6 m WSPR analysis for Roger G3XBM

In his informative Blog, Roger G3XBM wrote about aircraft scattering of signals on 6 m.
I had the pleasure of making an analysis of the WSPR spots reported by Roger.

Drift
In WSPR the drift is measured over a period of 1 minute, so the drift is given in Hz per minute.
Recently I included Drift in my Excel spread sheet that I use to make an analysis.

Analysis

• The value in the table, such as  -4, is a spot with a drift of -4 Hz per minute.
  Positive drift means that the radio path is getting shorter and negative is longer.
• The signals of M0MVB show spots with a drift of -2 and   3 Hz per minute.
  It is possible, that there is a flight paths involved in the spots with -2 and an other path with the spots of   3 Hz per minute.
• The scattered signals with drift, sent by M0YOU are very strong, with a lowest possible power of 1 mW. The spot with no drift (0 Hz per minute) has a lowest possible power of 50 mW, thus is 17 dB weaker.
• The signals of M0EMM show no drift. So it's possible that there is no airplane scatter here, but an other form of propagation, such as difraction. Notice that all these spots are made within one hour.

Thanks to Roger. FB.

A few day ago I wrote to Roger: See article
Hello Roger, 
This evening I took some time to make an analysis of a number of spots on 6 meter.
I took the most interesting spots for airplane scatter.
I hope you like it and can place it in your blog. 
I left in M0EMM to show the difference. hi
Positive drift means the path is becoming shorter. 

The spots of M0MVB shows spots where the path is becoming shorter (+3Hz per minute)
and spots where the path is becoming longer.   (-2 Hz per minute)
I just saw that the spots of M0YOU with scatter, are much stronger than the spot without scatter. 
The lower the lowest possible power, the stronger the signal.  
A lowest possible power of 1 mW is 17 dB stronger than 50 mW. hi.
I left in the spots of M0EMM, to show that there is no Doppler and the signals are not that strong.

Good luck in further analysis,
73, Bert PA1B

WSPR Propagation Analysis - G3XBM 28 MHz Dec 2014 (2)

The propagation changes from day to day, as you can read in the blog of Roger G3XBM.

Here is an analysis of the WSPR spots of G3XBM that were received by K9AN 
on the 24th and the 28th of December 2014.  
The time is given in UTC.

The diagrams show a lot of spots, since K9AN listens every two minutes. hi

The lower the calculated lowest possible power, the better the propagation.

On the 24th, the propagation is at it's best around 13:50 UTC and 17:06 UTC,
with a calculated lowest possible power of 5 milliwatts.

 Click to enlarge.     G3XBM  received by  K9AN  on  2014-12-24

On the 28th the propagation has a short peak at 14:52 UTC.

Around that time there are seven successive spots, every two minutes.

In the spot of 16:36 utc, the full power of 500 mW is needed, to be spot. hi. 

G3XBM received by K9AN  on   2014-12-28

In most of the spots, the calculated lowest possible power is 50 mW or less, on both days.

This means that, if you would use CW instead of WSPR, that 1 watt (20 * 50 mW) could be used to make QSO's in CW.

WSPR Propagation Analysis - G3XBM 28 MHz Dec 2014

Roger G3XBM ran his WSPR signal for several days on 28 MHz.
This provides interesting information on propagation on 28 MHz.
I collected data from the WSPR database, to make the diagrams.

The first two diagrams, show spots that are collected over several days.
The strongest spots are given in red. 

The first two diagrams show the calculated electrical field strength in micro volt per meter.
If spots show the same field strength, the voltage on the antenna will be the same, for a simple wire antenna.
The difference between the successive values of the field strength is 5 dB.
This is about one S-point, since 6 dB is one S-point. 
The lower the value, the better the propagation.
So 0.03 micro volt/meter is about 1 S-point stronger than 0.06 micro volt/meter.

The strongest spot over 900 km was 2 S-points down, compared to the spot over 5300 km

The strongest (in red) spots show the same field strength.

Notice that the spots over 5300, 6500 and 14700 km were made with the same field strength at the receiving antenna, so the strength of the signal that arrived on the antenna  was the same in these three spots.

Further analysis shows which receiving stations have Excellent Ears. See the spots in red.
The spots in red in the table below correspond to the spots in red in the tables above.

The stations with excellent ears.

Power in CW
I was wondering, how much power would be needed to make  CW QSO's.
For a CW QSO you need  twenty times more power,  (Click) than for a WSPR spot. (13 dB)
The diagram below shows the  Calculated lowest possible power  (Click)in milliwatt for each spot.

For the strongest WSPR signal, received by K9AN the calculated lowest possible power is 2 mW.
Thsi means that the that 2 mW would be received with a SNR of -29 dB. (Solid copy in WSPR)
To be received in CW, a power of 20 * 2 = 40 mW would be needed.
This does not surprise me a bit, since I made a CW contest QSO with K3WW on 21 MHz in 2012 with 36 mW.

