2pSENSE - Model FMCW -Radar Sensors

This underlying principle of operation is called homodyne detection and forms the backbone of FMCW radar systems. The signal resulting from this frequency conversion is often referred to as the intermediate frequency (or IF) signal and is the key to extracting information about the measurement. See it for yourself in this animation.

Using basic geometry knowledge, we can see that the frequency of the IF signal is directly linear to the time the electromagnetic wave takes travelling from the radar to the target and back (often referred to as Time-of-Flight). Finally, assuming the electromagnetic wave velocity is known (and constant), we can easily derive the distance to the target from the actual frequency.

Bandwidth is Everything
FMCW radar systems have one unique trick up their sleeves — By linear superposition, they can perform ranging and detection on multiple targets simultaneously, as long as the targets are separated from each other by a distance often referred to as the range resolution. And range resolution is inversely proportional and directly dependent on the system bandwidth.

Higher Bandwidth — Better Resolution.

 is the first D-band FMCW radar technology both in Academia and on the market achieving a record bandwidth of 56 GHz resulting in a range resolution of approximately 2.5 millimeters. This bandwidth is achieved at a very high signal quality, owing to an offset-PLL generation scheme [1].

Exceptionally stable: Accuracy & Precision //

Certainty of Measurement
The  technology is able to achieve both impressive accuracy and precision. Accuracy describes how close a measured value is to its true value while precision is mostly a matter of how stable the measured value is over time, temperature, or other factors.

With typical FMCW radar systems, their accuracy and stability is foremost dependent on the accuracy and stability of the reference clock. Many commercial radar systems use regular or temperature-compensated crystal oscillators as reference clocks resulting in +/-25 ppm up to +/-5 ppm of stability (excluding aging) with their absolute frequency tolerance being an additional +/- 10 to +/- 25 ppm.

// Exceptionally stable: Reference Clock //

Achieving Micro­meter Accuracy
In a typical ranging application one ppm frequency error is equal to 0.5µm/m measurement error due to the time-of-flight distance being twice the range. Thus for achieving a 1µm/m measurement accuracy, the total reference clock frequency error has to be less than 2 ppm. This includes absolute frequency tolerance as well as the stability of the clock source.

2π-LABS has invested an enormous amount of energy in improving both the achievable accuracy as well as precision in the  technology, while maintaining low signal noise. This is accomplished using a patented multi-loop frequency stabilization scheme [7], where the reference oscillator itself can be locked to an external clock source or to an optional internal highly accurate, stable and digitally tunable MEMS oscillator, achieving measurement equipment-grade stability. [8]