Noise Requirements Research Articles

A digital servo for ultra-stable laser frequency stabilization.

We present a fully digital servo optimized for ultra-stable laser frequency stabilization. Experiments such as optical clock experiments can achieve high laser frequency stability, imposing high bandwidth, high precision, and low noise requirements on servo systems. The laser system utilizes the Pound-Drever-Hall method, employing an ultra-stable cavity to generate an error signal for servo input. The input is separated into two independent channels, with one channel featuring high feedback bandwidth and the other channel featuring high gain in the low-frequency domain. The process is fully digitized using field-programmable gate arrays with custom-made infinite impulse response filters and proportional-integral-derivative algorithms. Thanks to the low latency of 120.5ns and low input noise of 3.22 × 10-12V2/Hz@1Hz, our digital servo can easily lock an external-cavity diode laser to a typical ultra-low expansion ultra-stable cavity. The laser system has a fractional frequency stability of 10-16@1s, with the servo electrical noise contributing only 5.54 × 10-18@1s.

Neuronal Multi Unit Activity Processing with Metal Oxide Memristive Devices

AbstractIntra‐cortical brain‐machine interfaces (BMIs), able to decode neural activity in real‐time, represent a revolutionary opportunity for treating medical conditions. However, traditional systems focusing on single‐neuron spike detection require high processing rates and power, hindering the up‐scaling for neurons‐population monitoring in clinical application. An intriguing proposition is the memristive integrating sensor (MIS) approach, which uses resistive RAM (RRAM) for threshold‐based neural activity detection. MIS leverages analogue multi‐state switching properties of metal‐oxide RRAM to compress neural inputs by encoding above‐threshold events in resistance displacement, facilitating efficient data down‐sampling in the post‐processing, enabling low‐power, high‐channel systems. Initially tested on spikes and local field potentials, here MIS is adapted to process multi‐unit activity envelope (eMUA)—the envelope of entire spiking activity—which has recently been proposed as crucial input for real‐time neuro‐prosthetic control. Prior necessary modifications to the MIS for effective operation, this adaptation achieved over 95% sensitivity across two types of metal‐oxide devices: Pt/TiOx/Pt and TiN/HfOx/TiN, proving its platform‐agnostic capabilities. Furthermore, towards the integration of MIS with silicon chips, it is shown that it can reduce total system power consumption to below 1 µW, as RRAM encoding stage relaxes the signal preservation and noise requirements that challenge traditional complementary metal‐oxide‐semiconductor (CMOS) front‐ends. This eMUA‐MIS adaptation offers a viable pathway for developing more scalable and efficient BMIs for clinical use.

Solar Plasma Noise in TianQin Laser Propagation: An Extreme Case and Statistical Analysis

TianQin (TQ) proposes to detect gravitational-wave signals by using laser interferometry. However, the laser propagation effect introduces a potential noise factor for TQ. In this work, we used magnetohydrodynamic (MHD) simulations to obtain the space magnetic field and plasma distributions during an extremely strong solar eruption, and based on the MHD simulation result, we investigated laser propagation noise for TQ. For the extremely strong solar eruption event, we find that the laser propagation noise closely approaches 100% of TQ’s displacement noise requirement for the Michelson combination, while the laser propagation noise is still about 30% of TQ’s displacement noise requirement for time-delay interferometry (TDI)-X combination. In addition, we investigate the laser propagation noise for 12 cases with different solar wind conditions. Our finding reveals a linear correlation between the laser propagation noise and several space weather parameters, e.g., solar wind dynamic pressure, Sym-H, and Dst, where the correlation coefficients for solar wind dynamic pressure are strongest. Combining the cumulative distribution of solar wind dynamic pressure from 1999 to 2021 with the linear correlation between solar wind dynamic pressure and laser propagation noise, we have determined that the occurrence rate of the laser propagation noise to be greater than 30% of TQ’s displacement noise requirement for the Michelson combination over the entire solar activity week is about 15%. In addition, we find that TDI can suppress the laser propagation noise, and reduce the occurrence rate of the laser propagation noise exceeding 30% of TQ’s requirement to less than 1%.

