Rangefinder

• US 6,052,080 A
• Filed: 03/09/1998
• Issued: 04/18/2000
• Est. Priority Date: 09/07/1995
• Status: Expired due to Term

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Magori, Valentin
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US09/029,911
• Time in Patent Office: 771 Days
• Field of Search: 342/118, 342/122, 342/128, 342/129
• US Class Current: 342/118
• 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 7/023 Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36
• CPC Class Codes: G01S 7/352 Receivers
• CPC Class Codes: G01S 7/4021 of receivers

Abstract

For improving the measuring precision, a reference unit (REF) is juxtaposed with a continuous wave radar (DSR). This reference unit (REF) comprises a surface wave element (OFW) for generating a signal delayed relative to the transmission signal. A mixed signal is formed from the delayed signal and the transmission signal with a mixer (MI2), this mixed signal being utilized in combination with the measured signal stemming from the continuous wave radar (DSR) for determining the distance.

Claims

1. Apparatus for distance measurement,

wherein a signal source (SQ) is present for generating a frequency-modulated signal,

wherein a transmission/reception stage (SES) and a first mixer (MI1) are present,

wherein this first mixer is arranged such that it can mixer a signal coming from the transmission/reception stage with the signal generated by the signal source,

wherein a reference unit (REF) is present that comprises a surface wave element (OFW) and a second mixer (MI2) and that is provided for delaying the signal coming from the signal source in terms of time and mixing it with the undelayed signal,

wherein an evaluation unit (AE) is present that is arranged such that the signals formed by the mixers are supplied to it, and

wherein this evaluation unit is configured for

a) determining the frequency characteristic of the signal stemming from the second mixer from said signal dependent on the time for arbitrarily prescribed test subject distances, and

b) determining the test subject distance with best coincidence by a comparison of these frequency characteristics to a signal stemming from the first mixer by correlation of evaluation according to the least error square.

4. Apparatus according to one of the claims 1 through 3, wherein a local oscillator and a further mixer (MIL) are present between the signal source and the transmission/reception stage, wherein the local oscillator generates a signal with a frequency that is higher than the frequency stemming from the signal source, and wherein the further mixer is provided for mixing the signal of the signal source with the signal of the local oscillator.

2. Apparatus for distance measurement,

wherein a signal source (SQ) is present for generating a frequency-modulated signal,

wherein a transmission/reception stage (SES) and a first mixer (MI1) are present,

wherein this first mixer is arranged such that it can mixer a signal coming from the transmission/reception stage with the signal generated by the signal source,

wherein a reference unit (REF) is present that comprises a surface wave element (OFW) and a second mixer (MI2) and that is provided for delaying the signal coming from the signal source in terms of time and mixing it with the undelayed signal,

wherein an evaluation unit (AE) is present that is arranged such that the signals formed by the mixers are supplied to it, and

wherein this evaluation unit is configured for

a) sampling a signal stemming from the first mixer at points in time of specific phase angles of the signal stemming from the second mixer,

b) digitizing the sampled values and storing them together with the points in time of the occurrence of the samples, and

c) acquiring a signal that would have derived given a linear frequency modulation, acquiring said signal by reading out the values with constant clock rate.

3. Apparatus for distance measurement,

wherein a signal source (SQ) is present for generating a frequency-modulated signal,

wherein a transmission/reception stage (SES) and a first mixer (MI1) are present,

wherein this first mixer is arranged such that it can mixer a signal coming from the transmission/reception stage with the signal generated by the signal source,

wherein a reference unit (REF) is present that comprises a surface wave element (OFW) and a second mixer (MI2) and that is provided for delaying the signal coming from the signal source in terms of time and mixing it with the undelayed signal,

wherein an evaluation unit (AE) is present that is arranged such that the signals formed by the mixers are supplied to it, and

wherein this evaluation unit is configured for

a) acquiring and storing the signals stemming from the mixers with a constant sampling rate,

b) calculating points in time with predetermined phase angles of the signal stemming from the second mixer,

c) determining the appertaining values of the signal stemming from the first mixer at these points in time, and

d) acquiring a signal that would have derived given a linear frequency modulation, acquiring said signal by reading out the values with a constant clock rate.

5. Method for distance measurement,

whereby a frequency-modulated signal is generated,

whereby the generated signal is beamed out and a part of the signal reflected by a test subject is received,

whereby the received signal is mixed with the generated signal to form a measured signal,

whereby the generated signal is mixed with a signal delayed in time relative thereto to form a reference signal,

whereby the frequency characteristic of the reference signal is determined dependent on the time for arbitrarily prescribed test subject distances, and

whereby these frequency characteristics are compared to a measured signal and the test subject distance of best coincidence is determined by correlation or evaluation according to the least error square.

6. Method for distance measurement,

whereby a frequency-modulated signal is generated,

whereby the generated signal is beamed out and a part of the signal reflected by a test subject is received,

whereby the received signal is mixed with the generated signal to form a measured signal,

whereby the generated signal is mixed with a signal delayed in time relative thereto to form a reference signal,

whereby a measured signal is sampled at points in time of specific phase angles of the reference signal,

whereby the sampled values are digitized and stored together with the points in time of the occurrence of the samples, and

whereby a signal that would have derived given a linear frequency modulation is acquired by readout of the values with a constant clock rate.

7. Method for distance measurement,

whereby a frequency-modulated signal is generated,

whereby the generated signal is beamed out and a part of the signal reflected by a test subject is received,

whereby the received signal is mixed with the generated signal to form a measured signal,

whereby the generated signal is mixed with a signal delayed in time relative thereto to form a reference signal,

whereby the measured signal and the reference signal are acquired with constant sampling rate and stored,

whereby points in time with predetermined phase angles of the reference signal are calculated,

whereby the appertaining values of the measured signal are determined at these points in time, and

whereby a signal that would have derived given a linear frequency modulation is acquired by readout of the values with a constant clock rate.