SG-2000 MANUAL
99
The SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
©1995, SGC, Inc.
TEL: (206) 746-6310 FAX: (206) 746-6384
16.4
Auto-Answer Devices
Particularly when used by a network, the SG-2000 needs to get audio for transmit
and needs to send receiver audio somewhere. In order to accomplish this, the
radio is usually equipped with a telephone patch such as the SGC TEL-TWO
system. This unit incorporates a voice-operated-transmit (VOX) circuit which
provides automatic switching from transmit to receive when the telephone user
is listening and provides automatic activation of the transmitter when the
telephone user begins to speak.
The SGC TEL-TWO does not, however, provide a means of taking the telephone
drop equipment (called the "instrument" by consumers) to an off-hook condition.
This is because there are hundreds of telephone systems in the world today and
most of these are the new digital type. The particular signal level and signal
type which signals an "off-hook" condition to the digital switch is different from
the old fashion analog auto-answer scheme used in earlier telephone systems
such as the Western Electric 1A2 keyset variety.
For this reason, you will need to contact your telephone equipment provider to
insure that an auto-answering system is available for your telephone switch. If
you are using leased or dedicated pairs of phone lines for the circuit, such as at a
remote site, you may wish to construct a simple auto-answer circuit yourself, if
one cannot be provided by the local telephone company. Another option is to use
additional pairs and isolate functions to eliminate the need for the phone patch.
Circuit particulars will vary as widely as do telephone systems used throughout
the world.
16.5
Computer Networks - Serial Control
The SG-2000 may be controlled by a computer at the radio site by simply
connecting an appropriate serial line between the radio's rear panel "D"
connector, labelled RS-232, and the serial port of the IBM PC computer. We
prefer that the radio use COM-1, as COM-2 is generally used by telephone
modems.
If your plan includes access via modem, SGC supports the Norton
pcAnywhere™ remote computer software and the SG-2000. The process to begin
operation of the system is simple. pcAnywhere is started and the modem is
connected on COM-2. When pcAnywhere is running, the program SG2000.EXE
is started and will seek the first available serial port (generally COM-1) and will
initiate communication with the radio. This is covered in more detail in the RS-
232 documentation.
If you are operating a computer on a local area network, you may access the
serial port directly, if this is supported by your local or wide area network. If
this is the case, please refer to the section of the SG-2000 manual which covers