CRC-DabMod usage

Usage:

	CRC-DabMod [input [output]] [-c clockrate] [-f] [-g gainMode] [-h] [-r samplingRate]

Where:

input:    ETI input filename (default: stdin).
output:   COFDM output filename (default: stdout).
-c:       Set the DAC clock rate.
-f:       (deprecated) Set fifo input.
-g:       Set computation gain mode: 0 FIX, 1 MAX, 2 VAR
-h:       Print this help.
-l:       Loop file when reach end of file.
-r:       Set output sampling rate (default: 2048000).