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Contesting & Propagation Predictions

A short paragraph in the Nov/Dec edition of the National Contest Journal caught my eye in the Little Pistols section.  This is a quote from John VE3EJ commenting on part of his preparation for the WRTC-2014 held earlier this year:

“Propagation prediction software from K6TU, as well as VOACAP, was used to get a feeling, prior to the contest, for what might happened during the event.  I think that these are great tools, as long as they are used as flags for what might happen, rather that what will happen.

Working with many major DXpeditions like FT5ZM, NH8S, FT4TA, VU4KV, T33A… over the past year or so has reinforced John’s experiences with WRTC-2104.  The leaders of these DXpeditions confirm that the predictions were really helpful in initial planning and establishing the BIG PICTURE.  That big picture quickly got modified by on-air experience as the DXpedition progressed.

Establishing a valid BIG PICTURE requires two things - modeling the transmit antenna and power levels per band as accurately as time and energy permits coupled with a full 24 hours set of predictions for each band.

Seeing a full set of propagation predictions for a day allows you to see how propagation is likely to change as the day progresses.  When weighted with the same data for other bands, you can develop a plan of how changing propagation should impact band changes.

Here’s an animated GIF that shows what I mean:

ALL

To get this visibility you need to generate a full 24 hours of predictions and have the ability to page through them quickly - it doesn't need to be an animated GIF!  I included that just to show the visual picture you can gain from cycling through the hours.

To really get the best effect, its good to have an option to cycle through multiple bands at the same time - for example like this from Sweepstakes 2014 planning at K6TU (but without animation this time!).

4upNow you can see how the picture changes across multiple bands by the hour.

You are set and ready to go off to battle in the contest!  Remembering of course that no battle plan survives its first encounter with the enemy...

The other critical ingredient is how you specify the antennas to be used by the underlying VOACAP software.  Ideally, for HF antennas, you want to take the time to model your specific antenna (yagi and height above ground) over your specific terrain.  The ARRL HF Terrain Analysis (HFTA) program developed by Dean N6BV allows you to do this by accessing one of the sources of Digital Elevation Model (DEM) data on the Internet.  I developed an add-on to work with HFTA so that I can automatiaclly build a VOACAP antenna model for each location in which I am interested.  

The combination of the specific antenna modelled over real terrain coupled with the big picture of each band across all 24 hours works exceptionally well to develop the big picture.

If you are looking for another competitive edge in your contesting, this should be on your to-do list!  If you want to generate these predictions in less than 3 minutes, then take a look at K6TU.NET - my propagation as a service web site.  Fill in a few forms, click the RUN button - no software to download and results typically in 3 to 5 minutes.

Propagation predictions the easy way!

 

 

 

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STU PHILLIPS
MENLO PARK, CALIFORNIA

Intense Brit, lived in Silicon Valley since 1984. Avid pilot, like digital photography, ham radio and a bunch of other stuff. Official Geek.

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