Tag Archives: Amateur Radio

RD Contest – State Scoring formula

Is the RD contest state score formula correct, and is it fair?
There has been a lot of concern about the RD contest state score formula, and conjecture about how it can be improved.
I have written this to clarify my thoughts and to show others what my analysis of the scoring formula reveals.

A fundamental principle is that the scoring formula has to work in the simplest of all situations, ie. when all states have equal performance.  We know the number of licencees is different so we cannot simply add up their logs and award the contest to the state with the biggest score.  That would give the result to the largest state and that’s not fair to the smaller ones.

To analyse the situation we have to start with some assumptions.

  • Assume all operators across all states had the same average points per log
  • Assume all states had the same participation ratio, ie. logs submitted divided by licencees

Should we expect that to result in equal scores?  Seems reasonable doesn’t it?

Let’s assume each log contains 10 points  (this can be an average, if you wish) and that the participation rate in each state is 10%.
Table 1. Examples of varying state sizes and scores
State Licencees Logs Participation rate (PR) Pointsper log Score(total points*PR)
A 3000 300 10% 10 3000*10%=300
B 1000 100 10% 10 1000*10%=100
C  200 20 10% 10 200*10%=20
We find that the smaller states cannot win if all operators score the same average points per log as the larger state.  Their population is a fraction of the bigger state and they need a correspondingly higher average points per log than the larger state does.
This simple example shows that the current scoring formula does not allow for different sized states.
In most RD contests, the two larger states have had low participation rates and several mid sized states have had better rates.  To examine how those scoring rates affect the outcomes, we can insert those factors into the model and see how that affects the state scores.
We can go further and examine what a smaller state needs to do in order to score higher than a larger one.

Table 2. Further examples showing how state score is affected by participation rate (PR)

State Licencees Logs Participation rate (PR) Points per log Score(total points * PR)
A 3000 150 5% 10 3000*5%=75
B 1000 200 10% 10 1000*100/1000=100
C 200 20 10% 50 1000*10%=100

Firstly, to explain States A and B of this example, the participation rate of state A has dropped to half its level in the first table.  But note that its computed state score has cut to a quarter of its original value.  It was 300 when its participation rate was 10% but with half the particpation the final score is 75, which is one quarter of the original value.  We can observe that the state score changes in proportion to the square of the participation rate.  Hold that thought.

This change in State A’s participation has had a dramatic effect on its final score, allowing state B to score better than state A, with the same average log value as state B.

Secondly, for the much smaller state C, I have illustrated how it can achieve the same score as one that is 5 times bigger.  Its logs contain five times as many points per log as the mid level state.  Here we can observe that the state score is proportional to the average points per log for each state, provided the participation rate remains constant.

Why is the state score not proportional to the Participation Rate?

As we know the formula for state score is:

State score = PR * (total of all logs)

However the total of all logs already reflects the participation rate, as if the PR were higher or lower, the log total would be correspondingly higher or lower.  Indeed if the number of logs was halved, the total score would halve.  Putting that another way:

Total of submitted logs = Total of all possible logs from state * PR

Rewriting the state score formula, we see that the state score formula can be rewritten as:

State score = (total of all possible logs from the state) * PR^2  (ie. PR squared)

From this it is apparent that the state score is proportional to PR squared.

This is why the state score is affected so dramatically by the participation rate PR.

How can the state score formula be improved?

Clearly the formula currently does not compensate for the different sizes of each state.
Teams of differing sizes can be compared only by normalising results to the average effort of each team member.  In the case of the states competing for the RD trophy, this translates to the average number of points earned by each state licencee.
ie. Average score per licencee = (Total points on logs) divided by (total licencees in that state).
With that formula, going back to table 1 above, the average score per licencee in each state is 1.0.  The average score per licencee in the other states is also 1.0.  A tie.
And since they both produced the same average effort per licencee, a tie is exactly correct. This measure works well for the case where all states perform equally.  How does it work if some states perform differently?
Let’s recalculate table 2, where states had different participation rates and different points per log.
Table 3. Sample results with Average Score per licencee
State Licencees Logs Participation rate (PR) Points per log Average Score per licencee
A 3000 150 5% 10 0.5
B 1000 200 20% 10 2.0
C 1000 220 22% 10 2.2
D 200 20 10% 50 5.0

Outcomes:

  • The anomalous  results shown in Table 2 have gone.
  • State A: large state, low participation, logs submitted are average value, overall rating 0.5.
  • State B: medium size state with higher participation than state A, and a much higher score – 2.0.
  • State C: like state B but with 10% more logs.  Note that the score is 10% higher.
  • State D: the exaggerated example of a small state with very high average logs, scores best of all at 5.0.

