Local Area Mobile Predictions or LAMPs are designed for communications between a base and a mobile. There is no geographical information on the charts as there is only one ionospheric control point restricting the mobile to being within 1000 km of the base. The charts can also be used for communications between two mobiles that are both within 300 km of the base (use the distance between the two mobiles when reading the recommended frequency from the charts).
In cases where the base operator and the base antenna are not co-located, the location of the base antenna should be specified as the base location and distances from the mobile to the base antenna used in determining the appropriate frequency. For example, if the base operator is located in Darwin but the base antenna is located in Tennant Creek, then Tennant Creek should be specified as the base in the LAMP chart.
SWS LAMP charts have the following features.
- Predictions are in Universal Time (UT).
- Distance is shown in kilometres.
- Frequencies are in megahertz (MHz).
- The recommended frequency can be determined by looking up the intersection between time and distance on the chart.