by the solution provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims . According to a first aspect, the present disclosure relates to a method of operating a measurement device, in particular a signal and / or spectrum analyzer. The method comprises: connecting a device-under-test (DUT) to a radio frequency (RF) front end of the measurement device; receiving and / or measuring one or more signal impairment parameters of the DUT and / or of a user equipment attached to the DUT; and adapting a configuration of the RF front end based on at least one of the signal impairment parameters. This achieves the advantage that signal impairment parameters of the DUT (and a connected UE) can be considered when adapting the RF front end. In this way, a performance of the measurement device when processing / analyzing RF signals from the DUT can be enhanced. For instance, a figure of merit (e.g., an internal error vector magnitude or a signal-to-interference ratio) of the measurement device is optimized for a given signal bandwidth and power of the RF signal. For example, the measurement device executes an autolevel algorithm to adapt the RF front end, wherein the autolevel algorithm takes the one or more signal impairment parameters of the DUT and / or the user equipment into account. The configuration of the RF front end can further be adjusted based on characteristics of the measurement device itself (e.g., including all connected devices up to the DUT) and / or signal characteristics of RF signal (s) received from the DUT. This information can be fed together with the signal impairment parameters of the DUT and / or user equipment to the autolevel algorithm. The RF front end can comprise at least one RF port for connecting the DUT. The RF front end can be a receiver stage of the measurement device. For example, the RF front end is adapted to process an incoming RF signal from the DUT before the signal is converted to an intermediate frequency. For example, the method further comprises receiving an RF signal from the DUT and processing said RF signal with the RF front end based on the adapted configuration. The RF front end can be adjustable to different front end configurations. In particular, adapting a configuration of the RF front end may refer to adapting a setting and / or an internal parameter of the RF front end. For instance, an attenuation of the RF front end (i.e., an attenuation of the received RF signal in the front end) can be adapted. The measurement device can be a test and / or measurement instrument. For instance, the measurement device is a signal analyzer, a spectrum analyzer and / or a vector network analyzer . The signal impairment parameters can be automatically measured by the measurement device after connecting the DUT and / or after receiving a respective user command. The DUT can be an RF device. For instance, the DUT is a one port device (e.g., an antenna) or a two port device (e.g., an attenuator or a filter). The user equipment can be a component, such as a cable or an amplifier, which is arranged between the DUT and the measurement device. For instance, the influence of such user equipment (e.g., its impairment parameters) can be measured in the same ways as the impairment parameters of a DUT directly connected or connected via perfect user equipment to the measurement device. The user equipment could also comprise a communication device, e.g. a mobile device. The DUT could be a component of the user equipment, or vice versa. In an embodiment, at least one of the signal impairment parameters is received via a user input on a user interface of the measurement device. In an embodiment, the signal impairment parameters comprise a third-order-intercept point, TOI, of the DUT and / or of the user equipment. In an embodiment, the signal impairment parameters comprise a noise figure, NF, of the DUT and / or the user equipment. For example, the NF of the DUT and / or the user equipment is measured by: measuring a total NF of the measurement device and of the DUT and / or the user equipment, measuring or providing the NF of the measurement device only, and deriving the NF of the DUT and / or the user equipment from the total NF and from the NF of the measurement device. For instance, the NF of the DUT and / or the user equipment can be calculated by subtracting the NF of the measurement device from the total NF. In an embodiment, the NF of the DUT and / or the user equipment is measured by means of an I / Q noise cancellation measurement. In an embodiment, at least one of the signal impairment parameters is measured by means of an AM / AM and / or an AM / PM conversion measurement. Hereby, AM stands for amplitude modulation and PM for phase modulation. In an embodiment, the user equipment is de-embedded for measuring at least one signal impairment parameter of the DUT. In an embodiment, the method further comprises storing the received and / or measured signal impairment parameters in a memory of the measurement device. This achieves the advantage