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The work reported in this research seeks to investigate the characteristics, in terms of parameters such as multipath delay spread, of the wireless broadband millimeter wave outdoor radio channel in the presence of directional antennas at both transmitter and receiver, and then to identify the optimum equalizer structures for LMCS/LMDS system receivers. This evaluation is based on a large number of measured multipath profiles of the outdoor broadband wireless channel obtained in one of the residential areas of Ottawa under both line-of-sight and non-line-of-sight conditions. The results are presented in terms of the number of feedforward taps and the feedback taps required in the feedforward and feedback filter sections of a decision feedback equalizer (DFE), at different symbol rates, for achieving the optimum solution in terms of minimum mean-square-error (MMSE) at the slicer output. In this investigation, recorded multipath profiles from the MM-wave channel are processed to extract the time-varying estimates of the channel impulse response.

A model for the prediction of millimetre-wave propagation in suburban areas is presented. This model has been developed for the purpose of investigating coverage with broadband terrestrial fixed wireless systems such as local multipoint distribution service (LMDS). The results of a comparison with field measurements conducted at 28 GHz are presented. In addition, the model is used to predict the coverage enhancement resulting from the use of non-regenerative, on-channel repeaters.

This research concerns comparing the performance of various transmission and reception alternatives for the 5-45 MHz portion of the upstream path of the return coaxial cable band. This evaluation is based on ingress noise spectra files collected over an extended period of time from various sites. This data has been used to evaluate the return band capacity as a function of sub-channel bandwidth in FDMA and TDMA/FDMA schemes. In addition, the time varying aspect of the channel is considered using variable bit rate allocation to sub-bands, as in OFDM with frequency division multiplexing. Furthermore, the same analysis is repeated for a wideband system using a decision feedback equalizer (WDFE) contending with ingress noise instead of channel distortion. This research demonstrates that using a variable channel allocation (VCA) scheme to match the time varying aspect of the channel enhances the performance over a fixed channel allocation (FCA) scheme. It also shows that a wideband system using an adaptive decision feedback equalizer (DFE) performs similar to a multi-carrier modulation (MCM) method, and that reasonable performance can be obtained by using a system of lower complexity consisting of the combination of the FCA with the WDFE.

This paper provides a theoretical characterization of the multihop wireless communications channel with diversity, wherein intermediate terminals relay information employing spatial diversity techniques. Two channel models are proposed and developed: one where each intermediate terminal combines, digitally decodes, and re-encodes the received signals from all preceding terminals and the other where each intermediate terminal simply combines and amplifies the received signals from all preceding terminals. These models are compared, through analysis and simulations, with the single-hop reference channel on the basis of probability of outage and probability of error. Both models achieve significant gains over the single-hop reference channel, with the amplified relaying model outperforming the decoded relaying model despite noise propagation.

The Local Multipoint Communication Services (LMCS) refer to millimeter-wave point-to-multipoint access systems that provide broadband services to both residential and commercial subscribers. Coverage is the most important problem to be resolved for the successful deployment of the LMCS systems. This paper reports the performance study of LMCS in relation to transmit power control. An extensive simulation model has been used to study the effects of a number of factors on the system outage performance. These factors include the propagation model, power control command rate, step size and dynamic range.

Introduction Disadvantaged men suffer substantial harm from heavy drinking. Effective brief interventions to reduce alcohol consumption have been developed for middle-aged men. These were mainly delivered in healthcare settings. Disadvantaged young men seldom attend healthcare. A tailored brief intervention delivered by text message provides a low cost method for accessing this hard to reach group. Methods Focus groups were conducted with disadvantaged young men to explore the social context of drinking and opportunities for intervention. Empirical evidence and social cognition theories were used to develop a series of text messages and images to reduce binge drinking. These were tested in three further focus groups, including one with female partners of binge drinkers. Results The focus groups identified cost and personal experience of alcohol harms as opportunities for intervention. Humour was identified as a useful lever for behaviour change. The focus groups also provided useful quotes for text messages. A series of 37 text messages and images were developed within the framework of the Stages of Change model. They incorporated the principles of motivational interviewing and used components of successful behaviour change strategies. To promote interaction, several messages requested a response. Conclusion This study has shown it is possible to encapsulate the theoretical approaches and the major components of brief interventions in a series of text messages. Focus groups highlighted levers for change and aided the selection of acceptable messages. This approach could be used with other social groups and other adverse health behaviours.

