North American Overlay Mapping
Layer Notes - Radio Amateurs
The 'Hams' foreground overlay is used with only two maps: Overview East and Overview West. It shows a map of points indicating the presence of Radio Amateurs in the USA and Canada.
The US part of the overlay was created with the latest callsign data from the Federal Communications Commission's (FCC) Wireless Telecommunications Bureau's Universal Licensing System (ULS). The Canadian part of the overlay was created with the latest callsign data from the Industry Canada's Call Sign Database, available to download on the RAC website.
Both files were combined with a Zipcode database to provide a latitude/longitude position for each Amateur in the callsign database, the accuracy depending on the zipcode centroid. These were then plotted with specialist GIS software.
Note: For clarity, it was decided to take no account of the numbers of amateurs present in each 5-digit zipcode or postal-code entity. Each dot show a centroid where 1 or more amateurs have registered their addresses.