Propagation Planning for Contests

Propagation Planning for Contests

Using Propagation Predictions to Develop a Band Plan

Propagation planning for a contest effort is quite similar to propagation planning for a DXpedition (the latter work, titled Propagation Planning for DXpeditions, is available at ttp://www.arrl.org/tis/info/pdf/propplan.pdf).  For both, you need to know when the bands are open. What separates propagation planning for contesting from propagation planning for DXpeditions is the extra step for conte band that gives you the highest score } which may not necessarily be the band that gives you the highest rate. The goal of this article is to provide a 3-step process that generates an a priori contest band plan to maximize your score.

This process is only needed for contest categories that require a decision with respect to -multi with aedicated station and sufficient operators on each band, then this doesQ÷W DSSO\ - all you need are - all you need are propagation predictions for your band to your target areas. Neither of these categori The concept behind these steps is the fact that our propagation predictions are statistical to get an electromagnetic wave from point A to Point B is a probability, as is the comparison of the predicted Signal-to-Noise Ratio (SNR) to a user-selected criteria.

Multiplying these two probabilities together for the most important paths and picking the highest overall robability should statistically put you on the right band at the right time to maximize your score.

Will adhering to these steps make you a winner? Not necessarily. Competitive contesting requires efforts in many areas other than propagation. Understanding propagation is just one piece of the larger puzzle.

experienced contester operating from a familiar QTH in a familiar contest, these steps QTH (in terms of knowing when the bands are open) or are in an unfamiliar contest (unique point structure to different areas of the world), these steps should help improve your score.

/

Step 1: Know the Contest

In order to maximize your score, you need to intimately know the contest. You need to know whom you can work. You need to know what the multipliers are. And you need to understand the point structure of the contest to identify which contacts are most valuable. 

The only way I know how to do this is to sit down and carefully read the contest rules.

Take notes if necessary.

The output of this step is the high-level strategy that identifies which QSOs are most but some are more important than others when it comes to scoring!)

Step 2: Run Predictions for the Paths for Your Most Important QSOs

for this exercise. It can be downloaded for free at elbert.its.bldrdoc.gov/hf.html. There are several excellent

www.uwasa.fi/~jpe/voacap/ 21 writings at www.antennex.com, and my introductory tutorial at www.arrl.org/tis/info/pdf/Voacap.pdf.

VOACAP gives us the two necessary parameters that we need: the MUFday probability and the REL (short for Reliability) probability. The former indicates the probability (in terms of the number of days of the month) of having enough ionization to get RF from your QTH to your target area. The latter indicates the probability that the predicted SNR meets your selected criteria. but not to every place in the

Step 3 should help make this step clear.

Step 3: Be Flexible During the Contest

I cannot stress the following point enough } do not apply the band plan that comes out of and make changes on the fly.

The reason you need to be flexible is because the band plan was based on the model of  the ionosphere used in our propagation prediction software } it gives monthly median results. On any given day of the month, the next higher band could be better than the best

To help in this area, you should periodically check the next higher band. And use the NCDXF/IARU beacons on 20m through 10m to give a real-time assessment of these higher bands.

Example: A Multi-Single Effort from the Caribbean for CQWWCW This example will compare the process to a contest effort that already happened to see how well the process does. In 1997, K1TO, W5ASP, K9MK, and I did a multi-single effort in CQWW CW from ZF1A [note 2]. We ended up winning the World and setting a QHZ : to the old saying at all).

Since we were a multi-single entry, we had a decision to make as to what band the run station should be on for each hour of the contest. 

Being in the Caribbean meant our QSOs with the major ham population areas were worth different points. QSOs with North America were only worth 2 points, whereas QSOs with Europe and Japan were worth 3 points. Thus our most important QSOs were with Europe and Japan.

Should we therefore run predictions from ZF to Europe and Japan on all the bands? No } considered as bands to be on for a short period of time to pick up mults. So all we really though the smoothed sunspot number for November 1997 was 34 } miss any short duration openings. gives us the highest probability for the best score (3 pointers), not the best rate (2 pointers).

A comment about S 27dB in a 1Hz bandwidth (0dB SNR in a 500Hz bandwidth) as the input parameter to

