Gradient System: Gradient Array Controller

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Gradient System · Digital Design

Turning a pulse sequence into a waveform for every element of the array, in real time.

Block diagram of the gradient array controller
The controller maps the requested encoding field onto every channel, in real time.

The question

With three fixed axes, gradient control is three waveforms. With an array, the sequence still asks for an encoding field, but the controller has to map that request onto every element, and the mapping depends on the region over which linearity was requested. The waveform per element is therefore computed rather than stored, and it has to be ready on time, every time.

The architecture

  • The controller takes the pulse sequence, generates the time-domain gradient waveforms, maps them onto the array channels, and drives the amplifiers.
  • It shares the platform and conventions of the receiver and transmitter projects, and the same spectrometer acts as the sequence engine for all three.