Gated range scanning LFMCW radar structure
The present disclosure provides a gated range scanning linear frequency modulated continuous wave (LFMCW) radar structure, including: a frequency synthesizer, a first mixer, a second mixer, a first filter, and a third mixer. The frequency synthesizer is configured for generating a first local oscillating signal and a second local oscillating signal, a frequency of the first local oscillating signal varying in a frequency range, each frequency corresponding to a sub-range of a coverage range scanned by the LFMCW radar structure. The first mixer is configured for mixing a copy of a transmitted signal and the first local oscillating signal to generate a first output signal (the receiver's first local oscillator). The second mixer is configured for mixing the first output signal and a received signal from a receiving antenna to generate a second output signal that includes an intermediate frequency (IF) signal being received by the first filter.
1. A gated range scanning linear frequency modulated continuous wave (LFMCW) radar structure, comprising:
a frequency synthesizer, a first mixer, a second mixer, a first filter, and a third mixer, wherein:
the frequency synthesizer is configured for generating a first local oscillating signal and a second local oscillating signal, a frequency of the first local oscillator signal varying in a frequency range, each frequency corresponding to a sub-range of a coverage range scanned by the LFMCW radar structure;
the first mixer is configured for mixing a copy of a transmitted radar signal and the first local oscillating signal to generate a first output signal, corresponding to receiver's first local oscillating signal;
the second mixer is configured for mixing the first output signal and a received signal from a receiving antenna to generate a second output signal that includes an intermediate frequency (IF) signal being received by the first filter;
the first filter is configured for generating a third output signal by filtering the second output signal and selecting a first frequency component to form the IF signal, a frequency of the IF signal corresponding to a sub-range of the coverage range scanned by the LFMCW radar structure; and the third mixer is configured for mixing the second local oscillating signal and the third output signal to generate a fourth output signal that includes a baseband signal.
2. The gated range scanning LFMCW radar structure further comprising a second filter, configured for filtering out high frequency components from the fourth output signal and obtaining the baseband signal.
3. The gated range scanning LFMCW radar structure according to claim 2 , wherein the frequency synthesizer, the first mixer, the second mixer, the third mixer, the first filter, and the second filter form a double superheterodyne receiver structure.
4. The gated range scanning LFMCW radar structure according to claim 1 , wherein the first filter is a band-pass filter having a narrow passband and a steep skirt.
5. The gated range scanning LFMCW radar structure according to claim 4 , wherein the first frequency component of the second output signal falls between a lowest frequency of the pass band and a highest frequency of the pass band of the first filter, and other frequency components of the second output signal fall out of the pass band of the first filter.
6. The gated range scanning LFMCW radar structure according to claim 1 , wherein the frequency of the first local oscillating signal is of high stability.
7. The gated range scanning LFMCW radar structure according to claim 1 , wherein a frequency component outputted by the first mixer corresponds to a sub-range of the coverage range scanned by the LFMCW radar structure; a lowest frequency component corresponds to a farthest sub-range, and a highest frequency component corresponds to a closest sub-range.
8. The gated range scanning LFMCW radar structure according to claim 2 , further comprising:
a transmitter, a radar data processor and controller, and a receiver, the receiver comprising the frequency synthesizer, the first mixer, the second mixer, the first filter, the second filter, and the third mixer.
9. A method of range scanning, using a gated range scanning linear frequency modulated continuous wave (LFMCW) radar structure, the gated range scanning LFMCW radar structure comprising a frequency synthesizer, a first mixer, a second mixer, a first filter, and a third mixer, the method comprising:
generating a first local oscillating signal and a second local oscillating signal, a frequency of the first local oscillating signal varying in a frequency range, each frequency corresponding to a sub-range of a coverage range scanned by the LFMCW radar structure;
mixing a copy of a transmitted radar signal and the first local oscillating signal to generate a first output signal;
mixing the first output signal and an amplified received signal from a receiving antenna to generate a second output signal having an intermediate frequency (IF) signal;
generating a third output signal by filtering the second output signal and selecting a first frequency component to form the IF signal, a frequency of the IF signal corresponding to a sub-range of the coverage range scanned by the LFMCW radar structure; and
mixing the second local oscillating signal and the third output signal to generate a fourth output signal, which includes a baseband signal.
10. The method according to claim 8 , further comprising: filtering out high frequency components from the fourth output signal and obtaining the baseband signal through a second filter.
11. The method according to claim 10 , wherein the frequency synthesizer, the first mixer, the second mixer, the third mixer, the first filter, and the second filter form a double superheterodyne receiver structure.
12. The method according to claim 10 , wherein the first filter is a band-pass filter having a narrow passband and a steep skirt.
13. The method according to claim 12 , wherein the frequency of the IF signal falls in the pass band of the first filter, and other frequency components of the second output signal falls out of the pass band of the first filter.
14. The method according to claim 10 , wherein the frequency of the first local oscillating signal is of high stability.
15. The method according to claim 10 , wherein a lowest frequency outputted by the first mixer corresponds to a sub-range of the coverage range that is farthest to the LFMCW radar structure, and a highest frequency outputted by the first mixer corresponds to a sub-range of the coverage range that is closest to the LFMCW radar structure.
16. The method according to claim 10 , wherein the gated range scanning LFMCW radar further comprising: a transmitter, a radar data processor and controller, and a receiver, the receiver comprising the frequency synthesizer, the first mixer, the second mixer, the first filter, the second filter, and the third mixer.