NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Intersymbol Interference Investigations Using a 3D Time-Dependent Traveling Wave Tube ModelFor the first time, a time-dependent, physics-based computational model has been used to provide a direct description of the effects of the traveling wave tube amplifier (TWTA) on modulated digital signals. The TWT model comprehensively takes into account the effects of frequency dependent AM/AM and AM/PM conversion; gain and phase ripple; drive-induced oscillations; harmonic generation; intermodulation products; and backward waves. Thus, signal integrity can be investigated in the presence of these sources of potential distortion as a function of the physical geometry and operating characteristics of the high power amplifier and the operational digital signal. This method promises superior predictive fidelity compared to methods using TWT models based on swept- amplitude and/or swept-frequency data. First, the TWT model using the three dimensional (3D) electromagnetic code MAFIA is presented. Then, this comprehensive model is used to investigate approximations made in conventional TWT black-box models used in communication system level simulations. To quantitatively demonstrate the effects these approximations have on digital signal performance predictions, including intersymbol interference (ISI), the MAFIA results are compared to the system level analysis tool, Signal Processing Workstation (SPW), using high order modulation schemes including 16 and 64-QAM.
Document ID
20030010295
Acquisition Source
Glenn Research Center
Document Type
Conference Paper
Authors
Kory, Carol L.
(Analex Corp. Cleveland, OH United States)
Andro, Monty
(NASA Glenn Research Center Cleveland, OH United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2002
Subject Category
Electronics And Electrical Engineering
Report/Patent Number
AIAA Paper 2002-1896
Meeting Information
Meeting: 20th AIAA International Communication Satellite Systems Conference and Exhibit
Location: Montreal, Quebec
Country: Canada
Start Date: May 12, 2002
End Date: May 15, 2002
Sponsors: American Inst. of Aeronautics and Astronautics
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available