Glossary of Terms 43
1) AMSAT -
Amateur Satellite Corporation which designs,
builds and coordinates the launching of amateur
communication satellites.
2) AOS -
Acquisition of signal.
3) ack -
Acknowledge - Sending data to confirm the
receipt of other data that was initially sent.
4) AC Input -
Alternating current power source available
at wall outlet sockets.
5) 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.
6) Bird -
Satellite.
7) Call -
Call sign which identifies a particular amateur
radio operator.
8) Ctrl -
Control character sent from personal computer
or terminal keyboard.
9) DCD -
Data Carrier Detect
10) DC Input -
Direct Current power source such as is
available from batteries or regulated power supplies.
Lead acid storage batteries, such as employed in cars
and boats, have a 12-14 volt DC output which is the
proper operating voltage for the transceiver’s DC input.
Another requirement of the battery is its AMP-HR rating.
To determine the number of hours of operation before
battery recharging is required, divide the AMP-HR rating
of the battery by (2 AMPS) the current requirement of
the transceiver (assuming a duty cycle of 1 minute
transmit at 6 Amps and 4 minutes receive at 1 Amp).
11) Downlink -
The frequency from a satellite to a
ground station.
12) Esc -
Escape character sent from personal computer
or terminal keyboard.
13) Frequency -
Rate of reoccurrence in Hertz or cycles/
second of an electromagnetic wave or carrier.
14) FM -
Frequency Modulated signals, in which the
information or intelligence being transmitted, changes
the instantaneous frequency of the transmitter carrier.
Not to be confused with the FM Broadcast Band (FM
frequencies of 88 to 108 MHz).
15) FSK -
Frequency Shift Keying is a method of encod-
ing a signal by using constant-amplitude radio fre-
quency pulses having different frequencies, one fre-
quency for each of the possible message symbols.
16) LF -
Line feed control character sent to start a new
line of message or printing.
17) LCD -Liquid-Crystal Display -
composed of two
parallel glass plates with conductive coatings sandwich-
ing a liquid-crystal compound between them. The
compound becomes opaque and reflective when
subjected to an electric field. LCD displays are used as
information displays on many types of electronic equip-
ment.
18) LOS -
Loss of signal.
19) mS -
millisecond, 1/1000 of a second.
20) PACSAT -
Packet (data) satellite.
21) PC -
Personal computer.
22) PTT -
Push to talk, refers to the push operated switch
on a microphone attached to a transmitter.
23) RF -
Radio frequency.
24) RS-232C -
Electronics Industries Association standard
physical-level interface between DTE (terminal) and DCE
(modem).
25) RTTY -
Radio Teletype communications.
26) Squelch -
A user controlled adjustment which mutes
the audio output for received signals that are below a
certain strength.
27) Synthesized -
Capable of generating a large num-
ber of different output frequencies, all related to a
single, highly stable reference source.
28) TNC -
Terminal Node Controller, used for the trans-
mission and reception of packet data through a com-
munications link.
29) UHF -
Ultra High Frequency band extends from
approximately 300 MHz to 3000 MHz.
30) VFO -
Variable Frequency Oscillator.
31) VHF -
Very High Frequency band extends from
approximately 30 MHz to 300 MHz.