Interference dynamics considerations in digital radio performance estimation

A series of algorithms that significantly extend the range of control for decision-directed structures are presented. Experimental results show that increased control ranges of approximately 20 dB can be obtained for 64-QAM systems. The algorithms can eliminate digital radio outage due to hysteresis during dispersive multipath fading and allow for enhanced control of cross-pol interference cancelers in dual-polarized digital radio systems. The performance of 64-QAM digital radios utilizing these techniques verifies that the substantial improvements predicted by theory are realizable. Examples of performance improvements with thermal noise, FM interference, and multipath fading are given to demonstrate the power of the algorithms. Examples taken from standard production AT&T DR6-30-135 digital radio show that timing and carrier synchronization are easily maintained for 64 QAM systems at signal-to-noise ratios approaching 0 dB. The results can be applied to other communications systems and may eliminate data training sequences in many applications such as voice band modems. >

This research aims to examine the existence of RRI Mataram's form of broadcasting in the digital era. RRI Mataram is the only government-owned radio in the city of Mataram which in order to keep up with developments in information and communication technology of course requires innovation in the form of broadcasting so that it continues to exist and does not lose RRI Mataram's loyal listeners. The focus of the research is on aspects of RRI Mataram's broadcasting form in the digital era. This research was designed in a qualitative descriptive manner, using media convergence theory. The results of the research show that RRI Mataram's form of broadcasting communication in the digital era uses three forms of radio which were initially innovated to become digital radio. The three forms are analog radio, digital radio and online radio. Analog radio was the first form of radio which still exists today. Analog radio uses analog signals which can be affected by various factors, such as electromagnetic interference, damage to components, and weather. Secondly, digital radio is radio which in its use uses digital technology to share information with a wide audience. The information which was originally audio is then converted into digital data and then received by the radio. Digital signals have better sound quality than analog signals. The third is internet radio or online radio, internet radio, namely radio that uses an internet connection in its broadcast communication process. Internet radio has a streaming media to provide continuous audio channels that are not found on conventional radio in general. Internet radio is also often called web radio, or net radio.

Outage in digital microwave radio systems during multipath fading is highly correlated with the channel amplitude dispersion. This characteristic is exploited in a new digital microwave radio system measurement technique which yields dispersion signatures. These dispersion signatures can be readily applied to assess the effects of time varying channels on digital radio equipment. Thus, dispersion signatures can be used for in-service monitoring of equipment operation during actual fading. Routine maintenance assessment and laboratory evaluation of digital microwave radio equipment can also be readily carried out. The laboratory evaluation results can be used for system design both with and without diversity.

This paper describes a new digital wireless data acquisition system that cam be used to measure electro-magnetic interference (EMI) in power stations or other similar harsh environments. It comprises of a remote acquisition unit (RAU), a wireless data communication network (WDCN) and a PC-based control platform. Using digital technology, the system transmits a signal (transient or steady state) of short duration & wide band through a narrowband channel over a longer duration. The RAU captures and stores the EMI signals and sends the information to the control platform at a convenient time, using the wireless data communication network. The wireless data communication network acts as a bi-directional data communication link between the RAU & the control platform. It is based on Bluetooth technology and has a point-to-multipoint topology. The RAU serves as the acquisition function of a digital storage oscilloscope (DSO) while the control platform carries out the display & control function of a DSO. The whole system, as such, may be regarded as a 'computerised wireless oscilloscope'.

This paper considers the application of constant-amplitude, partial-response, continuous-phase modulation with simple near-optimum receivers to cellular digital mobile radio systems. These smoothed modulation schemes have low spectral sidelobes and narrow main lobes. A combiner for time-division retransmission systems with space diversity is given for continuous-phase modulation. Cochannel interference and adjacent-channel interference are calculated for continuous-phase modulation in cellular systems with frequency reuse. The efficiency of 3RC and 4RC modulations with space diversity is evaluated for conventional cellular systems.

