Sources & limits
Know what a point means before using it
dalMap combines independent community and public sources with calculations and static references. The source label, observation age, and caveat are part of the result—not fine print. “Live” means the latest observations received by the map, not confirmation that an operator is currently active or available.
Four kinds of map context
Submitted observations
Examples include PSK Reporter, WSPR, DX spots, APRS, and APRS weather. They can be incomplete, delayed, wrong, or stale.
Official observations and alerts
Examples include METAR, NDBC, NWS alerts, USGS earthquakes, and NHC storm centers. Authority and scope are specific to each source.
Calculated or modeled context
Examples include paths, grayline, passes, pointing, terrain clearance, space weather, and tropo potential. These depend on stated inputs and assumptions.
Static reference
Examples include zones, Maidenhead grids, civil time zones, representative DXCC locations, and city-light imagery. A reference is not a live operational claim.
The questions to ask
- Who supplied this? Select the marker or open its contextual help for the provider and the original information link.
- When was it observed, calculated, or published? Read the age and status. Arrival time is not necessarily observation time.
- What is this evidence actually about? An APRS position is where one station reported itself, not where it can be heard. A satellite footprint is geometry, not access. A model is a calculation from stated inputs, not a prediction.
- What important thing could be missing? Source outages, limited scope, provider coverage, retention limits, and filtering can all produce an incomplete view.
Current source register
The live map’s Data sources and terms page is the current public register. It identifies providers, attribution, material transformations, freshness behavior, privacy effects, licenses, and source-specific limits. It is the right place to check before relying on a particular layer or sharing its information.
Boundaries that protect operators and sources
dalMap uses documented providers and requests, respects source-specific terms, and avoids turning public radio reports into a tracking product. It does not post on your behalf, send radio commands, modify subscriptions, or use your browser-local radio, decoder, log, watch, or alert data as server-side state.