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.