Maximum Detection Range Research Articles

Single-shot ranging and velocimetry with a CW lidar far beyond the coherence length of the CW laser

The spectral linewidth of the continuous-wave (CW) lasers is one of the key limitations on the coherent lidar systems, which defines the maximum detection range. Furthermore, precise phase or frequency sweeping requirements are a deterrent in many applications. Here, we present the Phase-Based Multi-Tone Continuous Wave (PB-MTCW) lidar measurement technique that eliminates the necessity of using high coherence laser sources as well as any form of phase or frequency sweeping while employing coherent detection. In particular, we modulate a CW laser source with multiple radio-frequency (RF) tones to generate optical sidebands. Then, we utilize the relative phase variations between the sidebands that are free from laser phase noise to calculate the target distance via post-processing and triangulation algorithms. We prove that the PB-MTCW technique is capable of performing single-shot ranging and velocimetry measurements at more than 500× the coherence length of a CW laser in a benchtop experimental demonstration. Overall, precise phase or frequency sweeping requirements and the spectral linewidth of CW lasers, which defines the maximum detection range, are the key limitations of long-distance coherent lidar systems. The proposed approach overcomes these limitations and enables single-shot ranging and velocimetry measurements, especially for long-range applications such as spacecraft and airborne coherent lidars.

Evaluation of the Coastal Acoustic Buoy for offshore wind for real time mitigation of North Atlantic right whales

A recent Incidental Harassment Authorization requires a 10 km zone to be monitored with passive acoustics before and during pile driving. SMRU Consulting has built the Coastal Acoustic Buoy for Offshore Wind (CABOW) to address this need. Each CABOW consists of: a bottom lander with three hydrophones; data acquisition system; and onboard computer running PAMGuard. The CABOW detects potential calls and relays clips to a base station for classification, bearing estimation, and validation. Bench testing characterized detector performance and measured bearing accuracy as a function of SNR. Field trials used playbacks of real and simulated right whale upcalls to evaluate the detection probability with respect to the range and signal excess of the call; estimate bearing accuracy; and test the range and stability of the radio communications. Field trials indicated a maximum detection range of 4–12 km under high and very low noise levels, respectively. Finally, we used a simulation to compare true and false alarm rates of the CABOW to an equivalent single sensor system for monitoring a fixed area. Simulations show that incorporating bearings to calling animals could provide a substantial improvement in false alarm rates relative to single sensors if properly placed with respect to potential noise sources.

A Monte Carlo approach to modelling detection ranges for killer whales in inshore waters of British Columbia, Canada

Passive underwater listening stations are often used to monitor the presence, distribution and movements of marine mammals. This requires an understanding of the distances at which marine mammal sounds can be detected at a location and at different times given varying ambient noise conditions. Here, we describe a Monte Carlo approach for determining call detection probabilities as a function of distance for networked underwater listening stations deployed by Fisheries and Oceans Canada in the Salish Sea to track endangered Southern Resident Killer Whales. We used ambient sound levels measured in situ, modelled propagation losses determined by two acoustic models, and applied Monte Carlo simulations to capture the variability in call source level and animal depth. Given that only some parts of the call frequency spectrum may be responsible for the maximum detection range, the analysis was carried out independently for consecutive 300 Hz frequency bands. Median detection range estimates ranged from 700 m at the noisiest time and location to 8 km at the quietest. A sensitivity analysis revealed that the frequency distribution of source levels used for the analysis was a major factor affecting detection range results, while differences in propagation losses between summer and winter were less important.

Real-Time System Design for Sensing, Recording and Analyzing Elephant Seismic Waves Through Ground Vibration Algorithm

In this paper, a real-time low-cost geophone-based Elephant Footstep Vibration Detection and Identification (EFVDI) system is proposed. The system design started with a real-time low-cost generalized Footstep Vibration Recording and Analyzing (FVRA) system. A series of field experiments to record elephant footstep vibration (target) signals and other possible interfering ground vibration (noise) sources are conducted using the FVRA system. System’s actual field performance was evaluated in terms of maximum detection range, signal amplitude, detection ratio, signal frequency, signal time span, etc. Variations of system’s performance with several input parameters are also investigated. The recorded signals from target as well as noise sources are analyzed to extract different Signal Parameters (SPs). All SPs are saved in a Ground Vibration Signal Pattern Library (GVSPL) which is then used to frame accurate indigenous Elephant Identification Algorithm (EIA). The EIA is embedded in FVRA system to reshape it as specific Elephant Footstep Vibration Detection and Identification (EFVDI) system. The EFVDI system has successfully segregated elephant footsteps from other noise vibrations with high accuracy under simulated field experiment. The results from the proposed system will provide important data to the ongoing research of developing the much needed highly accurate Elephant Early Warning System (EEWS) in future.

