Radio transmitter for modulating a carrier wave

• US 8,165,541 B2
• Filed: 06/12/2009
• Issued: 04/24/2012
• Est. Priority Date: 06/13/2008
• Status: Active Grant

• Current Assignee: Omron Automotive Electronics Company Limited (Nidec Corporation)
• Original Assignee: Omron Automotive Electronics Company Limited (Nidec Corporation)
• Inventors: Yamashita, Shuji, Tanaka, Akitomo, Kawashima, Hidemitsu, Hatakeyama, Yasushi
• Primary Examiner(s): VO, NGUYEN THANH
• Application Number:
  US12/483,893
• Publication Number:
  US 20090311977A1
• Time in Patent Office: 1,047 Days
• Field of Search: 455/91, 455/118, 455/120, 455/121, 455/125, 455/127.1, 455/127.2, 455/522, 340/10.1, 340/10.4, 375/295
• US Class Current: 455/118
• CPC Class Codes: B60C 23/0416 allocating a corresponding wheel position on vehicle, e.g. front/left or rear/right
• CPC Class Codes: B60C 23/0433 Radio signals

Abstract

A radio transmitter for modulating a carrier wave in a predetermined frequency with given information to transmit the modulation signal through an antenna having a predetermined resonance frequency f1 has a frequency changing section that changes the frequency of the carrier wave. The frequency changing section changes the frequency of the carrier wave to one of the resonance frequency f1 and a frequency f1×1/n, (wherein n is a given integer of at least 2, to change transmission output power.

Claims

1. A radio transmitter for modulating a carrier wave in a predetermined frequency with given information to transmit the modulation signal through an antenna having a predetermined resonance frequency f1, the radio transmitter comprising:

a frequency changing section that changes the frequency of the carrier wave,

wherein when the radio transmitter transmits the signal through the antenna, the frequency changing section sets the frequency of the carrier wave to a frequency of a harmonic wave f1 ×

1/n, wherein n is a given integer of at least 2, which is a harmonic order, to change transmission output power.

2. The radio transmitter according to claim 1, further comprising:

a duty setting section that sets, when the carrier wave is a rectangular waveform in which ON periods and OFF periods are repeated in predetermined cycles, a duty of occupation by one of the ON periods and OFF periods in one cycle of the waveform,

wherein the frequency changing section performs the operation for changing the transmission output power when the duty setting section sets a predetermined duty.