Digital communication system of orthogonal modulation type
US6512798B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 5, 1999 |
| Grant date | Jan 28, 2003 |
| Priority date | — |
| Expiry date | Mar 5, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/03834
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A digital signal communication system includes a transmission circuit or a receiving circuit for digitally transmitting two types of signals by orthogonal modulation. The transmission circuit includes an orthogonal modulator and a nonrecursive digital low-pass filter having the same frequency characteristic as a predetermined frequency characteristic of the output signal of the orthogonal modulator. The receiving circuit includes an orthogonal demodulator and a nonrecursive digital low-pass filter having the same frequency characteristic as a predetermined frequency characteristic of the output signal of the orthogonal demodulator. The total number of taps required for determining the frequency characteristic of the nonrecursive digital low-pass filter is set to H, and the series of tap coefficients is set as C1, C2, C3, . . . , CH, where H is an arbitrary positive integer of not less than 2. The nonrecursive digital low-pass filters include a first low-pass filter for filtering one of the two types of signal and a second low-pass filter for filtering the other type of the signal. The first low-pass filter has taps about one half of H including a tap coefficient series C1, C3, C5, …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.