Implementation of preamble based GFDM prototype for robust 5G systems

AbstractGeneralized frequency division multiplexing (GFDM) is a flexible block‐structured multi‐carrier scheme recently proposed for next‐generation wireless communication systems. There are various approaches suggested for its analysis and implementation via simulations but testing in real‐time environments is not heavily investigated. This paper carries out the real‐time implementation of the GFDM system utilizing software‐defined radio (SDR) by emphasizing mainly channel estimation and synchronization. Symbol timing, frequency offset, and channel estimate algorithms are applied using a windowed preamble with two identical halves to satisfy low egress noise requirements. Time and frequency estimation is evaluated in terms of residual offsets along with symbol error rate over frequency selective channels. This algorithm is extended to a preamble composed of multiple identical parts. This facilitates a large frequency estimation range at the cost of complexity. For practical validation of the above concepts, the National Instruments (NI) universal software radio peripheral (USRP) 2953R is employed as hardware and it is interfaced with LabVIEW.

Frequency noise suppression of the high-power pumping laser in the SERF atomic magnetometer

Abstract A high-sensitivity SERF atomic magnetometer based on a noise-suppressed master oscillator power amplifier (MOPA) system is demonstrated. The spectrum and frequency noise of the laser are measured and it is proved that the frequency noise in the MOPA system is affected by the amplified spontaneous emission (ASE) stimulated from the power amplifier. The frequency noise of the MOPA system is decreased by filtering out the ASE background in the spectrum through a bandpass filter. The sensitivity of the SERF atomic magnetometer is improved by using the frequency noise-suppressed MOPA system as a pumping laser. This method can also be applied to other precision measurement fields based on the MOPA systems that have high requirement for frequency noise of laser.

Rooftop pools - a problem from an acoustic point of view: how to identify and solve it

There is no standard with specific methods for acoustic testing of rooftop swimming pools in Brazil. On the other hand, although the compatible requirement for impact noise from rooftop leisure environments is not the type of noise generated by swimming pools, it is a current requirement in the Brazilian performance standard. To study the subject, evaluate possible solutions and improve the state of the art, this article brings measurement results for impact noise in the same situation without and with the application of an acoustic solution. The study also presents sound pressure level and vibration measurements in an environment below a swimming pool after the application of the acoustic solution. Vibrations were measured as well in the pool structure and in the slab below, making it possible to identify the vibrational behavior of the pool. Measurements of impact noise took place in a situation where the pool is three floors above the last residential unit to verify the influence of technical slabs. With the measured values in the three situations, it was possible to identify the frequency range for which acoustic solutions should be designed for this type of source and to monitor the effectiveness of different solutions.

Noise monitoring in primary schools: comparisons between different time-dependent parameters for acoustic performance evaluation

The A-weighted equivalent sound level is commonly used to describe or regulate environmental noise over a defined time interval. Although it is very convenient and easy to compare noise limits or requirements, it does not provide summary information on how noise evolves. On the other hand, the detailed analysis of the history of the measurements over time is too burdensome in the case of long-term monitoring. As part of a large study that aims to investigate the effects of noise on the cognitive abilities of primary school children, long-term unattended monitoring was carried out using low-cost instrumentation based on smartphone apps and calibrated external microphones. From the data obtained, acoustic indices and parameters were calculated, which allowed the assessment of the time-dependent noise exposure of the students based on the type of activity carried out in class. This analysis can be useful for validating the acoustic design requirements in schools.

Prediction and evaluation of the low-frequency noise impact from industrial noise sources

German legislation requires an assessment of low-frequency noise in addition to the regular noise assessment for industrial plants. The detailed prediction and assessment of low-frequency noise immissions is carried out according to the administrative regulation for noise TA Lärm and the German standard DIN 45680. However, a standardised procedure for predictions of low-frequency noise does not exist. For this reason, different approaches for the prediction of low-frequency noise immissions have been developed over the last two decades. Typically, the method according to DIN ISO 9613-2 for sound propagation outside is extended heuristically to the lower frequency range. The predicted low-frequency noise level outside the room is taken as a basis for determining the noise immission level inside the room. The level of knowledge about the quality of sound propagation modeling of low-frequency noise is still debatable. A forecast method of low-frequency noise components should be on the "safe side" in terms of noise control; however, the scope of the required measures to meet the noise requirements must be comprehensible and proportionate. We present an overview of the building blocks of a forecasting process and the challenges that arise. The topic is illustrated by a practical example.

