Signaling Type Key; Tx Clk Source Key (Quickbert-T1 Only); Loop Code Key (Quickbert-T1 Only) - Fluke 635 User Manual

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Users Manual

2-17. SIGNALING TYPE Key

When the test set is in frame sync, either the D4, ESF, or SLC96 green
Framing LED illuminates. For further analysis, the unit provides the ability to
view the state of the signaling bits and data bits for a selected DS0 channel.
There are four yellow Signaling Bits LEDs provided for this purpose (A, B, C,
D). The D4 and SLC96 framing modes make provision for two signaling bits
(A, B). The ESF framing mode makes provision for four signaling bits (A, B,
C, D). In order to display the state of the signaling bits, the test set must be set
up for the proper signaling format (robbed bit, CCIS, or E-Bit) being used on
the T1 line under test.
The robbed bit (RB) scheme uses "robbed" data bits to transmit the signaling
states. In common channel interoffice signaling (CCIS), a complete channel
(DS0) is used to transmit signaling bits, thus leaving the eight data bits
available to transmit data (clear channel). The E-Bit selection is provided to
define a proprietary common channel signaling scheme.

2-18. TX CLK SOURCE Key (QuickBERT-T1 only)

This key is used to select one of three transmit clock sources: Rx (recovered),
Int (internal), and Ext (external). When Rx is selected, the QuickBERT-T1
recovers the clock from the received bit stream and uses the received clock as
the timing element for the transmit data. When Int is selected, the 1.544 MHz
internal oscillator is used to clock the transmitter. When Ext is selected, the
QuickBERT-T1 recovers the bipolar clock from the external clock that is
applied to the REF bantam jack and uses this clock as the transmit timing
element.

2-19. LOOP CODE Key (QuickBERT-T1 only)

This key is used to select the type of loop code to be transmitted by the
QuickBERT-T1. See Table 2-1 for a list of the codes transmitted by the
QuickBERT-T1 when the corresponding selections are made and the SEND
LOOP UP or SEND LOOP DOWN key is pressed. The HDSL loop codes are
either ADTRAN, Inc. or PairGain Technologies, Inc. loop codes. Sections 2-20
through 2-37 provide detailed descriptions of the loop-code types.
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