FujiFilm SonoSite EDGE II Service Manual page 37

focal point at the same time. The number of elements driven is determined by element sensitivity off axis
and depth of field considerations. The waveform is selected to drive the transducer at a certain center
frequency, bandwidth, and power and is optimized for the given mode.
The receive section consists of a transmit/receive switch to protect the receiver from the transmit voltage, a
variable gain receiver to amplify and condition the return echoes, an A/D to digitize the data, a delay block
to focus the return signals and a weight block to scale the return echoes for each channel. All the signals
are then summed together to generate the beam-formed receive data. The analog gain varies with depth
to compensate for signal attenuation through the medium. The delays and weights are independent for
each channel. The delay and weight for the receive channel can typically be changed dynamically to keep
the receive beam in continuous focus. The delay is simply set by the time of flight in the medium from the
point of interest to the element, which starts at skin-line and proceeds to the deepest depth of interest.
The control section drives the data to the various data path elements on a line by line basis, controls the
timing of the transmit and receive sections and controls the tagged information and timing of the data to the
rest of the system.
Chapter 4: System Overview 29