A study of some FMCW radar algorithms for target location at low frequencies

Abstract

FMCW (frequency‐modulated continuous wave) radar is a simple and inexpensive technique for target location. The resolution is given by the available bandwidth and the directivity of the antenna. Resolution is not a problem at high frequencies, while at low frequencies (the HF and VHF band), and especially for mobile platforms, the required size of the antenna becomes impractical. In order to obtain the bearing of the targets, without relying on directivity, one may use a simple two‐dimensional trilateration method that involves several platforms. Since this approach covers an area, rather than a sector, the range is reduced to some tens of kilometers. The VHF band and a bandwidth below 10 MHz is a good choice if the priority is to reduce radio interference. Fast targets, corresponding to a significant Doppler shift, have not been considered. The problem of ghost targets has been studied for both monostatic and multistatic radar. When there is a confluence of echoes, more bandwidth is required to maintain the accuracy of a few meters that is normally obtained in the simulation.

Why the brown ghost chirps at night

“…Here, we emphasize the role of chirps as homeoactive signals - as opposed to alloactive - to underline the fact that chirps represent active modulations of signal frequency possibly aimed at optimizing the otherwise passive beat detection occurring constantly and unintentionally (Zweifel and Hartmann, 2020). To our knowledge, this would be a unique biological example of how underwater object localization can be enhanced instantaneously by sinewave FM probes without the assessment of echo-delays (a similar strategy is currently used in continuous-wave frequency-modulated - CWFM - radars to maximize signal-to-noise ratio and improve object distance estimates; Gurgel and Schlick, 2007, Sandström and Akeab, 2016). By providing a novel and more parsimonious explanation to explain chirping behavior, this study revives the debate on the reasons why these nocturnal bony fish evolved this signaling system.…”

Design of Digital Architecture for real-time T-F Imaging with new Radar Waveform

“…The working of DDS is particularly versatile because it functions as a digital signal processing device, making it straightforward to introduce modulation capabilities. The DDS reliably produces the desired output frequency [13][14][15].…”

Deep Learning-Based Indoor Distance Estimation Scheme Using FMCW Radar

“…By calculating the beat frequency caused by the time delay, the distance can be calculated by means of a formula with the signal cycle and frequency range, as shown in Equations (3) and (4), where is the beat frequency, B is the bandwidth of modulating frequency, R is the distance, T is the period of the signal emitted, and c is the speed of light. The calculation formula is expressed as follows [11,[15][16][17][18][19][20]:…”