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Making "The Chart of Electromagnetic Radiations"
via Dale

"He once punched a hole in the wall of his home so the planets in his scale model of the solar system would be at precisely the right distance from the sun."
RF  infographics  visualization  people  profile  stories  history 
7 days ago by pierredv
Could beamforming become a problem for 5G? - PolicyTracker: May 2019
"In the second of a series of articles about electromagnetic fields (EMFs) in the age of 5G, we take a look at beamforming. This is considered an essential feature of 5G base station antennas, but some argue that it will mean that current EMF exposure limits need to be reassessed. "
PolicyTracker  health  radiation  EMF  RF 
may 2019 by pierredv
Glass box of atomic vapour could work as a James-Bond-style spy radio | New Scientist, Sep 2018
https://arxiv.org/abs/1808.08589

"David Anderson at Rydberg Technologies in Michigan and his colleagues built their radio receiver to be smaller and more secure than traditional radios. At its heart is a centimetre-sized glass box full of caesium vapour. The caesium atoms are prepared so that some of their electrons have more energy than normal, which makes them highly sensitive to certain frequencies of electromagnetic waves."

"In the new radio receiver, the caesium atoms act as the antenna. When an electromagnetic wave hits the atoms, it temporarily bumps some of their electrons up to a higher energy level, changing the atoms’ quantum state"

"Unlike traditional radio receivers, this compact design works in multiple frequency bands"
NewScientist  RF  antennas 
december 2018 by pierredv
Your USB Serial Adapter Just Became a SDR | Hackaday, Dec 2018
"With a Python script, a length of wire attached to the TX pin, and a mastery of the electron that we mere mortals can only hope to achieve, [Ted] has demonstrated using a common USB to serial adapter as an SDR transmitter."
hacking  SDR  cybersecurity  USB  RF 
december 2018 by pierredv
The Problem With 5G | PCMag.com, John Dvorak, Aug 2018
"The technology might be the problem, but even worse for the companies behind it is the perception that 5G is already unsafe before they even get it on a single pole. "

"It's a bad bet because so little is known about the effects of millimeter waves (30GHz-300GHz). While these frequencies only permeate a small fraction of the human epidermis (the skin), the effect on the cornea, in particular, needs serious research."
5G  RF  health  critique 
october 2018 by pierredv
Radio Frequency-Activity Modeling and Pattern Recognition (RF-AMPR) | SBIR.gov 2018
"OBJECTIVE: The PMW 120 Program Office desires a Radio Frequency Activity Modeling and Pattern Recognition (RF-AMPR) capability to perform pattern recognition, anomaly detection, and improved clustering of radio frequency (RF) signals. Specifically, it shall consist of a parametric RF classifier, a generative model of activity in the local electromagnetic environment, a machine learning-based anomaly detection method, and an RF data-clustering algorithm that classifies data that would otherwise be discarded by the parametric classifier."

"DESCRIPTION: Current automated RF data analysis and information discovery methods necessitate discarding significant volumes of sensor data as “non-analyzable”. This SBIR topic seeks to apply machine learning methodologies to better characterize this discarded data, enabling a more complete understanding of RF activity present in a specific environment."

"Anomaly classification shall include “known unknowns”, radio frequency events that are outliers of known classes, and “unknown unknowns”, anomalous RF events that represent new devices or activities."
SBIR  DoD  RF  spectrum  machine-learning  anomaly-classification  ML  AI 
october 2018 by pierredv
Colosseum: A Battleground for AI Let Loose on the RF Spectrum | 2018-09-15 | Microwave Journal
"In this article, we discuss the design and implementation of Colosseum, including the architectural choices and trades required to create an internet-based radio development and test environment of this scope and scale."
MicrowaveJournal  DARPA  Colosseum  AI  RF  simulation  mirror-worlds 
september 2018 by pierredv
Leading RF Security Vulnerabilities in 2018 — Bastille
Wi-FI: Krack
Keyless entry
Medical devices
Remotely hijacking vehicles

