What Is Radar? Radio Detection and Ranging is a system or device that uses electromagnetic radio waves to determine the range, velocity, and angle of the objects in the surrounding area. This system transmits an electromagnetic wave signal, which is reflected by an object in the path. By capturing this reflected signal and with some signal processing, RADAR systems can determine the range, velocity, and angle of the interested objects. These attributes of RADAR treat them as sensors, often called RADAR sensors.
A complete RADAR system comprises a transmitter (TX) and receiver (RX) of radio frequency (RF) components; analog components for clocking; and digital components such as Analog to Digital Converters (ADCs), microcontrollers (MCUs) and Digital Signal Processors. Even after having such usability, RADAR did not find application in any domain other than weather, remote sensing, and satellites. The major reason for this being the need to design a high-precision RADAR with low cost and low power consumption. The latest improvement in semiconductor technology has led the RADAR’s discrete components to be more cost and power effective with improved precision and configurability. The use of a short wavelength like the millimeter wave from the electromagnetic spectrum in the RADAR gives advantages of smaller antennae and other device form factors, which often integrate the whole RADAR system in a chip. This advancement has spurred applications, research, and developments in wireless sensing and finding engineering solutions for different domains using mmWave RADAR sensors.
Besides RADAR, there are many remote or wireless sensing options such as camera, Light Detection and Ranging (LiDAR), and ultrasonics, but these sensors have operational range limitation, environmental limitation, and some of them are expensive. RADAR can offer better solutions to them. Also, various privacy laws restricting the use of common sensors like cameras. However, RADAR lacks object classification and has sparse detection. The advent of Machine Learning (ML) and Artificial Intelligence (AI) with new estimation techniques and the concept of Multiple-Input Multiple-Output (MIMO) has improved RADAR application greatly to act as a standalone sensor or complement fusion sensor. restrict uses of common sensors like cameras. On the other hand, RADAR lacks object classification and has relatively sparse detection. The advent of Machine Learning (ML) and Artificial Intelligence (AI) with new estimation techniques and the concept of Multiple-Input Multiple-Output has improved RADAR application greatly to act as a standalone sensor or complement fusion sensors.
With the market development, the scope of application of the mmWave RADAR has expanded beyond the automotive field, gradually to smart cities, building automation, health monitoring, and other industries. Market and Markets’ Recently released data shows by 2023, the total market in millimeter pod sensors will reach $20.6 billion. Car RADAR is the main driving force of this wave of growth, but with the Internet of Things (IoT), the healthcare market is expected to become another wheel that drives the millimeter wave RADAR market.
Applications:
- Automative Applications: 4D mmWave RADAR for multi-object tracking device in advanced driving assistant systems (ADAS), for driving safety, collision detection, and parking aids.
- mmWave RADAR can detect and monitor human gestures, emotions, movements, blood circulation, and heartbeat along with offering some privacy.
- Robotics Applications: Used for imaging and sensing, object detection, navigation, and vision.
- Meteorological Applications: mmWave RADAR helps in cloud analysis, crop analysis, radiometry, GIS, and climate study.
- Aerospace and defenseMissile interception and guidance, UAV, airborne ranging, stealth operations, and flight controls.
- Industrial and Automation ApplicationFor quality control, crack detection, liquid and volumetric flow detection, leakages, and material classification.
- Civilian applicationsUsed in air traffic control systems, low-altitude space surveillance, risk avoidance early warning system, surveillance in debris area or snowy area, smart city, IoT, and intelligent home.
In the following section, we will review and understand the technical aspects, application aspects, some mmWave RADAR concepts, estimation techniques, and MIMO concept. We will also look at different implementation platforms for RADAR estimation DSP part.
mmWave RADAR is a non-contact sensor, working in a spectrum of 10 millimeters (30 GHz) to 1 millimeter (300 GHz). This offers accurate location sensing, velocity, and angle, and can be performed with no interference. mmWave RADAR transmits pulse signals and detects targets from the reflections it receives through an array of antennas. Further processing estimates the distance to the target, angle of arrival, and the relative velocity. Currently, there are three major working bands – 24GHz millimeters, 77GHz millimeter, and 60GHz millimeter wave RADAR. 24GHz millimeter wave RADAR is cheap but has lesser bandwidth (250MHz) limiting application and accuracy. The 77GHz band has a high bandwidth of 4GHz, gives higher resolution/accuracy thus picking up for 24Ghz band. The 60GHz mm RADAR with 7GHz bandwidth used for short-range applications with high precision also offers a smaller system design. The 60GHz band is expected to become the mainstream of the intelligent homes market and health monitoring.
Advantages of millimeter wave RADAR:
- Small antenna caliber: Narrow beam gives high tracking, accuracy; high-level resolution, high-resistance interference performance of narrow beam; high antenna gain; smaller object detection.
- Large bandwidth: High information rate, details structural features of the target; reduces multipath, and enhances anti-interference ability; overcomes mutual interference; high-distance resolution.
- High Doppler frequency: Good detection and recognition ability of slow objectives and vibration targets; can work in snow conditions.
- Good anti-blanking performance: Works on the most used stealth material.
- Robustness to atmospheric conditions such as dust, smoke, and fog compared to other sensors.
- Operation under different lights: RADAR can operate under bright lights, dazzling lights, or no lights.
- Insusceptible to ground clutter: Allowing for close-range observations. The low reflectivity can be measured using mmWave RADAR.
- Fine spatial resolution for the same range, mmWave RADAR offers finer spatial resolution than microwave RADAR.
Limitations of millimeter wave RADAR:
- Line of sight operation.
- Affected by water content, gases in environment.
- Affected by contaminated environment and physical obstacles.
By Snehal Buche, eInfochips
From design-reuse