DS_1x22_017
73M1822/73M1922 Data Sheet
13 Loopback and Testing Modes
Figure 36 show the five loopback modes available in the 73M1x22.
73M1822 HIC/
73M1902
73M1822 LIC/
73M1912
CTL
STA
STA
Ring
Buffer
Aux A/D
Tip
Onchip
PRP
SCP
LIC
Interp.
Filter
TxA
DSDM
LSBI
MSBI
TxAFE
TxD
TxD
RxD
TBS
RBS
TxData
RxData
External
LIC
DIGLB1
MAFE
Interface
ALB
DIGLB2
INTLB1
INTLB2
RxAFE
Decim.
Filter
SinC3
Filter
RxD
RxA
PRM
SCM
Ring
Figure 36: Loopback Modes Highlighted
Table 47 describes how the above control bits interact to provide each of the six loopback modes.
Table 47: Loopback Modes
TEST
TMEN
DTST Loopback Mode
Mnemonic
Normal mode. (Default)
No Loops
0000
0
00
Digital Loopback mode. Interpolated
TxData (TxD) is looped back to the
Decimated RxData input (RxD).
DIGLB1
0000
0000
1
1
10
Remote Analog Loopback. Received RxD INTLB1
is looped back as TxD and transmitted
back to the 73M1922
11
Line-Side Device; RxD is D/A converted to
yield the analog transmit signal (TxA).
Digital Loopback mode. Transmit Bit
Stream (TBS) is looped back to receive
digital channel and received (DIGLB2).
DIGLB2
INTLB2
0001
0010
0011
0
0
0
00
00
00
Remote Analog Loopback. Receive
analog signal is converted to Received Bit
Stream (RBS) and is looped back to TBS
and the analog transmit channel (INTLB2).
Analog Loopback. The transmit data is
connected to the receiver at the analog
interface and received (ALB).
ALB
Rev. 1.6
75
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