The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 22, 2008
Filed:
Jun. 03, 2004
Andrew Alfred Moulthrop, Los Angeles, CA (US);
Michael Steven Muha, Torrance, CA (US);
Christopher Patrick Silva, Rancho Palos Verdes, CA (US);
Andrew Alfred Moulthrop, Los Angeles, CA (US);
Michael Steven Muha, Torrance, CA (US);
Christopher Patrick Silva, Rancho Palos Verdes, CA (US);
The Aerospace Corporation, El Segundo, CA (US);
Abstract
A communications system reduces downconverter inaccuracies in time-domain measurements or samples of received microwave communications I and Q complex signals by converting received signal to baseband taking measurements or samples of the I and Q waveforms at differing phase shifts of a demodulating carrier signal for a local oscillator or carrier tracking loop used during downconversion so that I and Q imbalances may be detected and removed by lowpass equivalent averaging for improved characterization of downconverters or for improved signal reception. In the preferred form, the phase shifts are 0 and π/2 for a conventional measurement, and then at θ, and θ+π/2, with θ=π/4+mπ/2 for an integer m for the second measurement where I and Q imbalances and baseband nonlinearities are indicated by differences between the two measured or sampled signals, where θ provides for optimum error detection for reducing the errors by averaging the measurements.