Method and a measuring device for measuring broadband measurement signals

Abstract

The invention relates to a method for determining a deviation of a broadband measurement signal from a reference signal. The method provides the steps: subdivision of the signal into at least two measurement-signal frequency bands; displacement of the measurement-signal frequency bands; and reconstruction of the at least two measurement-signal frequency bands. A corresponding measurement device is also contained within the idea of the invention.

Description

PRIORITY

The present application According to a further embodiment, the measuring device provides a unit for determining the number of measurement-signal frequency bands (RF_sub) depending on the bandwidth (B) of the received measurement signal (RF_in), and the unit increases the number of measurement-signal frequency bands with increasing bandwidth.

The angular frequency ω is the time derivation of the phase φ:

$\omega \left(t\right)=\frac{\partial }{\partial t}\phi \left(t\right)$

For a time-discrete signal, the following applies:
x[n]·x*[n−1]→|λ²|e^{j[φ[n]−φ[−1]]}

In the case of time-discrete signals, the following applies for the phase φ:

$\phi =\mathrm{arc}\tan \left(\frac{Q}{I}\right)$
wherein I denotes the in-phase component and Q denotes the quadrature-phase component of the respective I/Q signal.

Accordingly, in the case of the supplied signals I/Q₁ to I/Q₃, the phase of value φ is determined from phase differences Δφ and arctan calculation between two successive sampled values of the I/Q signal in the phase unit 51. The result from the phase unit 51 is then supplied to the differentiator 52, which determines the derivation of the phase according to the above relationship. Accordingly, through the derivation of the phase information of the respective I/Q signal, a signal is transferred into the frequency domain. A differentiator 52 is produced especially by means of an ideal high-pass or by means of a high-pass which is linear at least for the sub-range necessary for the frequency domain of the sub-band RF_sub.

FIG. 6 shows a block diagram of an alignment unit 2 according to an example embodiment of the invention. According to FIG. 6, I/Q signals according to the exemplary embodiment from FIG. 3 are connected to the input of the alignment unit 2. By means of a correlator 22, the corresponding I/Q signal is correlated with a reference frequency band I/Q_ref corresponding to the respective frequency band. In order to obtain such a reference frequency band I/Q_ref, the reference signal RF_ref is modulated by means of a frequency modulator 21 and bandwidth limited by means of filter elements 7.

Through the correlators 22, the corresponding reference bands I/Q_ref are compared with the respective I/Q signals in order to determine the corresponding time constant t and the corresponding carrier frequency f. The time constant t and the carrier frequency f are necessary in order to combine the I/Q signals (baseband signals) in the correct sequence and with the correct time succession in the reconstruction unit 3 to form the reconstructed signal RF_recon.

The respective time displacements t₁ to t₃ and also the carrier frequencies f₁ to f₃ can be picked up at the output of the alignment unit 2. The carrier frequencies f₁ to f₃ correspond to the carrier frequencies ω₁, ω₂ and ω₃ of the subdivision unit 1.

FIG. 7 shows a block diagram of

From the partially linear regions of the measurement signal RF_in, portions with quadratic regions are formed. The alignment of frequency bands as PM signals can also be implemented by means of correlation. The offset and time delay can also be determined by means of a maximum likelihood analysis (English: maximum likelihood).

Within the subdivision into frequency sub-bands, the use of at least two periods of the measurement signal is indispensable in order to balance the time offset in the analysis and to display a full period of the measurement signal. In the case of three frequency bands and sequential processing, a measurement signal RF_in with six periods must therefore be analyzed.

Within the scope of the invention, all of the elements described and/or illustrated and/or claimed can be combined arbitrarily with one another. For example, a combination of the two exemplary embodiments according to FIG. 2 and FIG. 3 is not excluded. Further, in the preceding specification, various embodiments have been described with reference to the accompanying drawings. It will, however, be evident that various modifications may be made thereto, and additional embodiments may be implemented, without departing from the broader scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.

