by Rainer Makowitz
RADAR has been quickly adopted as the foundation of the new Advanced Driver Assistance Systems (ADAS) that are being introduced by vehicle manufacturers around the globe.
The RADAR technology has several benefits over other forward-facing sensor technologies, like cameras. It can operate under adverse weather conditions, can ‘see through’ objects to detect smaller targets and is the primary method to determine speed of objects around the car. What was used in police cruisers to provide hard evidence against speed limit offenders has now come to be used as a preventive means to make driving safer.
The choice of 76-81 GHz as the operating frequency band was made by a standards organization to obtain exceptional resolution and also to have a globally agreed frequency band exclusively for this application.
At the Freescale Technology Forum (20-24 June, 2011) in San Antonio, Astyx and Freescale demonstrated a high resolution 77GHz RADAR sensor that is designed to be used in the next generation of automotive ADAS systems. New technological advancements over conventional automotive RADAR systems include:
- Digital beam forming using multiple receive channels
- Full 2D object detection
- High resolution in space and velocity
- Highly integrated RF components
Digital beam forming requires many receiver channels, which made it costly and complex to implement in the past. This demo has implemented unprecedented 16 receiver channels integrated into four Freescale BiCMOS receiver chips driving high-resolution imaging. The high dynamics requirements of automotive use case require fast frequency sweep in the transmitter. The Freescale transmitter implementation represents the market leading trade-off between frequency stability and fast sweep operation.
The flexible Digital Beam Forming RADAR sensor architecture designed by Astyx allows several sensor ‘personalities’ (short range – up to 50m, or long range – 250m) to be defined by software options only.
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