Homepage Archive - December 2016 (page 2)

Friday 30

2016 in Telecoms: The Year That Was

"2016 really was a year like no other. We had yet another election defined by the misuse of analytics - and folks seem to be getting worse rather than better at this. We had a rush to robotics, particularly self-driving cars, and some firms even leaped ahead to self-flying, people-delivering drones (which we called "flying cars" just a few years back). We had a wave of fake news, mostly paid for by Google, because that company, as always, has no compass. It appears to be shaming nations into regulating it, suggesting it has ..."

Anatech Electronics Intros 2 New Filters & 1 Cable Assembly

Anatech Electronics, Inc. offers the industry's largest portfolio of high-performance standard and customized RF and microwave filters and filter-related products for military, commercial, aerospace and defense, and industrial applications up to 40 GHz. Anatech has introduced 2 new filter designs and 1 new coaxial cable assembly: a 6125 MHz cavity bandpass filter with SMA connectors, an L1/L2 GPS duplexer/combiner with SMA connectors, and an MMCX Plug to SMA Female cable using LMR-100A coaxial cable. Custom designs

So-o-o Big! - Latest Fashions in Beams for 144 Mc.

Not all amateur radio operators are inclined toward building and/or servicing electronic equipment, even though a basic level of circuit knowledge is required for earning a beginners' license (Technician level). A little additional circuit theory is added at the General level, and a lot more is required for the Amateur Extra exam. Still many prefer to have their only involvement with receivers and/or transmitters be turning dials and flipping switches. High voltages and easily damaged components inside the chassis ...

Please Visit Triad RF System to Thank Them for Their Support

TriadRF Systems designs and manufactures RF power amplifiers and systems. Triad RF Systems comprises three partners (hence 'Triad') with over 40 years of accumulated knowledge of what is required to design, manufacture, market, sell and service RF/Microwave amplifiers and amplifier systems. "We view Triad more as a technology partner than a vendor for our line-of-sight communications product line." Please check to see how we can help your project ...

Skyrmion Hall Effect Reveal Surprising Spintronics Results

"Researchers at JGU and MIT have made another important breakthrough in the field of future magnetic storage devices. Already in March 2016, the international team investigated structures, which could serve as magnetic shift register or racetrack memory devices. This type of storage promises low access times, high information density, and low energy consumption. Now, the research team achieved the billion-fold reproducible motion of special magnetic textures, so-called skyrmions, between different ..."

Thursday 29

Engineering Webinars Scheduled for January 2017

Five new webinars have been announced for January 2017 by MWJ's "Technical Education Training Series" of free webinars. I will try to remember to post these kinds of event more often.

- A Guide to Making RF

    Measurements for Signal Integrity

    Applications, Jan 24

- Addressing the Challenges of

    Position Sensor Solutions in Safety

    Critical Automotive Apps, Jan 25

- Realizing Efficiency Gains in

    Baseband-to-RF Testing of Remote

    Radio Heads, Jan 26 <more>

2017 Telecoms Predictions: What the Industry Thinks

"While 2016 proved to be a solid year for incremental advancements in 5G, IoT and cloud computing, 2017 is set to be a big year for a number of breakthrough technologies. Figuring out what the next big thing is going to be and investing the right amount of time, money and resource can make the difference between becoming the next Google or simply being forgotten, so we took the chance to ask a few people in the industry what they thought ..."

Sangamo Electric Company Advertisement

A lot of tech news websites have 3rd-party ads running that currently show an ad from a vintage magazine with a shocking title about how companies used to get away with printing images and text in advertisements that would never be tolerated today. I have seen many such ads in vintage electronics and science magazines as I scan them for useful material, and have posted a few of them on RF Cafe. Another example is this one run by the Sangamo Electric Company in a 1949 issue of Radio and Television News. As with the football team ...

Nano System Operates with Interacting Electrons, but No Electric Current

"Illustrating the unusual way things work on the nanoscale, scientists have designed a new nanoelectromechanical system (NEMS) that produces mechanical motion due to the interactions between electrons—yet unlike similar systems, this system does not require any electric current. Instead, the electron-electron interactions couple two electron reservoirs of different temperatures, which generates a heat flow between them that causes a suspended carbon nanotube to vibrate. The researchers, A. Vikström and ..."

