Narrow band spectrum analysis method and apparatus
US5691924A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 28, 1995 |
| Grant date | Nov 25, 1997 |
| Priority date | — |
| Expiry date | Jul 28, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01H1/14
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A zoom processor for increasing the resolution of a band of interest within an acquired analog time domain frequency signal. The signal is converted from an analog time domain signal to a digital time domain signal. Next, the signal is multiplied by a value which will lower the center frequency of the band of interest to zero. The value by which the signal is multiplied is based on both the sine and cosine of a function of the center frequency and the sampling frequency used to digitize the signal. The sine function is solved with the aid of a numerical substitution which simplifies finding the value of the function in a sine table. After the signal is shifted, it is low-pass filtered, which removes all of the signal except the band of interest. During filtering, the band is also decimated by a predetermined factor, which compresses the time domain signal, and proportionally expands the frequency domain signal which is produced at a later step of the method. A transform, such as a Fast Fourier Transform, is performed on the band, to convert the signal from time domain to frequency domain. The signal is analyzed according to the ultimate function of the instrument in which the zoom …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.