"RF vulnerabilities are most often not the result of flaws in operating systems and applications. The problems often reside in the firmware of communications chips, which are trade secrets not open to public inspection. An attack on them bypasses not just network firewalls but many forms of detection. The vulnerable devices are often simple, mass-produced ones, the kind found on the Internet of Things. Many manufacturers pay more attention to price than security."
Bastille  cybersecurity  RF  Wi-Fi  vulnerability 
september 2018 by pierredv
5G Update: Standards Emerge, Accelerating 5G Deployment | 2018-05-15 | Microwave Journal
"With such closely packed bands and extremely wideband radios, the performance degradation from receiver desensitization is likely with inadequate filtering, PA linearity and harmonic suppression. New NSA 5G NR transmitters can operate with higher output power and higher peak-to-average power ratios for maximum throughput, which may cause problems with co-located 5G receivers in the same base station or nearby 5G devices."
MicrowaveJournal  5G  EMC  coexistence  RF  interference 
june 2018 by pierredv
Exposure of Insects to Radio-Frequency Electromagnetic Fields from 2 to 120 GHz | Scientific Reports
Abstract

Insects are continually exposed to Radio-Frequency (RF) electromagnetic fields at different frequencies. The range of frequencies used for wireless telecommunication systems will increase in the near future from below 6 GHz (2 G, 3 G, 4 G, and WiFi) to frequencies up to 120 GHz (5 G). This paper is the first to report the absorbed RF electromagnetic power in four different types of insects as a function of frequency from 2 GHz to 120 GHz. A set of insect models was obtained using novel Micro-CT (computer tomography) imaging. These models were used for the first time in finite-difference time-domain electromagnetic simulations. All insects showed a dependence of the absorbed power on the frequency. All insects showed a general increase in absorbed RF power at and above 6 GHz, in comparison to the absorbed RF power below 6 GHz. Our simulations showed that a shift of 10% of the incident power density to frequencies above 6 GHz would lead to an increase in absorbed power between 3–370%.
RF  mmwave  NatureJournal 
june 2018 by pierredv
The Radio Frequency Spectrum + Machine Learning = A New Wave in Radio Technology
"The radio frequency spectrum is becoming increasingly crowded and a new DARPA program will examine how leading-edge machine learning can help understand all the signals in the crowd"

“What I am imagining is the ability of an RF Machine Learning system to see and understand the composition of the radio frequency spectrum – the kinds of signals occupying it, differentiating those that are ‘important’ from the background, and identifying those that don’t follow the rules,” said Tilghman.

The RFMLS program features four technical components that would integrate into future RFML systems:

Feature Learning: ...
Attention and Saliency: ...
Autonomous RF Sensor Configuration: ...
Waveform Synthesis: ...
DARPA  AI  RF  spectrum  machine-learning 
november 2017 by pierredv
Power Spectral Density – More is not Necessarily Better (Part 2) - Via Satellite - Nov 2013
"Last month we focused on what power density is and the critical role it plays in the design of today’s satellite communication systems and limiting the amount of interference every satellite terminal experiences during normal operation. In this second and final part, we will describe how this parameter is used to enable use of small or disadvantaged terminals, how easy it is to configure a typical terminal to exceed the limit and cause trouble, and what we as an industry should consider doing to improve the situation. "

"Along with the maximum power density requirement of -14 dBW/4kHz, an off-axis EIRP envelope was added that is defined by the equation 15 – 25 log dBW/4kHz."

"It is now possible to obtain FCC approval for a terminal with an antenna that is not fully compliant with the off-axis antenna gain envelope, provided it is operated in such a way that the off-axis EIRP envelope is not exceeded."
SatelliteToday  satellite  RF  EIRP 
october 2017 by pierredv
Power Spectral Density - More is not Necessarily Better (Part 1) - Via Satellite - Oct 2013
"Power density is the single most important operating parameter for transmitting earth stations and probably the least understood by operators of satellite communication terminals. In this two-part article, we will define what power density is, the role it plays in the design of satellite networks and the licensing of satellite terminals, how easy it is to exceed the regulatory limit and the problems that result and, finally, what we can do to reduce these problems to an acceptable level."