Total protein, mucin, and specific nonmucin glycoproteins are proposed pronucleating agents in cholesterol gallstone pathogenesis. However, characterization of specific nonmucin glycoproteins in patients with and without gallstones is unknown. Furthermore, nonmucin glycoproteins may be qualitatively different in patients with and without gallstones. Total protein and total and specific nonmucin glycoproteins were studied in gallbladder bile of 43 patients with cholesterol gallstones and 13 patients without gallstones. Patients with cholesterol gallstones had higher concentrations of both total protein and nonmucin glycoproteins than that observed in control patients (P0.05). SDS gel electrophoresis of nonmucin glycoproteins demonstrated an 84-kDa protein that was present significantly more often in patients with cholesterol gallstones (87% vs 8%, P0.05). Proposed 130- and 42-kDa pronucleating and 120-kDa anti-nucleating nonmucin glycoproteins were present in similar percentages in gallstone and control bile. Moreover, gallbladder bile of patients with the 84-kDa protein nucleated 50% faster than model bile and100% faster than that of patients without this protein (P0.05). The currently described gallbladder pronucleating and anti-nucleating proteins are found with equal frequency in cholesterol gallstone and control patients. However, an 84-kDa protein is found more commonly in gallstone patients and was associated with a shortened crystal observation time. Thus, this glycoprotein may be important in cholesterol gallstone pathogenesis.

While still rare, cancer has the reputation of being life-threatening in all its forms. Coupled with the survival of cancer comes a growing expectation from the patients that their life should be relatively unaffected. Among the side effects, there is frequently an effect on fertility. In particular, the treatment of the young with anti-cancer therapy raises questions about the patient's ability to achieve normal reproductive function and delivery following treatment. Between 1987 and 1998 we identified 40 women who conceived or delivered a fetus following treatment for cancer. They had undergone a combination of therapies including surgery, chemotherapy and radiotherapy. Four had elected to be sterilised after completion of their family. It did not appear from the data collected that the therapy used for treatment of some cancers has had an adverse effect on delivery outcomes, expected weight of the fetus or the gestation of the pregnancy.

A maximum-likelihood channel estimator for the orthogonal frequency division multiplexing communication environments, in the presence of interference is discussed here. In a training-based scenario, the channel is estimated based on pilots that precede the transmission of the information. To reduce the number of estimation parameters, the channel is estimated iteratively in time-domain. Since interference from other users provide no useful information, parameters of the interference are neither estimated nor the effect of the interference neglected, instead interference along with Gaussian noise is perceived as non-Gaussian noise process. The algorithm assumes no a priori knowledge about the interfering channel and signal at the receiver, further no assumption on the statistical properties of the interferer is assumed, which makes this algorithm robust. The estimated channel information along with the estimated distribution are then utilised to equalise the subsequent data blocks. The strength of the algorithm is in its robustness to both synchronous and asynchronous interference, which is confirmed by the simulation results for both flat and multipath fading channels in presence of synchronous and asynchronous interference.

A convergence analysis of a jointly adaptive transversal and memory-based or nonlinear echo canceller is presented. The coefficients of the transversal echo canceller (TEC) and the memory echo canceller (MEC) are updated simultaneously using the well-known least mean square (LMS) algorithm with separate adaptation constants and a common cancellation error. The amount of linear echo cancellation load-sharing between the TEC and MEC is shown to be governed by a fixed relationship that exists between the MEC coefficients and those TEC coefficients updated using the shared portion of the input symbol span. The average mean square error is derived for the case of binary input symbols and compared to that of an identical canceller adopting a sequential adaptation method where the TEC coefficients are adapted first and permitted to converge before MEC coefficient adaptation is initiated for jointly adaptive operation. Bounds for both adaptation constants are found for MSE convergence for the jointly adaptive case. The adaptation constants that yield the fastest jointly adaptive convergence are also derived. The sequential method is shown to have an overall convergence rate advantage that decreases as the ratio of the number of TEC coefficients to MEC coefficients becomes large. The theoretical results are supported by computer simulations.

