propagation measurements

Home 29-3 t/m 30-4

In March 2018 I started an experiment to measure the QRP NVIS beacon on 80 meter band from PA0RYL

Some data of the beacon

frequency 3555.555 kHz
 10 mWatt output
Antenna Full size 80 mtr loop



I wanted to measure the signal to noise ratio and tried to search for ways to get this done.

I found some software from G4JNT for this but after a while I found that with the very low S/N ratio
from the beacon this was not good enough for my purpose.

I was using a Perseus receiver for receiving the beacon and I found the function Mkrlog which generates a logfile of the selected markers.
At first I tried to see how this would work but at that time I never could find the log file created by Perseus.
I tried it several times and the way Perseus software responded seemed normal to me as if all was working fine.
I decided to let my computer do a file search for the marker.log file and after some time it found the file in a hidden directory,
so that was the reason why I could not find it before.

With the marker.log file I have the measurements from the beacon available.

I have put a marker on the beacon, and a few markers around the signal to measure the noise level.

The data is then used in Excel to create a graphic picture of my measurements.
It took me a few days to find the best way to use Excel and create a clear picture of the measured results.

I measure each 5 seconds the power level received at 3 different frequencies,
first is the beacon frequency and then two ore more close by the beacon to measure the noise level.

During a 24 hour period I make 17.280 measurements.

The beacon on my Perseus screen


The receive antenna is at my home QTH in Haselunne, Germany; locator JO32sq

For receive I use an partial home made active loop antenna,
the loop with 1 meter diameter is made from a Wico copper tube with a weather proof coating

The amplifier is designed and build by LZ1AQ :

I started the measurements using a Resolution Bandwidth of 1 Hz, later I increased this to 1,9 Hz because the beacon fell of the marker, probably my receiver frequency drifted due to temperature drift. Some days after I decreased it to 0,5 Hz, the lowest RBW that can be selected in the Perseus software I use.
Since then the measurements went well. The lower the RBW the lower the noise floor will be giving a better performance.
I found that many amateurs use the frequency of the beacon or close by and a smaller RBW improves the interference rejection also.

If you read this, please do not transmit on the frequency of the beacon because it will influence the measurements.  

The first result looked like this, it is a measurement from 27-3-2018 from 18 UTC until 21.36 UTC

The same measurement but then with small dot's


Here I added a trendline, giving an average of 100 measurements


This will be the format how I want to publish my measuring results

For the results of my measurements take a look at the page: 29-3 t/m 30-4