"power density describes how the transmit power in a communications signal is distributed over frequency. It is expressed in terms of power divided by a relatively small unit of bandwidth (e.g. dBW/4kHz) and is usually referenced to the input of the satellite terminal’s antenna. "
SatelliteToday  satellite  RF 
october 2017 by pierredv
Adaptive Coding and Modulation - 2014 ACM testing using channel emulation
"Satellite systems based on the DVB-S standard are forced to adhere to a fixed coding rate and modulation scheme (called MODCOD) among the ones defined in this standard. ... However, the DVB-S2 standard introduced point to point services with the adoption of Adaptive Coding and Modulation (ACM) in order to increase the system capacity."

"ACM is a technique which makes possible to select the optimal MODCOD in real time and for each user independently, according to the state of the propagation’s channel. This is based on the existence of a return link reporting to the emitter side the conditions of the channel, that is the Es/N0."
RF  modulation  coding  MODCOD  DVB  DVB-S 
september 2017 by pierredv
Electromagnetic Compatibility & Wireless Connectivity lab - Koninklijke Philips N.V.
"From workbench and (pre-)compliance to accredited EMC testing, our well-equipped facilities will suit your needs. We support you in building quality into your designs efficiently. Our experts know a wide range of standards, making sure your product complies and is safe to use in all required conditions."
Philips  EMC  testing  RF 
march 2017 by pierredv
RFeye Desktop – the world’s first compact high performance spectrum analyzer — News — CRFS - See through the noise
"CRFS, a leader in real-time RF spectrum monitoring solutions, unveils its next generation 8 GHz RFeye® Desktop. The RFeye Desktop is the first commercially available, high performance spectrum analyzer which is truly portable – it fits in the palm of your hand and can be carried around in your laptop bag"
CRFS  spectrum  measurement  RF 
january 2017 by pierredv
Introduction to Multiscale Modeling in High-Frequency Electromagnetics | COMSOL Blog
In this blog post, we have introduced the idea of multiscale modeling and discussed all of the relevant terms, definitions, and theory that we will need moving forward.
RF 
january 2017 by pierredv
How will 5G impact the RF front end? - RCR Wireless News - Nov 2016
"More MIMO demands and spectrum proliferation mean more filters will be needed, but that will impact power efficiency of the device. Eddy said a state-of-the-art smartphone currently has about 50 filters, but may increase to as many as 200 filters with more antennas and more RF paths – so filters need to be smaller in order to meet design size requirements. While the industry is already shrinking filters compared to their size even two years ago, Eddy said he expects them to become smaller still to meet 5G requirements. However, the high performance needs for 5G will make it difficult for all of that to be done at a low cost, he noted."
RCRWireless  5G  RF  filters 
november 2016 by pierredv
Joint Analysis of Traffic and Channel Power Distributions in 3G Wireless Telecommunications Networks (PDF)
charts of network traffic by site percentile; discussion of Relation Between Loading and Channel Power; definition of Received Total Wideband Power, or RTWP
3G  cellular  RF  engineering  traffic 
july 2015 by pierredv
Ippolito Appendix B: Error Functions and Bit Error Rate - Satellite Communications Systems Engineering - Ippolito - Wiley Online Library
"This appendix provides an overview of error functions and their application to the computation of probability based functions used in communications systems performance parameters. Also included is an approximation error function, which simplifies many of the calculations required for the evaluation of satellite communications system performance. The results are particularly useful in the determination of the probability of error or bit error rate (BER) for many of the processing or modulation techniques discussed in this book. "
RF  reference  information-theory  signal-processing  satellite  communications 
june 2015 by pierredv
NASA-backed collaborative project may revolutionise spectrum monitoring - POlicyTracker May 2015
"BigWhoop, the brainchild of Space Apps Stuttgart, which won a US National Aeronautical and Space Administration (NASA) space applications challenge, aims to create an open-source aircraft and satellite tracking system and much more, developer Andreas Hornig told PolicyTracker. The system will continuously monitor the spectrum between 50 MHz and 2 GHz, using a sensor network with software-defined radio (SDR) devices for ground-based monitoring, according to the abstract of a paper to be presented at the International Astronautical Congress 2015. It's a “citizen science project” limited only by people's imagination people and regulation, Hornig said."
