The Ground Transmitter and Receiver

1.1 General T h e T e l s t a r ground t r a n s m i t t e r is designed to produce a 2-kw frequency-modulated signal in t h e 6-kmc b a n d , suitable for t h e transmission of television or multiplex telephony. Fig. 1 is a simplified block d i a g r a m which shows t h e basic f e a t u r e s of t h e four sections of t h e t r a n s m i t t e r : FM deviator, modulator-amplifier, t r a n s m i t t e r carrier supply, and power amplifier. T h e T e l s t a r transmission objectives 1 , 2 are similar in m a n y respects to those established for domestic microwave radio relay systems. As a result, it has been possible to use in t h e T e l s t a r t r a n s m i t t e r m a n y pieces of e q u i p m e n t designed for t h a t service. T h e FM deviator, modulator-amplifier a n d t r a n s m i t t e r carrier supply are direct a d a p t a t i o n s of u n i t s currently being m a n u f a c t u r e d for the 6-kmc TH radio relay syst e m . 3 4 5 T h e power amplifier is designed a r o u n d a 2-kw traveling-wave tube 6 developed at Bell Telephone Laboratories. 1.2 Design Considerations T a b l e I summarizes t h e transmission objectives established for the ground t r a n s m i t t e r . These are derived f r o m system objectives based, primarily, on one-way transmission of monochrome television a n d 600channel multiplex telephone. Simultaneous two-way transmission through t h e satellite, together with its restricted AGO range, deter1063 TO G R O U N D RECEIVER I F LOOP FM DEVIATOR ESASEBAND INPUT HIGHFREQUENCY MULTIPLIER FILTER -«-- A 1 LOWFREQUENCY MULTIPLIER 4 l I SLANT-RANGE INFORMATION I TRANSMITTER CARRIER SUPPLY Fig.