Help: ICE_GENERAL_FTT
Fast Tuner Transform Concept of Operation
The DTDM/DTDMX Modules have 64Mby of DRAM and a fast memory crossbar that allows
multiple reuse of the 8 graychips. The FTT is a multipass algorithm similar to
a radix-16 FFT pass. A first Bank of 16 tuners selects 1-16 blocks of the input
spectrum and streams them to circular buffers in memory. The second bank of 16
tuners then selects 1-16 blocks from each of these streams (much faster than
real-time) and streams them back to memory. This is practical for 2 to 3 passes.
The FTT algorithm is enabled by adding the FTTM=2 or FTTM=3 flag in the device
configuration stream and accessing a Tuner Bank. By default, the pic_ioport call
will implement as many channels as possible given the port, decimation, channel
spacing, and number of FTT passes (specified by FFTM=N). To use less channels,
set KEY_CHNS=n before the call to pic_ioport().
For more details, see the help on the FTTM flag.