Full-Scale Range Dialog

Controls: Calibration Menu >> Full-Scale Range
Macro : RangeDlg

You can invoke this dialog from the Calibrate menu via ALT+C, R, or directly via CTRL+R.

This allows you to enter absolute calibration data for the sound card inputs and outputs. This information is needed in addition to the relative calibration of the attenuators in the sound card's mixer obtained via the Auto-Calibration dialog. The Range controls have no effect without relative calibration.

Range information is stored with attenuator calibration information in the Daqarta0.ATN file that is loaded when Daqarta starts. If you make any changes to Range values, you will be prompted to save them when you exit Daqarta. If your system has more than one card (which you can select via the Device controls in the Start Preferences dialog), then the files may be called Daqarta1.ATN, etc. Note that the Output Device number is used here. The Input Device number is usually (but not always) the same.

The Daqartan value may also be changed via shortcut command-line parameters for use with multiple desktop icons when managing multiple devices.

The value to be entered for each line in the Range dialog is the level of a signal that will just produce a full-scale response on the most-sensitive Input range. For Outputs, the value to be entered is the maximum level produced when the Generator is creating a full-scale signal. In both cases, "level" means amplitude in the mathematical sense of half the peak-to-peak difference of a symmetrical waveform like a sine wave. The default value of 1.000 implies that the wave runs between +1.000 volts and -1.000 volts. In other words, this is not an RMS value such as you might read from the AC range on a voltmeter.

The internal format for the Range value supports about 5 integer digits and 5 fraction digits. If you need to enter a very small value like 0.58 mV (0.00058 V), enter 0.58 here and enter 1000 for External Gain.

A given Range entry applies equally to both Left and Right channels, which are assumed to be identical inside the sound card. Use the External Gain dialog for any external amplification or attenuation you provide.

There are separate Stereo and Mono entries for Input lines. Most sound card inputs sum the Left and Right channels together when only one is active, and cut the sensitivity in half. So, the Mono Range entry should typically be twice the value of the Stereo Range entry.

Use single-channel Input operation with caution, to prevent contamination by the other channel. Be sure to set the other Line Level (and Master Level, if present) to minimum (most-negative value). Note that this may not completely shut off that channel, so you may need to insure that there is no signal present at that input.

There are two basic approaches to obtaining full-scale range values: You can start by measuring the Generator output with an external voltmeter and setting the Output Range, then apply the now-calibrated signal to the input to get the Input Range. Or, you can start by applying a known input signal to calibrate the Input Range and then use that to read the Generator output to determine the Output Range.

The Output Voltage Method is preferable if you have a sensitive meter; the Input Voltage Method is suitable for use with inexpensive meters.

Some sound cards invert signal polarity on input or output channels, or both. Be sure to see Polarity Determination to insure that the trace display matches the real world.