PolicyTracker  BigWhoop  crowdsourcing  RF  sensors  NASA  privacy  surveillance 
june 2015 by pierredv
BigWhoop global spectrum monitoring
"BigWhoop was created at Space Apps Stuttgart. It is not just an app, it is a full system for collecting data from small radio-receivers measuring everything within the radio spectrum around the world. BigWhoop schedules the monitoring, the collection of data via the internet, the database handling and the final analysis as well as visualization. This project solves the Open-source Air Traffic Tracking challenge, but won't stop there."
BigWhoop  crowdsourcing  RF  sensors 
june 2015 by pierredv
4 Fading, Shadowing, and Link Budgets
"Fading is a significant part of any wireless communication design and is important to predict. There are two very different types of fading: small scale fading and large scale shadowing. Small scale fading is often handled in a wireless system with diversity schemes, redundancy, or even retransmit. Large scale shadowing on the other hand is very dependent on location with respect to obstacles, and cannot always be fixed; its modeling consists in predicting the likelihood of outage. We review in this chapter various fading models, we examine how they impact wireless links and how they are modeled in various standards link budgets."
RF  tutorial  fading  shadowing  link-budget  propagation  * 
may 2015 by pierredv
Eb/N0 Explained
Article, " What's All This Eb/No Stuff, Anyway? (Fall 2000) Comments from Phil Karn (April 2007) Questions and Answers on Eb/No (July 2009) Related Links
reference  communication  tutorial  RF 
may 2015 by pierredv
Some RF Infrastructure Implications of IoT - LBA Group blogs, David Horn
"As the evolution of the Internet of Things (IoT) network infrastructure plays out, three important concerns emerge: security, radio frequency (RF) interference, and RF safety. " “Making IP enabled wireless sensors talk to each other without reliability issues will require robust interference cancelling schemes,”
IoT  LBA  RF  infrastructure  interference 
january 2015 by pierredv
Radio Interference from LED Lighting Systems | National Public Safety Telecommunications Council
"NPSTC has been following the issue of interference caused from some LED and fluorescent light system ballasts, which have disrupted both public safety communications and cellular wireless systems. We have also been informed that some USB3 powered computer hubs will cause interference to public safety portable radios operating in the 700 MHz band. NPSTC will publish a formal survey on this topic in early November."
RF  interference  RF  Examples  LED  USB3  NPSTC  fluorescents 
january 2015 by pierredv
Electromagnetic Field Measurement System EMF - Anritsu America
via Tom Brinkoetter "Integrated solution for Electromagnetic Field Strength measurements for health and safety"
Anritsu  field-strength  fieldstrength  measurement  RF 
january 2015 by pierredv
New study: “cell phone sensitives” don’t exist | Ars Technica
"A new study (PDF) in Environmental Health Perspectives addresses claims that some individuals are sensitive to radio-frequency radiation (rf-emf), in this case to the area of the spectrum used by cell phones. Reading it gave me a strange sense of déjà vu, as the methodology of the study closely followed the approach used to explore similar claims in regards to WiFi radiation. In both studies, individuals who claimed to be sensitive were unable to accurately identify when they were being exposed to radiation." "A systematic review of 31 blind and double-blind provocation studies yielded no evidence that IEI-EMF individuals could detect the presence of rf-emf, and only seven studies indicated that exposure to rf-emf did affect health indices (Rubin et al. 2005). In two of these, however, the authors failed to replicate their own findings. Another four studies involved inappropriate use of statistics, while one reported improved mood in the active exposure condition."
ArsTechnica  woowoo  cellular  RF 
january 2015 by pierredv
Vortex radio waves could boost wireless capacity “infinitely” - www.extremetech.com March 2012
