Design and performance of a variable rate digital demodulator for a 23/26 GHz DRS user spacecraft transponder

This paper describes the design and the performance of a variable rate digital demodulator for a 23/26 GHz DRS user spacecraft transponder. In the Ka-band, a transmission link is provided with a bandwidth of approximately 47 MHz. On this link, from ground via a DRS satellite to a user spacecraft, any data rate between 1 kbit/s and 25 Mbit/s may be used. The variable rate digital demodulator covers data rates from 1 kbit/s up to 5 Mbit/s. In a short review the DRS environment and the relevant system requirements for the digital demodulator will be summarized. On block diagram level the design of the variable rate digital demodulator is presented. The main objectives of this paper are the description of the testbed used to verify the performance of the digital demodulator and the achieved test results. For the three different data rates, 1 kbit/s, 512 kbit/s and 5 Mbit/s the results are presented