Measurement of round trip latency in write and read paths

Details Measurement of round trip latency in write and read paths Measurement of round trip latency in write and read paths

2011-01-25

2011-01-25

Negrón, Daniell L (Department: 2627)

Dynamic magnetic information storage or retrieval

General processing of a digital signal

Data clocking

C360S046000

Reexamination Certificate

active

07876517

ABSTRACT:
A method and apparatus for measuring latency in a communication path is provided. The technique includes driving a signal such as a square wave on the communication path, such as a write path such that it travels around the write-read path, and sensing a returned signal at one end of the write-read path. A square wave signal corresponding to the square wave driven on the write path is delayed by a predetermined phase thus generating a delayed signal. The returned signal and the delayed signal are mixed, producing a mixed signal. The mixed signal is integrated to obtain an integrated output. The phase by which the delayed signal is shifted is successively adjusted. Returned signals are mixed with such delayed signals until the integrated output is equal to zero. The phase shift amount that results in a nulled integrated output, less a quarter cycle of the square wave, is equal to the round trip latency of the write-read path.

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