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.

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.]. .Iadd.a .Iaddend.broadband measurement signal into .[.at least two.]. .Iadd.a plurality of .Iaddend.subband measurement signals; displacing, by a signal alignment circuit, the .[.at least two.]. subband measurement signals to correspond with respective frequency bands of .[.the.]. .Iadd.a .Iaddend.reference signal.[., wherein the displacement is performed with the use of an external trigger signal.].; .[.and reconstructing,.]. .Iadd.generating, .Iaddend.by a signal reconstruction circuit, .[.the at least two subband measurement signals to form.]. a reconstructed .[.broadband.]. measurement signal .Iadd.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.Iaddend..

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.]. .Iadd.displacing .Iaddend.step comprises correlating .Iadd.each of .Iaddend.the subband measurement signals with .Iadd.a corresponding frequency band of .Iaddend.the reference signal.

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

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

7. The method according to claim 1, wherein the .[.displacement.]. .Iadd.displacing .Iaddend.step is .[.implemented within a.]. .Iadd.performed in the .Iaddend.frequency-modulation domain.[.of 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.]. .Iadd.displacing .Iaddend.step is .[.implemented in an I/Q baseband of the subband measurement signals.]. .Iadd.performed in the I/Q domain.Iaddend..

10. The method according to claim 9, wherein the .[.reconstruction.]. step .Iadd.of generating a reconstructed measurement signal .Iaddend.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.]. .Iadd.measurement error .Iaddend.correction of a deviation error after the .[.reconstruction.]. step .Iadd.of generating a reconstructed measurement signal.Iaddend..

12. A measuring device .[.for the analysis of a broadband measurement signal,.]. comprising: a signal subdividing component configured to subdivide .[.the.]. .Iadd.a .Iaddend.broadband measurement signal into .[.at least two.]. .Iadd.a plurality of .Iaddend.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 .Iadd.a .Iaddend.corresponding .[.reference-signal frequency bands.]. .Iadd.frequency band .Iaddend.of a reference signal.[., wherein the displacement is performed with the use of an external trigger signal.].; .Iadd.and .Iaddend. a signal reconstructing component configured to .[.reconstruct.]. .Iadd.generate a reconstructed broadband measurement signal based on .Iaddend.the displaced subband measurement signals.[.to form a reconstructed broadband measurement signal.]..Iadd., wherein the generation of the reconstructed measurement signal is performed with the use of an external trigger signal.Iaddend.; and .[.a signal analysis component.]. .Iadd.wherein the measuring device is .Iaddend.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.]. .Iadd.wherein the measuring device is .Iaddend.configured to determine a number of .[.measurement-signal.]. .Iadd.measurement signal .Iaddend.frequency bands dependent upon the bandwidth of the .[.received.]. .Iadd.broadband .Iaddend.measurement signal, and to increase the number of .[.measurement-signal.]. .Iadd.measurement signal .Iaddend.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.

.Iadd.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..Iaddend.

.Iadd.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..Iaddend.

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

.Iadd.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..Iaddend.

.Iadd.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..Iaddend.

.Iadd.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..Iaddend.

.Iadd.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..Iaddend.

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

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

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

.Iadd.26. The method according to claim 20, further comprising: demodulating the subband measurement signals by a demodulator..Iaddend.

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

.Iadd.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..Iaddend.

.Iadd.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..Iaddend.

.Iadd.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..Iaddend.

.Iadd.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..Iaddend.

.Iadd.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..Iaddend.

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

.Iadd.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..Iaddend.

.Iadd.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..Iaddend.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other features, aspects and advantages of the present invention are explained in greater detail with reference to the Figures of the drawings, wherein the Figures illustrate exemplary embodiments of the invention. Identical components in the Figures are provided with identical reference numbers. Accordingly, embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying, in which:

(2) FIG. 1 shows a block diagram of an approach for the averaging of a measurement-signal deviation, in accordance with example embodiments of the invention;

(3) FIG. 2 shows a block diagram of a further approach for the averaging of a measurement-signal deviation, in accordance with example embodiments of the invention;

(4) FIG. 3 shows a block diagram of an alternative approach to that shown in FIG. 2;

(5) FIG. 4a shows a block diagram of a subdivision unit according to an example embodiment of the invention;

(6) FIG. 4b shows a transmission characteristic of the subdivision unit illustrated in FIG. 4a;

(7) FIG. 5 shows a block diagram of a frequency demodulator according to an example embodiment of the invention;

(8) FIG. 6 shows a block diagram of an alignment unit in the I/Q baseband according to an example embodiment of the invention;

(9) FIG. 7 shows a block diagram of an alignment unit in the FM baseband according to an example embodiment of the invention;

