See Page 1 | 2 | 3 of the December 2017 homepage archives.

Thursday 21

Luminescent Paint Makes LiFi Networks More Secure

"'Smart paint' containing fluorescent and phosphorescent pigments could extend the possibilities of proposed LiFi networks, report a team led by K S Narayan at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bengaluru, India. The researchers analysed the effect of nearby luminescent surfaces on the noise characteristics of visible light communication system (VLC) signals, and found that secondary emission could limit bandwidth locally by overwhelming receivers ..."

Radar Sees Through Walls by Seeking Symmetry

"Through-wall-imaging (TWI) technologies do just what their name suggests: Allow users to 'see' through walls. Most radar offerings, however, call for a range of frequencies - a broad capability that increases costs. Current TWI systems also require advanced knowledge of the wall's materials; software frequently predicts how a given barrier will affect the scanning wave, separating echoes and distortions from the solid objects being sought. Using a narrow band of microwave frequencies, researchers at Duke University ..."

Mechanical Filters

Mechanical filters of the type described in this 1969 Electronics World article are yet another example of the genius of some people. They are actually a form of electromechanical device in that the applied electrical signals are first converted into mechanical signals, followed by resonant mechanical elements that discriminate according to frequency, and finally a conversion back to an electrical signal is made. It is fundamentally the same principal as a crystal, SAW, or BAW filter, albeit each with distinctly different methods and topologies. Mr. Donovan Southworth, of Collins Radio, presents the basics of mechanical filters in this brief write-up. There is an excellent article on mechanical filters ...

Reindeer Really Do Know How to Fly!

For the past many years, videos have been posted that confirm to all the Doubting Thomases out there what "The Christmas Song" songwriters Bob Wells and Mel Tormé (popularized by Nat King Cole) asserted. This story qualifies as a high tech subject due to the FHSS / DSSS techniques in the ISM band radio systems, and brushless motors using LiPo batteries.

Are Print Magazines Less Important to Engineers?

Microwaves & RF Technical Editor Chris DeMartino has a piece in the 12/17 issue that asks the question, "Are Print Magazines Less Important to Engineers?" He makes the point that increasingly higher percentages of people get most or all of their information online. He also states that many engineers still appreciate a printed page, especially for long articles or anything that should be filed away for later reference. I totally agree, personally preferring a printed magazine to online since I typically scan them cover to cover. Since he, like others, prints a hard copy of some online pages, it shows totally paperless is not yet a reality. However, if you have the option to print just a page or two or waste an entire magazine of ink, paper, and delivery service, the former seems less wasteful much more eco-friendly ...

Adding a Bit of Artificiality Makes Graphene Real for Electronics

"In the last few years, a new form of graphene has garnered increasing interest. Dubbed 'artificial graphene,' this latest addition to the 2D landscape is not formed from a single atomic layer of graphite. Instead it is synthesized from other materials to have the same honeycomb lattice molecular structure as graphene, but modified to have specific electronic properties. Now a team of researchers from Columbia University and colleagues from Princeton and Purdue Universities along with those from the Instituto Italiano di Tecnologia in Italy has taken the next step ..."

Wednesday 20

Ceramic Filters

The introduction of low cost, small-footprint ceramic filters were unquestionably a boon to efforts at reduction in end-product package size and manufacturing cost. Very good Q and selectivity, no tuning required, and good temperature stability made them perfect for use as IF filters in broadcast radio receivers, at 10.7 MHz (FM) and 455 kHz (AM). They became available for commercial use around 1960. This publically available paper published in 2000 from the IEEE provides some historical perspective to ceramic filters: The History of Ceramic Filters, by Satoru Fujishima. The Clevite Corporation, for which this ...

Mini-Circuits December News & Product Highlights

Mini-Circuits announces the availability of four new devices in its lineup of RF and microwave components. Included are a precision SMA connector gauge kit, a 2.4 mm (female to female) adapter covering DC to 50 GHz for industry-leading value, a miniature lumped element lowpass filter that passes DC to 83 MHz with sharp rejection , and a tiny LTCC lowpass filter that passes DC to 8440 MHz 

Tower Companies to Benefit from Tax Reform, Emergence of IoT

"Tax reform and the emergence of the IoT are two reasons for tower companies to be grateful this holiday season. Cutting taxes has become a top priority for Congress under Donald Trump's administration, and wireless carriers - like companies in countless other industries - are very much in favor of the move. AT&T CFO John Stephens said recently that his company is 'optimistic about tax reforms,' and T-Mobile CFO Braxton Carter said last week that T-Mobile likely wouldn't be in a position to pay cash taxes for roughly the next ..."

