US 6,982,557 B1
Cable tester
William Lo, Cupertino, Calif. (US); Yiqing Guo, Cupertino, Calif. (US); Tak Tsui, Sunnyvale, Calif. (US); Tsin-Ho Leung, San Jose, Calif. (US); Runsheng He, Sunnyvale, Calif. (US); and Eric Janofsky, Sunnyvale, Calif. (US)
Assigned to Marvell International, Ltd., Hamilton (Bermuda)
Filed on Nov. 02, 2004, as Appl. No. 10/979,302.
Application 10/979302 is a division of application No. 10/401221, filed on Mar. 27, 2003.
Application 10/401221 is a continuation in part of application No. 10/331221, filed on Dec. 30, 2002.
Application 10/331221 is a continuation in part of application No. 10/165467, filed on Jun. 07, 2002, granted, now 6,825,672.
Int. Cl. G01R 31/02 (2006.01)
U.S. Cl. 324—539 24 Claims
OG exemplary drawing
 
1. A physical layer device, comprising:
a cable tester that:
senses activity on a first pair of a cable and enables testing if activity is not detected for a first period;
enables testing of said first pair if, during said first period, activity is detected on said first pair and is subsequently not detected on said first pair for a second period after said activity is detected; and
generates a test pulse on the cable and determines a cable status including an open status, a short status, and a normal status when testing is enabled; and
a cable impedance estimator that communicates with said cable tester and that estimates an impedance of the cable based on a reflection amplitude of said test pulse.