PMCW Radar for cars

Started by adaptivefilter 10 months ago5 replieslatest reply 10 months ago455 views


Does anybody working in the automotive radar sector know and can tel me if Phase Modulated Continuous Wave Radar is gaining popularity for mm-wave car radars and how important do they consider ray-tracing simulations for this automotive radar sensors, regardless of the modulation scheme, in the context of moving to ever higher frequencies to obtain better accuracies and reduce antenna size ?

Thank you in advance.

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Reply by jbrowerDecember 14, 2020


My work is in edge computing, specifically where Telcos and hyperscalers meet. I've not been paying attention to technical pros/cons of FMCW vs. PMCW car radar, but I would say that if PMCW gives any long-term advantage for connected vehicle applications, that would be significant.

My understanding is that PMCW enables smaller form-factors, less power consumption, and possibly less complexity for a given performance and interference (radar congestion). If PMCW were to enable more radars on a vehicle, which in turn somehow make it easier to detect radar congestion and/or interface with 5G mm waves, then that could be significant.

Like any engineering challenge, the last few % of corner cases are way more difficult and take years to resolve, and with self-driving cars any corner case where someone gets hurt is a huge deal. Minimizing interference between cars, and sharing data between them will be key to these cases and improving safety and public confidence.


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Reply by fharrisDecember 14, 2020

hello adaptivefilter,

by phase modulated continuous wave radar, I'm assuming you mean linear FM sweep per transmitted pulse. This is the common wave shape for automotive radar because it easy to generate and easy to form the matched filter for returns from different ranges. In the radar community this process is called stretch. Building models of multiple reflectors of different radar cross sections distributed over different ranges and cross range angles along with ground returns is important for simulations. I don't think that ray tracing does justice to the large range of Doppler shifts due to moving reflectors and non moving reflectors in the field of view as well as the time varying environment and the near far problem in signal strength. Nor does the ray tracing accommodate jamming signals from many of the platforms also illuminating the same environment with 1/R^2 signal strength as opposed to 1/R^4 return signal strength. 

Higher operating frequencies permit easier beam forming options but also suffer from channel loss, particularly water and mud from rain, splash, and wheel borne spray.          

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Reply by Mannai_MuraliDecember 15, 2020

Phase Modulated Continuous Wave (PMCW) radar is different from Linear FMCW radar.It has PN sequences (+1/-1) generated modulated BPSK and transmitted.By cross correlating with reference we can find the range.PMCW is better than LMCW radar and the latest.If you went more details please mail me.

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Reply by fharrisDecember 16, 2020
Hi mannai,

Thanks for pointing out that I misinterpreted the DSP radar question. 

I am quite familiar with direct sequence spreading sequence radars. I worked for a two year stint during an extended sabbatical from the university at Hughes Aircraft in El Segundo. I worked on the digital radars which included the high resolution imaging radars on the B2 aircraft. If you have not seen the book RF Stealth by David Lynch, you should chase down a copy (amazon has it). I worked with Dave Lynch, a very capable person! I still do some radar work with the Raytheon group that acquired the radar segment of Hughes when GM sold it off.  

I also spent some time working with Uhnder, in Austin, on their DSSS automotive radar. Very impressive with a multiple phased array beamforming system.

If you have any interesting material you can share with me I would welcome it. I would share it with my students, two of which are doing projects on collision avoidance radars.

Best regards

stay safe and stay well

fred h

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Reply by NirRegevDecember 17, 2020

Yes - it is gaining traction in the autonomous vehicle industry, as it has some pros over a FMCW radar. Ray tracing also plays a major role in simulation and emulations.

Hope this helps