September 1994, Volume 3, Number 3
Comparison of Adaptive Antenna Arrays Controlled by Gradient Algorithms
The paper presents the Simple Kalman filter (SKF) that has been designed for the control of digital adaptive antenna arrays. The SKF has been applied to the pilot signal system and the steering vector one. The above systems based on the SKF are compared with adaptive antenna arrays controlled by the classical LMS and the Variable Step Size (VSS) LMS algorithms and by the pure Kalman filter.
It is shown that the pure Kalman filter is the most convenient for the control of the adaptive arrays because it does not require any a priori information about noise statistics and excels in high rate of convergence and low misadjustment. Extremely high computational requirements are drawback of this filter. Hence, if low computational power of signal processors is at the disposal, the SKF is recommended to be used.
Computational requirements of the SKF are of the same order as the classical LMS algorithm exhibits. On the other hand, all the important features of the pure Kalman filter are inherited by the SKF.
The paper shows that presented Kalman filters can be regarded as special gradient algorithms. That is why they can be compared with the LMS family.
Atmospheric Optical Communications
This article contains a description of a digital atmospheric optical link (DAOL). DAOL may find LAN applications as bridger between buildings containing cable subnetworks or as temporary quick-connects for which cable runs are initially unavailable.
J. Cajka, F. Fencl
New Version of the COCO Program
The new version of the COCO program enables the analysis of linear circuits in symbolical, symbolic numerical or in semi-symbolical form. Simple synthesis problems can also be solved with the aid of this program. Several examples illustrate the use of the program for circuit analysis and synthesis. Modern network elements (trans-impedance operational amplifier, current conveyors) are built in the program.
J.Brzobohaty, J. Pospisil, Z. Kolka
DC Analysis of an Ideal Diode Network Using Its Decomposed Piecevise-Linear Model
A new method of finding the operating points in circuits containing ideal diodes which utilizes the decomposed form of the state model of an one-dimensional piecewise-linear (PWL) system is developed. The universal procedure shown gives all the existing solutions quite automatically.
Z. Kolka, V. Michalek
Digitally Controlled Linear Four-Port Network
The paper deals with the design of a universal linear multipart. The circuit is based on digitally controlled multiple voltage-controlled voltage sources (MVCVSs). The main advantages of this control are accuracy, invariability, and very small area requirements. The whole system is simply connected to a PC via its parallel port. This multipart can generally be used as a building block for any model of a nonlinear dynamic system, namely for the piecewise-linear (PWL) model in both explicit and implicit forms.
Function Generator of Programmable Waveforms with Very Long Period Controlled by the Input Signal
The paper deals with design of slow generator of periodic waveforms the shape of which can be changed. The generator with the period adjustable by control signal could provide wide application.