Walter Drake SW8 - Manual (Page 31)

Glossary of Terms 25
1) AC Input - Alternating Current power source
available at wall outlet sockets.
2) AM - Signals in which the information is conveyed
by amplitude changes of the signal. Amplitude Modula-
tion is used for the AM broadcast bands.
3) AGC - Automatic Gain Control which is employed in
receivers to adjust the amount of gain in the receiver's
circuitry to prevent distortion and maintain a nearly
constant audio volume level over wide variations in
received signal strength.
4) Attenuation - Loss, as applied in the text of this
manual, added prior to the input stages of the receiver
to reduce the level of very strong signals that may
occur on certain bands, in certain locations, at certain
times or a combination of all three factors. Each 10 dB
(decibel) step reduces the power of the received signal
by a factor of ten.
5) CW - Continuous Wave transmission signals.
Actually, the signal is keyed on and off at precise
intervals to convey information. Morse code is the
most common CW signal.
6) DC Input - Direct Current power source such as is
available from batteries or regulated power supplies.
7) Dynamic Range - Ability of the receiver to faithfully
reproduce high quality audio over a wide range of
signal strength conditions - from very weak signals to
very strong signals.
8) Frequency - Rate of reoccurrence in hertz or
cycles/second of electromagnetic wave or carrier.
9) FM - Signals in which the information is conveyed
by frequency changes of the signal. Frequency Modula-
tion is used for the FM broadcast bands.
10) Electronically Switched Filter - A multi bandwidth
filter with high adjacent channel attenuation switched
electronically.
11) GMT - Greenwich Mean Time.
12) HF - High Frequency band extends from approxi-
mately 1.5 MHz to 30 MHz.
13) LCD - Liquid-Crystal Display - Low power
consumption displays used for wristwatches and
information displays on many types of electronic
equipment.
14) LSB - Lower Side Band - The lower frequency
portion, excluding the carrier, of an AM signal. A
single-sideband signal, in this case the lower sideband,
contains all of the modulation information of amplitude
modulation in one half the bandwidth.
15) RF - Radio frequency
16) RTTY - Radio Teletype communications.
17) Squelch - A user controlled adjustment which
mutes the audio output below a certain signal strength.
18) Synchronous Detector - An amplitude modulation
detector which utilizes a replica of the original trans-
mitted carrier signal to improve the reception of weak
signals.
19) Synthesized - Capable of generating a large
number of different output frequencies, all related to a
single, highly stable reference source.
20) Up Conversion - A frequency conversion tech-
nique that translates an incoming RF signal to a higher
frequency.
21) USB - Upper Side Band - The higher frequency
portion, excluding the carrier of an AM signal. A single-
sideband signal, in this case the upper sideband,
contains all of the modulation information of amplitude
modulation in one half the bandwidth. .
22) UTC - Universal Time Coordinated.
23) VFO - Variable Frequency Oscillator
24) VHF - Very High Frequency band extends from
approximately 30MHz to 300 MHz.