As we witness the rise of automated driving, the driver's role is transforming, turning the car into a space for leisure, productivity, and connectivity. The shift from driver to passenger prompts a reimagining of interior concepts.&nbsp;Smart In-Cabin Monitoring Systems (ICMS) are required to enable this transformation, offering intuitive interaction, comfort, and new services while always ensuring and even increasing the safety of all occupants.&nbsp;<h1 dir="ltr">In-Cabin Monitoring Systems</h1>In-Cabin Monitoring Systems monitor and analyse the activities and behaviours of occupants within a vehicle's cabin. Their primary goal is to enhance safety, security, and convenience. Easy said, but a quite challenging and complex task that requires the implementation of multiple use-cases with different requirements.&nbsp;To enable the highest level of safety, the ICMS checks vital signs and detects driver drowsiness as well as readiness to take back from an autonomous driving mode, like a highway pilot. It monitors who is in the car, aiding in seat belt reminders, optimizing airbag deployment, and preventing children from being left behind. Security is increased by proximity and intrusion detection inside and near the car or by spoofing robust face-authentication to enable secure connectivity to private data and personalized services. Finally, to add convenience and to turn the car into a space for leisure, the ICMS has to make real-time body and finger tracking for intuitive interaction, gesture-controlled rear seat entertainment, and a personalized user experience.&nbsp;To fulfill such versatile tasks, the In-Cabin Monitoring System utilizes a combination of sensors, cameras, and artificial intelligence (AI) algorithms. This article focuses on two pivotal technologies that combine to enable cutting-edge ICMSs: radar sensors and Time-of-Flight (ToF) cameras.<h1 dir="ltr">Radar sensors</h1>Radar (Radio Detection and Ranging) sensors emit radio waves and measure the time it takes for the waves to bounce off objects and return. This information is used to determine the object's distance, speed, and even direction. When integrated into the cabin environment, radar sensors enable a range of unobstructed in-cabin sensing (1). The ability to measure through most materials and the sensors’ small package size means they are able to be designed seamlessly into the car's design. Furthermore, the low power consumption even allows for operating a radar system in a parked car.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNzA2NzkyNjE4MjgzLUlNQUdFUy0wMSAoMSkuanBnIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 300px;" class="fr-fic fr-dib">The radar working principle.<h1 dir="ltr" id="isPasted">Time of Flight (ToF) Cameras</h1>Time-of-Flight (ToF) cameras transmit modulated infrared light onto the scene of interest. The ToF imager captures the reflected light and measures amplitude and phase difference per pixel. The result is a 3D image of the entire scene consisting of the exact distance per pixel plus a gray-scale image. It operates in all lighting conditions: in darkness, strong sunlight or fast-changing lighting conditions. ToF provides the most robust and feature-rich data for vision-based algorithms and the generation of detailed 3D body models of passengers and objects.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNzA2NzkyNjUzNzMyLUlNQUdFUy0wMiAoMSkuanBnIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 300px;" class="fr-fic fr-dib">Time-of-Flight working principle.<h1 dir="ltr" id="isPasted">In-Cabin Sensing Use Cases</h1>Radar and Time-of-Flight are, by principle, two completely different technologies. As described, radar sensors utilize radio waves, having the benefit of overcoming occlusions of the car seats, having ultra-low power consumption, and the ability to detect tiny movements like the chest movements of a breathing baby. On the other hand, you do not get any image data of your surroundings in order to detect facial expressions or gaze direction or to do detailed object classification. Meanwhile, ToF cameras provide such details together with the exact distance information while being limited to the field-of-view of the camera lens, the pixel resolution, and occlusions. Both technologies have unique merits and limitations, making them suitable for distinct applications. When having a closer look, they are complementary, and the combination of radar and ToF results in a more robust ICMS that gathers data from two distinct sources to cover all major in-cabin use cases.&nbsp;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNzA2NzkxOTYyMzA2LTE3MDY3OTE5NjIzMDYucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 300px;" class="fr-fic fr-dib">As discussed above, radar sensors and ToF can be combined to create ICMSs that have a broad range of features, utilizing the strengths of each technology resulting in more effective and meticulous monitoring. Below we look at some of the features of a cutting edge ICMS and highlight how each case scenario is delivered using radar and/or ToF sensors.<h3 dir="ltr">Child Presence Detection (CPD)</h3>A particularly advantageous feature of an ICMS is the ability to monitor the occupancy of the car’s interior. Occupancy detection is especially useful to sense the presence of unattended children or pets in a vehicle. According to the US Department of Transportation, an average of 38 children under the age of 15 die each year from heat stroke after being left in a vehicle (2). To address the issue, the US Congress issued the Hot Car Act 2021 (3) and the Euro NCAP announced additional award points to vehicle manufacturers who implement the child presence detection (CPD) feature (4).&nbsp;A radar sensor is able to scan the area within the vehicle, including seats and footwell areas, and prompt the ICMS to send out a warning if any vital signs are detected while the car is parked and the temperature has reached a certain level. The operation of radars is unobstructed by seating and other non-metal materials, making them able to detect children and pets in back seats, infants placed in rear-facing seats, and even children covered by objects such as blankets.&nbsp;<h3 dir="ltr">Seat Occupancy Detection and Smart Airbags</h3>Seat Occupancy Detection (SOD) localizes the number of vehicle occupants and their specific&nbsp;<iframe id="641421a7785b8e00080e09d6" width="250" class="specs-iframe" height="440" src="https://wevolver.com/iframe/specs/infineon-bgt60ltr11aip-autonomous-radar-sensor?iframe=true" frameborder="0" scrolling="no" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true"></iframe> locations to optimize seatbelt reminder (SBR) systems and airbag deployment systems. The radar senses when a seat is unoccupied, and then the ICMS communicates to the vehicle’s airbag control module, preventing the airbag from deploying in case of an accident.&nbsp;While radar sensors detect occupancy, ToF cameras allow an ICMS to create 3D body models of the driver and passengers. This information can be used to make accurate passenger size and weight estimates and provides the exact positioning of occupants towards the airbag, which can effectively aid in optimized airbag deployment. In particular during autonomous driving modes, when drivers will be allowed to change their seat position, the ICMS can provide the necessary data to adapt airbags and restraints for maximum safety.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNzA2NzkzMTY4NTk5LUZyb250IHZpZXcgLSBUb0YgZGF0YSBvdmVybGF5IG9mIGRlb3B0aCBhbmQgYW1wbGl0dWRlLnBuZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 300px;" class="fr-fic fr-dib">Infineon’s Time of Flight (ToF) sensors showing a depth map of in-cabin environment.Another potential application of SOD lies in seatbelt alerts. In this case, radar can be used to check whether a seat is occupied and coordinate with the seat belt detection systems of the car to check if the passenger is buckled in or not. With the complementary ToF data, the ICMS could even see if the seatbelts are fastened correctly.As described, having both data from radar and ToF sensors available increases the robustness of the use cases, and the kind of redundant data also supports meeting functional safety requirements for airbag applications.