캔테나를 이용한 아두이노기반 FMCW 레이다 시스템 설계

In this study, the design of a low-cost frequency-modulated continuous wave (FMCW) radar system at C-band using commercial off-the-shelf (COTS) components is presented. The proposed radar system consists of low-cost surface-mounting devices and monolithic ICs on a multi-layer FR4 PCB for system integrity. The Tx/Rx antennas (Cantennas) were fabricated with commercial cans based on waveguide dominant mode analysis. The proposed radar system is connected to the Arduino UNO platform, which transfers the received analog backscattered RF signal to MATLAB to display a range versus time intensity (RTI) plot. The designed radar has a maximum detection range of 56.3 m.

대기 굴절률 변화에 따른 레이다 성능 변화에 관한 연구

Factors that contribute to varying radar performance include internal causes such as equipment obsolescence, and external causes such as terrain and atmosphere. In particular, the atmosphere, which is a natural element, causes inevitable performance changes. The refractive index changes with atmospheric conditions in real time and affects the propagation environment, which affects the radar performance. Depending on the refractive index, atmospheric conditions are divided into super, sub, standard, normal, and trap, and the radar performance changes, such as the maximum detection range, occur differently during each atmospheric state. Therefore, it is important to predict and respond to changes in radar performance depending on the atmospheric conditions. In this study, the changes in the maximum detection range at low altitudes and detection performance at a long distance are analyzed using the M&S tool with respect to the refractive index. As a result, the maximum detection range decreases for a larger refractive index and vice versa, while the detection performance at a long distance changes because of abnormal atmospheric conditions.

A CMOS Optoelectronic Receiver IC with an On-Chip Avalanche Photodiode for Home-Monitoring LiDAR Sensors.

This paper presents an optoelectronic receiver (Rx) IC with an on-chip avalanche photodiode (APD) realized in a 0.18-μm CMOS process for the applications of home-monitoring light detection and ranging (LiDAR) sensors, where the on-chip CMOS P+/N-well APD was implemented to avoid the unwanted signal distortion from bondwires and electro-static discharge (ESD) protection diodes. Various circuit techniques are exploited in this work, such as the feedforward transimpedance amplifier for high gain, and a limiting amplifier with negative impedance compensation for wide bandwidth. Measured results demonstrate 93.4-dBΩ transimpedance gain, 790-MHz bandwidth, 12-pA/√Hz noise current spectral density, 6.74-μApp minimum detectable signal that corresponds to the maximum detection range of 10 m, and 56.5-mW power dissipation from a 1.8-V supply. This optoelectronic Rx IC provides a potential for a low-cost low-power solution in the applications of home-monitoring LiDAR sensors.

비접촉식 220V @ 60Hz AC 전원 검출기

We have designed and fabricated a 220V @ 60Hz AC non contact detection for AC power line detector using 180nm megna BCDMOS technology. AC line detector is composed of a 60Hz band pass filter, fixed gain amplifier, comparator and current generator. The 220V AC power line detector with non-contact is designed and fabricated by BCDMOS process. As of the measurement results, maximum detection range of the AC power line detector and differential gain are 30 cm and 20 dB, respectively. The total power consumption is 3mA at 3.3 V coin battery.

High-Resolution and Large-Detection-Range Virtual Antenna Array for Automotive Radar Applications.