Asymptotically optimum (in the sense of minimum per-symbol error rate) receiver structures for data communication over the white Gaussian channel with unknown time delay and carrier phase jitter are developed. The receiver structures apply to the following suppressed-carrier modulation systems: double sideband (DSB), quadrature amplitude modulation (QAM) with an arbitrary constellation, vestigial sideband (VSB) and single sideband. The resulting minimum error probability receivers are asymptotically equivalent to maximum-likelihood digital {\em sequence}-estimating receivers. The optimum structures implicitly derive joint maximum-likelihood estimates of the unknown parameters and of the sequence of data symbols. It is shown that the parameter estimates can be obtained from two data-directed stochastic approximation algorithms. Unlike traditional theoretical treatments of this communication situation, which have separated the highly important carrier phase and timing recovery problem from the detection problem, a unified theory is presented from which the complete ideal receiver structure can be deduced.

Decision feedback equalization is presently of interest as a technique for reducing intersymbol interference in high-rate PAM data communications systems. The basic principle is to cancel out intersymbol interference arising from previously decided data symbols at the receiver, leaving remaining intersymbol interference components to be handled by linear equalization. In this work we consider the application of decision feedback equalization to quadrature-amplitude modulation (QAM) transmission, in which two independent information streams modulate quadrature carriers. Extending Salz's treatment in a companion paper of decision feedback for a baseband channel, we derive the form of the optimum receiver filters via a matrix Wiener-Hopf analysis. We obtain explicit analytical expressions for minimum mean-square error and optimum transmitting filters. The optimization is subject to a constraint on the transmitted signal power and assumes no prior decision errors. The class of QAM transmitter and receiver structures treated here is actually much larger than the class usually considered for QAM systems. However, our results for decision feedback equalization show that, for nonexcess bandwidth systems, optimum performance is achievable without taking advantage of the most general structure. If the transmitter is required to have the conventional QAM structure, study of the time continuous system that gives rise to the sampled data system considered here demonstrates that under quite general assumptions a nonexcess bandwidth system is optimum. Finally, the explicit description of the optimum transmitting matrix filter follows from an information-theoretic “water-pouring” algorithm in conjunction with the determination of the form of the points of maxima of a determinant extremal problem.

Protection switching of digital radio channels results in a timing-phase discontinuity and occasional long error bursts in the demodulated data signal. Using an idealized mathematical model, we derive maximum likelihood receivers which rapidly track such delay hits, whether or not a timing-pilot tone is used. When the receiver is at a different physical location from the switch, the tracking algorithm must also sense the occurrence of a switch. A dual-mode, data-directed structure is revealed as being optimum; a narrowband tracking loop is used for steady-state operation, while a wideband tracking loop provides rapid recovery from the timing transient. An error-sensing nonlinearity, which incorporates hysteresis, inhibits erroneous noise-induced mode transitions. Oversampling of the demodulated data signal rapidly establishes a coarsely quantized, optimum sampling phase and permits the dual-mode tracking loop to operate in a data-directed manner. Data-directed operation permits greater loop bandwidths, since the data energy is not perceived as noise. Simulation of a digital data transmission system employing a dual-mode, data-directed, and coarse-quantized timing loop has demonstrated dramatic reduction in the length of error bursts following a protection switch. For example, at the data rate of 1.544 Mb/s, a conventional phase-locked loop with a 100-Hz bandwidth, when displaced a half-symbol interval by a delay hit, would typically sustain an error burst 15,000 bits in duration. When such a delay hit stresses the dual-mode timing loop, simulation has indicated error bursts on the order of 15 bits in duration.

In this paper, we describe a novel receiver structure for two-dimensional-modulated, suppressed-carrier data signals. The receiver consists of a passband equalizer followed by a demodulator which compensates for frequency offset and phase jitter; the demodulator's phase angle is provided by a data-directed, carrier recovery loop, which is shown by analysis and simulation to be capable of tracking relatively high frequency phase jitter. A derivation of the receiver parameters is presented, based on a gradient algorithm for jointly optimizing the equalizer tap coefficients and the carrier phase estimate, to minimize the output mean-squared error. System performance is related to carrier phase-tracking parameters by analysis. Computer simulations confirm the feasibility of the receiver structure.

