Miscellaneous Parameters

The above toolbar contains (from left to right):

Invert Input Signal button, Channel A Zeroing button, Channel B Zeroing button, Windows Recording Control, Windows Volume Control, Play button, Cyclic Play button, Internal Gain indicator, Probe A Current Switch Position, Probe B Current Switch Position, and Input Peak Level Indicators for Channel A and Channel B.

Invert Input Signal

If the button is depressed, the input signal will be inverted by the software just after A/D conversion, e.g. +1V will become -1V after the inversion. All the subsequent processing such as triggering, data analysis and display will be performed based on the inverted signal.

The button is in released state by factory default.

Zeroing

If the input of a sound card channel is connected to its ground, the oscilloscope should display a straight horizontal line at 0 V. However, this may not always be the case. Some sound card, if not compensated by software, may display an offset voltage when its input is actually at the ground level. Therefore, there is a need to compensate this offset for these sound cards.

: This button will only be enabled when the oscilloscope is in running state and the Trigger Mode is "Auto". Once pressed, a message box will pop up with three options: Yes, No, Cancel. You will need to connect the input for Channel A to the ground before you choose Yes, in order to set the ground level for Channel A to zero. If you select No, then the ground level will be reset to its default value (i.e. no compensation). You may choose Cancel to cancel the operation.

: This button will only be enabled when the oscilloscope is in running state, the Trigger Mode is "Auto" and the Sampling Channels is "A&B". Once pressed, a message box will pop up with three options: Yes, No, Cancel. You will need to connect the input for Channel B to the ground before you choose Yes, in order to set the ground level for Channel B to zero. If you select No, then the ground level will be reset to its default value (i.e. no compensation). You may choose Cancel to cancel the operation.

Windows Recording Control

A typcial Windows Recording Control is shown in the above figure. Different sound cards may have different items in the Recording Control.

When accessing Windows Recording Control from Windows Control Panel, you need to choose the sound card to be used for data acquisition first if multiple sound cards exist.

When pressing the button in the Miscellenous Toolbar of the software, the Recording Control of the sound card used by the software for data acquisition will be openned. If multiple sound cards exist, you can configure the sound card to be used at [Setting]>[Calibration]>[Input Sound Card].

From the Recording Control, you can configure the input sources for data acquisition. The input source can be CD Player, Microphone, Line In, Wave Out Mix, etc, depending on the sound card used. To test an external electrical signal, either Mic Input or Line In should be used. Wave Out Mix (sometimes called “What U Hear” or something similar) can be used to get the signal being output by the sound card. You can select it as the input source for data acquisition in order to analyze and display what is being output by the Signal Generator. This, in fact, switches the software into simulation mode with the loopback at the sound card mixer level.

The internal gain can be adjusted by moving the volume slider corresponding to the input source selected for data acquisition. For Microphone, it is usually possible to further adjust the internal gain by selecting/removing Mic Boost in the Advanced Controls for Microphone as shown below. Normally selecting Mic Boost will increase the internal gain by 10 times (i.e. 20dB).

Windows Volume Control

A typcial Windows Volume Control is shown in the above figure. Different sound cards may have different items in the Volume Cotrol.

When accessing Windows Volume Control from Windows Control Panel, you need to choose the sound card to be used for signal output first if multiple sound cards exist.

When pressing the button from the Miscellenous Toolbar of the software, the Volume Control of the sound card used by the software for signal output will be openned. If multiple sound cards exist, you can configure the sound card to be used at [Setting]>[Calibration]>[Output Sound Card].

From the Volume Control, you can configure the input sources for signal output. For the Signal Generator, all input sources for signal output should be muted except the Volume Control and Wave, in order to to minimize the unwanted noises. The output volume can be adjusted by either the Volume Control slider or Wave slider.

Waveform Play

The waveform displayed in the Oscilloscope can be played (output) by pressing the button in the Miscellaneous Toolbar.

Waveform Cyclic Play

The waveform displayed in the Oscilloscope can be cyclically played (output) by pressing the button in the Miscellaneous Toolbar. Releasing this toggle button will stop the cyclic playing.

Internal Gain Indicator

The above indicator in the Miscellaneous Toolbar shows the internal gain setting which is adjustable via Windows Recording Control. When the input source for data acquisition is neither Microphone nor Line In (e.g. CD Player…), the indicator will simply show “Not Mic/Line In”.

Probe Current Switch Position

The two combo boxes on the right hand side of "Probe" in the Miscellaneous Toolbar allow you to select the probe attenuation factors corresponding to the current attenuation switch position on your probes or test leads. The left one is for Channel A and the right one is for Channel B. You can have at most three switch positions. The dedicated sound card oscilloscope probe supplied by Virtins Technology is best suited for this application.

Note that these two combo boxes only allow you to select the corresponding attenuation factors, they will not set the switch position on the probes for you. You have to set it manually.

The actual attenuation factors can be accessed and set via [Setting]>[Calibration] and will be introduced later in this document.

Input Peak Level Indicator

The above two Input Peak Level Indicators reflect the peak level of the frame of data acquired, the upper one is for Channel A and the lower one is for Channel B. It is expressed as a percentage of the ADC full-scale voltage. The color of the indicator changes gradually from green to orange as the percentage goes from 0% to 100%.

If the Input Peak Level is equal to 100%, it is recommended to lower the internal gain, increase external attenuation, or lower the signal under test directly, in order to avoid peak clipping from happening.