Abstract from http://iopscience.iop.org/1367-2630/14/3/033001/article "We have shown experimentally, in a real-world setting, that it is possible to use two beams of incoherent radio waves, transmitted on the same frequency but encoded in two different orbital angular momentum states, to simultaneously transmit two independent radio channels. This novel radio technique allows the implementation of, in principle, an infinite number of channels in a given, fixed bandwidth, even without using polarization, multiport or dense coding techniques. This paves the way for innovative techniques in radio science and entirely new paradigms in radio communication protocols that might offer a solution to the problem of radio-band congestion."
RF  orbital-angular-momentum 
december 2014 by pierredv
Six LTE Receiver Measurements Every Wireless Engineer Should Know | 2014-11-15 | Microwave Journal
Reference Sensitivity Level Maximum Input Level Adjacent Channel Selectivity Blocking Characteristics Intermodulation Characteristics Spurious Emissions
LTE  receivers  cellular  RF 
november 2014 by pierredv
'Space bubbles' may have led to deadly battle in Afghanistan - AAAS Science Mag Oct 2014
"The jagged peaks of Afghanistan have caused plenty of communications difficulties for U.S. forces, but researchers suspect that the doomed rescue mission may have fallen victim to a less visible source of interference: plasma bubbles. Their research, published online this month in Space Weather, suggests that turbulent pockets of ionized gas may have deflected the military satellite radio signals enough to cause temporary communications blackouts in the region." "The Takur Ghar battle occurred during Afghanistan’s “bubble season.” It was a reasonable hypothesis, but proving it might’ve been impossible if it weren’t for a lucky coincidence. At just about the time when things were becoming completely FUBAR atop Takur Ghar, NASA’s Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite had just completed a pass over the area. By using data from TIMED’s Global Ultraviolet Imager, scientists were able to confirm the presence of a plasma bubble between the battlefiel"
spectrum  interference  RF  Examples 
october 2014 by pierredv
DARPA wants more efficient, jam-resistant RF communications -- Defense Systems
"For over a century the military has used radio frequencies for communications, command and control, navigation and radar detection. As the RF spectrum gets more crowded, and as the Defense Department’s reliance on it increases, the military has to deal with two problems: malicious jamming and signal fratricide. In an effort to find solutions to these problems, the Defense Advanced Research Projects Agency has released a presolicitation for advanced microsystems and techniques for jamming-resistant RF communications under its Hyper-wideband Enabled RF Messaging (HERMES) program."
DARPA  HERMES  jamming  RF  communications 
july 2014 by pierredv
Dominant Path Model
See also http://www.awe-communications.com/Propagation/Urban/IRT/index.htm for Intelligent Ray Tracing "Ray-optical propagation models are still very time-consuming – even with accelerations like preprocessing. And what is even more important, they rely on a very accurate vector database. Small errors in the database influence the quality of the prediction. On the other hand, empirical models are – for example- based on dedicated propagation effects like the over-rooftop propagation (COST 231) or on other pre-defined scenarios. As a consequence of these restrictions, a new Propagation Model has been developed, the Dominant Path Prediction Model."
propagation  RF  dominant  path  model  DPM 
june 2014 by pierredv
LA building's lights interfere with cellular network, FCC says | PCWorld
"Fluorescent lights at Ernst & Young Plaza, a 41-story tower near the heart of downtown, emit frequencies that interfere with the Verizon Wireless 700MHz network, the agency said in a citation issued on Friday against building owner Brookfield Office Properties." Citation at http://www.fcc.gov/document/brookfield-office-properties
noise  interference  RF  Examples  cellular  Verizon  fluorescents  General  Electric 
march 2014 by pierredv
Crystal radio: the solution to next-gen comms? :: CriticalComms
"Researchers from the US National Institute of Standards and Technology (NIST) have joined with an international team to engineer and measure a potentially important new class of nanostructured materials for microwave and advanced communication devices. Based on NIST’s measurements, the new materials - a family of multilayered crystalline sandwiches - might enable a whole new class of compact, high-performance, high-efficiency components for devices such as mobile phones." "The new multilayer crystals are so-called ‘tunable dielectrics’, the heart of electronic devices that, for example, enable mobile phones to tune to a precise frequency, picking a unique signal out of the welter of possible ones."
