Operating Basics
GTS1063 and GTS1250 GBIC Test Systems Instruction Manual
15
This section describes each transmit-side signal.
Tx DATA and Tx DATA OUT.
These 50
W
, AC coupled, ~ECL/2 level signals match
what is being sent to the GBIC transmitter. Digital polarity is maintained with
the digital differential polarity of the signal being sent to the GBIC.
Tx CLK OUT.
This 50
W
, AC coupled, ~ECL/2 level, 1.25 GHz (GTS1250) or
1.0625 GHz (GTS1063) clock signal is synchronous with the outgoing trans-
mitted signal. When EXT mode is selected, this output is disabled.
SYNC OUT.
This 50
W
, AC-coupled, ~ECL/2 level signal is synchronous to and at
the framerate of the outgoing pattern. When EXT mode is selected, this output is
disabled. Use this Sync pulse to trigger an oscilloscope at a rate slower than the
data rate of the pattern, thereby allowing you to capture the individual 1s and 0s
of the entire pattern (as opposed to seeing an eye-pattern when equivalent-time
sampling using a trigger signal with a rep rate higher than the pattern data rate).
The repetition rate of this Sync pulse depends on the specific pattern selected
(see Tx SYNC Out pulse on page 30).
EXT DATA IN.
This is an input through which you can supply an NRZ, AC-
coupled, 50
W
data signal to digitally modulate the GBIC transmitter (EXT
mode must be selected). When in EXT mode, a signal input to this connector is
digitally received, buffered, and routed to the electrical differential data outputs
as well as the differential inputs of the GBIC. The logical polarity of the signal is
maintained. When not in EXT mode, the input signal is ignored.
NOTE
. To minimize noise from this input, do not connect a signal to this
connector when using an internal Tx Pattern.
The GBIC Test System monitors the flags coming from the GBIC Port receptacle
(Rx_LOS and Tx_FAULT). In general, if the TX_FAULT signal is high, then the
Tx FAULT LED is illuminated. Similarly, if the RX_LOS signal is high, then the
Rcv LOS LED is illuminated. These signals and their definition are discussed in
more detail in GBIC Flags on page 19. During an overload of the GBIC port
receptacle supplies, these indicators blink (see GBIC Overload Indicators on
page 16 for more information).
NOTE
. When no GBIC is installed, both the Rcv LOS and Tx FAULT indicators
are illuminated.
Transmit Signals
Tx Fault and Rx LOS
Indicators
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