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Geocoding the Spectra Dataset

The callboook data is derived from various linked tables in the downloaded Spectra dataset. The Spectra dataset does not contain positional information, however, despite its usefulness for Amateur Radio mapping applications. The process of adding positional information to an address is called 'Geocoding'. An address can be geocoded in various ways, depending on the desired level of accuracy:

You could stand in each ham's back yard with a GPS receiver: this would give the best level of accuracy, but would be time consuming, expensive, and completely impractical.

You could ask each ham to tell you their position, but this would be unreliable as well as hugely time consuming.

You can use a geo-coding service that provides the position from a given address: this works well, but requires a certain amount of manual address preparation beforehand, and examination of the returned results afterwards to understand how well the geocoding service has interpreted each address-line, and what level of accuracy it thinks is valid: rooftop, street, suburb, town, state, or in the worst case: country! Such services generally require payment, or have a limited number of free sessions. They also require an individual registration for each user.

You can match the postcode in an address with a table of latitude and longitude positions for each postcode. In Australia, postcodes are sub-divided amongst a number of suburbs, so it is necessary to match both suburb and postcode to obtain a fix. The area covered by a suburb/postcode position varies, but is not tiny. It is not possible to get a fix on each ham's backyard this way, but the level of accuracy obtained is more than sufficient for most Amateur Radio mapping needs, and also provides a level of privacy that address-line geocoding will remove. For this reason, postcode geocoding was the method chosen in this automatic callbook application.