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NFM is the most common mode used above 30 MHz with the exception of the airbands. NFM is
widely used on the VHF bands: VHF marine band, 2m amateur band, 70 cm amateur band, PMR
(Private Mobile Radio) and utilities.
In the absence of a signal, the background white noise may appear quite loud. For easier listening,
the squelch control should be rotated c lockwise until the background noise disappears this should
be carried out while no signal is present. The point at which the background noise is cancelled is
known as the threshold point. Do not advance the squelch control more than necessary or the
receiver will appear to be desensitized and weaker signals will be missed.
WFM – Wide Band Frequency Modulation
Used by VHF and UHF broadcast stations as excellent audio quality.
This is available due to the relatively wide frequency bandwidth employed.
Used only for local services such as VHF band stereo channels.
LSB – Lower Side Band / A form of SSB (Single Side Band).
Not intended for commercial use but is extensively used by Radio Amateurs on frequencies below 10
MHz. This assists in the separation of Commercial and Amateur users on traditionally shared bands and
prevents them from speaking to each other.
SSB is a very efficient method of transmission as the unwanted second sideband and carrier have
been removed. This allows the full transmitter power to be employed in carrying use ful information
within the wanted sideband. As a result, greater distances are possible on SSB and a smaller
frequency bandwidth is required than with most other modes.
USB – Upper Side Band
The same comments apply as for LSB. By conventio n, Radio amateurs also use USB above 10 MHz.
ISB – Independent Side Band
Similar to SSB, however, 2 independent SSB signals are transmitted on the same frequency.
Decoded signals can be heard separately from the headphone jack on the front panel.
CW - Continuo us Wave
Also referred as Carrier Wave or Morse Code.
Commonly used on the s hort wave bands by ra dio amateurs toward the lower end of each band
allocation. Some commercial use is still made by shipping etc although its use is being phased out due to
the introduction of a utomated stations.
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