Triad RF Systems Intros a 1.3-1.4 GHz, 20 W Dual Bidirectional Amplifier

Triad RF shipped our latest Dual BDA, the L-band TTRM1081D. This unit is compatible with all military and commercial radios and provides over 20 W of linear RF power across 1.3 to 1.4 GHz. Made specifically for multi-in-multi-out (MIMO) radios, providing 2 radio ports and 2 antenna ports, each providing 5 W of 64 QAM power and over 20 W peak power. The BDA operates off a single +28 V supply and provides 25 dB of TX gain and 11 dB of RX gain in both channels. This class AB LDMOS module is designed for both military and commercial applications 

National's Company - Merry Christmas and Happy New Year

This full-page advertisement by the National's Company (not sure why the apostrophe was included) wished a Merry Christmas and a Happy New Year to QST magazine readers. National manufactured a lot of amateur radio equipment at the time, along with some commercial gear for mobile and home radio. Evidently no fewer than 41 licensed Hams worked at the company since their names are listed. That helps to explain the huge popularity of National's products in the hobby. National Company went to the expense of having a 1940 Christmas Seals stamp affixed in the upper left corner of the page. I was surprised to see the stamp and at first thought maybe the previous magazine ...

Signal Reception with Antenna Diversity w/Multiple High Speed DACs

"In modern wireless systems, numerous diversity techniques are used to maximize data throughput and improve transmission reliability. Time, frequency and code diversity techniques are used to transmit signals to multiple users simultaneously and to maximize the amount of data transmitted. By transmitting at different times, on different frequencies, or with different binary sequences known as Gold codes, signals are produced so that they can be differentiated from each other and can be received error free. These techniques are widely ..."

Tuesday 19

Keysight Technologies at DesignCon 2018

Please save the date and join Keysight as the proud host sponsor at . Keysight's technical experts and application engineers will demonstrate the most advanced design and test solutions, developed to solve today's most difficult high-speed digital measurement challenges. What: Keysight at DesignCon 2018, Where: Santa Clara, CA Convention Center, When: January 31st - February 1st, 2018 

Many Thanks to ConductRF for Continued Support!

ConductRF is continually innovating and developing new and improved solutions for RF Interconnect needs. See the latest TESTeCON RF Test Cables for labs. ConductRF makes production and test coax cable assemblies as well as standard & precision RF connectors. Over 1,000 solutions for low PIM in-building to choose from in the iBwave component library. They also provide custom coax solutions for applications where some standard just won't do. Please visit ConductRF today to see how they can help your project!

Analog Logic

Whenever I read the April issue of any magazine, vintage or contemporary, lurking in my mind is whether it is an attempt at an April Fools "gotcha." The article title is usually the first clue that the author is trying to punk me at least provides a sporting chance. Take for instance this "Analog Logic" piece in the April 1972 edition of Popular Electronics. It could easily be a hoax, so I proceeded cautiously. It turns out to be completely legitimate. James Hannas provides a few examples of how analog circuits can be used to perform mathematical functions that are easily handled by logic circuits. Of course prior to the introduction of readily available ...

MLinkPlanner Microwave Communications Link Planning Software

Mr. Oleg Sakharov, Director of the Center of Telecom. Technologies, LLC, recently sent me information on the MLinkPlanner software for performing microwave communications link design. Judging only from the provided screenshots and the online documentation, MLinkPlanner looks to be very user friendly and loaded with features. I downloaded the 7-day free trial and did a quick fictitious link between my house in Erie, PA, and the WBEN AM radio station in Buffalo, NY. My route is mostly over Lake Erie, so there was not much in the way of obstructions, other than the curvature of the earth ...

3-D Printed Objects Connect to WiFi Minus the Electronics

"Researchers from the University of Washington have successfully created a new breed of 3-D printed objects. These plastic objects and sensors are capable of collecting all sorts of data, as well as communicating directly with other devices on WiFi. Thanks to models the team is making available to the public, users will be soon be able to create 3-D objects of their own. Although these devices will be made from commercially available plastics, they will have one particularly unique feature: they will be able to wirelessly communicate with other smart devices ..."