RF  technology  filters  materials  tunable  dielectrics 
january 2014 by pierredv
RF MEMS Switches Are Primed For Mass-Market Applications | Active components content from Microwaves & RF
"tunable RF MEMS filters and antennas will alleviate the present mobile-phone signal loss of 3 to 5 dB in the 700-MHz-to-2.7-GHz band. "
RF  filters  RF-filters  MEMS  interference 
january 2014 by pierredv
Grow light electronic ballasts
Via Dale: "Operations wishing to grow plants indoors need to provide supplemental lighting necessary for photo-synthesis. These lights may be flourescent, LED, and for larger operations high pressure sodium (HPS) or metal halide (MH). The HPS and MH lamps may be 1000W per lamp and require a ballast for proper operation. These ballasts were originally magnetic but in the past few years have become electronic. These devices are subject to FCC part 18 rules but there appears to be a total disregard for the FCC rules. These electronic ballasts are manufactured in China and may have little "FCC" stickers on them but there is no evidence of any testing for compliance having been done."
noise  RF  interference  ballasts  lighting 
january 2014 by pierredv
Is there a (commercial) future for Software Defined Radios ? | The Unwired People
Listening to the talks at the SDR Europe today in Brussels on developments of Software Defined Radios makes me somewhat skeptical. Reprogramming the radios to be able to quickly change the radio access waveforms and protocol sounded like a great idea 10 years ago when there were many competing “3G” air interfaces for mobile communication. As we now see a clear convergence of massproduced equipment to two interfaces, one LTE-typ interface for wide area systems and one that will somehow be containing the numbers “802″ and “11″, for short range communication, there seems to be little space for the use of SDR:s. The industry clearly went the other way and smartphones today contain 6-7 different (non-programmable) radios... SDR:s do not solve the spectrum issue – it is still very hard to build a radio (RF front ends), programmable or not, that can operate over an octave of frequency with reasonable performance.
SDR  spectrum  RF 
december 2013 by pierredv
Understanding Intermodulation Distortion Measurements | Communications content from Electronic Design
"Intermodulation distortion ... or IMD describes the ratio (in dB) between the power of fundamental tones and third-order distortion products." third-order intercept: "The fundamental principle of TOI is that for every 1-dB increase in the power of the input tones, the third-order products will increase by 3 dB.So as one continues to increase the power level of a two-tone stimulus, the IMD ratio will decrease as a function of input power. At some arbitrarily high input power level, the third-order distortion products would theoretically be equal in power to the fundamental tones. This theoretical power level at which first-order and third-order products are equal in power is called the third-order intercept."
National  Instruments  spectrum  tutorial  interference  rf  measurement 
october 2013 by pierredv
Interference Detection and Mitigation with Cisco CleanAir
"The previous blog on CleanAir went in depth on how MSE uses CleanAir information to locate interferers and the impact zone for each interferer. This blog takes a step back and gives an overview of the CleanAir technology." "Cisco CleanAir solution not only detects the source of interference, but also automatically changes the channel on which the WiFi network is operating to a channel clear of interference. " "With Cisco’s CleanAir solution, you can not only detect which interferer is disrupting your WiFi, but also which channels it is affecting and where it is located. The same can be done for multiple sources of interference simultaneously. All this can be done with great accuracy which differentiates CleanAir solution with what the competition offers."
RF  Cisco  interference  Wi-Fi  interference-management 
september 2013 by pierredv
Millimeter Waves May Be the Future of 5G Phones - IEEE Spectrum June 2013
