Self-adaptive digital filter for noise and phase jitter reduction
US4106102A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 15, 1976 |
| Grant date | Aug 8, 1978 |
| Priority date | — |
| Expiry date | Nov 15, 1996 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2027/0065
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A new adaptive digital tuning filter for tracking a sinusoidal signal within a frequency band is described. The input signal representative of both said sinusoidal signal and noise is fed to a Hilbert transformer which provides the in-phase and quadrature components, x.sub.k and x.sub.k, respectively, of said sinusoidal signal. These components are applied to the input of a filter having a transfer function K where ##EQU1## WHERE .phi. = 2.pi.FT, f is the tuned frequency of the filter, PA1 T is the signal sampling period and a is a constant close to unity. The output signals y.sub.x and y.sub.x of the filter are applied to a computing means which provides a frequency control signal e.sub.k such that EQU e.sub.k = x.sub.k y.sub.k - y.sub.k x.sub.k The above value of .phi. is adjusted through a conventional gradient method where EQU .phi..sub.k + 1 = .phi..sub.k + .mu.e.sub.k and controls are provided to adjust .phi. in a direction to change e.sub.k toward zero. Application of the adaptive tuning filter to cancellation of the main component of phase jitter in a modem is also described.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.