PCM synchronization by word stuffing

When a transmitted word, consisting of a number of pulses, is detected and removed from the data stream, the space left by the removal is eliminated by a memory buffer. This eliminates the need for a clock synchronizer thereby removing instability problems

Multichannel telemetry system

A two-channel telemetry system is described in which one channel is used for high-rate data and the other channel for low-rate data communication. In the transmitter a signal, which subsequently phase modulates a carrier, is produced which is a function of at least the high-rate data, the low-rate data and the frequency of the subcarrier of the low-rate channel. In the receiver which includes a phase-locked loop, the high-rate data is detected off the receiver inphase channel output and the low-rate off the quadrature channel output

Interplex modulation and a suppressed-carrier tracking loop for coherent communications systems

Simple addition to hardware and new mode of operation of transmitter and receiver in coherent, PCM/PSK/PM configuration greatly improves channel efficiency. Procedure reduces amount of power lost to intermodulation products

TBI Contusion Segmentation from MRI using Convolutional Neural Networks

Traumatic brain injury (TBI) is caused by a sudden trauma to the head that may result in hematomas and contusions and can lead to stroke or chronic disability. An accurate quantification of the lesion volumes and their locations is essential to understand the pathophysiology of TBI and its progression. In this paper, we propose a fully convolutional neural network (CNN) model to segment contusions and lesions from brain magnetic resonance (MR) images of patients with TBI. The CNN architecture proposed here was based on a state of the art CNN architecture from Google, called Inception. Using a 3-layer Inception network, lesions are segmented from multi-contrast MR images. When compared with two recent TBI lesion segmentation methods, one based on CNN (called DeepMedic) and another based on random forests, the proposed algorithm showed improved segmentation accuracy on images of 18 patients with mild to severe TBI. Using a leave-one-out cross validation, the proposed model achieved a median Dice of 0.75, which was significantly better (p<0.01) than the two competing methods.Comment: https://ieeexplore.ieee.org/abstract/document/8363545/, IEEE 15th International Symposium on Biomedical Imaging (ISBI 2018

On the error statistics of Viterbi decoding and the performance of concatenated codes

Computer simulation results are presented on the performance of convolutional codes of constraint lengths 7 and 10 concatenated with the (255, 223) Reed-Solomon code (a proposed NASA standard). These results indicate that as much as 0.8 dB can be gained by concatenating this Reed-Solomon code with a (10, 1/3) convolutional code, instead of the (7, 1/2) code currently used by the DSN. A mathematical model of Viterbi decoder burst-error statistics is developed and is validated through additional computer simulations

Sediment trap biases in turbulent flows: Results from a laboratory flume study

Several cylindrical and noncylindrical sediment trap designs were tested in a recirculating steady-flow flume. The laboratory study was conducted to achieve dynamic- and geometric-similarity to conditions in a specific field environment where traps eventually would be deployed. Relative (to a standard trap design) particle collection efficiencies of the traps were quantified in ∼10 cm/sec turbulent flows that were continuously seeded with particles having fall velocities of about 10−2 to 10−1 cm/sec (the upper range of silt-sized quartz sediments). The nature of flow through the trap mouths was qualitatively described using dye.The following trap biases were demonstrated in the study. For unbaffled cylinders, efficiency decreased over a range of increasing trap Reynolds number (Rt) when aspect ratio (H/D) was held constant, and efficiency increased over a range of H/D when Rt was held constant. Baffling cylinders with various H/D but constant Rt, gave mixed results. Any disturbance to flow near the trap mouth or through the trap tended to increase between-replicate variability. For unbaffled, noncylindrical traps, small-mouth, wide-body traps overcollected particles and funnel-type traps tended to undercollect particles, relative to cylinders of the same height and mouth diameter.The biases demonstrated here are for specific parameter combinations and cannot be generalized outside the range of values tested. The results do indicate that significant biased collections are possible by a variety of trap designs and may be flow-regime dependent. Trap-users thus are urged to interpret vertical flux results with caution. Further quantitative studies of trap biases for the ranges of conditions common in field trapping environments and process-oriented studies of physical trapping mechanisms are needed to determine the utility of sediment traps for flux estimates in ocean flows