Fig. 1. Scheme diagram of the proposed approach.

Fig. 2. Frequency-time two-dimensional (2D) image to illustrate the intrinsic feature of an LFM signal, and the dual-frequency generation using AMZI for concurrent measurement of TDOA and chirp rate.

Fig. 3. Diagram of the whole measurement system.

Fig. 4. Waveform and spectrum of the measured signal at different SNRs. (a) Waveform with SNR=9.6dB shows the beating of two sinusoidal signals; (b) spectrum with SNR=9.6dB shows two frequency peaks; (c) waveform with SNR=−10.4dB shows nothing but noise in the retrieved signal; (d) spectrum with SNR=−10.4dB is still able to reveal two frequency components.

Fig. 5. Measured chirp rate versus SNR.

Fig. 6. Measured two-tone spectrum at different time delays.

Fig. 7. AOA measurement results and their measurement error at different SNRs. (a) AOA measurement results and (b) measurement error with SNR=9.6dB. (c) AOA measurement results and (b) measurement error with SNR=−10.4dB.