Statistical characterisation of bacterial wild-type MIC value distributions and the determination of epidemiological cut-off values

Simultaneous measurements of microwave fading and lower atmospheric conditions were carried out in Georgia in 1986 as a part of the continuing effort to study the line‐of‐sight digital radio performance. Acoustic sounding was a principal means of exploring the mechanism that causes dispersive fading. It was found that dispersive multipath fading occurs during nights with strong radiation inversion accompanied by a subsiding air mass. Subsidence inversion causes dispersion, and the origin of the air mass affects the mean received power level under multipath propagation conditions. When the height of the nocturnal boundary layer coincides with the height of the ground‐based radiation inversion layer and is at 100–150 m, fading is heavy, active, and dispersive for a 57‐km path with both transmitting and receiving antennae at 60 m above grade. Case studies of the significant episodes are presented, and the statistics of the different types of fading associated with the types of meteorological conditions are summarized for the 5‐month study period.

In microwave digital radio transmission, waveform distortion due to frequency selective fading becomes a dominant factor of degradation. To evaluate the degradation of different systems in a unified way, the waveform factor is defined first. With the aid of concept “waveform factor,” the eye aperture is easily obtained. We also evaluate the waveform factors for various modulation schemes. Next, on the basis of the relation between propagation parameters and waveform factor in two‐ray fading, the estimation formula of the outage probability for various digital radio systems in line‐of‐sight propagation is derived. The proposed factor is determined uniquely by system parameters, such as modulation scheme, system impulse response, and symbol rate. With the aid of this factor, digital radio system performance during multipath fading is easily evaluated.

Some statistical characteristics of transmission errors associated with a digital radio channel in the absence of protection switching are examined. It is demonstrated that the occurrence or nonoccurrence of bit errors in an unprotected digital radio channel is a dependent stochastic process. Additionally, it is shown that the distribution of the number of errored seconds in a given time interval depends upon the cause of the errors. Multipath fading, for example, will cause equal numbers of severely errored seconds and nonseverely errored seconds. On the other hand, equipment failures and maintenance activity cause more severely errored seconds than nonseverely errored seconds. These signature characteristics are related to the lack of independence in the occurrence of bit errors in adjacent seconds. The results discussed have important implications in the development of performance models for digital radio. In particular, they demonstrate the need for a controlled experiment dedicated to the study of the correlation structure that governs the occurrence of bit errors. >

This paper is focused on the aspects of diversity schemes and reception methods that were rare or never discussed in the technical literature. It clarifies ambiguities and corrects inaccuracies related to them, examines the influence of digital technology, and analyzes the theory and realization of maximum ratio combining (MRC) as well as related methods in digital radios, some of which are software defined and cognitive ones (SDRs and CRs). Among other subjects, it identifies areas where spread-spectrum (SS) signals are preferable in diversity schemes; explains similarity and differences between MRC in space diversity and adaptive beamforming and nulling as well as between MRC and optimal linear filtering; present examples of MRC realization; shows that classical MRC algorithm has to be generalized when the estimation of characteristics of signals and non-white noise is required; and describes joint use of MRC and optimal linear filtering for the reception of SS signals.

Measuring radio pulses from cosmic ray air showers offers various new opportunities. New digital radio receivers allow measurements of these radio pulses even in environments that have lots of radio interference. With high bandwidth ADCs and fast data processing it is possible to store the whole waveform information in digital form and analyse transient events like air showers even after they have been recorded. Digital filtering and beam forming can be used to suppress the radio interference so that it is possible to measure the radio pulses even in radio loud environments. LOPES is a prototype station for the new digital radio interferometer LOFAR and is tailored to measure air showers. For this it is located at the site of the KASCADE-Grande air shower experiment. Already with the first phase of LOPES we have been able to measure radio pulses from air showers and show correlations between the radio pulse height and air shower parameters. The first part gives an introduction and presents the science results of LOPES, while the second part presents the hard- and software that enables LOPES to detect air short pulses.

