Interactive HTML reports embed signals longer than 150,000 samples as three min/max levels, so very deep zoom inside the report shows less detail than the app.
Copying an image to the clipboard depends on the window's clipboard support; Save image always works.
A derived signal whose source file was closed stays in the list, marked, until you remove it.
The macOS package is not signed or notarized: after extracting, run xattr -dr com.apple.quarantine SignalViewer (or right-click → Open) the first time.
Without pyarrow the pandas parser keeps a malformed row that has too few fields (missing values become empty), while pyarrow skips it.
The timeline's modes apply to time, X-Y, map and spectrogram plots, not to FFT.
In a web browser (not the desktop window) Ctrl+PageUp / Ctrl+PageDown and Ctrl+Tab switch the browser's own tabs; use the All tabs list or Go to tab (Ctrl+K) there.
The right value axis follows its data: zooming the values (Shift+drag), panning, the axis limits dialog and linked value axes act on the left axis.
Open with (Explorer) is set up by the installer; with the portable packages, open files from the app or SignalViewer file….
Installed with pip it opens in the browser (with signalviewer-lite, only the core readers are there until their extras are added - the app says which); pip install "signalviewer[desktop]" gives it its own window (on Linux that needs GTK or Qt).
The interactive HTML report lists the notes under its summary; it does not draw them on its plots (the PDF and Word reports do).
Columns with a time column of their own keep that column's unit: a time_boot_ms column stays in milliseconds (as the main time column always has), so it does not line up with a time in seconds.
CAN: candump logs, Vector ASC (classic CAN lines) and CAN tables in CSV are read; CAN FD lines in ASC files, .blf and MF4 are not. The same id on two buses is decoded as one message.
Binary layouts (ICD): fixed fields, bit fields and value names; no checksums (a damaged packet with a good sync and length is read), no arrays or strings inside a payload, no packets whose layout depends on a field.
Your own readers run inside the app: a reader that hangs holds the opening of that file (the rest of the app keeps working); files read by a reader are reloaded whole in live mode, not appended.
A spectrum (FFT, Welch, spectrogram) of a signal with gaps bridges them with straight lines on an even time grid: the frequencies are right, but amplitudes are lower by about the share of time the gaps cover. For exact amplitudes put the two cursors on a stretch without gaps.
Telemetry logs (.tlog): messages that carry the autopilot's clock are placed on it (one offset per boot, the median radio delay); messages without it are at their receive time, so they include each packet's radio delay. Live, a boot's offset is learned from its first data and then kept.