Collision avoidance and autonomous control of vehicles have become essential needs for providing a high-quality and safe life. This paper introduces a new generic scheme for a virtual antenna array (VAA) and its application in a train collision-avoidance system (TCAS). The proposed TCAS shall have the capability of identifying the range and angle of an object in front of a moving train and provide the required alerts. Thereby, a new virtual array distribution for both the transmitting and the receiving antenna arrays is introduced to get a long-range object detection and high-resolution multi-input multi-output (MIMO) system. This can be accomplished because the VAA radiation pattern is the multiplication of the radiation patterns for both the transmitting and receiving antenna arrays, which is different than each one of them alone. In this work, the VAA is utilized in radar systems in which the radar range depends on the multiplication of the gain of the transmitting and receiving antennas. So, we introduce a new scheme for the general design of VAA-based radars. A prototype for the antenna system was fixed on a of Texas Instruments platform for the cascading radar. One of the main problems of the VAA is the loss of radiated power in undesired directions, which affects the maximum detection range in beamforming systems and degrades the diversity gain in MIMO applications. These issues have been solved by the introduction of the practical implementation of a proposed high-gain, low side lobe level VAA system for automotive radar that is based on the integration of four AWR1243 RF chips operating in a frequency range of 76 GHz to 81 GHz. It was implemented using low-power 45 nm (TI) RFCMOS technology. The measured gain of the realized VAA was 47.2 dBi, which was 1.815 times higher than that of the Texas instrumentation linear frequency modulated continuous wave (TI’ LFMCW) radar, which was 26 dBi. The proposed VAA saved 45% of the required implementation area compared to the TI’ LFMCW antenna array. The VAA system was fabricated and tested in an anechoic chamber, and it was found that the simulated and measured patterns of the proposed VAA were highly matched in terms of half-power beamwidth and side lobe level.

A 32 × 32-Pixel Flash LiDAR Sensor With Noise Filtering for High-Background Noise Applications

This article introduces a pulsed laser direct time-of-flight (dTOF) flash light detection and ranging (LiDAR) sensor fabricated in 0.18-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> HV CMOS technology. The chip includes <inline-formula> <tex-math notation="LaTeX">$32\times 32$ </tex-math></inline-formula> macro pixels and 1024 time-to-digital converters (TDCs). A noise filtering circuit with different threshold (<inline-formula> <tex-math notation="LaTeX">$\text{N}_{\mathrm {th}}$ </tex-math></inline-formula>) configuration is adopted in each macro pixel [formed by four single-photon avalanche diodes (SPADs)], which can suppress strong background light (BG) induced pile-up. To verify the imaging function and effectiveness of the noise filtering circuit, two systems are implemented (System1 for indoor imaging measurement and System2 for outdoor distance measurement). With the help of the noise filtering circuit and a reasonable signal-to-background noise ratio (SBR), the maximum detection range outdoors with reasonable accuracy can be greatly extended (from 12m &#x0040; N_th &#x003D; 1 of System2 to more than 20m &#x0040; N_th &#x003D; 2 of System2 under 70klux of background noise). The counter in the noise filtering circuit can be reused to get intensity information. A robust 13-bit TDC with a reliable reset is introduced. Thanks to a dedicated START/STOP logic and a Schmitt trigger, large TDC quantization errors can be avoided. It achieves a 200ps resolution (LSB) and exhibits an INL_p-p of 3.55LSB and a DNL_p-p of 0.53LSB. The maximum inter-frame rate can reach 270kfps with 16 IOs operating at speed of 500MHz. Combining 9k inter-frames to get one frame, a frame rate of 30 is achieved for an indoor 3-D imaging. For outdoor measurement, more laser pulses should be accumulated.

Refractive index sensing characteristics of electromagnetic metamaterial absorber in terahertz band

