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US 2010/0135439 A1Published application
Integrated interference cancellation system architecture with distortion connection
AssigneeBAE Systems Information and Electronic Systems Integration Inc.
InventorRaymond J. Lackey
Life of this patent
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Abstract
A system and associated method is provided for improved rejection of an interfering signal coupled from a transmission antenna into a local receive antenna in the presence of local multipath. A system of the invention includes a common feedback junction, (i.e., a single sampling point used by all parameter matching control loops), for adjusting a number of distortion matching circuits while advantageously maintaining independence of tuning and other independent circuit actions.
Claims29
A method and apparatus for reducing the effects of interference between collocated transceivers, the method comprising:
- a) matching a time delay of a first received signal in a controlled propagation path to a second received signal over an uncontrolled propagation path;
- b) continuously and automatically frequency tuning a lobed amplitude slope matching filter (ASMF) applied to the first received signal to allow tracking of the first received signal to match a dynamically changing amplitude slope of the second received signal;
- c) continuously and automatically tuning a quadratic amplitude matching filter (QAMF) applied to the first received signal to allow tracking of the first received signal to match a dynamically changing quadratic amplitude distortion of the second received signal;
- d) acquiring a first error measurement signal responsive to an adaptive control loop for adjusting a complex weighting of the delayed coupled first received signal with current match to maximally cancel the propagated second received signal;
- e) acquiring a second error measurement signal responsive to said step (a) of matching a time delay of the first received signal in a controlled propagation path to the second received signal over an uncontrolled propagation path;
- f) acquiring a third error measurement signal responsive to said step (b) of continuously and automatically tuning a lobed amplitude slope matching filter (ASMF) applied to the first received signal to allow tracking of the first received signal to match a dynamically changing amplitude slope of the second received signal;
- g) acquiring a fourth error measurement signal responsive to said step (c) of continuously and automatically tuning a quadratic amplitude matching filter (QAMF) applied to the first received signal to match a dynamically changing quadratic amplitude slope distortion of the second received signal;
- and
- h) repeating steps a-g until the first, second, third and fourth error measurement signals are minimized.
6 more elements
A method and apparatus for reducing the effects of interference between collocated transceivers, the method comprising:
- a) matching a time delay of a first received signal in a controlled propagation path to a second received signal over an uncontrolled propagation path;
- b) continuously and automatically frequency tuning a lobed amplitude slope matching filter (ASMF) to the first received signal to allow tracking of the first received signal to match a dynamically changing amplitude slope of the second received signal using an offline process;
- c) continuously and automatically tuning a quadratic amplitude matching filter (QAMF) to the first received signal, to allow tracking of the first received signal to match a dynamically changing quadratic amplitude distortion of the second received signal;
- d) acquiring a first error measurement signal responsive to an adaptive control loop for adjusting a complex weighting of the delayed coupled signal with current match to maximally cancel the propagated received signal;
- e) acquiring a second error measurement signal responsive to said step (a) of matching a time delay of the first received signal in a controlled propagation path to the second received signal over an uncontrolled propagation path;
- f) acquiring a third error measurement signal responsive to said step (b) of continuously and automatically tuning a lobed amplitude slope matching filter (ASMF) to the first received signal to allow tracking of the second received signal to match a dynamically changing amplitude slope of the inserted signal;
- g) acquiring a fourth error measurement signal responsive to said step (c) of continuously and automatically tuning a quadratic amplitude matching filter (QAMF) to the first received signal to match a dynamically changing quadratic amplitude slope distortion of the second received signal;
- and
- h) repeating steps (a-g) until the first, second, third and fourth error measurement signals are minimized.
