Radar distance sensor

• US 6,181,273 B1
• Filed: 07/12/1999
• Issued: 01/30/2001
• Est. Priority Date: 01/29/1997
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Heide, Patric, Nalezinski, Martin
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US09/341,502
• Time in Patent Office: 568 Days
• Field of Search: 342/130, 342/131, 342/129, 342/135, 342/132, 342/128
• US Class Current: 342/130
• 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 7/35 Details of non-pulse systems

Abstract

Microwave radar: an additional modulation of the microwave signal (s (t)) provided for the emission or of the reception signal (e (t)) makes it possible to separate the payload signal from the noise signal parts in a following demodulation and filter unit (HP, MI2, TP). To this end, a modulation unit (MO, RG) for suitably modulating the signal to be emitted is provided preceding the antenna (A). The undesired noise signals produced by the components of the radar sensor itself are not modulated and can therefore be separated from the payload signal by filtering. This separation ensues after a raw measured signal (mess'"'"' (t)) has been generated by mixing transmission and reception signal (MI). A renewed demodulation with the modulation signal (r t)) of the modulation unit supplies the final measured signal (mess2 (t)) determinant for the determination of the distance, whereby the noise signals are previously removed by high-pass filtering and/or are subsequently removed by low-pass filtering.

Claims

1. An apparatus for distance measurement, comprising:

a signal source for generating a frequency-modulated microwave signal;

an antenna arrangement for emitting the microwave signal and for receiving a signal reflected at an object;

a modulation unit for additionally modulating the microwave signal provided for emission and/or the reflected signal with a modulation signal;

a mixer for generating a mixed product of the microwave signal generated by the signal source and the reflected signal modulated by the modulation unit; and

a demodulation and filter unit for removing a portion of the mixed product that lies below a lowest frequency of the modulation signal with a filter and for processing a remaining part of the mixed product by mixing with the modulation signal to form a measured signal;

the antenna arrangement being composed of an antenna that is provided for transmission and reception;

a transmission/reception diplexer for conducting the microwave signal from the signal source to the antenna and for conducting the reflected signal from the antenna to the demodulation and filter unit; and

the modulation unit has a bidirectional modulator that is arranged between this transmission/reception diplexer and the antenna.

2. The apparatus according to claim 1, wherein the modulation signal effects a phase modulation with a phase boost of 180°

.

3. The apparatus according to claim 1,

wherein the modulation and filter unit have a high-pass filter and a further mixer;

wherein the high-pass filter is arranged between the mixer and this further mixer; and

wherein the further mixer is arranged such that the further mixer mixes the signal coming from the high-pass filter with the modulation signal.

4. The apparatus according to claim 1,

wherein the demodulation and filter unit has a low-pass filter and a further mixer;

the further mixer being arranged such that the further mixer mixes the signal coming from the mixer with the modulation signal; and

wherein the signal supplied by the further mixer is supplied to the low-pass filter.