Modified Barker and Huffman Sequences in Combination Codes

lt is possible that usable combination codes can be obtained if Barker and Huffman sequences are chosen as the inner and outer codes. lt is shown that an improvement in either energy efficiency or time sidelobe structure will result either from a modification of a Huffman sequence or from a modification of a Barker sequence. Results are given for a combination code of length 91, with inner and outer codes of length 7 and 13.     

Which way is the bookstore? A closer look at the judgments of relative directions task

We present a detailed analysis of a widely used assay in human spatial cognition, the judgments of relative direction (JRD) task. We conducted three experiments involving virtual navigation interspersed with the JRD task, and included confidence judgments and map drawing as additional metrics. We also present a technique for assessing the similarity of the cognitive representations underlying performance on the JRD and map-drawing tasks. Our results support the construct validity of the JRD task and its connection to allocentric representation. Additionally, we found that chance performance on the JRD task depends on the distribution of the angles of participants’ responses, rather than being constant and 90 degrees. Accordingly, we present a method for better determining chance performance.     

Modified Barker Code Approximating Huffman's Impulse-Equivalent Sequence

It is shown by use of D.A. Huffman's polynomial representation for a finite sequence of contiguous pulses in a pulse train that Barker's binary-coded sequences can be modified, by a weighting of pulse amplitudes, to a condition where time sidelobes in the pulse compressed signal are substantially reduced. In such a pulse amplitude modification there is a sacrifice in pulse train energy since each pulse does not have maximum energy. Results here are provided for Barker's sequence of length 13 only.