Patent ID: 7724237

Claim:
A method of using a radio signal to identify a location of a hand-held printing device on a print media, comprising: receiving a first radio signal on a first antenna of the printing device, wherein the first radio signal comprises a varying frequency signal transmitted by a beacon; receiving a second radio signal on a second antenna of the printing device, wherein the second radio signal comprises a varying frequency signal transmitted by the beacon; determining a first zero-crossing frequency corresponding to the received first radio signal at a first time; determining a second zero-crossing frequency corresponding to the received second radio signal at a first time; receiving the first radio signal on the first antenna at a second time; determining a first zero-crossing frequency corresponding to the received first radio signal at the second time; receiving the second radio signal on the second antenna at a second time; determining a second zero-crossing frequency corresponding to the received second radio signal at the second time; and calculating a relative change in location of the printing device utilizing the determined first zero-crossing frequency and the second zero-crossing frequency at both the first and second times.