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Signal Viewer – user guide

Signal Viewer shows recorded signals – test runs, flight logs, simulation output – as plots you can zoom, measure and compare. Everything runs on your computer; nothing is sent anywhere.

1. Start

  • Windows: install SignalViewer-Setup-X.Y.Z.exe (for you only, no administrator rights), or extract the portable .zip and double-click Signal Viewer.bat.
  • Linux / macOS: extract the -portable.7z and run SignalViewer/SignalViewer.
  • The first screen offers examples (a drone flight, the same mission flown twice, three car runs, an ArduPilot log). One click opens one ready to look at – the quickest way to learn the app.

2. Open your files

  • + Open files in the file list (Ctrl+O), or drop files on the window. CSV and text tables, MATLAB .mat, ArduPilot .bin, PX4 .ulg, MAVLink .tlog, ROS 2 .mcap, HDF5 and Parquet are read directly.
  • From Windows Explorer: right-click a file → Open with → Signal Viewer. If the app is already open, the file opens in it.
  • Ctrl+P (recent and favourites) lists the files and folders you used lately.
  • A CSV with an unusual layout: tick Show import options before opening in the open dialog to choose the delimiter, the time column and the header row, with a live preview.

Each file gets a colour and a short tag (A, B, C…). Signals of the same name from several files are told apart by them.

3. The screen

  • Left: the panels – Data (the open files and their signals), Create signals, Compare runs, Report, and for flight logs Flight log and Fleet.
  • Middle: the plots of the current tab. Tabs are at the top; the layout button (1 × 1) splits a tab into rows and columns.
  • Bottom: the timeline – play, the time shown, the cursor. Time is written in seconds as recorded, like the axes; Settings (the gear, Ctrl+,) can show a clock from the start instead, and holds the theme and the text size.
  • Right: the Inspector – values at the cursor, statistics, the selected signal's settings.

4. Plot

  • Click a signal in the list to add it to the active plot (the one with the coloured frame), or drag it onto any plot. Drop on a plot's right or bottom edge to make a new plot there.
  • The button next to the plot's title (Time ▾) changes the plot's type: Time, X-Y, XYZ, Map, 3D, FFT, Spectrogram, Envelope (many runs of one quantity), Video.
  • Right-click a legend chip for its options: second value axis, show as states, move, remove…
  • Right-click in the plot for: cursor here, note here, previous zoom, show everything, export the data, save or copy the image, axis limits.

5. Zoom and move

Do To
Drag on a plot zoom into that time range
Mouse wheel zoom around the pointer (Shift: values only, Ctrl: both, Alt: time only)
Wheel over an axis zoom only that axis
Alt + drag, or middle-drag move along the time axis
Double-click, or R show everything
Backspace the previous zoom

With Link X on (the default) every plot of the tab shows the same time; Link Y does the same for the values.

6. Measure

  • Space turns the cursor on; click to place it; ← → step sample by sample.
  • D adds a second cursor: the Inspector then shows the difference and the statistics between the two (min, max, mean, RMS…).
  • Put the cursor on a moment and press N to write a note there; with two cursors the note covers the time between them (shaded). Notes show on every time plot and in the report.

7. Compare runs

  • Open the runs together; plots show each signal once per file, in the file's colour.
  • Compare runs (left) compares each signal with a baseline run (or the mean of the runs): RMS and largest difference, correlation, a tolerance; its table lists every signal found in two or more files, the worst first.
  • Runs recorded with a time shift: right-click a file → Align time with another file.
  • The work you did on one file, for another: right-click the file you worked on → Copy the work to another file…, choose a file that is open already or one to open, and what to copy: its changes (ƒ), the signals made from it, its signals in the plots (on the same plots to compare, beside each plot in the same tab, or in a copy of each tab) - any of them. Again for a third file, and a fourth.
  • Undo one file's work only: right-click it → Clear this file: its signals out of the plots, its changes undone, the signals made from it deleted - one of them or all. The other files keep theirs.
  • Keep the files together with the two link buttons at the top of the file list: Link plots (a signal added or removed in one file is added or removed in all of them) and Link operations (a change on a signal, or a new signal made from it, is made on the same signal of every file). Each one is on or off by itself.

8. Create signals

Create signals (left) makes new signals from existing ones: a formula with the signals' names (Speed * 3.6, deriv(Altitude), lowpass(Roll, 5)…), filters, unit changes, frame conversions, a Python function of your own. They behave like recorded signals and are kept with the session. With Two signals and A − B the panel also tells how far apart A and B are – overall and for each stretch of a state such as the flight mode (a simulation against the flight, a model against the test).

An expression of x with other signals: wherever you write an expression of x (Change this signal…, or One signal → Expression in x here), another signal is written by its name: sin(x) + Speed. It is the signal of the same file as x - for several selected signals, each one's own file - as read from the file, so on a group that includes Speed itself, every one sees the same Speed. Copied or linked to another file, it reads that file's Speed. To take it from one particular file for all of them, name the file: x + {run_b.csv:Speed}. Names with spaces or brackets go in braces: {Speed [km/h]}.

A new signal made from two files belongs to the file of x (or, in a Formula, of the names written without a file); a source written with its file - and the baseline of a Compare runs difference - is kept. So when the work is copied to a new run, the new run gets its own signal against the same fixed source.

9. Keep and share your work

  • Save session (the disk icon at the top left, Ctrl+S; opening one: the folder icon next to it, Ctrl+Shift+O) keeps everything – files, tabs, plots, zoom, notes. The app also restores your last work by itself when it starts.
  • Templates (top bar): save a tab or a whole set of tabs as a template, and open it later on other files with the same signals.
  • Report (left): a report of the plots, statistics and notes – previewed in the app, saved as interactive HTML, PDF or Word.
  • A plot's ⋯ menu: export the data (CSV), save the image (PNG, SVG), copy the image.
  • Clear ▾ (the top bar): this tab's plots, the other tabs, all tabs, or all the work on the data - tabs, notes, derived signals and edits - while the files stay open. Each is undone with Undo in the message or Ctrl+Z. Everything also closes the files (it asks first).

10. Flight logs

ArduPilot and PX4 logs open with ready views (attitude, rates, vibration, battery, GPS, the map and the flight modes as coloured lanes) and a health check that points at what is worth a look. The Flight log panel lists the messages, events and parameters.

11. Live data

Live (top bar) follows files that are still being written – a CSV growing, a MATLAB file saved again and again – and can connect to a MAVLink stream. From Python, signalviewer_push.show(...) sends arrays straight into the running app.

12. When something goes wrong

  • Help → Copy error details copies the version, the system and the end of the log; paste it into your report. Nothing is sent automatically.
  • Help → Report a problem… copies the same details and opens the bug report form on GitHub in your browser - paste them there.
  • Help → Keyboard shortcuts (?) lists every key and mouse gesture.
  • Windows warns about an unknown publisher on the first start: More info → Run anyway.
  • macOS refuses to open it the first time: right-click → Open, or run xattr -dr com.apple.quarantine SignalViewer once.