Claims

1. A method for determining a deviation of a broadband measurement signal from a reference signal, comprising:

subdividing, by a signal subdividing circuit, the a broadband measurement signal into at least two a plurality of subband measurement signals;

displacing, by a signal alignment circuit, the at least two subband measurement signals to correspond with respective frequency bands of the a reference signal, wherein the displacement is performed with the use of an external trigger signal; and

reconstructing, generating, by a signal reconstruction circuit, the at least two subband measurement signals to form a reconstructed broadband measurement signal based on the displaced subband measurement signals, wherein the generation of the reconstructed measurement signal is performed with the use of an external trigger signal; and

analyzing the reconstructed measurement signal relative to the reference signal, wherein a deviation of the reconstructed measurement signal relative to the reference signal is used as a value for performing an error determination.

2. The method according to claim 1, wherein the broadband measurement signal is a periodic frequency-modulated signal, and wherein a period of the signal is at least partially linear-frequency-modulated.

3. The method according to claim 1, further comprising one or more of the steps of:

subtracting the reference signal from the reconstructed broadband measurement signal; and

displaying the reconstructed broadband measurement signal with the reference signal.

4. The method according to claim 1, wherein the displacement displacing step comprises correlating each of the subband measurement signals with a corresponding frequency band of the reference signal.

5. The method according to claim 1, wherein the displacement subdividing step is implemented with the use of a carrier signal.

6. The method according to claim 1, wherein the reconstruction step of generating a reconstructed measurement signal comprises adding the displaced subband measurement signals.

7. The method according to claim 1, wherein the displacement displacing step is implemented within a performed in the frequency-modulation domainof the subband measurement signals.

8. The method according to claim 7, further comprising:

demodulating the broadband measurement signal divided into the at least two subband measurement signals.

9. The method according to claim 1, wherein the displacement displacing step is implemented in an I/Q baseband of the subband measurement signals performed in the I/Q domain.

10. The method according to claim 9, wherein the reconstruction step of generating a reconstructed measurement signal comprises:

time displacing each of the subband measurement signals by a time offset of the measurement signal corresponding to the reference signal;

mixing each of the time-displaced subband measurement signals with a frequency-band carrier corresponding to the reference signal frequency band;

adding the mixed subband measurement signals; and

demodulating the mixed subband measurement signals to form a reconstructed broadband measurement signal.

11. The method according to claim 1, further comprising:

performing a measurement-error measurement error correction of a deviation error after the reconstruction step of generating a reconstructed measurement signal.

12. A measuring device for the analysis of a broadband measurement signal, comprising:

a signal subdividing component configured to subdivide the a broadband measurement signal into at least two a plurality of subband measurement signals, wherein each subband measurement signal comprises an I/Q baseband signal;

a signal displacing component configured to displace each of the subband measurement signals relative to a corresponding reference-signal frequency bands frequency band of a reference signal, wherein the displacement is performed with the use of an external trigger signal; and

a signal reconstructing component configured to reconstruct generate a reconstructed broadband measurement signal based on the displaced subband measurement signalsto form a reconstructed broadband measurement signal, wherein the generation of the reconstructed measurement signal is performed with the use of an external trigger signal; and

a signal analysis component wherein the measuring device is configured to analyze the reconstructed broadband measurement signal relative to the reference signal, wherein a deviation of the reconstructed broadband measurement signal relative to the reference signal is provided as a starting value for the measuring device at which a period of the measurement signal begins.

13. The measuring device according to claim 12, further comprising:

a processor component wherein the measuring device is configured to determine a number of measurement-signal measurement signal frequency bands dependent upon the bandwidth of the received broadband measurement signal, and to increase the number of measurement-signal measurement signal frequency bands with increasing bandwidth.

14. The measuring device according to any one of claim 12, further comprising:

a selection component configured to select a measurement period length of the broadband measurement signal.

15. The measuring device according to claim 12, further comprising:

a noise reduction component configured to filter and/or average the reconstructed broadband measurement signal in order to reduce background noise of the measuring device.

