Simplex Communication Research Articles

Integrated superregenerative amplifier based 24 GHz frequency modulated continuous wave radar active reflector tags for joint ranging and communication

AbstractConcepts for two cooperative active reflector tags (ARTs) for joint ranging and communication in a linear frequency modulated continuous wave secondary radar system are presented along with corresponding theoretical derivations. To prove the concepts, the ARTs operating from 24 to 24.5 GHz are implemented using custom integrated superregenerative amplifiers (SRAs) designed in a 130 nm SiGe BiCMOS technology. The SRAs have a measured minimum detected input power greater than −80 dBm, and an output power greater than 3.2 dBm after wire‐bonding. The ARTs also feature roll invariance using bandwidth enhanced microstrip patch antenna diversity and a novel quench frequency shift keying based low data rate simplex communication. Indoor ranging experiments done to prove the concepts and the theoretical considerations show a maximum distance of 77 m in the ranging mode and a data rate of 0.5 symbols per second in the data transfer mode. For distances less than 5 m, the characterised accuracy is better than 12 cm and the precision is better than 2 cm. To the best of authors' knowledge this is one of the first reported scientific works leading to a proof of concept for integrated superregenerative amplifier based joint ranging and quench frequency shift keying. The combination of maximum range and precision are also one of the best reported among similar works in the literature.

Acoustic communication through well-head for an untethered autonomous well logging tool

Untethered autonomous well logging tools have recently been introduced to oilfields. Once deployed into a well, the tools autonomously travel in the well to collect data and return to surface after the mission is completed. A service operator needs to travel to the well-site and open the well cap to check if the tool has returned. This increases the operational time and cost. This can be addressed by implementing a return detector and notifying the operator. Steel well-head construction leaves acoustics as the most viable option for such detection. We demonstrated a proof of concept of acoustic based simplex communication system through well-head. A pair of identical transducers were used as transmitter and receiver that operates at 155 kHz. Transmitter piezo was positioned at the center of a water filled steel wellhead with 7-inch diameter and 0.25-in. wall thickness, while the receiver was taped outside the wellhead with grease to increase acoustic coupling. Transmission loss was measured as -57 dB which was partially compensated by using a receiver amplifier stage with a gain of 1000. Next, the transmitter will be incorporated on a miniaturized untethered well logging tool.

Estimation and representation of regional atmospheric corrections for augmenting real-time single-frequency PPP

Real-time single-frequency precise point positioning (PPP) can be significantly augmented by applying high-quality atmospheric corrections. In previous work, the satellite-and-station-specific slant total electron content (STEC) ionospheric corrections, derived from a regional reference network, are commonly used to augment single-frequency PPP for improving positioning accuracy and faster convergence. However, since the users are required to interpolate STEC ionospheric corrections from nearby reference stations, either duplex communication links should be established or all corrections of the reference network must be retrieved, which makes it inefficient to provide augmentation services to many users. Moreover, the regional tropospheric corrections are generally neglected in augmenting real-time single-frequency PPP. In this study, we present a method to estimate and represent tropospheric and ionospheric corrections from a regional reference network, which can be efficiently disseminated to users through a simplex communication link. First, the uncombined dual-frequency PPP, with external ionospheric constraints derived from international GNSS service predicted global ionospheric map, is used for estimating atmospheric delays with observations from a regional GNSS reference network. Then, the atmospheric delays are properly represented to facilitate real-time transmission by applying a polynomial model for the representation of zenith wet tropospheric corrections, and satellite-specific STEC maps for representing the slant ionospheric corrections. The above results in only simple communication links required to retrieve the regional atmospheric corrections for real-time single-frequency PPP augmentation. Observations from a regional network of 30 GNSS reference stations with inter-station distances of about 70 km during a 1-week-long period, including both quiet and active geomagnetic conditions, are used for generating the regional atmospheric corrections. The results indicate that the average root-mean-square errors of the obtained regional tropospheric and ionospheric corrections are better than 0.01 and 0.05 m when compared with those derived from dual-frequency uncombined PPP, respectively. The positioning accuracy of the single-frequency PPP augmented with regional atmospheric corrections is at 0.141 m horizontally and 0.206 m vertically under a 95% confidence level, a significant improvement compared to single-frequency PPP without atmospheric augmentation. The convergence time is also significantly reduced with 70.4% of the positioning sessions achieving instantaneous 3D convergence.

Simplex High-Speed Morse Coding with Ultra Low Power MSP430

This paper presents the design and implementation of a simplex communication model using high-speed Morse coding. Morse code is a dot and dash code used from the 19th century and prevails for highly secure applications. The objective of this paper is to design effective encoder and decoder circuits for the Morse code which draw less power. The model is implemented by using two microcontrollers – MSP430 for encoding and ATMEGA8 for decoding. The communication between microcontrollers and the end users are established using Bluetooth. The Morse code is transmitted through an optical medium as flashes of light. The light is flashed using an LED and detected using a phototransistor that constitute an optocoupler. The actuator and sensor pair in the optocoupler are varied by using combination of other actuators like IR diode, Laser and sensors like Photodiode. Each of these combinations have been analysed under the presence and absence of external light with varying distances and the resulting characteristics are plotted. This model is very effective for communication in noisy environments and eliminates the necessity of skilled personnel for decoding the message. It enhances the security and reduces the time required for the overall process. The model has been tested with information of various lengths and it has proven successful in performing the desired operation and delivering the correct output in all the cases.