&lt;sec&gt;Terahertz metamaterial (THz MM) absorber, as an important type of MM functional device, can not only achieve perfect absorption of incident THz waves, but also act as a refractive index sensor to capture and monitor changes in the information about surrounding environment. Generally, the sensing characteristics of the THz MM absorber can be improved by optimizing the structure of the surface metal resonance unit and changing the material and shape of the dielectric layer. In order to further study the influence of the intermediate dielectric layer on the sensing characteristics of the THz MM absorber, in this paper we implement three THz MM absorbers with continuous dielectric layer, discontinuous dielectric layer and microcavity structure based on the metallic split-ring resonator array, and conduct in-depth study of their sensing characteristics and sensing mechanism. &lt;/sec&gt;&lt;sec&gt;The THz MM absorber with continuous dielectric layer and metallic split-ring resonator array can be used as a refractive index sensor to realize the sensing detection of analytes coated on its surface with different refractive indexes. However, it can be seen from its corresponding refractive index frequency sensitivity and FOM value that the detection sensitivity of this sensor is limited, and its sensing performance still needs improving. The main reason is that most of the resonant electromagnetic (EM) field of the THz MM absorber is tightly bound in the intermediate dielectric layer, and only the fringe field extending to the surface of the MM absorber resonant unit array can interact with the analyte to be measured, and the intensity of this part of the field directly determines the sensitivity of the sensor. In order to further improve the refractive index frequency sensitivity of the THz MM absorber, reduce the restriction of the intermediate dielectric layer to the resonant EM field, and enhance the interaction between the resonant EM field and the analyte to be measured, a THz MM absorber with discontinuous dielectric layer is proposed and studied. Compared with the THz MM absorber with continuous dielectric layer, the THz MM absorber based on discontinuous dielectric layer can be used as a refractive index sensor to realize higher-sensitivity sensing and detection of the analyte coated on the surface. In order to further enhance the interaction between the resonant EM field and the analyte to be measured, and improve the refractive index frequency sensitivity of the THz MM absorber, a THz MM absorber with a microcavity structure is proposed. For this THz MM absorber, the analyte to be measured filled in the microcavity structure can serve as the intermediate dielectric layer of the THz MM absorber, and when the metallic split-ring resonator array is completely immersed in the analyte to be measured, the resonant EM field originally confined in the intermediate dielectric layer and the analyte to be measured completely overlap in space. Therefore, compared with the first two THz MM absorbers, THz MM absorber with a microcavity structure achieves the tightly and fully contacting the resonant EM field, thereby greatly improving its sensitivity as a sensor. &lt;/sec&gt;&lt;sec&gt;The results show that in order to improve the sensing characteristics of the THz MM absorber, such as the refractive index sensitivity and the maximum detection range, in addition to using the materials with lower relatively permittivity as the intermediate dielectric layer, the morphology of the intermediate dielectric layer can be changed, thereby reducing the restraint of the intermediate dielectric layer on the resonant field and enhancing the coupling between the resonant field and the analyte to be measured. Compared with the conventional THz MM absorber with continuous dielectric layer, the MM absorber with discontinuous dielectric layer and microcavity structure have many superior sensing characteristics, and can be applied to the high-sensitivity and rapid detection of analytes to be measured, and has a broader application prospect in the future sensing field. &lt;/sec&gt;

A Modified Radon Fourier Transform for GNSS-Based Bistatic Radar Target Detection

The Global Navigation Satellite System (GNSS)-based passive bistatic radar (PBR) which uses the GNSS signal as the illuminators of opportunity is studied for moving target detection (MTD). GNSS-based PBR has many advantages due to the removal of the transmitting device; however, its fundamental limitation is the low power density of the GNSS signal. Therefore, the integration time should be sufficiently long to obtain a promising maximum detectable range. On the other hand, the integration time is limited by the range migration and Doppler migration of the echo caused by target motion. In this letter, a novel MTD algorithm is proposed for the GNSS-based PBR, by employing a modified radon Fourier transform (MRFT) to achieve the required long-time integration for moving targets. The MRFT integrates the echo energy via joint searching of range, Doppler, and Doppler rate of the target, which can handle not only the range migration but also the Doppler migration problems, and significantly improves the signal-to-noise ratio (SNR) of the echo signal. An experiment using the GPS L5 signal as the illumination source is conducted and a moving car is successfully detected by the proposed algorithm, although significant range migration and Doppler migration are present due to variation of its speed.

Multi-radiators on active scattering characteristics for metal sphere model

In order to investigate the influence of multi-radiators, active scattering characteristics, which can be reflected by the active radar cross section (ARCS), are investigated by incorporating the multi-radiators with the radar-radiator. The proposed implementation takes advantage of the ARCS concept in terms of considerable accuracy and close to reality especially in the complex electromagnetic environment. The metal sphere model is analyzed to demonstrate the effectiveness of the proposed implementation. Several procedures are employed during the investigation. The ARCS of the metal sphere model is compared with its radar cross section with a single radar-radiator. The frequency characteristic of the ARCS for a metal sphere model with multi-radiators is calculated. The changes in the ARCS with different phases, field intensities, field polarization directions are given. An example is given to illustrate the change in the maximum detection range caused by multi-radiators. Through the results, it can be concluded that the active scattering characteristics of the metal sphere model can be significantly influenced by the multi-radiators.

