Double sideband linear frequency modulation system for radar applications
First Claim
1. In a radar system wherein a continuous wave of electromagnetic energy is transmitted toward an object and reflected energy is received from the object, the improvement of a double sideband linear frequency modulation system comprising:
- transmitting means providing upper and lower sidebands of a carrier signal with simultaneously increasing and decreasing transmitted frequency waveforms;
receiving means adapted for receiving reflected portions of said transmitted waveforms, and for separating said reflected portions into said upper and lower sidebands of said carrier signal, said upper and lower portions of reflected energy having both range and doppler signal components therein simultaneously; and
signal processing means for coherently combining the reflected sideband portions for separating the range and doppler signal components, said signal processing means comprising a first mixer having inputs adapted for receiving said reflected sideband portions for providing a sideband sum output, and a notch filter responsive to said sum output for eliminating clutter and thereby enhancing the frequency component of the signal output therefrom for determining radial velocity of the object.
1 Assignment
0 Petitions
Accused Products
Abstract
A double sideband linear frequency modulation technique for radar applications is disclosed for obtaining simultaneous range and doppler measurements. The method of obtaining measurements is useful in a variety of radar applications; however, the most promising area is in continuous wave radar systems. Linear Frequency Modulated (LFM) waveforms of both increasing and decreasing frequency are simultaneously transmitted. Upon reception, these sideband signals are combined coherently to give an output that is a function of the target'"'"'s radial velocity. The received signals are also processed separately to obtain target ranging information.
-
Citations
7 Claims
-
1. In a radar system wherein a continuous wave of electromagnetic energy is transmitted toward an object and reflected energy is received from the object, the improvement of a double sideband linear frequency modulation system comprising:
- transmitting means providing upper and lower sidebands of a carrier signal with simultaneously increasing and decreasing transmitted frequency waveforms;
receiving means adapted for receiving reflected portions of said transmitted waveforms, and for separating said reflected portions into said upper and lower sidebands of said carrier signal, said upper and lower portions of reflected energy having both range and doppler signal components therein simultaneously; and
signal processing means for coherently combining the reflected sideband portions for separating the range and doppler signal components, said signal processing means comprising a first mixer having inputs adapted for receiving said reflected sideband portions for providing a sideband sum output, and a notch filter responsive to said sum output for eliminating clutter and thereby enhancing the frequency component of the signal output therefrom for determining radial velocity of the object. - View Dependent Claims (2, 3, 4, 5)
- transmitting means providing upper and lower sidebands of a carrier signal with simultaneously increasing and decreasing transmitted frequency waveforms;
-
6. In a radar system wherein a continuous wave of high frequency electromagnetic energy is transmitted toward an object and reflected energy is received from the object, the method of simultaneously processing both object range and doppler signal components coincident in a reflected energy waveform and comprising the steps of:
-
mixing a carrier signal frequency with a linear frequency modulator output signal and filtering the resultant mixed output for obtaining respective upper and lower modulated sideband waveforms in separate channels; combining said sideband waveforms so that the upper sideband is increasing and the lower sideband is decreasing simultaneously at a linear frequency modulation rate; transmitting the combined waveforms toward an object; receiving portions of the combined waveforms reflected from an object; filtering the received waveforms into the respective upper and lower sidebands in separate channels; continuously mixing a reference signal portion of the transmitted upper and lower sidebands with respective upper and lower received sideband portions; passing the continuously mixed upper sideband signal portion and continuously mixed lower sideband signal portion through respective bandpass filters and band rejection filters for removing clutter and providing ranging signals; recombining portions of said continuously mixed lower sidebands and upper sidebands after passage of these signals through said bandpass filters and before passage through said band rejection filters for providing a summation signal output; and processing said summation signal through a bandpass filter and a notch filter to selectively obtain the frequency components comprising the in-phase and quadrature components for providing the object radial velocity. - View Dependent Claims (7)
-
Specification