Network Steganography in the DNS Protocol

Abstract This paper presents possibility of using of the DNS (Domain Name System) protocol for creating a simplex communication channel between a malware-infected computer with a compromised DNS server. The proposed channel can be used to steal data or confidential enterprise information secretly.

Система автоматов: композиция по графу связей

The problem of modeling and composing of aggregate systems is considered. The system components are described with finite automata with multiple entries and exits. The communication between automata is described with message passing over simplex communication channels. The system is described with a directed graph of links. Each node of the graph corresponds to automaton of a component and an arc corresponds to a communication channel connecting exit of one automaton with entry of another automaton. Automaton of the graph node in each state can accept multiple messages from its entries (at most one message from each entry) and send multiple messages to its exits (at most one message to each exit). Entries (exits) of the automata not connected to exits (entries) of automata are considered to be external and used for communication between the system and its environment. The automata of the system operate synchronously: on each cycle each automaton performs one transition. A transition of an automaton imposes requirements on states of all its entries and exits (messages in them are specified) and explicitly specifies subset of entries and exits through which the messages are received or sent, respectively. Synchronous communication between automata means that for each link the requirements of the automata connected with this link must conform to each other. It makes possible to describe a wider spectrum of automata behavior. For example, a priority of message receiving: if there are multiple message in the automata entries, it can receive messages with the highest priority and discard the rest of the messages. It also makes possible for the automaton to receive messages regardless of ability to simultaneously send some message to some exit. A composition of the automata of the system according to the graph of links is defined and its associativity is proved. In conclusion, the directions of future research are described.

Тестирование системы автоматов с буферизацией сообщений

The problem of testing of aggregate systems is considered. The system is described with an oriented graph of links. The nodes correspond to automata of the components and arcs correspond to simplex communication channels. The hypothesis of the links is assumed: the graph of links is static and the link structure is error-free. In each state, the automaton can accept and send multiple messages through incoming and outgoing arcs (at most one message through each arc). The goal of testing is to cover transitions of the automata reachable during the system work. It assumed that during testing it is possible to observe the state changes of automata and the messages on the arcs. A simplified system model with only one message circulating is considered at the beginning. On its example we show that the hypothesis on links allows considerably reduce the number of required testing actions from the multiplication of numbers of the component automata states to the sum of these numbers. If the numbers of states of all automata are equal, it gives exponential reduction of the number of test actions. Then the more general model is considered when the system can simultaneously contain multiple messages, but not more than one on each arc. A composition of the system automata is defined and the restrictions on automata making the system deterministic are described. An algorithm of test generation is proposed basing on test filtration generated for covering all transitions of the deterministic composition system. Test is rejected if it covers only such transitions of the components that are covered by the remaining tests. In conclusion, the directions of future research are described.

Система автоматов: условия детерминизма и тестирование

The problem of testing of aggregate systems is considered. The system components are described with finite automata with multiple entries and exits. The communication between automata is described with message passing over simplex communication channels. The system is described with an oriented graph of links. Each node of the graph corresponds to automaton of a component and an arc corresponds to a communication channel connecting exit of one automaton with entry of another automaton. The hypothesis of the links is assumed: the graph of links is static and the link structure is error-free. Automaton of the graph node in each state can accept multiple messages from its entries (at most one message from each entry) and send multiple messages to its exits (at most one message to each exit). An associative composition of the automata is defined. The restrictions on the automata and the graph of links are determined, for which their composition, i.e. the system itself, is deterministic. The goal of testing is to cover transitions of the automata reachable during the system work. It assumed that during testing it is possible to observe the states of automata and the messages on the arcs. The complete testing of the automata system without considering the hypothesis of links may require the number of testing actions of order of multiplication of numbers of states of the component automata, while with the consideration of the hypothesis of links - of order of the sum of these numbers. If the numbers of states of all automata are equal, it gives exponential reduction of the number of test actions. If the hypothesis of links is true, an algorithm of test generation for a deterministic system is proposed basing on filtration of tests generated for covering all transitions of the composition. Test is rejected if it covers only such transitions of the components that are covered by the remaining tests. In conclusion, the directions of future research are described.