Clicking throughout the year: sperm whale clicks in relation to environmental conditions off the west coast of South Africa

Knowledge of cetacean occurrence and behaviour in southern African waters is limited, and passive acoustic monitoring has the potential to address this gap efficiently. Seasonal acoustic occurrence and diel-vocalizing patterns of sperm whales in relation to environmental conditions are described here using passive acoustic monitoring data collected off the west coast of South Africa. Four autonomous acoustic recorders (AARs) were deployed on 3 oceanographic moorings from July 2014 to January 2017. Sperm whale clicks were detected year round in most recording sites, with peaks in acoustic occurrence in summer and late winter through spring. Diel-vocalizing patterns were detected in winter, spring and summer. Higher percentages of sperm whale clicks were recorded by AARs deployed at 1100 m water depth compared to those concurrently deployed at 850 and 4500 m, likely inferring that the whales exhibited some preference to water depths around 1100 m. Acoustic propagation modelling suggested a maximum detection range of 83 km in winter for sperm whale clicks produced at 1100 m. Random forest models classified daylight regime, sea surface height anomaly and month of the year as the most important predictors of sperm whale acoustic occurrence. The continuous acoustic occurrence of sperm whales suggests that the study area supports large biomasses of prey to sustain this species’ food requirements year round. This is the first study to describe the seasonal acoustic occurrence and diel-vocalizing patterns of sperm whales off the west coast of South Africa, extending knowledge of the species previously available only through whaling records.

Revisiting the bioelectrochemical system based biosensor for organic sensing and the prospect on constructed wetland-microbial fuel cell

Bioelectrochemical system (BES) based biosensors for organic sensing has long been investigated. However, there is no uniform criterion to evaluate directly the performance of the BES based biosensors due to their different scale. Here, for the first time, we show that the normalized maximum detection range (NMDR) and normalized sensing time (NST) can potentially be used as the two criteria in BES based biosensors for organic sensing. Thereafter, the recently emerged, relatively larger scale BES (i.e. constructed wetland-microbial fuel cell, CW-MFC) was specifically examined in this study. The biocathode formation and the influence of anodic material on sensor performance were systematically evaluated. The system with metal-based anode was found to produce a more stable and quicker response (low NST) than that with carbon-based anode. Significantly, the continuous loading mode was found to greatly reduce the NMDR compared to the batch mode, and the hydraulic residence time (HRT) is the critical factor determining the NMDR. Furthermore, it was found that the electrical signals generated from the CW-MFC system were insignificantly influenced by some specific chemical disturbances, such as Cu2+ and herbicide. Therefore, normalized toxicity (NT) is suggested to be considered in BES based biosensor. However, for chemicals with higher reduction potentials (NO3− in this work), the system presented a high response, enabling its potential for monitoring NO3− in effluents or groundwater. This study can hopefully contribute to further development of the sustainable BES based biosensors in CW.

Potassium tantalate niobate (KTN) crystal-based polarization-modulated 3D ladar with a large field of view.

An innovative 3D ladar that utilizes potassium tantalate niobate (KTN) crystal as a polarization modulator is proposed in this Letter. The optical isotropy of KTN in cubic phase can effectively suppress the range errors induced by the incident angles of collected beams in 3D imaging. The giant quadratic electro-optic coefficient can dramatically lower the voltage that is required to modulate the polarization so that a high voltage amplifier with less noise can be used to improve the ranging performances. By virtue of these two advantages, a range error of 4.8 cm and a range precision of 4.4 cm at 15 m have been achieved under a large field of view of 20° (about 0.35 rad) and a maximum detection range without ambiguity of 60 m.

Detection probability and density estimation of fin whales by a seaglider

The effectiveness of gliders is evaluated for passive acoustic density estimation of fin whales. An estimate of the probability of detection as a function of range (or, equivalently, effective survey area) is required to estimate density from acoustic data collected by a single-hydrophone glider platform. A cabled hydrophone array was used to estimate fin whale localizations and tracks concurrently with a glider survey. Fin whale tracks were used as detection trials and a detection function for snapshots containing fin whale 20 Hz pulses recorded by the glider was modeled using a generalized additive model. Detection probability was strongly dependent on 40 Hz noise levels recorded on the glider. At the median noise level of 97 dB re 1μPa2/Hz, detection probability was near one at zero horizontal distance, and maximum detection range was near 40 km. The estimated effective survey area at this noise level was 870 km2. Using estimates of vocal rates and group size from tagged and tracked fin whales, respectively, the density was estimated as 2.4 fin whales per 1000 km2 (coefficient of variation 0.55). The framework presented here could be applied to other baleen whale species to advance the use of gliders for density estimation of cetaceans.

