Timing acquisition in voiceband data sets
US4416015A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 30, 1981 |
| Grant date | Nov 15, 1983 |
| Priority date | — |
| Expiry date | Dec 30, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2007/047
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In a multipoint data communication system using quadrature-amplitude modulation, a master modem and a plurality of tributary modems are interconnected via respective transmission channels. Adaptive equalizer circuitry in the master modem equalizes the channel from a particular tributary by multiplying samples of signals received from the tributary by an ensemble of tap coefficients associated with the tributary. The tap coefficient ensembles for each tributary are stored in a memory from which they are retrieved at the start of transmission from that tributary. Timing acquisition circuitry within the master modem adjusts the phase of the latter's sampling circuitry at the start of transmission from a given tributary so that the received signals are sampled at the correct time points. In particular, a timing acquisition signal is transmitted by the tributary. The master samples and equalizes the received timing acquisition signal to form a succession of timing acquisition equalizer outputs. Each timing acquisition equalizer output is multiplied by its complex conjugate to form a timing acquisition envelope sample. The time by which the operation of the sampling circuitry is to be ad…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.