Radar device

• US 7,486,225 B2
• Filed: 09/24/2007
• Issued: 02/03/2009
• Est. Priority Date: 11/25/2003
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Mikami, Satoshi, Sueya, Masayoshi
• Primary Examiner(s): Sotomayor; John B
• Application Number:
  US11/902,651
• Publication Number:
  US 20080180311A1
• Time in Patent Office: 498 Days
• Field of Search: 342 70- 72, 342/21, 342 82-103, 342107-116, 342128-135, 342/145, 342/152, 342/159, 342173-174, 342194-195, 375/1, 375130-153
• US Class Current: 342/109
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop

Abstract

A data code generator produces a data code, while a reference code generator produces a reference code. The data code is phase-shifted by the data code generator in a predetermined sweep range, according to a sweep command signal given by a phase difference detector. The phase difference detector compares the phase of the data code with that of the reference code to obtain phase difference data. Based on the phase difference data, a correction signal generator produces a correction signal to keep the data code in phase with the reference, code. The phase setter optimizes the phase of the data code according to the correction signal.

Claims

1. A radar device that detects an object, comprising:

(a) a spreading code generator device, comprising;

a reference code generator that generates a reference code,

a phase corrector that produces a sweep command signal for use in shifting the phase of a spreading code in a predetermined sweep range, compares the phase of the spreading code being shifted with the phase of the reference code to obtain phase difference data, and produces a correction signal based on the phase difference data to keep the spreading code in phase with the reference code, and

a spreading code generator that shifts the spreading code in response to the sweep command signal, optimizes the phase of the spreading code according to the correction signal and produces the spreading code while varying its phase offset;

(b) a radio wave signal transmitter that produces a radio wave signal by modulating a carrier wave with the reference code and emits the radio wave signal;

(c) a radio wave signal receiver that receives the radio wave signal reflected by an object and demodulates the received radio wave signal into an in-phase component and a quadrature component;

(d) a correlation detector that produces correlation-detected values by performing correlation detection of the in-phase and quadrature components using the spreading code; and

(e) a speed/distance detector that calculates power of correlation-detected values to determine a distance to the object and a speed of the object.

2. The radar device according to claim 1, wherein said phase corrector determines a code error rate of the spreading code being shifted in the sweep range by comparing the spreading code with the reference code and outputs the code error rate at each sweep position as the phase difference data.

3. The radar device according to claim 2, wherein:

a threshold is defined for the number of code errors detected;

said phase corrector produces the sweep command signal only within a part of the sweep range where the number of code errors detected is below the threshold.

4. The radar device according to claim 1, wherein said phase corrector comprises a mixer that mixes the spreading code with the reference code to determine correlation therebetween in the sweep range and outputs the resulting correlation value at each sweep position as the phase difference data.