Help: ICE_FLAGS_FTTM=N
Fast Tuner Transform Mode controls various bank of tuners algorithms.
Fast Tuner Transform Mode controls various bank of tuners algorithms.
FTTM<0 Individual tuner decimation, freq, dma channels (max 16 chan/side)
FTTM=0 Shared dma channel, same decimation, independent freq (16 chan/side)
FTTM=1 Shared dma channel, same decimation, set freq spacing (16 chan/side)
FTTM=2 Shared dma channel, same decimation, set freq spacing, A/B locked, (128 chan/side)
FTTM=3 Shared dma channel, same decimation, set freq spacing, A/B locked, (2048 chan/side)
By default, the tuners have FTT turned off, FTTM<0. On the DTDM processor modules,
the FTT algorithm allows the graychips to produce more channels than the traditional
straight through approach. The algorithm uses half of the graychips to select blocks
of the spectrum from the wideband input and write them to memory. The other graychips
are used to further process these streams into individual channels.
The algorithm will attempt to determine the following operational parameters on its own,
but you can override these by specifying the following flags:
FTTD1=n Initial up front decimation
FTTN1=n Initial up front channels
FTTD2=n Stage 2 decimation
FTTN2=n Stage 2 channels
FTTD3=n Stage 3 decimation
FTTN3=n Stage 3 channels
The resampler can only be used if the ratio can be expressed as (P/X)*D2 where both P and
X are a multiple of 64 bytes. X is the transfer length into the stage 2 tuners <= 512K.
P is the stage 2 tuner production length <= 64K. The graychips do not support setting the
resampler phase, so it must start and end each pass at phase=0.
FTTX2=n Stage 2 transfer length
FTTP2=n Stage 2 produce length
The front end tuner gains are set by the standard gain parameter. To set the gain in the
2nd and 3rd stage, use:
FTTG2=n Stage 2+ gain
The number of usable channels depends on the FTTM mode, decimation, and channel spacing.
The CHNS=n flag can be used to limit the number of channels output to less than the
default of N1*N2*N3.
There are a number of restrictions. Apply the VERBOSE flag to see the actual parameters used.
Resampling is applied to the last stage only.