06 February 2014

WSPR 'ing Fun: 411.200 km with One Watt

I have to admit, that the title is not quite right! I would not get a signal report from a man sitting about 26.000 km behind the moon. There is in the moment nobody who could listen to my signal.
It was OH8GKP Heikki listening to my call and he lives about 2056 km from my place. And I was only using 5 mW. And if I did my math right I have to multiply 2056 with 200 (1000 mW (1 Watt) / 5 mW).

But we will make it slowly and here you will see my results with my 5 mW of this morning taken from wsprnet.org.

The Map from WSPRNET.ORG with search: "dl1sdz"

To encourage people to experiment with low power I will show you, that you don't need to have a super station or big computers to reach other parts ovf the world with flea power.

My System

As told several times I use in the moment an Ultimate 3
Display of the Ultimate 3 (Sorry for the bad photo)

with two High Power Transistors  BC107 ;-) (They cost about 0,30 Euro a piece. These both produce on 30 m a signal meassured on my scope of about 9,7 Vpp ( ~200 mW  or - 23 dB).

Next comes the important part: I would not be able to measure power accurately under 100 mW although I use the QRPOMeter for output > 1 Watt or as a dummy load.

QRPoMeter from the 4sQRP-Group

So it is high time for the 41 dB RF Step Attenuator, a kit produced by Dirk Hendriks.

This Attenuator works like very precise.

So I do not have to control the output of the Ultimate 3. It produces constantly 200 mW = 23 dB. When I want to transmit with 5 mW, I push the sliders

  1. from Bypass to ATTN.
  2. 1 dB on
  3. 2 dB on
  4. 3 dB on
  5. 10 dB on
So I have an attenuation of 16 dB. 23 - 16 = 7 dB = 5 mW. Well done!

Next important thing: My antenna is not tuned to 10 MHz. So I switch a antenna tuner in line. I use an Elecraft T1, which is my standard tuner since many a year. (I have to tune it with another rig, for the tuner needs 1 Watt.)

I use an Unun Balun and 8 meters of wire filed through two trees in about 6 m over ground. (This was not an easy task.) When you read carefully, you will notice that this is not a real antenna, it is not even an antenna compromise. It is just a random wire which works. I am all of the time really astonished, that my signals get noticed.

And when I add up, without convenience devices like the T1, which could be replaced by some parts for 5 Euro, the whole system costs about 100 Euro + Internet access for getting the reports.

And here are some results of the last days:

  • 200 mW  VK6XT    14049 km  =  70.245     km / Watt  
  • 100 mW  VK7TW   16756 km  = 167.569,5 km / Watt
  • 50   mW  W3HH        7721 km  = 154.420    km / Watt
  • 10   mW  LA9JO        2342 km  = 234.300    km / Watt
  •   5   mW  OH8GKP    2056 km =  411.200    km / Watt
Don't get me wrong. It is not about having the biggest, longest, most costly thing. I am talking about a "wonder". I am using a signal with a strength that would have to be amplified 12000 times to light a normal light bulb with 60 watt and I get heard on the other end of the world.

What is the secret that makes this "miracle" possible?

1. Devoted People
This is the most important factor. Without the help of countless other hams, who spend their time and money for free to achieve a global net of interest and dedication I would sit in my room and would look out of the window. They developed the circuits, made the software development, sorted and delivered thousands of parts to enable other radio amateurs with less skill to build the kits. Others make their equipment available to others by monitor signals all over the world and make these data accessible in internet databases.

2. Advanced Technic
The protocol of WSPR was developed by K1JT (John Taylor). He developed WSJT, MAP65, WSPR, and WSJT-X and declared them as open-source programs designed for weak-signal digital communication by amateur radio. Without this Technic it would not be possible to decode signals which are 30 dB under the noise level. You just would not hear it in your radio. 
And there are countless programmers who implemented these algorithms in little processors (again in my case Hans Summers)

3. Nature
And of course don't forget the Earth, the Moon and the Sun who provide these layers so that radio waves could find their way around the Earth.


Yesterday evening a friend asked me: "What does this have to do with amateur radio? Normally I sit before my radio and turn the dial. There is a hiss and suddenly you will hear the sound of morse code. I grab my keyer and off I go into a two way communication. What you are doing there: You just send some signals into the air." Later he admitted, that he has been off the air since a couple of years due to only 599-QSOs in contests and the silence on the bands during the rest of the time.

So he expressed also my absence on the bands. It was boring and cost a lot of time finding another om, who was willing to do a longer chat.

On the other hand with Wspr, I got
  • two way communication via the reports
  • two way communication with dedicated and friendly radio amateurs in discussions about technical aspects of software, hardware and handling in various forums
  • a tool for analyzing my antenna and actual propagation
  • technical expertise about modern digital transmission systems
  • hands-on expertise while soldering and debugging my equipment
  • ...
And that's a lot considering the actual costs.

My advice: Turn down the signal and try for yourself. You will be astonished what is possible even with signals below the noise.

Stay Tuned!