Chapter 2 The Electra Radio

This chapter provides an overview of the Electra radio [1]. This is the first programmable software radio that has been developed for space missions. The radio currently accommodates digital binary phase shift keying (BPSK) modulation with both suppressedand residual-carrier capabilities. The radio is designed to operate over a wide range of data rates from 1 kilobit per second (kbps) to 4 megabits per second (Mbps) and must accommodate frequency uncertainties up to 20 kHz with navigational Doppler tracking capabilities. As such, it is highly programmable and incorporates efficient front-end digital decimation architectures to minimize power consumption requirements. The Electra radio uses field programmable gate array (FPGA) technology to provide the realtime and programmable capabilities. Emphasis in this chapter is focused on the programmable features of the software algorithms implemented in the Electra transceiver as well as the hardware functional specifications. The objective of the Electra radio, which is based on the original Micro Communications and Avionics Systems (MCAS) prototype [2], is to develop programmable telecommunications systems to meet the unique needs of the National Aeronautics and Space Administration (NASA) for low-power space and planetsurface communications. NASA is moving into an era of much smaller space exploration platforms that require low mass and power. This new era will usher in increasing numbers of miniature rovers, probes, landers, aerobots, gliders, and multiplatform instruments, all of which have short-range communications needs (in this context short-range is defined as non-deep-space links). Presently these short-range (or in situ) communications needs are being met by a combination