ΜΕΛΕΤΗ ΚΑΙ ΥΠΟΛΟΓΙΣΜΟΣ ΤΗΣ ΕΠΙΘΥΜΗΤΗΣ ΠΡΟΠΑΡΑΜΟΡΦΩΣΗΣ ΓΙΑ ΤΗΝ ΔΙΟΡΘΩΣΗ ΤΗΣ ΕΙΣΑΓΟΜΕΝΗΣ ΠΑΡΑΜΟΡΦΩΣΗΣ ΣΕ ΜΗ ΓΡΑΜΜΙΚΟΥΣ ΠΟΛΥΕΠΙΠΕΔΟΥΣ ΨΗΦΙ...

THE NEED TO TRANSMIT MORE AND MORE INFORMATION VIA DIGITAL TERRESTRIAL AND SATELLITE LINKS HAS BECOME AN URGENT DEMAND. BECAUSE OF THE LIMITED BANDWIDTH AVAILABILITY, THE CURRENT TREND IS TO IMPROVE THE SPECTRUM EFFICIENCY OF THE MICROWAVE SYSTEMS, USING M-ARY DIGITAL SCHEMES SUCH AS M-ARY QAM [1.4]. IN FACT M- ARYQAM SCHEMES PRESENT MUCH BETTER POWER/BANDWIDT EFFICIENCY THAN THE EQUIVALENT M-ARY PSK IN AWGN ENVIRONMENT. MOREOVER, COCHANNEL IMMUNITY OF M-ARY QAM IS SUPERIOR TO THAT OF M-ARY PSK BUT IN THE CONTRAST THEY ARE ESPECIALLY SUSPECTIBILETO NONLINEAR DISTORTION. AS IS KNOWN, TWT AMPLIFIERS, USED IN A SATELLITE TRANSPONDER OR A TERRESTRIAL REPEATER, ARE USUALLY WORKING NEAR SATURATION BECAUSE OF HIGH SYSTEM GAIN REQUIREMENTS [3,4]. IN THIS MODE OF OPERATION THE AMPLIFIEREXHIBITS AM/AM AND A CONVERSION EFFECTS, CAUSING SEVERE DEGRADATION IN THE PERFORMANCE OF M-ARY QAM SYSTEMS WITH INCREASING M. THIS IS ESPECIALLY TRUE WHEN GAUSSIAN CHANNEL NOISE APPEARS BOTH AT THE INPUT AND THE OUTPUT OF THE TRANSPODER'S NONLINEAR OPERATING TWTA [3,8,12]. IN THIS CASE THE PRESENCE OF AM/AM AND AM/PM DISTORTION PRODUCE A COMPLEX SPECTRUM OF CONVERSION PRODUCTS WHICH RESULT FROM THE COMBINED EFFECT OF THE NONLINEAR PROCESSING OF THE AMPLITUDE MODULATEDSIGNAL AND THE CHANNEL NOISE. (SHORTENED)

Grantor dc:publisher

Αριστοτέλειο Πανεπιστήμιο Θεσσαλονίκης (ΑΠΘ)

Year dc:date

1989

Author dc:creator

• Γούτα, Μαρία

• DIGITAL SATELLITE COMMUNICATIONS
• LINEARIZATION TECHNIQUES (PREDISTORTION)
• M-ARY QAM MODULATION SCHEMES
• ΠΟΛΥΕΠΙΠΕΔΕΣ ΥΒΡΙΔΙΝΕΣ ΤΕΧΝΙΚΕΣ ΔΙΑΜΟΡΦΩΣΗΣ
• Τεχνικές γραμμικοποίησης
• ΨΗΦΙΑΚΕΣ ΔΟΡΥΦΟΡΙΚΕΣ ΕΠΙΚΟΙΝΩΝΙΕΣ
• Engineering and Technology
• Electrical Engineering, Electronic Engineering, Information Engineering
• Επιστήμες Μηχανικού και Τεχνολογία
• Επιστήμη Ηλεκτρολόγου Μηχανικού, Ηλεκτρονικού Μηχανικού, Μηχανικού Η/Υ

Language dc:language

gre

Identifier

10.12681/eadd/1460

OAI identifier oai:identifier

oai:10442/1460