A very compact and rugged 2.5-D integrated data logger has been built and tested. The data logger is capable of measuring accelerations exceeding 70 000 g. Microcontroller and flash memory as bare dies have been mounted onto a silicon interposer with through silicon vias using anisotropic conductive film and Au stud bump bonding. A microelectromechanical system accelerometer is mounted onto the interposer, using a robust customized flip-chip mounting approach. The interposer is mounted into a 16-pin leadless chip carrier package using isotropic conductive adhesive, where the conductive part is made of metallized polymer spheres. The ceramic package was mounted onto an application printed circuit board (PCB) with filters, power management, and an interface contact, using soldered plastic core solder balls (PCSBs). The diameter of the data logger is less than 9 mm, and the height is approximately 5 mm. The data logger fits within 12.7-mm (0.50 cal.) projectile, and acceleration measurements have been performed during firing, flight, and recovery. The measured accelerations have been verified by comparing the calculated projectile muzzle velocities with Doppler radar measurements.

Using a framework that lies at the intersection of communications, estimation and control, this work considers feedback communication over noisy Gaussian feedforward as well as unconstrained feedback Time Dispersive Channels (TDCs), and presents a linear scheme that reduces transmission delay for a fixed encoder dimension. The approach is based on Liu and Elia's feedback scheme, that is generalized in this paper to accommodate a noisy TDC in the feedback link, showing the usefulness of the technique despite the noisy feedback. This technique also mitigates the inherent numerical instability problem in Liu and Elia's original system, and does not require the solution of a non-convex optimization problem to find the optimal encoder/decoder for a given pair of feedforward and feedback channels. These advantages are achieved at the expense of an increase in transmission power, that becomes small when the SNR increases. Computer simulation results show that the new scheme reduces significantly the transmission delay, while still providing rates at high SNR that are close to those achieved by an optimal linear encoder. These features make the new coding scheme attractive for practical applications.