Oscilloscope
A two-channel oscilloscope. It shows the waveforms reaching its inputs over a time span, with a band for their noise, or, in Roll mode, how a level changes as a sweep plays.
Ports
Two inputs, ch1 (red) and ch2 (blue). It has no outputs.
The model
Normal
Each channel is rebuilt from its DC and tones over the time span,
\[v(t) = v_\text{DC} + \sum_j \operatorname{Re}\!\left(c_j\, e^{i 2\pi f_j t}\right),\]from \(t = 0\), where every generator’s cycle starts. Round it is a band of \(\pm 1\sigma\) for the noise, the rms of the noise density up to the scope’s 100 MHz bandwidth. A tone too fast to draw over the span fills a lighter band as wide as its swing, as on a real scope. On auto the span is three periods of the slowest tone.
Roll
Roll shows the level recorded as a parameter sweep plays, over the last span of the sweep’s clock (10 s on auto). Slow changes, a mirror scanning or a laser tuning, show as they happen. When nothing changes the trace is flat, with the same bands.
Scales
Each channel has its own vertical scale, channel 1’s on the left and channel 2’s down the right, on eight divisions. Each is set as so much a division about an offset (the level at the centre line), or left at 0 for auto.
Settings
| Field | Default | Meaning |
|---|---|---|
mode | "normal" | Mode: "normal" (Normal), "roll" (Roll) |
span | 0.005 | Time span (s; 0: auto) |
v1div | 0 | Ch1 per division (0: auto) |
v1off | 0 | Ch1 offset |
v2div | 0 | Ch2 per division (0: auto) |
v2off | 0 | Ch2 offset |
From the tool's own tables, file format version 1: the names are those in a .jekray file.
Readouts
Its panel draws the traces, which can be saved as a picture (PNG) or as their numbers (CSV).
Assumptions
- The steady state only: the trace is what the circuit settles to, not a transient after a change.
- Noise is drawn as a band, not as a random trace.
- Its inputs do not load the circuit.
Related
- Spectrum analyser.
- Photodetector, whose Signal views share this scope.