<h3 dir="ltr">Intrusion Alert</h3>Radar sensing allows an ICMS to detect when an intruder tries to gain access to a vehicle. This is done by programming the ICMS to detect when an object such as a hand or weapon is inserted into the car through a window, sunroof, or the trunk, and in turn sound an audible alarm or notify the driver on a smart device. This allows the monitoring system to protect the car from theft and secure the interior contents using intrusion alert systems.<h3 dir="ltr">Proximity Alert</h3>The internal environment of a vehicle is not the only area that can be monitored using radar sensing. Radars can also be used for constantly monitoring the close proximity of a vehicle and detect if another vehicle is too close or if a person is attempting to damage or break in. Based on this information, an alarm system can be triggered to flash the headlights or honk the horn to ward off potential intruders. Additionally, a notification can also be sent to the driver if they are not near the vehicle.&nbsp;Having the right radar system and algorithms, it is possible to enable all above mentioned use cases of CPD, SOD, SBR, and intrusion- and proximity alert with just one radar sensor per car.<h3 dir="ltr">Secure Face Authentication and Driver Monitoring</h3>A unique feature of in-cabin ToF cameras is 3D face authentication – securing your vehicle using facial recognition. Incorporating depth-sensing technology, as seen in smartphones and payment terminals, delivers the highest quality of anti-spoofing security. This functionality enables the real connected car, where a driver has seamless access to private data or personalized services like music streaming or any payment functionality – whenever there is the need to authenticate.&nbsp;Once a 3D ToF-based driver monitoring camera is installed for 3D face-ID, the same camera can also be used for the basic driver monitoring system (DMS) functionality to ensure drivers are alert to the road: to monitor the driver’s head movement, eye closure and gaze direction and to flag any distraction or signs of drowsiness.Furthermore, knowing the exact eye position by the 3D ToF data helps to optimize projection features like the optimal view onto a head-up display (HUD).<h3 dir="ltr">Personalized Comfort</h3>Once the vehicle has authenticated who the driver is, the system is able to adjust the vehicle's interior to that driver’s personal preferences. A ToF camera recognizes the driver, and the ICMS can then adjust the seat position, climate control, and entertainment settings to create a personalized and comfortable cabin space.&nbsp;<h3 dir="ltr">Enhanced Gesture Control</h3>While gesture control has been around for a while, it has been limited to a very narrow zone near the driver. A ToF sensor with higher resolution enables a wider field of view with enough spatial resolution to properly detect and track fingers enabling passengers to adjust entertainment settings etc, without touching an interface. It even allows interaction with smart surfaces and projections like HUDs and holographic visualizations.In particular for rear seat entertainment systems, gesture interaction can be very convenient and provides a kind of fun factor and the best entertainment content, like the possibility of gesture-controlled video games. Besides hand- and finger gestures, also body gestures can be used for a most convenient user experience. A ToF camera, for example detects if a passenger is reaching out to a certain area in the car and the interior light is illuminating just this area.It should be mentioned that depending on the use case the right camera specification and placement have to be considered.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNzA2NzkyNzE0ODg5LUlNQUdFUy0wMyAoMSkuanBnIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 300px;" class="fr-fic fr-dib">Combination of radar and ToF sensors enable the maximal amount of in-cabin monitoring use-cases.<h1 dir="ltr" id="isPasted">Infineon’s In-Cabin Solutions</h1>Infineon Technologies has paved the way for a transformative shift in automotive technology by introducing innovative products for in-cabin monitoring. Infineon’s automotive radar sensors and Time-of-Flight solutions are shaping the realm of in-cabin monitoring and detection systems, redefining safety, security, comfort, and user experience within vehicles.&nbsp;Infineon's XENSIV™ 60GHz radar transceiver, a powerful yet cost-effective innovation, sets the stage for advanced safety features (5). Operating in the 58 to 62 GHz frequency range, the BGT60ATR24 radar sensor family boasts two transmit, and four receive channels and a low-noise phase-locked loop. The radar is designed with an integrated anti-aliasing loop filter, finite state machine, and RX baseband with ADC ensuring high-performance data precision, which is crucial for safety features like occupancy detection. The BGT60ATR24AIP features Infineon’s antenna in package technology, enabling a very small footprint while reducing efforts at customer side to design antennas. The radar sensor is able to address numerous passive safety applications like left-behind child and pet detection, driver vital monitoring, and occupancy sensing due to its ability to sense micro motions.To complement the benefits of the radar sensor, Infineon offers its automotive-grade REAL3™ ToF sensors IRS2877A(S) (6). IRS2877A offers a VGA system resolution of 640 x 480 pixels arranged in a way that minimizes crosstalk while maximizing performance and achieving an image circle of only 4mm for the smallest possible lens- and as such, module sizes. Additionally, each pixel is equipped with a patented Suppression of Background Illumination (SBI) circuitry enabling the ToF cameras to operate in all lighting conditions and exhibit sunlight robustness.&nbsp;All of this is packaged in a highly minimized plastic package with a footprint of only 9x9 mm, making it fit seamlessly into the interior of a vehicle. This combination of compact size and impressive resolution opens the door to innovative automotive applications, including secure face authentication, driver monitoring and wide-field-of-view in-cabin sensing cameras. IRS2877AS is the ISO 26262 (ASIL-B) compliant variant to address functional safety requirements like smart airbags, the world’s first of its kind.The flexibility of both sensors allows for discrete integration within the cabin, ensuring their effectiveness without compromising aesthetics. Customer needs, operating conditions, and budgetary limitations determine the number and placement of sensors, optimizing coverage and enabling desired functionalities. Combining data from both sensors can achieve a robust and comprehensive In-Cabin Monitoring System.<h2 dir="ltr">Conclusion</h2>The use of radar and ToF sensors in In-Cabin Monitoring Systems represents a significant leap forward in automotive safety and user experience. Integrating features like occupant detection and fine-grained monitoring, ICMSs powered by these sensors have the potential to transform driving into an intelligent, safer, and more personalized experience. As sensing technologies continue to evolve, we can anticipate exciting improvements in the precision, range, and overall capabilities of ToF and radar sensors, paving the way for even more sophisticated applications as we head towards full autonomy.&nbsp;<h2 dir="ltr">References</h2>1. &nbsp; &nbsp;Soldatos J. Why Radar Sensors are Powerful Enablers for Intelligent IoT Applications [Internet]. [cited 2023 Sep 30]. Available from: https://www.wevolver.com/article/why-radar-sensors-are-powerful-enablers-for-intelligent-iot-applications2. &nbsp; &nbsp;Automotive News Europe [Internet]. 2022 [cited 2023 Oct 1]. How to make vehicles safer against hot car deaths. Available from: https://europe.autonews.com/guest-columnist/how-make-vehicles-safer-against-hot-car-deaths3. &nbsp; &nbsp;Hot Car Act 2021 [Internet]. 117th Congress (2021-2022) [cited 2023 Dec 15] https://www.congress.gov/bill/117th-congress/house-bill/31644. &nbsp; &nbsp;Euro NCAP. Euro NCAP roadmap 2025 [Internet]. Leuven; 2017 Sep p. 19. Available from: https://cdn.euroncap.com/media/30700/euroncap-roadmap-2025-v4.pdf5. &nbsp; &nbsp;Infineon Technologies. 60GHz radar sensors for automotive | Interior sensing - Infineon Technologies [Internet]. [cited 2023 Oct 2]. Available from: https://www.infineon.com/cms/en/product/sensor/radar-sensors/radar-sensors-for-automotive/60ghz-radar/6. &nbsp; &nbsp;Infineon Technologies. ToF 3D image sensors for automotive - Infineon Technologies [Internet]. [cited 2023 Oct 2]. Available from: https://www.infineon.com/cms/en/product/sensor/tof-3d-image-sensors/tof-3d-image-sensors-for-automotive/

