Frequency Modulated Continuous Wave Technologies


Basically, CW radar doesn’t calculate the distance or measure range of the target- this is one of its primary limitations. And that’s where Frequency Modulated Continuous Wave radar and LiDAR come in. FMCW radar and FMCW LiDar technologies serve the same purpose. Their purpose is to sense and calculate an object’s range and radial velocity. However, there is a difference between the two. For example, the RADAR systems use radio waves while FMCW LiDar use LED light.

In the Frequency Modulated Continuous Wave Radar, the transmitter’s recurrence rate is constantly varied at a standard rate. Also, the radar receiver receives reflected frequency signal and compares it with transmitted frequency.  The receiver and the transmitter make up the Radar.

The Characteristics of FMCW Radar

Below are the traits of FMCW radar;

  • Can measure small ranges to the object
  • Can measure the target range plus its relative velocity at the same time
  • Its range of measurement is accurate
  • After mixing, signal processing is usually carried out at a low-frequency range, thereby streamlining      processing circuits realization.

Measurement Principle

You get the distance measurement by equating the received signal frequency to a reference

The transmitted waveform (T) time length is longer than the expected receiving duration for the installed distance calculation range.

Basically, a radar signal is released through an antenna on the object’s surface and attained after a time (t). In this case, FMCW is used as the radar principle. Frequency Modulated Continuous Wave radar carries a high-frequency signal- the signal’s frequency rises linearly in the course of measurement, commonly referred to as frequency sweep.

The signal released and revealed from the measuring point and attained a time delay, t. In other words, Delay time = 2d/c. D refers to the distance to the object’s surface, while c is the speediness of the gaslight above the object.

In addition, signal processing further involves calculating the frequency difference, generally calculated from the receive frequency and the actual frequency. Large frequency difference relates to a wider distance.

Δf or frequency difference is converted through an FFT (Fourier transformation) to a frequency spectrum. The distance is then calculated from the frequency spectrum. The difference between the measuring distance and the tank height leads to the level.

The frequency difference that’s processed by FFT (Fast Fourier Transformation) to detect the Intermedium Frequency (IF) signal. The FMCW radar is inherent and has signal enhancement and echo-back filtering through PLL (Phase-Lock Loop) circuit- an excellent solution for high accuracy measurement and complex environment.

Benefits of FMCW Radar

Below are the advantages of FMCW radar technology;

  • Frequency Modulated Continuous Wave Radar is referred to as an altimeter. It’s mainly used in aircraft to take height measurements.
  • It uses low power for transmission purposes, which can be supplied by most solid-state devices, including BWO, magnetron, and reflex klystron.
  • It provides a broader bandwidth, unlike the CW radar
  • It delivers exceptional stability and sensitivity thanks to the super-heterodyne-based architecture.

Finally, the primary Frequency Modulated Continuous Wave radar benefit is resistance to interception, solid-state transmitters, not to mention the good range resolution. FMCW technologies carry out the range and velocity measurement. Also, it’s an excellent solution for noncontact vital signs identification.

Zayd Dana
the authorZayd Dana