Data-Based Quadrature Imbalance Compensation for a CW Doppler Radar System

Singh, Aditya; Gao, Xiaomeng; Yavari, Ehsan; Zakrzewski, Mari; Cao, Xi; Lubecke, Victor M.; Borić–Lubecke, Olga

doi:10.1109/tmtt.2013.2249525

Cited by 94 publications

(50 citation statements)

References 10 publications

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“…Several subsequent optional calibration steps minimize the remaining absolute measurement error, e.g., by applying ellipse fitting algorithms (Singh et al, 2013;Zakrzewski et al, 2014;Linz et al, 2014) or polynomial approximation based error correction (Will et al, 2017a;Vinci et al, 2011;AOlopade and Helaoui, 2014), or by utilizing a look-up table (Vinci et al, 2011). Thus, the importance of repeatability as a figure of merit increases, which is typically analyzed by evaluating the standard deviation at each calibration point.…”

Section: Measurement Resultsmentioning

confidence: 99%

“…An orthogonalization of the elliptical shape had been investigated in preliminary experiments which yield best results by minimizing the I/Q offset. Furthermore, several algorithms for estimating and reconstructing elliptic I/Q representations have already been published (Singh et al, 2013;Zakrzewski et al, 2014;Linz et al, 2014).…”

Section: I/q Offset Cancelationmentioning

confidence: 99%

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A 24 GHz Waveguide based Radar System using an Advanced Algorithm for I/Q Offset Cancelation

et al. 2017

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Abstract. Precise position measurement with micrometer accuracy plays an important role in modern industrial applications. Herewith, a guided wave Six-Port interferometric radar system is presented. Due to limited matching and discontinuities in the radio frequency part of the system, the designers have to deal with DC offsets. The offset voltages in the baseband lead to worse relative modulation dynamics relating to the full scale range of the analog-to-digital converters and thus, considerably degrade the system performance. While common cancelation techniques try to estimate and extinguish the DC offsets directly, the proposed radar system is satisfied with equalizing both DC offsets for each of the two differential baseband signal pairs. Since the complex representation of the baseband signals is utilized for a subsequent arctangent demodulation, the proposed offset equalization implicates a centering of the in-phase and quadrature (I/Q) components of the received signal, which is sufficient to simplify the demodulation and improve the phase accuracy. Therefore, a standard Six-Port radar system is extended and a variable phase shifter plus variable attenuators are inserted at different positions. An intelligent algorithm adjusts these configurable components to achieve optimal I/Q offset cancelation.

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Section: Measurement Resultsmentioning

confidence: 99%

Section: I/q Offset Cancelationmentioning

confidence: 99%

A 24 GHz Waveguide based Radar System using an Advanced Algorithm for I/Q Offset Cancelation

et al. 2017

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show abstract

“…Table 4 shows the SNR values based on Table 5 shows the frequency estimates based on the reconstructed signal from different IMFs. Results indicate VS primarily concentrates upon IMF 6 and IMF 5 . As a result, the VS can be extracted effectively based on the selected IMFs.…”

Section: Performance Of Clutter Suppressionmentioning

confidence: 96%

“…Ultra-wide band (UWB) impulse radar has been widely applied in indoor target localization, VS detection, and human fall detection by employing the continuous wave [5][6][7][8]. As a better alternative, UWB pulse radar has been widely used in moving target detection [3,9,10], through-wall imaging [11,12] and post-earthquake search and rescue [13][14][15] due to its insightful advantages such as strong permeability and excellent time resolution.…”

Section: Introductionmentioning

confidence: 99%

`Through-wall human being detection using UWB impulse radar

Liang

Zhang

et al. 2018

J Wireless Com Network

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Ultra-wideband (UWB) impulse radar plays an important role in contactless vital sign (VS) detection. The VS can be extracted remotely by acquiring the oscillations in the human chest. Unfortunately, it is usually challenging to identify VS due to the low signal-to-noise ratio (SNR) only based on the traditional fast Fourier transform (FFT) especially in complicated conditions. To extract VS accurately, this paper presents a new scheme by analyzing the skewness characteristic of the received UWB impulses, which are modulated by life activities. The distance from the human subject to the radar antenna can be calculated by performing the discrete short-time Fourier transform (DSFT) on skewness. The frequency of human respiratory movement can be estimated based on the developed ensemble empirical mode decomposition (EEMD)-based accumulation technique by canceling out the harmonics effectively. The performance of the developed detection method is tested with several experiments carried out in different environments.

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“…The extent of signal distortion depends on the imbalance between the in-phase (I) and quadrature (Q) channels. This is discussed, for example, in [12] and [13]. With high-quality RF components, the imbalance will be small, thus resulting in a small distortion only.…”

Section: Introductionmentioning

confidence: 99%

Quadrature Imbalance Compensation With Ellipse-Fitting Methods for Microwave Radar Physiological Sensing

Zakrzewski

Singh

Yavari

et al. 2014

IEEE Trans. Microwave Theory Techn.

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Accurate displacement measurement using quadrature Doppler radar requires amplitudes and phase imbalance compensation. Previously, this imbalance calibration has required cumbersome hardware modifications and thus can only be performed in a laboratory setting. Recently, a data-based method that does not require hardware modifications has been proposed. This simplifies the calibration process and allows the calibration to be performed on-site periodically. The method is called ellipse fitting. In this paper, the different factors affecting imbalance estimation accuracy, namely, arc length, initial phase angle, and noise level were thoroughly investigated. The Levenberg-Marquardt (LM) algorithm is proposed for the first time to increase the estimation accuracy as compared to the previously suggested algebraic fitting. Comprehensive simulations and experimental data show that the algebraic fitting method results in biased estimates. The proposed LM method has also been demonstrated to be more robust to noise, varying arc lengths, and different initial angles. The LM method reaches sufficient imbalance estimation accuracy with an arc length of 40% and a noise level of 1.5%.

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Data-Based Quadrature Imbalance Compensation for a CW Doppler Radar System

Cited by 94 publications

References 10 publications

A 24 GHz Waveguide based Radar System using an Advanced Algorithm for I/Q Offset Cancelation

A 24 GHz Waveguide based Radar System using an Advanced Algorithm for I/Q Offset Cancelation

`Through-wall human being detection using UWB impulse radar

Quadrature Imbalance Compensation With Ellipse-Fitting Methods for Microwave Radar Physiological Sensing

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