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voltage between the two test points labeled CURRENT or VOLTAGE. The voltage should be 0.6 VDC +/- 0.03 volts to

equal 60ma.

NOTE:

Current measurement test is not required when the span is fiber out to the customer site and the smartjack is

located in the same bay or adjacent bay as the mux and is locally powered by the same power plant as the

mux.

5.3. QRSS (Quasi Random Signal Sequence) TEST PATTERN

This pseudo-random sequence is based on a 20-bit shift register and generates every possible combination of 20-bits

(except all zero) and repeats every 1,048,756 bits. Before transmission into the network, this sequence is limited to 14

zeros so that it meets the 15-zero limitation when framed. The sequence has an average ones density of 50 percent.

This pattern is good for simulating traffic in a T1 system and has been shown to be similar in spectral content to voice

traffic.

Table 6: QRSS TEST PATTERN FOR AMI AND B8ZS LINE CODING

Pattern Average Ones Dens-

ity

Maximum Zeros Circuit Stressed

QRSS (un-framed) 50% 14 Timing and Equalization

QRSS (framed) 50% 15 Timing and Equalization

5.4. 1 in 8 PATTERN (also known as 1:7)

This pattern stresses the minimum ones density requirement for repeaters. This pattern will help determine if a timing

recovery problem exists with low-density patterns. When framed, the bits that are ones must be located in the second

bit position of each byte within the frame or a yellow alarm will occur. This test pattern is used to test the minimum ones

density for a B8ZS line code.

. . . 00 F 01000000 01000000 01000000 01. . .

AT&T Practice ATT-TP-000-000-006

Issue 1, 08/25/06

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