CW

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mainetrunk

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Hi guy's, while slowly working on my hf knowledge, I now ask--- What is CW used for? I know it is CONTINUOUS WAVE, but what's the deal, digital, ,,,,,? Thx
 

KC8ESL

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In the words of the movie "Independence Day" -

**In a proper British accent** "its old morse code."

CW is continuous wave, A1A modulation. Typically 800hz in tone if you're trying to zero the signal.

Tune between 7.000 - 7.150 MHz or 14.000 - 14.150 MHz just about anytime of the day on any shortwave radio and you'll hear the distinct dots and dashes.
 

KC8ESL

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I'd imagine there will always be some diehard out there in the future banging away at a code key. Right now there are still tons of signals originating from ham radio operators. It's all but dead anywhere else outside the ham bands and CWID's of commercial/public service repeaters.
 

k9rzz

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For us old codgers ... CW is LIFE.
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Just give me a set of cw paddles and you can throw that computer away.

Truth be known, the morning alarm on my phone is some W1AW morse code. Seriously!
icon10.gif
 

Token

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As said before, CW is a generally accepted (in the Communications and Ham world) way of saying Morse Code. You can stop reading right here if that is all you wanted to know.

It would be more correct to say when discussing the transmitted signal that it is likely "ICW", or Interrupted Continuous Wave (the interruptions are used to form the dots and dashes of the Morse code), and the receiver is commonly used in the "CW" mode (if so equipped) to receive these signals. If the receiver does not have a "CW" mode you can use one of the sideband modes instead, either USB or LSB, to hear the Morse code. Even if you use sideband to hear the Morse it is still commonly called CW.

OK, so why do I bother to confuse the issue by bringing this minutia up, when "CW" is an almost universal way (in the communications and ham worlds) of saying "Morse Code"? Because there are other methods of sending Morse Code besides the ICW I mention above, and they may, or may not, involve an interrupted continuous wave. An example would be FSK-CW (Frequency Shift Keying CW), were the Morse is made by shifting the transmitted frequency to form the audio dots and dashes. In such a case the "CW" position might, or might not, depending on FSK shift and receiver CW filter width, be usable to receive the transmission. Another example would be MCW (Modulated CW), were the Morse is modulated as an audio tone on a carrier, this is commonly done with AM (Amplitude Modulation) or FM (Frequency Modualtion). Typically the CW receiver mode is useful to hear the Morse when the transmissions are in AM, but sometimes less so when the transmissions are in FM. In both of those cases the preferred demodulation method is the correct mode, AM or FM. Note that all of these modes still use the term CW in their names to designate that there is Morse code involved.

But outside the Communications or Ham world the term "CW" takes on a completely different meaning, it means an unmodulated carrier with NO data at all (Morse code is data, after all).

Why does this particular use of the term CW matter on an HF or short wave oriented forum like this? Because many of the HF radars a person sees on the bands use a transmission technique called "FMCW" (there can be various types, IFMCW, LFMCW, SFMCW, etc). And these transmissions typically do not involve Morse Code at all.

The take away here is that when, in the radio world, you see or hear the term "CW" it probably, almost certainly, means Morse Code transmitted over a radio. However there is a chance it does not, so pay attention to the context.

T!
 

mainetrunk

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Thanks T, I have heard it in USB and LSB. I just thought it was like wx buoys transmitting current stats or mil... I'm just trying to weave thru 1,000,000 sounds out there. Thanks again guys
 

KG4NEL

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This weekend is the ARRL November CW Sweepstakes. If you want to hear lots of CW signals, no better time for it, except maybe during CQWW CW or CW WPX :)
 

Boombox

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CW can be fun to learn, but can be a bear to learn well if you don't really concentrate on it.

I know just enough CW to copy 5-7 wpm, or read ham stations' call signs in the CW portions of the ham bands. Sometimes the CW portion of the ham band is more interesting than the SSB part of the band.

Most CW QSO's (contacts / exchanges) are callsign and a couple other things, just quick contacts. Fairly standardized.

Callsign, location (sometimes), "5NN" (signal report of 5-9-9 in code shorthand) -- it's fairly easy to pick up on it once you learn all the letters and numbers in CW. I first started listening to the CW band by listening for guys calling CQ, as those are fairly simple to read: CQ CQ DE (fill in call sign here) K. Sometimes you hear DX from Europe and Asia that way, just by hearing them call CQ.

If you want to learn it and then find something to listen to, aside from W1AW's code practice transmissions, in the CW part of the 40 meter band you will generally find a lot of slow CW contacts.
 