World's Smallest Diamonds Made into Wires 3 Atoms Wide

"Scientists at Stanford University and the Department of Energy's SLAC National Accelerator Laboratory have discovered a way to use diamondoids - the smallest possible bits of diamond - to assemble atoms into the thinnest possible electrical wires, just three atoms wide. An illustration shows the basic nanowire building block - a diamondoid cage carrying atoms of copper and sulfur - drifting toward the growing tip of a nanowire, center, where it will ..."

Wednesday 28

Radio Service Data Sheet for the Philco Model 38-116; Code 125

A fair number of these Philco Model 38-116; Code 125 radios are still in existence and have been restored by collectors. I have been scanning and posting Radio Service Data Sheets like this one featuring the Philco Model 38-116; Code 125 for many years now. It is very unusual to have two full pages devoted to a single radio like here. There are still many people who restore and service these vintage radios, and often it can be difficult or impossible to find schematics ...

Russian Anti-Satellite Test

"Russia has reportedly conducted an anti-satellite test in the weeks before a new U.S. president is sworn in. Citing U.S. sources with knowledge of the Russian test, CNN and others reported that the test was tracked and the weapon did not create a debris field. That, the cable network's sources said, indicated the weapon did not destroy a target. There was no official U.S. confirmation of the Russian test, prompting some observers to ..."

Design of Radio-Frequency Transformers

Open up a radio transceiver chassis that operates below 300 MHz (VHF and lower), particularly one built before the advent of highly integrated circuits, and you will almost certainly find many transformers and inductors. Without the advantage of using microstrip type distributed impedance matching, the use of wire-wound transformers and inductors is your only option for tuning filters and implementing interstage impedance matching. In the days of vacuum tubes in all stages of a transmitter and/or receiver, transformers were found in every stage from baseband through RF. Knowing how to ...

IHP Develops World's Fastest Silicon-Based Transistor

"At the International Electron Devices Meeting (IEDM) held in San Francisco from 3-7 December, 2016, IHP introduced the world's fastest silicon-based transistor. The project which was named 'DOTSEVEN,' was funded by the European Union. The four-year project, together with Infineon and twelve other project partners from a total of six countries - focused on developing SiGe HBTs with a maximum oscillation frequency (fmax) of 0.7 THz. The presented ..."

Triad RF Systems 5.0 to 5.3 GHz, 10 Watt Bidirectional Amplifier

The TTRM1074 GaAs amplifier operates at a frequency range of 5000 MHz to 5300 MHz and has a power output of 10 Watts, while still maintaining a compact form factor of 5.3" x 3.25" x 0.57". This unit also features internal protection against over/under voltage and excessive temperature conditions, which coupled with its rugged construction, ensure fault-free operation in even the most extreme environments. It is capable of supporting any signal type and modulation format

Tuesday 27

IEEE to Coalesce Industry, Policymakers, Academia Around 5G

"IEEE is calling on global industry leaders, policymakers and academia to coalesce in a neutral forum to move 5G forward. The purpose of the IEEE 5G Initiative is to engage professionals worldwide to work to solve the challenges associated with 5G and lay the foundation to realize its many opportunities, according to the organization. Volunteers from both industry and academia are being sought as several working groups are being established. '5G is not only evolutionary, providing ..."

Service Sheet for the Stromberg-Carlson Nos. 230 and 231

I have been scanning and posting Radio Service Data Sheets like this one featuring the Stromberg-Carlson Nos. 230 and 231 Series for many years now. There are still many people who restore and service these vintage radios, and often it can be difficult or impossible to find schematics and/or tuning information. This 231R version is unique with its half-round configuration meant to sit at the side if a sofa or chair. It could pass today as a room humidifier ...

DARPA Funds Small Businesses with Big Ideas

"DARPA, the United States' Defense Advanced Research Projects Agency, funds big ideas that sometimes become gigantic successes, after taking on equally gigantic risks (many projects fail). Often groups from universities or researchers get the funds. Now the little guy with a big idea can access DARPA's funding through its Commercial Performer Program, which aims to harness unfunded big ideas from small businesses and individual inventors. "An alluring reach-out strategy, unprecedented within the DoD," said DARPA about non-government entities that ..."

Thanks to VidaRF for Many Years of Supporting RF Cafe!

"At VidaRF, the phrase 'Providing Simple Solutions for Complex Connections' is more than just a slogan – it's a mindset, a mission, and a driving force behind everything we do. Our pledge is to design and distribute high performance, cost effective RF Microwave products to fit each customer's unique applications." Please visit VidaRF today to see how their lines of Attenuators & Terminations, Directional Couplers, Power Dividers, Coaxial Connectors, and Circulator & Isolators can be of use to your project ...