As cars shift to automated driving, In-Cabin Monitoring Systems (ICMS) are vital for passenger safety and comfort. Incorporating Time-of-Flight cameras and radar sensors enables ICMS to detect occupants and their behaviors promising a safe and personalized automotive experience.

Steering Towards Safer Rides: The Role of Radar and ToF Sensors in In-Cabin Monitoring Systems (ICMS)

<h2 dir="ltr" id="isPasted">FREE REPORT:&nbsp;Reducing Human Driver Error and Setting Realistic Expectations with Advanced Driver Assistance Systems</h2>Thousands die or are injured each year in automobile crashes. Bringing automated driving systems technologies into the advanced driver assist systems (ADAS) and connected vehicle space will help humans drive more safely and better prepare us for automated vehicles (AVs).Learn more about ADAS and ADS implementation with the goal of reaching zero deaths and serious injuries by downloading this FREE report from SAE International (valued at $50).&nbsp;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNzAyMzIxNDMwMTE3LXNhZSBmcmVlIHJlcG9ydC5qcGciLCJlZGl0cyI6eyJyZXNpemUiOnsid2lkdGgiOjk1MCwiZml0IjoiY292ZXIifX19" style="width: 300px;" class="fr-fic fr-dib"><iframe src="https://c8056756.sibforms.com/serve/MUIFAIm7QnvQQ9ZyzkX--H5jNS-TSb9GWr5SQBXi_SUjRPpt67CBveq_yevZYMSeiJ-O1dwYw05f2kl-Q7sfNDRem1Y-03GXYZV4qkTbJeR_K_VpJzgMk_8Ry8fjyfgJ7fAMrCmcRHc1KXsSTuhIU5p5pBa3F1-TGDgOdQgcF-pU8cSTrl8JF2j2b9gl6-5e66Ro-rltcIrGxsRG" frameborder="0" scrolling="auto" allowfullscreen="" style="display: block; margin-left: auto; margin-right: auto; max-width: 100%; width: 540px; height: 740px;" class="fr-draggable" data-lf-form-tracking-inspected-kn9eq4roawkarlvp="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-lf-vimeo-playback-inspected-kn9eq4roawkarlvp="true">&nbsp;&nbsp;</iframe><hr><h2>Provizio promises its 5D Perception stack can safely compete with expensive lidar sensors at a fraction of the cost.</h2>"Safety first” is more than a catchphrase. For sensing company Provizio, it’s the only way the transportation industry should introduce autonomous vehicles. In Provizio’s view, using AV building blocks – technology such as automatic emergency braking and lane-keep assist – can be valuable in ADAS systems, but they should not be used to drive vehicles until the perception problem has been solved.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNzAyMjgyNDM3MTM3LXByb3ZpemlvLXJhZGFyLXN1cGVyLXJlc29sdXRpb24tZ2FsbGVyeS5qcGciLCJlZGl0cyI6eyJyZXNpemUiOnsid2lkdGgiOjk1MCwiZml0IjoiY292ZXIifX19" style="width: 300px;" class="fr-fic fr-dib">An example image using data taken from Provizio’s “super-resolution” radar sensor.<blockquote>“It’s not that we’re skeptical about autonomous driving, it’s just that we strongly believe that the industry has taken this wrong path,” Dane Mitrev, machine learning engineer at Provizio, told SAE at September 2023’s AutoSens Brussels conference.</blockquote>“The industry has looked at things the other way around. They tried to solve autonomy first, without looking at accident prevention and simpler ADAS systems. We are building a perception technology which will first eliminate road fatalities, then deliver next-generation ADAS – and then solve autonomy. We believe that’s the right order.”Obviously, the industry is in favor of AVs. A group of 11 mobility and automotive companies released a 157-page paper in 2019 called “Safety First for Automated Driving.” Those companies — Aptiv, Audi, Baidu, BMW, Continental, Daimler, FCA US LLC, HERE, Infineon, Intel and Volkswagen — used the paper to propose a non-binding organized framework focused on “the development, testing and validation of safe automated passenger vehicles,” but did not attempt to establish any actual limits on what companies could do as they developed AVs. In the years since, AV technology has continued to advance, but not with the mission to solve sensing and important safety issues before teaching the vehicles how to maneuver.Provizio’s solution is its 5D Perception driving platform, named for the way it uses five different inputs to sense the environment. There’s the 3D radar information of an object in space, plus velocity information, plus the fifth dimension: perception, which means AI embedded in the hardware. Mitrev said the final vision of this technology will be powered by radar and cameras, not light detection and ranging (lidar). Radar’s benefits are well known: the sensors are smaller (and thus simpler to integrate) and less expensive than lidar and can see in all weather conditions. For now, though, Provizio is working with lidar, especially around its hometown.<h3>Irish sensors are smiling</h3>Provizio is headquartered in Limerick, Ireland, and has offices in North Ireland and Pittsburgh, Pennsylvania. In late 2022, Provizio signed a deal with micromobility company Voi to test 5D perception on Voi’s scooters. Alongside potential OEM and Tier 1 partnerships he couldn’t discuss, Mitrev said Provizio also has a partnership with Jaguar Land Rover, supporting tests at a future mobility campus in Ireland.These real-world tests involve collecting data from lidar to train the new radar AI. Provizio synchronizes the lidar and radar sensors, then extracts value from the lidar data at training time, embedding it into the neural net and teaching the neural networks based on these data streams. Imagine lidar as an old professor teaching a young radar sensor a few things, but sooner or later, the student – Provizio’s radar – won’t need the teacher anymore.<blockquote>“We lean fully towards a lidar-less path,” he said. “Lidars should not be involved, even in [SAE Level 5] vehicles. They’re not necessary.”</blockquote>The same is not true for cameras. To understand semantic information such as traffic signs, Provizio’s system uses cameras to augment the radar data.“Provizio is a perception company, first of all,” Mitrev said. “We are not a radar company. We’re not a car manufacturer. We’re a perception company, we have this radar and we have a perception platform that fuses radars and cameras and provides this low-cost solution.”Provizio was founded by Barry Lunn following the acquisition of his company Arralis, which focused on millimeter-wave communication technology for satellite communications and aerospace markets. Provizio’s radar technology grew out of radar work Lunn was familiar with in the aerospace industry. Instead of a commercial, off-the-shelf radar unit, Provizio is “redefining radars,” Mitrev said, by adding AI neural networks to the radar GPUs so all critical decisions can be made on the radar itself with less than five milliseconds latency to make those decisions. He said Provizio’s goal for its 5D radar is to see up to 600 m (1,969 feet) in 360 degrees in all weather conditions.<blockquote>“Once we have this 5D perception, there is literally no reason to build any other system that will do ADAS or autonomy,” he said, adding that accident prevention is “something tangible that we can solve in the next one, three-to-five, years.”</blockquote>At CES 2023, Provizio said it planned to deliver the first of its 5D Perception platforms by 2025. Provizio’s commercial strategy relies on licensing its technology to Tier 1 suppliers and OEMs. Once better sensors are in more vehicles that accurately understand the world around them, that’s when we can start letting vehicles drive themselves, Mitrev said.“The end goal is mass adoption, to have our 5D perception on all vehicles or a lot of vehicles worldwide, then we bring down the road deaths,” he said. “We believe that this is the right path. The industry has taken this the other way around. [Starting by building a self-driving car] is just too complex, let alone with only cameras, as some companies claim.”

Provizio offered demo drives of its technology on the road in Las Vegas during CES in January 2023. These images show some of what the sensors saw during the drive, along with some of Provizio’s identifying data. (Provizio)

"Safety first” is more than a catchphrase. For sensing company Provizio, it’s the only way the transportation industry should introduce autonomous vehicles.

Autonomus safety with radar, not LiDAR

Sponsor interview with Theresa Hackl, Application Marketing Engineer, Komei Takura, Senior Business Development Manager for Mobility and 
Yoichi Murakami, Senior Product Manager for Function Devices at Murata. 

2023 Autonomous Vehicle Report Interview: Building Trust in Autonomous Driving - Navigating Future Reliability and Milestone Achievements

The demand for compact yet energy-efficient radar sensors for remote vital sign monitoring is witnessing an exponential rise in the healthcare industry for several reasons.