(10) FIG. 8 shows a block diagram of a reconstruction unit in the I/Q domain according to an example embodiment of the invention;

(11) FIG. 9 shows a block diagram of a reconstruction unit in the FM domain according to an example embodiment of the invention;

(12) FIG. 10 shows a broadband measurement signal with reference signal according to an example embodiment of the invention;

(13) FIG. 11a shows a frequency band after the demodulation according to an example embodiment of the invention;

(14) FIG. 11b shows the demodulated frequency band illustrated in FIG. 11a after a filtering;

(15) FIG. 12a shows an external trigger signal according to an example embodiment of the invention;

(16) FIG. 12b shows a subdivision of the broadband measurement signal into three frequency bands according to an example embodiment of the invention; and

(17) FIG. 12c shows a reconstructed broadband measurement signal according to an example embodiment of the invention.

DETAILED DESCRIPTION

(18) FIG. 1 shows a block diagram of an approach for the averaging of a measurement-signal deviation, in accordance with example embodiments of the invention. In this context, a broadband measurement signal RF.sub.in is connected to an input of a subdivision unit 1. Several frequency bands RF.sub.sub of the measurement signal RF.sub.in are supplied to the output of the subdivision unit 1. These measurement-signal frequency bands RF.sub.sub are supplied to an alignment unit 2. Displaced measurement-signal frequency bands RF.sup.sub,t are provided at the output of the alignment unit 2. These measurement-signal frequency bands RF.sub.sub,t are supplied to a reconstruction unit 3. A broadband reconstructed measurement signal RF.sub.recon is provided at the output of the reconstruction unit 3. The broadband combined measurement signal RF.sub.recon is supplied to an evaluation unit 4. A deviation signal ε between the measurement signal RF.sub.in and the reference signal RF.sub.ref is provided at the output of the evaluation unit 4. The reference signal RF.sub.ref required for this purpose is made available to the evaluation unit 4 or generated there.

(19) With further reference to FIG. 1, a broadband measurement signal is split into a plurality of frequency sub-bands RF.sub.sub. As a result of the subdivision, a measuring device, especially a signal analyzer, with a relatively smaller resolution bandwidth than the bandwidth of the measurement signal RF.sub.in can be used to determine the deviation ε between the measurement signal RF.sub.in and the reference signal RF.sub.ref. With regard to radar measurement signals, the deviation error ε occurs within the KHz range, while the bandwidth of the measurement signal RF.sub.in amounts to several GHz. .Iadd.According to a further embodiment, the measuring device provides a unit for determining the number of measurement-signal frequency bands (RF.sub.sub) depending on the bandwidth (B) of the received measurement signal (RF.sub.in), and the unit increases the number of measurement-signal frequency bands with increasing bandwidth..Iaddend.

(20) FIG. 2 shows a block diagram of a further approach for the averaging of a measurement-signal deviation, in accordance with example embodiments of the invention. The illustration according to FIG. 2 shows a method or respectively a measuring device according to the invention which operates in an I/Q domain. Such In-Phase/Quadrature phase signals are used in a standardized manner in measuring devices. In order to obtain a transformation from the I/Q domain into a frequency domain, a demodulator 5, which is presented in greater detail in FIG. 5, is introduced, as shown in FIG. 2, between the subdivision unit 1 and the alignment unit 2. Following this, the alignment unit 2 and the reconstruction unit 3 can determine the reconstructed measurement signal RF.sub.recon with simple mathematical operations, especially addition, in order to provide the alignment error ε.

(21) As an alternative to FIG. 2, FIG. 3 shows a block diagram of an alternative approach to that shown in FIG. 2. By way of difference from FIG. 2, the demodulation unit 5 is introduced between the reconstruction unit 3 and the evaluation unit 4. As shown in the exemplary embodiment of FIG. 3, the subdivision unit 1 provides the measurement signal RF.sub.in in the measurement-signal frequency bands RF.sub.sub in the I/Q domain. According to FIG. 3, the I/Q data provided in this manner are made directly available to the alignment unit 2 and the reconstruction unit 3.

(22) Accordingly, FIGS. 1 to 3 show exemplary embodiments for the subdivision of a broadband measurement signal RF.sub.in. For this purpose, a combined, broadband measurement signal RF.sub.recon, which is compared with a reference signal RF.sub.ref, is supplied, on the one hand, to the evaluation unit 4. The comparison can be determined by subtracting the reference signal RF.sub.ref from the combined broadband measurement signal RF.sub.recon, wherein the deviation error ε is then displayed directly. As an alternative, the evaluation unit 4 is a display element of a measuring device which merely displays the signals RF.sub.recon and RF.sub.ref. The deviation ε can then be inferred by means of appropriate evaluation algorithms.