We describe and experimentally evaluate a receiver structure for two-dimensional data communication systems based on passband decision feedback equalization and data-directed carrier recovery. The forward and feedback tap coefficients and the demodulator's carrier phase angle are adjusted adaptively; the carrier recovery and demodulation operation, as in the case of a linear equalization receiver, can compensate for rather severe frequency offset and phase jitter. Experimental results are reported of simulations of the receiver on voiceband telephone channels.

Three different receiver arrangements are studied, all of which incorporate provision for joint adaptive echo cancellation and gain adjustment to provide two-wire full-duplex data communication. In each case, the canceler consists of a data-driven transversal filter, but the architectures differ in the way the gain adjustment is provided. For all architectures, we investigate the properties of a joint adaptive lms algorithm based on the receiver's decisions on far-end data symbols and present appropriate computer simulations. We show that an arrangement where the gain control adjusts the reference level after the decision detector output performs significantly better than agc schemes attempting to adjust the level of the analog signal.

Data transmission at rates of 1.2 kbits/s or higher through voiceband ionospheric channels is subject to impairment from severe linear distortion, fast channel time variations, and severe fading. In this paper, we have focused on the performance of DFE (decision feedback equalization) receivers for communication over 3 kHz bandwidth HF channels. We describe the results of simulations for a wide range of fading rates on simulated and real recorded HF channels, using fractionally spaced DFE receivers. Both LMS (least mean square) and FRLS (fast recursive least squares) adaptation algorithms with periodic restart were evaluated, and both ideal-reference and decision-directed operation was observed. The results indicate that FRLS adaptation yields superior performance to LMS in rapid fading conditions, but that this performance advantage diminishes at low signal-to-noise ratios. Also, fade rates greater than about 1 Hz produced relatively high error rates, irrespective of which adaptation method was employed. Finally, a novel modification of the simple LMS algorithm which improves its tracking ability was evaluated. This involved preceding the LMS DFE receiver with an adaptive lattice whitening filter.

Semipurified diets produce a marked hypercholesterolemia in rabbits and tend to elevate the level of plasma cholesterol in rats. They also decrease rates of oxidation of [26-14C]cholesterol to respiratory 14CO2 and excretion of label in fecal lipid, compared with commercial feed. In both species, the hypercholesterolemia was prevented and the rate of oxidation of [26-14C]-cholesterol increased by using unmodified potato starch as the carbohydrate component of the semipurified diets. Potato starch was poorly digested by rats but appeared to be well utilized by rabbits. A semipurified diet containing cooked potato starch gave results in rats comparable to those obtained with diets containing other types of carbohydrate. Cooked potato starch produced diarrhea in rabbits, thus complicating interpretation of the results. When the diarrhea was treated with antibiotics, the results were similar to those obtained with other carbohydrates. Rats fed commercial diet which had been heated in an oven or autoclaved had higher plasma levels than those fed untreated commercial diet but no significant differences in rates of oxidation or excretion of cholesterol were observed.

Within the population of voiceband telephone channels, few channel characteristics are as pervasive in their impairment of high-speed data communication as nonlinear distortion, which cannot be removed or equalized in the receiver as easily as can linear distortion. The purpose of this paper is to report on an investigation of a QAM receiver incorporating adaptive equalization of nonlinearities as well as adaptive decision feedback equalization and data-aided carrier recovery for mitigation of linear distortion and phase jitter, respectively. Nonlinearities are equalized by adding to the received in-phase and quadrature signals a weighted sum of nonlinear functionals of the received signal and of modulated previous receiver decisions. The choice of nonlinear terms in the sum is based on a channel model incorporating quadratic and cubic nonlinearities as well as linear dispersive elements. The adjustment of the weighting, or tap, coefficients for the various terms is based on a gradient algorithm, as is the adjustment of the linear tap coefficients and the carrier phase reference. The feasibility of nonlinearity equalization on real voiceband channels was confirmed in a test in which recorded 9600-bps QAM signals, received from a worse-than-average set of 17 voiceband telephone channels, were processed by a computer-simulated version of the proposed receiver (termed the NL receiver). The observed error rates for all channels were lower, in some cases by several orders of magnitude, than those achieved by computer-simulated versions of the linear receiver and of a decision feedback equalization receiver (termed the DFE receiver).

