Amazing Reverse Beacon Network

I haven't called CQ for a long time on CW except in contests. Mostly I have just responded to DX calls with a super short "5nn TU" and that's it. But this Saturday I heard a presentation at the Norwegian Ham Meeting by Roland, SM6EAT about a Swedish initiative to increase CW activity. It is called Scandinavian Open CW Activity (SOCWA) and it has at present 452 members from Scandinavia in a wide sense of the word. It really got me interested in improving my CW skills.

So now I have started to call CQ SAX and have had my first long CW QSOs for years with SM and OH.

It is also amazing to look at the reverse beacon network and watch your own CQ being reported almost in real time from various Software Defined Receivers with CW Skimmers. Below is the result of the two CQs I have sent these two last days.

Overmodulated JT65 on HF?

Sometimes it is crowded on JT65 on HF due to too little bandwidth. When only 2 kHz is available and each signal needs 175 Hz that's understandable. But then others seem to complain that some overmodulate their transmitters so that they occupy more than the 175 Hz, making it even harder to fit an extra signal in the band.

As I have been running a lot of JT65 lately on HF, I also have seen this phenomenon and it piqued my interest to try to understand what was going on. The image below shows such a strong station to the very left, at about -1000 Hz where the red marker is located. After some seconds I turned on the attenuator of my K3, so the signal was attenuated by 10 dB (press image for zoom).

What one can see is that what appears initially (at the bottom of the waterfall) as a splattering signal, becomes quite fine when the attenuator is turned on. Then it spills into neighboring frequencies again as the attenuator is turned off again.

It appears then that it is the JT65 decoder software which is too sensitive to strong signals. Now, I cannot really say that I understand all of the decoder code, but I think that it has to do with the way the power spectrum is estimated. The FORTRAN code for ps.f is listed below. It comes from the BerliOS repository for WSJT which has the same code for this routine as JT65-HF-Comfort:

QOD7 - Can you communicate with me in Norwegian?

The Oseberg viking ship, 820 AD

Not so many nationalities are included in the exclusive group of countries with their own Q-code. I mean of course the QOD-code. I have never heard it used by radio amateurs, but it must have played a role some time ago in shipping.

The Q-codes date back to 1912 and were meant to be a short-hand for use in telegraphy. According to the list of Q-codes which Ralf D. Kloth (DL4TA) has on his web page, the meaning of QOD with a number added is: "Can you communicate with me in ... 0 Dutch, 1 English, 2 French, 3 German, 4 Greek, 5 Italian, 6 Japanese, 7 Norwegian, 8 Russian, 9 Spanish?" As a response to the question the meaning was "I can communicate with you in ..."

The reason for a separate code for Norwegian must be the historically large shipping fleet in Norway. This is still the case as graphically depicted in this overview of the Top 20 Ship Owning Countries, where we seem to rank as number seven - so QOD7 is appropriate!

But today all of them will QOD1.

Image from Wikipedia, user Karamell

Why do Norwegian callsigns end in A?

Well actually not all end in A, but almost all of the recent ones do. Amateur callsigns in Norway are not so well documented on the web, so here is a short explanation.

Norwegian callsigns are used in these territories:

• LA-LN for use in mainland Norway
• JW is used on Svalbard and close-by islands Hopen and Bjørnøya
• JX is used on Jan Mayen
• 3Y is used on Bouvet Island, Peter I Island, and in Antarctica (Queen Maud Land)

Depending on where I go, my callsign may be LA3ZA, JW3ZA, JX3ZA, or 3Y3ZA. We don't have districts so the number does not mean anything, except for 0. Callsigns with 0 are were reserved for non-Norwegian citizens, but this has stopped so LA0 callsigns are no longer issued.

Usually the callsign starts with LA, but why do so many of the LA callsigns end in A?

Long Delayed Echo on VOA Chinese Service

Thierry, F4EOB from Paris is still hearing strange echoes on the VOA Chinese service broadcasts. There isn't really any good explanation for this phenomenon.

Now during winter he is hearing it both on 13650 kHz from 9 to 12 UTC and on 21590 kHz from 9 to 11 UTC. The 21590 kHz transmission has been heard by him for a long time and I mentioned it here last year also. As then the echo is about 2 seconds. Thierry also made a youtube video of it with a recording.

The transmitter locations are in Asia. The 19 m band site is on the Mariana Island (Tinian) and the 13 m band transmitter is in Tinang in the Philipines.

In my blog last year I discussed possible explanations such as multiple transmitters or multiple round-the-world travel. But since the delay is so consistent and has had the same delay for such a long time, the probability that it is man-made is rather large.

Thierry tells me that this LDE can easily be heard with the WebSDR at the University of Twente in the Netherlands also. I would be curious to hear from people outside Europe who could compare the Dutch WebSDR with their own local reception and see if the same echoes are heard everywhere.

1 Volt/2 Volt Transceivers

Transceivers with a power supply of 1 and 2 Volts, how much can one achieve with that? Well, actually quite a lot according to DL2AVH, Helmut, who together with DL4ALJ, Gero, wrote two articles about that in the German QRP-Report in 2011. I am impressed by the output power, up to 200 mW with one battery cell (1.5 Volts) and 0.5 Watts with two cells.

I wrote about this in April last year where I also mentioned that the 1 Volt design from 2000 later had been corrected. Those corrections can be found in the article in QRP-Report 3/2011: "Niederspannungs-Schaltungstechnik - der 1-V- und der 2-V-transceiver" (Low voltage circuit technology - the 1 Volt and the 2 Volt transceivers). The improvements are concerned with better input filtering at 14 MHz with a quartz crystal in the front-end filter and better efficiency in the mixer and removal of an audio stage in the direct conversion receiver. This design only uses bipolar transistors and no ICs.

My grandfather's Blaupunkt radio

As I was clearing out my childhood home I came across an old radio that my father had tucked away in the basement. It was a German Blaupunkt radio, and what a historic dial it had!

It turned out that my father had himself found it as he was clearing out his childhood home many years before and that it had belonged to my grandfather who died in 1959.

It covers longwave, medium wave and three shortwave bands from 5.5 to 21 MHz. I had never before seen a radio with a dial given in meters rather than kHz or MHz, but I have later understood that that was not uncommon for pre world war II radios.

Since the back was missing, I had no information about age or type. The tubes which were all in the 11-series suggested the end of the thirties, but here it turned out that the dial had valuable information.

Twine "Internet of Things" Monitor

My children know what kind of gifts that please their father, so they gave me a Supermechanical Twine for Christmas. It is described in this way:

Want to monitor things and environments remotely without a nerd degree? Maybe you want to get a tweet when your laundry's done, an email when the basement floods, or a text message when you left the garage door open.

I am presently using it to monitor the temperature in the outer part of the basement, where there is a chance of freezing when the outside temperature drops below about -15 C (5 F). I can continuously read the status such as the temperature on any web browser on my computer or mobile phone. I can also set threshold values that trigger an email message.

The Twine is easy as a breeze to program, by using simple rules as shown below.