Characteristics of L-band radio frequency interference detected via the soil moisture active passive radiometer in China and its offshore areas

Polarization diversity techniques have not received as much attention as others due to the significant difference in mean signal level between copolarized and cross-polarized branches when one polarization is transmitted. However, multiple- input–multiple-output (MIMO) systems where the multipath fading is only partially correlated could use polarization diversity to provide a high diversity gain. Hence there is a need to fully understand the role of true polarization diversity in such systems. In this letter, progressive (true) polarization diversity performance for 3 3 MIMO systems under Rayleigh-fading environments is evaluated through simulations and measurements. True polarization diversity was found to be as significant as spatial diversity at improving diversity gain, and hence MIMO system capacity.

The objective of this work is to numerically estimate the fraction of Reserves assigned to each Reserves category of the PRMS matrix through a cumulative distribution function. We selected 38 wells from a Permian Basin dataset available to Texas A&M University. Previous work has shown that Swanson's Mean, which relates the Reserves categories through a cdf of a normal distribution, is an inaccurate method to determine the relationship of the Reserves categories with asymmetric distributions. Production data are lognormally distributed, regardless of basin type, thus cannot follow the SM concept. The Gaussian Quadrature (GQ) provides a methodology to accurately estimate the fraction of Reserves that lie in 1P, 2P, and 3P categories – known as the weights. Gaussian Quadrature is a numerical integration method that uses discrete random variables and a distribution that matches the original data. For this work, we associate the lognormal cumulative distribution function (CDF) with a set of discrete random variables that replace the production data, and determine the associated probabilities. The production data for both conventional and unconventional fields are lognormally distributed, thus we expect that this methodology can be implemented in any field. To do this, we performed probabilistic decline curve analysis (DCA) using Arps’ Hyperbolic model and Monte Carlo simulation to obtain the 1P, 2P, and 3P volumes, and calculated the relative weights of each Reserves category. We performed probabilistic rate transient analysis (RTA) using a commercial software to obtain the 1P, 2P, and 3P volumes, and calculated the relative weights of each Reserves category. We implemented the 3-, 5-, and 10-point GQ to obtain the weight and percentiles for each well. Once this was completed, we validated the GQ results by calculating the percent-difference between the probabilistic DCA, RTA, and GQ results. We increase the standard deviation to account for the uncertainty of Contingent and Prospective resources and implemented 3-, 5-, and 10-point GQ to obtain the weight and percentiles for each well. This allows us to also approximate the weights of these volumes to track them through the life of a given project. The probabilistic DCA, RTA and Reserves results indicate that the SM is an inaccurate method for estimating the relative weights of each Reserves category. The 1C, 2C, 3C, and 1U, 2U, and 3U Contingent and Prospective Resources, respectively, are distributed in a similar way but with greater variance, incorporated in the standard deviation. The results show that the GQ is able to capture an accurate representation of the Reserves weights through a lognormal CDF. Based on the proposed results, we believe that the GQ is accurate and can be used to approximate the relationship between the PRMS categories. This relationship will aid in booking Reserves to the SEC because it can be recreated for any field. These distributions of Reserves and resources other than Reserves (ROTR) are important for planning and for resource inventorying. The GQ provides a measure of confidence on the prediction of the Reserves weights because of the low percent difference between the probabilistic DCA, RTA, and GQ weights. This methodology can be implemented in both conventional and unconventional fields.

Considers free-space propagation and discusses deviations from it due to effects of terrain, atmosphere, and precipitation Describes multipath fading due to ground reflection or atmospheric refraction and characterizes it with fading parameters and statistical models Describes empirical path loss models Explains digital radio performance can be improved by proper choice of antennas, diversity, and adaptive equalization Discusses the effects of frequency allocations on digital radio capacity and system planning Lists the procedures for calculating link performance or determining link design parameters