16. A method comprising:

subdividing, by a signal subdividing component, a broadband measurement signal into a plurality of subband measurement signals, wherein the broadband measurement signal is a modulated broadband signal;

displacing, by a signal displacing component, the subband measurement signals to correspond with respective frequency bands of a reference signal;

generating, by a signal reconstructing component, a reconstructed measurement signal based on the displaced subband measurement signals using a trigger signal; and

analyzing the reconstructed measurement signal relative to the reference signal, wherein a deviation of the reconstructed measurement signal relative to the reference signal is used as a value for performing an error determination.

17. The method according to claim 16, wherein the reconstructed measurement signal is created by summing a measurement value computed individually for at least two subbands of the subband measurement signals to calculate an aggregated measurement value across the at least two subbands.

18. The method according to claim 16, wherein the subband measurement signals together comprise substantially all of the bandwidth of the broadband measurement signal.

19. The method according to claim 16, further comprising one or more of the steps of:

subtracting the reference signal from the reconstructed measurement signal by an evaluation unit; and

displaying the reconstructed measurement signal with the reference signal by the evaluation unit.

20. The method according to claim 16, further comprising:

comparing the subband measurement signals with the corresponding subbands of the reference signal to determine a deviation factor reflected by the measurement signal.

21. The method according to claim 16, further comprising the steps of:

using the reference signal and the reconstructed broadband measurement signal to determine quality measurements.

22. The method according to claim 16, wherein the displacing step comprises correlating each of the subband measurement signals with a corresponding frequency band of the reference signal by a correlator.

23. The method according to claim 16, wherein the subdividing step is implemented with the use of a carrier signal.

24. The method according to claim 16, wherein the step of generating a reconstructed measurement signal comprises adding the displaced subband measurement signals.

25. The method according to claim 16, wherein the displacing step is performed in the frequency-modulation domain.

26. The method according to claim 20, further comprising:

demodulating the subband measurement signals by a demodulator.

27. The method according to claim 16, wherein the displacing step is performed in the I/Q domain.

28. The method according to claim 16, wherein the step of generating a reconstructed measurement signal comprises:

time displacing each subband measurement signal by a time offset of the measurement signal corresponding to the reference signal;

mixing each time-displaced subband measurement signal with a frequency-band carrier corresponding to the reference signal frequency band;

adding the mixed measurement signal frequency bands; and

demodulating the resulting summed mixed subband measurement signal to form a reconstructed broadband measurement signal.

29. The method according to claim 16, further comprising:

performing a measurement error correction of a deviation error after the step of generating a reconstructed measurement signal.

30. A measuring device comprising:

a signal subdividing component configured to subdivide a broadband measurement signal into a plurality of subband measurement signals, wherein each subband measurement signal comprises an I/Q signal;

a signal displacing component configured to displace each of the subband measurement signals relative to a corresponding frequency band of a reference signal; and

a signal reconstructing component configured to generate a reconstructed measurement signal by combining the subband measurement signals using a trigger signal; and

wherein the measuring device is configured to analyze the reconstructed measurement signal relative to the reference signal, wherein a deviation of the reconstructed measurement signal relative to the reference signal is used as a value for performing an error determination.

31. The measuring device according to claim 30, wherein the measuring device is configured to determine a number of measurement signal frequency bands dependent upon the bandwidth of the broadband measurement signal, and to increase the number of measurement frequency bands with increasing bandwidth.

32. The measuring device according to claim 30, further comprising:

a noise reduction component configured to filter and/or average the reconstructed broadband measurement signal in order to reduce background noise of the measuring device.

33. The measuring device according to claim 30, wherein the correlator is configured to correlate the subband measurement signals with the reference signal.

34. The measuring device according to claim 30, wherein the reconstructing component is configured to reconstruct the subband measurement signals to form a reconstructed broadband measurement signal.

35. The measuring device according to claim 30, wherein the reconstructing component is configured to create the aggregated measurement by summing a measurement value computed for at least two subbands to calculate the measurement value across the at least two subbands.