Method and device for measuring the slope of the envelope delay characteristic of a transmission channel and their application to an automatic equalizer selection technique
US4245320A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 11, 1978 |
| Grant date | Jan 13, 1981 |
| Priority date | — |
| Expiry date | Oct 11, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B3/462
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method and device for measuring the slope of the envelope delay characteristic in a transmission channel. The slope is determined from a received measurement signal having a frequency spectrum that includes three rays at frequencies f.sub.o, f.sub.1 and f.sub.2, which are approximately located in the center and at the edges of the useful passband of the channel. At the output of the channel, the three components at frequencies f.sub.o, f.sub.1 and f.sub.2 are extracted from the received measurement signal, and the instantaneous phases .psi.0, .psi.1 and .psi.2 of these three components are measured. The value of the slope S of the envelope delay characteristic is obtained from the relation ##EQU1## where .phi..sub.o ', .phi..sub.1 ' and .phi..sub.2 ' are the phases of the three rays at frequencies f.sub.o, f.sub.1 and f.sub.2 of the measurement signal sent over the channel. When the data transmission system employs double sideband-quadrature carrier (DSB-QC) modulation, the measurement signal is generated by causing the carrier to undergo successive phase changes of +.pi./2 and -.pi./2 radians at the signaling rate. The receiver includes a set of fixed equalizers and the appropri…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.