Controls: Options Menu >> Frequency Counter
Macro: FcountDlg

The Frequency Counter dialog can be invoked from the Options Menu or toggled open or closed directly via CTRL+F. It enables the usual frequency, period, and event totalizing measurement functions of a conventional benchtop counter, plus a special spectral event counter. The frequency measurements employ special techniques to allow much higher resolution than conventional frequency counters at low signal frequencies.

• Fast/Med/Slow - Measurement update rate
• Hertz - Frequency measurement
• msec - Period measurement
• Total - Event counting
• SpecTot - Spectral event counting
• Reset - Clear Total or SpecTot count
• Decimal Places

Besides the functions selected from the Frequency Counter dialog, operation also depends upon the settings of the Trigger dialog. In general, the mode should be set to Normal. The Trigger Source selects the channel to be measured, while Trigger Slope and Level set the threshold for detection just as in a benchtop counter.

Trigger Hysteresis is very important for proper counter operation in the presence of noise. Usually, you will want to set this to slightly more than the peak-to-peak noise level. You can drag the dotted horizontal cursors that appear when the Trigger dialog is visible until you get a stable reading.

Trigger Holdoff should usually be set to zero for normal frequency or period counting, but it can be very useful for Total and SpecTot operation, or for measuring burst rates or periods without confusion from the burst carrier frequency.

Trigger must be active for the Frequency Counter to function, except in SpecTot mode. If Trigger Single is selected, the counter will only update each time Trigger is activated.

For high frequencies (say, over 10 kHz), Trigger Level should be near zero for best results. Since there must be one sample on the slope before the trigger sample, and there are fewer samples per cycle at high frequencies, this reduces the chance that the next sample will fall past the peak and possibly be lower than the Level value.

Note that although the same Trigger settings also control the start of the trace, the Frequency Counter scans all incoming data for trigger events, including those that are shown within the trace and those that are not shown between traces.

Besides live data, all of the Frequency Counter functions can operate with long ( DDisk) data files. This allows you to measure frequency (or period) or count events on pre-existing files, including .WAV files which may have been acquired on other systems.

The Frequency Counter dialog can be positioned by dragging its title bar in the usual Windows manner. The position and size will be maintained independently from other Daqarta dialogs, and will be saved across Daqarta sessions.

Unlike most Daqarta dialogs, the dialog size can be changed by dragging the borders. The numerical display font will be scaled proportional to the height of the dialog, allowing creation of extra-large displays for distant viewing. (On the initial use, you may need to adjust the size for your screen.)

Due to the Trigger requirements, the Frequency Counter is best suited to waveforms that can provide a clean trigger determination based upon Level and Slope (except for SpecTot spectral event counting). When the signal is noisy or has multiple frequency components, use the Spectrum Peak cursor readout mode instead.

Spectrum Peak cursor mode doesn't provide the same ultimate frequency resolution as the Frequency Counter, especially at low frequencies. But it can still resolve to a fraction of a Hertz in most cases, without any Trigger requirements. That's especially important at high frequencies, where triggering the counter may be more difficult.

Note: To copy the Frequency Counter displayed value to the Windows Clipboard, left-click anywhere on the display. This captures a copy of the current value and pops up a message box allowing you to save it to the Clipboard.

Macro Notes:

FcountDlg=1 opens the Frequency Counter dialog, FcountDlg=0 closes it, and FcountDlg=x toggles between open and closed.

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