Shopping on line can be easy, simple and save you lots of money. It can also take a lot of your time, frustrate you, and result in unwanted purchases. Now the same can be said for regular high street shopping, but with the vast opportunity presented by the Internet it will pay you to spend a few minutes reading this and understanding how to better optimize your Continuous Wave shopping experience:
1. Compare - without doubt the biggest advantage that the Continuous Wave offers shoppers today is the ability to compare thousands of Continuous Wave at a time. This is a great thing, but not necessarily all the time! Too much can be daunting at times so take advantage of the great comparison sites and where possible let them do the hard work for you.
2. Research - if it has been said it will be on the internet. Ignorance is no longer a justifiable reason for buying the wrong thing. Take the time to research in detail everything that you could possible want to know about
3. Testimonials - don't know anybody that has bought a Continuous Wave? Wrong! If the Continuous Wave is good the internet will let you know. Use the Internet as a friend and get testimonials before you buy.
4. Questions - Got a question about Continuous Wave then search the Forums, FAQ's, Blogs etc. Don't be afraid to ask .....
5. Reputation - Never heard of the company selling Continuous Wave? Don't worry, no reason why you should know every company in the world, but you know someone that does! Use the internet to find out what people are saying about Continuous Wave and build up a picture of their reputation for sales, returns, customer service, delivery etc.
6. Returns - still worried that even after all of the above your Continuous Wave wont be what you want? Check out the returns policy. There is so much competition now that someone, somewhere is bound to offer the terms that you are comfortable with.
7. Feedback - happy with your Continuous Wave then let people know, after all you are depending on others people input in your buying decision, so why not give a little back.
8. Security - check for the yellow padlock on the Continuous Wave site before you buy, and the s after http:/ /i.e. https:// = a secure site
9. Contact - got a question about Continuous Wave, or want to leave a comment then check out the sites contact page. Reputable companies have them and respond.
10. Payment - ready to pay for your Continuous Wave, then use your credit card or PayPal! Be aware of companies that don't accept them, there may be genuine reasons but given the huge amount of choice you have when buying online there is no reason at all not to buy via credit card or PayPal.
A
continuous wave or
continuous waveform (
CW) is an
electromagnetic wave of constant amplitude and
frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio
transmission (telecommunications), in which a carrier wave is switched on and off.
Information is carried in the varying duration of the
on-off keying of the signal. In radio transmission, CW waves are also known as "undamped waves", to distinguish this method from
damped wave transmission.
Radio
Very early radio transmitters used a spark gap to produce radio-frequency oscillations in the transmitting antenna; these signals had a characteristic rapidly damped amplitude during each pulse of radiated energy. When alternator#Radio alternatorss and later electronic
oscillators became available, the signal strength remained constant during each code element, leading to the description of this technique as "continuous" waves.
An unmodulated carrier has no bandwidth and conveys no information; the act of keying the carrier on and off produces a finite bandwidth relating to the transmission rate. Strictly speaking, a keyed carrier may be referred to as "ICW" for "Interrupted continuous wave" but the necessity of keying is usually understood.
Early radio transmitters were incapable of handling the complexity of actual audio and therefore CW was the only form of communication available. CW still remained a viable form of radio communication for many years after voice transmission was perfected, because simple transmitters could be used. The low bandwidth of the code signal, due in part to low information transmission rate, allowed very selective filters to be used in the receiver which blocked out much of the atmospheric noise that would otherwise reduce the intelligibility of the signal.
Continuous-wave radio was called
radiotelegraphy because like the telegraph, it worked by means of a simple switch to transmit
Morse code. However, instead of controlling the electricity in a cross-country wire, the switch controlled the power sent to a radio
transmitter. This mode is still in common use by
amateur radio operators.
A
continuous-wave radar system is one where a continuous wave is transmitted by one Antenna (radio) while a second aerial receives the reflected
radio energy.
In amateur radio, the terms "CW" and "Morse code" are often used interchangeably, despite the distinctions between the two. Morse code may be sent using
direct current in wires, sound, or light, for example.
Key clicks
In morse (on off carrier keying), if the carrier wave is turned on or off rapidly, the bandwidth will be large; if the carrier turns on and off more slowly the bandwidth will be smaller. The problem of excessive bandwidth used by a morse code transmitter which turns on/off too quickly is known as key clicks. Certain types of power amplifiers used in a transmitter may increase the problematic effects of key clicks.
Laser physics
In laser physics and engineering the term "continuous wave" or "CW" refers to a laser which produces a continuous output beam. This is as opposed to a
q-switched, gain-switching or
modelocking laser, which produces pulses of light.
