On Hardware Implementations of Stepped-Carrier OFDM Radars

Orthogonal frequency-division multiplexing (OFDM) is a promising candidate for future digital-centric radar systems. One major limitation for practical implementations is the required sampling rate in the order of GHz, which can be solved by using a stepped-carrier technique in combination with OFDM signals of smaller bandwidth, theoretically resulting in the same resolution as a conventional OFDM scheme. However, a signal source capable of generating such a carrier has to fulfill several constraints. In this paper, the effects of deterministic and random inaccuracies of the carrier generation as well as effects of phase noise are described and evaluated. A transient model that describes the switching between carriers is given and all effects are verified using a radar demonstrator at 77 GHz.