Summary. Blood gases and plasma catecholamines were measured in umbilical arterial and venous blood samples after delivery. In all cases umbilical arterial noradrenaline concentrations were higher than venous levels. The lowest concentrations of noradrenaline were found after elective cacsarean section. Vaginal delivery, particularly when accompanied by instrumental manipulation, was associated with significantly higher concentrations of arterial noradrenaline. High concentrations of catecholamines were commonly recorded in those deliveries showing evidence of acid-base disturbance. Noradrenaline was the predominant catecholamine in all cases. A linear relation was demonstrated between arterial noradrenaline and arteriovenous noradrenaline difference.

This paper describes experimental results of simulated 12000 and 14400 bits/s quadrature amplitude-modulated (QAM) systems (which were described in detail in Part I [1] ) operating on real and simulated voiceband channels. These experimental results show that both Viterbi algorithm detection and decision feedback equalization allow digital data transmission at symbol rates exceeding the nominal bandwidth capabilities of typical telephone channels. It is demonstrated in these experiments that the Viterbi algorithm receiver structure tested is less affected by linear distortion than the decision feedback receiver but exhibits greater sensitivity to phase jitter. On conditioned voiceband channels where there may be substantial phase jitter, a reasonable compromise between sensitivity to distortion and noise and sensitivity to phase jitter is made by a modem employing decision feedback equalization and decision-directed carrier phase tracking.

A two-dimensional receiver structure has been proposed, incorporating two innovations: passband equalization, which mitigates intersymbol interference, and data-directed carrier recovery and demodulation following equalization, which enables compensation of carrier frequency offset and phase jitter, but does not require transmission of a separate pilot tone with the data signal. The receiver is fully adaptive; the adjustment of the equalizer tap coefficients and of the estimate of the current channel phase shift is based on a gradient algorithm for jointly minimizing the mean squared error with respect to those parameters. In this paper, we analyze the dynamic behavior of the deterministic gradient algorithm (where channel parameters entering into the gradient expression are assumed known in advance). The corresponding estimated gradient algorithm (where these parameters are initially unknown) has previously been studied experimentally, but is not treated here. The first part of the present study concerns system start-up (or transient) response when the channel's phase shift is fixed. Examination of the analytical solution leads to the qualitative conclusion that, if the equalizer tap adaptation coefficient β is small relative to the phase-tracking coefficient α, the added phase estimation feature does not strongly affect the start-up behavior of the passband equalizer under typical operating conditions. Indeed, if the equalizer tap coefficients all start at zero, their evolution in the deterministic gradient algorithm is completely unaffected by the phase-tracking loop. The second situation analyzed is the steady-state response of the system to a constant carrier frequency offset. In this case, the phase-tracking loop is found to reduce the resulting rate of rotation of the equalizer taps to about β/(α + β) of the original frequency offset. As a result, the degradation in system mean squared error due to frequency offset is typically quite small. The final analysis is of the response of a linearized version of the receiver structure to sinusoidal phase jitter. When the channel's linear

Summary. Plasma cortisol and noradrenaline were measured in 15 mothers and babies following vaginal delivery and in 17 following elective caesarean section and related to blood concentration of glucose and glycerol. Significant elevations in umbilical artery cortisol and noradrenaline concentration were found in the vaginal delivery group. Blood glucose and glycerol concentrations were significantly higher in the vaginal delivery group for maternal venous, umbilical artery and vein samples. However, when allowances were made for placental transfer of these substances, little evidence was found to support sympatho-adrenal mediated mobilization of glycerol and glucose in the fetus. The possible explanation for the apparent dissociation between marked sympatho-adrenal activity and metabolic responsiveness during parturition in the fetus is discussed.

