T1 Pattern/Loop Screen

Access the test pattern screen by pressing the Pattern/Loop key, which includes 12 defined patterns and up to six user‑defined patterns. The user‑defined patterns can be created by pressing the Set User Pattern submenu key. Refer to “Set User Pattern”.

The available patterns are: QRSS, PRBS‑9(511), PRBS‑11(2047), PRBS‑15, PRBS‑20, PRBS‑23, All Ones, All Zeros, T1 Daly, 1 in 8, 2 in 8, 3 in 24, or one of six user‑defined patterns (labeled User Pattern 1 through User Pattern 6). The defined patterns are listed in Table: “Defined Test Patterns”.

Inverse patterns can be used. Loop codes can be selected and used as loop up or loop down.

Submenu keys for the Pattern/Loop Menu are described in “Select Pattern”. For a list of test pattern descriptions, refer to Table: “Defined Test Patterns” .

 

Defined Test Patterns

Pattern	Description	Application
QRSS	1,048,575 bit pattern	Simulates live traffic including both high and low-density sequences
1 IN 8	Eight bit pattern of a 1 and 7 zeros	Checks clock recovery on circuits optioned for B8ZS
2 IN 8	Eight bit pattern of 2 ones and 6 zeros	Used to determine correct optioning of AMI or B8ZS line coding
3 IN 24	24 bit pattern with 3 ones and 15 consecutive zeros. 12.5% ones density	Stresses AMI optioned circuits for minimum ones density and maximum consecutive zeros performance. Forces zero substitutions in B8ZS optioned circuits
ALL ONES	All ones sent as payload in a framed sequence	Stresses ability of circuit to operate under maximum power conditions
ALL ZEROS	All zeros sent as payload in a framed sequence	Checks for B8ZS optioning. Circuit will drop if optioned for AMI
T1-DALY	Framed 55 octet sequence which changes rapidly from high to low density	Stresses timing recovery and ability of automatic line build out and equalizer circuits to respond quickly to changing ones density
PRBS-9 (511)	511 bit pseudo‑random pattern	Test sub‑rate DDS circuits operating below 56 kb/s
PRBS-11 (2047)	2,047 bit pseudo‑random pattern	Test 56 kb/s DDS circuits
PRBS-15	32,767 bit pseudo‑random pattern. Generates up to 14 consecutive zeros and 15 consecutive ones	Tests to CCITT Recommendations O.151 and G.703. Provides maximum number of zeros for testing non‑B8ZS circuits
PRBS-20	1,048,575 bit pseudo‑random pattern. Generates up to 19 consecutive zeros and 20 consecutive ones	Used to test synchronous T1 circuits only
PRBS-23	8,388,607 bit pseudo‑random pattern. Generates up to 22 consecutive zeros and 23 consecutive ones	Used to test synchronous T1 circuits

 

 

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