Signal acquisition detection method
AssigneeAT&T Corp.
InventorsGregory T. Brauns, Ramasubramaniam Ramachandran
Life of this patent
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Abstract
A method of detecting whether a valid DS1 signal is being received by a receiver. If the receiver does not have a valid signal (loss of signal), then the receiver reads consecutive fixed sized N bit blocks of the received digital signal. Each of the blocks or windows is checked for minimum 1s density. Received consecutive 0s are counted and checked against a maximum. If two sequential blocks of bits satisfy the 1s and consecutive 0s tests, then the received signal is judged valid and an acquisition of signal flag is asserted.
Claims6
An apparatus responsive to a digital signal for determining if the digital signal is valid by implementing a method of determining if the digital signal is valid, the method being CHARACTERIZED BY THE STEPS OF:
- A. reading a bit from the digital signal, the bit having a first state or a second state complementary to the first state;
- B. incrementing a first counter as each consecutive first state bit is read;
- C. incrementing a second counter and resetting the first counter as each second state bit is read;
- D. repeating steps A, B and C for N bits;
- E. setting a flag to indicate that a valid digital signal has been received when the first counter is less than a first predetermined number and the second counter is equal to or greater than a second predetermined number;
- and then
- F. clearing the second counter.
Dependencies are inferred from the claim text.