Transmitter Operation Research Articles

Theoretical Comparison of Different Envelope Elimination and Restoration Transmitter PWM Modulator Configurations to Expand the Possible Antenna Mismatch

The main characteristics of high-efficiency switching-mode solid-state power amplifiers with envelope elimination and restoration (EER) methods depend on all their elements. In this article, we study the influence of the types and parameters of the envelope path low-pass filters (LPFs) on the EER transmitter out-of-band emissions. This article presents for the first time an analysis of EER transmitter operation where the output impedance of the PWM modulator is not equal to zero, as usual (with a one-sided loaded LPF), but is matched with the low-pass filter and the load (with a double-sided loaded LPF). Theoretical comparisons of EER transmitters’ out-of-band emissions were carried out with four envelope path LPF configurations (one-sided and double-sided loaded LPFs with a smooth and sharp transition, respectively), for both the nominal load (broadband antenna) and resonant antennas with a limited bandwidth. The analysis showed that for the case of transmitter operation on a resonant antenna with a limited bandwidth, the preferable option was the use of a sixth-order double-sided loaded LPF with a smooth transition. The use of the proposed modulator configuration allowed the transmitter to operate on an antenna with VSWR = 1.07 at the edges of the transmitted signal band with a minimum LPF bandwidth equal to 5.8 bands of the amplified signal. This could significantly expand its application capabilities and allow one to reduce the PWM clock frequency and increase efficiency.

ULP Super Regenerative Transmitter with Digital Quenching Signal Controller

This paper demonstrates an on–off keying (OOK) super-regenerative quenching transmitter operating in 402–405 MHz MICs band applications. To reduce power consumption, the transmitter is controlled by a novel digital quenching signal controller that generates a digital control signal to start transmitter operation when a baseband signal is input to the transmitter. The digital signal controller consists of an envelope detector, a comparator, and a quench timer designed using a state machine to synchronize the operation between the digital controller and the input baseband signal. The transmitter consists of a Colpitts oscillator operating in double operating frequency followed by a frequency divider by 2; this configuration reduces system area and improves phase noise and signal spectrum. The proposed transmitter is implemented using UMC 130 nm CMOS technology and a 1.2 V supply. Simulation shows that the proposed transmitter can meet MICS band mask specifications with data rates up to 1 Mbps and total power dissipation of 537 uW.

Joint detection threshold adjustment and power allocation strategy for cognitive MIMO radar target tracking

Co-located multiple-input multiple-output (MIMO) radar can track multiple targets in the simultaneous multi-beam mode, where the defocused beams are transmitted to illuminate the whole surveillance space, while focused beams are received to attain a high Doppler resolution. A joint detection threshold adjustment and power allocation (JTAPA) strategy for this mode is proposed. The mechanism of our strategy is to improve the tracking accuracy in the clutter zone by exploiting prior target information, feedback from the filter, to facilitate transmitter and detector operation. The predicted conditional-Cramér-Rao lower bound (PC-CRLB), which provides a much tighter bound for the estimation error than the standard Bayesian CRLB (BCRLB), is derived, normalized and used as the optimization criterion. The Bayesian detection framework is embedded in the derivation to connect the detector with the filter. The optimization model is then established with bounding the transmit power and predetection threshold within intervals. It is shown that the objective function is nonlinear and nonconvex, and a flexible proximal alternating direction method of multipliers (ADMM)-based solver is proposed for solving the optimization model. Simulation results show the effectiveness of the JTAPA strategy, compared with the strategies adopting the tunable detection threshold and/or optimal power allocation (PA). In addition, the results imply that the target distance and the target radar cross section are two main factors that influence the JTAPA results.

106.25-Gbps PAM-4 bidirectional optical sub-assembly module with in-line arrangement of optical and electrical interfaces.

