Influence of the transmission medium quality on the automatic meter reading system capacity

This article determines the influence of the telecommunication transmission medium's quality, expressed by the probability of failed single-try transmission, on the capacity of the automatic meter reading system. Failed message transmission leads to the necessity of retransmission, with possible multiple retransmissions. This causes the prolongation of average time required for collecting the information from the great population of meters, reducing the capacity of reading expressed in meters per hour being read. This work continues the analysis published by S. Mak et al. (1995), but also expands it by including the influence of the transport medium's limited quality. In the automatic meter reading systems, one can use networks with radio relays and power line carrier (PLC)-based devices. Our analysis is partly based on the assumption that the PLC medium has much lower quality than the radio, causing most of the transmission errors occur on the PLC itself. The result of the analysis is the processing prolongation factor g, which depends on the statistic parameter of single-try retransmission probability only. This kind of model enables the explanation of disproportion amongst the local probabilities of retransmission and the general probability observed in the entire network, as recognized and documented by L. Selander (1999) . In the end, we determine the automatic system's reading capacity limit.     

Signal propagation modeling in power-line communication networks

In this paper, we present a propagation model for the power-line communication (PLC) networks, based on the frequency-domain analysis. First, we set a simple two-port model of the network. Then, we calculate a complex attenuation factor from z-parameters, expressed in terms of impedances, easily calculable/measurable from the network ports. We explain simultaneously calculation and measurement methods based on the same principle, and then compare the results with direct measurements performed in the network designed for this purpose. We provide all of the elements for a simple end efficient propagation model. They include propagation by crosstalk between different circuits in, for example, three-phase networks, as well as the influence of the loads connected to the ports of different circuits in such networks. We have concluded that the model is suitable for PLC channels simulations that give very accurate results and enable modeling of wide-band channel characteristics.     

Large-shift constant-amplitude phase modulators

This article presents the method of realization of phase modulators characterized by the constant amplitude of the modulated signal and by the linear dependence of its phase shift in a large range on the input modulation signal. This is achieved by appropriate modulation signal processing in the base band. The inherent nonlinearity stemming from imperfect processing has been analyzed through the computer simulations of various devices with either analog or digital processing. Only the number of bits in one digital sample of the input modulation signal limits the maximum phase deviation achievable in the device with digital processing. An example shows how to get a phase deviation of ±16π through 12-bit quantization of the input voltage, with the inherent nonlinearity better than 1% in the whole range, and better than 0.01% in 95% of the whole range