Monday 18

SK Telecom's Fronthaul Technology Adopted as 5G Standard in Korea

"Small and mid-sized equipment vendors will have a more receptive environment in which to do business in Korea thanks to SK Telecom's fronthaul technology being adopted as a Korean national standard, according to the operator. Specifically, SK Telecom's newly developed 5G network technology was adopted by the Telecommunications Technology Association (TTA) at its annual conference in Seoul. As SK explains it, a 5G network requires a higher base station density with a higher capacity for data processing than 4G LTE. Such requirements emphasize the significant role ..."

Filters for Microwaves

By the time you get into the realm of microwaves, wavelengths are so short that using discrete components for reactive elements is impractical or impossible. That is where the "magic" of electromagnetic fields kicks in. Prior to the advent of computer simulators, the design, construction, and adjustment of distributed element printed circuit boards and waveguide were not for the feint of heart. Whereas "seat-of-the-pants" tactics often resulted in a successful circuit, guesswork was (and still is) too expensive in terms of time and materials to be employed in the spectrum at and above microwaves. This article from a 1969 issue of Electronics World magazine is ...

Reeve Observatory: Papers Related to Radio and Radio Astronomy

RF Cafe visitor Dick L., a Ham radio operator, wrote to let me know about a website he finds useful for his interest in radio astronomy. The Reeve Observatory, located in Anchorage, Alaska, is apparently the personal project of registered electrical engineer Mr. Witham Reeve, who has authored books for the IEEE Telecommunications Handbook Series. Write-ups and lots of photos (including nifty antenna setups) and plots are posted on the topics of lightning, geomagnetism, radiation, radio science, space weather, and more. You might like taking a few minutes to look around ...

Anatech Electronics' December Newsletter

Anatech Electronics, a manufacturer of RF and microwave filters, has published its December newsletter. In it, Sam Benzacar writes his annual "RF and Microwave: The Year in Review." He addresses the emerging technologies that are actually making 5G a reality in spite of the seemingly insurmountable obstacles presented by the realities of physics. We've been there before with other newfangled technologies; i.e., Bluetooth. Sam has a very quotable line regarding the driverless vehicle craze, "And for laughs, there's always driverless vehicles, a goal driven (it seems to me) by people 

2D Material Integrates Digital Logic and Memory into One Chip

"Researchers at Stanford University have demonstrated that field-effect transistors made from a single layer of molybdenum disulfide (MoS2) can successfully drive resistive random access memory. The results, which were reported last week at the IEEE International Electron Devices Meeting, represent a key milestone for the blending of memory with logic in a monolithic 3D integrated chip. The chip the Stanford researchers developed is known as a 1-transistor-1-resistor memory cell ..."

Sunday 17

RF Cafe Engineering Crossword Puzzle w/Weekly Headlines December 17

At least 10 clues in this puzzle with an asterisk (*) are pulled from this past week's (12/11 - 12/15) "Tech Industry Headlines" column on the RF Cafe homepage (see the Headline Archives page for help). For the sake of all the avid cruciverbalists amongst us, each week I create a new technology-themed crossword puzzle using only words related to engineering, science, mathematics, chemistry, physics, astronomy, etc. Enjoy ...

Friday 15

Beads Block Noise

The April 1969 issue of Electronics World included a large number of articles on the topic of filter design and use. Included were titles such as "LC Filters," "Practical Operating Limits for Filters," "Filters for Microwave," " Crystal Filters," and others were contributed by experts in the field from industry and academia. This article on the use of ferrite beads for blocking RF signals is more of a sidebar note than an article, but it's still worthy of inclusion. Ferrite beads and toroids are still widely employed for stopping radio frequency interference (RFI) on everything from AC power cords to millimeter ...