We successfully demonstrate a 106.25-Gbps PAM-4 bidirectional optical sub-assembly for optical access networks, including a driver amplifier and an electro-absorption modulated laser for a transmitter, a photodiode and transimpedance amplifier for a receiver, and an optical filter block. For its implementation, we propose design strategies providing an in-line arrangement of optical and electrical interfaces while ensuring optical alignment tolerance for easy assembly and reducing electrical crosstalk between the transmitter and receiver. Measured receiver sensitivity was <-11.4 dBm for the KP4 forward error correction limit during transmitter operation, and measured power penalty of 10-km single-mode fiber transmission was <0.9 dB.

A 5-pJ/Bit OOK Transmitter Using MEMS-Based RF Oscillator for IoT Application in 180-nm CMOS

An 800-MHz OOK transmitter for short-range Internet-of-Things (IoT) applications is presented in this letter. The OOK transmitter utilizes a microelectromechanical system (MEMS)-based RF oscillator for carrier frequency generation, leading to a hardware- and power-efficient architecture. The transmitter is implemented in a 180-nm CMOS process and delivers −12.4-dBm output power. The power consumption of the MEMS oscillator is only 0.24-mW with 126.3-dBc/Hz phase noise at 100-kHz offset and a figure-of-merit (FoM) of 210.5 dB due to the optimized high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> aluminum nitride (AlN) piezoelectric MEMS resonator. The transmitter can provide a 120-Mb/s data rate of OOK modulation with an energy efficiency of 5 pJ/bit by directly switching ON/OFF the power amplifier (PA). The 175-ns startup time of the MEMS-based oscillator can support very heavy duty-cycle transmitter operation, leading to ultralow average power consumption of 50 nW.

Low‐cost RF 802.11g telemetry for flight guidance system development

This work investigates the potential for off-the-shelf hardware to be used as a very low-cost replacement to the expensive missile test telemetry currently used by military equipment suppliers to develop flight guidance systems. Missile tests are essential to create highly accurate simulation models of the missile flight controls to ensure accuracy of live missile fire and fully controlled stability throughout the flight to ensure the missile only strikes intended targets. Since test missiles are expensive one-shot devices the telemetry gathered must be transmitted robustly over the full flight. Development of bespoke telemetry units is expensive; thus the potential for using off-the-shelf components and sub-assemblies to provide telemetry based on the Wi-Fi communications standard is investigated. Over the course of missile development, this would create remarkable financial savings. This work details the design, development, and testing of a Wi-Fi missile telemetry system with the solution being evaluated against required performance requirements. Received signal strength and packet error rate, indicators of communication link quality, were investigated for increasing distance and for multi-frequency vibration. These tests replicate in-flight parameters for the transmitter's operation. Conclusions are presented along with recommendations for future development work.

РЕАЛІЗАЦІЯ ПРОТОКОЛУ ШИФРУВАННЯ XTEAНА БАЗІ БЕЗПРОВОДОВИХ СИСТЕМ СТАНДАРТУ IEEE 802.15.4

The problem of data security in IEEE 802.15.4 systems on Pololu Wixel devices is solved, examples of hardware and software implementation of encryption and decryption of different devices on the same platform are given. The proposed approaches can be used in the development, implementation and operation of wireless enterprise, industrial, and personal systems. Possible areas of development for this work are related to research on improving encryption algorithms (increasing key length, using asymmetric ciphers, etc.), comparing their performance, and implementing a complete data exchange protocol. During the work there were problems in the implementation of encryption algorithms on low-power processors. During the work, a number of issues were resolved regarding type reduction, addressing, memory space, buffer overflow, and more. Issues resolved with reconciliation of receiver and transmitter operation. Examples of hardware and software implementation of encryption and decryption of different devices based on Pololu Wixel are given in the paper. The basic task of building a secure communication channel by encrypting data in the channel was solved and firmware and application software were obtained to fully validate the devices. In addition, this work has great application potential, since the implementation of encryption in existing systems will have a small impact on implementation and will not affect the project budget, but will dramatically improve the security of data transmission in these networks. The proposed approaches can be used in the development, implementation and operation of wireless enterprise, industrial, and personal systems. Continuing this work may be to test the performance of other protocols on this and similar hardware for systems that may be embedded in short-range wireless communication projects of short-range standards.