As can be seen the results are linear, with increased scores resulting in a proportional increase in State score.

Where to from here?

The state score formula should be changed to the following:

State score = (total points from logs submitted) divided by (number of licencees in the state) [see note below]

I would like to see this analysis considered by contest managers and other decision makers within the WIA.  I believe that the state scoring formula was fundamentally flawed because it was based on incorrect mathematics.

It is recommended that this part of the contest rules be corrected at a suitable time, to reflect the results of this analysis. It may be too late for the rules to be changed for 2012, but perhaps this anomaly can be corrected for subsequent years.

This change would make it more feasible for the contest to be won by different states.  I believe the run of wins for VK6 has occurred due to good promotion of the contest in VK6 combined with a severe penalty for the larger states imposed by the erroneous formula discussed here.  I feel sure that with a more appropriate formula, competition would be enlivened and the contest would be a healthier and better supported event.


Note: number of licencees is adjusted to remove licencees that cannot participate in contests such as repeaters and beacons.  This is already catered for by current rules, but I did not wish to complicate the description above.

Reference:  Current rules for the RD Contest, rule 14.1 defines the state score calculation. http://www.wia.org.au/members/contests/rdcontest/documents/RDcontest2012Rules.pdf

QRP Hours contest 2011

This is a short contest for QRP operators.  It runs for one hour on CW mode, then 1 hour on SSB.  A truly easy contest to participate in.  All licence classes can participate as QRP (low power) or their ordinary power.  The contest was sponsored by the CW operators QRP club.

I wasn’t sure I would have an opportunity to operate in this contest but at about 6:30pm on Saturday 2nd April I decided I should put up an 80m antenna and have a go.  At 6:40 I had identified a two section telomast and was measuring out some guy ropes for it.  Having found some stakes, guying ring and found the wire antenna cross-boom with the attached halyards and pulleys, I was able to assemble the mast, attach the cross-boom, lay out the guy ropes and do a trial setup to get the guys set to the right lengths.  Once that was done I hammered in three stakes and attached the guy ropes to two of them.  Walking the mast up to vertical showed I had set one guy at an impossibly long length so it all had to come down.  Next time was ok so I could walk the third guy out to the stake and tie it off.  One 20 ft feedpoint suspender ready for action. Time about 7:15.

I had a 80/40m dipole assembly last used two years ago at a rental property in Canberra.  I attached the centre conductor to one of the halyards and hauled it up to the dizzy 20ft height of the mast.  Then I attached some light cords to the antenna ends and tied it to the fence at one end, and to some ground stakes at the other end of both dipole wires.  This work was completed in the dark as the sun set at about 6pm local time.

The two dipoles are joined at the centre.  This works because the 80m antenna is a very high impedance on 40m, so is virtually “not there at all”. The 40m dipole detunes the 80m one slightly but I went through the adjustment process with this antenna about 20 years ago and have simply rolled it up when I finished using it each time.

Then I got out the FT817 and found a suitable keyer cable, microphone, power supply.  On 80m the dipole presented a 1:1 match on the CW end of the band so that was fine.  On 3690 it was about 1.3 but my Emtron tuner handled that mismatch with a fairly broad dip.  The time now was about 19:45 local and the contest started in 15 minutes, or so I thought.

At 20:00 local time I heard a station calling CQ TEST so I answered, received a number, gave a number, signed off.  Good start to the contest, I thought. Then I called CQ TEST myself.  No replies.  Tuning around showed nil activity.  Called CQ again.  This time I got a reply from an operator who kindly advised me that the contest was not due to start until 2100 local time.  I opened up the computer and checked the contest rules.  Start time 1000 UTC, which was 9pm local, but somehow I had reverted to non DST in my calculations due to daylight saving ending later that night.  1000 UTC was almost an hour away.  So I had time for some dinner!

