HF Systems
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HomeHF SystemsAustralasiaHAP Charts Monday, May 27 2024 09:19 UT

HAP Charts

Hourly Area Prediction (HAP) charts are designed for communications between a specified base and mobile within a nominated area. If the base operator is separated from the base antenna, the location of the base antenna should be specified as the HAP chart base. For example, if communications are required between a mobile located somewhere within Australia and an operator located in Sydney whose antenna is located in Brisbane, the correct location of the HAP chart base is Brisbane.

HAP charts are available in several forms:

ASWFC HAP charts have the following features.

  • Each chart shows colours which represent the recommended HF frequencies for contacting the base or mobile within the area bounded by the chart for a particular hour. The base operator and the mobile should use the SAME frequency denoted by the colour at the location of the mobile.
  • The geographic zone, which is variable, is represented by a map showing latitude and longitude.
  • Charts are in Universal Time (UT).
  • Daily HAP charts use the ASWFC world ionospheric (median) maps and can be for any place, time, or ionospheric support level. The daily HAP charts presented here are for the current UT day and were produced using the ASWFC daily forecast T index. You can produce your own HAP charts from our on line HF prediction tools.
  • HAP charts use the regional real time foF2 (vertical MUF) map and are restricted in area, and time to that of the real time map. The real time map should track ionospheric storms, this means that the real time maps may contain storm gradients (variations in vertical MUF with location) that are not present in the median ionospheric maps. The real time HAPs can be different to the daily HAPs for the same hour, as the underlying maps may be different, particularly when the ionosphere is disturbed.
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