Section 365-336-202
3
pative mat, when handling modules outside of their protective packaging. A module intended for future use should
be tested as soon as possible and returned to its original protective packaging for storage.
This equipment contains staticsensitive electronic devices. To prevent electrostatic charges from
damaging staticsensitive units:
Use approved static preventive measures (such as a static-conductive wrist strap and a
static-dissipative mat) at all times whenever touching units outside of their original, shipped
static-protective packaging.
Do not ship or store units near strong electrostatic, electromagnetic, or magnetic fields.
Use static-protective packaging for shipping or storage.
STATIC-SENSITIVE
3.
APPLICATION GUIDELINES
The 3653–36 provides an interface between 600-ohm balanced 4-wire (4W) VF/DATA circuits and the 360/363
D4 Digital Carrier Terminal common equipment. The receive and transmit paths of the 3653–36 provide level con-
trols to accommodate TLP levels from –19.5 to +13.0 dBm. The 3653–36 also provides tone or manually acti-
vated loopback function that can eliminate the need for external loopback equipment. A typical application is
shown in Figure 2.
360/363 D4
DIGITAL
CARRIER
TERMINAL
T1/DS1
FACILITY
3653–36
4W TO/
ER/LB
T
R
T1
R1
D
A
T
A
4W TO/
ER/LB
3653–36
M
O
D
E
M
A
N
A-
L
O
G
360/363 D4
DIGITAL
CARRIER
TERMINAL
M
O
D
E
M
A
N
A
L
O
G
D
A
T
A
Figure 2. Typical 3653–36 4W TO/ER/LB Application
4.
CIRCUIT DESCRIPTION
Refer to Figure 3, the 3653–36 block diagram, as needed while reading the following circuit description.
4.1
Transmit VF Path
VF signals applied to the input T&R (pins 50 and 48) are routed through the DROP and LINE lifting jacks to trans-
former T1. Transformer T1 provides a balanced input and DC isolation from the line.
Voice energy from transformer T1 is routed to the XMT level control circuit.
The XMT level control provides a total of 32.5 dB of level control in 0.1 dB increments. Switches S2 and S3 asso-
ciated with this circuit allow the transmit port to accommodate a –19.5 to +13.0 dBm input TLP range.
The adjusted VF signal is then applied to the XMT FILTER circuit. The filter suppresses frequencies that are out-
side of the standard voice frequency and prevents them from entering the ENCODER. The ENCODER performs
an analog-to-digital (A/D) conversion and sends the resulting PCM signal to the 360/363 common equipment via
the XDATA lead.
4.2
Receive VF Path
The PCM digital signal from the far end is received by the 360/363 common equipment, is routed to the 3653–36
via the RDATA lead, and is applied to the DECODER circuit. The DECODER then performs a digital-to-analog
(D/A) conversion of the signal. The analog signal from the DECODER circuit is applied to the RCV FILTER. The
RCV FILTER suppresses frequencies that are outside the bandwidth of the standard voice band.
The output of the RCV filter is applied to the RCV level control. The RCV level control provides a total of 32.5 dB
of level control in 0.1 dB increments. Switches S4 and S5 allow the receive port to accommodate a –19.5 to
+13.0 dBm input TLP range.