Rogers signal was also heard in VK. The calculated lowest possible power was 5 mW.
So in CW his signal would be heard with 20 * 5 = 100 mW.
This seem too low, but please notice that to double the distance it takes an increase of 1 S-point (6 dB) to get the same field strength.
One  S-point means four times more power.
Further, please notice that WSPR is patient and tireless.
It is even possible that one of the operators was a sleep during the time that the spot was made. hi.

WSPR Propagation Analysis - G3XBM 28 MHz

Many WSPR operators jump from one band to the next, when band conditions changes.
Roger G3XBM ran his WSPR signal for several days on 28 MHz.
This provides interesting information on propagation on 28 MHz.
I collected data from the WSPR database, to make this diagram.

In this diagram, I choose to show the spots of Roger received by DK6UG over 600 kilometer and LB9YE over 1500 km.
The diagram shows the number of spots for a day and from hour to hour.
The stronger the signal, the lower the calculated lowest possible power.

DK6UG over 600 km
It's interesting to see that the propagation to DK6UG changes from day to day.
On the 13th there are two peaks in the propagation, with no propagation in between.
On the 14th there is only a spot on 18 UTC.
This is at the same time of the peak of the day before.
On the 15th there are 3 peaks at 11, 14 and 19 UTC
The 17th is the most interesting day.
The day starts with reception on 11 till 12:58 UTC.
The 17th shows one very strong spot at 14:10 UTC with a calculated lowest possible power of 10 mW. The next spot with a CLPP of 1000 mW was on 14:54 UTC. Notice that in this spot the signal strenght is 20 dB lower.
Please notice that there is no reception from 13:00 till 13:58 UTC on all days,except for the 19th.

LB9YE over 1500 km versus DK6UG over 600 km
Most interesting are 13th and 14th
At the 13th the propagation is good to DK6UG, but not to LB9YE.
At the 14th it's the other way around.

"WSPR Propagation Analysis" for WSPR spots of G3XBM on 10 m

Roger, G3XBM wrote:
Nothing at all was seen until mid-afternoon and then the band just opened wide!  
K9AN (6505km) last spotted my 2W signal at 2308z, which is after midnight local time and HOURS after the band has normally died out. It had been dark for hours. One wonders if this was F2 or even multi-hop Es? I wonder what was happening on 6m transatlantic?  I must check.
(Spots made on 2014-04-08) Click to visit the article.

I was interested, so I made an WSPR Propagation Analysis of the spots on that day and the days before. The second table shows the last spot at 23:08 UTC, but also reveals the rapid change in propagation around 22:20 UTC.

How to read the table 
In the analysis above, I show the "Calculated Lowest possible Power" in milliwatt and the hours of the day in UTC. The lower the "Calculated Lowest Possible Power", the better the propagation.

To compare the propagation over several days, 

I included 2014-03-28 till 2014-04-08.


Roger is refering to WSPR spots made on 2014-04-08.
At the bottom of the table above.
From 10 UTC to 22 UTC the propagation gets better.
The best propagation occurred in the spot with the red star made on 22:20 UTC.



Even more spectacular
The best propagation on 2014-03-28, at the top of the table, occurred between 13:00 and 15:59 UTC in the aftenoon.
But even more spectacular is the change in propagation in the 3 spots * that were made between 22:00 and 22:22 UTC, that show a very rapid chang in propagation. (See the red arrows)

Thanks to Roger for the interesting experiments with WSPR.

Analysis of G3XBM's 40m WSPR spots with 5 mW

G3XBM left WSPR running with 5 mW on 40m for 24 hours.
Roger concluded that his signal was in the noise most  of the time.
He also concluded that he would need 2 W.
http://g3xbm-qrp.blogspot.nl/2014/01/40m-5mw-summary.html
The analysis below shows that the conditions changed dramaticly after the 7 spots with 5 mW.

The header of the table shows the Calculated  Lowest Possible Power in mW (Click for info), 
which is calculated from the used power (Pwr Sent  in mW) and the SNR.

The better the propagation, higher the SNR and

the lower the Calculated Lowest Possible Power will be.

The analysis
9 UTC gives the spots that were made in the hour from 9:00 till 9:59 utc.

This first line shows, that the power that was needed for the spots was 1 W down to 2 mW

In this hour, half of the spots that were made with 2 W could be made with 100 mW.

The white circles indicate the power with which half of the spots could be made.

The lower the power needed, the better the propagation.

From 9 utc till 14 utc on the 18th there are 11 spots with a calculated lowest possible power of 5 mW or less. So it was possible to make spots with 5 mW.

WSPR with 5 mW
From 14 utc Roger reduces further to 5 mW and over 24 hours only 7 spots were made, shown in the yellow coloured part of the table. In the red part of the table there are no spots since the power that was used is 5 mW. In the red part I show the receiving stations and their SNR.

Back to 2 W
You would expect more spots, since the 24 hours before showed many more spots that could have been made with 5 mW. But the conditions changed dramaticly.
The last part of the table shows spots that were made with 2 W.
At 20 utc on the 20th at least 500 mW is needed.
And at 5 utc and 7 utc spots could have been made made 5mW