Generations of sequences of waveforms

• US 7,408,499 B2
• Filed: 07/06/2004
• Issued: 08/05/2008
• Est. Priority Date: 07/07/2003
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Szajnowski, Wieslaw Jerzy
• Primary Examiner(s): Sotomayor; John B
• Application Number:
  US10/563,132
• Publication Number:
  US 20060244653A1
• Time in Patent Office: 1,491 Days
• Field of Search: 342 70- 72, 342/108, 342/115, 342128-137, 342/145, 342/189, 342/195, 342200-204, 340/903, 340/435, 340/436, 701/301
• US Class Current: 342/70
• CPC Class Codes: G01S 13/106 using transmission of pulses having some particular characteristics G01S13/12, G01S13/22, G01S13/24, G01S13/26, G01S13/28 and G01S13/30 take precedence
• CPC Class Codes: G01S 13/30 using more than one pulse per radar period
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/9315 Monitoring blind spots
• CPC Class Codes: G01S 7/282 Transmitters

Abstract

A sequence of waveforms is generated by producing a primary symbol sequence and, for each symbol within the sequence, substituting a randomly-selected waveform. The primary symbol sequence has a narrow autocorrelation function, and may be a train of pulses, with the pulses arranged in packets of predetermined configuration. Objects can be detected by transmitting the waveforms, forming a representation of the transmitted waveform and delaying that representation, and correlating the representation with signals received as a result of reflection of the transmitted waveforms.

Claims

1. A method of generating a sequence of waveforms, wherein:

the waveforms are generated at timings corresponding to pulses in a primary sequence having a narrow autocorrelation sequence, said pulses being arranged in packets of predetermined configuration with gaps between the packets, and the timings of the pulses within each packet being such that each packet has a narrow autocorrelation sequence;

and wherein each waveform is randomly selected from a set of waveforms with respective predetermined characteristics.

2. A method as claimed in claim 1, wherein successive pulse packets are randomly selected from a predetermined set of pulse packets.

3. A method as claimed in claim 1, wherein the gaps between pulse packets are of randomly-selected length.

4. A method as claimed in claim 1, wherein the minimum gap between adjacent pulses in a packet exceeds a predetermined value, whereby the autocorrelation sequence of the packet exhibits a zero value for consecutive relative shifts which do not exceed a predetermined limit.

5. A method as claimed in claim 1, in which the waveforms of said set are substantially mutually orthogonal.

6. A method as claimed in claim 1, wherein the waveforms have respective different frequencies.

7. A method of generating a sequence of waveforms, each waveform being generated at a liming corresponding to that of a respective symbol in a primary sequence having a narrow autocorrelation sequence, the primary symbol sequence including symbols of a plurality of types, wherein each waveform is randomly selected from one of a plurality of sets of waveforms having respective predetermined characteristics, the set from which the waveform is selected being dependent on the type of the respective symbol.

8. A method as claimed in claim 7, in which the primary symbol sequence comprises a first pulse sequence interleaved with a second pulse sequence which is a time-reversed replica of the first pulse sequence, at least a substantial number of the waveforms corresponding to each pulse sequence being distinguishable from those corresponding to the other pulse sequence.

9. A method of generating a sequence of waveforms, the waveforms being generated at timings corresponding to symbols in a primary sequence having a narrow autocorrelation function, wherein each waveform is randomly selected from a set of waveforms with respective predetermined characteristics.

10. A method of detecting an object, the method comprising transmitting a sequence of waveforms generated using a method as claimed in claim 9, receiving reflections of the transmitted waveforms and determining matches between the transmitted and received waveforms.

11. A method as claimed in claim 10, wherein the transmitted waveforms are selected from sets each corresponding to a respective symbol type in the primary symbol sequence, the method including decoding the received waveforms to obtain a received symbol sequence and cross-correlating the primary symbol sequence with the received symbol sequence to determine matches between the transmitted and received waveforms.

12. A method as claimed in claim 10, including the step of storing data indicating which waveforms have been randomly selected, and using the stored data to determine matches between the transmitted and received waveforms.

14. Obstacle-detection apparatus for use in a multi-user environment, the apparatus being arranged to operate in accordance with a method as claimed in claim 10.

15. Obstacle-detection apparatus as claimed in claim 14, including means for providing a signal indicative of the range of a detected object.

16. Obstacle-detection apparatus as claimed in claim 14 for use in a vehicle or vessel to detect potential collisions.

17. A collision-warning system for a vehicle or vessel, the system comprising an obstacle-detection apparatus as claimed in claim 16 and means for generating a warning signal in response to obstacle detection.

18. A ranging aid for a vehicle or vessel, the system comprising an obstacle-detection apparatus as claimed in claim 16 and means for generating a signal indicative of the range of a detected obstacle.

13. Apparatus for generating a sequence of waveforms, the apparatus being arranged to operate in accordance with a method as claimed in 1.