The Platform Development of a Real-Time Momentum Data Collection System for Livestock in Wide Grazing Land

In the process of animal husbandry production through grazing, animals are active in large grassland or mountain areas, and it is very difficult to obtain and deal with the information on animal activity and state of life. In this paper, we propose a platform for operation of data transmission and analysis system which gathers activity and status information of livestock. The data collected in real time from integrated livestock sensor modules are anticipated to assist farmers to supervise animal activities and health. While at the same time the improvements of viable farming techniques are expected to reduce the impact of the livestock industry on the environment. For the individual management of target livestock, the data collection system needs a convergence technology with a physical active sensor, a wireless sensor network and solar power technology to cover the wide area of mountains. We implemented a momentum data collection system to collect and transfer the information of ecological and situations of livestock in grazing, which include sensor and communication modules, repeaters with solar panels to cover the problems of communications in wide grazing and a receiver connected to main server. Besides, in order to prevent data collisions and deviations on multiple transmitter operation, we renewed the format of the communication protocol and made a platform to analyze animal activities information by software. Finally, the system and platform were applied and tested in National Rural Development Administration in Republic of Korea.

Generation of UWB Doublet Pulse Based on Directly Modulated Laser and Chromatic Dispersion

An ultra-wideband (UWB) doublet pulse generation technique in the optical domain for UWB-over-fiber systems is presented. Our solution is based on the direct modulation of a semiconductor laser, optical filtering, and chromatic dispersion in a transmission fiber. When the integration of the transmitter in optical access network infrastructure is considered, the transmission length difference, or the difference in accumulated dispersion, is an issue to exactly obtain the desired pulse shape. To solve this problem, we propose to adjust the transmitter operation point, specifically the laser chirp, with respect to the targeted transmission fiber length. Bit error rate measurements prove that doublet pulses can be achieved with fiber length variation from 15 to 40 km of single-mode fiber.

임베디드 리눅스 기반의 휴대용 Http 라이브 스트리밍 전송기 구현에 관한 연구

기존 비디오 라이브 스트리머에 비해서 매우 저렴하고 저전력으로 휴대용으로 쉽게 동작하는 HLS(Http Live Streaming) 전송기를 임베디드 리눅스 기반으로 개발 및 구현하였다. HLS 전송기를 저렴하게 구현하기 위해 Arm11 프로세서 위에 임베디드 리눅스를 운영체제로 포팅 하였고 오픈 소스인 FFmpeg와 Segmenter을 이용하여 HLS 프로토콜을 구현하였다. 노트북, iPhone, android phone, 노트북을 수신단말기로 이용하여 개발한 임베디드 리눅스 기반의 휴대용 HLS 전송기의 성능을 평가하였다. 본 논문에서 개발한 HLS 전송기는 애플사가 제안한 HLS 권고 규격 이상의 성능을 구현하였음을 성능평가 실험을 통해 확인하였다. 본 논문에서 개발한 제품의 활용분야는 실시간으로 현장의 위급상황을 현지 지휘소나 원거리 사령부에 전달해야하는 경우 HLS를 개인이 착용하여 이동하면서 실시간으로 상황영상을 전달하는 분야에 활용될 수 있을 것으로 생각된다. In this paper, for developing and implementing the HLS(Http Live Streaming) transmitter based embedded linux which is operated easily and cheap and lower power, portable in all networks and client environments compared to exist video live streaming transmitters. We design the developed HLS transmitter hardware using the Arm11 core and then porting the Embedded Linux OS(Operating System) and implementing the HLS protocol using the open source FFmpeg and Segmenter. For proving the performance of developed HLS transmitter, we make the testing environment for testing the performance of HLS transmitter including the notebook, iPhone, android Phone, Notebook and then analysis the received video in the client displayer. In this paper, we suggest the developed HLS transmitter performance data values higher than the Apple company's HLS recommended specification values and the picture of developed HLS transmitter operation in the testing environment. The application field of this paper result is that the man who works in the emergency situation take HLS and transmit the live emergency situation to the head quarter using this portable HLS.

