US4937775A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for the cross-correlation of a pair of complex sampled signals
Assignee: General Electric Co
•
Filing: 1988-11-21
•
Granted: 1990-06-26
•
Expires: 2008-11-21
Abstract
Abstract Apparatus for the cross-correlation of two complex sampled digital data signals X and Y uses a first N-stage CORDIC rotator of pipeline sequential form for rotating each of the real and imaginary data portions of the first (X) complex sampled signal sequentially through a summation of angles θ=ξ i α i where ξ i =+1 or -1, α 1 =90° and α n-2 =tan -1 (2 -n ) for n=0, 1, 2, 3, . . . N-2) until X Im is approximately zero and a substantially zero phase angle is reached. The sign from each i-th stage, of this first pipeline is also utilized to determine the sign of rotation in each like-positioned i-th stage of a plurality M of additional CORDIC pipeline rotators, where M is the total number of time delays at which the cross-correlation function is evaluated. The real and imaginary portions of the complete M-th interval cross-correlation product are each obtained by multiplying the associated complex output of each of the Y pipeline rotators by the first pipeline magnitude signal output; N samples are then summed to provide at the j-th rotator output the appropriate pair of the real and imaginary parts of the j-th complex digital data output sample C(j).
Inventors
- 👤 William E. Engeler
- 👤 Matthew N O'Donnell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 05:19
CPC Classifications
G; G06; G06F; G06F17/00; G06F17/10; G06F17/15
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
218 words
Apparatus for cross-correlating first and second complex digital data signals, comprising: a multiplier section having a first pipeline CORDIC rotator means with a plurality N of sequential stages, receiving separate and independent imaginary and real portions of the first complex data signal, for rotating the independent imaginary and real portions through predetermined decreasing angles α to progressively reduce the magnitude of the imaginary-portion of the first complex data signal toward zero in each of the plurality N of sequential stages, and providing output data equal to the absolute value of the first complex data signal; and a multiplicand section having a plurality M of additional pipeline CORDIC rotator means, each means having a like plurality N of sequential stages, for modifying the read and imaginary portions of the second complex data signal to cause rotation, responsive to a selection signal, through each of like angles α and with a rotation in each j-th rotator means, where 1≦j≦(M-1), being progressively delayed by one common delay time interval greater than a total time delay in the previous (j-1)-th rotator means; and means for arithmetically processing the modified second complex data signal from all of the M additional rotator means to provide, at any one time one set of data corresponding to the cross-correlation of both complex signals at that time.
Claim 2
Dependent Claim
218 words
Apparatus for cross-correlating first and second complex digital data signals, comprising: a multiplier section having a first pipeline CORDIC rotator means with a plurality N of sequential stages, receiving separate and independent imaginary and real portions of the first complex data signal, for rotating the independent imaginary and real portions through predetermined decreasing angles α to progressively reduce the magnitude of the imaginary-portion of the first complex data signal toward zero in each of the plurality N of sequential stages, and providing output data equal to the absolute value of the first complex data signal; and a multiplicand section having a plurality M of additional pipeline CORDIC rotator means, each means having a like plurality N of sequential stages, for modifying the read and imaginary portions of the second complex data signal to cause rotation, responsive to a selection signal, through each of like angles α and with a rotation in each j-th rotator means, where 1≦j≦(M-1), being progressively delayed by one common delay time interval greater than a total time delay in the previous (j-1)-th rotator means; and means for arithmetically processing the modified second complex data signal from all of the M additional rotator means to provide, at any one time one set of data corresponding to the cross-correlation of both complex signals at that time.
Claim 3
Dependent Claim
75 words
The apparatus of claim 1, wherein each of the plurality N of stages in the first rotator means rotates each real and imaginary input data portion in a direction selected by a selection data bit state dependent upon a sign of the imaginary-portion data input to that stage; and each stage includes one of a plurality N of comparator means for monitoring the stage imaginary-portion data input to establish the said selection data bit state.
Claim 4
Dependent Claim
28 words
The apparatus of claim 2, wherein the comparator means connected to each stage of the first rotator means receives the imaginary-portion data output from an immediately previous stage.
Claim 5
Dependent Claim
38 words
The apparatus of claim 1, wherein angle α i is the rotational angle for the i-th stage, where 1≦i≦N, with α 1 =90° and α i =tan -1 (2 -n )° with n=i-31 2 i=2,3,. . . ,N.
Claim 6
Dependent Claim
124 words
The apparatus of claim 1, wherein said multiplicand section further includes: a plurality (M-1)xN of means for delaying an input data signal by one common-time-interval (CTI), each delay means receiving the selection signal from a selected i-th stage, where 1≦i≦N, of a previous j-th one of the additional rotator means and providing a delayed selection signal to the same i-th stage of a next (j+1)-th one of the additional rotator means; and a plurality 2M of final means, each coupled to one of the real-portion and imaginary-portion outputs of each of the M additional rotator means, for processing that rotator means output with the first complex data signal absolute value to obtain a like portion of that one of M time-delayed correlator data outputs.
Claim 7
Dependent Claim
104 words
The apparatus of claim 5, wherein each of said plurality of final means includes: means for obtaining data equal to a product of the associated multiplicand section output data and the multiplier section absolute value output data; means for delaying the product data by N common-time-intervals (CTIs); first adder means for subtracting the delayed product data from the product data to provide a first added output; second adder means for adding the first added output and a correlator data output for that portion, to provide a second added output; and means for accumulating the second added output to provide the portion correlator data output.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-25 | 1993-12-25 | 1994-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-25 | 1997-12-25 | 1998-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-25 | 2001-12-25 | 2002-06-26 | $7700.00 | Window Closed / Lapsed |