Method and device for determining separation and relative speed of a distant object

• US 20030179128A1
• Filed: 03/04/2003
• Published: 09/25/2003
• Est. Priority Date: 10/10/2000
• Status: Active Grant

• Current Assignee: Smart Microwave Sensors GmbH
• Original Assignee: Smart Microwave Sensors GmbH
• Inventors: Meincke, Marc-Michael, Rohling, Hermann, Mende, Ralph
• Granted Patent: US 6,864,832 B2
• Time in Patent Office: Days
• US Class Current: 342/70
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/347 using more than one modulation frequency
• CPC Class Codes: G01S 13/348 using square or rectangular modulation, e.g. diplex radar for ranging over short distances
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/931 of land vehicles

Abstract

The determination of separation (R) and relative speed (v) of at least one object which is distant from an observation point can be achieved by sending electromagnetic signals from the observation point, with a frequency shift over a modulation range (f_Sweep), in the form of signal segments (A, B) during a measuring interval, with a frequency separation (f_Shift) from each other which are transmitted alternately, the echo signals from which are detected after reflecting from the object. The phase difference (Δφ) of the echo signals arising from each signal segment (A, B) is detected. Said determination occurs with short reaction time and high precision whereby the signal segments (A, B) are transmitted with a stepwise shift each time by a frequency step (f_Incr) over the modulation range (f_Sweep) and at least one sampled value for determination of the phase difference (Δφ) for each signal segment is taken.

Claims

1. A method for determining the distance (R) and relative speed (v) of at least one object remote from an observation point with the aid of electromagnetic signals, which are emitted from the observation point and whose frequency is shifted over a modulation range (f_Sweep) during a measuring interval, and which are in the form of signal sections (A, B) that are emitted alternately and exhibit a frequency spacing (f_Shift) from one another and whose echo signals are detected after reflection at the object, the phase difference (Δ

ψ

) of the echo signals originating from the respective signal sections (A, B) being determined, characterized in that the signal sections (A, B) are emitted shifted in steps over the modulation range (f_Sweep) by in each case one frequency step (f_Incr), and in that at least one sample is taken for each signal section to determine the phase difference (Δ

ψ

).

2. The method as claimed in claim 1, characterized in that the echo signals are evaluated by Fourier transformation and by determining the phase difference between the peaks occurring thereby that correspond to the frequency of the echo signals of the signal steps (A, B).

3. The method as claimed in claim 1 or 2, characterized in that a uniqueness of the measurement of the distance (R) and the speed (v) is created by a combination of the ambiguous measurements for distance (R), which depend on frequency (κ

) and phase difference (Δ

ψ

), on the one hand, and speed (v) on the other hand.

4. The method as claimed in one of claims 1 to 3, characterized in that the samples for the echo signals of the signal sections (A, B) of the signals shifted in frequency relative to one another are processed in a common analog channel and not separated from one another until after an analog-to-digital conversion.

5. The method as claimed in one of claims 1 to 4, characterized in that the spacing (ƒ

_Shift) between, two frequencies remains the same over the entire modulation range (ƒ

_Sweep).

6. The method as claimed in one of claims 1 to 5, characterized in that the shift is undertaken by one frequency step (ƒ

_Incr) for each emission of the signal sections (A, B) of the two frequencies.

7. The method as claimed in one of claims 1 to 6, characterized in that the frequency step (ƒ

_Incr) corresponds to double the spacing (ƒ

_Shift) between the two frequencies.

8. The method as claimed in one of claims 1 to 7, characterized in that the altinating signal sections (A, B) are emitted and received continuously.

9. The method as claimed in one of claims 1 to 7, characterized in that a temporal spacing is kept between the emission of a signal section (A) of one frequency and the emission of a signal section (B) of the other frequency.

10. The method as claimed in one of claims 1 to 9, characterized in that use is made of more than two signals that are emitted with alternating signal sections and mutually differing frequency.

11. An apparatus for determining the distance (R) and relative speed (v) of at least one object remote from an observation point with the aid of an electromagnetic transmitter for alternately emitting signals whose frequency is shifted over a modulation range (f_Sweep) during a measuring interval, and which are in the form of signal sections (A, B) that are emitted alternately and exhibit a frequency spacing (f_Shift) from one another, and with the aid of a receiver for receiving the signal sections reflected by the object, the receiver having a device for establishing the phase difference (Δ

ψ

) between the echo signals originating from the respective signal sections (A, B), characterized in that the signal sections (A, B) are emitted shifted in steps over the modulation range (f_Sweep) by in each case one frequency step (f_Incr), and in that at least one sample is taken in the receiver for each signal section to determine the phase difference (Δ

ψ

).

12. The apparatus as claimed in claim 11, characterized in that the receiver has a Fourier transformation stage and a downstream determining device for determining the phase difference between the peaks that are formed in the Fourier transformation stage and correspond to the frequency of the echo signals of the signal sections (A, B).

13. The apparatus as claimed in claim 11 or 12, characterized in that a uniqueness of the measurement of the distance (R) and the speed (v) is created in the receiver by a combination of the ambiguous measurements for distance, which depend on frequency (κ

) and phase difference (Δ

ψ

), on the one hand, and speed on the other hand.

14. The apparatus as claimed in one of claims 11 to 13, characterized by a common analog channel for processing the samples for the signal sections (A, B) of the signals shifted in frequency relative to one another, by an analog-to-digital converter following thereupon, and by following separate digital evaluation channels.

15. The apparatus as claimed in one of claims 11 to 14, characterized in that the spacing (ƒ

_Shift) between the two frequencies remains the same over the entire modulation range (ƒ

_Sweep).

16. The apparatus as claimed in one of claims 11 to 15, characterized in that the shift is undertaken by one frequency step (ƒ

_Incr) for each emission of the signal sections (A, B) of the two frequencies.

17. The apparatus as claimed in one of claims 11 to 16, characterized in that the frequency step (ƒ

_Incr) corresponds to double the spacing (ƒ

_Shift) between the two frequencies.

18. The apparatus as claimed in one of claims 11 to 17, characterized in that the alternating signal sections (A, B) are emitted and received continuously.

19. The apparatus as claimed in one of claims 11 to 17, characterized in that a temporal spacing is kept between the emission of a signal section (A) of one frequency and the emission of a signal section (B) of the other frequency.

20. The device as claimed in one of claims 11 to 19, characterized by an electromagnetic transmitter for emitting more than two signals in the form of alternating signal sections with mutually differing frequencies.