Method and apparatus for frequency analysis of telephone signals
US4932062A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 15, 1989 |
| Grant date | Jun 5, 1990 |
| Priority date | — |
| Expiry date | May 15, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L15/00
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
For faster realtime analysis related to Discrete Fourier Transform (DFT), prestored pre-multiplied values of amplitude times cosine and sine functions are used. Method and apparatus for determining the content of a predetermined frequency bin f in the frequency spectrum of a signal and, in particular, a signal which occurs in a telephone network, includes the step of storing on a storage means: EQU C.sub.k (x.sub.k,n)=x.sub.k *cos(2.pi.kn/N) and S.sub.k (x.sub.k,n)=x.sub.k *sin(2.pi.kn/N) for: k=0, . . . , (N-1); n=0, . . . , (n-1); and x.sub.k ranging over all the values of the set of M predetermined digital levels into which the amplitude of the signal is mapped, if the signal is a digital signal, or into which a sample of the amplitude of the signal is mapped, if the signal is an analog signal. N is a predetermined number of amplitudes or samples of the amplitude of the signal which are used in analyzing the frequency spectrum and n is a frequency index.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.