TYPE: CHOP
TITLE: Spectrum CHOP

This CHOP calculates the frequency spectrum of the input channels, or a
portion of the channels. The spectrum can be manipulated and then converted
back to get a filtered signal.

When converting a signal to its spectrum, two channels are created from the
one containing the signal. One channel contains the magnitude of the frequency
components, and the other contains the phase. The channels are named 
"<channel name><suffix>", where <suffix> is the magnitude or phase suffix.

To determine the frequency that a given sample represents, use the formula:
~c(
Freq = 2 x (sample#) x (Sample Rate) / (Channel Length)
~c)

Where 'Sample Rate' and 'Channel Length' both refer to the Spectrum CHOP's rate
and length.

To analyze the frequency spectrum of a signal use only the magnitude channel;
the phase channel does not contain useful information for analysis (but is
needed for converting the spectrum back to its original signal). 

In order to convert back to a signal, both channels are required. The suffixes
should be the same as those used in the previous spectrum CHOP. 

There are no local variables.

Parameters
    Convert          - Determines whether to calculate the frequency 
		       spectrum from a signal, or reconstruct a 
		       signal from a frequency spectrum.
    Convert Entire Channel   - If on, the spectrum is computed for the entire 
                       channel. Otherwise, segments of the channel
		       can be analyzed.
    Unit Values      - Determines how Start/End parameters are 
		       interpreted.
	Absolute              - The segment is the start/end values.
	Relative to Start/End - The segment is a shift from the old 
				positions of the input's start/end.
	Relative to Current Frame - The segment is a shift from the current
	                        frame.
    Start            - Determines the start of the segment to be     /start
		       analyzed (in Units).
    End              - Determines the end of the segment to be       /end
		       analyzed (in Units).
    Magnitude Suffix - When converting to a spectrum, the string
		       appended to the channel name that identifies
		       the channel as containing magnitudes.
    Phase Suffix     - Similar to Magnitude Suffix, but for phase
		       channels.