Research on the influence of different organizational structures on the electrical life of sealed relays

Abstract A sealed relay is a type of power relay mainly used in fields with harsh environments, low noise requirements, or high-reliability requirements. It is used in scenarios such as vehicle loads, household appliances, industrial control, and motors. At the same time, when the input meets certain specified conditions, it is a device that can generate a jump in one or more electrical output circuits, playing a role in controlling the on/off current of the connected circuit. Power relays have been widely used in various fields due to their small size, low noise, and low power consumption advantages. This article mainly studies the electrical parameters such as arc energy, arc time, welding force, and contact burning principle of silver tin oxide electrical contact materials produced by different processes, providing a reference for the development of electrical contact materials.

The Medium Energy Electron Telescope (MEET): Instrument Fabrication and Testing

AbstractThis manuscript is a follow up study to Hogan et al., (2024, https://doi.org/10.1029/2023JA032221) which describes the science motivation and development of the Medium Energy Electron Telescope (MEET). Medium Energy Electron Telescope is a 1U instrument optimized to measure 30–400 keV electrons in the inner radiation belt with fine energy resolution to resolve dynamics of these populations which are not well understood. Here we present the fabrication and testing of MEET to certify its performance in preparation for in‐space measurements. Assembly of an engineering model is shown. This unit has undergone vibration testing and these results are discussed. The electronics of the instrument are tested after these environmental tests including electron measurements with pulse injection and a radioactive source. Test results indicate the instrument is viable for flight on a potential mission by satisfying noise requirements and reproduction of an input flux spectrum. The noise of expected input signals is quantified to be <∼6 keV allowing for <20% dE/E for 30 keV electrons. Strontium‐90 radioactive source tests were conducted. Using measured count rates from MEET's electron energy channels, we reproduce the strontium‐90 spectrum proving the instrument's ability to measure flux of 30–800 keV electrons with fine nominal energy resolution (<20% dE/E for <60 keV, and <10% for >60 keV electrons). These results demonstrate MEET's performance in a relevant environment via ground testing. Medium Energy Electron Telescope is available for future missions to provide novel electron measurements in the inner radiation belt.

Technical noise, data quality, and calibration requirements for next-generation gravitational-wave science

Abstract The next generation of ground-based gravitational-wave interferometers is expected to generate a bounty of new astrophysical discoveries, with sensitivities and bandwidths greatly improved compared to current-generation detectors. 
These detectors will allow us to make exceptional advancements in our understanding of fundamental physics, the dynamics of dense matter, and the cosmic history of compact objects. 
The fundamental design aspects of these planned interferometers will enable these new discoveries; 
however, challenges in technical noise, data quality, and calibration have the potential to limit the scientific reach of these instruments.
In this work, we evaluate the requirements of these elements for next-generation gravitational-wave science, focusing on how these areas may impact the proposed Cosmic Explorer observatory.
We highlight multiple aspects of these fields where additional research and development is required to ensure Cosmic Explorer reaches its full potential.

Research on Vibration and Secondary Noise Characteristics of Sensitive Buildings Along Metro Lines Induced by Metro Operation

With the rapid development of urban rail transit, the environmental vibration and secondary noise induced by metro train operation have become increasingly serious, posing stricter requirements on the vibration and secondary noise of sensitive building office (SBO) and sensitive building school (SBS). To predict and control the vibrations and secondary noise in sensitive buildings along the metro line induced by metro train operations. A prediction method for the vibration and secondary noise of sensitive buildings along the metro line during metro train operation has been proposed. The sub-model of train-track system coupled dynamics and the sub-model of track-tunnel-soil-building system dynamics are included. The influence of metro train operation on the vibration and secondary noise of SBO and SBS is studied. The influence of the distance between the metro line and the building on the vibration and secondary noise of the sensitive building is discussed, and an effective control scheme of vibration and secondary noise is proposed. Results show that the vibration frequencies of the SBS and the SBO caused by the metro train operation are concentrated at about 8[Formula: see text]Hz and 63[Formula: see text]Hz. The vibration below the second floor of SBO caused by the metro train operation exceeds the limit, and the secondary noise below the third floor of SBS exceeds the limit. The secondary noise inside the building of each floor of SBO exceeded the limit. Using secondary noise to evaluate the environmental impact of metro train operations is more stringent than relying solely on vibration assessments. secondary noise is recommended in engineering to assess the impact of metro train operation on sensitive buildings along line. Combined with vibration, secondary noise and construction requirements, SBS and SBO are recommended to be no less than 72[Formula: see text]m and 74[Formula: see text]m away from the metro line, respectively.

