Abstract: A method for providing a sample-rate conversion (“SRC”) filter on an input stream of sampled data provided at a first rate, to produce an output stream of data at a second rate different from the first rate. The input stream of sampled data is operated on with a first low-order interpolation filter routine to produce a first stream of intermediate data. The first stream of intermediate data is operated on with a first simplified interpolation filter routine, having a substantially small number of operations to calculate the coefficients thereof, to produce a second stream of intermediate data. The second stream of intermediate data is operated on with a first decimating filter routine to produce the output stream of data.

Abstract: A digital signal system (100) for determining an approximate logarithm of a value of x having a base b. The approximate logarithm includes an integer portion (i) and a decimal portion (f). The system comprises an input (12) for receiving a signal, and circuitry (18) for measuring an attribute of the signal. The attribute relates at least in part the value of x. The system further comprises circuitry (104) for identifying a bounded region within which x falls. The bounded region is one of a plurality of bounded regions, where each of the plurality of bounded regions corresponds to a different value of an integer n and is bounded on a lower side by bn and on a higher side by bn+1. Additionally, the identified bounded region identifies the integer portion of the approximate logarithm.

Abstract: A dithered offset correction method wherein, according to a first embodiment, updates are made of the offset correction during each iteration and, after four iterations, the offset for each pixel or detector element is updated from all of its neighbors to provide faster convergence than is obtainable by the prior art. In accordance with a second embodiment, the offset for each detector element is updated for every iteration and, for each update, the update is made with information from an entire row or an entire column of data. After four iterations, each offset has been updated with information from every detector element in the focal plane array. This provides even more rapid convergence compared to the prior art.