You are here: NI Home > Support > Product Reference > Manuals > LabVIEW 8.6 FPGA Module Help

Owning Palette: FPGA Math & Analysis VIs

Installed With: FPGA Module

Minimizes spectral leakage associated with truncated waveforms. Use this Express VI before you use the FFT Express VI.

Details  

Dialog Box Options

Block Diagram Inputs

Block Diagram Outputs

Dialog Box Options

Parameter	Description
Window Configuration	Contains the following options: Type—Specifies the type of window. You can select from the following: Hanning Hamming Blackman-Harris Exact Blackman Blackman Flat Top 4 Term B-Harris 7 Term B-Harris Low Sidelobe Length—Specifies the length of the window. The range of Length is [2,8192].
Output Data Type	Contains the following options: Adapt to source—Specifies whether the Express VI decides the output data type. Do not place a checkmark in this checkbox if you want to use the Word length control to determine the output data type. Word length—Specifies any output word length in the range of [1, 32]. This control is available only if you did not place a checkmark in the Adapt to source checkbox. Integer word length—Indicates the output integer word length that the Express VI calculates.
Implementation	Contains the following options: Show coefficient index terminal—Specifies whether you specify the indices of the window coefficients in the coefficient index terminal. If you do not place a check mark in this checkbox, the Express VI automatically indexes the window coefficients. Show reset terminal—Specifies whether this Express VI includes a reset input on the block diagram to reset the Express VI at run time. You can save resources on the FPGA if you do not place a checkmark in the Show reset terminal checkbox.
Window Coefficients	Window Coefficients—Displays the values of the window coefficients.
Execution	Contains the following options: Outside single-cycle Timed Loop—Specifies that the Express VI runs outside the single-cycle Timed Loop. Inside single-cycle Timed Loop—Specifies that the Express VI runs inside the single-cycle Timed Loop. Selecting Inside single-cycle Timed Loop makes the handshaking signals available for use. Refer to Scheduling Timing Using Handshaking Signals for information about using the handshaking signals available for this Express VI.

Block Diagram Inputs

Parameter	Description
reset	Specifies whether to reset the auto-indexing process. Inside the single-cycle Timed Loop, reset ignores the incoming data point during the reset cycle. This terminal is available only if you have placed a checkmark in the Show reset terminal checkbox on the configuration dialog box.
real data in	Specifies the real part of the input signal.
imaginary data in	Specifies the imaginary part of the input signal. Leave this terminal unwired to read only real data.
coefficient index	Specifies the window coefficient index. This terminal is available only if you placed a checkmark in the Show coefficient index checkbox on the configuration dialog box.
input valid	Specifies that the next data point has arrived for processing. This terminal is available only when you have selected Inside single-cycle Timed Loop. The input valid terminal is required inside the single-cycle Timed Loop.
ready for output	Specifies that the rest of the block diagram is ready for the Express VI to output a new value. The default is TRUE. This terminal is available only when you have selected Inside single-cycle Timed Loop. Note  If this signal is FALSE on a given cycle, the output valid signal is also FALSE for that cycle.

Block Diagram Outputs

Parameter	Description
data index	Indicates the current window coefficient index corresponding to the current output. When running the Express VI inside the single-cycle Timed Loop, ignore this value if output valid is FALSE. You can use this output for debugging.
real data out	Returns the real part of the windowed signal.
imaginary data out	Returns the imaginary part of the windowed signal.
output valid	Indicates that the Express VI has updated the current data point and the data point is ready to be used by downstream LabVIEW objects.
ready for input	Indicates that the Express VI is ready to accept new input data. This terminal is available only when you are using the Express VI inside the single-cycle Timed Loop. Note  If this signal is FALSE on a given cycle, the Express VI does not accept data on the following cycle. If input valid is TRUE on the following cycle, the input data is lost.

Scaled Window Details

This Express VI scales the windowed time-domain signal so that when a LabVIEW object computes the power or amplitude spectrum of the windowed waveform, all windows provide the same level within the accuracy constraints of the output wavelength.

Note  Refer to Scheduling Timing Using Handshaking Signals for information about using the handshaking signals available for this Express VI.