FMCW sensor
First Claim
Patent Images
1. An FMCW sensor comprising:
- a fixed frequency generator for generating a carrier frequency and having an output;
a second frequency generator for generating variable modulation frequencies and having an output;
a mixer for generating mixed signals from said carrier frequency and said modulation frequencies and for reducing said generated mixed signals to a predetermined frequency band, said mixer including a field effect transistor having a gate terminal connected to said output of said fixed frequency generator, a source terminal connected to ground, and a drain terminal connected to said output of said second frequency generator, and including an output, said mixed signals being supplied from said drain terminal to said output;
a transmitter and receiver unit having an input connected to said output of said mixer and having an output;
a reference unit having an input connected to said output of said second frequency generator and having an output; and
an evaluation means having an input connected to said output of said transmitter and receiver unit, an input connected to said output of said reference unit, and an output.
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Abstract
An FMCW sensor in which a transmission signal is generated from a high frequency of a fixed frequency oscillator and a modulated, low frequency of a second oscillator. The modulated frequency is processed in a delay line with a surface wave component to form a reference signal. A transmission mixer with a hybrid coupler having a 90° phase difference and terminated by diodes is employed in a transmission/reception means. A measured signal from the transmission mixer together with the reference signal is interpreted in an evaluation means.
31 Citations
11 Claims
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1. An FMCW sensor comprising:
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a fixed frequency generator for generating a carrier frequency and having an output;
a second frequency generator for generating variable modulation frequencies and having an output;
a mixer for generating mixed signals from said carrier frequency and said modulation frequencies and for reducing said generated mixed signals to a predetermined frequency band, said mixer including a field effect transistor having a gate terminal connected to said output of said fixed frequency generator, a source terminal connected to ground, and a drain terminal connected to said output of said second frequency generator, and including an output, said mixed signals being supplied from said drain terminal to said output;
a transmitter and receiver unit having an input connected to said output of said mixer and having an output;
a reference unit having an input connected to said output of said second frequency generator and having an output; and
an evaluation means having an input connected to said output of said transmitter and receiver unit, an input connected to said output of said reference unit, and an output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
wherein said transmitter and receiver unit is for monostatic operation and further comprises: a transmission mixer including a first input connected to said mixer, a second input, an output, and a hybrid coupler having a first output attached to a first coupling arm and a second output attached to a second coupling arm, said first and second coupling arms having a phase difference of 90°
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an antenna connected to said second input of said transmission mixer;
at least one non-linear component terminating at least one of said first and second outputs of said hybrid coupler; and
wherein said evaluation means is connected to said output of said transmission mixer.
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4. The FMCW sensor according to claim 3, wherein said at least one non-linear terminating component is a field effect transistor having a source terminal and a drain terminal connected to each other.
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5. The FMCW sensor according to claim 3, wherein said hybrid coupler comprises a first output attached to a first coupling arm, a second output attached to a second coupling arm, said first and second coupling arms having a phase difference of 180°
- , and a circuit element for effecting a phase shift of 90°
arranged in one of said first and second coupling arms.
- , and a circuit element for effecting a phase shift of 90°
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6. The FMCW sensor according to claim 3, wherein said first input of said transmission mixer is connected to said mixer via at least one further circuit element.
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7. The FMCW sensor according to claim 1, wherein said reference unit is a delay line for generating a reference signal that is time-delayed compared to said transmission signal.
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8. The FMCW sensor according to claim 7, wherein said reference unit comprises a surface wave component and a second mixer.
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9. The FMCW sensor according to claim 1, further comprising a following frequency filter is connected between said mixer and said transmitter and receiver unit for reducing said generated mixed signals to a predetermined frequency band.
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10. An FMCW sensor comprising:
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a fixed frequency generator for generating a carrier frequency and having an output;
a second frequency generator for generating variable modulation frequencies and having an output;
a mixer for generating mixed signals from said carrier frequency and said modulation frequencies and for reducing said generated mixed signals to a predetermined frequency band, said mixer including a field effect transistor having a gate terminal connected to said output of said second frequency generator, a source terminal connected to ground via a low pass filter, and a drain terminal connected to said output of said fixed frequency generator, and including an output, said mixed signals being supplied from said source terminal to said output;
a transmitter and receiver unit having an input connected to said output of said mixer and having an output;
a reference unit having an input connected to said output of said second frequency generator and having an output;
an evaluator having an input connected to said output of said transmitter and receiver unit, an input connected to said output of said reference unit, and an output. - View Dependent Claims (11)
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Specification