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Keywords: Power Line C a r r i e r (PLC), Frequency Hopping (FH), Channel Characteristics A b s t r a c t -Power Line C a r r i e r (PLC) communication systems p r o v i d e electric u t i l i t i e s w i t h important communication l i n k s t o implement load management and d i s t r i b u t i o n automation. Based o n a discussion o f t h e channel characterist i c s and t h e design objective o f a high overall l i n k availability it i s shown t h a t a f r e q u e n c y h o p p i n g (FH) communication system u s i n g phase s h i f t k e y i n g (PSK) modulation can overcome t h e problems o f t h e more traditional narrowband communication systems. T h e design parameters o f such a system a r e t h e n discussed. T h e performance i s evaluated and measurement r e s u l t s in testbeds and o n t h e power mains are p r esented. I n t r o d u c t i o n Power Line C a r r i e r (PLC) communication systems p r o v i d e electric u t i l i t i e s w i t h important communication l i n k s t o implement load management and d i s t r i b u t i o n automation. A PLC system has several advantages o v e r o t h e r solutions as e.g. telephone l i n k s : T h e PLC system can potentially reach a n y p o i n t in t h e power n e t w o r k and i s always u n d e r complete control o f t h e utility, o n l y t o mention t h e p r o b a b l y most important advantages. Such a system i s a v i t a l s u p p o r t in a u t i l i t y ' s e f f o r t t o b e t t e r u t i l i s e t h e e x i s t i n g power generating and d i s t r i b u t i o n capacity as t h e b u i l d i n g o f new power plants and d i s t r i b u t i o n lines becomes more and more d i f f i c u l t f o r economic and political reasons.In o r d e r t o s e r v e t h e above purpose t h e communication system must p r o v i d e a high link availability despite t h e unpredictable transmission characteristics o f t h e signal p a t h . In addition, t h e transmitted signal power must b e v e r y low t o make a system w i t h many terminals economically feasible.T h e e x i s t i n g r i p p l e control systems implement v p r y simple one-way communication l i n k s u s i n g t h e power lines as t h e communications channel [I]. Such systems need a large transmit power a n d are limited t o v e r y low data rates. These t w o disadvantages make such a system unsuitable as communications medium in a modern process control system which relies heavily o n two-way data exchanges w i t h i n t h e data network. Many attempts have been made t o develop power line c a r r i e r (PLC) communication systems w i t h increased data r a t e a n d lower t r a n s m i t power 12-10]. Improvements have been obtained b y increasing the receiver s e n s i t i v i t y . T h e signaling format was taken from telephone modems, most often Frequency S h i f t Keying (FSK) o r Phase S h i f t Keying (PSK) w i t h o u t a n y attempt t o adapt it t o t h e v e r y special channel characteristics. T h e available channel in a PLC system i s v e r y d i f f e r e n t f r o m ...

Übersicht: Das elektrische Verteilnetz ist schlecht geeignet zur Übertragung schmalbandiger Datensignale. Mit Frequenzhüpfer-Spreizbandsignalen (FH) kann die Verbindungssicherheit wesentlich erhöht werden, insbesondere wenn Phasenumtastung (PSK) und kohärente Detektion benützt werden. Die inhärente Inkompatibilität zwischen FH und PSK kann durch Mehrfachübertragung überwunden werden. Die erreichbare Übertragungssicherheit über den schlimmstmöglichen Kanal wird berechnet und verglichen mit jener eines Schmalbandsystems. Abstract: Frequency Hopping (FH) combined with Phase Shift Keying (PSK) is an optimum transmission method for difficult channels as e. g. the electrical power distribution lines. The inherent incompatibility between FH and PSK can be overcome by diversity transmission and coding. Performance results are given for selected channels with an optimum jammer. Für die Dokumentation: Digitale Datenübertragung / Frequenzhüpfen / Phasenumtastung / Mehrfachübertragung / Störer / Elektrisches Verteilnetz

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