"Samsung’s millimeter-wave transceiver technology could enable ultrafast mobile broadband by 2020" "By dynamically varying the signal phase at each antenna, this transceiver generates a beam just 10 degrees wide that it can switch rapidly in any direction, as if it were a hyperactive searchlight." "In outdoor experiments near Samsung’s Advanced Communications Lab, in Suwon, South Korea, a prototype transmitter was able to send data at more than 1 Gb/s to two receivers moving up to 8 kilometers per hour—about the speed of a fast jog. Using transmission power “no higher than currently used in 4G base stations,” the devices were able to connect up to 2 km away when in sight of one another, says Wonil Roh, who heads the Suwon lab. For non-line-of-sight connections, the range shrank to about 200 to 300 meters."
RF  5G  beam-forming  WiGig  IEEE-Spectrum  Samsung  antennas  mmWave 
july 2013 by pierredv
What is I/Q Data? - Developer Zone - National Instruments
description of modulation, and why I and Q are useful when thinking about phase "I/Q data is merely a translation of amplitude and phase data from a polar coordinate system to a cartesian (X,Y) coordinate system" " What this essentially means is that we can control the amplitude, frequency, and phase of a modulating RF carrier sine wave by simply manipulating the amplitudes of separate I and Q input signals! With this method, we no longer have to directly vary the phase of an RF carrier sine wave. We can achieve the same effect by manipulating the amplitudes of input I and Q signals."
modulation  RF  National  Instruments  tutorial  ex  National  Instruments 
may 2013 by pierredv
Receiver sensitivity/noise tutorial
Discusses receiver sensitivity, SNR, max detection range, noise power, noise factor
RF  sensitivity  tutorial  interference  receivers  noise 
february 2013 by pierredv
2012 Positive Train Control (PTC) Update (pdf)
Wireless PTC Technology White Paper Ramon Abelleyro, STI-CO Industries, Inc.
RF  railroads  PositiveTrainControl  interference  PTC  intermodulation  trains 
february 2013 by pierredv
Rec. ITU-R SM.329-10 (pdf) Unwanted emissions in the spurious domain
See also http://www.itu.int/rec/R-REC-SM.329-10-200302-S; seems to have been superseded, but as of 22 Feb 2013, new one not posted. 4.1 Recommended reference bandwidths A reference bandwidth is a bandwidth in which spurious domain emission levels are specified. The following reference bandwidths are recommended: – 1 kHz between 9 and 150 kHz, – 10 kHz between 150 kHz and 30 MHz, – 100 kHz between 30 MHz and 1 GHz, – 1 MHz above 1 GHz.
ITU-R  RF  interference  reference  bandwidth 
february 2013 by pierredv
Intrado inks deal for 'Apocalypse-proof' HF offering | Intrado content from Urgent Communications
"Public-safety and critical-infrastructure entities soon will have a new option for long-distance, last-resort communications when local and even regional infrastructure is unavailable, as 911 solutions provider Intrado today announced a new product that will leverage high-frequency (HF) spectrum from 3 MHz to 30 MHz."
HF  RF  spectrum  urgentcomm  public-safety 
january 2013 by pierredv
The best time to measure RF interference | Test and Measurement content from Urgent Communications
"So, what is the best method for preventing interference from adversely affecting a system? The answer is to measure the RF environment at a location before a system is installed."
methods  troubleshooting  RF  interference  noise  measurement 
january 2013 by pierredv
Radio interference from LED lighting | EMC and Regulatory Compliance
"although today’s LEDs are capable of long life, and delivering high light output levels with very little power consumption, most need to be paired with a drive circuit to provide constant current sourcing to operate in our homes and offices, and that’s where the problem comes in. These switching drive circuits operate at increasingly higher frequencies, and in order to maintain the highest efficiency, and highest LED longevity possible, they also need to maintain very high slew rates. These factors contribute to the overall unwanted emissions from each individual lighting element, increasing the Electromagnetic background noise. "
RF  interference  LED 
january 2013 by pierredv
FCC Defines DTV ‘City Grade’ Contour - May 2001 - Doug Lung in TV Technology
"How do you define DTV coverage? Since 1997 the FCC has defined it as the 41 dBu F(50/90) contour for UHF stations, 36 dBu for Channels 7-13 and 28 dBu for Channels 2-6. In a Report and Order released earlier this year, the FCC defined a "City Grade" DTV field strength contour and also set minimum signal levels for reception of broadcast DTV signals at cable headends.

This month I’ll explain the FCC’s new coverage definitions and present some tables to allow you to easily see what kind of coverage can be expected from a DTV facility."
TV  FCC  propagation  RF 
june 2012 by pierredv
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