The performance of a pole-zero adaptive filter in echo cancellation is studied. Compared with conventional transversal filters, this structure requires fewer taps to achieve the same echo cancellation performance when the echo path can be well modeled by a rational transfer function. Such issues as the degree of echo cancellation, the stability of the filter, the selection of the order, and the effects of observation noise are studied by using simulated echo path models and then tested with actual measured acoustic echo models in teleconferencing. The advantages and remaining problems are discussed.

This paper presents data on the ozone mixing ratio, static air temperature, wind speed, and wind direction obtained at altitudes from 8 to 12 km during several flights of a commercial airliner equipped with a fully automated air-sampling system developed for the NASA Global Atmospheric Sampling Program (GASP). The objectives of GASP are reviewed, and the data-gathering techniques are described. Two data sets are discussed which illustrate variations of the upper-tropospheric and lower-stratospheric ozone mixing ratios as a function of geographical location and aircraft altitude. Good agreement is found between the GASP data and the tropopause height obtained from National Meteorological Center gridded data.

A ground-based, cloud water collection system capable of intercepting significant volumes of water from clouds has been in operation at a mountain field station in the Adirondack Mountains of New York State for three summer seasons. An analysis of cloud water pH for August–September 1977 and 1979 strongly suggests that acid input to the ecosystem due to clouds at Whiteface Mountain may be significantly more important than that due to the much-discussed phenomenon of acid precipitation. The mean pH of nonprecipitating clouds was 3.55 during 1977 and 3.50 during 1979; approximately 90% of all observations were found in the pH interval between 2.66 and 4.66. In the event that precipitation is intercepted concurrently with cloud droplets, a minimum dilution of the cloud water acidity by a factor of 60–80% can be expected. Other aspects of the collection and pH analysis of cloud water at Whiteface Mountain are also discussed.

At the University of Nottingham, students are taught aspects of reproductive biology throughout the Part I Basic Medical Science Course. Teachers from the Departments of Physiology and Pharmacology, Human Morphology, Biochemistry, Obstetrics and Gynaecology, and Psychiatry are involved, and an obstetrician in training (the author) has been appointed full-time lecturer in Physiology and Pharmacology to provide an additional link between the basic science and clinical content of the course. The Part II course includes an Honours Year, to give students an opportunity to explore further the application of scientific method in clinical practice. One project, in which students were involved in physiological measurement used in current obstetric practice, is described here. In addition to carrying out practical tasks, students were required to submit written reports and to prepare a learning resource on fetal acid-base balance for use by their junior colleagues. Supervision was provided by obstetric and paediatric registrars and senior house officers, and senior midwives, while staff in the Department of Physiology and Pharmacology assisted students with data analysis. Each project task was assessed by a supervisor and an independent observer. The project proved acceptable to students, supervisors and hospital staff, and avoided interfering with the other responsibilities of a busy obstetric unit. It is intended to repeat the exercise with minor modifications.

Archived radar reports, derived from the National Weather Service radar network, were used to estimate the average annual frequencies of thunderstorm days across New York State for the period 1978–81. The archival records consist of manually-digitized radar (MDR) data, available on magnetic tapes and arranged as hourly, digitally-encoded radar reflectivity values within a high-resolution grid of reporting blocks, each 45 × 45 km. Analyses of these data made use of an experimentally-derived relationship between radar reflectivities and the presence and intensities of thunderstorms. The radar-based thunderstorm day climatology generally agreed to within 15% of conventional, surface-based thunderstorm day statistics reported for the same period by National Weather Service (NWS) offices located within range of two or more network radars in the State. Poorest agreement between annual totals was found at selected NWS offices in the Greater New York City Metropolitan Area and northward into the lower Hu...

