Impact of Frequency Ramp Nonlinearity, Phase Noise, and SNR on FMCW Radar Accuracy

Ayhan, Serdal; Scherr, Steffen; Bhutani, Akanksha; Fischbach, Benjamin; Pauli, Mario; Zwick, Thomas

doi:10.1109/tmtt.2016.2599165

Cited by 105 publications

(37 citation statements)

References 15 publications

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“…The measured SNR and SNDR of both 60 GHz and 122 GHz FMCW radars was relatively high (50 dB) and hence the FMCW ramp nonlinearities were practically negligible in this scenario. In addition, the frequency-estimation method is followed by the phase-estimation method (i.e., a time-domain correlation method), which further improves the range estimation accuracy [3]. The radar measurement results shown in Figure 8, Figure 9, Figure 10 and Figure 11 are discussed below.…”

Section: Resultsmentioning

confidence: 99%

“…In [2], a high-accuracy 24 GHz FMCW radar is used to detect the position of a piston in a hydraulic cylinder. Further, the influence of FMCW ramp signal parameters, including ramp nonlinearity, phase noise and signal-to-noise ratio (SNR) on the distance measurement accuracy of a 24 GHz FMCW radar is investigated in [3] and the influence of a target’s geometry and position on the accuracy of a broadband 80.5 GHz FMCW radar is shown in [4]. The majority of these and several other papers published in this field are based on FMCW radars operating below 100 GHz.…”

Section: Introductionmentioning

confidence: 99%

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The Role of Millimeter-Waves in the Distance Measurement Accuracy of an FMCW Radar Sensor

Bhutani

Marahrens

Gehringer

et al. 2019

Sensors

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High-accuracy, short-range distance measurement is required in a variety of industrial applications e.g., positioning of robots in a fully automated production process, level measurement of liquids in small containers. An FMCW radar sensor is suitable for this purpose, since many of these applications involve harsh environments. Due to the progress in the field of semiconductor technology, FMCW radar sensors operating in different millimeter-wave frequency bands are available today. An important question in this context, which has not been investigated so far is how does a millimeter-wave frequency band influence the sensor accuracy, when thousands of distance measurements are performed with a sensor. This topic has been dealt with for the first time in this paper. The method used for analyzing the FMCW radar signal combines a frequency- and phase-estimation algorithm. The frequency-estimation algorithm based on the fast Fourier transform and the chirp-z transform provides a coarse estimate of the target distance. Subsequently, the phase-estimation algorithm based on a cross-correlation function provides a fine estimate of the target distance. The novel aspects of this paper are as follows. First, the estimation theory concept of Cramér-Rao lower bound (CRLB) has been used to compare the accuracy of two millimeter-wave FMCW radars operating at 60 GHz and 122 GHz. In this comparison, the measurement parameters (e.g., bandwidth, signal-to-noise ratio) as well as the signal-processing algorithm used for both the radars are the same, thus ensuring an unbiased comparison of the FMCW radars, solely based on the choice of millimeter-wave frequency band. Second, the improvement in distance measurement accuracy obtained after each step of the combined frequency- and phase-estimation algorithm has been experimentally demonstrated for both the radars. A total of 5100 short-range distance measurements are made using the 60 GHz and 122 GHz FMCW radar. The measurement results are analyzed at various stages of the frequency- and phase-estimation algorithm and the measurement error is calculated using a nanometer-precision linear motor. At every stage, the mean error values measured with the 60 GHz and 122 GHz FMCW radars are compared. The final accuracy achieved using both radars is of the order of a few micrometers. The measured standard deviation values of the 60 GHz and 122 GHz FMCW radar have been compared against the CRLB. As predicted by the CRLB, this paper experimentally validates for the first time that the 122 GHz FMCW radar provides a higher repeatability of micrometer-accuracy distance measurements than the 60 GHz FMCW radar.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Role of Millimeter-Waves in the Distance Measurement Accuracy of an FMCW Radar Sensor

Bhutani

Marahrens

Gehringer

et al. 2019

Sensors

Self Cite

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“…However, the actual range resolution is degraded due to non-ideal factors in FMCW radar. Non-ideal factors include the reduced effective modulation bandwidth due to timeof-flight delays, the increased main-lobe null-to-null bandwidth when FFT windows are applied, and non-linearity of frequency sweeps [3,4,5]. Various studies have been reported to improve range resolution, such as increasing bandwidth [6], using triangular sweep signal [7], over-sampling [8], and removing aliasing effects [9].…”

Section: Introductionmentioning

confidence: 99%

Method to improve degraded range resolution due to non-ideal factors in FMCW radar

Won

Shin

Jung

et al. 2019

IEICE Electron. Express

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This paper reports a method to improve a degraded range resolution for FMCW radar. The proposed post-processing method can achieve an improved range resolution without increasing a signal bandwidth by eliminating factors that can degrade the range resolution based on the non-negative least-squares method. For an FMCW radar adopting the postprocessing method with the center frequency of 76.5 GHz and the signal bandwidth of 200 MHz, simulation results show that the degraded range resolution of 160 cm is improved to 70 cm, and measurements show that two corner reflectors with the radar cross section of 10 dBsm located at 70 cm range intervals can be distinguished.

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“…Existing sensors usually use BPF to extract the harmonic signal. However, the filter design has a direct effect on the suppression of jamming [ 22 , 23 , 24 ]. For instance, when more harmonic signals are used, the BPF-based harmonic acquisition method consumes a larger number of system resources, causing a non-negligible processing delay and performance decrease.…”

Section: Introductionmentioning

confidence: 99%

Anti-Sweep Jamming Design and Implementation Using Multi-Channel Harmonic Timing Sequence Detection for Short-Range FMCW Proximity Sensors

Kong

Yan

et al. 2017

Sensors

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Currently, frequency-modulated continuous-wave (FMCW) proximity sensors are widely used. However, they suffer from a serious sweep jamming problem, which significantly reduces the ranging performance. To improve its anti-jamming capability, this paper analyzed the response mechanism of a proximity sensor with the existence of real target echo signals and sweep jamming, respectively. Then, a multi-channel harmonic timing sequence detection method, using the spectrum components’ distribution difference between the real echo signals and sweep jamming, is proposed. Moreover, a novel fast Fourier transform (FFT)-based implementation was employed to extract multi-channel harmonic information. Compared with the traditional band-pass filter (BPF) implementation, this novel realization scheme only computes FFT once, in each transmission cycle, which significantly reduced hardware resource consumption and improved the real-time performance of the proximity sensors. The proposed method was implemented and proved to be feasible through the numerical simulations and prototype experiments. The results showed that the proximity sensor utilizing the proposed method had better anti-sweep jamming capability and ranging performance.

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Impact of Frequency Ramp Nonlinearity, Phase Noise, and SNR on FMCW Radar Accuracy

Cited by 105 publications

References 15 publications

The Role of Millimeter-Waves in the Distance Measurement Accuracy of an FMCW Radar Sensor

The Role of Millimeter-Waves in the Distance Measurement Accuracy of an FMCW Radar Sensor

Method to improve degraded range resolution due to non-ideal factors in FMCW radar

Anti-Sweep Jamming Design and Implementation Using Multi-Channel Harmonic Timing Sequence Detection for Short-Range FMCW Proximity Sensors

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