Boots – shoes – and leggings
Patent
1997-02-27
1998-06-30
Trammell, James P.
Boots, shoes, and leggings
455304, 375349, G01G 2500
Patent
active
057743754
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCJ/DE95/01125 filed Aug. 24, 1995.
The invention relates to a method and an apparatus for the correction of signalpairs, comprising inphase (I) and quadrature signals (Q) which are representable as vectors.
STATE OF THE ART
Analog or digital perpendicular signal-pairs in particular are applicated, where two signals are transferred at the same time by means of only one carrier-signal, for instance at the television with the modulation of the carrier for the color signal at the PAL-standard, or at the vector modulation, but also, where the signal spectra are converted into another frequency range, such as in radio signals, the processing of radar signals and the sonometrie. The method of the invention and the apparatus thereby advantageously can be utilized for the correction of angular modulated signals.
Due to non ideal components having a tolerance linear distortions of the base band signals arise, among other things through mismatch of the amplitudes and phases, the offset of the DC-signal and the frequency, as well as through non linear distortions caused by crosstalk and intermodulation.
Correction devices take remedial measures, which are detecting systematic and statistical errors of the perpendicular pair of signals by means of suitable detectors and generating correction signals thereof, in order to adjust the errors through feedback.
In EP 473 373 a system for calibrating a homodyne receivers is described, in order to adjust the error of the phase in the HF-front-end. The described system has the disadvantage, that the operation is interrupted in intervals for the injection of an auxiliary carrier and that the reference signal distinguishes from the received signal, so that only an approximated correction of the phase is taking place.
In EP 343 273 in a process following the HF-front-end, the whole linear distortions named above, with exception of the frequency offset, are detected and adjusted by multiple underlying feedback's. The disadvantage of this procedure is the concatenation of the control variables and the need of control permanently increased therewith, as well as the risk of instability associated therewith. This state of the art a separately and commutative, separate of each other feasible correction of the DC-offset, of the amplitude- and phase-error is to be gathered. The solution is based on a calculation of most probably values insofar, as DC-signal parts are determined for the calculation of values for correction.
In EP 595 278 the determination of the whole error values of I- and Q-signals at homodyne receivers by a calculation of most probably values is claimed, e.g. by a linear regression (see I. O. Kerner "Bester Kegelschnitt durch n Punkte" ZAMM 59, pp. 396-397, 1979). The disadvantage of the procedure is the complex calculational effort for the solution of a square matrix for five unknown parameters of an ellipsis, which is also not revealed in that patent specification.
From EP 598 277 and DE 39 38 643 a method and an apparatus for the offset correction is known. Thereby it is required that the correction of the ellipsis has taken place before.
For the correction of the offset of the center point the coordinates of the center point of two I- and Q-signals being in quadrature and displaced about the center point are determined by means of calculation of the most probably values such, that lines of centers of gravity are formed and a common intersection point will be determined. For this, a number of differences of square radii of respective two successive points are minimized and subtracted of the I- and Q-signals. The linearization and minimization of the function is also carried out according to I. O. Kerner. Such a solution is showing a comparatively great deviation of the actual centers because of the finite precision of calculating of the executive arithmetic units. In particular the rounding errors are greatly increasing with growing distortion.
In EP 595 277 the frequency-offset of the local oscillator at homodyne receivers is claimed
REFERENCES:
patent: 4475088 (1984-10-01), Beard
patent: 5165051 (1992-11-01), Kumar
patent: 5230099 (1993-07-01), Loper
patent: 5371481 (1994-12-01), Tittanen et al.
patent: 5590158 (1996-12-01), Yamaguchi et al.
I.O. Kerner, "Bester Kegelschnitt durch n Pinkte", ZAMM 59, pp. 396-397, 9.7
SICAN Gesellschaft fur Silizium-Anwendungen und CAD/CAT Niedersa
Trammell James P.
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