The MC4C40 is a generic processor board with four C40 DSPs from Texas Instruments. Each DSP is supplied with 128kByte of memory and provided with links to all other DSPs and a RS485 interface for out-going signals to the TX_Module. The gradient pulse amplitudes are supplied over the GCTX board described below.
The DSPs are named according to their functions as follows:
- DSP1 for transmit amplitudes (TX)
- DSP2 for gradient amplitudes (GC)
- DSP3 for SAR calculation and image header (RX)
- DSP4 for eddy current compensation (ECC)
The GCTX is a specially designed board realized as a piggy back (it plugs on top of the MC4C40 board) containing all the functional circuitry for the sequence RF pulse generation, the data delay circuits and synchronization pipeline for the gradient pulses and the TICO section which is responsible for providing the timing for the
The main tasks are:
- The TICO generates the sequence timing for Grad, RF-TX (incl. PFPA_UNBL) and RF-RX. Also the control signals for the RF coil dynamic detuning are generated here. They are sent to the RFCI via the backplane.
- The Grad unit synchronizes the prepared Grad amplitude (from DSP2/4) with the delay generator.
- The RF-TX performs the digital modulation with the MOFI chip.
- The NCO provides the carrier (Local Oscillator) for the
- TX_IF signal (slice position) and demodulation on the RX4 (RXLO_xx)