User`s guide

4-18 DL3100 User’s Guide—November 1998

¥ Transmit ClockÑInternal, Network and External (DefaultÑInternal).

Designates the T3 Transmit Main Clock source.

InternalÑCauses the internal timing source of the DL3100 to generate

the DS3 transmit timing. The receive timing is always recovered from

the incoming DS3 signal.

NetworkÑAllows the recovered receive timing to clock the transmit

signal (loop).

ExternalÑAllows a customer-supplied External 1.544 MHz clock source

to provide the DS3 clock. An External Clock BNC is provided on the

back of the DL3100 for this purpose.

¥ Current Transmit ClockÑInternal, Network and External

Read-only Þeld. Indicates the current clock source. This Þeld could be

different from the Transmit Clock Þeld if clock fallback occurs.

¥ T3MB Alarm ThresholdsÑBipolar Violations, P-bit Parity Errors, CP-bit

Parity Errors, and Frame Bit Errors

Lets you set the major and minor T3MB Alarm Thresholds.

You can change either the mantissa or the exponent of any of these

thresholds. As you cursor down or to the right or left, the highlight bar

will select only those elements in each threshold that are conÞgurable.

To change a mantissa or exponent, select it and type in the new value.

If you set different thresholds for these parameters, it is possible to get

two sets of C-bit or P-bit alarms. The PA R LED on the faceplate may

activate (due to the Bellcore requirements), while simultaneously,

alarms are generated (due to the customer set thresholds).

NOTE: If the network clock is lost, the unit will fall back to external

clock. If there is no external clock, the unit will fall back to the internal

clock. However, if the network clock or external clock becomes

available and the unit is conﬁgured for one of these, then the unit

reverts to the conﬁgured clock type.

NOTE: Though the P-bit and C-bit Parity Error thresholds can be set

through this screen, they are independent of the C-bit and P-bit

parameters which activate the PAR LED on the DL3100. These are

always set at 10-6, per Bellcore requirements.