Technical and Design Glossary
mmWaves
mmWaves refers to electromagnetic waves with wavelengths between 1 mm and 10 mm (or frequency ranges from approximately 30 GHz to 300 GHz). They are radio waves in a high-frequency band, and mmWave radars utilize this frequency band for high-precision distance and speed detection. Due to their resistance to obstacles, they can provide stable detection even in foggy or smoky environments.
Frequency band
The frequency band indicates the number of vibrations of radio waves (frequency range), and the unit of measurement is Hertz (Hz). mmWave radars primarily use a high-frequency band between 30 GHz and 300 GHz, which enables high-precision distance measurement and high-speed detection.
Wavelength
The wavelength of a radio wave represents one cycle length, and it is inversely related to the frequency. Shorter wavelengths correspond to higher frequencies. mmWaves have extremely short wavelengths, which makes them suited to detecting minute objects and performing high-precision measurements.
Reflected waves
Reflected waves are radio waves that bounce back when incident mmWaves hit an object (boundary surface). Radar analyzes the arrival time and frequency changes of these reflected waves to measure the distance to the target and speed.
Doppler effect
The Doppler effect is a phenomenon wherein the frequency of the waves changes due to the movement or displacement of the wave source or observer. This effect is used in mmWave radar to measure the speed of the target, and it is useful for detecting the speed and direction of moving objects.
SNR (Signal-to-Noise Ratio)
SNR stands for Signal-to-Noise Ratio, and it represents the ratio of the signal strength to the noise strength. A high SNR indicates a clear signal against the noise, which is essential for high-precision detection and analysis.
Beam width
The beam width in communication technology refers to the range of angles through which a radar’s transmitting or receiving antenna emits or detects radio waves. A narrow beam width indicates a high directivity and resolution, which allows for more precise target detection.
Pulse compression
Pulse compression is a technique that uses temporally long pulses with respect to the transmitted radar signal and compresses the signal during reception to achieve high distance resolution. This technique makes high-precision measurement possible even at great distances.
Phased array
A phased array is a technology that controls the beam of radio waves emitted or received by multiple antenna elements to electronically adjust the direction of the radio waves. It can quickly change the direction of the beam without mechanical movement, which makes it effective for tracking and multi-directional detection.
FFT
FFT stands for Fast Fourier Transform, which is an algorithm used to convert time-domain signals into frequency-domain signals. FFT enables high-speed processing of large data sets and is used in analyzing signals received by mmWave radar. FFT is an essential processing technology for accurately detecting the speed and distance of a target.
Sample rate
The sample rate is the sampling frequency when digitizing an analog signal. The unit of measurement is Hz (samples per second). A higher sample rate enables more detailed signal analysis.
Throughput
The throughput represents the amount of data that a system can process within a fixed time. Since mmWave radar processes vast amounts of data in real-time, it requires a system design with a high throughput.
Sensitivity in measurement engineering
The sensitivity refers to a sensor’s ability to detect minute signals. High sensitivity mmWave radars can detect objects at great distances or at small sizes.
Resolution
Resolution is an indicator that refers to how finely radars can distinguish target positions or speeds. Examples include distance resolution and speed resolution, with high resolution achieving high-precision testing and tracking.
Certification (FCC, CE, etc.)
Certification is a procedure for certifying that a product complies with the radio wave regulations and safety standards in each country. Obtaining certifications from bodies such as the FCC (US) or CE (EU) is essential for sales and usage in the global market.
FMCW method (Frequency-Modulated Continuous Wave)
The FMCW (Frequency Modulated Continuous Wave) method transmits radio waves with continuously changing frequencies over time and analyzes the frequency difference (beat frequency) with the reflected waves to simultaneously measure the speed and distance to the target. This method offers both a high distance resolution and speed resolution and is being adopted in mmWave sensor modules used in a wide range of fields such as industrial equipment and smart home devices, etc.
Doppler method
The Doppler method transmits a continuous wave at a constant frequency and detects the frequency change (Doppler shift) of the reflected waves that bounce back from the moving object to measure the object’s speed. The structure is comparatively simple and suited to applications specializing in speed detection. However, because it is not suited to distance measurement, it is often used in combination with other methods.
Pulse method
The pulse method transmits extremely short radio wave pulses (short-duration high-frequency signals) and measures the time it takes for the reflected waves to return after hitting the target (round-trip time) to calculate the distance. The simple principle behind this method allows it to achieve a high distance resolution that is used in long-distance applications such as aviation and weather radar, etc. However, its use in mmWave radar is limited due to precision and cost issues with the pulse generation circuit and the reception circuit.