ELF/VLF Perturbations Above the Haarp Transmitter Recorded by the Demeter Satellite in the Upper Ionosphere

In the studies of the data received from DEMETER (orbit altitude above the Earth is about 700 km), we detected for the first time electromagnetic perturbations, which are due to the ionospheric modification by HAARP, a high-power high-frequency transmitter, simultaneously in the extremely low-frequency (ELF, below 1200 Hz) and very low-frequency (VLF, below 20 kHz) ranges. Of the thirteen analyzed flybys of the satellite above the heated area, the ELF/VLF signals were detected in three cases in the daytime (LT = 11–12 h), when the minimum distance between the geomagnetic projections of the satellite and the heated area center on the Earth’s surface did not exceed 31 km. During the nighttime flybys, the ELF/VLF perturbations were not detected. The size of the perturbed region was about 100 km. The amplitude, spectrum, and polarization of the ELF perturbations were analyzed, and their comparison with the characteristics of natural ELF noise above the HAARP transmitter was performed. In particular, it was shown that in the daytime the ELF perturbation amplitude above the heated area can exceed by a factor of 3 to 8 the amplitude of natural ELF noise. The absence of the nighttime records of artificial ELF/VLF perturbations above the heated area can be due to both the lower frequency of the heating signal, at which the heating occurs in the lower ionosphere, and the higher level of natural noise. The spectrum of the VLF signals related to the HAARP transmitter operation had two peaks at frequencies of 8 to 10 kHz and 15 to 18 kHz, which are close to the first and second harmonics of the lower-hybrid resonance in the heated area. The effect of the whistler wave propagation near the lower-hybrid resonance region on the perturbation spectrum recorded in the upper ionosphere for these signals has been demonstrated. In particular, some of the spectrum features can be explained by assuming that the VLF signals propagate in quasiresonance, rather than quasilongitudinal, regime. It is noted that the profile and dynamics of the ELF perturbation frequency spectrum conform to the assumption of their connection with quasistatic small-scale electron-density inhomogeneities occurring in the heated region and having lifetimes of a few seconds or more. The possible mechanisms of the ELF/VLF perturbation formation in the ionospheric plasma above the high-latitude HAARP facility at the DEMETER flyby altitudes are discussed.

Evaluating the iLoc indoor localization system: Competition outcomes and lessons learned

iLoc is an ultrasound ranging based indoor localization system deployed at the iHomeLab at Lucerne University of Applied Sciences and the Embedded Systems Lab at Stuttgart University of Applied Sciences. The system tracks humans in AAL scenarios which bear an ultrasound transmitter for example in the form of a name badge. The transmitter can be localized with an average accuracy well below 1 meter, by means of wired reference nodes distributed in the lab rooms. A small battery may suffice for several month of transmitter operation. The original deployment consists of wired nodes. Data and power is supplied via the IPoK fieldbus. Configuration data, i.e. node positions, are measured manually and entered in a database. The system participated at the first EvAAL competition 2011 and reached best accuracy score. iLoc+, A modified system comprising battery powered wireless nodes and an automatic configuration procedure was used at the second EvAAL Competition 2012. Both solutions are compared with focus on obtained accuracy and installation effort, using data from the respective competitions. Results of the comparison are discussed and possible optimizations are outlined. The implications may also be relevant for other positioning technologies in the AAL sector.

A Novel Frequency Control Loop for Tunable Notch Filters

In this paper, a novel frequency control loop system for tunable notch filters is presented. The frequency control loop is designed for automatically tuning a microelectromechancial systems tunable notch filter, which has 22-dB rejection in the notch band and less than 0.8-dB insertion loss over a 5-MHz passband bandwidth in the International Mobile Telecommunications band (2.1 GHz). The filter frequency control loop is based on sensing the reflection phase change of a reference signal (in this case, the transmitter carrier) and is developed to track the transmitter operation frequency.

