Patterns

---

Many test patterns are available to 'stress' the circuit in a unique way or to gain maximum insight into a particular problem. Much has been written to guide the troubleshooter to select the proper pattern. Below is a summary of the qualities of the patterns available in the test set.
1:7 - An eight-bit pattern that contains a single one. Used to test clock recovery.
2 in 8 - An eight bit pattern with two ones and a maximum of four consecutive zeroes. B8ZS is never sent.
3 in 24 - A twenty-four bit-pattern containing 3 ones with the longest length of consecutive zeroes constrained to fifteen. It has a ones density of 12.5% and is used to check clock recovery.
All 1's - A pattern that causes line drivers to consume the maximum amount of current. If framing is set to 'Unframed' the resulting pattern is equivalent to a 'Blue Alarm' or 'Alarm Indication Signal' or AIS.
All 0's - A pattern that is often selected to verify B8ZS provisioning.
QRSS - A pseudorandom pattern that simulates live traffic on a circuit. It is a very common test pattern
T1-DALY - A pattern that changes rapidly between high and low density. This pattern is used to stress ALBO, equalizer and timing recovery circuits.
55 Octet - Similar to the T1-DALY pattern except that it contains runs of fifteen consecutive zeroes that violate ones density requirements if sent unframed.
2E15-1 - A pseudorandom pattern based on a 15 bit shift register.
2E20-1 - A pseudorandom pattern based on a 20 bit shift register.
2E23-1 - A pseudorandom pattern based on a 23 bit shift register.
Alternating Ones and Zeroes - A pattern that alternates between ones and zeroes.