Virtual channels

Virtual channels hold waveforms calculated from existing channels, as defined by user-supplied expressions. Calculations can be simple sums, products, differences or ratios of channels, or use mathematical functions. Like channel processes, they are applied dynamically both on-line and off-line.

• Define data using arithmetic operations and values
• Manually enter expressions or create using drop down menus
• Display results of multi-channel waveform arithmetic
• Cubic spline interpolation used if channels have different sample rates
• Spectral functions show how particular features of the power spectrum of an input channel change over time
• Spectral functions include power in frequency bands, spectral edge, mean frequency and dominant frequency

• Generate waveform display of event frequencies using smoothing by Gaussians, sinusoids, triangles or rectangles, or interpolation of instantaneous frequency
• Create evenly sampled data derived from unevenly sampled measurements
• Apply arithmetic functions e.g square, square root, cube, absolute values, half-wave rectification and trig functions (sin, cos, tan, arc tan)
• Waveform generation: sine, square, triangle, sawtooth, envelope