Radiation belt electron precipitation by man‐made VLF transmissions

Enhancements of drift‐loss cone fluxes in the inner radiation belt have been observed to coincide with the geographic location of the powerful VLF transmitter NWC. In this paper we expand upon the earlier study to examine the occurrence frequency of drift‐loss cone enhancements observed above transmitters and the intensity of the flux enhancements and to demonstrate the linkage to transmitter operation. Our study has confirmed the strong dependence that these enhancements have upon nighttime ionospheric conditions. No enhancements were observed during daytime periods, consistent with the increased ionospheric absorption. We have also confirmed the persistent occurrence of the wisp features east of the NWC transmitter. The enhancements are initially observed within a few degrees west of NWC and are present in 95% of the nighttime orbital data east of the transmitter for time periods when the transmitter is broadcasting. No enhancements are observed when NWC is not broadcasting. This provides conclusive evidence of the linkage between these drift‐loss cone electron flux enhancements and transmissions from NWC. When contrasted with periods when NWC is nonoperational, there are typically ∼430 times more 100–260 keV resonant electrons present in the drift‐loss cone across L = 1.67–1.9 owing to NWC transmissions. There are almost no wisp‐like enhancements produced by the transmitter NPM, despite its low‐latitude location and relatively high output power. The lack of any wisp enhancement for L &lt; 1.6 suggests that nonducted propagation is an inefficient mechanism for scattering electrons, which explains the lower cutoff in L of the NWC‐generated wisps and the lack of NPM‐generated wisps.

Terabus: Terabit/Second-Class Card-Level Optical Interconnect Technologies

In the "Terabus" optical interconnect program, optical data bus technologies are developed that will support terabit/second chip-to-chip data transfers over organic cards within high-performance servers, switch routers, and other intensive computing systems. A complete technology set is developed for this purpose, based on a chip-like optoelectronic packaging structure (Optochip), assembled directly onto an organic card (Optocard). Vertical-cavity surface emitting laser (VCSEL) and photodiode arrays (4times12) are flip-chip bonded to the driver and receiver IC arrays implemented in 0.13-mum CMOS. The IC arrays are in turn flip-chip assembled onto a 1.2-cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> silicon carrier interposer to complete the transmitter and receiver Optochips. The organic Optocard incorporates 48 parallel multimode optical waveguides on a 62.5-mum pitch. A simple scheme for optical coupling between the Optochip and the Optocard is developed, based on a single-lens array etched onto the backside of the optoelectronic arrays and on 45deg mirrors in the waveguides. Transmitter and receiver operation is demonstrated up to 20 and 14 Gb/s per channel, respectively. The power dissipation of 10-Gb/s single-channel links over multimode fiber is as low as 50 mW

OFDM Link Performance With Companding for PAPR Reduction in the Presence of Non-Linear Amplification

Use of companding for peak-to-average-power ratio (PAPR) control is explored for a link involving a nonlinear transmit power amplifier with orthogonal frequency division multiplexing (OFDM). Specifically, the objective of the study was to determine if companding using u-law compression/expansion at the transmitter/receiver, respectively, provides end-to-end performance gains relative to a system without companding. We consider the use of companding to ameliorate the impact of nonlinearities in the transmit amplifier. In the absence of companding, transmitter operation near saturation raises the signal level at the receiver but, because of the nonlinearities in the amplifier response, also results in distortion that impacts overall link performance. As the transmit power is backed-off from saturation, amplifier distortion is reduced, but error components due to lower SNR at the receiver become more significant. When companding is introduced in the system, the system is able to operate closer to saturation without substantial transmit distortion. However, requisite expansion of the compressed signal at the receiver yields noise amplification which can counteract any of the performance gains that would otherwise accrue from the increased SNR at the receiver. At issue is whether or not operating conditions exist (e.g., backoff, SNR, amplifier linearity model, etc) for which companding enhances the end-to-end performance relative to the link performance without companding. System simulation models were employed using Rapp's nonlinear power amplification models, where average symbol distance errors were used as performance metrics. We found that companding can provide very modest performance gains in comparison to systems that do not employ companding. Performance trends were corroborated in a hardware testbed with an amplifier chain, where average bit error rates were experimentally determined.