(23) FIG. 4a shows a block diagram of a subdivision unit 1 according to an example embodiment of the invention. The measurement signal RF.sub.in connected at the input of the subdivision unit 1 is subdivided into three frequency bands I/Q.sub.1, I/Q.sub.2 and I/Q.sub.3. In this context, the bandwidth of each frequency sub-band I/Q.sub.1, I/Q.sub.2 and I/Q.sub.3 is smaller than the analysis bandwidth of the measuring device.

(24) According to FIG. 4a, the RF.sub.in is mixed in a mixing unit 6 with a first carrier frequency ω.sub.1. Following this, the part of the spectrum of the measurement signal RF.sub.in which is not to be a part of the frequency sub-band I/Q.sub.1 is removed via a filter element 7, especially a band-pass filter. Following this, the baseband signal obtained is digitized in an analog/digital converter 8 and supplied to an I/Q modulator 9. At the output of the I/Q modulator 9, a frequency sub-band I/Q.sub.1 is obtained. The respective frequency sub-band is then present as so-called I/Q data and is designated in the following as an I/Q.sub.1 signal.

(25) The two other frequency bands I/Q.sub.2, and I/Q.sub.3 are mixed respectively by mixing the input signal RF.sub.in with a second carrier frequency ω.sub.2 or a third carrier frequency ω.sub.3. Accordingly, frequency sub-bands are obtained at the output as I/Q data.

(26) FIG. 4b shows a transmission characteristic of the sub-division unit 1 shown in FIG. 4a. In this context, the broadband signal RF.sub.in is drawn as a continuous line. The signal RF.sub.in is subdivided into three sub-bands RF.sub.sub1 to RF.sub.sub3 corresponding to the carrier frequencies ω1, ω2, ω3, which are each illustrated as dashed lines. These sub-bands RF.sub.sub are further processed by the mixer units 6 as baseband signals. The filtering necessary for this purpose is implemented by the filter element 7.

(27) The selection of the number of frequency bands takes place within the measuring device itself. In this context, the resolution bandwidth of the measuring device and the bandwidth B of the measurement signal are critical. The broader the bandwidth of the measurement signal RF.sub.in, the more frequency bands are necessary in order to perform a signal analysis with a suitable resolution, especially in the KHz range.

(28) FIG. 5 shows a block diagram of a demodulation unit 5 according to an example embodiment of the invention. With further reference to FIG. 2 and FIG. 3, this provides for the conversion of frequency bands which are present as an I/Q signal, as shown, for example, in FIG. 4a, into frequency bands in the FM domain. In general, for a phase-invariant signal x(t) with amplitude A
x(t)=A.Math.e.sup.jφ(t)

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

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

(31) For a time-discrete signal, the following applies:
x[n].Math.x*[n−1].fwdarw.|λ.sup.2|e.sup.j[φ[n]−φ[−1]]

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

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

(34) Accordingly, in the case of the supplied signals I/Q.sub.1 to I/Q.sub.3, 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.sub.

(35) 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.sub.ref corresponding to the respective frequency band. In order to obtain such a reference frequency band I/Q.sub.ref, the reference signal RF.sub.ref is modulated by means of a frequency modulator 21 and bandwidth limited by means of filter elements 7.

(36) Through the correlators 22, the corresponding reference bands I/Q.sub.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.sub.recon.

(37) The respective time displacements t.sub.1 to t.sub.3 and also the carrier frequencies f.sub.1 to f.sub.3 can be picked up at the output of the alignment unit 2. The carrier frequencies f.sub.1 to f.sub.3 correspond to the carrier frequencies ω.sub.1, ω.sub.2 and ω.sub.3 of the subdivision unit 1.

(38) FIG. 7 shows a block diagram of .[.a reconstruction unit 3.]. .Iadd.an alignment unit 2 .Iaddend.(e.g., for the exemplary embodiment shown in FIG. 2) according to an example embodiment of the invention. In this context, each of the frequency sub-band FM.sub.1 to FM.sub.3 are correlated with a reference signal sub-band FM.sub.ref1 to FM.sub.ref3 corresponding to the frequency sub-band FM.sub.1 to FM.sub.3. At the output of the alignment unit 2, corresponding to FIG. 6, the parameters t.sub.1 to t.sub.3 and the frequencies f.sub.1 to f.sub.3 are supplied as parameters to the reconstruction unit. The carrier frequencies f.sub.1 to f.sub.3 correspond to the carrier angular frequencies ω.sub.1, ω.sub.2, and ω.sub.3 of the subdivision unit 1.

