| US 7,499,444 B2 | ||
| Method for clock synchronization of wireless 1394 buses for nodes connected via IEEE 802.11 a/b WLAN | ||
| Jeff Bennett, Briarcliff Manor, N.Y. (US) | ||
| Assigned to Koninklijke Philips Electronics N.V., Eindhoven (Netherlands) | ||
| Appl. No. 10/561,474 PCT Filed Jun. 24, 2004, PCT No. PCT/IB2004/051004 § 371(c)(1), (2), (4) Date Dec. 20, 2005, PCT Pub. No. WO2004/114563, PCT Pub. Date Dec. 29, 2004. |
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| Claims priority of provisional application 60/482654, filed on Jun. 26, 2003. | ||
| Prior Publication US 2007/0110023 A1, May 17, 2007 | ||
| Int. Cl. H04J 3/06 (2006.01); H04B 7/212 (2006.01); H04B 7/00 (2006.01); H04Q 7/20 (2006.01) | ||
| U.S. Cl. 370—350 [370/503; 370/324; 455/502; 455/507] | 17 Claims |
| 1. A method for clock synchronization of a plurality of wireless devices that are in communication with respective nodes,
wherein at least some of the respective nodes are attached to different buses, comprising:
synchronizing an internal time base of a wireless master device attached to a first bus by receiving a Software Beacon Alert
that indicates a time of a subsequent transmission and applying the Software Beacon Alert to a first phase-lock loop circuit
associated with the master device to create a filtered Software Beacon Alert, wherein said first phase-lock loop circuit uses
a phase detector with an asymmetrical gain about zero error;
receiving a timing message transmitted from the master device on the first bus to a second phase-lock loop circuit associated
with at least one slave device attached to a second bus; and
providing the timing message from the second phase-locked loop to said at least one slave device attached to said a second
bus before the master device receives a subsequent Software Beacon Alert message, so that the wireless master device and the
at least one slave device are synchronized.
|