Martin J. Agan

A highly miniaturized, battery operated, commandable, digital wireless camera

This paper discusses the design, development, testing, and demonstration of a highly miniaturized battery operated, digital wireless camera. The miniature wireless camera receives commands transmitted from a remote base station requesting it to take one or more frames of data, and broadcasts the digital image data to the base station receiver for display. The camera uses a complementary metal-oxide-semiconductor (CMOS) active pixel image sensor (APS) that achieves noise performance comparable to a charge-coupled device (CCD) with orders of magnitude better power consumption performance. The image sensor is integrated with a wireless communications transceiver, antennas and batteries into a stand alone miniature package. The results of a three year development effort are described.

A FREQUENCY OFFSET ESTIMATION AND COMPENSATION ALGORITHM FOR K/Ka‐BAND COMMUNICATIONS

This paper presents a new open-loop technique for estimating and correcting Doppler frequency shift in K/Ka-band communication systems with special reference to the advanced communications technology satellite (ACTS) mobile terminal (AMT) modem, which utilizes square-wave pulse-shaped, binary differential phase shift-keyed (DPSK) modulation. The novelty of this estimation scheme is that it exploits the Doppler-induced phase shift over a fraction of a symbol interval to provide an estimate of the Doppler offset, without requiring symbol synchronization. Furthermore, by utilizing time-differential detection (delay-and-multiply), the proposed technique can tolerate much larger frequency offsets than existing open- or closed-loop techniques. Analytical results are provided for the variance of the above estimator and the error probability performance of the AMT is evaluated in the presence of the Doppler correction. Practical design considerations are also discussed, including a method for modifying the front end, digital bandlimiting filter in such a way that Doppler bias effects in the new estimator are eliminated. Simulation results reveal that, in general, performance improves with increasing data rates, i.e., the new frequency offset estimation/compensation algorithm induces a degradation from ideal of approximately 1 dB at a 6 dB energy per data symbol (bit) and a 2.4 kbps data rate. However, there is no appreciable degradation when the data rate is increased to 9.6 or 19.2 kbps.

ACTS AERONAUTICAL EXPERIMENTS

This paper discusses a series of aeronautical experiments that utilize the advanced communication technology satellite (ACTS). As part of the ongoing effort to investigate commercial applications of ACTS technologies, NASAs Jet Propulsion Laboratory and various industry/government partners have developed a series of experiments that utilize the ACTS mobile terminal (AMT) 1 and the broadband aeronautical terminal 1 to investigate aeronautical uses of the ACTS. This paper discusses these experiments including the experiment configurations, technologies, results and future implications.

Micro communications and navigation system for short-range space and planet-surface communications

This paper provides an overview of the communications system that is being developed as part of the Micro Communications and Avionics Systems (MCAS). The first phase (MCASl) effort is being focused on a digital, binary phase shift key (BPSK) system with both suppressed and residual carrier capabilities. The system is being designed to operate over a wide range of data rates from 1 kbps to 4 Mbps and must accommodate frequency uncertainties up to 10 kHz with navigational Doppler tracking capabilities. As such, the design is highly programmable and incorporates efficient front-end digital decimation architectures to minimize power consumption requirements.’ The MCASl design uses field programmable gate array (PPGA) technology to prototype the real time MCASl communications system. Ultimately, this design will migrate to a radiation-hardened, application-specific integrated circuit (ASIC). Specific emphasis in this article is focused on the digital front end and BPSK demodulation portions of the MCAS 1 receiver.