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Seattle Propagation

The following information is gathered from the Australian Bureau of Meteorology's Space Weather Services.

Notes on Pacific Daylight Saving Time:
Starts on the 2nd Sunday in March (-7 hours),
Ends on the 1st Sunday in November (-8 hours).
Double check your logging software after the time changes.

Federal Way Amateur Radio Club
P.O. Box 23415
Federal Way, WA  98093-3415

HAP Charts

Hourly Area Prediction (HAP) charts are designed for communications between a specified base station location, and another station located within a nominated area.  The HAP chart is a guide to frequency selection for HF communications between a specified station and a base station, in this case Seattle.  The recommended frequency for communications with the base at a given hour is read off from the point in the map corresponding to the mobile's location.  The predictions are made from real time data which are updated each hour.  If present, dashed lines delineate areas of unlikely communication.  

Ionospheric Map

The plot above shows a near real-time critical ionospheric frequency (foF2) map produced using automatically scaled ionogram profiles from the Australian region and around the world.  The above map can be used as a guide to NVIS ionospheric frequency support and to generate real time HF predictions (eg Hourly HAP charts) to assist the HF radio communicator.  A feature of the ionosphere is its ability to reflect radio waves. However, only radio waves within a certain frequency range will be reflected and this range varies with a number of factors.  This graphic updates every 15 minutes.

Grid Square Locator

VOACAP Point-to-Point Map

VOACAP Coverage Predictor Map

VOACAP DX Propagation Planner

VOACAP DX'pedition Prediction Charts

Seattle Azimuthal Map

Please note:  The day on the UTC/GMT clock is off
between UTC/GMT mid-night and local mid-night
for some reason.  They are working on it.

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