Numbers Stations

Oh yes, a band I know here in Toronto changed their name to Vivaldi's Amp after the guit amp wouldn't stop bringing in Vivaldi between songs.
My base station is a CB... Realistic Navaho TRC-432 I thimk... the antenna is missing.
I want to play a couple Tap songs, like Majesty of Rock, but no-one is up for it.

J Riff said:

My base station is a CB... Realistic Navaho TRC-432

Click to expand...

So no Shortwave, no VHF, just CB band (26.5MHz to 27.9MHz depending on country). I suspected that.
Realistic is Tandy / Radio Shack badge, probably same model as some other make. Radio Shack are recently gone.

I love these things, too. I've written a shortish story 3/4ths the way through inspired by Numbers Stations. They're used quite interestingly in Fringe and in the superb movie The Banshee Chapter.


pH

Has any one heard of the Russian Woodpecker, my brother used to regularly pick it up on his short-wave set.
It was a continual repetitive tapping tone a bit like a manic woodpecker.
I later found out the it was an attempt by the Russians to develop over-the-horizon radar.
You can read about it on Wikipedia under "Duga-3".

It was over the horizon radar. It's gone.

Strictly speaking WWII UK Radar was far over the the optical horizon.

Stealth aircraft invisible on modern radar show up on lower frequency obsolete radar systems.

REF: Ray McCarthy
Come back Chain Home, all is forgiven!!!

P.S.
Talking about early radar, whenever I see a documentary about the Battle Of Britain they always obviously go on about it's importance.
It was very important, however this was only one part of the tracking system.
The radars were great for looking outwards to France and Holland, giving a good early warning of a raid building.
But once the planes were past the coast and inland they could no longer be seen by radar.
The rest of the job of tracking them fell to the Observer Corps.
Armed with binoculars, sighting gear and a telephone they did an outstanding job of keeping track of the raiders inland.
Mainly made up of civilian volunteers I don't think they have received the recognition they deserve.

BigBadBob141 said:

But once the planes were past the coast and inland they could no longer be seen by radar.
The rest of the job of tracking them fell to the Observer Corps.

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They did add other Radar systems at other locations, airbases and on planes as the war progressed.

One of the worst losses, testing the airborne systems
https://en.wikipedia.org/wiki/Alan_Blumlien

But in WWI and WWII sound and vision was used. The Observer Corp was obviously important initially,.

Although an SSB tuner makes listening to an SSB Shortwave broadcast easier, you can listen (sort of) on a standard AM tuner (that covers the shortwave bands). See http://www.hamuniverse.com/ssbinformation.html for info on amateur broadcast methods.
--Paul E Musselman

Esp. if you have a second shortwave radio to hetrodyne against it (tune the 2nd one 455kHz higher or lower). Adjust spacing for best effect. The local oscillator of the second set adds the missing carrier so that the AM detector works.

However image rejection, intermodulation is poor and bandwidth too high. A second hand Sony ICF2001D is a bit cheaper than an AM /FM LW/MW/VHF "Roberts revival" which is x10 more price than same quality Tesco World band set, which has LW/MW/VHF and NINE AM shortwave bands too, for €10 (no SSB though). It's about the only radio Tesco sells that's any good. The speaker is tiny & tinny but it's fine on headphones or a decent 4" external speaker.
http://www.tesco.com/direct/tesco-rad-108-world-band-radio/498-0233.prd
There are lots of similar style Chinese ones (and even a Roberts at silly expensive price). But all the other ones I tested didn't have LW and were rubbish on MW as they had only a ferrite slug instead of a proper MW ferrite rod aerial. I buy radios, test them and take them apart!


The Sony ICF2001D has AM, narrow AM, Synchronous AM (upper or lower side band to avoid co-channel whistles), SSB (LSB-CW and USB) 150KHz to 30MHz, VHF-AM Air band and VHF-FM (covering Japan, USA and Western Europe VHF-FM bands, but not the nearly gone East European OIRT VHF band). It's dual conversion, so decent image rejection and bandwidth. I don't think any of the domestic consumer radios sold today are as good, you need specialist Amateur or Professional sets now. There is a slightly different US version (ICF2010D possibly) and Middle East Version.
http://www.radiomuseum.org/r/sony_icf_2001d.html
Only really available on eBay as they are about 30 years old!

