Optimal tx fraction

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Joined: 2009/06/08 - 21:30
Optimal tx fraction

My proposition is that more logged spots enables more inference from the data.

In looking at reasons why I get so few spots, I have explored amongst other things, the effect of tx fraction or tx duty cycle.

Obviously, if one station transmits more often, one expects more spots... but if we all transmit all the time, there will be no spots.

One of the effects I observe on 40m is that for some hours of the day, local propagation is so good that local stations transmitting on WSPR degrade my receiver sufficiently that I do not hear distant stations in the same interval.

So, I have built a probability model for a large number of stations assuming equal station capability and good propagation, and the expected number of spots per hour (per station) with no local 'interference' (being degradation due to local WSPR stations), and 1, 2 , 3 interferers.

The plot is at http://vk1od.net/lost/Clip%20211.png .

My own environment has led me to trial 34% tx duty cycle (tx fraction) to explore the outcome.

The combination of raising power from 5W to 20W and increasing tx duty cycle from 20% to 34% has dramatically increased reports of my transmissions without significantly decreasing reports I have made.

I will run WSPR on 40m from 00:00UT on Saturday 30/7/11 to assess the behaviour on a busier weekend day.