About 45 minutes later I went back to the radio and started the contest again at the right time.  Signals were strong and most stations were in the vk2, 3 and 4 areas though there were some vk5, vk7 and ZL stations worked too at signal reports of 559 or so.  I made 10 cw contacts in this hour.  A slow contest compared with the DX contests but it was also quite relaxed and unrushed.

At 1100 UTC the SSB section commenced, operating between 3550 and 3590. Signals were very strong from some stations.  Again a few names were exchanged as well as the contest numbers.  15 contacts on SSB, and I got the impression the antenna was working well, as mostly my replies were answered after only one call.  Quite good for a 5 watt signal.

I have sent in my log and I don’t think this is the only QRP event I will operate in.  This was a very enjoyable process and quite rewarding for the minimal effort required to get on the air.  Next time: antenna up another 10 feet.  And the ends should be higher too!  Should be no problem.  I might even do most of the work in the daylight next time.

Mast and 80/40m dipoles
Mast and 80/40m dipoles
Feedpoint of 80/40m dipole
Feedpoint of 80/40m dipole

VK9NA expedition

Late comments about the VK9NA expedition I joined in January 2011.  This was a VHF/UHF/microwave and 2m EME operation.  Due to quite poor conditions for tropo across to the mainland, we eventually did most of the operation on 2m EME.  However we did try to make contacts and ran a lot of CQs on 144 MHz every day.  We did make some contacts but there were nowhere near the number of tropo contacts made last year.  The 144 MHz band was the main band used for this work.

We activated the station every day on 6m as well, from the hotel site.

Due to the high winds experienced on the hill we moved the EME station to the Guide Hall where we had been kindly offered the use of the grounds.

On Norfolk the internet access is provided by Wifi connections at hotels/resorts and a few in the Burnt Pine business area. I found it was necessary to buy several different cards to get access via NIDS, Norfolk telecom and another account for access at the hotel I stayed at. Wifi access from Mt Pitt was good, from the hotel the others stayed at, access to NIDS was not good.

The radio conditions on vhf up were not as good as they had been in 2010. This was partly due to physical weather conditions, including strong winds for the duration of the operation from 8th to 20th January. On the weekend of the summer field day conditions were very poor and the only contacts made with the mainland that weekend were on 6m, and there were not many of them.

The 2m EME operation was very successful.  Over a hundred contacts were made using JT65 via the FT897 and a laptop computer running the WSJT software.  A TE systems amplifier boosted the output power of the FT897 for EME work.  The list of stations worked is at the VK9NA website.

I greatly enjoyed the event.  I learned how to use WSJT on both FSK441 and JT65B, and learned a bit about pointing a very large 2m antenna (19 elements, 12 metres length) at the moon and periodically repointing it. For about half or more of the time, the moon was not visible so we were relying on compass bearings corrected for mag offset/declination and an inclinometer for the elevation.

I also became familiar with the FT897 and found what a great radio it is for this kind of operation. The other radios used were FT817 and a TS2000 which I found to be a very good radio too.

The TS2000 has an option to automatically transmit CW at a 700 hz offset (actually the offset equals your selected cw beat note and sidetone frequency) when you switch from USB to CW. It also has an option to automatically switch from SSB to CW mode if you press the key, whether it’s an automatic key or a hand key. Very neat.

Apart from the radio aspects it was also great to get to know Michael VK3KH, Alan VK3XPD, Kevin VK4UH. We were fortunate in being well organised on the social and meals front by Michael’s wife Roz and her sister Gail, and Alan’s wife Aileen all of whom made this event that much more enjoyable.

We did attend a few local special events such as the fish fry, the progressive dinner and the re-enactment drama based on the voyage of the Bounty, the eventual mutiny led by Fletcher Christian and the exile of the mutineers at Pitcairn Island. This history is a proud aspect of the Norfolk Island culture today.

A great event and a fun filled 10 day trip for me.

