SG-2000 MANUAL
115
The SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
©1995, SGC, Inc.
TEL: (206) 746-6310 FAX: (206) 746-6384
The data stream which is first established between ALE stations is called the ALE
orderwire. It is designed to pass network traffic and to introduce standards
beyond FS-1045 for network administration including text store, forward, and
other enhanced data operations.
18.1
SG-2000 Serial Port Operation
The SG-2000 can operate under the new U.S. Government Automatic Link
Establishment protocol defined under standard FED-STD-1045 and under the
military standards MIL-STD-188-141A. The SG-2000 will operate at both the 2
channels per second scan rate and the 5 channels per second scan rates defined
by the standard.
An ALE station comprises an ALE controller unit, a high performance HF SSB
radio, and support peripherals. These peripherals may include a dumb
ASCII/ANSI terminal or an IBM PC or AT capable of emulating a dumb ASCII
terminal.
The ALE unit, used in conjunction with an SG-2000, performs link quality
analysis (LQA) on the ALE signals between stations. LQA information is used in
selection of the best channel for calling and communicating. The ALE controller
automatically identifies the best channel to speed connections and to provide
optimum performance. Quality information on other channels is logged for
future reference.
In addition, when under ALE control, the SG-2000 will not interfere with active
ALE traffic channels and will exchange LQA information only with other stations
when requested.
The significant advantages of ALE are obtained through the use of forward error
correction, (Golay) data interleaving, and redundancy to enhance performance
and to provide for error free message traffic. The ALE controller utilizes a digital
signal processing unit to perform various linking, analysis, and signal processing
functions.
The controller can retrieve and operate on up to 100 channels. These may be
selected from any of the preprogrammed memories within the SG-2000 or may
use the user defined channels or any combination of preprogrammed and user
defined channels.
When not linked, the ALE configured SG-2000 will continuously scan a
preselected series of channels, listening for ALE calls, and will be ready to
respond. The scanned channels are selectable in groups or individually within a
group to provide total flexibility in channel and network management. The scan
rate of the ALE controlled SG-2000 is either 2 channels per second or 5 channels
per second.