Optical single-sideband transmitter for various electrical signaling formats

A simple high-speed data transmitter to generate optical single-sideband (OSSB) signals using different electrical signaling formats is presented. The OSSB signal is generated by combining the information signal with the Hilbert transform of that signal, obtained by means of electrical processing. A detailed mathematical model is introduced to evaluate the transmitter performance, considering the generation of OSSB signals with different electrical signaling formats. Two signaling formats are evaluated and compared: nonreturn-to-zero (NRZ) and alternate mark inversion. The optimum transmitter operation conditions, namely bias and drive voltages, are derived according to the signaling format used and confirmed experimentally. Transmission tests conducted using 10-Gb/s OSSB-NRZ signals to assess the improvement obtained by electrical dispersion compensation show a significant mitigation of the dispersion distortion.

A CMOS Ultra-Wideband Impulse Radio Transceiver for 1-Mb/s Data Communications and&amp;lt;tex&amp;gt;$pm$&amp;lt;/tex&amp;gt;2.5-cm Range Finding

A CMOS ultra-wideband impulse radio (UWB-IR) transceiver was developed in 0.18-/spl mu/m CMOS technology. It can be used for 1-Mb/s data communications as well as for precise range finding within an error of /spl plusmn/2.5 cm. The power consumptions of the transmitter and receiver for data communication are 0.7 and 4.0 mW, respectively. When an LNA operates intermittently through bias switching, the power consumption of the transceiver is only 1 mW. The range for data communication is 1 m with BER of 10/sup -3/. For ranging applications, the transmitter can reduce the power to 0.7 /spl mu/W for 1k pulses per second, and the receiver consumes little power. The transceiver design, all-digital transmitter, and intermittent circuit operation at the receiver reduce the power consumption dramatically, which makes the transceiver well suited for applications like sensor networks. The electronic field intensity is lower than 35 /spl mu/V/m, and thus the UWB system can be operated even under the current Japan radio regulations.

ANTENNA IMPEDANCE MATCHING WITH NEURAL NETWORKS

Impedance matching between transmission lines and antennas is an important and fundamental concept in electromagnetic theory. One definition of antenna impedance is the resistance and reactance seen at the antenna terminals or the ratio of electric to magnetic fields at the input. The primary intent of this paper is real-time compensation for changes in the driving point impedance of an antenna due to frequency deviations. In general, the driving point impedance of an antenna or antenna array is computed by numerical methods such as the method of moments or similar techniques. Some configurations do lend themselves to analytical solutions, which will be the primary focus of this work. This paper employs a neural control system to match antenna feed lines to two common antennas during frequency sweeps. In practice, impedance matching is performed off-line with Smith charts or relatively complex formulas but they rarely perform optimally over a large bandwidth. There have been very few attempts to compensate for matching errors while the transmission system is in operation and most techniques have been targeted to a relatively small range of frequencies. The approach proposed here employs three small neural networks to perform real-time impedance matching over a broad range of frequencies during transmitter operation. Double stub tuners are being explored in this paper but the approach can certainly be applied to other methodologies. The ultimate purpose of this work is the development of an inexpensive microcontroller-based system.

DTV Transmitter Installation Experience and Planning

The advent of ATSC digital television (DTV) in the U.S. has created the need to install an entirely new terrestrial transmission infrastructure nationwide. A principal piece of equipment in any television transmission plant is the high-power television transmitter. This paper considers the various challenges to the successful installation of high-power DTV television transmitters and identifies the performance parameters that play an important role in transmitter adjustment and operation. Data excerpted from a recent DTV transmitter are also included to provide an indication of performance levels to be expected.