Quantifying the performance of ray-based Blind Deconvolution (RBD) algorithm for long-range shipping sources

The ray-based Blind Deconvolution (RBD) can provide an estimate of the relative arrival-times of the channel impulse responses (CIRs) between a shipping source (acting as a shallow source of opportunity) and a remote receiver array (e.g., a short bottom-mounted vertical line array (VLA)) [Durofchalk and Sabra, JASA 147(3), 1927–1938 (2020)]. Previous RBD studies primarily rely on beamforming on the (most energetic) direct path to estimate the phase of the unknown source; but in typical downward refracting environments the direct path is only observable at short ranges for a (very shallow) shipping source. Alternatively, the overall performance of the RBD algorithm when treating long range sources of opportunity remains to be evaluated in similar settings when only bottom-interacting multipath arrivals can reach the VLA, i.e., beyond the range when the direct path is observable. In this study, a combination of numerical simulations and experimental validation (using the SBCEx16 experiment conducted in the Santa Barbara shipping channel with short, bottom-mounted VLAs) is used to investigate the maximum detection range of shipping sources of opportunity via multipath arrivals as a function of frequency, bathymetry effects and anisotropy of the shipping source and the implications for estimating the CIRs using the RBD method.

Analytical volume model for optimized spatial radar bat detection in onshore wind parks.

To develop mitigation measures for the protection of bats in close proximity to onshore wind turbines, new detection techniques covering large-scale environments and techniques, which are able to track individuals are required. Radar based observations, successfully applied in ornithological studies, offer a promising potential, but come with challenges regarding the comparability of measurements and noise interference (ground clutter) from objects within detection range. This paper presents improvements of a commercially available inexpensive pulse radar for 3D spatial detection of bat-sized objects in onshore wind parks. A new analytical spatial detection volume model is presented incorporating calibrated radar data and landscape parameters such as clutter. Computer simulation programs to process the analytical spatial detection volume model were developed. For model calibration, the minimum signal power of the radar was experimentally determined with the radar cross section (RCS) of an artificial bat (similar to Nyctalus noctula), resulting in a maximum detection range of 800 m and a corresponding RCS of 12.7 cm². Additionally, the spatial volume for radar detection was optimized with a clutter shielding fence (CSF). Adjusting the volume model by incorporating a theoretical model of the CSF, an extension of the detection volume by a factor of 2.5 was achieved, while the total volume of a 105° horizontal angular radar image section yields 0.0105 km³. Extrapolation and comparison with state-of-the-art acoustic bat detection result in a 270 times larger volume, confirming the large-scale detection capabilities of the pulse radar.

МЕТОДИКА ОПРЕДЕЛЕНИЯ ПОЛЯ ОБНАРУЖЕНИЯ БЕСПИЛОТНЫХ ЛЕТАТЕЛЬНЫХ АППАРАТОВ НАЗЕМНЫМ НАБЛЮДАТЕЛЕМ

The widespread use of small-sized unmanned aerial vehicles (UAVs) makes it urgent to control their use in the airspace over strategic infrastructure facilities. The design features of UAVs provide them with low visibility in all existing observation ranges: radar, visual, thermal, and acoustic. In this regard, for the reliable detection of such aircraft, it is necessary to use complex systems that conduct simultaneous observations in all available ranges. To optimize the location of such systems, the problem arises of determining the fields of reliable detection of UAVs for each of the means included in the system. To solve this problem for the means of visual and thermal detection based on the previously developed technique for determining the indications of the detection range based on the determination of the visually visible area of the UAV, calculated from the existing three-dimensional model of the vehicle, a new method is proposed for analyzing the characteristics of the UAV visibility for the ground observer. The application of the proposed technique is demonstrated by the example of two UAV models: ECO – with an internal combustion engine, and ELECTRA – with an electric motor. The concept of the indicatrix of the detection field is introduced, as an indicatrix of the maximum detection range, transferred from the UAV coordinate system to the observer's coordinate system by simple geometric transformations. Based on the indications of the detection field, it is possible to carry out both a direct comparative analysis of the visual visibility of UAVs and to obtain additional information from them, useful for making recommendations on the parameters of the UAV flight, in particular, the flight altitude and the direction of approach to the location of a potential observer. If there is an indicatrix of the detection field for the analyzed UAV, the calculation of the detection zone boundary can be performed automatically for any given height. This allows you to visualize information about the limits within which the UAV detection range can change depending on the direction and altitude of its flight.