i have a (Ham) Amature radio type question
 

I am listening on shortwave tonight and i heard something i don't hear very often. Morse code over Am modulation. Its a AM broadcast somewhere around 5900 Khz using a 1khz tone to transmit code. Why would someone do this? its very wasteful on power. It would be better just to send switched CW. Unfortunately i can't copy code to see what they are sending. but they have been transmitting for over a 40 mins now. Logan

Hello,

This could be some kind of 'Numbers station', although they generally use
voice rather than Morse code. See this link and keep on listening:

http://en.wikipedia.org/wiki/Numbers_station

Maybe they are using AM because this easier to use for the intended
target. Any other ideas?

It's called MCW, for "modulated continuous wave". The advantage is that an ordinary AM receiver with no BFO can hear it easily.

John

Ya know, that makes sense. I've heard countless "numbers stations" but this is the first MCW station I've heard, and since i can't copy code, it never dawned that they could be sending numbers. Wow you'd think there would be easier ways for spies to talk to each other than dah dit dah etc.

Those dits and dahs are much easier to copy than speech during severe noise conditions. Ham radio in the past was often the mode of emergency communication during stormy weather when telephone had conked out. Lightning crashes from thunderstorms can make speech very difficult to impossible to copy. Tornadoes produce a hash that can render communication by speech out of the question. The dits and dahs can often get through the natural interference (qrn; atmospherics) when speech cannot.

well I understand the advantages of regular code over voice, but i was thinking to having to copy the numbers down, then feed them into a one time pad to get the final message, i'd think today, it would be more effective to have a digitally encrypted device that looks like a common personal possession, cell phone, blackberry ipod etc. Heck you could even use a GPS receiver. I dunno but having sheets of code paper seems like a greater security risk than finding what looks like a cell phone. Just my ramblings, Logan

Well other people are feeling the same way, because you can get a ham license without having to learn code.

And, instead of emergency situations (which can be handled very well through cellphone use in most situations) and tech talk, today's topics appear to embrace the failing human body, meds and not being able to pee. All the hams of old are now coming of age....

Please don't get me wrong, I 100% support the concept of HAM radio. If I was elected Grand Poomba of the World, I'd pass a law requiring all HAM bands to be in existence forever, and prohibiting any interference with their operation. It only takes a earthquake, typhoon, tsunami, major solar flare etc to render a region back to the dark ages. Then the only way of communicating is by Ham radio, I'm sure there are plenty of hams who could assemble a transmitter out of parts laying around in their parts bin within a few days if necessary.
I just wish "Spies, OTH radar, and that weird swishy sound around the 5 mhz WWV" would leave the shortwave bands alone.

Actually I wouldn't expect it to be a numbers station using MCW. I dont know for sure, but I'll bet it's some other kind of traffic. I am no good at morse either, but you could write it down as dots and dashes and try to decode it later. Is it repetetive? Maybe it's just a radio beacon identifying itself.

Well thats my problem, I can't hear the difference between a dot and dash. It just sounds like beep beep beep beep. I can read code if you write it out as _._. _ _._

If you hear it again, try to get a fix on frequency, exact time, etc.
Shortwave reception here is terrible with all those computer buzzes,
but someone is bound to find out. Bye for now.

Often heard by me in New Zealand at about 0800UTC on 5898kHz USB is a woman's voice reading out five-number groups in Spanish. I believe she is one of the transmitters of "Atencion" as apparantly this is what she starts her transmission with. Do thay speak Spanish in the Philipines, or is it coming from Cuba, given that at the same time I can hear NY aeradio, Shannon and West Drayton, all on low frequencies?

It's funny that you say that, I was looking for Arnie Corro's Show on Radio Havana, and thought this was it. He has some interesting tech tips on Ham radio. He starts his show with a few seconds of Morse code.

Your comment about morse just sounding like 'beep beep' reminded me of when back in 62/63 when our class of 17 and 18year olds were learning morse for the UK Marine Radio Exams. We had learnt the basics, but were told that to really drum it into our subconscious we should practice all the time by sounding off everything we saw written on anything. Also we had to use 'dah' and 'dit' instead of dash and dot as the sound length was right. So there we stood at the bus stop after college going "ditdahditdit dahdahdah dahdit etc" when a London Transport bus went passed. The non-students seemed to move away a couple of paces - I wonder why?

As a Communication Engineer for past 23 years, I shall say the Morse is still considered the most effective and simple way of communication. One can transmit code with few parts, including a power source, like you car battery (All hand held HAM equipments use 12-Volt). I have passed the code and have General-Class FCC License. If I recall correctly, the ARRL transmits code on certain days and on certain frequency for educational purpose and to assist start learning the topic. If you ever got lost, just remove the spark-plug wire from one of the cylinder of you car and start your car. Due to jamming effect, you can be located in short time. This is similar to code, but much broader frequency.

I hope I have been helpful.

More topics are available at arrl.org website
Vahid