[9] Abbreviations and Terms

   Below is a short list of common terms and abbreviations relevant to
   shortwave radios. You can find more information on SW topics at:
     www.alphalink.com.au/~parkerp/shortwave.htm
   
Abbreviations
   
   AM  (Amplitude Modulation)
   BCD (Binary Coded Decimal)
   BFO (Beat Frequency Oscillator)
   C   (Ciudad; City)
   CB  (Citizens' Band [radio])
   cps (cycles per second)
   CW  (Continuous Wave; Morse code)
   DRM (Digital Radio Mondiale)
   DX  (old telegraphy code for Distant TRANSmitter)
   ECSS(Exalted Carrier Single Sideband)
   FM  (Frequency Modulation)
   FSK (Frequency Shift Keying) 
   GMT (Greenwich Mean Time)
   GPS (Global Positioning System)
   ham (amateur [radio])
   HF  (High Frequencies)
   kHz (kiloHertz)
   km/s(kilometres per second)
   LSB (Lower SideBand)
   LW  (LongWave)
   M   (Mega: 1,000,000)
   MW  (MediumWave)
   N   (North)
   No  (a contraction of Numero: 'number' in Latin languages)
   PLL (Phase Locked Loop)
   RTTY(Radio TeleTYpe)
   SSB (Single SideBand)
   SWL (ShortWave Listening)
   USB (Upper SideBand)
   UTC (Universal Time: by atomic clocks Coordinated to track GMT)
   VDC (Volts of Direct Current)
   W   (Watts)
      
Terms
   
   Amplitude Modulation: A technique that multiplexes audio frequencies
   onto the upper side of a carrier to produce the USB, and a mirror
   image of the audio frequencies beneath the carrier to produce the LSB.
   The resulting sideband pair is also known as Double Sideband (DSB).
   
   Beat Frequency Oscillator: A receiver circuit that generates a signal
   to emulate the carrier missing in CW, FSK, RTTY & SSB signals, and so 
   enable intelligible reception. 
   
   Carrier: A radio signal transmitted at constant strength & frequency
   - so providing a reference frequency for tuning in a transmission.

   Channel Separation: The frequency difference separating a channel from
   a neighboring one for a given band. 

   Channel Step: The frequency difference when moving to successive
   channels after having moved to a channel on a digitally-tuned radio.

   Continuous Wave: A radio signal transmitted at constant frequency &
   strength - except when interrupted to send messages by Morse code.
   
   DXing: listening to distant stations (D=distant, X=transmitter) 
   
   Exalted Carrier Single Sideband: A reception technique in which the
   BFO is used to insert a carrier over the received carrier of a signal.

   Frequency Step: An invariable frequency difference that ignores 
   channel allocations when quick-tuning a digitally-tuned radio.

   Hertz: cycles per second (= cps = c/s); metric unit of frequency.

   Ionosphere: A region in the upper atmosphere where free electrons &
   ions abound sufficiently to backscatter shortwave photons, so that
   some skip back to earth instead of just continuing out into space.

   Longwave: The range of frequencies from 30 to 300 kHz, although
   this term often is misused to mean any signal lower than 540 kHz,
   or limited to mean only its AM broadcast band (153 to 279 kHz).
   
   Lower Sideband: The sideband lower in frequency than the nominal or
   actual carrier of a transmission.

   Mediumwave: The range of frequencies from 300 to 3000 kHz (3 MHz),
   although this term is often limited to mean only its main AM broadcast
   band (at a minimum 540 to 1600 kHz).

   Shortwave: The range of frequencies from 3 to 30 MHz, although this
   term often is misused to include frequencies as low as 1610 kHz.

   Sideband: Those frequencies of a radio signal above or below the
   carrier, that either (as the USB) directly correspond to the original
   audio frequencies at the transmitter's input, or (as the LSB)
   inversely correspond in the form of a mirror image.

   Single Sideband: A modulation technique that suppresses one sideband
   entirely (and the carrier to varying degrees), leaving the remaining
   sideband essentially unchanged.
   
   Synchronous Detection: A demodulation technique found on many Sony
   shortwave portables and most advanced desktop receivers, that improves
   the reception of AM signals. Ironically, there is no 'AM radio' on the
   market that incorporates this feature. You will want it, if you spend
   much time listening to music. For listening to voice broadcasts when
   propagation is non-ideal, ECSS does as good a job, if not better.

   Tuning Step: The frequency difference when fine-tuning to move from
   one location to the next on a digitally-tuned radio.

   Upper Sideband: The sideband higher in frequency than the nominal or
   actual carrier of a transmission.
   
   Very High Frequencies: The frequency range from 30 to 300 MHz. The FM
   weather and broadcast bands are in the VHF band.
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