Contactless Measurement of Heart Rate and Respiration Rate: Transforming Healthcare with Radar Sensors

Explore the key differences, advantages, and applications of lidar and radar technologies in modern engineering projects.

Lidar vs. Radar: Comprehensive Comparison and Analysis

It takes a radar out of the ordinary to catch a drone in flight. It is even harder to detect a drone that is hovering in the same place, because it quickly disappears in the background noise. But a new radar system&mdash;developed by researchers from DTU Space in collaboration with the Danish company Terma&mdash;can do both and more to boot.The radar has a high resolution and a wide field of vision, and it can track many drones simultaneously. Drones are otherwise difficult to spot, because they can be tiny and come from all directions. Moreover, they are often made of plastic materials that do not reflect radar waves very well.&ldquo;There is a large market for detecting drones, for example in military contexts and at airports,&rdquo; says Professor J&oslash;rgen Dall from DTU Space, who heads the radar project. He also mentions the problems that the Swedish authorities have had with illegal drone flights. Especially at the beginning of 2022, drones were repeatedly observed over nuclear power plants, military areas, airports, and royal palaces.To avoid accidents at airports, protect critical infrastructure, and keep military secrets, etc., there are many places where drones are not allowed to fly. The first step towards combating illegal drone flying is to detect, track, and preferably also classify the drone. And here the new radar can help.<h2>Many antennas provide higher resolution</h2>In general, a radar works by emitting a microwave signal that is reflected by an object, and the echo is then picked up and compared with the outgoing signal. Knowing that the signal moves at the speed of light, it is easy to calculate the distance to the object. You just have to measure how long it has been under way.This is easy in theory, but it is more difficult in the real world, especially if you want to know not only the distance to an object, but also its exact position in three dimensions, as well as its speed. But here the researchers from DTU Space exploit the great advantage of having a radar which has not just one antenna that is used to send and receive signals, but instead a total of 16 antennas.The principle of using multiple antennas is called MIMO, which stands for multiple-input multiple-output. The principle is especially known from wireless communication, where the advantage is first and foremost to ensure a high bandwidth.Without MIMO technology in the latest WiFi standards and mobile networks (4G and 5G), the speed of data transfer to and from the laptop and mobile phone would be somewhat lower than it is today. The DTU researchers set out to examine whether the technology with multiple antennas can also be used to improve radar systems, and this turned out to be the case.<h2>Works without rotating</h2>&quot;With MIMO, we can see in all directions concurrently within a fairly wide angle range&mdash;for example 120 degrees&mdash;and we can get a good horizontal angle resolution in a relatively low-cost way without rotating the radar,&rdquo; says J&oslash;rgen Dall and continues:&ldquo;Our radar has eight transmitters and eight receivers. If all the transmitters sent the same signal at the same time, we would just get one large antenna sending a signal in a specific direction, but, instead, we make sure that the transmitters either send the same signal in a staggered manner or send different signals.&rdquo;&quot;Each of the eight signals is collected and separated from each other by all eight receivers, which gives us 64 virtual channels in total, even though we only have 16 physical channels.&rdquo;When a drone is hit by a signal from a transmitter, the signal is reflected back to all eight receivers, and&mdash;based on the timing of the echo&mdash;the distance and direction to the drone can be calculated. But with eight transmitters and receivers positioned in just the right way relative to each other, the position and speed of the drone can be determined much more accurately.<h2>Range may be increased</h2>If the drone is close, it even becomes possible to identify the type. So-called micro-doppler signatures&mdash;which are caused by the movements of the rotor blades&mdash;can reveal what type of drone it is.The radar project has been running since 2018 and has now resulted in a demonstration model that clearly shows that the concept works. Another MIMO radar is being built. The range of the prototypes is just 100 metres, because a longer range requires higher power, a transmission permit from the authorities, as well as somewhat more expensive amplifiers. Initially, the project focused on showing that the technology can be used, and the range can easily be increased in later versions.J&oslash;rgen Dall also emphasizes that MIMO radars can be used for other purposes than detecting small, flying objects. The primary purpose of the project is to conduct research into radar technology, and drone detection was an appropriate application in this connection.The project will continue with two PhD students attached and a third on the way, and it is primarily funded through a grant of DKK 5.8 million from the Thomas B. Thrige Foundation. If Terma chooses to continue with the technology for actual product development and commercialization of MIMO radars, it is possible that these systems will contribute to protection of airport security against threats from the ground as well as the air, as a competence extension to Terma&rsquo;s airport radars worldwide.

A new type of high-resolution radar developped at DTU Space looks in many directions concurrently. Photo: Lasse Lehmann, DTU.

Researchers from DTU Space have developed a new type of high-resolution radar that looks in many directions concurrently.