See also
References
- Larry D. Wolfgang et. al, (ed), The ARRL Handbook for Radio Amateurs, Sixty-Eighth Edition , (1991), ARRL, Newington CT USA ISBN 0-87259-168-9
- CW Bandwidth Described
A
continuous wave or
continuous waveform (
CW) is an
electromagnetic wave of constant
amplitude and
frequency; and in mathematical analysis, of infinite duration. Continuous wave is also the name given to an early method of radio
transmission (telecommunications), in which a
carrier wave is switched on and off.
Information is carried in the varying duration of the
on-off keying of the signal. In radio transmission, CW waves are also known as "undamped waves", to distinguish this method from
damped wave transmission.
Radio
Very early radio transmitters used a
spark gap to produce radio-frequency oscillations in the transmitting antenna; these signals had a characteristic rapidly damped amplitude during each pulse of radiated energy. When
alternator#Radio alternatorss and later electronic
oscillators became available, the signal strength remained constant during each code element, leading to the description of this technique as "continuous" waves.
An unmodulated carrier has no bandwidth and conveys no information; the act of keying the carrier on and off produces a finite bandwidth relating to the transmission rate. Strictly speaking, a keyed carrier may be referred to as "ICW" for "Interrupted continuous wave" but the necessity of keying is usually understood.
Early radio transmitters were incapable of handling the complexity of actual audio and therefore CW was the only form of communication available. CW still remained a viable form of radio communication for many years after voice transmission was perfected, because simple transmitters could be used. The low bandwidth of the code signal, due in part to low information transmission rate, allowed very selective filters to be used in the receiver which blocked out much of the atmospheric noise that would otherwise reduce the intelligibility of the signal.
Continuous-wave radio was called radiotelegraphy because like the
telegraph, it worked by means of a simple switch to transmit Morse code. However, instead of controlling the electricity in a cross-country wire, the switch controlled the power sent to a radio
transmitter. This mode is still in common use by
amateur radio operators.
A
continuous-wave radar system is one where a continuous wave is transmitted by one
Antenna (radio) while a second aerial receives the reflected radio energy.
In
amateur radio, the terms "CW" and "Morse code" are often used interchangeably, despite the distinctions between the two. Morse code may be sent using
direct current in wires, sound, or light, for example.
Key clicks
In morse (on off carrier keying), if the carrier wave is turned on or off rapidly, the bandwidth will be large; if the carrier turns on and off more slowly the bandwidth will be smaller. The problem of excessive bandwidth used by a
morse code transmitter which turns on/off too quickly is known as key clicks. Certain types of power amplifiers used in a transmitter may increase the problematic effects of key clicks.
Laser physics
In laser physics and engineering the term "continuous wave" or "CW" refers to a laser which produces a continuous output beam. This is as opposed to a q-switched, gain-switching or
modelocking laser, which produces pulses of light.
See also
- Damped wave
- On-off keying
- Amplitude modulation
- Types of radio emissions
References
- Larry D. Wolfgang et. al, (ed), The ARRL Handbook for Radio Amateurs, Sixty-Eighth Edition , (1991), ARRL, Newington CT USA ISBN 0-87259-168-9
- CW Bandwidth Described
continuous wave from FOLDOC
continuous wave < communications > (CW) A term from early radio history, when the spark gap method of transmission was replaced by vacuum-tube oscillators.
Continuous wave - Wikipedia, the free encyclopedia
A continuous wave or continuous waveform (CW) is an electromagnetic wave of constant amplitude and frequency; and in mathematical analysis, of infinite duration.
Continuous-wave radar - Wikipedia, the free encyclopedia
Continuous-wave radar system is a radar system where a known stable frequency continuous wave radio energy is transmitted and then received from any reflecting objects.
Continuous Wave
Since 1994 the ContinuousWave website emphasizes high-quality content in the following subject areas: North Channel Lake Huron Cruising; Manitoulin Island; older Boston Whaler ...
continuous Wave: Whaler (Boston Whaler)
A website dedicated to boats made by the Boston Whaler company. Special emphasis is given to boats built from the original Boston Whaler hull designs. The website contains written ...
Continuous-Wave Magnetic Resonance Imaging of Solid Samples With Short ...
Principal Investigator: Professor DJ Lurie: Other Investigators: Dr J Hutchison: Researcher Co-investigators: Project Partner: Department: Biomedical Physics and Bioengineering
e-Prints Soton - Power scaling of continuous-wave adaptive gain ...
We demonstrate a power-scaling strategy in a continuous-wave adaptive phase-conjugate oscillator power amplifier (PCO-PA) system that actively corrects, via phase-conjugation, for ...
continuous wave definition of continuous wave in the Free Online ...
communications) continuous wave - (CW) A term from early radio history, when the spark gap method of transmission was replaced by vacuum-tube oscillators.
continuous-wave - definition of continuous-wave by the Free Online ...
adj. Abbr. CW. Emitting or capable of emitting continuously; not pulsed: a continuous wave laser; continuous wave radar.
Continuous Wave Intracavity Optical Parametric Oscillators
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