Simulation of phase nonlinearity effects in a satellite channel

There are different interferences in the satellite communication. A example is given in the paper, it is shown from the simulation that when using smart antenna and PASTd algorithm in the satellite communication, the radiation patterns formed by smart antenna points a main beam in the direction of the desired signal but the ability to cancel inferences.

The paper studies a digital modem that transmits a convolutionally encoded eight‐phase‐shift keyed (CE8PSK) signal over a satellite channel and employs a near‐maximum‐likelihood decoder at the receiver. Several different earth‐stations are assumed to have simultaneous access to a given transponder in the satellite as an arrangement of frequency‐division multiple access. Adjacent channel interference (ACI) is neglected here. The high‐power amplifier (HPA) at the earth‐station transmitter and the satellite transponder are assumed to be linear. The channel distorts the data signal, through the bandlimiting introduced by the equipment filters, and it adds stationary white Gaussian noise to the data signal at the receiver input. The resulting noisy and distorted data signal is coherently demodulated. Four different bandwidths of the transmitted CE8PSK signal are considered, together with three different demodulation processes. The decoder uses the Viterbi algorithm, together with one of six different distance measures to determine the costs of the stored vectors (survivors).The paper describes the various techniques involved in the modem, and presents the results of an extensive series of computer‐simulation tests to measure the performances of the system with all appropriate combinations of the signal bandwidth, demodulation process and distance measure. The results of the tests are then used to determine the preferred modem design.

Low Earth Orbits (LEO) satellites are used for public communication and for scientific purposes. These satellites provide opportunities for investigations for which alternative techniques are either difficult or impossible to apply. Ground stations have to be established in order to communicate with such satellites. Usually these satellites communicate with ground stations at S-band. The communication quality depends on the performance of the satellite ground station, in addition to that of satellite. The performance of the satellite ground stations is expressed through Figure of Merit. The aim of this paper is to analyze the rain attenuation impact on the performance of the respective ground station. Rain attenuation depends on geographical location where the satellite ground station is implemented. In order to compare this effect on satellite ground station performance, some cities of Europe are considered. Finally, the rain attenuation impact on the satellite ground station Figure of Merit for the hypothetical satellite ground station installed in Prishtina is analyzed.

This study introduces the group delay and its characteristics in satellite channel, meanwhile, the model of the impact of group delay ripple on performance of direct sequence spread spectrum communication system is established and simulated for analysis. The simulation results indicate the specific impact of group delay ripple on system, as well as the impact of group delay ripple on the transmission and reception signals in the spread spectrum communication system. For transmission signals in the spread spectrum system, the group delay ripple can worsen the EVM and Eye-diagram of spread spectrum signal, cause signal distortion and the deterioration of noise tolerance. For the reception performance of the spread spectrum system, the group delay ripple has little effect on the spread spectrum acquisition using incoherent accumulation and energy judgment, but it can cause a deterioration in the error performance of the reception signal. For example, when relative group delay increases from 0.011 to 0.9, the error performance decreases by about 2 dB. When designing satellite spread spectrum communication systems, power resources are extremely precious, it is necessary to consider the impact of group delay on the communication system, and take certain measures to reduce the impact of group delay ripple to the system.

In this work, design of a five-element compact dual-polarization X band monopulse feed antenna using a 7.3 m Cassegrain-type reflector for Low Earth Orbit (LEO) satellite ground station is presented. The designed antenna has reached 32 dB/K G/T value, the side lobe level of the designed antenna is at the level of −24 dB, the crosspolarization value is −35 dB, and the port isolation value is below −29 dB in the 8–8.5 GHz frequency range. The antenna efficiency of the designed antenna is measured as 79.93%.

Energy detector is the simplest spectrum sensing technique in cognitive radio in terms of computation complexity as it is developed assuming only channel noises for the detection of primary user signal. However in realistic sense the typical communication system comprises of various other sources of noise (like thermal noise) that significantly affect the sensing performance of the detector. The conventional energy detector is also not a coherent detector as the attributes of the primary user signal is unknown. Considering these limitations a system is proposed that can have the knowledge of the primary user signal attributes under realistic situation at the secondary user (SU) receiver thereby enhancing the accuracy of the sensing significantly. In this work a new coherent energy detector system architecture is proposed that first separates the signal components from a noisy signals (non Gaussian noise) at SU receiver, then from the separated signals it estimates the signal attributes (power of the signal, noise variance, signal-to-noise ratio) required for conventional energy detector. The work is developed as a hybrid system model utilizing blind source separation algorithm and neural network (NN) known hereafter as ‘integrated blind signal separation (BSS)-NN based energy detector’.

Neural network-based techniques for efficient detection of variable-bit-rate signals in MC-CDMA systems working over LEO satellite networks

Simulation of stochastic loads for fatigue experiments

We use theoretical models to compare the receiver signal to noise ratio (SNR) vs. average rate of detected signal photons for an integrated path differential absorption (IPDA) lidar using coherent detection with continuous wave (CW) lasers and direct detection with sine-wave and pulse modulations. The results show the coherent IPDA lidar has high receiver gain and narrow bandwidth to overcome the effects of detector circuit noise and background light, but the actual receiver performance can be limited by the coherent mixing efficiency, speckle and other factors. For direct detection, using sine-wave modulation allows the use of a low peak power laser transmitter and synchronous detection. The pulse modulation technique requires higher laser peak powers but is more efficient than sine-wave modulation in terms of average detected signal photon rate required to achieve a given receiver SNR. We also conducted experiments for the direct detection cases and the results agreed well with theory.