New radar system can detect drones

This is the first article in a <a href="https://www.wevolver.com/article/co2-sensors-are-an-iot-applications-must-have" rel="noopener noreferrer" target="_blank">6-part series</a> exploring the technologies enabling the cutting-edge IoT.&nbsp;&nbsp;More than twenty years after the introduction of the term &ldquo;Internet of Things&rdquo; (IoT), the world is gradually becoming connected by millions of sensors and devices. IoT devices are already used for better- and smarter living, saving costs and improving the quality of life.<style type="text/css" id="isPasted">
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</style>The market demand for smart devices and their applications is experiencing dynamic growth as more and more consumers are looking to leverage the comfort, energy efficiency, and security benefits of smart technologies. According to <a href="https://www.statista.com/statistics/976313/global-iot-market-size/" target="_blank">Statista market research the global IoT&nbsp;market</a> will be worth around 1.6 trillion US dollars by 2025.&nbsp;One of the factors that propels this market growth is the emerging wave of &ldquo;intuitive sensing&rdquo; applications, which enable humans to interact with smart devices in a more natural and seamless way than ever before. The deployment of intuitive sensing relies on a range of non-intrusive sensing systems, which endow IoT applications with novel perceptive capabilities. Intuitive sensing systems enable IoT applications to &ldquo;see&rdquo;, &ldquo;hear&rdquo;, &ldquo;smell&rdquo;, &ldquo;perceive&rdquo; and understand the surrounding environment. In this way, they open new horizons for IoT technology in a variety of areas such as smart homes, security and industry.<h2>Introducing Radar Sensors</h2>In the scope of IoT systems and applications, a radar sensor is a device that is capable of sensing and potentially tracking one or more objects. In contrast to other Radio Frequency (RF) based passive/active wireless sensor systems, radar sensors are active, i.e., they can send out pulses and receive their echoes. Radar technology makes it possible to estimate the target&rsquo;s speed, direction, and range (i.e., distance from the radar transmitter/receiver). Moreover, there are radar sensors that can detect small movements and even the presence of humans due to their high sensitivity towards the smallest motions.Overall, the key advantages of highly sensitive radar technology for IoT applications include:&nbsp;<ul><li>Small size: Radar sensors have a small footprint in the size of the overall IoT system. Therefore, they enable the development of IoT systems of relatively small size. Their small size boosts their unobtrusive operation so as not to disturb or distract users.</li><li>Robustness: &nbsp;Radar sensors work very well under different environmental or climate conditions. For instance, their operation is not essentially affected by variations in temperature or lighting conditions. &nbsp;</li><li>Product Design Flexibility: One of the key features of radar sensors is that they can be concealed under product covers, which increases the design and deployment flexibility for IoT products. Specifically, radars emit RF signals at high frequencies (e.g., 24GHz), which can pass through most materials (e.g., plastic, glass, and wood). Hence, they can provide accurate readings for objects behind walls or obstacles.&nbsp;</li><li>Sensitivity: &nbsp;Radar sensors can detect very small motions (e.g., breathing movements), which enables a host of interesting IoT use cases like sensing of human presence and of vital signs such as heartbeats.</li><li>Power efficiency: Radar sensors consume relatively little power and therefore allow for great battery life. Hence, they enable IoT applications with considerable autonomy and energy efficiency.</li></ul><h2>Benefits of Radar Sensors for Motion Detection</h2>Based on the above-listed properties, radar sensors can be used in many possible scenarios. However, their most common application is to detect movements and the presence (or absence) of targets such as people, vehicles, and animals. &nbsp;Motion detection is an important capability for many IoT applications, including security monitoring, energy management, human-computer interaction (e.g., gesture recognition), and medical monitoring i.e., tracking of heart and respiration rate.&nbsp;The technology traditionally used for motion detection is passive infrared (PIR) sensors. Passive infrared motion sensors have been commonly used for detecting people moving around a space. They have been around for decades and have become ubiquitous i.e., they can be found in lighting fixtures, security systems, and automatic doors, among other places.However, there are significant limitations associated with the deployment and use of PIR sensors, such as false alarms due to pets and other sources of infrared radiation in the environment, interference from other sources that operate on the same frequency range (e.g., TV remote control), limited sensing range and lack of directional information. Specifically, PIR sensors require a direct line of sight to detect motion, and their detection range is limited to the area directly in front of the sensor. Also, they usually require a significant movement in order to be triggered. For instance, it&rsquo;s quite common for users to wave their hand in front of a PIR sensor in order to ensure that a smart home command is understood. &nbsp;Radar technology alleviates the above-listed problems and limitations for motion detection. For example, radar sensors enable IoT applications to reliably tell the presence or absence of people in a room, independently of how fast and how much they are moving. Moreover, radar sensors are so precise that they can detect a human&#39;s breathing or heartbeat. This is not possible with PIR sensors that can only detect temperature changes caused by objects passing through their field of view.&nbsp;<h2>60GHz Radar Technology</h2>Radar sensors operate in different frequencies. A rich set of radar technologies operate at 24GHz with the bandwidth for FMCW (Frequency Modulated Continuous Wave) radar operations covering up to 250MHz within the regulated ISM (Industrial, Scientific, and Medical) band. This technology is extensively used in outdoor use cases, since it offers high detection range and is very robust to environmental influences (e.g., humidity).While the 24GHz band is limited to the ISM band, there is a 7GHz unregulated bandwidth available around 60GHz. Hence, 60GHz radar technology has been developed to help create more powerful applications and products, notably applications requiring large bandwidth operations and close proximity sensing applications. Specifically, 60GHz radar technology can detect motions and complex gestures at a finer level of granularity and with better accuracy than 24GHz technology. &nbsp;This makes 60GHz technology an ideal choice for use in applications like occupancy sensing, human tracking, and segmentation, materials classification, as well as monitoring of human vital signs at a distance. Moreover, the micro-motion detection capabilities of 60GHz radar technologies make it appropriate for the emerging wave of Augmented Reality (AR) and Virtual Reality (VR) applications that will empower the Metaverse. This is the reason why 60GHz radar chipsets are already being integrated into HMDs (Head Mounted Displays) by various manufacturers.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjUzMzkwMDYyMjk5LWxhdXJlbnMtZGVya3MtYkNkSXg1TGpyWW8tdW5zcGxhc2ggKDEpLmpwZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 788px;" class="fr-fic fr-dib">60GHz radar chipsets are already being integrated into HMDs (Head Mounted Displays) by various manufacturers.