Radar
AssigneeMurata Manufacturing Co., Ltd.
InventorSadao Yamashita
Life of this patent
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Abstract
In a radar, a frequency-modulated transmission signal whose frequency varies in time is generated. The gain-frequency characteristics of an IF signal which represents a beat signal between the transmission signal and a reception signal has its peak at or below one half of the sampling frequency of an AD converter. The gain-frequency characteristics of an IF amplifier circuit is determined so that the gain increases as the frequency increases at or below the frequency corresponding to the peak, the ratio of change in the gain relative to change in the frequency becomes smaller at short distances for which a saturation of a mixer is caused, and the gain is reduced at DC and in the vicinity of DC.
Claims16
A radar for detecting the distance to a target based on the frequency difference between a transmission signal and a reception signal, said radar comprising:
- a transmission circuit for generating a frequency-modulated transmission signal whose frequency varies in time;
- a mixer circuit for generating an IF signal as an output signal representing the frequency difference between the reception signal and the transmission signal;
- an amplifier circuit for amplifying the IF signal, the gain thereof having its peak at or below one half of a predetermined sampling frequency of an AD converter coupled to an output of the amplifier circuit;
- and
- the AD converter sampling the IF signal at the predetermined sampling frequency and converting the IF signal from an analog signal to a digital signal.
A radar for detecting the distance to a target based on the frequency difference between a transmission signal and a reception signal, said radar comprising:
- a transmission circuit for generating a frequency-modulated transmission signal whose frequency varies in time;
- a mixer circuit for generating an IF signal as an output signal representing the frequency difference between the reception signal and the transmission signal;
- an amplifier circuit for amplifying the IF signal;
- a DC blocking circuit provided at an input of said amplifier circuit;
- and
- an offset circuit for adding a predetermined DC offset, provided at the output of said amplifier circuit.
A radar for detecting the distance to a target based on the frequency difference between a transmission signal and a reception signal, said radar comprising:
- a transmission circuit for generating a frequency-modulated transmission signal whose frequency varies in time;
- a mixer circuit for generating an IF signal as an output signal representing the frequency difference between the reception signal and the transmission signal;
- an amplifier circuit for amplifying the IF signal, the gain thereof having its peak at or below one half of a predetermined sampling frequency of an AD converter coupled to an output of the amplifier circuit;
- the AD converter sampling the IF signal at the predetermined sampling frequency and converting the IF signal from an analog signal to a digital signal;
- a first DC blocking circuit provided at an input of said amplifier circuit;
- a second DC blocking circuit provided at the output of said amplifier circuit;
- and
- an offset circuit, provided at the output of said amplifier circuit, for adding a predetermined DC offset to a signal from which DC component has been removed by said second DC blocking circuit.
A radar for detecting the distance to a target based on the frequency difference between a transmission signal and a reception signal, said radar comprising:
- a transmission circuit for generating a frequency-modulated transmission signal whose frequency varies in time;
- a mixer circuit for generating an IF signal representing the frequency difference between the reception signal and the transmission signal;
- an amplifier circuit for amplifying the IF signal, the gain thereof having its peak at or below one half of a predetermined sampling frequency of an AD converter coupled to an output of the amplifier circuit;
- and
- the AD converter sampling the IF signal at the predetermined sampling frequency and converting the IF signal from an analog signal to a digital signal, said amplifier circuit having a gain/frequency characteristic such that the gain increases with frequency from a preset frequency to a frequency defining a maximum detection distance, has a substantially constant gain from a frequency defining a minimum detection distance to the preset frequency, and wherein the gain decreases below the frequency defining the minimum detection distance.
The radar of claim 12, wherein the preset frequency is a frequency below which the mixer circuit coupled to an input of said amplifier circuit begins to saturate.
A radar for detecting the distance to a target based on the frequency difference between a transmission signal and a reception signal, said radar comprising:
- a transmission circuit for generating a frequency-modulated transmission signal whose frequency varies in time;
- a mixer circuit for generating an IF signal representing the frequency difference between the reception signal and the transmission signal;
- an amplifier circuit for amplifying the IF signal;
- a DC blocking circuit provided at an input of said amplifier circuit;
- and
- an offset circuit for adding a predetermined DC offset, provided at the output of said amplifier circuit,
- said amplifier circuit having a gain/frequency characteristic such that the gain increases with frequency from a preset frequency to a frequency defining a maximum detection distance, has a substantially constant gain from a frequency defining a minimum detection distance to the preset frequency, and wherein the gain decreases below the frequency defining the minimum detection distance.
A radar for detecting the distance to a target based on the frequency difference between a transmission signal and a reception signal, said radar comprising:
- a transmission circuit for generating a frequency-modulated transmission signal whose frequency varies in time;
- a mixer circuit for generating an IF signal representing the frequency difference between the reception signal and the transmission signal;
- an amplifier circuit for amplifying the IF signal, the gain thereof having its peak at or below one half of a predetermined sampling frequency of an AD converter coupled to an output of the amplifier circuit;
- the AD converter sampling the IF signal at the predetermined sampling frequency and converting the IF signal from an analog signal to a digital signal;
- a first DC blocking circuit provided at an input of said amplifier circuit;
- a second DC blocking circuit provided at the output of said amplifier circuit;
- and
- an offset circuit, provided at the output of said amplifier circuit, for adding a predetermined DC offset to a signal from which DC component has been removed by said second DC blocking circuit,
- said amplifier circuit having a gain/frequency characteristic such that the gain increases with frequency from a preset frequency to a frequency defining a maximum detection distance, has a substantially constant gain from a frequency defining a minimum detection distance to the preset frequency, and wherein the gain decreases below the frequency defining the minimum detection distance.
Dependencies are inferred from the claim text.