MODEL PERAMALAN PERGERAKAN PENUMPANG DOMESTIK DI BANDAR UDARA YOGYAKARTA INTERNATIONAL AIRPORT

This research is quantitative descriptive research which aims to make predictions using the ARIMA model time series forecasting method. The data obtained was analyzed using the R program. The data used for forecasting is the number of arrivals and departures of domestic passengers at Yogyakarta International Airport for the period January 2022 – December 2023. Based on the results of data analysis, it is known that the ARIMA model time series forecasting method is the best for predicting the number of arrivals. and domestic passenger departures at Yogyakarta International Airport are the AR (1,0,0) model. This method was chosen because the results were significant, met the white noise requirements and had the smallest MAPE value.

Tunnel Ventilation Silencer Replacement Project

Silencers play a major role on road and rail tunnel ventilation projects throughout North America and the globe. They are instrumental in acheving the required dBA levels; specifically for emergency announcements. Vibro-Acoustics was called to replace silencers that began rusting internally. This caused metal pieces to break off during fan operation. Blade strikes were discovered by maintenance personel which promped an entire replacement task. This was a challenge in itself to remove the existing silencers and install new ones in their place as many space restrictions were present. The new silencers had to be fabricated in a way to meet the stringent acoustic requirements but also for ease of installation. They consisted of 84" inlet and 144" discharge lengths to acheive the noise requirements both at the track level and nearly street level. The silencers consisted of 3/16" plate casings and G235 18 gauge baffles as per the engineers specification. This presentation will show the steps taken to remove the old silencers, the challenges of installing the new silencers, and the testing process for ceritfiying the acoustic performance by a third party acoustical consulant located in NYC. Vibro-Acoustics was involved throughout the entire project which dates back to 2018.

Study of an MoS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\hbox {MoS}}_{2}$$\\end{document} phototransistor using a compact numerical method enabling detailed analysis of 2D material phototransistors

Research on two-dimensional material-based phototransistors has recently become a topic of great interest. However, the high number of design features, which impact the performance of these devices, and the multi-physical nature of the device operation make the accurate analysis of these devices a challenge. Here, we present a simple yet effective numerical framework to overcome this challenge. The one-dimensional framework is constructed on the drift-diffusion equations, Poisson’s equation, and wave propagation in multi-layered medium formalism. We apply this framework to study phototransistors made from monolayer molybdenum disulfide (MoS2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\hbox {MoS}}_{2}$$\\end{document}) placed on top of a back-gated silicon-oxide-coated silicon substrate. Numerical results, which show good agreement with the experimental results found in the literature, emphasize the necessity of including the inhomogeneous background for accurately calculating device metrics such as quantum efficiency and bandwidth. For the first time in literature, we calculate the phase noise of these phototransistors, which is a crucial performance metric for many applications where precise timing and synchronization are critical. We determine that applying a low drain-to-source voltage is the key requirement for low phase noise.

The impacts of phase noise on a long-baseline cross-eye jammer

Cross-eye jamming is a technique used for deceiving the angle measurement of monopulse radars. Long baseline (i.e., long spacing of jammer antennas) is an attractive option for cross-eye jammers, which can increase the angular error for monopulse radars. Phase error is a key factor restricting the performance of cross-eye jammers. In this paper, one of the sources of the phase error, i.e., local oscillator (LO) phase noise, is analyzed for a long-baseline cross-eye jammer. The effect of LO phase noise on the jamming performance is revealed for the first time. Additionally, the tolerance requirements for the LO phase noise of long-baseline cross-eye jammers are determined through theoretical analyses. Finally, the theoretical analyses are verified by Monte Carlo simulations. The research results can provide theoretical insights for system design and component selection for cross-eye jammers.