&nbsp;<h2>Radar Technology in Smart Home Applications</h2>Smart homes represent one of the fastest-growing segments of the IoT market. It is also the segment where radar technology acts as a catalyst for improving applications&rsquo; functionalities, accuracy, energy consumption, and cost. Specifically, the emerging availability of low-cost, low-power radar sensors enables a new generation of smart home applications ranging from enhanced security and safety through to improved convenience and comfort. Some of the most prominent examples of radar-enabled functionalities in smart homes include:<ul><li>Automatic Door Control: Radar sensors for intuitive sensing provide not only information on motion but also on approaching and departing movements. This can enable automatic door control applications, where doors open only if a target is continuously approaching, and not when other kinds of motion are detected.</li><li>Presence/Absence Detection: When equipped with radar sensors, smart devices can sense the presence or movement of people, which enables a wide range of optimization applications. For instance, when no one is present, a radar-based smart device can automatically switch to sleep mode and save energy.</li><li>Segmentation and Tracking: &nbsp;Radar sensors can add many smart functionalities to devices such as sound systems. For instance, sound systems could track the position of the listener and continuously optimize volume and sound parameters accordingly.</li><li>Elderly Care Systems: Radar technology enables the development of innovative elderly care applications. For instance, they empower bed-exit systems that can be used to tell if a person has got out of bed and not returned within a few minutes. Similarly, radar sensors enable chair exit systems that determine whether a person has left their chair and not returned within a certain time.</li><li>Heating Control Systems: Radars enable underfloor heating system control that determine whether someone is in the room, turning the heating on or off accordingly. &nbsp;In addition, they can track the distance and the position of a person in a room towards adjusting the fan speed as well as the direction of the blades of the room air conditioner unit. Such use cases improve the occupants&rsquo; comfort while boosting environment performance and sustainability.</li><li>Fall Detection: &nbsp;Radar-based systems can be used for fall detection. In this case, the radar is typically mounted on a wall or ceiling and is continuously emitting modulated signals. When a person falls, their body rotates, causing shifts in the reflected waves. The radar system can then detect these shifts and record them as a fall event.</li><li>Vital Signs Monitoring: Similar radar configurations can be also used to monitor breathing patterns and heart rates. Over time, this information can be used to detect deviations in the heartbeat pattern that could indicate cardiac arrhythmia or other problems. Heartbeat pattern detection enables a host of innovative lifesaving applications in the areas of infant care (e.g., identification of irregularities in heath rate) and elderly care.&nbsp;</li></ul>Most of these functionalities can be captured based on body movement at a distance, even in poor lighting conditions. Moreover, they are delivered in a non-intrusive manner for the home&rsquo;s occupants. The latter can move freely around the house without tripping false alarms from optical motion detectors mounted on walls or ceilings.&nbsp;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjUzMzg5NDExMjc1LXJhZGFyIHZpdGFsIHNpZ25zLmpmaWYiLCJlZGl0cyI6eyJyZXNpemUiOnsid2lkdGgiOjk1MCwiZml0IjoiY292ZXIifX19" style="width: 788px;" class="fr-fic fr-dib">Radar has applications in vital signs monitoring. Image credit:&nbsp;<a href="http://nature.com/articles/s41598-021-03069-2" rel="noopener noreferrer" target="_blank">Park.J et al.</a><h2>The Era of Intuitive Sensing</h2>Latest advances in radar technology open new opportunities for pervasive and user-friendly IoT applications. &nbsp;These opportunities lead to the era of intuitive sensing, which is characterized by simple, effortless, and natural interactions with all kinds of smart devices. Intuitive sensing is a powerful enabler of non-obtrusive applications that make our lives easier, safer, greener, and more efficient.&nbsp;<a href="https://www.infineon.com/cms/en/product/technology/intuitive-sensing/" target="_blank">Infineon is among the industry&rsquo;s leaders in intuitive sensing solutions</a> leveraging on its autonomous, small-sized, user-friendly radar solutions, which include both 24GHz and <a href="https://www.infineon.com/cms/en/product/sensor/radar-sensors/radar-sensors-for-iot/60ghz-radar/?utm_source=wewolver&utm_medium=referral&utm_campaign=202205_glob_en_pss_radar&utm_content=article&utm_term=radar_sensor#!trainings" target="_blank">60GHz solutions</a>. &nbsp;The company&rsquo;s XENSIV&trade; family of sensors includes a rich set of exceptionally precise radar sensors, which are the perfect fit for various customer applications in automotive, industrial, and consumer markets. In all these markets, XENSIV&trade; deployments deliver fast time-to-market and <a href="https://www.infineon.com/cms/en/about-infineon/energy-efficiency-technologies/smart-home-and-building/#!slider" target="_blank">significant energy efficiency</a>. As such they are a solid choice for improving deployers&#39; bottom lines while helping them achieve ambitious sustainability targets.Overall, recent advances in radar technology make it a powerful enabler of the next generation of accurate, user-friendly, and intuitive IoT applications that deliver great performance and handle environmental impact intelligently. In this context, IoT deployers and solution integrators cannot afford to ignore radar technology when designing and developing their applications.Learn more about Infineon&rsquo;s autonomous radar sensor for IoT applications in <a href="https://www.infineon.com/cms/en/product/promopages/mobile-world-congress/?redirId=179041&utm_source=wewolver&utm_medium=referral&utm_campaign=202205_glob_en_pss_radar&utm_content=article" target="_blank">this</a> on-demand radar webinar.This is the first article in a <a href="https://www.wevolver.com/article/co2-sensors-are-an-iot-applications-must-have" rel="noopener noreferrer" target="_blank">6-part series</a> exploring the technologies enabling the cutting-edge IoT.&nbsp;&nbsp;The second article&nbsp;<a href="https://www.wevolver.com/article/co2-sensors-are-an-iot-applications-must-have" rel="noopener noreferrer" target="_blank">provides a deep look at the role of Co2 sensors.&nbsp;</a>The third article looks at how&nbsp;<a href="https://www.wevolver.com/article/tof-3d-image-sensors-are-changing-the-way-we-engage-with-photography-and-mixed-reality" rel="noopener noreferrer" target="_blank">Time of Flight (ToF) sensors are used for this purpose and are changing the way we can interact with VR, and other video technologies.</a>The forth article looks at how&nbsp;<a href="https://www.wevolver.com/article/predictive-maintenance-using-smart-sensors-to-get-the-most-out-of-your-assets" rel="noopener noreferrer" target="_blank">industrial enterprises are moving to a new approach to asset management, namely predictive maintenance by leveraging powerful new sensors and data.</a>The fifth article explains&nbsp;<a href="https://www.wevolver.com/article/high-snr-microphones-are-transforming-laptops-into-all-round-communication-hubs" rel="noopener noreferrer" target="_blank">how MEMS microphones can deliver high-quality sound in an ultra-small form-factor.</a><h1 dir="ltr" id="isPasted">About the sponsor: Infineon Technologies </h1>Infineon Technologies AG is a world leader in semiconductor solutions that make life easier, safer and greener. Microelectronics from Infineon are the key to a better future. With around 50,280 employees worldwide, Infineon generated revenue of about &euro;11.1 billion in the 2021 fiscal year (ending 30 September) and is one of the ten largest semiconductor companies worldwide. To learn more click&nbsp;<a href="https://www.infineon.com/" rel="nofollow" target="_blank">here.</a><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjUzMzg2MjMyOTI3LUluZmluZW9uIGJvdHRvbSBsb2dvLmpwZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 300px;" class="fr-fic fr-dib">

