Digital multi-channel demultiplexer/multiplexer (MCD/M) architecture
US6091704A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 1, 1999 |
| Grant date | Jul 18, 2000 |
| Priority date | — |
| Expiry date | Feb 1, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04J1/05
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A digital signal processing system for multiplexing/demultiplexing a large number of closely spaced FDM channels in which sub-band definition filtering divides the FDM spectral band comprised of "N" channels into "K" sub-bands in order to reduce the dimension of the polyphase filter fast Fourier transform structure required to complete the multiplexing/demultiplexing. This reduces the order of the required prototype filter by a factor proportional to K. The number of sub-bands K is chosen so that it is large enough to ensure the polyphase filter, fast Fourier transform structure for each sub-band is realizable within a finite word length, fixed point arithmetic implementation compatible with a low power consumption. To facilitate efficient sub-band definition filtering, the real basebanded composite signal is inputted at a spectral offset from DC equal to one quarter the FDM channel bandwidth for the N channels and the signal is sampled at a frequency 50% greater than the applicable Nyquist rate. The quarter band spectral offset and oversampling by 50% above the theoretical Nyquist rate facilitate the use of computationally efficient bandshift and symmetric half-band Finite Impulse…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.