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I have been around Hams for twenty years and the tech has usually stayed interesting. During the late 80's packet radio was starting out. When most people were calling bbs's using modems, hams were sending wireless data. Check out Phil Karn's site. He has a lot of wireless experience as both ham and engineer responsible for much of the CDMA standard.

Want to start with some small radios and learn more about electronics at the same time? There are many interesting kits around if you look. You certainly don't have to spend huge amounts on radios to get started. I paid ~$120US for my VX-2R when they were first introduced. It makes a great general purpose scanner too.

Newer modes like PSK31 are incredibly efficient. A couple of watts of power and 31Hz of radio spectrum and you have error free world wide digital communication at 50wpm. It is difficult to audibly detect the signal while listening, even when you know it is there.

• CW = Continuous Wave, which is the method most often used to send Morse Code. Generally speaking, CW=Morse Code in this type of context.
• QSO = a conversation between two or more amateur radio operators. Note the QSO isn't an acronym, but rather a specialized code that's part of a larger set of Q Codes used to minimize sending common information during a CW conversation.
• HF = High Frequency, and in the above context I believe the author is referring to the bands between 3 mHz and 30 mHz (though CW is certainly used on all ham frequencies)
• QRP = As the author notes, the use of low power (as opposed to QRO, which is high power).

*grumble*

You would be correct.. I didn't read the history page that closely.

Therefore: "Here is a possible explanation as to how the USA got W and K, no documentation on this but sounds plausible. The USA had unofficially used N for North America (e.g., NBZ, Boston), also A for America. The letter "N" in morse is dah dit, adding a dah to N gives dah dit dah which is "K'. Letter "A" in morse is dit dah, adding a dah to A gives dit dah dah which is "W"."

source: http://www.ac6v.com/history.htm/

despite Devlin's 'liberal use of texting slang.

Some examples? `de' for `from', `cq' for `anybody out there?', `73' for `warm regards', etc. Here's some more examples for you.

Just thought I'd be fair ...

AD5RH (yes, I passed the morse code 5 wpm test. But only barely :)

Oh and I forgot, Morse code operators use many many abbreviations, as well as "Q codes", that put SMS-style shortcuts to shame. See at the bottom of this page for a fairly complete list.

It's not your house - it's all the stuff IN your house. Worst offenders are generic PCs; specifically their case design (RFI/EMI-wise) is absolutely clueless (e.g., see http://www.ac6v.com/comprfi.htm/ for theory and fixes). Second place is firmly held by very, very crappy power supplies that let all the noise OUT of the PC on the power buss (ie. into your wiring). Sam's very useful Notes on the Troubleshooting and Repair of Small Switchmode Power Supplies) will get you started with theory and what [often] goes wrong (disclosure: I'm his sidekick). But:

Pet Peeve: as soon as Name-Your-$14-PC-PS-Manufacturer gets their UL sticker (meaning they can start selling in the US!) the ENTIRE L-C filter from the input of the power supply PCB is shorted out with a series of jumpers. Right, the 120VAC wires go through the save-thy-ass fuse right into the rectifier! No caps, no chokes, nuthin'! (Ok, so what do you expect from a $15 460W PS?) This allows all the noise on the power lines to enter the PC (and fry it - use a surge protector!) *AND* it allows all the noise IN the PC to escape back out and corrupt others (ie. your receiver, TV, etc.) (See: http://cms-emc.web.cern.ch/cms-emc/pdffiles/PhDfil es/PS&filters.pdf section 3.2 Switching mode power supplies for a nice overview). Oh, yeah, and I'm *SURE* all of you have your grounded cable actually grounded, right?

I got a 250W ATX knock-off case for $29 that came with a PS included. Turned the PC on, *ALL* AM stations vanished! Right... I opened it up and shure enough, a jumper from fuse to rectifier. All caps to ground were missing as well (from various points in the circuit). A few moments with a soldering iron (jelly-bean components, salvaged from dead *quality* PSes) and you can't tell the PC is on by listening to AM dial. Day and night difference!

