A Modified LFM Signal in Coded Ultrasound

The linear nature of linear frequency modulation (LFM) waveform makes it rather insensitive to frequency shifts, a property which is of great importance in ultrasound imaging. However, relatively high sidelobes remain in the autocorrelation function (ACF). A modified FLM waveform is proposed by combining LFM with binary frequency code. This waveform maintains the linear nature of LFM and at same time low sidelobos are exhibited. Simulated results show the relation between the sidelobes reduction with the amplitude of the binary frequency code.