that the stored parameters can be used for multiple measurements in the future. In an embodiment, the method further comprises displaying the signal impairment parameters and / or an indication if the signal impairment parameters necessitate the adaption of the configuration of the RF front end. In an embodiment, the configuration of the RF front end is adapted to optimize a figure of merit of the measurement device . For instance, the figure of merit describes a quality of an analysis of the RF signal with the measurement device. The figure of merit may refer to an internal error vector magnitude (EVM) of the measurement device or specifically of the RF front end, wherein the at least one parameter of the RF front end is adapted to minimize the internal EVM. In an embodiment, the configuration of the RF front end comprises an attenuation of the RF front end. For instance, in this way a TOI of the RF front end can be adjusted. For instance, the method further comprises determining at least one RF characteristic of the DUT based on the received RF signal. According to a second aspect, the present disclosure relates to a measurement device, in particular a signal and / or spectrum analyzer. The measurement device comprises: an RF front end adapted for being connected to a device-under-test (DUT); an interface configured to receive and / or a measurement unit configured to measure one or more signal impairment parameters of the DUT and / or of a user equipment attached to the DUT; wherein the RF front end is configured to adapt its configuration based on at least one of the signal impairment parameters . In an embodiment, the RF front end is configured to receive an RF signal from the DUT and to process said RF signal based on the adapted configuration. In an embodiment, the interface comprises a user interface configured to receive at least one of the signal impairment parameters via a user input. In an embodiment, the measurement unit is configured to carry out: an I / Q noise cancellation measurement to determine at least one of the signal impairment parameters, and / or an AM / AM and / or an AM / PM conversion measurement to determine at least one of the signal impairment parameters. In an embodiment, the signal impairment parameters comprise a third-order-intercept point, TOI, of the DUT and / or of the user equipment. In an embodiment, the signal impairment parameters comprise a noise figure, NF, of the DUT and / or the user equipment. For example, the measurement unit is configured to measure the NF of the DUT and / or the user equipment by: measuring a total NF of the measurement device and of the DUT and / or the user equipment, measuring the NF of the measurement device only, and deriving the NF of the measurement device from the total NF and the NF of the DUT and / or the user equipment. In an embodiment, the user equipment is de-embedded for measuring at least one signal impairment parameter of the DUT. In an embodiment, the measurement device comprises a memory configured for storing the received and / or measured signal impairment parameters. In an embodiment, the measurement device comprises a display configured for displaying the signal impairment parameters and / or an indication if the signal impairment parameters necessitate the adaption of the configuration of the RF front end (i.e., if the impairment parameters are relevant for autoleveling). In an embodiment, the RF front end configured to adapt its configuration to optimize a figure of merit of the measurement device . In an embodiment, the configuration of the RF front end comprises an attenuation of the RF front end. 5 In an embodiment, the measurement device is configured for determining at least one RF characteristic of the DUT based on the received RF signal. BRIEF DESCRIPTION OF THE DRAWINGS 0 The above-described aspects and implementations are explained in the following description of embodiments with respect to the enclosed drawings: 15 Fig. 1 shows steps of a method of according to an operating a embodiment ; measurement device 20 Fig. 2 shows steps of measurement device a method of according to an operating a embodiment ; Fig. 3 shows a schematic device according to diagram of an embodiment; a measurement 25 Fig. 4 shows a schematic device according to diagram of an embodiment; a measurement and 30 Fig. 5 shows a user interface of a measurement device according to an embodiment. DETAILED DESCRIPTION OF EMBODIMENT Fig. 1 shows a method 10 of operating a measurement device according to an embodiment. The measurement device can be an electronic instrument for analyzing a DUT and / or an RF signal received from the DUT. For example, the measurement device is a signal, a spectrum analyzer and / or a vector network analyzer . The method 10 comprises the following steps: connecting 11 the DUT to an RF front end of the measurement device; receiving and / or measuring 12 one or more signal impairment parameters of the DUT and / or of a user equipment which is attached and / or connected