SG-2000 MANUAL
97
The SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
©1995, SGC, Inc.
TEL: (206) 746-6310 FAX: (206) 746-6384
16.0 Remote Control
There are three primary methods of controlling the SG-2000. One is by extension
of the control head wiring. Second is via short haul modems and auto-answer
telephone interface equipment. Third is via computer network and auto-answer
devices. The first method does not require any additional equipment. The
second two require the addition of the SG-2000 RS-232 option (SGC Part Number
52-34)
SGC does not warrant the remote installation of any unit in configurations which
exceed the 50 meter limit of the RS-422 standard used by the local area network
between control heads and the radio. This is not because extended operations do
not work, but rather because the distance between units blurs the responsibility
between the operator of the computer system and the provider of the
transmitter. As you can appreciate, the SG-2000 operates on a wide range of
platforms including networks which directly access the serial port.
If you are planning to operate the SG-2000 under control of the RS-232 software
supplied by SGC, please refer to the Accessories and Software portions of this
manual for additional information. ALE and serial control as applicable to
adaptive controllers is covered in its own section.
16.1
Extension of Control Head Wiring
The SG-2000 specifications call for remote control heads to be located within 50
meters (approximately 162 feet) of the radio's main unit which houses the
receiver, transmitter, and two of the three microprocessors plus the RS-232 and
RS-422 serial communication devices.
We have had reports that control heads have been operated at longer distances,
approaching in one case to more than one kilometer, but with slightly degraded
performance. The performance degradation which was noted included a slight
hum being added to the audio in both receive and transmit and, during severe
lightning storms in the immediate area, intermittent operation of the frequency
and mode controls.
The method used to extend the control head wiring, in this instance, was to find
a spare 25 pair shielded telephone line and then simply replace the 10 wire
control head wire with appropriate pairs. The most important portion of this
kind of installation is to provide a good DC loop for the Push-to-Talk (PTT)
circuitry.