Title :
Asynchronous timing recovery in DSP based PSK modems
Author :
Koblents, B. ; McLane, P.J.
Author_Institution :
Dept. of Electr. Eng., Queen´´s Univ., Kingston, Ont., Canada
Abstract :
Fully digital asynchronous timing recovery has been demonstrated to give excellent results in laboratory experiments on speech rate (2400 and 4800 b/s) modems with both rectangular and RC pulse shaping. F.M. Gardner´s (1986) zero crossing tracker timing error detector has been applied to rectangular and RC-pulse-shaped speech-rate modems with good results on the additive noise channel. The nondata-aided (NDA) form of the zero crossing tracker has been found to be immune to pattern noise for any data phase transition, making it ideal for timing error detection in M-PSK and M-DPSK systems with M>4. In RC-pulse-shaped systems with α down to 60%, intersymbol interference (ISI) induced self noise is sufficiently controlled by loop filtering. For systems with a limited number of samples per symbol, polyphase filter interpolation can be used to improve performance
Keywords :
digital signal processing chips; error detection; intersymbol interference; modems; phase shift keying; DSP based PSK modems; M-DPSK; M-PSK; RC pulse shaping; additive noise channel; data phase transition; digital asynchronous timing recovery; induced self noise; intersymbol interference; loop filtering; pattern noise; polyphase filter interpolation; rectangular pulse shaping nondata-aided zero crossing tracker; speech rate modems; timing error detection; zero crossing tracker timing error detector; Additive noise; Detectors; Digital signal processing; Intersymbol interference; Laboratories; Modems; Phase shift keying; Pulse shaping methods; Speech; Timing;
Conference_Titel :
Signals, Systems and Computers, 1992. 1992 Conference Record of The Twenty-Sixth Asilomar Conference on
Conference_Location :
Pacific Grove, CA
Print_ISBN :
0-8186-3160-0
DOI :
10.1109/ACSSC.1992.269195
