Applied Systems Engineering BCOM-USB User Manual

ASE2000 V2 Communication Test Set User Manual 94
16. ASE BELL-202 Dual-Channel Modem Adjustment
This section illustrates and explains the gain and sensitivity adjustments on the ASE Bell-202
Dual-Channel Modem.
T
X
L
R
X
L
C
D
L
T
X
L
R
X
L
C
D
L
Off
On
Monitor
Mode
Dual Channel ModemMODEM B MODEM A
Modem Adjustments
The modem contains six potentiometers as shown in the diagram above, three for Channel A
and 3 for Channel B. The adjustments control transmitter gain, receiver gain, and carrier detect
sensitivity levels.
Note: There are two types of potentiometers that are assembled in the modems.
Most of the modems are supplied with white potentiometers but some modems
manufactured after 1998 have yellow or orange colored potentiometers. The
adjustment direction for these potentiometers is reversed from the white
potentiometers. Consequently, the meanings of cw and ccw are interchanged.
Make sure you identify the type of potentiometer before attempting adjustments.
The type of potentiometer can be determined by looking through the adjustment hole to determine
the color.
16.1. Adjusting Modems with White Colored Potentiometers
TXL Transmitter Gain - Factory setting is 1/8 of a turn from the counter-clockwise (ccw) end.
Transmit levels range from –50 dBm in the ccw direction to –6 dBm in the clockwise (cw) direction.
RXLReceiver Gain - Factory setting is ¼ of a turn from the counter-clockwise end. Receive
sensitivity levels range from –6 dBm in the ccw direction to –54 dBm in the cw direction.
CDL Carrier Detect Sensitivity - Factory setting is completely counter-clockwise. Sensitivity is
–30 dBm in the ccw direction to –48 in the cw direction.
TXL Transmitter Gain - Factory setting is 1/8 of a turn from the counter-clockwise
(ccw) end. Transmit levels range from –50 dBm in the ccw direction to –6 dBm
in the clockwise (cw) direction.
RXL Receiver Gain - Factory setting is ¼ of a turn from the clockwise end. Receive
sensitivity levels range from –6 dBm in the cw direction to –54 dBm in the ccw
direction.
16

Applied Systems Engineering BCOM-USB Specifications

General

Brand	Applied Systems Engineering
Model	BCOM-USB
Category	Measuring Instruments
Language	English