Optimization Algorithm of the Repeaters Distribution by Square and Cellular Model

Very high frequency (VHF) is widely used in radio and television broadcasting. In order to improve the quality of service (QoS) and signal transmission distance, the repeaters be applied to lengthen the transmitting distance of VHF and expand the coverage of radio stations. Under ensuring the QoS, the reduction cost is very important. In this paper, focusing on the different coverage of repeaters, we discuss the minimum number of repeaters to cover a whole circular area, and the square model and cellular model are proposed. Then we analyze the case in view of the simplex communication and duplex communication. Furthermore, the influence of the location of the radio station to the minimum number of repeaters needed is discussed. Finally, we discuss how the minimum number of repeaters changes with the change of the numbers of radio stations. The minimum number of repeaters to cover the circle area will increase as the radius of the repeaters coverage decreases. The radio station in the center of the circle flat can broadcast to the farthest area and the radio station in the fringe area can’t broadcast to farther area. In simplex communication, the minimum number of repeaters with n radio stations in the circle are is n-1 times greater than that with only one radio station.

The effect of emoticons in simplex and complex task-oriented communication: An empirical study of instant messaging

Many studies have shed light on general computer-mediated communication, instant messaging (IM), and emotion or emoticons, but little is known specifically about the impacts of emoticons in task-oriented IM communication in the workplace. Therefore, the current study addresses this issue by conducting an exploratory experiment to (1) categorize workplace IM messages into coherent groups, (2) identify the most commonly used emoticons (emblems) for expressing positive, negative, and neutral emotions in the case company, (3) test the differences in the emotional effects of the received text messages with and without emoticons on the reader/s, and (4) examine the intention to use emoticons in IM in the workplace. The results showed that (1) negative emoticons could cause a negative effect in both simplex and complex task-oriented communication, (2) positive emoticons only created a positive effect in complex communication and for female employees in simplex communication, and (3) there is no significant difference between task-oriented messages with or without neutral emoticon. Furthermore, the intention of using emoticons was not statistically significant in terms of gender, but it has a higher tendency on female employees. The corresponding suggestions provided by this research may help increase our understanding on the effect of emoticon use in IM in the workplace.

Study on full duplex communication in distributed measurement and control network based on Datasocket technology

Concerning the characteristic that real time,reliability and remoteness are required in complicated distributed measurement control network communication,DataSocket technology that is widely used in field real time communication was studied.The requirement and method of real time communication based on DataSocket was studied with emphasis,at the same time the model of simplex communication based on DataSocket was presented,and the model of full duplex communication was designed accordingly.It proves that DataSocket technology can solve the problem of real time,reliability and remoteness in complicated distributed measurement control network communication,and can integrate control with measurement in complicated distributed measurement control network communication.

LED location beacon system based on processing of digital images

This paper is in the field of vehicle positioning technology for the intelligent transportation systems. The ideas of an innovative light-emitting diode (LED)-based location beacon system are developed and verified. The system developed is a combination of several latest technologies which include a CMOS vision sensor, high brightness LED, and digital image processing techniques. It belongs to a new kind of simplex communication link. A digital camera is used to capture images contained in the LED beacon signal. The captured digital images are processed by the algorithms developed and a location code is extracted. The location code can be used for calibration of a vehicle positioning system which may consist of a GPS, inertial navigation system (INS) and other sensors. The issues examined include the structure of the transmitter and the receiver, the signaling method, the transmission protocol of the LED panel, the relationship between the camera capturing rate and the LED pattern update rate, the digital camera exposure technology, and the efficiency of the image processing algorithms. Experiments using a prototype transmitter and a receiver were performed. The experimental results provide a good demonstration of the viability of the ideas and methodologies developed.

Hands-free circuitry providing audio signal adjustment based on speaker volume level

A hands-free circuitry in which, in order to prevent howling caused by acoustic coupling between a speaker and a microphone, a loss is inserted in a transmit audio path in a receive mode while a loss is inserted in a receive voice path in a transmit mode and values of the losses are controlled according to the volume set value of the speaker. Since the quantities of the losses are minimized when a howling margin is sufficient, simplex communication can be prevented that a user cannot listen to party's receive voice signal due to excessive attenuation.

Reliability improvement for simplex communication systems with multiple channels : Giuliano Benelli. IEEE Trans. Reliab.R-35 (3), 301 (1986)

Reliability improvement for simplex communication systems with multiple channels : Giuliano Benelli. IEEE Trans. Reliab.R-35 (3), 301 (1986)

Reliability Improvement for Simplex Communication Systems with Multiple Channels

The reliability of a communication system can be improved by using channel coding. Complex coding and decoding are often required to achieve high performance. An alternative approach is channel redundancy in which the same information is transmitted over two or more channels at the same time. In this way, the coding complexity required to achieve a given error probability can be appreciably reduced. However, a decoder is required for each channel. This paper describes a method which uses channel redundancy to obtain higher performance compared to similar systems and requires only one channel decoder.

Multiplexing and Networking Through Fiber Optic Links for Scada Systems

The Supervisory Control and Data Acquisition (SCADA) systems of the future might consist of local computer networks tied together through long haul links, using a packet-switching technique.[2, 3] This paper assesses fiber optic link characteristics as potential components of SCADA systems. Essentially, a fiber optic link is constrained to a simplex communication from transmitter to receiver. Such a simplex link is analyzed for its capability to convey baseband signaling and time-, frequency-, and spectral-division multiplexing.