Here are some photos at Flickr:

Here is one photo of the EME antenna.  Remember  it is 12 metres long.  There are 19 elements.  Click the photo for a larger view. The long “element” in the centre of the boom is just a truss boom – the antenna has vertical and horizontal stabilisation to prevent it flexing and losing gain. EME antenna at VK9NA

2010 Spring VHF/UHF Field day on 7 bands

For this event I took my usual station on 50 to 1296 MHz, plus my transverter and gridpack for 2403 MHz, Ted VK1BL’s transverter and gridpack for 3400 and Dale VK1DSH’s 10 GHz station (IC202, transverter, dish and tripod).

Contacts were made on all these bands.

Performance of the station on 1296 MHz was not as good as in previous years.  This may be due to conditions, or to a problem with my antenna or my location on Mt Ginini.  It is becoming increasingly more difficult to find suitable places where even two required directions are not partly blocked by the trees on that mountain.

Some pictures are already on http://www.flickr.com/photos/exposite/sets and I’ll be putting some also onto the vk1da.net photo pages.

Joining VK9NA VHF/UHF dxpedition to Norfolk Island

I am joining the VK9NA team for January 2011. All the details of this expedition are on the VK9NA.COM website. This is a VHF/UHF/microwave expedition which will include some 2m EME capability and will have reasonable power (75w) on 5.7 and 10 GHz too.

The station should be on the air by 9th January and will be active in the following weekend’s VK VHF/UHF Summer Field Day event.

More details on the VK9NA website vk9na.com

Dayton Hamvention trip 2010

After reading about the Dayton Hamvention for over 30 years I decided this year I should see it for myself.

Well it is a big show.  Very big.  Have a look at the Hamvention website and you’ll find maps of the covered exhibition areas and the flea market area which is described as being 9 acres.  I observed that some lanes of what is normally a car park were not fully occupied, and some discussion on the hamvention mailing list (see yahoo groups) indicated that there were many more vendors in the flea market area in past years.

There were over 200 vendors in the covered areas.  The Dayton Amateur Radio Association (DARA) conducted exams for those who wanted to take out a ham licence, or upgrade from Technician or General to a higher grade. Candidates were lined up outside the examination areas all day, Friday and Saturday.  Hundreds must have been examined.

All the equipment manufacturers you have heard of and a lot you haven’t were present with impressive displays of their wares.

New to me were the Kenwood TS590 (HF/6m 100w transceiver), the Flex 1500 (HF/6m 5w transceiver) and the Elecraft 500w power amplifier.

I also saw a rotary 80m dipole on display from Array Solutions.  It looked to be about 50ft or 15m long, with loading coils and loading sections on each end of the dipole. It may have been shorter.

In the flea market there were many hundred vintage radios, ATUs, cables, antennas, connectors, you name it.  My vote for the most unusual item was the F16 simulator.

I came close to buying several new items but eventually just picked up some small components I want for my new antennas, some microwave attenuators and a G4DDK preamp kit for 2.4 GHz.

I met G4DDK at stand 915 where he and Kent WA5VJB were displaying and selling various items including a range of Kent’s pcb antennas including log periodic and skeleton horns for frequencies from 400 MHz to 10 GHz.

The event wound up officially at about 1pm on Sunday.  After that the exhibitor’s area was closed.

I missed out on a great deal I had been offered on an SDR-IQ receiver on Saturday afternoon.  I didn’t realise how many vendors would either close early on Sunday or not turn up at all.  I’ve emailed RF Space and have received a reply already, so all may not be lost.

Dayton Hamvention: well worth going and seeing it, but only if you already have a reason to go to the US.  It’s a long way for 2.5 days of hamfest.

At the VHF weak signal group dinner on Friday night, I met and chatted with a number of other people about VHF activities in Australia and heard discussions on contest rules that were familiar issues.  Should contest points be based on distance or on grid squares, or power, or what?  In the VHF sprints they are trying a distance based formula based on 6 character grid locators.  They have found that this approach has been well accepted by contest participants.  It is now quite feasible to calculate distances based on 6 character locators, since computers are so common.  Maybe this is what Australian VHF operators would like.  The grid square bonus system is much simpler but some people think it doesn’t give recognition or incentives for longer distance contacts.