Envelope Sampling

The envelope sampling is the start of the back-end process. Normally the beamformed signals are converted to real (I) and quadrature(Q) components. These two components can then be combined to obtain the envelope of the signal. This step is followed by amplifiers (TGCs) that can be controlled by the user to operate linearly at one extreme, or as a logarithmic amplifier at the other extreme, or between. For wide-band systems, this approach will introduces a lot of errors when generate the envelope. New approaches have been developed to reduce the errors and achieve higher resolutions.