AA6IO

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For us old codgers ... CW is LIFE.
icon10.gif


Just give me a set of cw paddles and you can throw that computer away.

Truth be known, the morning alarm on my phone is some W1AW morse code. Seriously!
icon10.gif

CW is a big part of my life too. Been a ham for 52 years. However, I will keep my 6 computers. SDR is the wave of the future, and in fact, has been for some time.

Steve AA6IO
 

mainetrunk

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cw--life.... fun

Great, thanks guy's.. But, you say it can be fun to learn? Let me ask you guy's a fun question.( offbeat here ) In this HF radio world, we got CW,USB,LSB,,,,,,, what is the funnest?
A--just getting the receiver--$$
B--getting the right antenna
C--making your own antenna
D--turning the knob, aka--tuning
E--learning the way airwaves work
F--all of the above
I go with F...
I just got done moving my balun wires into place, time to ---turn the knob----, look forward to many hit's, and start learning the "" beep beeps"" hahaha
 
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lep

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During my active working career I often went to Geneve Switzerland which of course is in the French speaking part of the country, although years ago in College I had a couple of courses I was never really comfortable with it. A friend, a retired language teacher explained the first time she was on a bus in Paris and realized she was understanding a conversation without translating it, it was like a light bulb turned on.
It is the same way with CW, if you are really good it is just another language so you hear the Words and Sentences, not the characters to be translated.
BTW, only in contests or dxpeditions does CW consist only of names/signal reports
 

KG4NEL

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majoco

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More misinformation...

CW is continuous wave, A1A modulation. Typically 800hz in tone if you're trying to zero the signal.
CW = carrier wave
A1A = no modulation, telegraphy by on-off keying of the carrier wave.
A2A = modulated carrier wave telegraphy, usually by keying the carrier wave and the modulating tone together.
(source...http://www.ac6v.com/modcodes.htm)

The beauty of CW A1A is that it gets through noise and interference much better than voice (AM or SSB) because on a good receiver you can reduce the bandwidth right down to very narrow to get rid of all the extraneous stuff. You are only receiving the carrier - no modulation sidebands - hence sometimes called "Single signal" reception. Some (trans)receivers (like my old Yaesu FT-901D) had a tunable audio filter that would really peak up the signal too.
 
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KC8ESL

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97.3 leaves it open for debate as it only gets described as "cw".

(1)*CW.*International Morse code telegraphy emissions having designators with A, C, H, J or R as the first symbol; 1 as the second symbol; A or B as the third symbol; and emissions J2A and J2B.


It also goes on to state:

(4)*MCW.*Tone-modulated international Morse code telegraphy emissions having designators with A, C, D, F, G, H or R as the first symbol; 2 as the second symbol; A or B as the third symbol.

I fail to see how my info was wrong.
 

Token

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97.3 leaves it open for debate as it only gets described as "cw".

(1)*CW.*International Morse code telegraphy emissions having designators with A, C, H, J or R as the first symbol; 1 as the second symbol; A or B as the third symbol; and emissions J2A and J2B.


It also goes on to state:

(4)*MCW.*Tone-modulated international Morse code telegraphy emissions having designators with A, C, D, F, G, H or R as the first symbol; 2 as the second symbol; A or B as the third symbol.

I fail to see how my info was wrong.

I did not see anything you said as wrong. OK, I would not have added the 800 Hz part, as that is totally dependant on how the receiver is set up. For example my radios are normally set to 600 or 700 Hz offset (works best for me), and I have seen a few that defaulted to 1 kHz.

However, keep in mind that ham radio is not the only RF service, and Part 97 does not set technical standards (such as the A1A etc designations), it only defines things for Ham applications. This is a ham forum, so here I can see the unanimous use of CW as Morse Code. As I said, outside the communications and ham world CW means truly Continuous Wave, it means unmodulated (keying the carrier on and off is modulating the carrier). In some of those circles what hams call CW would be called something like OOK (On-Off Keying) or ICW (Interrupted Carrier Wave).

Quoting Part 97 only addresses US hams. majoco is not located in the US and his governing body might not define it the same way (I don't know, I have not checked).

Yes, the classification of emissions (ex A1A, A2A) are international standards and should be consistent, but less official designations (like CW meaning Morse Code specifically) might be a little more ambiguous. A1A is without doubt telegraphy via on-off keying of the carrier, but International Morse code is not the only code that can be sent that way. American Morse, Continental Gerke, Russian Morse, Wabun Code, and Chinese Telegraph code could be (and in the case of Russian, Wabun, and Chinese, still are) sent using A1A. I think in all of these cases we as a community would still call it CW, despite them not being Morse Code.

T!
 
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