to the DUT; and adapting 13 a configuration of the RF front end based on at least one of the signal impairment parameters . For example, the method 10 further comprises: receiving 14 an RF signal from the DUT and processing said RF signal with the RF front end based on the adapted configuration. For instance, the RF front end can adapt an internal attenuation based on the impairment parameters and apply said adapted attenuation to the RF signal. By adapting 13 the RF front end based on the signal impairment parameters of the DUT and / or the user equipment, a figure of merit of the measurement device can be optimized. For example, an internal error vector magnitude of the measurement device can be reduced and / or a signal-to-interference ratio can be enhanced for a given signal bandwidth and / or power of the RF signal received 14 from the DUT. For instance, the RF front end is adapted 13 by means of an autolevel technique. Thereby, an autolevel algorithm, which takes into account the signal impairment parameters, is executed by the measurement device or more specifically by a processor of the measurement device. For instance, the autolevel algorithm prepends the DUT in the signal chain. Additional parameters can be taken into account, when adapting 13 the RF front end. These additional parameters can comprise 5 characteristics of the measurement device itself and / or signal characteristics of RF signals received from the DUT. The characteristics of the measurement device can comprise further signal impairment parameters, such as NS, TOI and / or gain, of components of the measurement device or more specifically of 10 the RF front end. The signal characteristics can comprise a signal type, a power level and / or a bandwidth of RF signals received from the DUT. For instance, the measurement device configures itself based 15 on the signal impairment parameters or has a user configure the settings that optimize the figure of merit. For example, at least some of the signal impairment parameters can be received 12 by means of a user input on a user 20 interface, e.g. a graphical user interface (GUI), or an application programming interface (API) of the measurement device. In other words, a user can directly set the signal impairment parameters which are then used to adapt 13 the RF front end. 25 Alternatively or additionally, at least one signal impairment parameter could also be received via a communication interface of the measurement device. 30 Furthermore, a user can instruct the measurement device to measure the signal impairment parameters via the user input. For instance, the user can configure a measurement algorithm executed by the measurement device to measure the signal impairment parameters. The measurement device could also automatically measure the signal impairment parameters when connecting the DUT. The DUT can be a two-port device which is connected to at least two RF ports of the RF front end. For measuring the signal impairment parameters and / or for analyzing the DUT, the RF front end can forward RF test signals to the DUT via one of its RF ports and receive a response signal from the DUT (e.g., a reflection or transmission of the RF test signal) on the same or a different RF port. Thus, the RF signal(s) received from the DUT can be first used to measure the signal impairment parameter(s) and to adapt the RF front end (e.g., in case the signal impairment parameters are not receive via user input). Then, the RF signal(s) and / or the DUT can be further analyzed by the measurement device with improved performance due to the adapted configuration of the RF front end. The one or more signal impairment parameters can comprise a third-order intercept point (TOI) and / or a noise figure (NF) of the DUT and / or of the user equipment attached to the DUT. Thereby, the TOI can represent the level of input or output signal power at which the power of a third-order intermodulation product equals the power of the fundamental signal. The NF can be defined as the difference (e.g., in dB) between a noise output of an actual receiver to a noise output of an "ideal" receiver with the same overall gain and bandwidth at a standard noise temperature. Thereby, the NF of the DUT and / or the user equipment can be measured 12 by: measuring a total NF of the measurement device and of the DUT and / or the user equipment, measuring or providing the NF of the measurement device only, and deriving the NF of the measurement device from the total NF and the NF of the DUT and / or the user equipment (e.g., by subtraction). For instance, the total NF (of DUT and measurement device) and / or the NF of the measurement device can be measured by means of an I / Q noise cancellation (IQNC) measurement. In particular, during such an I / Q noise cancellation measurement, the measurement device may record a number N of I / Q captures. Out of the N captures, N-l can be used to derive an I / Q averaged signal (with reduced noise). The additional capture can be statistically independent (regarding noise) and can thus be used to derive a representative noise vector after subtracting the I / Q averaged signal. The NFs could be derived from the I / Q captures, the averaged signal and / or the noise vector . By performing such an IQNC measurement with the connected DUT, the total NF can be determined. The NF of only the measurement device can be known or also measured from an IQNC measurement. The measurement device can have an impedance of 50 ohm. For example, when analyzing the DUT with the measurement device, the I / Q captures used for I / Q noise cancellation can be used to additionally apply an error vector magnitude averaging on the remaining noise contribution (e.g. from the DUT) . As a consequence, this approach can have comparable or even faster measurement speeds compared to a conventional compliant N times demodulation plus averaging, while at the same time providing I / Q noise cancellation. Furthermore, at least one of the signal impairment parameters, in particular the TOI, can be derived from an AM / AM and / or an AM / PM conversion measurement. For instance, in both AM / AM and AM / PM conversion measurements, the measurement device forwards an RF test signal (input signal) to the DUT and records a response signal (output signal). In the AM / AM conversion measurement, the measurement device thereby measures how the amplitude of the output signal changes in response to changes in the amplitude of the input signal, e.g., due to non-linear gain characteristics of the DUT and / or the user equipment (amplifier measurement). In the AM / PM conversion measurement, the measurement device measures how the phase of the output signal changes in response to changes in the amplitude of the input signal, e.g., due to a phase distortion introduced by the DUT and / or the user equipment. For instance, the user equipment can be de-embedded to isolate the DUT when measuring at least one signal impairment parameter of the DUT. As shown in Fig. 1, the method 10 can comprise the optional steps of: storing 17 the received and / or measured signal impairment parameters in a memory of the measurement device, and / or displaying 16 the signal impairment parameters and / or an indication if the signal impairment parameters the adaption 13 of the configuration of the RF front end. For instance, the memory can store 17 the signal impairment parameters (e.g., NF) from a former measurement (e.g., save NF result from IQNC measurement and use it for further adaptions 13 of the RF front end under the assumption that the DUT didn't change). In this way, the stored signal impairment parameters can be used for autoleveling of multiple measurements. Alternatively, an extra measurement can be carried out for each new autolevel run. The measurement device can comprise a display for displaying 16 the signal impairment parameters and / or a graphical user interface on which the user can input the signal impairment parameters . For instance, the step of adapting 13 the configuration of the RF front end may comprise adapting an attenuation of the RF front end. For instance, the RF front end 21 can comprise an adjustable attenuator whose attenuation can be adapted based on the signal impairment parameter (s) . For instance, in this way a TOI of the RF front end can be adjusted. As shown in Fig. 1, the method 10 may comprise the further step of: determining 15 at least one RF characteristic of the DUT based on the received RF signal. This may refer to a conventional analysis of the RF signal and / or the DUT which is carried out with the measurement device. For instance, the measurement device is a signal and / or spectrum analyzer, and the RF characteristic refers to a signal parameter of the RF signal, such as a spectrum, a signal level, a phase or a bandwidth. Due to the adaption 13 of the RF front end (i.e., the improved autoleveling that takes into account DUT impairments), this analysis of the DUT can be carried out with an increased measurement accuracy and speed. Fig. 2 shows steps of the method 10 for operating the measurement device according to an embodiment. In particular, Fig. 2 shows a possible implementation of method steps 12 and 13 . As shown in Fig. 2, step 12 can comprise a receiving 12a of signal impairment parameters (NF and / or TOI) from a user via a graphical user interface (GUI) and a measuring 12b of the signal impairment parameters. The measurement 12b can be carried out automatically, e.g., after connecting 11 the DUT. It is also possible that when receiving 12a the parameters from a user, a measurement 12b is automatically carried out after a certain amount of time to update the received parameters . Furthermore, the step of adapting 13 the configuration of the RF front end can comprise executing 13a an autolevel algorithm and subsequently optimizing 13b the configuration of the RF front end based on the results of the algorithm (e.g., adapting an attenuation of the RF front end, etc.). Fig. 3 shows a schematic diagram of the measurement