Don't feel bad if you never though of it, this guy obviously never did either... and he should have. http://techreport.com/reviews/2004q4/psus/index.x? pg=1

But, how do you later chop up the files? I'm glad you asked: I use a hacked version of text-only (yeah!) soundgrab. You can get my latest version from http://repairfaq.ece.drexel.edu/filipg/soundgrab/

My signal comes from a battery-powered (ie. avoids issues with 'corrupted power' ;) digital sony walkman, via a 20-odd foot coax cable to my PC. The further away your receiver is from the source of noice, the better off you are![*] Linux records it from a SoundBlaster Live! with rawrec to a wav file. I have a series of templates (.sg files) for different shows and just fudge them a bit then export to MP3. Piece of cake! I've done a bunch of Dave's shows that way (~700MB worth) for inclusion in a weakness of mine (don't worry, they get some equally-illegit music ;).

Cheers

[*] "The solution to pollution is dilution" - Evil chemistry maxim applied to the wonderul and friendly world of RFI ;-)

For actually encoding the data into an audio stream, I would suggest googling for Amateur radio data protocols using modulation schemes like MFSK, QAM, Raised Cosine, etc. Hams have been battling the narrow bandwidth problem for a long time, and have come up with many encoding schemes to protect the data against fading, multipath, etc (many of which are also present on cassette recordings). this site gives examples of digital modulation schemes, as well as a link to cool audio samples!

You might also google for "Phil Karn" or "KA9Q" - he's done a ton of work in this field. Also, the AMSAT or ARRL folk may have some info.

For actually encoding the data into an audio stream, I would suggest googling for Amateur radio data protocols using modulation schemes like MFSK, QAM, Raised Cosine, etc. Hams have been battling the narrow bandwidth problem for a long time, and have come up with many encoding schemes to protect the data against fading, multipath, etc (many of which are also present on cassette recordings). this site gives examples of digital modulation schemes, as well as a link to cool audio samples!

You might also google for "Phil Karn" or "KA9Q" - he's done a ton of work in this field. Also, the AMSAT or ARRL folk may have some info.

Alot of the shortened words used in netspeak, and the like have their origination in Radio. In morse code, words were shortened to increase the rate at which they could/can be sent. Rather then sending 4 characters for the word 'your' (-.-- --- ..- .-.) most operators simply sent 'ur' (..- .-.) - which on that particular phrase saves 50% of the amount needed to send the word. Another example being to send the character 'u' for the word 'you'. Other Abvr.s (Called prosigns) are also used to signify complete words and phrases like (.-.-.) for 'End of Message', (...-.-) for End of transmission, and many more (Morse Code Prosigns & Operating Aids.

Just a little bit more history on the subject - really makes one think where alot of the language
originated..

--Tucker Sizemore
W8EMX

There are two possibilities here.

Case A: Your receiver's front end is overloaded with the strong signal. Extremely strong transmitters will induce large voltages in receiver circuits that have automatic gain control circuits and 'fake them' into believing that the station they're listening to is extremely strong. That, or the front end amp simply can't handle the (relatively) large voltage coming in and it's just thrashing everything.

Case B: Skywave vs. ground-wave propagation. Radio signals from 1-50 MHz often bounce from earth to ionosphere and back, and often several times to get to your radio. That signal may be not propagating well via ground-wave to your current location, and the skywaves are effectively bouncing right over your head.

Here are a few links to get you started:

Realtime HF propagation news from qsl.net
Lots of info on propagation effects

Decibels are ratios between two levels, such as the amplitude of sound waves. Here are some relevant links and some excerpts I found using Google. The first explains the meaning in electronics, and the second is more about sound: The decibel, or dB, is a means of expressing the gain of an active device (such as an amplifier) or the loss in a passive device (such as an attenuator or length of cable). It is simply the ratio of output to input expressed in logarithmic form The decibel (abbreviated as dB, and also as db and DB) is a common unit of measurement for the relative loudness of a sound or, in electronics, for the relative difference between two power levels. A decibel is one-tenth of a "Bel", a seldom-used unit named for Alexander Graham Bell, inventor of the telephone. In sound, the difference between two sound levels is ten times the common logarithm of the ratio of their power levels. In sound, decibels measure a scale from the threshold of human hearing, 0 dB, upward towards the threshold of pain, about 120-140 dB. As examples: the sound level in the average residential home is about 40 dB, average conversation is about 60 dB, typical home music listening levels are about 85 dB, a loud rock band about 110 dB, and a jet engine close up is 150dB.