6 more elements
An interference cancellation system, comprising:
- (A) a variable delay line (19) for adjusting a signal propagation time of a sampled transmission signal (40), the variable delay line (19) comprising:
- (i) a single or multiple fixed delay elements (80, 82) in series with the propagated received signal path;
- (ii) a variable delay element (11) for continuously varying a delay of sampled transmission signal (40) to implement a match between a sampled transmission signal (40) and a propagated received signal (30) yielding a delayed coupled signal (57);
- (B) an adaptive time delay control (ATDC) module (10) for calculating a delay to be added to a first propagation path to achieve a match of the first signal passing through a controlled propagation path with a second signal passing through an uncontrolled propagation path;
- and
- (C) an adaptively tuned sloped control (ATSC) module (200) for providing a tuning procedure directed to an ASMF control function to the band of interference and for externally controlling the ASMF control function subsequent to said tuning, said adaptively tuned sloped control (ATSC) module 200 comprising:
- (i) an inline variable lobe filter structure (VLFS) (201) for providing controlled variable time delay for generating a broadband RF tuning filter formed by a delay T and a slope control filter lobe formed by a first delay and a second delay (2nT) (208) yield a total time delay of (2n+1)T centered in the null of the tuning filter and skewed by an external slope control signal;
- (ii) an offline time delay tuning control (TDTC) element (202) for receiving signal samples output from the inline variable lobe filter structure (VLFS) 201 to control a first variable time delay element (T) 205 of the inline variable lobe filter structure (VLFS) 201 to provide said controlled variable time delay to generate said broadband RF tuning filter and a second variable time delay element (2nT) 208 of the inline variable lobe filter structure (VLFS) 201 to provide said controlled variable time delay to generate said slope control filter lobe;
- and
- (D) an adaptively tuned quadratic control (ATQC) module (200) for providing a tuning procedure directed to a quadratic amplitude matching filter (QAMF) (100) control function to the band of interference and for externally controlling the QAMF control function subsequent to said tuning, said adaptively tuned quadratic control (ATQC) module (200) comprising:
- (i) an inline variable lobe filter structure (VLFS) (201) for providing controlled variable time delay for generating a broadband RF tuning filter formed by a delay T and a first narrowband inline control filter for providing a near-flat quadratic control filter lobe formed by a first delay (T) and a second delay (2nT) yielding a total time delay of (2n+1)T centered in the null of the broadband RF tuning filter and weighted by an external amplitude control signal;
- (ii) a second narrowband inline control filter as a slaved lobe filter structure-down (104) for providing a down quadratic amplitude control filter lobe formed by a delay of (2m+1)T centered in the null of the RF tuning filter and weighted by an external amplitude control signal;
- (iii) a third narrowband inline control filter as a slaved lobe filter structure-up (105) for providing a up quadratic amplitude control filter lobe formed by a simple FIR filter with inter-tap spacing delay of (2o+1)T centered in the null of the tuning filter and weighted by an external amplitude control signal;
- (E) an adaptive control loop (6) for adjusting a complex weighting of the delayed coupled signal (57) to maximally cancel the propagated received signal (30).
11 more elements
The interference cancellation system of claim 50, wherein other circuits with variable distortions of time delay, amplitude slope, and quadratic amplitude shapes can be included within the processing chain and their errors will be corrected by the adaptive processes of these circuits.
An interference cancellation system, comprising:
- (A) a variable delay line (19) for adjusting a signal propagation time of a sampled transmission signal (40), the variable delay line (19) comprising:
- (i) a single or multiple fixed delay elements (80, 82) in series with the propagated received signal path;
- (ii) a variable delay element (11) for continuously varying a delay of sampled transmission signal (40) to implement a match between a sampled transmission signal (40) and a propagated received signal (30) yielding a delayed coupled signal (57);
- (B) an adaptive time delay control (ATDC) module (10) for calculating a delay to be added to a first propagation path to achieve a match of the first signal passing through a controlled propagation path with a second signal passing through an uncontrolled propagation path;
- and
- (C) an adaptively tuned sloped control (ATSC) module 200 for providing a tuning procedure directed to an ASMF control function to the band of interference and for externally controlling the ASMF control function subsequent to said tuning, said adaptively tuned sloped control (ATSC) module (200) comprising:
- (i) an inline variable lobe filter structure (VLFS) 201 for providing controlled variable time delay for generating;
- (1) a first broadband RF lobed filter formed by a delay T−ΔT, a second broadband RF lobed filter formed by a delay T+ΔT, and (3) a slope control filter lobe formed by a first delay T (205) and a second delay (2nT) (208) yield a total time delay of (2n+1)T centered in the null of the imaginary broadband RF lobed nulling filter and skewed by an external slope control signal;
- (ii) an offline time delay tuning control (TDTC) element (202) for receiving signal samples output from the inline variable lobe filter structure (VLFS) (201) to control in a consistent trend a first variable time delay element (T) (205) of the inline variable lobe filter structure (VLFS) 201 to provide said controlled variable time delay to generate said broadband RF tuning filter and a second variable time delay element (2nT) (208) of the inline variable lobe filter structure (VLFS) 201 to provide said controlled variable time delay to generate said slope control filter lobe.
- (D) an adaptively tuned quadratic control (ATQC) module (200) for providing a tuning procedure directed to a quadratic amplitude matching filter (QAMF) (100) control function to the band of interference and for externally controlling the QAMF control function subsequent to said tuning, said adaptively tuned quadratic control (ATQC) module (200) comprising:
- (i) an inline variable lobe filter structure (VLFS) (201) for providing controlled variable time delay for generating a broadband RF tuning filter formed by a delay T and a first narrowband inline control filter for providing a near-flat quadratic control filter lobe formed by a first delay (T) and a second delay (2nT) yielding a total time delay of (2n+1)T centered in the null of the broadband RF tuning filter and weighted by an external amplitude control signal;
- (ii) a second narrowband inline control filter as a slaved lobe filter structure-down (104) for providing a down quadratic amplitude control filter lobe formed by a delay of (2m+1)T centered in the null of the RF tuning filter and weighted by an external amplitude control signal;
- (iii) a third narrowband inline control filter as a slaved lobe filter structure-up (105) for providing a up quadratic amplitude control filter lobe formed by a simple FIR filter with inter-tap spacing delay of (2o+1)T centered in the null of the tuning filter and weighted by an external amplitude control signal;
- (E) an adaptive control loop (6) for adjusting a complex weighting of the delayed coupled signal (57) to maximally cancel the propagated received signal (30).
11 more elements
Dependencies are inferred from the claim text.