device 20 according to an embodiment. For instance, the measurement device 20 as shown in Fig. 3 can be operated according to the method 10 as shown in any one of Figs. 1 and 2. The measurement device 20 comprises an RF front end 21 adapted for being connected to the DUT 30. The measurement device 20 further comprises an interface 22 configured to receive and / or a measurement unit 23 configured to measure the one or more signal impairment parameters of the DUT 30 and / or of the user equipment which is attached and / or connected to the DUT 30. The RF front end 21 is configured to adapt its configuration based on at least one of the signal impairment parameters. For example, the RF front end 21 is further configured to receive the RF signal from the DUT 30 and to process said RF signal based on the adapted configuration. The interface 22 can comprise a user interface configured to receive at least one of the signal impairment parameters via a user input. For instance, the measurement device 20 comprises a display, e.g. a touch sensitive display, which is configured to show the user interface (e.g., in the form of a GUI). The measurement unit 23 can be configured to carry out the aforementioned I / Q noise cancellation measurement (s) and / or the AM / AM and / or an AM / PM conversion measurement (s) in order to determine at least one of the signal impairment parameters. For example, the measurement device 20 comprises a signal generator configured to generate RF test signals which is forwarded to the DUT, wherein the measurement unit is configured to measure an amplitude and / or phase modulation of a response signal which is received from the DUT 30 in response to the test signal. The measurement unit can comprise or be connected to a processor of the measurement device for analyzing the response signal. The RF front end 21 can be a receiver stage of the measurement device. For example, the RF front end 21 is adapted to process an incoming RF signal from the DUT 30 before the signal is converted to an intermediate frequency. This processing can comprise an attenuation, a (pre)amplification, a conversion and / or a digitization of the RF signal. The RF front end can comprise at least one RF port for connecting the DUT. For example, the measurement device 20 is a signal analyzer or a spectrum analyzer. As such, the measurement device 20 can determine at least one RF characteristic of the DUT 30 and / or the user equipment based on the received RF signal. For instance, the RF characteristic refers to a parameter (e.g., spectrum, signal magnitude, bandwidth etc.) of the RF signal provided by the DUT. Due to the adaption of the RF front end 21 (i.e., the improved autoleveling that takes into account DUT impairments), this analysis of the DUT 30 can be carried out with an increased measurement accuracy and speed. The DUT 30 can be an RF device. For instance, the RF device is a one port device (e.g., an antenna) or a two port device (e.g., an attenuator or a filter). The user equipment can be a component, such as a cable or an amplifier, which is arranged between the DUT 30 and the measurement device 20. For instance, the user equipment (e.g., cable) is attached to a DUT port and / or to a port of the measurement device 20. The user equipment can further be a communication device (e.g., a mobile device or terminal) . The DUT 30 can be a component of the user equipment, or vice versa. The RF signal can be a signal according to a communication standard, e.g. a WiFi, a 5G or an LTE signal. The RF signal can be a signal which is generated by the DUT or a response signal from the DUT to a test signal from the measurement device. The RF signal can be a repetitive signal. Fig. 4 shows a schematic diagram of the measurement device 20 according to an embodiment. In particular, Fig. 4 shows a possible autolevel signal chain. The measurement device 20 or more particular its RF front end 21 can comprise a number of components, wherein each component has its own internal impairment parameters (e.g., NF and / or 5 TOI) . These internal impairment parameters of the measurement device 20 can further influence the figure of merit (e.g., EVM) of the device 20. At least some of these internal impairment parameters can be considered when adapting the configuration of the RF front end 21, e.g., by the autolevel 10 algorithm. For instance, the RF front components: a mechanical electrical attenuator, a 15 converter (ADC). end 21 can comprise the following attenuator, a preamplifier, an mixer and an analog-to-digital Fig. 5 shows a user interface of the measurement device 20 according to an embodiment. This user interface can be shown in a display of the device 20. 20 For example, the user interface allows a user to select for each signal impairment parameter if the parameter should be automatically measured or manually entered. In case of the NF the user can further select if the value of the NF should be 25 retrieved from a former IQNC capture of if a new capture should be carried out.