Article #1 of the Enabling IoT Series. "Intuitive sensing” applications enable humans to interact with smart devices in a more natural and seamless way.

Why Radar Sensors are Powerful Enablers for Intelligent IoT Applications

<h2 dir="ltr" id="isPasted">What is RADAR?</h2>The&nbsp;full form&nbsp;of&nbsp;RADAR&nbsp;is Radio Detection And Ranging. It is an umbrella term for any remote sensing device used to detect the presence, position, size and speed of objects with the help of radio waves.The development of RADARs was spread out over several years between the late 1800s and mid-1900s. Similar variations of the technology were developed independently by many countries around the same time. Hence, it is difficult to accredit the invention to an individual researcher or a group of researchers.&nbsp;Having said that, the contribution of Maxwell, Hertz, Marconi, Hülsmeyer and Watt is considered quite significant in the field.<h2>How does RADAR work?</h2>RADAR’s full form tells us that the technology is concerned with detecting objects with radio waves. Similar to how we see objects after they get illuminated by light with the help of our eyes, RADARs use a combination of transmitter and receiver to ‘see’ what’s around them.The transmitter emits the radio waves in the direction of the target in the form of continuous signals or intermittent pulses. The waves travel through the medium in which the RADAR system and the target is present until they finally hit the target and get reflected as an echo.The reflected waves travel back to their source and are detected by a receiver. This not only tells us that an object is present in the line of sight but also gives us an idea about how far it is. Since the speed of propagation of radio waves in various media is already known, by measuring the time delay between the transmission and reception of the radio waves, the distance between the source and target can be computed.Only a fraction of radio waves are picked up by the receiver as most of the energy is lost either during propagation or due to scattering. The is the reason why RADARs need a powerful transmitter, a sensitive receiver and a capable digital signal processor to function properly.&nbsp;<div class="fr-img-space-wrap"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjM1NTg1OTExMjIzLXJhZGFyX3N5c3RlbS53ZWJwIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 300px;" class="fr-fic fr-dib">A functional block diagram of a RADAR system. Reproduced with permission from Richards, 2014 </div>In addition to finding out how far the objects are, RADARs can also be used to determine how fast the objects are moving towards or away from the signal source. When we transmit radio waves at an object that is moving towards us, the reflected radio waves tend to get compressed, causing an increase in their frequency. The effect is the opposite in case if the object is moving away from us. This phenomenon is known as the doppler effect and helps us calculate the speed of moving objects by observing a change in the frequency of radio waves during the process.Since the complete working of a RADAR is based on the measurement of time delay between sending and receiving the signal, it is critical for the transmitter and receiver to be in proper sync, which requires sophisticated control equipment.&nbsp;In practice, RADARs need to be designed after carefully considering the required resolution and range. Radio waves at high frequencies offer excellent resolution but are susceptible to attenuation and scattering, which limits their range. On the other hand, low-frequency radio waves have a higher range but have poor resolution. It’s a trade-off between range and resolution that engineers need to make based on the requirements of the particular application the design is being made for.&nbsp;<h2 dir="ltr" id="isPasted">Applications of RADAR</h2>A surprisingly large number of applications of RADARs exist. As the technology has been around for a long time now, it has become a reliable, economical, efficient and commonly available technology for detecting objects from a distance.Air Trafic Control: RADARs are used in both passenger aircraft and ground control stations for navigation purposes. The technology also warns the pilots and air traffic control about extreme or unfavourable weather conditions.Military applications: Fighter jets use RADAR to find out their altitude and detect the presence of any other physical structure or aircraft nearby. RADARs are also used in ships and submarines for navigation and the detection of mines.Applications in Automobiles: Autonomous vehicles use RADAR and other technologies like LIDAR and cameras as sensors to create a virtual 3D profile of their surroundings. Usually, high-frequency RADARs are used in cars as accuracy is the priority over range. These devices are the eyes of autonomous vehicles. To read more about the similarities and differences between LIDAR and RADAR, check out our article on <a href="https://www.wevolver.com/article/lidar-vs-radar-detection-tracking-and-imaging" target="_blank">LIDAR vs. RADAR: Detection, Tracking, and Imaging</a>. Alternatively, you can read our report on <a href="https://www.wevolver.com/article/2020.autonomous.vehicle.technology.report" target="_blank">Autonomous Vehicle Technology</a> to know about the latest trends in the autonomous vehicle industry.Speed cameras: On roads, RADAR speed cameras and handheld RADAR detectors can be used to keep the speed of vehicles in check.Apart from the applications mentioned above, RADARs are also extensively used in space research, weather forecasting, and numerous other remote sensing applications.&nbsp;Even though the applications of RADAR span several different systems of different sizes, the basic principle behind the working of the technology remains the same.<h2 dir="ltr" id="isPasted">Conclusion</h2>Back when RADAR systems were first developed, operating them was extremely complicated. The operator had to manually tune the operating frequency based on the environmental conditions to reduce the noise. The advancements in Artificial Intelligence and Digital Signal Processing have made it possible to automate a lot of things that previously required human intervention. Cognitive RADARs learn from their experiences to adapt to the environment and improve performance over time. Cognitive RADAR along with phased array RADARs are the future and among the hottest areas of research in signal processing.The advancements in RADAR and its integration with other notable detection technologies is all set to revolutionise remote sensing forever. This will open up a whole new world of possibilities and applications in various different fields of engineering.<hr><h2 dir="ltr" id="isPasted">References</h2>[1] Scheer, J. (2012). Principles of Modern Radar: Advanced Techniques, Volume 2. United Kingdom: Institution of Engineering and Technology.[2] Michael Parker, Chapter 16 - Radar Basics, Editor(s): Michael Parker, Digital Signal Processing 101, Newnes, 2010, Pages 191-200, ISBN 9781856179218, <a href="https://doi.org/10.1016/B978-1-85617-921-8.00020-1" target="_blank">https://doi.org/10.1016/B978-1-85617-921-8.00020-1</a>.[3] H. Zhu, Z. Zhu, F. Su and J. Zhang, "New Algorithms in Cognitive Radar," 2018 11th International Congress on Image and Signal Processing, BioMedical Engineering and Informatics (CISP-BMEI), 2018, pp. 1-4, doi: 10.1109/CISP-BMEI.2018.8633239.[4] Fenn, Alan &amp; Temme, Donald &amp; Delaney, William &amp; Courtney, William. (2000). The Development of Phased-Array Radar Technology. Lincoln Lab. J.. 12.