This chapter considers the bit error rate performance of digital signaling on frequency non-selective (flat) fading channels with additive white Gaussian noise AWGN. A vector representation is first introduced for digital signaling on flat fading channels with additive white Gaussian noise (AWGN). Afterwards, a generalized analysis is provided for the error rate performance of digital signaling on flat fading channels. The structure of the optimum coherent receiver is then derived for the detection of known signals in AWGN. The error probability performance of various coherently detected digital signaling schemes is considered, including phase shift keying, quadrature amplitude shift keying, orthogonal signals, and orthogonal frequency division multiplexing. Other types of detection schemes are treated, including differential detection of differentially encoded binary phase shift keying and differentially encoded π∕4-phase shifted quadrature phase shift keying. Also considered is the non-coherent detection of orthogonal signals. Finally, the chapter wraps up with a treatment of coherent and non-coherent detection of continuous phase modulated signals.

This paper aims to investigate the effect of nonlinear satellite channels as well as multipath fading and CCI on the performance of a MIMO-beamforming system. Simulation results confirm the decrease in system performance when both nonlinearity and mutipath fading are taken into account.

الهدف من الدراسة: معرفة تأثير التليفزيوني بالقنوات الفضائية العربية على السلوک الاستهلاکي للشباب الجامعي . نوع الدراسة والمنهج المستخدم: تندرج هذه الدراسة تحت نوع البحوث الوصفية، وقد استخدم الباحث منهج المسح التحليلي الذي يعتمد علي دراسة الظاهرة کما توجد في الواقع. عينة الدراسة وأدوات جمع البيانات: طبقت الدراسة على عينة عشوائية قوامها 400 مفردة من الطلاب والطالبات بجامعتي : الأزهر ، القاهرة ، وقد کان اختيار العينة ممثلا للذکور والإناث، وللکليات العملية والنظرية ، والمستويات العمرية والاجتماعية والاقتصادية، واختار الباحث (الاستبيان) کأداة لجمع بيانات ومعلومات هذه الدراسة أهم ما توصلت إليه الدراسة: - أقوي تأثير للإعلان علي قرار شراء السلع والخدمات، کان لان الإعلان يبين جودة المنتجات وکفائتها ثم أن (الإعلان يعمل على إثارة الحاجة للسلع الغذائية والمشروبات والأطعمة المختلفة). - أضعف تأثير للإعلان على قرار شراء السلع والخدمات کان (أسعار السلع والخدمات المعلن عنها مناسبة ومعقولة ) - غالبية أفراد العينة أکدوا على أن الإعلانات التي تقدمها القنوات الفضائية هي إقوى دافع لاقتنائهم السلع والخدمات ، ثم الإعلانات والدعايات التجارية من الدوافع المؤثرة في اقتنائهم للسلع والخدمات. - أن نسبة المشاهدين الذين يدفعهم إلى الرغبة في اقتناء السلع والخدمات التي يحتاجون لها بلغت نسبتهم لدائما 62.1 %. Title: The Effect of Arab TV Channels on the Consumer Behavior of University Youth. Researcher Name: Dr. Mahmoud Abdel-Ati Muslim, Assistant Professor, Faculty of Mass Communication, Al-Azhar University The objective of the study: to investigate the effect of television on Arab satellite channels on the consumption behavior of university youth. Type of study and methodology used: This study falls under the type of descriptive research. Study sample and data collection tools: The study was applied to a random sample of 400 male and female students in Al-Azhar and Cairo universities. studying The most important findings of the study: 1-The strongest impact of the Declaration on the decision to buy goods and services, was because advertising shows the quality and efficiency of products and then that (advertising works to raise the need for food commodities, beverages and various foods). 2-The weakest effect of on the decision to buy goods and services was (prices of goods and services advertised are reasonable and reasonable) 3-The majority of respondents emphasized that the advertisements provided by satellite channels are the most powerful motivation for their acquisition of goods and services, then commercials and advertisements are one of the motivations that affect their acquisition of goods and services. 4-The percentage of viewers who are motivated by the advertisement to desire to acquire the goods and services they need is always 62.1%.

The capture phenomenon and its consequences in nonbitsynchronous mobile packet radio networks for binary phase-shift-keying (BPSK) and differential phase-shift-keying modulation are investigated. Exact values of the bit error probability for given signal-to-noise ratios of colliding BPSK signals are derived. Packet error rates, which are needed for analysis of slotted random multiple access methods, are obtained by simulation. Two kinds of mobile radio channels are considered: the Rayleigh fading channel and the land mobile satellite channel. In the latter, because of shadowing, the probability that one of several colliding data packets is correctly received can be on the same order as the probability that a single packet that is not experiencing a collision is correctly received. The influence of Reed-Solomon codes on packet error probabilities is also studied. A slotted ALOHA system using the land mobile satellite channel is analyzed. It is found that with significant shadowing, the overall system throughput may reach the point-to-point throughput. Also, the code rate cannot be optimized in a straightforward manner by assuming one single transmission at a time.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Redefining Auditory Processing Disorder: A Speech-Language Pathologist’s Perspective

The problem of optimal signal design for coherent detection of binary signals in Gaussian noise is revisited under power and secrecy constraints. In particular, the aim is to select the binary transmitted signals in an optimal manner so that the probability of error is minimized at an intended receiver while the probability of error at an eavesdropper is maintained above a threshold value and the signal powers are limited. It is shown that an optimal solution exists in the form of antipodal signaling along the eigenvector corresponding to the solution of a maximum (possibly generalized) eigenvalue problem, which is specified explicitly based on the channel coefficient matrices and the noise covariance matrices at the intended receiver and the eavesdropper. Furthermore, optimal signal design can be performed in an efficient manner by solving a semidefinite programming (SDP) relaxation followed by a matrix rank-one decomposition. Numerical examples are provided to illustrate optimal solutions for three different but exhaustive cases.