(39) It is evident that the reconstruction unit 2 according to FIG. 7 can be realized more simply than the reconstruction unit 2 according to FIG. 6, since a modulation of the reference signal RF.sub.ref need not be implemented in the I/Q domain, which leads to a simplification if the reference signal RF.sub.ref is present in the FM domain.

(40) FIG. 8 shows a block diagram of a reconstruction unit 3 according to an example embodiment of the invention. In this context, I/Q signals according to the exemplary embodiment from FIG. 3 are connected to the input of the reconstruction unit 3. Additionally, the time delays t and carrier frequencies f determined according to the alignment unit 2 are supplied to the reconstruction unit 3 for each I/Q signal.

(41) In this context, each I/Q signal I/Q.sub.1 to I/Q.sub.3 is supplied to a time delay unit 31 in order to reconstruct a determined time delay of the measurement signal RF.sub.in in a time-corrected manner. After the time displacement of the respective signal I/Q.sub.1 to I/Q.sub.3 by means of a mixer unit 6, the respective I/Q signal is displaced into the corresponding frequency domain of the measurement signal RF.sub.in. Finally, all of the displaced signals are combined by means of an adding unit 33. At the output of the reconstruction unit 3, a broadband reconstructed I/Q signal is generated.

(42) As an alternative to FIG. 8, FIG. 9 shows a block diagram of a reconstruction unit 3 (e.g., for the exemplary embodiment according to FIG. 2) according to an example embodiment of the invention. In this context, FM signals according to the exemplary embodiment from FIG. 2 are connected to the input of the reconstruction unit 3. Additionally, the time delays t determined according to the alignment unit 2 and carrier frequencies f used according to the splitter unit 1 are supplied to the reconstruction unit 3 for each FM signal.

(43) The frequency bands FM.sub.1 to FM.sub.3 supplied at the input of the reconstruction unit 3 are displaced via a time displacement unit 31 and a frequency adding unit 32 to the corresponding positions of the measurement signal RF.sub.in. Following the time displacement and frequency displacement, an addition of all frequency bands is implemented by means of the adding unit 33. A broadband reconstructed measurement signal RF.sub.recon is generated at the output of the reconstruction unit 3.

(44) FIG. 10 shows a period of a broadband measurement signal RF.sub.in used according to example embodiments of the invention, as utilized, for example, in radar systems. In this context, the change in the frequency f is shown dependent upon the time t. Such measurement signals RF.sub.in are also designated as partially linear-frequency-modulated signals. They are characterized by their parameterization. In this context, the number of segments in which the frequency of the measurement signal RF.sub.in is constant or linear-variant is a first parameter. According to FIG. 10, four segments are provided which each have a characteristic segment duration T.sub.1 to T.sub.4.

(45) A second parameter is the start time to at which a period of the measurement signal RF.sub.in begins. A frequency offset f.sub.0 is provided as a third parameter. Similarly, the maximal frequency f.sub.2, or respectively, on the basis of the characteristic shown, also the frequency f.sub.3, is characteristic for such a measurement signal RF.sub.in as a fourth parameter.

(46) The illustrated signal can be described mathematically as follows:

(47) $\mathrm{FM}\left(t\right)=\underset{n=1}{\overset{N}{.Math.}}\left(\left(\frac{f_n-f_{n-1}}{T_n}\right).Math.\left(t-t_n\right)+f_{n-1}\right).Math.g\left(t-t_n;T_n\right)f\stackrel{.Math.}{u}\mathrm{rt}ϵ\left[t_0,t_N\right]$
where the symbols denote:

(48) TABLE-US-00001 f.sub.n: end frequency of a segment n t.sub.N: time offset per segment n t.sub.0: time offset before segment 1 T.sub.N: time duration of the n-th segment N: number of segments N: n-th segment G(T; T.sub.N): window function

(49) A signal RF.sub.ref is now transmitted from a transmitter, and a corresponding broadband measurement signal RF.sub.in—illustrated with a dashed line in FIG. 10—is received. In this context, the received measurement signal RF.sub.in provides a time delay d and an offset V of the amplitude relative to the reference signal RF.sub.ref. The time delay d in this context corresponds to the distance between an object and the transmitter. The amplitude offset V in this context corresponds to the relative velocity between the transmitter and the object.

(50) The measurement signals RF.sub.in and RF.sub.ref shown in FIG. 10 provide a different linear gradient of the frequencies in segment T.sub.2 and segment T.sub.4. These different gradients allow an improved evaluation of the distance and the velocity of the detected object.

