The O-Scope modules provide the ability of several pieces of bench equipment suitable for working with audio equipment. These abilities include oscilloscope waveform display, voltage calculations, and frequency spectrum display.
Most of these can be observed without additional test equipment. Clipping and signal levels are usually best observed using a common function generator. Low level ripple and system noise viewing can be improved by the addition of a low voltage differential probe.
O-Scopes provide a variety of voltage calculations. These include peak and minimum voltages, VDC average voltage, true Vrms AC voltage, and peak to peak voltage. The O-Scope II also provides a VdB decibel voltage calculation which is based on the assumption of a 600 Ohm circuit (0 dB is defined as 1 milliWatt into 600 Ohms or 0.774 Vrms).
Since the Vrms calculation is based upon a true rms approach rather than making assumptions about the shape of the waveform, this calculation is far more accurate than most digital voltmeters, which do not display true Vrms or have an AC frequency range substantially beyond 60 Hz.
The peak and minimum voltage measurements provide information as to the maximum and minimum voltages detected in the sweep. Again, these are measurements not normally available from digital voltmeters. These measurements provide useful information in power supply testing as well as in peak measurements for audio signal.
O-Scopes provide frequency spectrum capabilities. These can be used to determine the frequency response of a system or effects of filters (such as rumble, bass and trebble, or graphic equalizer adjustments) upon the system frequency response. A white noise generator or pulse generator is necessary for making frequency response measurements.
Distortion may also be measured using the O-Scope. It requires feeding a low distortion sine wave generator signal into the system and observing harmonics in the system output. Note that most low cost sine wave generators have significant distortion to begin with and are not suitable for such measurements.
The O-Scopes provide a dynamic range of up to about 50dB (between peak signal level and the minimum measurable signal components) which is suitable for measuring distortion levels slightly under 1%. By using a notch filter device to reduce the original test frequency signal component, it is possible to increase the dynamic range by the amount of this notch filter attenuation so that much lower levels of distortion may be measured. Such an effort does require a very low distortion sine wave generator, typically single frequency devices. The O-Scope is also capable of measuring the attenuation of the notch filter.