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:
Apr. 09, 2002
Filed:
Mar. 31, 1999
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A modem ( ) including receive circuitry ( ) implemented by way of a digital signal processor ( ) is disclosed. The receive circuitry ( ) operates according to a receive clock (CLK ) that is based upon the output of a free run oscillator ( ). An incoming frequency multiplexed signal (f(t)) is sampled by an analog-to-digital converter ( ) and demodulated by way of a Fast Fourier Transform function ( ). After such demodulation, a phase rotation function ( ) applies a phase shift to the demodulated signal corresponding to an estimated phase offset (&tgr;) between the receive clock (CLK ) and a pilot signal (P) transmitted by the transmitting modem; a finite impulse response filter function ( ) applies a digital filter to the demodulated signal to correct for phase error based upon an estimated frequency offset (&Dgr;). According to another disclosed embodiment, a pre-emphasis FIR filter function ( ) and a pre-emphasis phase rotation function ( ) are applied to an upstream singal, based upon the estimated phase offset (&eegr;) and frequency offset (&Dgr;).