BACKGROUND

An automotive radar system collects information about the speed and distance of stationary and moving targets (e.g., other vehicles, pedestrians, obstacles, other objects of interest) located outside an automobile. With multiple transceivers and an ability to transmit and process more independent and distinct signals simultaneously, a multiple-input multiple-output (MIMO) radar system can collect large amounts of radar information quickly, which is suited for collision avoidance and other active safety or autonomous-driving features of the automobile. Unfortunately, MIMO radar systems are typically greater in size and cost due to their increased complexity.

Cascade radar systems are forms of MIMO radar systems that minimize complexity (and therefore size and cost) by operating all the transceivers according to a primary local oscillator (LO) signal. The primary LO signal is used for both up-conversions and down-conversions in the transceiver. If the primary LO signal is a modulated signal, it is also used to modulate the radar transmit signal and demodulate the radar receive signal. Only one transceiver is designated a “primary” transceiver making that transceiver responsible for generating the primary LO signal and for itself and all other “secondary” transceivers. The chirp length and bandwidth of the cascaded radar system are limited by constraints (e.g., settling time, resetting time) associated with the primary LO signal, causing an undesirable delay between the end of a current chirp and the start of a next chirp.

SUMMARY

The techniques of this disclosure enable scalable cascading radar systems (e.g., for automotive applications) that are not limited by constraints (e.g., settling time and resetting time) of a single LO signal used in a traditional cascading radar system. Instead, an example scalable cascading radar system is described that combines multiple LO signals output from at least some of the multiple transceivers of the radar system and distributes a common oscillator signal derived from the combination of LO signals as the LO signal input to all of the transceivers of the radar system. This common oscillator signal reduces settling time and resetting time of a traditional LO signal in a cascaded radar system, and therefore enables consecutive chirps to occur more frequently. The common oscillator signal, having been created from a combination of LO signals of multiple transceivers, addresses the settling time and resetting time issues that prevent fast-chirp waveforms when only a single primary transceiver is used. The common oscillator signals enable the generation of additional chirp waveforms with different characteristics, such as center frequency and bandwidth, to improve range resolution and Doppler coverage. Different waveforms enable the cascading radar system to achieve waveform diversity, making the cascading radar system more versatile and able to detect additional types of targets that otherwise go undetected unless particular waveforms are used. The common oscillator signal of the example cascading radar system further enables better orthogonality among transmit (TX) channels and more robust protection from interference.

In some aspects, a scalable cascading automotive radar system is described including: a plurality of transceivers including a first transceiver and a second transceiver each configured to output a respective local oscillator (LO) signal; a combiner configured to merge the respective LO signal that is output from the first transceiver with the respective LO signal that is output from the second transceiver into a common oscillator signal; a divider configured to distribute the common oscillator signal to each of the plurality of transceivers when the transceivers are emitting radar signals for detecting radar reflections from targets outside an automobile; and a radar control component configured to output information associated with the radar reflections detected from the radar signals that reached the targets outside the automobile.

In other aspects, a scalable cascading automotive radar system is described including: a plurality of transceivers each capable of outputting a respective local oscillator (LO) signal; a combiner configured to merge the respective LO signal that is output from at least two of the plurality of transceivers into a common oscillator signal; a divider configured to distribute the common oscillator signal to each of the plurality of transceivers when the transceivers are emitting radar signals for detecting radar reflections from targets outside an automobile; and a radar control component configured to output information about the radar reflections that reached the targets outside the automobile.

In additional aspects, a method includes obtaining, from each of at least two transceivers of a scalable cascading automotive radar system, a respective local oscillator (LO) signal; generating, based on a combination of the respective LO signals output from the at least two transceivers, a common oscillator signal for input to the at least two transceivers when the at least two transceivers are emitting radar signals for detecting radar reflections from targets outside an automobile; and inputting the common oscillator signal into a respective LO signal input of each of the at least two transceivers when the at least two transceivers are emitting the radar signals for detecting the radar reflections from the targets outside the automobile.

This document also describes computer-readable media having instructions for performing the above-summarized method. Other methods are set forth herein, as well as systems and means for performing the above-summarized and these other methods. This summary is provided to introduce simplified concepts for scalable cascading automotive radar systems, which is further described below in the Detailed Description and Drawings. For ease of description, the disclosure focuses on automotive radar systems; however, the techniques are not limited to automobiles, but apply to radars of other types of vehicles and systems. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining the scope of the claimed subject matter.