The common PLL digital display clock radios are useless as it's up/down buttons and most are poor single chip implementations. Only any good as a local FM Radio alarm clock. Unusable LW (if even fitted) poor MW and worse SW.

BigBadBob141 said:

Has any one heard of the Russian Woodpecker, my brother used to regularly pick it up on his short-wave set.
It was a continual repetitive tapping tone a bit like a manic woodpecker.
I later found out the it was an attempt by the Russians to develop over-the-horizon radar.
You can read about it on Wikipedia under "Duga-3".

Click to expand...

Spoiler Alert... It sounds like the Venetian Blind blowing in the wind, while tied to the Morse Code straight key in the film On The Beach. I wonder if it was an inspiration for that scene?

I've only read the book

I haven't read the book but it is a major letdown in the film when the travel all that way thinking it is a human being. It's near the end, so I've completely spoiled that film for anyone who hasn't seen it.

Morse (CW) is just a carrier on/off, so is a pure tone, the exact pitch depending on the receiver's tuning.
The woodpecker didn't sound like cw at all. Quite harsh, though I've not heard it for many years.

A blind blowing in the wind hitting a key wouldn't sound like Morse as it has a distinctive rhythm no matter what speed it is.

-- --- .-. ... . / -.--.- -.-. .-- -.--.- / .. ... / .--- ..- ... - / .- / -.-. .- .-. .-. .. . .-. / --- -. -..-. --- ..-. ..-. --..-- / ... --- / .. ... / .- / .--. ..- .-. . / - --- -. . --..-- / - .... . / . -..- .- -.-. - / .--. .. - -.-. .... / -.. . .--. . -. -.. .. -. --. / --- -. / - .... . / .-. . -.-. . .. ...- . .-. .----. ... / - ..- -. .. -. --. .-.-.- / - .... . / .-- --- --- -.. .--. . -.-. -.- . .-. / -.. .. -.. -. .----. - / ... --- ..- -. -.. / .-.. .. -.- . / -.-. .-- / .- - / .- .-.. .-.. .-.-.- / --.- ..- .. - . / .... .- .-. ... .... --..-- / - .... --- ..- --. .... / .. .----. ...- . / -. --- - / .... . .- .-. -.. / .. - / ..-. --- .-. / -- .- -. -.-- / -.-- . .- .-. ... .-.-.- / .- / -... .-.. .. -. -.. / -... .-.. --- .-- .. -. --. / .. -. / - .... . / .-- .. -. -.. / .... .. - - .. -. --. / .- / -.- . -.-- / .-- --- ..- .-.. -.. -. .----. - / ... --- ..- -. -.. / .-.. .. -.- . / -- --- .-. ... . / .- ... / .. - / .... .- ... / .- / -.. .. ... - .. -. -.-. - .. ...- . / .-. .... -.-- - .... -- / -. --- / -- .- - - . .-. / .-- .... .- - / ... .--. . . -.. / .. - / .. ... .-.-.-

See
http://morsecode.scphillips.com/translator.html
note the default there is 30wpm, which is rather fast. Re-try at about 22
Minimum to pass an exam might be 12. Best to learn at about 15, too slow and you don't catch the rhythm and can't get faster.

Writing a program to generate morse is trivial (I've done it in several programming languages). Even in 1930s there was ability to generate paper tape from QWERTY teletype keyboard. The tape could be fed at any speed on the transmitter.

Decoding received morse by computer is very much harder and can have these stages:

1. Decoding the tone to on/off
2. deciding if on is a dot or dash
3. deciding if off is an inter symbol pause, inter letter or inter word pause.
4. Adaptive loop to re-determine timings
   
5. dictionary look up of morse strings to text.

I did a program in VB6 with the first stage using off the shelf tone decoder DSP. It only worked with very good Morse. The morse decoder in some commercial programs was far better (MiixW). A retired Marine Radio operator I know has good enough morse for the MixW software. People in contests use all pre-prepared computer generated replies.