Method and apparatus for attenuating a transmitted feedthrough signal
First Claim
Patent Images
1. A radar system to attenuate feedthrough, comprising:
- a first combiner to downconvert a received signal to a first intermediate frequency having a fixed frequency;
a second combiner to combine the first intermediate frequency and a second signal, the second signal comprising a fixed frequency component and an offset component, the offset component corresponding to a difference in frequency between a signal transmitted at a given point in time and a signal received as target return at the given point in time; and
a filter having a fixed stopband to receive an output of the second combiner for attenuating the downconverted signal transmitted at the given point in time and passing the downconverted target return signal received at the given point in time.
1 Assignment
0 Petitions
Accused Products
Abstract
A radar system includes a receiver that is capable of attenuating transmitter feedthrough in a receive signal. In some embodiments, a fixed frequency notch filter is used to attenuate feedthrough at an intermediate frequency (IF). In other embodiments, an electronically tunable notch filter is used. Phase compensation may be provided to correct for a phase shift of the notch filter.
57 Citations
36 Claims
-
1. A radar system to attenuate feedthrough, comprising:
-
a first combiner to downconvert a received signal to a first intermediate frequency having a fixed frequency; a second combiner to combine the first intermediate frequency and a second signal, the second signal comprising a fixed frequency component and an offset component, the offset component corresponding to a difference in frequency between a signal transmitted at a given point in time and a signal received as target return at the given point in time; and a filter having a fixed stopband to receive an output of the second combiner for attenuating the downconverted signal transmitted at the given point in time and passing the downconverted target return signal received at the given point in time. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A method, comprising:
-
downconverting, using a first combiner, a received signal to a first intermediate frequency having a fixed frequency; combining, using a second combiner, the first intermediate frequency and a second signal, the second signal comprising a fixed frequency component and an offset component, the offset component corresponding to a difference in frequency between a signal transmitted at a given point in time and a signal received as target return at the given point in time; and filtering an output of the second combiner with a filter having a stopband for attenuating the downconverted signal transmitted at the given point in time and passing the downconverted target return signal received at the given point in time. - View Dependent Claims (9, 10, 11, 12, 13)
-
-
14. A satellite tracking radar system, comprising:
-
a global positioning satellite (GPS) disciplined signal source; a first mixer to receive signal return from an antenna array, to receive a first local oscillator signal derived from the GPS disciplined signal source, and to output a first intermediate frequency at a fixed frequency; a second mixer to receive the first intermediate frequency, to receive a second local oscillator signal, and to output a second intermediate frequency signal, wherein the second local oscillator signal includes a fixed frequency component and an offset component, which corresponds to a difference in frequency between a signal transmitted at a given point in time and a signal received as target return at the given point in time; and a filter having a fixed stopband to receive the second intermediate frequency signal and attenuate the downconverted signal transmitted at the given point in time and pass the downconverted target return signal received at the given point in time. - View Dependent Claims (15, 16, 17, 18, 19)
-
-
20. A radio frequency (RF) receiver system for use in a radar system, comprising:
-
a receive antenna to receive a signal from a surrounding environment, the received signal having a transmitter feedthrough component and a return signal component, wherein the transmitter feedthrough component and the return signal component are at different frequencies; a first mixer to downconvert the received signal using a variable frequency local oscillator (LO) signal to generate a first IF signal having a transmitter feedthrough component at one frequency and a return signal component at another frequency, both in a first IF bandwidth; a notch filter having a fixed stop band; a second mixer to downconvert the first IF signal using a fixed frequency LO signal to generate a second IF signal having a transmitter feedthrough component at a frequency corresponding to the stop band of the notch filter and a return signal component at a frequency outside the stop band of the notch filter, wherein the notch filter is operative to filter the second IF signal to generate a filtered signal, wherein the notch filter attenuates the transmitter feedthrough component of the second IF signal and substantially passes the return signal component of the second IF signal. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
-
-
28. A method of operating a radio frequency (RF) receiver in a radar system, comprising:
-
receiving a signal having a transmitter feedthrough component and a return signal component, wherein the transmitter feedthrough component and the return signal component of the received signal are at different frequencies; downconverting the received signal using a variable frequency local oscillator (LO) signal to generate a first intermediate frequency (IF) signal having a transmitter feedthrough component at one frequency and a return signal component at another frequency, both in a first IF bandwidth; downconverting the first IF signal using a fixed frequency LO signal to generate a second IF signal having a transmitter feedthrough component at a frequency within a stop band of a fixed-band notch filter and a return signal component at a frequency outside the stop band of a fixed-band notch filter; and applying the second IF signal to the fixed-band notch filter to generate a filtered signal having an attenuated transmitter feedthrough component. - View Dependent Claims (29, 30, 31, 32, 33)
-
-
34. A radio frequency (RF) receiver system for use in a radar system, comprising:
-
a receive antenna to receive a signal from a surrounding environment, the received signal having a transmitter feedthrough component and a return signal component, wherein the transmitter feedthrough component and the return signal component are at different frequencies; a first mixer to downconvert the received signal using a variable-frequency local oscillator (LO) signal to generate a first IF signal having a transmitter feedthrough component and a return signal component; and an electronically tunable notch filter having an adjustable stop band frequency to filter the first IF signal to generate a filtered signal, wherein the electronically tunable notch filter is controlled to place the stop band at a frequency of the transmitter feedthrough component of the first IF signal. - View Dependent Claims (35, 36)
-
Specification