Claims

1. A method (10) of operating a measurement device (20), in particular a signal and / or spectrum analyzer, comprising:connecting (11) a device-under-test, DUT 30, to an RF front end (21) of the measurement device (20);receiving and / or measuring (12) one or more signal impairment parameters of the DUT (30) and / or of a user equipment attached to the DUT;adapting (13) a configuration of the RF front end (21) based on at least one of the signal impairment parameters.

2. The method (10) of claim 1, further comprising:receiving (14) an RF signal from the DUT (30) and processing said RF signal with the RF front end (21) based on the adapted configuration.

3. The method (10) of claim 1 or 2, wherein at least one of the signal impairment parameters is received (12) via a user input on a user interface of the measurement device (20).

4. The method (10) of any one of the preceding claims, wherein the signal impairment parameters comprise a third-order-intercept point, TOI, of the DUT (30) and / or the user equipment.

5. The method (10) of any one of the preceding claims, wherein the signal impairment parameters comprise a noise figure, NF, of the DUT (30) and / or the user equipment.

6. The method (10) of claim 5,wherein the NF of the DUT (30) and / or the user equipment is measured (12) by: measuring a total NF of the measurement device (20) and of the DUT (30) and / or the user equipment,5 - measuring or providing the NF of the measurementdevice (20) only, and deriving the NF of the DUT (30) and / or the user equipment from the total NF and from the NF of the measurement device (20).

107. The method (10) of claim 5 or 6, wherein the NF of the DUT (30) and / or the user equipment is measured (12) by means of an I / Q noise cancellation measurement.

158. The method (10) of any one of the preceding claims, wherein at least one of the signal impairment parametersis measured (12) by means of an AM / AM and / or an AM / PM conversion measurement.

209. The method (10) of any one of the preceding claims, wherein the user equipment is de-embedded for measuring at least one signal impairment parameter of the DUT (30).25 10. The method (10) of any one of the preceding claims,further comprising:storing (17) the received and / or measured signal impairment parameters in a memory of the measurement device (20) .3011. The method (10) of any one of the preceding claims, further comprising:displaying (16) the signal impairment parameters and / or anindication if the signal impairment parameters necessitate theadaption (13) of the configuration of the RF front end.

12. The method (10) of any one of the preceding claims, wherein the configuration of the RF front end (21) is adapted (13) to optimize a figure of merit of the measurement device (2 0) .

13. The method (10) of any one of the preceding claims, wherein the configuration of the RF front (21) end comprises an attenuation of the RF front end (21).

14. A measurement device (20), in particular a signal and / or spectrum analyzer, comprising:an RF front end (21) adapted for being connected to a device-under-test, DUT 30;an interface (22) configured to receive and / or a measurement unit (23) configured to measure one or more signal impairment parameters of the DUT (30) and / or of a user equipment attached to the DUT;wherein the RF front end (21) is configured to adapt its configuration based on at least one of the signal impairment parameters .

15. The measurement device (20) of wherein the RF front end (21)RF signal from the DUT (30) and based on the adapted configuration.claim 14,is configured to receive an to process said RF signal16. The measurement device (20) of claim 14 and 15wherein the interface (22) comprises a user interface configured to receive at least one of the signal impairment parameters via a user input.

17. The measurement device (20) of any one of claims 14 to 16, wherein the measurement unit (23) is configured to carry out5 - an I / Q noise cancellation measurement, and / oran AM / AM and / or an AM / PM conversion measurement to determine at least one of the signal impairment parameters .

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