Adaptive signal processing algorithms derived from LS (least squares) cost functions are known to converge extremely fast and have excellent capabilities to "track" an unknown parameter vector. This paper treats analytically and experimentally the steady-state operation of RLS (recursive least squares) adaptive filters with exponential windows for stationary and nonstationary inputs. A new formula for the "estimation-noise" has been derived involving second- and fourth-order statistics of the filter input as well as the exponential windowing factor and filter length. Furthermore, it is shown that the adaptation process associated with "lag effects" depends solely on the exponential weighting parameter λ. In addition, the calculation of the excess mean square error due to the lag for an assumed Markov channel provides the necessary information about tradeoffs between speed of adaptation and steady-state error. It is also the basis for comparison to the simple LMS algorithm, in a simple case of channel identification, it is shown that the LMS and RLS adaptive filters have the same tracking behavior. Finally, in the last part, we present new RLS restart procedures applied to transversal structures for mitigating the disastrous results of the third source of noise, namely, finite precision arithmetic.

Approximate expressions quantifying performance expectations for LMS adaptive echo cancellers using single-bit correlation multipliers are derived. Linear coefficient coding is assumed at first. The analysis is then extended to quantify the potential improvements obtainable through the use of companded coefficient coding schemes and the addition of simple midtread quantizing features. All derivations are supported by results generated via a computer simulation. Work in this area can lead to the design of sampled analog echo cancellers which require no A/D converters.

Subjective quality measurements on three digital speech coders, simulated with mobile radio channel transmission, were performed using the "mean opinion score (MOS)" method. The three speech coding methods tested were: continuously variable slope deltamodulation (CVSD) coding, adaptive predictive coding (APC), and residually excited linear predictive (RELP) coding. Several versions of each coder, with transmission rates in the range of 7.3 to 16.1 kbits/s, were simulated. Five different channel conditions, including three derived from land mobile radio field experiments, were applied to the speech coders' encoded output to study the effects. The results show that of the three coders, the CVSD coder is the most robust to channel errors, but produces reconstructed output speech of unacceptable quality. The 14.4 kbit/s RELP coder produces relatively good Output speech quality, exhibits a mild degree of robustness to mobile radio channel errors, and is slightly less complex than the APC coder. Of the three digital speech coders tested, the RELP coder appears the most suitable for use with land mobile radio. However none of the three coders was able to produce speech of telephone toll quality in a mobile radio environment.

A computer model for determining the disposition by latitude and height of short- and longwave radiation fluxes is developed. The atmosphere has been partitioned into twenty equal pressure layers from 1013 mb to 0 mb. Model inputs, which are either known or assumed, include the zonally averaged, vertical profiles of temperature, specific humidity, aerosol concentration, and cluod cover as well as ozone, carbon dioxide content, surface albedo, and solar zenith angle. All atmospheric scattering and absorption processes are then treated explicitly. The outputs are the individual components of the short- and longwave energy fluxes. Results for January, April, July, and October are presented. Graphs of the resultant surface global radiation, planetary albedo, as well as vertical profiles of the net radiative balances are discussed.

An upper bound is obtained on the probability that a specified pattern of errors, caused by a combination of intersymbol interference and additive Gaussian noise, occurs in an amplitudemodulated digital data transmission system. The bound, which is a generalization of Saltzberg's upper bound for the probability of a single error, behaves as an exponential function of the signal-to-noise ratio and the overall channel impulse response. The exponent of the bound for a pair of errors is calculated for two "typical" channels and in each case is fairly close to twice the corresponding Saltzberg exponent for a single error.

The Bathgate and Linlithgow Hills occupy a well-defined belt of rising ground stretching S.S.W.–N.N.E. from Bathgate to Bo'ness, and included in the marginal portions of sheets 31 and 32 of the 1-in. maps of the Ordnance and Geological Surveys. Throughout the range the steeper slopes face the west, while the eastern flanks are deeply buried in drift. The glaciated contours are well seen from the east, and the sky-line is in several places deeply indented by glacial grooves. The physical geography is throughout intimately dependent upon the geological structure, but the latter is simplicity itself when contrasted with the complicated structure of the shale-fields to the east. Alternating zones of volcanic and sedimentary rocks strike parallel with the direction of elongation of the range from Bathgate to Bonnytoun Hill, and these are cut by a later connected series of dykes and sills of intrusive igneous rock. The latter, as a rule, are more resistant than the lavas, and form the more prominent features of the landscape, while the sedimentary intercalations may frequently be traced, even where no rock is visible, by the trough-like depressions which have been hollowed out of them between the zones of lava.