Find out the full form of RADAR, its working principle, applications, latest research topics and more in this brief article on one of the most widely used remote sensing technology.

RADAR: Full form, working, and applications

<h2 dir="ltr">Introduction</h2>LiDAR and RADAR are both remote sensing devices that are often used for the detection, tracking, and imaging of various objects.Both sensors have assisted measurement in a lot of fields, including environmental research, space exploration, and medical discovery.While they&rsquo;re used across a broad range of industries, LiDAR and RADAR are stirring up a buzz for their functionality in the autonomous vehicle space. The discussion around which one is better has plagued the industry for a while.Most manufacturers choose LiDAR sensors as their top sensing device. On the other hand, Elon Musk, Tesla&rsquo;s CEO and a central figure in the industry have <a href="https://arstechnica.com/cars/2019/08/elon-musk-says-driverless-cars-dont-need-lidar-experts-arent-so-sure/" target="_blank">shown his preference for RADAR</a> on multiple occasions.Self-driving vehicles need to be aware of their surrounding environment. Often, the system that enables object detection in autonomous vehicles includes a variety of sensing devices connected through a <a href="https://www.wevolver.com/article/sensor-fusion-everything-you-need-to-know-" target="_blank">sensor fusion algorithm</a>, including LiDAR, RADAR, ultrasonic sensors, and cameras.While they have overlapping goals, the simple change of the type of wave used makes their capabilities vastly different from one another.<h2 dir="ltr">What is LiDAR?</h2>LiDAR stands for light detection and ranging or laser imaging, detection, and ranging. While it&rsquo;s a fairly new concept compared to RADAR, it&rsquo;s been around since the discovery of lasers in the 1960s.There are two types of LiDAR sensing devices, airborne- and ground-based.Ground-based LiDAR uses lasers with a wavelength of 500 - 600 nm and is used in various applications, such as landslide studies or obstacle detection in autonomous vehicles. Airborne-based LiDAR, on the other hand, uses lasers with a wavelength of 1000 - 1600 nm and mostly used to collect terrain data. (Dong and Qi Chen, 2017)LiDAR systems are dependable because they&rsquo;re capable of measuring an environment with high accuracy and producing a 3D image based on the results.<h3 dir="ltr">How does LiDAR work?</h3>The lasers used to detect objects in a LiDAR can either be discrete or continuous.LiDAR sensors that use continuous waves use the phase difference of the return signal to determine the distance and characteristic of the object. For pulsed waves, we&rsquo;re more interested in the amplitude of the transmitted and received signals to create a point of cloud that reflects the detected object. (Beland, 2019)In measurement, full-waveform signals are often used in forestry, while pulsed signals have more use in other fields.A LiDAR system mainly consists of a light source and a receiver or sensor. The source beams out light or laser, which bounces off the target and back towards the LiDAR system, where the sensor catches the pulse.To determine the precise distance of an object, the LiDAR system calculates the time interval between the emittance of the laser and when it&rsquo;s received, taking the speed of light into account.On its own, LiDAR can catch the position, size, and shape of an object relative to the LiDAR system. However, LiDAR sensors are often paired with a GPS, an IMU sensor, or a camera to enhance their capabilities.<h2 dir="ltr">What is RADAR?</h2>RADAR stands for Radio Detection and Ranging. Just as its name suggests, RADAR&rsquo;s working principle is almost identical to LiDAR, except it uses radio waves instead of lasers or light.Radio waves have a much longer wavelength compared to light waves, making radars able to cover longer distances compared to LiDAR devices. The frequency and type of radio waves used depend on the requirement of your measurement device.<table style="width: 100%;"><tbody><tr><td style="width: 33.3333%; text-align: center;">RADAR Band</td><td style="width: 33.2487%; text-align: center;">Frequency (GHz)</td><td style="width: 33.3333%; text-align: center;">Wavelength (cm)</td></tr><tr><td style="width: 33.3333%; text-align: center;">Millimeter</td><td style="width: 33.2487%; text-align: center;">40-100</td><td style="width: 33.3333%; text-align: center;">0.75-0.30</td></tr><tr><td style="width: 33.3333%; text-align: center;">Ka</td><td style="width: 33.2487%; text-align: center;">26.5-40</td><td style="width: 33.3333%; text-align: center;">1.1-0.75</td></tr><tr><td style="width: 33.3333%; text-align: center;">K</td><td style="width: 33.2487%; text-align: center;">18-26.5</td><td style="width: 33.3333%; text-align: center;">1.7-1.1</td></tr><tr><td style="width: 33.3333%; text-align: center;">Ku</td><td style="width: 33.2487%; text-align: center;">12.5-18</td><td style="width: 33.3333%; text-align: center;">2.4-1.7</td></tr><tr><td style="width: 33.3333%; text-align: center;">X</td><td style="width: 33.2487%; text-align: center;">8-12.5</td><td style="width: 33.3333%; text-align: center;">3.75-2.4</td></tr><tr><td style="width: 33.3333%; text-align: center;">C</td><td style="width: 33.2487%; text-align: center;">4-8</td><td style="width: 33.3333%; text-align: center;">7.5-3.75</td></tr><tr><td style="width: 33.3333%; text-align: center;">S</td><td style="width: 33.2487%; text-align: center;">2-4</td><td style="width: 33.3333%; text-align: center;">15-7.5</td></tr><tr><td style="width: 33.3333%; text-align: center;">L</td><td style="width: 33.2487%; text-align: center;">1-2</td><td style="width: 33.3333%; text-align: center;">30-15</td></tr><tr><td style="width: 33.3333%; text-align: center;">UHF</td><td style="width: 33.2487%; text-align: center;">0.3-1</td><td style="width: 33.3333%; text-align: center;">100-30</td></tr></tbody></table>RADAR frequency bands (Parker, 2017)The discovery of RADAR preceded LiDAR, with the first known application of RADAR dating back to the early 1900s. RADAR systems are mainly used for tracking, detection, and 2D imaging in various industries, such as <a href="https://link.springer.com/book/10.1007%2F978-3-030-05093-1" target="_blank">environmental studies</a>,&nbsp;military defenses, and the development of smart buildings.<h3 dir="ltr">How does RADAR work?</h3>Similar to LiDAR, RADAR systems have two main components: a transmitter and a receiver. Here&rsquo;s a schematic of a modern RADAR system. (Richards, 2014) <div class="fr-img-space-wrap"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjE4ODIxODAxNjE1LVJhZGFyX3NjaGVtYXRpYyAoMSkucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" style="width: 589px;" class="fr-fic fr-dib" alt="Schematic of a RADAR system">Schematic of a RADAR system. Reproduced with permission from Richards, 2014&nbsp;</div>The radio waves used by a radar system can also be continuous or pulsed, which are the more frequent option.The transmitter and antenna in radar work together. The transmitter generates an electromagnetic wave, and the antenna sends out the wave through a medium.&nbsp;Then, the signal travels through the medium and is reflected by the target back to the RADAR system, which accepts the reflected radio wave through a receiver. The RADAR processes the radio wave and determines the distance relative to the system by using the time interval between the transmission of the signal and the time when the reflected signal is received.A RADAR system uses an antenna to transmit radio signals.Depending on the application of the RADAR, the frequency of the signal transmitted will vary (Parker, 2017). The frequency of your RADAR decides the limitations and capabilities of your RADAR system, such as range, wavelength, and antenna size.Systems with higher frequencies have lower power, higher attenuation, and more granular detection, which makes them perfect for short-range applications that need a higher resolution, such as in autonomous vehicles.<h2 dir="ltr">LiDAR vs RADAR: Which technology is better?</h2>While LiDAR and RADAR have identical goals and principles, the type of wave used by both systems created a whole new level of difference between them.Rather than which one is better, LiDAR and RADAR systems have their own place in your system with their advantages and disadvantages.<h3 dir="ltr">Accuracy</h3><div class="fr-img-space-wrap"><img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjE4ODE0NjgyNTk0LWxpZGFyX3ZzX3JhZGFyLnBuZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 636px;" class="fr-fic fr-dib" alt="LiDAR vs RADAR accuracy comparison">A comparison of LiDAR&#39;s and RADAR&#39;s accuracyAs you can see from the image above, images formed through a LiDAR system are crisper and much more detailed than ones formed through RADAR.</div>LiDAR uses light signals that work in the nanometer range, making LiDAR systems much more accurate and precise than RADAR systems. A lower wavelength also means that a LiDAR system can detect smaller objects, the size of targets, and create 3D images of the target. (Ryde and Hillier, 2009)On the other hand, the resolution of RADAR images is limited by the size of the antenna used. Antennas with a bigger size produce waves with higher frequencies, resulting in images with higher resolution. Keep in mind that the requirements for your antenna also depend on the limitations of your measurement system.In short, LiDAR is your best choice when you need to create a detailed image, while RADAR is better when constantly detecting the distance to the target is more important for your use case.<h3 dir="ltr">Reliability</h3>While RADAR&rsquo;s accuracy leaves much to be desired, it&rsquo;s much more reliable than LiDAR.LiDAR uses light waves as a medium and is easily affected by the medium itself. For example, moisture in the atmosphere affects the performance of a LiDAR system. LiDAR systems don&rsquo;t perform as well in bad weather, such as in the rain, fog, or snowstorm.Furthermore, most LiDAR used in autonomous vehicles uses a rotating device to shoot laser pulses, which means regular maintenance is necessary to keep it working well. However, recently there are more and more options for solid-state LiDAR systems, so this might not be a concern for much longer.RADAR, on the other hand, uses radio waves that have a much bigger wavelength, so it has enough power to cover longer distances than LiDAR.Radio waves also have lower attenuation, which allows them to travel minimally disturbed even in poor weather. When sensors that rely on the principle of optics are compromised, RADAR is an excellent choice as a substitute, even with its low resolution.<h3 dir="ltr">Cost</h3>For many years, LiDAR sensors are not an option for most manufacturers thanks to its high cost.A high-end automotive LiDAR by Velodyne used to cost $75,000 for one car.However, in recent years, LiDAR has been undergoing a significant price reduction with many companies working to make LiDAR systems more affordable.In early 2020, Velodyne released <a href="https://velodynelidar.com/press-release/velodyne-lidar-introduces-velabit/" target="_blank">a solid-state LiDAR with no moving parts for $100</a> called Velabit on CES 2020.RADAR systems, on the other hand, have always been a cheaper option compared to LiDAR, with a price as low as $50 for an automotive millimeter-wave RADAR sensor module.The price of LiDAR sensors is partially responsible for the high prices of autonomous vehicles. Most include the use of LiDAR to detect the environment for their self-driving functionality, such as Waymo, Toyota, and Uber, while Tesla continues to avoid LiDAR and <a href="https://electrek.co/2021/01/13/tesla-millimeter-wave-radar-electric-cars/" target="_blank">develop RADAR</a> for its self-driving cars.<h2 dir="ltr">Conclusion</h2>Except for the type of wave used, LiDAR and RADAR are almost identical in principle. Both use a transmitter to emit a wave and use the reflected wave received by the sensor to decide the precise distance to the target.To decide which one is better for your project, you need to decide the requirements and limitations of your measurement unit.LiDAR uses lasers with a much lower wavelength than the radio waves used by RADAR. Thanks to this, LiDAR has better accuracy and precision, which allows it to detect smaller objects, in more detail, and create 3D images based on the high-resolution image it creates.On the other hand, RADAR is much more robust than LiDAR with a lower starting price. While you don&rsquo;t get as many details, it works in worse operating conditions and has a wider range than LiDAR.Alternatively, you can combine RADAR and LiDAR with other sensors using data fusion algorithms to create a system with better capabilities.<h2 dir="ltr">Takeaways&nbsp;</h2>So, here&rsquo;s what you need to remember about LiDAR and RADAR.<ol><li dir="ltr">LiDAR and RADAR are remote sensing devices that use light waves and radio waves respectively to detect objects. They use the interval between the time the waves are transmitted and the time the wave reflected from the object is received.</li><li dir="ltr">Light waves have better precision and accuracy compared to RADAR. However, RADAR sensors are more robust. It performs well in bad weather when LiDAR often fails and has a longer range.</li><li dir="ltr">RADAR systems are more affordable in comparison to LiDAR sensors. However, this might change as many companies continue to develop solid-state LiDARS at a lower price range.</li></ol><hr> <h2 dir="ltr">References&nbsp;</h2>Dong, Pinliang, and Qi Chen. &ldquo;LiDAR Remote Sensing and Applications.&rdquo; 2017, doi:10.4324/9781351233354.Beland, Martin, et al. &ldquo;On Promoting the Use of Lidar Systems in Forest Ecosystem Research.&rdquo;&nbsp;Forest Ecology and Management, vol. 450, 2019, p. 117484., doi:10.1016/j.foreco.2019.117484.Richards, Mark A. Principles of Modern Radar Volume 1: Basic Principles. Scitech Publishing Inc,, 2010.Parker, Michael Alan.&nbsp;Digital Signal Processing 101: Everything You Need to Know to Get Started. Newnes an Imprint of Elsevier, 2017.Ryde, Julian, and Nick Hillier. &ldquo;Performance of Laser and Radar Ranging Devices in Adverse Environmental Conditions.&rdquo;&nbsp;Journal of Field Robotics, vol. 26, no. 9, 2009, pp. 712&ndash;727., doi:10.1002/rob.20310.

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