Browse Prior Art Database

Biphase DPSK Detection

IP.com Disclosure Number: IPCOM000089114D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bigo, F: AUTHOR [+2]

Abstract

The proposed biphase DPSK (differential phase shift keyed) detection process takes advantage of scalar product properties for providing a new, fully digital detector.

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Biphase DPSK Detection

The proposed biphase DPSK (differential phase shift keyed) detection process takes advantage of scalar product properties for providing a new, fully digital detector.

In biphase DPSK modulation each bit to be transmitted is encoded as a carrier phase change relative to the phase of the immediately preceding bit. The phase changes are typically 0 degrees and 180 degrees for bits 0 and 1, respectively. At the receiver, the carrier phase changes are detected, and the data bits are derived therefrom. The concept of rotating vector can be used to represent the DPSK received signal at modulation instants.

In the vector diagram shown in the figure, vector R(n-1) represents the signal received at modulation instant (n-1)T, T being the modulation period. Its magnitude 1(n-1) and phase phi(n-1) represent the magnitude and phase of the received signal. Vector R(n-1) can be defined by the inphase and quadrature components X(n-1) and Y(n-1), respectively, of the received signal. Should the transmission channel be ideal, vector R(n) representative of the signal received at instant nT will be either a vector coincident with R(n-1) (phase change equal to 0 degrees) or a vector whose phase is 180 degrees out of phase relative to R(n- 1).

In actual transmission systems, due to transmission impairments, if the signal transmitted at instant nT exhibits a 0 degrees phase change relative to R(n-1), it will be received as vector R/1/(n) with phase change theta(1)...