(51) In order to determine the quality of a radar system, a reference signal RF.sub.ref is compared with the measurement signal RF.sub.in in a measuring device. The enlarged region illustrated in FIG. 10 shows that the received measurement signal RF.sub.in is slightly wave-like and differs by comparison with the transmitted reference signal RF.sub.ref by a deviation factor E. This deviation ε is the error of the radar system and must be determined. The deviation ε is generally a few kilohertz.

(52) The frequency modulation of the measurement signal varies between the frequencies f.sub.1 and f.sub.2, which corresponds to a bandwidth B of the measurement signal. The bandwidth B of such a measurement signal RF.sub.in is typically 2 GHz. In order to detect the small deviation error E, a correspondingly well resolved measuring device and the use of the method according to the invention are required.

(53) FIG. 11a shows a frequency band (e.g., obtained according to FIG. 2) after the demodulator 5. In this context, regions which are not included by the frequency band in the context of the subdivision, are added to the signal as noise. Such noise is undesirable and is therefore filtered out before the balancing in the alignment unit 2 and the reconstruction in the reconstruction unit 3. A correspondingly filtered signal is shown according to FIG. 11b.

(54) FIG. 12a shows an external trigger signal T.sub.ext according to an example embodiment of the invention. This trigger signal T.sub.ext comprising Dirac impulses indicates the beginning of every period of the measurement signal RF.sub.in. In particular, this trigger signal T.sub.ext is useful for the reconstruction of the aligned signal in the reconstruction unit 3. Each Dirac impulse of the trigger signal T.sub.ext indicates the beginning of a new period of the measurement signal RF.sub.in in the reconstruction unit 3. Through the external trigger signal T.sub.ext, the measurement time duration for the determination of the deviation ε can be enormously reduced, since the individual frequency bands can be positioned more simply on the basis of the trigger signal T.sub.ext. In this case, an effort-intensive correlation is not required.

(55) FIG. 12b shows a measurement signal RF.sub.in split in three frequency bands according to an example embodiment of the invention. In this context, the bandwidth B is subdivided by means of the measuring device into three frequency bands B.sub.sub1 to B.sub.sub3. These frequency bands overlap and, in total, provide a relatively larger bandwidth than the bandwidth B of the measurement signal. This balances the frequency offset V between the reference signal RF.sub.ref and the measurement signal RF.sub.in, and balances the offset for reconstruction the individual frequency bands.

(56) The frequency bands obtained in this manner are combined after time-critical and frequency-critical alignment by means of the alignment unit 1 to form the reconstructed measurement signal RF.sub.recon, as illustrated in FIG. 12c.

(57) FIG. 12c shows a broadband reconstructed measurement signal RF.sub.recon. In this context, it is evident that a time offset between the individual frequency bands had to be balanced. By means of the correlators 22 of the alignment unit 2, the frequency of each corresponding frequency band RF.sub.sub relative to the measurement signal RF.sub.in was determined and correctly positioned. The accordingly combined measurement signal RF.sub.recon provides a deviation ε which is illustrated in the form of a non-linearity of the measurement signal. This nonlinearity represents the deviation factor ε of the radar system.

(58) The nonlinearity shown in FIG. 12c is illustrated in an exaggerated manner. Through subtraction of the reference signal RF.sub.ref from the combined reconstructed signal RF.sub.recon, a deviation signal ε is obtained. The measurement signal RF.sub.in is periodic. Because of the digital character, all periods of the measurement signal RF.sub.in can be supplied sequentially to the subdivision unit 1. Video filters are used to reduce a background noise of the measuring device which would lead to an additional deterioration of the reconstructed signal RF.sub.recon. The video filters are arranged after the frequency demodulation 5.

(59) As an alternative, an averaging of the measurements over a plurality of periods of the measurement signal RF.sub.in, also designated as a Trace Averaging, is implemented in order to reduce the background noise. These several periods of the measurement signal RF.sub.in are averaged to form one period. An average value of the period of the measurement signal RF.sub.in is obtained, thereby reducing major nonlinearities of the measurement signal. The average formation is implemented after the reconstruction of the signal RF.sub.recon and before the evaluation.

(60) A correlation is advantageous, because a noise of the signal must be calculated out in order to find the frequency threshold value. This is obtained, for example, by correlation with the reference signal.

(61) As an alternative to the analysis of the I/Q signals as shown in FIG. 2 or the FM signals as shown in FIG. 3, a phase-modulated signal can also be analyzed. For a phase-modulated signal, the following applies:
φ(t)=∫ω(t)dt

(62) From the partially linear regions of the measurement signal RF.sub.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).

(63) 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.sub.in with six periods must therefore be analyzed.

(64) 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.