Fairview Microwave Waveguide to Coax Adapters for 1.7 GHz to 110 GHz

Fairview Microwave, a supplier of on-demand microwave and RF components, has launched a new series of waveguide to coax adapters that cover a frequency range of 1.7 GHz to 110 GHz in 22 waveguide bands. Typical applications include test benches, instrumentation, high efficiency RF/Microwave transmission, MILCOM, SATCOM, radar and telecom. Fairview's new line of waveguide to coax adapters consists of 77 models in sizes of WR-10 to WR-430. These adapters are offered in a wide selection of waveguide flanges, sizes and materials. They support 10 

Lenny & the Squigtones - "The Jolliest Fat Man"

Most people who were around in the 1970s remember the sitcom "Laverne & Shirley." It was popular as a part of the whole 1950s renaissance that was happening with shows like "Happy Days," "Grease," "American Graffiti," et al, that captured the attention of the parents of we teenagers as well as weselves[sic]. I was being held against my will at Southern Senior High School at the time, and many of the kids adopted a "greaser" lifestyle that included cigarette packs rolled up in t-shirt sleeves and Brylcreem in the hair (mainly just the guys), leather jackets and Keds high-top sneakers (guys and gals), and poodle skirts and saddle Oxford shoes (mainly just the gals). Two weirdo characters, Lenny and Squiggy, made cameo ...

IEEE: Patent Power 2017

IEEE has published its "Patent Power 2017" review of the world's companies' patent portfolios and the influence wielded thereby. The web page includes an interactive table and chart that includes 18 industry scorecards with the top 20 companies in each sector. The thumbnail shown here is with everyone involved, but you can filter out non-relevant (per your definition) industries. Circle size indicated relative patent power for a given country. The U.S. still dominates overall. Apple is the figurative 800-lb. gorilla of electronics patents. Honeywell "owns" aerospace and defense (which surprises me). Intel leads in semiconductors. MIT rules in university patents. Take a look ...

SES Says FCC Should Make C-Band Registration Easier, More Affordable

"C-band satellite service provider SES recently told the FCC that if it wants a more accurate database of satellite earth stations, it should streamline the registration framework to make it simpler and more affordable. As revealed in a Dec. 7 ex parte filing (PDF), SES met with FCC staff on Dec. 5 to discuss midband spectrum and the history of C-band satellite. SES emphasized the benefit of C-band satellite capacity not only to cable operators but to other media industry members as well, explaining that virtually all of the video and audio programming ..."

Thursday 14

Electromagnetic Water Cloak Eliminates Drag and Wake

"Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while simultaneously helping it avoid detection. The idea originated at Duke University in 2011 when researchers outlined the general concept. By matching the acceleration of the surrounding water to an object's movement, it would theoretically be possible to greatly increase its propulsion efficiency while leaving the ..."

NI/AWR Example Highlights Impedance Matching of a 60-GHz Printed Antenna

Impedance matching of high-frequency components is a key part of antenna design that ensures maximum transfer of power between the antenna and the transmitter / receiver circuitry. Antennas can be tuned to resonate at the desired frequencies much more quickly and efficiently by first designing a matching circuit rather than by making modifications to the antenna's physical dimensions. A new application example describes a unique design flow using NI AWR Design Environment Microwave 

Test Equipment Scene: VOM's, VTVM's and TVM's

For most needs to measure voltage, current, and resistance, modern users of test equipment do not need to give much thought to the electrical characteristics of the instrument being used. Other than setting the function switch to the proper position (ohms, volts, amps, milliamps, etc.) and not exceeding the safe input limits, measurement accuracy can usually be assumed to be good to within ±2 to ±5 of the least significant displayed digit. I.e., if the digital display shows 10.000, then the actual value is likely in the range of 9.995 to 10.005. Autoranging even removes ...

Boeing to Install Digital Electronics in E-3 Sentry Cockpit Avionics

"Military avionics experts at the Boeing Co. are moving forward with a project to upgrade the cockpits of U.S. Air Force E-3 Sentry radar aircraft with modern commercially available, digital electronics under terms of a $46.3M order announced Thursday. Officials of the Air Force Life Cycle Management Center at Hanscom Air Force Base, are asking the Boeing Defense, Space & Security segment in Oklahoma City to continue work on the E-3 Airborne Warning and Control System (AWACS) Diminishing Manufacturing Sources ..."

