SG-2000 MANUAL
62
The SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
©1995, SGC, Inc.
TEL: (206) 746-6310 FAX: (206) 746-6384
VOC - TLX
The standard SG-2000 has two selectable audio filters which
allow the user to optimize the reception of incoming voice or
data signals. The Voice filter, (VOC) allows a wide band
width of 400 Hz to 2400 Hz. The second, the Telex (TLX)
filter, is a tight filter centered at 1700 Hz. This filter increases
the "signal to noise ratio" of the frequencies used in SITOR,
RTTY, and FEC communications by removing unwanted
noise.
Technical note for advanced users:
SG-2000's which have been ordered for
ALE (Automatic Link Establishment), or adaptive HF controller service
employing Digital Signal Processing (DSP) systems are specially modified
to use the VOC-TLX switch to turn the automatic (receiver) gain circuits
(AGC) on and off. This configuration is selected by moving a jumper on
the exciter board of the radio. ALE and other advanced government
protocols require that automatic gain control circuits be defeated. This
modification allows the AGC speed switch to be called via the serial port.
The modification removes the TLX filter function which is not used under
wide spectrum digital protocols. The PRC-2250 MIL is supplied standard
with the ALE modification selected by the internal jumper.
SQL
The squelch is used to block non-voice reception (e.g.
atmospheric background noise) and is incorporated in most
SSB transceivers. The SG-2000 converts the signal to a digital
form. The signal is then analyzed by the micro-processor to
determine if it is a voice signal. If the signal is determined to
be voice, it is allowed to pass. If not, the radio remains silent.
This feature provides a faster response time to the incoming
signal so that no data is lost.
SPK
This button will engage the front panel speaker on or off. This
feature is utilized when the privacy of using a telephone style
handset is desired. The SG-2000 back panel speaker jack (J-505)
is also controlled by this switch. Please note that when the SG-
2000 is first turned on, all control heads are nor-malized at one
half volume, regardless of the last setting of the SPK switch.
Note: External Speaker jack J-505 is only usable when the SG-
2000 is used in the control head attached to the radio
configuration.
20 DB ATTN
This control inserts or removes a special -20 dB receiver gain
reduction pad in the front end receiver of the SG-2000. When
this pad is in the ON position, the SG-2000 reduces it's sen-
sitivity to overcome unwanted RF noise, interference signals