The Impact of Sick Building Syndrome and Physical Air Quality on Staff Productivity in the Hospital's Outpatient Room of Rumah Sakit Umum Daerah Haji Indonesia

Introduction: The concept of SBS as an occupational health problem is related to air pollution, inadequate ventilation, and indoor air quality in office buildings. Lighting in the RSUD Haji Building still does not meet general and local lighting standards. Complaints of eye fatigue are also felt by administrative staff in the outpatient room of the RSUD Haji Indonesia. This research aimed to examine how physical air quality and sick building syndrome give impact to officer productivity in the outpatient room of the RSUD Haji Indonesia. Methods: This kind of study used a cross-sectional design and was observational. Simple random sampling was utilized in the sampling process, and logistic and linear regression were used to analyze the data. Results and Discussion: Lighting in outpatient rooms that is 100% compliant with standards. The percentage of rooms without proper temperature norms was 21.42%. The rate of rooms with inadequate noise requirements was 17.86%. Spaces without 50% relative humidity norms. SBS symptoms: 10.3% of respondents said they always had itchy skin, and 27.6% said they frequently experienced extreme stress and exhaustion symptoms. Conclusion: There was no effect of temperature, lighting, or noise in the room regarding the sick building syndrome symptoms of officers in the outpatient room, except humidity. However, most workers felt SBS symptoms. Officer productivity was not impacted by the physical quality of the air or by sick building syndrome symptoms.

Design and Testing of a Fast-Response Preamplifier

This article presents the design of a high-speed, low-noise preamplifier specifically intended for amplifying high-frequency weak electrical signals. Firstly, a thorough analysis was conducted on common types of preamplifiers, and it was proposed to adopt a charge-sensitive preamplifier as a solution for signal output amplification. Subsequently, a specific circuit was carefully designed and thoroughly analyzed to ensure it meets the strict requirements of low noise and nanosecond-level response. To verify the feasibility of the designed amplification circuit, an actual circuit board was fabricated and electronic tests were conducted. The test results revealed that the electronic noise of the amplifier was only 5mV, and the signal response time was within 5ns, fully demonstrating its excellent performance.

Research on the tilt-to-length coupling noise suppression method inside the gravitational wave detection telescope.

As an integral component of the laser interferometry measurement system, the tilt-to-length (TTL) coupling noise inside the telescope stands out as a critical noise factor that requires meticulous consideration. In the TianQin project, the non-geometric TTL-coupled noise inside the telescope should be less than 0.22 pm/Hz1/2. Additionally, the wavefront aberration RMS at the small pupil of the telescope needs to be better than 0.0065 λ. These requirements set for the telescope are exceptionally stringent. To address this challenge, this study aims to relax the wavefront aberration requirements by mitigating non-geometric TTL coupling noise, while ensuring the non-geometric TTL coupling noise remains below 0.22 pm/Hz1/2. By controlling the coupling aberration proportion, the wavefront aberration RMS at the small pupil of the telescope can be relaxed to 0.014 λ. Alternatively, optimizing the Gaussian beam waist radius can relax the wavefront aberration RMS to 0.016 λ. By simultaneously utilizing two optimization methods, the wavefront aberration at the small pupil of the telescope can be reduced to 0.033 λ, resulting in an impressive success rate of 91.15% in meeting the noise requirements.

Global optimization of multilayer dielectric coatings for precision measurements.

We describe the design of optimized multilayer dielectric coatings for precision laser interferometry. By setting up an appropriate cost function and then using a global optimizer to find a minimum in the parameter space, we were able to realize coating designs that meet the design requirements for spectral reflectivity, thermal noise, absorption, and tolerances to coating fabrication errors. We also present application of a Markov-Chain Monte Carlo (MCMC) based parameter estimation algorithm that can infer thicknesses of dielectric layers in a coating, given a measurement of the spectral reflectivity. This technique can be a powerful diagnostic tool for both commercial coating manufacturers, and the community using dielectric mirrors for precision metrology experiments.