User's Manual

GLOSSARY
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© RF Innovations Pty Ltd, 1998 Page: 102
234839, Revision 2.2
Serial Port
Port that receives/transmits serial data. The RFI-9256 has two serial ports, the Main and Auxiliary (Aux) ports.
Simplex
Data communications in one direction only.
Slave
Passive modem. Requires a Master to synchronise timing to enable successful transmission. May initiate communication, but
can only communicate with the Master.
Software
Computer program or set of computer programs held in storage, and loaded into RAM for execution.
Software Handshaking
A method of controlling the flow of data between two computers or terminals. Special control characters are sent from one
terminal to the other in order to halt or recommence the flow of data. See also Hardware Handshaking.
Spread Spectrum Modem
Modem that operates within a frequency band (as opposed to operating at a single, fixed frequency), jumping through the
frequencies according to the Hopping Pattern.
Spread Spectrum Standard
Standard that specifies the way in which the frequencies of the spread spectrum are to be utilised.
S Registers
Registers, inside the modem, which contains whole number values. These can be read and obtained from remote modems by
using a communications link. Examples include Escape Sequence Guard Time, Number of Retries for ARQ.
Start Bit
When a character is transmitted asynchronously to another computer, a start bit always precedes the actual data. Seven or
eight data bits, an optional parity bit and a stop bit will follow.
Stop Bit
The last bit or element transmitted in asynchronous transmission of a character to return the circuit to an idle state. One or
two stop bits are sent at the end of each character of data.
Synchronous
A data transmission in which the time between characters is fixed by synchronising the transmitting and receiving
communications equipment. The clock signal is typically derived from the data stream in order to maintain synchronisation.
T
Telecommunications
The transmission of information across long distances, such as over telephone lines.
Terminal
An input/output device consisting of a typewriter-like keyboard and a display device, used for communicating with a large
computer. Any device capable of sending and/or receiving data over a communications channel.
Terminal Emulation
Refers to the type of ASCII terminal your software will imitate (the control characters used to perform certain screen and
cursor movement tasks vary from one terminal to another).
Terminal Program
Also called Terminal Software, terminal package, and emulator. Computer program that deciphers the information received
from the modem and send information to the modem as required.
Test Link Margin
Displays the average signal and noise the modem is measuring.
Text
The message portion of a data block in synchronous data transmissions.
Transmit Power
Power of signal emanating from the antenna. This should be the minimum required to maintain a solid data link.