Unit 1. Introduction. Adaptive filters

Text A. Adaptive Processing

Text B. Adaptive Filters. The Historical Review

Text C. Adaptive Filter Operation

Text a. Adaptive Processing

Essential Vocabulary

matched filter preceding assumption invariant quality arrangement conditioning signal training learning signal to update processor weighting parameters iterative frequency response spatial processing antenna array to steer the main lobe toward the signal to generate nulls in the beam pattern in the direction of the interfering sources priory information intended application sampled-data system explicit

–согласованный фильтр - предыдущий - допущение - неизменяемая величина - (зд.) контур - стандартный сигнал - обучающий сигнал - (зд.) корректировать - весовые параметры процессора - повторяющийся - частотная характеристика - пространственная обработка сигнала - антенная решетка - создавать на (диаграмме) главный максимум в направлении прихода сигнала - генерировать шум в направлении источников помех - предварительная информация - предлагаемое использование (применение) - система обработки импульсных сигналов - определенный, точный

Read and translate Text a using Essential Vocabulary Text a. Adaptive Processing

Conventional signal processing systems for the extraction of information from an incoming signal such as a matched filter operate in an open-loop fashion. That is, the same processing function is carried out in the present time interval regardless of whether that function produced the correct result in the preceding time interval. In other words, conventional signal processing techniques make the basic assumption that the signal degradation is a known and time-invariant quantity.

Adaptive processors on the other hand, operate with a closed-loop (feedback) arrangement. The incoming signal s(n) is filtered or weighted in a programmable filter to yield an output y(n) which is then compared against a desired, conditioning or training signal, y(n), to yield an error signal, e(n). This error is then used to update the processor weighting parameters (usually in an iterative way) such that the error is progressively minimized (i.e., the processor output more closely approximates to the training signal). Such processors fall into the two broad classes of adaptive filters (Figure 1.) and adaptive antennas.

Adaptive filters, which are the subject of this text, are concerned with the use of a programmable filter whose frequency response or transfer function is altered, or adapted, to pass the desired components of the signal without degradation and to attenuate the undesired or interfering signals, or to reduce any distortion on the input signal. Adaptive antennas employ the spatial processing in an antenna array to steer the main-lobe toward the signal and generate nulls in the beam pattern in the direction of the interfering sources. Thus they use spatial processing techniques for interference reduction.