Joshua P. Bruckmeyer

Adaptive calibration of wideband digital beam formers with injection calibration

This paper presents a closed-loop internal adaptive calibration method for wideband digital beam formers in phased array applications. The channels are time aligned and calibrated before beam forming using an internal network for illumination and correction of the elemental electronic channels. This approach lowers the cost of wideband phased arrays by eliminating manual factory tuning. The internal calibration network enables calibration during operation without the implicit electromagnetic compatibility (EMC) concerns of a cooperative radiating source. The approach facilitates correcting for age related changes from the initial factory calibration, and for the inherent factory calibration residual errors. Measured data from an existing 22-phase center elemental digital beam former array was used to evaluate the method. The channel response was extracted and bit error rate (BER) was evaluated using a simulation test bench. The results show two orders of magnitude improvement in BER over a narrow band method based on singular value decomposition.

Radios, payloads, & onboard processing made easy

The advent of reprogrammable software defined payloads has dramatically reduced the cost and complexity of developing space radios and remote sensing payloads. Over the last several years, Harris has been developing its AppSTARTM product line of reprogrammable software defined radios, including the NASA CoNNeCT SDR flying as part of NASAs SCaN testbed on the International Space Station. Since the CoNNeCT mission was launched in 2012, Harris has delivered over 100 software defined payloads (SDP), including those functioning as secondary hosted payloads for a variety of commercial and government applications. Looking to the future, investments were made in the second generation of Harris AppSTAR™ through radiation testing the latest commercial processors and packaging them together with radiation tolerant mitigation circuitry. Our new micro-SDR (μSDR) is packaged into a smaller volume, but yields significantly higher processing horsepower. The μSDR is capable of high rate communications capability over 1 Gbps, and its first launch is planned for mid-2017. The flexibility of the Harris AppSTAR™ architecture enables SDPs to be quickly developed to support communication and remote sensing mission needs. A variety of missions can be supported through application of SDP/radio technology which reduces the cost, risk, and schedule of achieving mission success.

Adaptive Digital Beamformer Autocalibration Using an Injected Noise Source

This paper presents a wideband closed-loop relative adaptive calibration method for digital beamformers in phased array applications. Using an internally distributed and injected additive white Gaussian noise source, we equalized the channels relative to a selected channel before beamforming. This relative injection method has a size, weight, and power (SWaP) advantage compared with an absolute method where a copy of the illumination waveform is used as the reference signal. Measured data from an existing 22-phase-center elemental digital beamformer array were used to evaluate the relative method against existing absolute methods. The channel response was extracted and the bit error rate was evaluated using a simulation test bench. A parametric conceptual design was also performed to evaluate the relative SWaP between the relative and absolute methods. The results show that the relative method is 17.6 times smaller, uses 1.3 times less power, and is 2.4 times lower in cost than the absolute method. The results also show that the relative calibration method can be as effective as an absolute method, given that the injected waveform has a higher signal-to-noise ratio than the ambient scene.