Telecommunications Techniques Corporation interceptor 147, Reference Manual, Page: 25 / 280

Instrument Description
2-7
2
INTERCEPTOR 147 2 Mbit/s and Data Analyzer
2.4 EXTERNAL CLOCK
The EXTERNAL CLOCK connector is a 75
Ω
BNC
unbalanced connector (or an optional 1.6/5.6 mm
connector) that is used to connect the test instrument to an
external clock source. When the external clock source is
selected, transmit timing is provided by the source that
you connect to the test instrument. The external clock may
also be used as a reference signal to compare timing to that
of the signal under test for slip measurements.
NOTE: The EXTERNAL CLOCK
connector is present only if
Option 147-1 is installed.
2.5 DATA INTERFACE SIGNALING LEDS
When you perform a Data test, the DATA INTERFACE
LEDs illuminate to indicate whether the test instrument is
configured to emulate a DTE or a DCE, and to indicate
which control signals are active on the receive side. For
X.21, the C lead is indicated by the RS LED, and the I lead
is indicated by the CS LED.
75
Ω
2M REF
EXTERNAL CLOCK
EMULATE
DTE EMULATE
DCE *
CCITT
V.11
X.21 V.24
V.35
106
107
109
142
CS
DM
RR
TM
CTS
DSR
RLSD
TM
CCITT
105
108
141
140
RS
TR
LL
RL
RTS
DTR
LL
RL
* USE WITH DCE CABLE ADAPTER
DATA INTERFACE
V.11
X.21 V.24
V.35