BK Medical bkSpecto 1300, Руководство по обслуживанию

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bkSpecto Ultrasound System Theory of Operation
SM41406-4 8-5
The front-end part is responsible for providing the physical interface to ultrasound
transducers, generating high-voltage pulses to excite the transducer ceramics, and
amplifying and acquiring the low-voltage echoes from the transducers. Figure 8-3 is an
overview of the main block on the front end.
Transmit Beamformer Function
Supplying the Transmitter and T/R Function with 64 individual transmit waveforms with
individual delays in order to focus the emission in a specific direction and distance.
Emissions may also be unfocused. The Transmit Beamformer Function consists of a FPGA
and a local memory for Tx Delay Profiles. These profiles are calculated by the CPU on the
COM Express Type-6 Module and transferred to the local memory.
Apart from generating transmit profiles, the Transmit Beamformer Function also controls the
HV Multiplexers and handles real-time signals to/from the probe connectors in the Probe
Mux and SPP Function.
Transmitter and T/R Function
The transmit pulsers are responsible for converting the drive control signals from the
Transmit Beamformer Function into high-voltage pulses that excite the transducer arrays,
thus generating a sound field in the tissue.
The T/R switches are responsible for protecting the sensitive small-signal amplifiers in the
Receiver Function from the high-voltage signals from the pulsers and for removing the load
(represented by the pulsers outputs) on the element wires during receive.
Probe Mux and SPP Function
Connecting up to 192 probe elements to the 64 electrical channels (1:3 mux/demux) and
providing the four physical transducer connectors. The probe mux can be seen not only as a
1-of-4 selector, but more generally as a 64-to-768 mux. It is therefore possible to scan
simultaneously on two or more connectors.
The Smart Probe Port (SPP) comprises a controller which takes care of virtualizing the
hardware probe interfaces. This controller communicates directly with the CPU on the COM
Express Type-6 Module via a USB link.
The Probe Mux and SPP Function
further provides power switches to apply power to any
active probe. Probe power is used for control logic, for motor drivers, and for built-in HV
multiplexers. It also provides monitoring circuits to detect high-voltage leakage to the
connector pins (hazard).
Receiver Function
Amplifying each of the low-voltage outputs, caused by ultrasound echoes, from the
transducers and converting the analog signals to digital form. The signal path is shown
above. The VGA amplification is time-variant and is controlled by the ATGC Function. This
control is common to all channels. The Receiver Function includes analog filters for
optimizing the signal in the frequency range of interest at the input of the A/D converters.
In CW mode, the Receiver Function does not use the VGA, PGA and ADC stages. Instead,
the outputs from the LNA are mixed with a phase adjusted clock, forming complex (I/Q),
baseband signals to the CW Function. The Receiver Function receives its sampling and
mixer clocks from the ClkGen Function.
Receive Beamformer Function