Techniques, systems, and devices are disclosed for spatial and temporal encoding of transmission in full synthetic transmit aperture imaging to achieve optimal spatial and contrast resolution and large signal-to-noise ratio for medical imaging applications with fewer signal transmissions, which can be equal to or less than the number of array elements within the aperture. In some aspects, a method of signal transmission is disclosed that includes a sequence of one or more sets of transmissions on a plurality of elements with unique, random, and/or optimized combinations of waveforms using amplitude and phase, and/or delay encoding. Sets of echoes corresponding to the sequence are beamformed such that fewer transmissions are needed than the number of array elements within the aperture, while maintaining complete spatial sampling of the aperture as if sampled according to a full set of synthetic transmit aperture transmissions on the same aperture.