Modelithics Co-Founder Dr. Tom Weller Named IEEE Fellow

Modelithics is pleased to share the news and congratulate , the company's co-founder, on being named IEEE Fellow by the Institute of Electrical and Electronics Engineers. This high designation is given by the IEEE Board of Directors to persons having a history of significant accomplishments in the fields of electrical engineering. Dr. Weller has been recognized for his extensive contributions in the area of advanced RF and microwave modeling techniques for surface 

On-Chip Metal-to-Metal Tunneling Makes Light Without Lasers

"Light made on CMOS chips using quantum tunneling could be used for optical interconnect and chemical sensing, according to physicists at King's College London. Kings College gold nano-rod tunneling The technique involves constructing a ~1 nm gap between two metal electrodes (see diagram), and then using a potential difference to promote electron tunneling across the gap. This tunneling occurs in two forms: elastic and inelastic, King's physicist Dr Pan Wang told ..."

Wednesday 13

How to Tame Electromagnetic Interference in Fabs and Beyond

"Electromagnetic interference (EMI) is an increasingly important topic across the global electronics manufacturing supply chain. Progressively smaller geometries of ICs, lower supply voltages, and higher data rates all make devices and processes more vulnerable to EMI. Electrical noise, EMI-induced signal generated by equipment, and factors such as power line transients affect manufacturing processes, from wafer handling to wire bonding to PCB assembly and test, causing millions of dollars in losses ..."

4 Facts About Magnets for Electric Vehicles

"There are four main types of magnets: ceramic (ferrite), AlNiCo, Samarium Cobalt (SmCo), and Neodymium (NdFeB). The latter is one of the most commonly used in motors for hybrids vehicles and EVs. Neodymium magnets have higher remanence, along with much higher coercivity and energy production, but often lower Curie temperature than other types. Special neodymium magnet alloys that include terbium and dysprosium have been developed with higher Curie ..."

Mac's Service Shop: TVI from the Victim's Viewpoint

When I read this installment of Mac's Service Shop, in Popular Electronics magazine, the first thing that came to mind was my own experience with television interference (TVI) when I was a kid. In that case, the transmitter of my radio control system for a model airplane was the culprit. The frequencies and channels are almost exactly the same as reported in this infodrama. In the 1970s, citizen band (CB) radios operated in the 27 MHz realm, as did my R/C transmitter. During summer vacation from junior high and high school, I would run my model airplanes up down the street in front of my house, getting up just enough speed to lift off and then immediately ...

QuinStar Power Amplifiers Boost Radar, Communications, Defense Systems

NASA's Jet Propulsion Laboratory issued the following notice from their NASA Spinoff Database:  Boost Radar, Communications, Defense Systems. As a subcontractor under an SBIR contract from the Jet Propulsion Laboratory, QuinStar Technology Inc. of Torrance, California, developed a solid-state power amplifier of unprecedented efficiency. While most comparable devices lose 20% of their amplified energy when their signals recombine, QuinStar's lose 8%. The solid-state technology 

Beam-Switching Successfully Tested on Predator Drone

"Two satellite beams (or more) are better than one when it comes to data transfer and anti-jamming measures between satellites and drones. At least that's what last month's first successful test of beam-switching technology on an MQ-9 Predator drone seemed to show. Over the course of the testing, the drone flew 1,075 nautical miles and was able to switch smoothly between two spot beams multiple times throughout the trial. While traditional wide-beam satellites use one beam to cover thousands of miles, the satellites ..."

Tuesday 12

High-Density PC Boards

You will probably chuckle at the sight of the printed circuit board being an example used in an article about high density PCB production. However, in 1969 it was heralded as leading edge technology. Remember, though, that surface mount components the size of a grain of salt were unheard of so such a board probably represents a bunch of leaded components being closely packed together with the biggest concern for density being heating / cooling issues. Part of the big deal with this board, when you read the article, is that it is one of eight that were produced on the same substrate and then singulated ...

Cuprate Stripes May Link to Ultrathin Semiconductor Use 'Rust' as Insulator

"Chip makers appreciate what most consumers never knew: silicon's virtues include the fact that it 'rusts' in a way that insulates its tiny circuitry. Two new ultrathin materials share that trait and outdo silicon in other ways that make them promising materials for electronics of the future. Facebook Twitter Email By Andrew Myers The next generation of feature-filled and energy-efficient electronics will require computer chips just a few atoms thick. For all its positive attributes, trusty ...

It's Beginning to Look a Lot Like [a White] Christmas in Erie!

