To provide context, a 10us FMCW pulse spreads light radially across 1.5km range. While there will be nice videos of FMCW and other low TRL systems in well controlled environments with expensive prototypes, it’s a whole different world when taking harsh environments and mass production into account. Again, in the case of lateral velocity, no FMCW system will instantly detect lateral speed at all without multi-position estimates such as those used by TOF systems, but with the additional baggage of long FMCW dwell times.Lastly, in an extreme TOF example, the AEye system has demonstrated detected objects at 1km. With an agile scanner, such as the one AEye has developed, the 500us is not solely dedicated or “captive” to velocity estimation.

Multi-echo processing is especially important in dealing with obscurants like smoke, steam, and fog.FMCW purports to be advantaged by the fact that it leverages photonics and telecommunications technology maturity, thereby facilitating scalability to higher performance levels (in addition to cost savings). The result can also be a significant reduction of usable dynamic range. These might use a single scanning MEMS, but each replicated item is most of the cost of the LiDAR system, so doubling channels nearly doubles the overall cost of the LiDAR.In FMCW systems, coherence length is determined by how the laser is designed and fabricated and must be at least twice as long as the longest target range. It’s simple. It is well known that phased array beam steering degrades (creates spatial sidelobes) very quickly with frequency shifts of the laser beam. Indeed, virtually Consider a car moving between 30 and 40 meters/second (~67 to 89 MPH) detected by a laser shot. We can use the time wisely to look at other areas/targets before returning to the original target for a high confidence velocity measurement. The 1Of course, deeper sidelobe taper can be applied, but at the sacrifice of pulse broadening. These specific types of components are very low risk from a supply base point-of-view. Aeva FMCW Lidar Two veterans of the yet-to-be-taken-public, Apple driverless car project have left the mother-ship and gone off on their own to form Aeva. Any objects within this range extent will be caught in the FFT (time) sidelobes. Whereas, it requires significant disambiguation in FMCW systems. Two veterans of the yet-to-be-taken-public, Apple driverless car project have left the mother-ship and gone off on their own to form Aeva. This is a significant gap in technology readiness and will take many years to close. The same thing is happening with the cost and capability of lidar sensors and technology.

The bandwidth of the electronics is proportional to the range resolution and for common LiDAR system requirements, the components are nothing unusual.FMCW requires ADC conversion rates that are two- to four-times as high as a TOF system and then must be followed by an FPGA capable of taking the data in and doing very high speed FFT conversions. We believe this path can take another 10 years to reach usable maturity.AEye believes that high shot-rate, agile-scanning TOF systems serve the needs of autonomous vehicle LiDAR more effectively than FMCW when cost, range, performance, and point cloud quality are important. let’s be sure we have a basic understanding of FMCW since that may be something you can actually make use of in the future. I have not even seen this topic mentioned by the ToF’ers.Seems like that is a major advantage, along with the ability to not be affected by glare and potentially the biggest item of all, the ability to measure the velocity of moving objects in the path of the vehicle.I am not convinced that the ability to measure velocity is a must-have, but as long as the software can make efficient use of the information I would probably say why not. Below is a summary of our views and a side-by-side comparison between TOF vs. FMCW LiDAR claims.Contrary to the recent news articles, FMCW LiDAR has been around for a very long time, with its beginnings stemming from work done at MIT Lincoln Laboratory in the 1960s,TOF LiDAR systems can offer very fast laser shot rates (several million shots per second in the AEye system), agile scanning, increased return salience, and the ability to apply high density Regions of Interest (ROIs)—giving you a factor of 2x–4x better information from returns versus other systems. By comparison, the critical component for FMCW systems is the very low phase noise laser, which has many tight requirements and no other high-volume user to help drive down volume manufacturing costs. Furthermore, windshields, being multilayer glass under mechanical stress, have complex inhomogeneous polarization. No amount of dynamic range between small and large offset returns has any effect on the light incident on the photodetector when the small target return is captured. Even here though, a coaxial FMCW system and a coaxial TOF system will not see significant differences in detector costs based on detector sizes needed.