XRT73L04A
4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT
REV. 2.0.3
36
3.0
THE RECEIVE SECTION
Figure 13 indicates the Receive Section consists of
the following blocks:
• AGC/Equalizer
• Peak Detector
• Slicer
• Clock Recovery PLL
• Data Recovery
• HDB3/B3ZS Decoder
The purpose of the Receive Section is to take an in-
coming attenuated/distorted bipolar signal from the
line and encode it back into the TTL/CMOS format
where it can be received and processed by the Termi-
nal Equipment.
3.1
I
NTERFACING
THE
R
ECEIVE
S
ECTIONS
OF
THE
XRT73L04A
TO
THE
L
INE
The design of the Receive Circuitry allows for trans-
former-couple or capacitive-couple the Receive Sec-
tion to the line. The specification documents for E3,
DS3, and STS-1 all specify 75 Ohm termination loads
when transmitting over coaxial cable. The recom-
mended method to interface the Receive Section to
the line in a manner is shown in Figure 22 and Figure
23.
Figure 23 presents the recommended schematic for
capacitive-coupling each Receive Section of the
XRT73L04A to the line.
F
IGURE
22. R
ECOMMENDED
S
CHEMATIC
FOR
I
NTERFACING
THE
R
ECEIVE
S
ECTION
OF
THE
XRT73L04A
TO
THE
L
INE
(T
RANSFORMER
-C
OUPLING
)
J1
BNC
T1
1:1
R1
37.4
Ω
R2
37.4
Ω
Channel (n)
RxPOS_(n)
RxNEG_(n)
RxClk_(n)
RTIP_(n)
RRing_(n)
RPOS_(n)
RNEG_(n)
RxClk_(n)
C1
0.01uf
Only One Channel Shown
F
IGURE
23. R
ECOMMENDED
S
CHEMATIC
FOR
I
NTERFACING
THE
R
ECEIVE
S
ECTION
OF
THE
XRT73L04A
TO
THE
L
INE
(C
APACITIVE
-C
OUPLING
)
R1
75
Ω
J1
BNC
Channel (n)
RxPOS_(n)
RxNEG_(n)
RxClk_(n)
RTIP_(n)
RRing_(n)
RPOS_(n)
RNEG_(n)
RxClk_(n)
C1
0.01uf
Only One Channel Shown
C2
0.01uf
