My MEPT to ZL land through short and long path

Today was very special for my tests. This morning Peter ZL2IK from Northland, New Zealand, sent me a reception report through the QRSS Knights Mailing List and he was writing the following:

“Hi Knights and George

Within the last 24 hours I have received George SV8GXC on the Long Path, via the Atlantic and Pacific Oceans, and on the Short Path via the Middle East/Indian Ocean/and Australia. See attached grabs, taken overnight my time…”

Long path from SV to ZL


Short path from SV to ZL

With the help of DX Atlas software (by Alex VE3NEA), I was able to calculate the actual distance between my grid locator (KM17uw) and Peter’s ZL2IK grid locator (RF74ci). The distances for short and long paths are 17376km and 22628km. Based on the facts that my MEPT’s transmitting power is only 160mW and that ZL2IK is my longest DX, Peter’s new long path reception increased my personal KPW (Km Per Watt) score from 108600 KPW to 141425 KPW. Thanks Peter!

SP and LP distances on DX Atlas

References:
[1] SV8GXC, My 30m QRPp MEPT, http://sv8gxc.blogspot.com/2010/09/my-30m-qrpp-mept.html
[2] QRSS Knights, Mailing List, http://cnts.be/mailman/listinfo/knightsqrss_cnts.be
[3] VE3NEA, DX Atlas Software, http://www.dxatlas.com/DxAtlas

Miles Per Watt in QRP

Miles Per Watt or MPW is a term very well known to QRP operators. MPW is a calculated value based on the transmitted power that was used on a single or two-way communication and the distance that was covered between the two parties. When we say one-way communication we mean the reception of a beacon and two-way we mean the QSO between two radio amateurs where each one has the capability of transmission and reception. MPW is used as unit for the measurement of the quality/importance of a communication from the transmitting power point of view.

The only things we need to calculate MPW is the distance between the transmitting and receiving location and the transmission power. The calculation of distance is a little bit complex and can be done if we know the geographical coordinates or the grid locators of the two locations. Assuming we know the distance the MPW can be calculated with the following formula:

Miles Per Watt (MPW) = Distance (Miles) / Transmission Power (Watts)

Just because the calculation of the distance based on geographical coordinates is difficult, web based WPM calculators are available online. The most popular is the "N9SSA Distance and MPW Calculator".

In this calculator you may enter latitude and longitude or the grid locator of each location and the power in Watts, you click the "Calculate Distance" button and you have all you need: Distance in Miles, Miles per Watt, Distance in Kilometers and Kilometers per Watt.

Reference:
[1] N9SSA, Notes N9SSA's Miles Per Watt Calculator, http://www.hoffswell.com/n9ssa/mpwnotes.html