Two-dimensional signal processing in FMCW radars

IEEE Signal Processing Magazine, 1999

IEEE Sensors Journal, 2020

Classical saw-tooth Frequency Modulated Continuous Wave (FMCW) radars experience a coupling between the maximum unambiguous Doppler-velocity interval, maximum operational range, range-resolution and processing gain. Operationally, a trade-off is often necessarily made between these parameters. In this paper, we propose a waveform and a processing method that decouples the aforementioned parameter dependencies at the price of using multiple receiver channels within the radar. The proposed method exploits the fact that beatfrequency signals have the same baseband frequency, even if the transmitted and received chirps occupy different radio frequency bands, and have different center-frequencies. We concatenate those baseband signals in the time-frequency domain to restore the range-resolution and processing gain. An overview of FMCW parameters trade-off for related waveforms and a feasibility and limitations analysis of implementing the proposed processing method are presented. The method is verified by simulations and experiments with an FMCW radar for stable, moving and extended-moving targets. We additionally have highlighted its non-idealities in the simulations and experiments. We found that the proposed method indeed alleviates the trade-off between FMCW operational parameters and allows the extension of the Doppler ambiguity interval without compromising on those parameters.

IOP Conference Series: Materials Science and Engineering, 2019

Frequency Modulated Continuous Wave (FMCW) radars get target range and Doppler information by extracting the target beat frequency and phase exchange based on the well-known Two-Dimensional Fast Fourier Transform (2D-FFT) processing algorithm. Target whose beat frequency does not lie on the FFT grids suffers from great detection degradation. Doubling the number of FFT points, and consequently, the hardware processing complexity is a common solution to solve this problem. In this paper, a proposed method to increase the detection performance of these targets and avoid increasing system complexity is introduced. The proposed method depends on applying a proposed filter following the first and second FFT algorithms. The filter order and weights are chosen so that only one peak form the adjacent peaks of off-pin targets are distinguished. The superiority of the proposed method over the traditional one is validated for different scenarios through the Receiver Operating Characteristic (ROC).

2017

The word RADAR is Radio Detection and Ranging. Radar system uses electromagnetic waves to search for targets. When target is detected then energy is reflected back to radar which is called as echoes. These echoes are received and processed by receiver to determine the target information. Frequency Modulated Continuous Wave radar (FMCW) which is a special type of radar. FMCW radar is simple, small in size and uses lower transmitting power as compare to other radars. We are using 10 GHz of FMCW radar. In this project we will be doing Modeling and Implementation of 10-GHz FMCW Height Measurement Device in Simulink to find different parameters such as distance between the UAV and ground, beat frequency, SNR, noise figure, output power, bandwidth etc. operating at 10 GHz. And also doing signal processing that to be performed on intermediate frequency (IF) signal (Beat frequency) during range estimation of FMCW radar which is obtained after simulation.

IEEE Sensors Journal, 2019

A reconfigurable range-Doppler processing method for FMCW radar is presented. By concatenating beat-frequency signals from more than one sweep, a continuous beat-frequency signal for the whole coherent processing interval (CPI) can be created. As a result, continuous targets' observation time is extended beyond that of a single chirp duration, leading to range resolution improvement. The created continuous beat-frequency signal can be split in the digital domain to any two-dimensional slow-time and fast-time matrices with the same number of elements as in the original signals, which offers a realization of a software-defined pulse/sweep repetition rate in range-Doppler processing. The signal concatenation is done in the short-time Fourier transform (STFT) domain, where the beat-frequency slices are extrapolated to compensate for the observation time lost in the transient region between sweeps, and then a phase correction is applied to each frequency-slice as appropriate, followed by an inverse STFT (ISTFT). The proposed technique is verified with simulation and experiments with an FMCW radar for stable and moving target scenarios. We found that the method allows for range resolution improvement without the transmission of additional bandwidth and also allows for the ability to observe different resolution granularities in parallel from one CPI. It additionally allows the decoupling of the transmitted PRF from the Doppler processing PRF, permitting the facility to observe different unambiguous Doppler velocity intervals from one CPI, without compromising on the total CPI processing gain.

Hereby I declare that all information in this document has been obtained and presented in accordance with academic rules and ethical conduct. I also declare that, as required by these rules and conduct, I have fully cited and referenced all material and results that are not original to this work. Name, Last Name : Yaşar Barış Yetkil Signature : iv ABSTRACT DESIGN OF AN FM-CW RADAR ALTIMETER pages Frequency modulated continuous wave (FM-CW) radar altimeters are used in civil and military applications. Proximity fuses, automatic cruise control systems of cars, radar altimeter of planes are examples to these applications. The goal of this thesis is to present a method for altitude determination using an FM-CW radar. For this purpose principles of radars and FM-CW systems are studied and related subjects are inspected. After this inspection, algorithms for altitude determination are evaluated. Consequently signal detection and processing methods are proposed to build an altitude determining algorithm. Also an analytical test environment for altitudes between 100 m and 4000 m is developed in computer as a result of researches. Test environment simulated the performance of altitude determining algorithm and FM-CW Radar Altimeter. The hardware is designed and implemented accordingly.

Journal of Telecommunication, Electronic and Computer Engineering, 2018

A Frequency Modulated Continuous Wave (FMCW) Doppler radar was assembled to detect human as sample target. Its operating frequency is at 2.4GHz with transmitting power of 10.41 dBm. Range resolution of the radar is 2.8 meters at 53.2MHz signal bandwidth and chirp waveform of 40ms. The radar exploits Doppler principle to acquire the range and velocity information of targets whilst a Moving Target Indicator (MTI) pulse canceller is utilized to filter incoming noise signal. With the use of Chirp period-bandwidth product Frequency Modulated (FM) waveform and deramping process, the radars’ Signal to Noise Ratio (SNR) was improved up to 42 dB. The attained maximum range is about 200 meters for a target with Radar Cross Section (RCS) of 1m2. The constructed radar is capable to measure the speed of moving target at 0.645m/s and above with great accuracy. The radar can detect and determine the position of pedestrians with 0.18% percentage error.

For civil and military purposes FMCW radars are widely used. The theoretical background is wellestablished. Nevertheless, improvement of various aspects of these radars is still required. Signal processing is one of the crucial points of the system which determines the capabilities of the radar. In this study a zero crossing detector implementation, which can be efficiently used for target detection and range calculation in short range FMCW range detector is proposed. The duration between consecutive zero-crossings are used as the data instead of the number of cycles per unit time. Experimental evaluation of its performance is also given.

2012

Spatial localization of moving targets using a Monopulse/FMCW Radar system signal processing scheme is presented in this work. During many years radar sensor application has been used to measure different target parameters and consecutively leading to spatial localization systems, so that has been an active research area in many important fields, from military to civilian applications. Spatial localization of moving targets consists of sensing and estimating the coordinates where the target is located and its speed and direction.

2001

The paper presents a simple method for estimating nonlinear frequency distortions of linear frequency modulated (LFM) signals used in FMCW radars. This method, derived from the polynomial model of the nonlinear FM signal phase, is based on finding the maximum of two-dimensional chirp-like transform of the IF video signal. The IF signal is obtained by mixing transmitted FM signal with its delayed copy. Using suggested transform we show that the presented method is able to detect and classify signal distortions.