VOACAP for our CW operation. For SSB, an SNR of 40dB in a 1Hz bandwidth (5dB SNR in a 3KHz bandwidth) is a good choice to input to VOACAP, and that gives around LQWHOOLJLELOLW\

antenna gains, try to be as accurate as possible with these values, especially over frequency with the Transmit antenna, as this will impact the results (through SNR). Figure 1 shows the MUFday and REL parameters, along with the product of those two parameters, from ZF to Europe and Japan on 40m through 10m for November 1997 [note 3]. The highest overall probability is shaded green for each hour, and this is what 

overall probability is shaded blue. Finally, 10m is shaded red. Figure 1 } Probabilities for ZF1A to EU and JA for CQWW CW 1997 UTC MUFday REL product MUFday REL product MUFday REL product MUFday REL product MUFday REL product MUFday REL product MUFday REL product MUFday REL product EU JA 40m 20m 15m 10 40m 20m 15m 10m close. For example, from 1300 to 1600 UTC, we should keep an eyH RQ P DV LW÷V QRW too far behind in probability to 20m } the day-to-day variability of the ionosphere could easily make 15m the preferred band during one or both days of the contest weekend. Similarly, we should keep an eye on 10m from 1300 to 1500 UTC } the likelihood of it openings to catch Qs and mults. mults. For example, in Figure 1 the overall probabilities of 40m to EU and 20m to JA at 2100 and 2300 UTC are close. 40m to EU would get the nod here.)

changes that ZF1A made. band, MHz highest 2nd highest 10m ZF1A Figure 2 } Comparison of the Process to ZF1A Band Changes Figure 2 is kind of busy, but what we would like to see is the black ZF1A line (the actual band changes) closely following the green bars (best band). As you can see, the agreement is pretty good when the comments about the second highest overall probability and 10m are factored in. And note that, indeed, the run station had excursions to 80m data in Figure 2 is for the first day of the contest. The second day was very similar, but with a bit more band changes to keep the rate up. 

Let me reiterate that this specific exercise compared the process to an effort that had already happened. In other word K1TO did the bulk of the run station work. He is very familiar with CQWW contests and statement that this process may not help everyone (an experienced contester operating from a familiar QTH in a familiar contest). -related factors that are important for contesting.

Get the Big Picture

Propagation Planning for DXpeditions.

azimuthal equidistant map) centered on your contest location. This will give you headings to the major contest population areas and to everywhere else in the world for multiplier hunting. It will also give you distances to your target areas, which could be important for short path / long path decisions. Finally, it gives you an indication of how high in latitude your paths to the major ham population areas go. This leads right into the

next section.

Understand The Impact of Disturbances to Propagation

There are three main categories of disturbances to propagation: geomagnetic field activity (designated as G in the NOAA scales), polar cap absorption events (designated as S in the NOAA Scales), and radio blackouts (designated as R in the NOAA Scales). For more information on the NOAA Scales, visit www.sec.noaa.gov/NOAAscales/. Geomagnetic field activity is caused by CMEs (Coronal Mass Ejections) and coronal holes and can result in degraded propagation at auroral latitudes and decreased F2 region

ionization at mid to high latitudes (and on some occasions geomagnetic field activity can increase low latitude F2 region ionization } see the September/October 2005 issue of NCJ for details on this). Geomagnetic field activity is generally the most detrimental to contesting, as the duration can be for many days. A good example of geomagnetic field details of this are in the Propagation column in the January/February 2003 issue of NCJ.

Another good example is what happened to 10m in CQ WPX CW 2002 } see the March 2003 issue of CQ magazine for these details.

A polar cap absorption event (called a PCA) is due to energetic protons from big solar flares causing increased absorption on those paths across the polar cap (the area inside the auroral oval). PCAs only occur on average at the rate of six per year. Thus for all intents and purposes the probability of a disruption to a contest by a PCA is quite low.
Radio blackouts are due to electromagnetic radiation at X-ray wavelengths (1 - 10 Angstroms) from big solar flares causing increased D region absorption on the daylight side of the Earth. Radio blackouts are generally of short duration, so their impact is not as severe as geomagnetic field activity. And due to absorption being inversely proportional to the square of the frequency, the higher bands will be affected last and will return to

ZF2RR operation in CQWW CW in 2000. The details of this are in the Propagation column in the September/October 2002 issue of NCJ.

Summary

:

(specifically VOACAP in this case) as the basis for a 3-step process to develop a band plan for contest categories that require a decision as to which band to be on at any given time. Although this process was intended for single-transmitter categories, it should work nicely for two-transmitter categories, too } the second highest overall probability would be for the second transmitter. a plan and change it than to never have had a plan at all. the output of Step 1 is determined.

Notes:

1. Our model of the ionosphere is a monthly median model, and as such it gives us monthly median results.

the myriad of factors that cause the ionosphere to vary on a day-to-day basis. More details on this

interesting subject are in the Propagation column in the August 2004 issue of WorldRadio.

2. You can read about this effort in the November/December 1998 issue of The National Contest Journal

(NCJ).

3. Note the many instances on 40m of a high MUFday value coupled with a low (or zero) REL value. All

this says is that there is enough ionization to get 7MHz RF from ZF to Europe and Japan, but absorption is

prohibitive. Also note the several instances (10m to Europe from 1300 to 1600 UTC, for example) of a low

MUFday value so low), the SNR should be great } with absorption inversely proportional to the square of

the frequency, this makes sense.