What is a Shortwave Radio and How Does it Work?

A shortwave radio receives transmissions on the shortwave radio frequencies. Shortwave radio frequencies include all high frequency bands (HF bands) and extends beyond the medium frequency bands.

These radio frequencies are broadcast at an angle going above the ground level. They are reflected back from the atmosphere allowing them to travel long distances across the earth. This angle broadcast is called skywave or skip propagation.

Shortwave radio signals have been used for decades to allow for the transmission of signals from continent to continent and beyond the horizon with good reception.

Shortwave has been used for everything from music and news broadcasts, to military and diplomatic communication that requires beyond horizon reach.

Today shortwave radio is also used by amateur radio enthusiasts, marine, aviation and even educational broadcasts.

Shortwave Radio Audio Modes

AM: AM, Amplitude modulation, is commonly utilized for shortwave signal broadcasting.

Single sideband (SSB): Another form of AM that adds filters of the modulation. This is utilized to reduce the transmission power and to reduce the bandwidth. Single sideband receivers are more complicated than standard AM receivers. Sing sideband is generally used for marine VHF radio and aviation communication and amateur radio operators.

Vestigial sideband (VS): VS filters out most of the other sideband and is considered a good compromise between AM and SSB. It utilizes simpler reveivers than SSB while using similar amounts transmitting power as AM. It also utilizes about half as much bandwidth as AM. Vestigial sideband is used for television, both analog and digital.

Narrow band frequency modulation (NBFM and NFM): This band has a larger bandwidth and is utilized for VHF communication. It is best used with FM signal as it is used for short range transmissions.

Digital Radio Mondiale (DRM): This is a digital modulation for bands below 30MHz. It is utilized for broadcasting audio signals.

Data Modes

Continuous Wave (CW): CW is utilized for Morse code and teleprinter transmissions.

Radioteletype: Utilizes frequency shift keying and audio subcarriers used for fax, digital, and slow scan television. These signals require decoding from sound card equipped computers.

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