Call me nuts, but I have always loved a white Christmas. That's why most of my life has been spent in northern climes. Judging by the heap on the bird feeder, about 6-8" has fallen so far, and then there's another 6-8" due by tomorrow evening. The pic is from a Wansview 720p webcam (~$40, free access from anywhere) looking out my front window. There's one in the basement, too, for monitoring the homestead when gone. I installed a couple of these webcams at my daughter's house, too - very simple to set up. Now we can see her North Carolina horse farm goings on anytime.

Notable Tech Quote: Werner von Siemens 

"Ideas alone have little worth. The value of an invention lies in its practical implementation." - Werner von Siemens, 1865. The unit of electrical conductance is named after him.

Terminal Radio Corp. Christmas and New Year Greeting

Other than today's QST magazine being a larger format and being printed in full color, there is not much difference fundamentally between the amount of Christmas-themed company advertisements now and half a century ago. Those from the last century were more likely to incorporate a religious message in addition to or instead of a secular message to their customers. Terminal Radio Corporation was located in midtown Manhattan. Google Maps can find West 45th Street and it can find Cortlandt Street, but they evidently no ...

Pentagon Spending More on Emerging Tech

"The Department of Defense spent $7.4B in fiscal year 2017 on cloud computing, big data and artificial intelligence technologies, according to a recent report by public-sector contracting analytics firm Govini. That represents a 32% increase since 2012, with more specific technologies like quantum computing, virtual reality and machine learning seeing some of the bigger boosts in investment. While cloud, AI and big data all saw spending jump over the past five years, AI accounted for the bulk of the increase in spending ..."

Monday 11

Army Developing Lasers That Pierce Fog, Dust to Destroy Targets

"A lot of people think that high-energy lasers, or HELs, can't penetrate fog, rain and dust, said Thomas Webber, director of the Directed Energy Division's Technical Center, U.S. Army Space and Missile Defense Command. That's just plain wrong. The key to making HELs work in poor atmospheric conditions is something called "adaptive optics," he said, adding that the Army is continuing to make more and more improvements on its adaptive optics system ..."

New Invention Could Lead to Novel Terahertz Light Sources

"A new device could open new avenues for the generation of high-frequency radiation with applications in science, radar, communications, security and medical imaging. Ever since the discovery of X-rays in 1895, their ability to reveal things hidden to the human eye has created endless opportunities. But X-rays by far aren't the only option to see the world with different eyes. Researchers hope to make better use of a different form of light, called terahertz radiation ..."

Anatomy of a Lightning Bolt

Mankind has been fascinated with -and scared of - lightning since the dawn of civilization. It's incredible power has been the cause of much destruction and loss of life. Benjamin Franklin famously proved that lightning is in fact a form of electrostatic discharge. He exploited that knowledge to invent grounded lightning rods for tall buildings, thereby nearly totally halting the lightning-caused fire epidemic in Philadelphia and other cities. Much investigation and implementation of lightning discharge mitigation schemes has occurred to safeguard against catastrophic events. Ultimately, though, says author David Heiserman, 'Lightning has ..."

Identifying and Isolating Signals Using Radio Frequency Photonics

An article titled, "Identifying and Isolating Signals Using Radio Frequency Photonics," appeared in the December 2017 issue of Aerospace & Defense Technology magazine. I have not delved much into RF photonics, but evidently the science is gaining popularity, especially as communications shifts to higher and higher frequencies. "Review of Radio Frequency Photonics Basics," also authored by Preetpaul Devgan, contains a lot of good info ...

Thanks to QuinStar Technology for Their Support

QuinStar Technology designs and manufactures mm-wave products for communication, scientific, and test applications along with providing microelectronic assembly, rapid prototyping, and mass customization. Amplifiers, Oscillators, Switches, Attenuators, Circulators, Isolators, Filters, Waveguide, Antennas, Phase Shifters, Transceivers, Mixers, Detectors. QuinStar specializes in cryogenic amplifiers, circulators, and isolators. Please visit QuinStar today to see how they can help your project ...

WiDeo: A Motion Tracing Camera Using WiFi Signals

"WiDeo in operation: The compact WiFi AP in the study integrates WiDeo's motion tracing functionality, and can reconstruct the hand movement made by humans in the living room. WiDeo traces motion even though the AP is separated by a wall and does not have a LOS path to the humans, and doesn't require that the humans have any RF devices on them. WiDeo has broad applications such as security, navigation, search and rescue, and people monitoring ..."