Advanced Delay Finder: A Guide

Advanced Delay Finder: A Guide

Within the Delay Finder window, you may have noticed an "Advanced" button. It opens the "Advanced Delay Finder" menu. (A guide to Smaart's Delay Finder function can be found here.)

This advanced version of the Delay Finder features an IR plot at the top, alongside input meters. Much like the IR plot in TF mode, you can select from ETC/Lin/Log views.

The Advanced Delay Finder is resizable and can stay open while you work in other Smaart windows.

This graph behaves identically to the regular IR plot.

• You can zoom in and out with the [-] and [=] hotkeys, alongside any other plot zoom controls.
• The cursor readout at the top of the plot features (from left to right) fixed cursor coordinates, movable cursor coordinates, and the delta between the two. 
• Fixed cursor position can be moved by holding [Ctrl/Cmd] while clicking on the graph. Doing so updates the found delay time to match the new position.
• The checkbox in the upper right corner of the graph runs a one-octave bandpass filter on the IR, centered on the frequency specified in the field to the right of the button. This is commonly the crossover frequency between two systems, but can be any frequency that you would like to isolate. 

The control group in the lower left corner contains the basic Delay Finder window controls.

• An IR measurement runs automatically when you open the Advanced Delay Finder window.
• The "Find" button re-runs the measurement. 
• The "Insert" button inserts the found delay time as the measurement time reference (measurement delay). 
• An advanced feature, the "Store" button adds the found delay time to the table.

The table below the graph is a relative delay time calculator.

• Checking the "TO" box next to any entry designates it as the time zero reference and recalculates all of the relative delta time and distance figures for other entries accordingly. 
• The up/down arrow buttons below the table move a selected entry up or down in its list. 
• The "Delete" button deletes the selected entry.
• The "Clear List" button deletes all entries from the table.

The "TF Pair" selector to the right of the table lets you select another transfer function signal pair to analyze. Note that changing this selection automatically re-runs the IR measurement. The meters show your measurement and reference signal levels for the selected input signal pair. The "Close" button closes the window.

Additional Settings

The FFT size and number of averages for the basic and advanced delay finder are set from the Delay Finder section of Transfer Function measurement settings (Options > Measurement Settings > Transfer Function).

The default setting is a 64K FFT with no averaging, equivalent to a time constant of 1365 ms at a 48k sampling rate. This is sufficient for finding delay times at distances up to ~450 ft (or ~140 m) from a source. The FFT time constant should be at least three times greater than the expected delay time. When measuring from extremely long distances or using a sample rate greater than 48k, you may need to increase the FFT size. Increasing the number of averages when working in a noisy environment may help as well.

If "Apply Threshold" is enabled, a -80 dBFS magnitude threshold will be applied to the "Delay Finder" calculations. This option is not recommended for measurements with low signal presence. If you're not satisfied with your delay times when using this option, we recommend disabling it or using "Track Delay" instead.