Monday 26

Skyworks Intros AEC-Q100 SPDT Switch for Automotive Apps

Skyworks has unveiled the SKYA21003, a new CMOS silicon-on insulator (SOI) single pole, double throw (SPDT) switch that is targeted for automotive LTE cellular and general purpose RF applications. This next-generation product is AEC-Q100 Grade 2 Qualified with guaranteed RF performance across extended temperature limits, making it an excellent design choice for LTE cellular telematics modems, remote keyless entry devices, infotainment systems, automated toll transponders, garage door openers, GPS/navigation platforms

Fixing the Perception of Engineers

"A new BBC program may have found the ideal formula to make engineering attractive. ­ Two editions of [Big Life Fix with Simon Reeve] have already been transmitted with the third and final installment screened tonight at 9 PM on BBC2. With my usual highly scientific method of gauging reaction to such things (asking friends, family and colleagues) it appears that the series has escaped the notice of many; so if any readers have also missed it, the premise of the series is as follows ..."

A Crossword Puzzle Christmas Greeting from RF Cafe

Christmastime is upon us once again, and amazingly another year is coming to an end. This marks my 58th Christmas here on Earth - that's 58 trips around the sun and a barely measurable distance around the Milky Way galaxy; where has the time gone? "Tempus fugit," as the dial of my grandmother clock proclaims. In fine tradition, this week's engineering crossword puzzle has a special theme that contains a heart-felt message from all the staff (Melanie and me) here at RF Cafe. We hope you had a good 2016 and that you will have a safe and happy holiday season. Carpe diem ...

Friday 23

Graphene Transport Huge Currents on the Nano Scale

"New experiments have shown that it is possible for extremely high currents to pass through graphene, a form of carbon. This allows imbalances in electric charge to be rapidly rectified. Once again, graphene has proven itself to be a rather special material: an international research team led by Professor Fritz Aumayr from the Institute of Applied Physics at TU Wien was able to demonstrate that the electrons in graphene are extremely mobile and react very quickly. Impacting xenon ions ..."

Santa's Reindeers Have Just Been Replaced by a Robot

Nothing says "Merry Christmas" quite like watching Santa Claus being towed on a ski board through the streets of Levi, Finland, by a giant drone.

Determining Meter Shunts and Multipliers

Analog and most digital multimeters rely on precision resistors for scaling the input voltage or current to keep it within the safe operational range of the meter movement or analog-to-digital converter circuit. Resistance value selection is a relatively simple matter of series and/or parallel combinations and their resulting divisions of voltages and/or currents. When this article appeared in 1931, the whole concept of electrical circuit design was entirely new to most people, including shunts and multipliers for meter scales. There is a nice table of resistor values provided, but I was a little disappointed to find that not ...

Nokia Joins Ericsson, Cisco, Huawei in NFV Testing Initiative

"Add another entity to the NFV ecosystem—but don't call it another NFV organization amid several, according to a Nokia spokesperson. Nokia, along with Ericsson, Cisco and Huawei, announced they have signed an MoU to create the NFV Interoperability Testing Initiative (NFV-ITI) in an effort to help service providers address challenges related to NFV deployment and cloud transformation. In the U.S., operators like AT&T and Verizon are implementing NFV and SDN in part so they can improve service delivery ..."

Thursday 22

Merry Christmas from RF Cafe!

 

Many thanks to everyone who supported RF Cafe throughout the year. Advertisers, visitors, purchasers of my software and CafePress gift offerings all play an important part in keeping RF Cafe "On the Air." Have a great holiday season and a safe and prosperous New Year!

"Yes, Virginia, there is a Santa Claus."

OneWeb Raises $1.2B to Build Broadband Access Satellite Constellation

"OneWeb - the company building a constellation of satellites to enable global broadband access, has secured $1.2 billion in funding from SoftBank and other existing investors. $1 Billion of the $1.2 Billion will come from SoftBank. This new round of funding will support OneWeb's revolutionary technological development and the construction of the world's first and only high volume satellite production facility. The new facility, based in Exploration Park, Florida will be capable of producing 15 satellites per week at a fraction of the cost ..."

December RF & Microwave Magazine Articles

This latest collection of articles from our industry's magazine publishers include many on radar-related topics. For that matter, I can't think of a topic in electronics that does not have to do with radar. As with most other technologies, radar has become ubiquitous in today's society with applications in everything from automotive traffic monitoring and self-driving systems to security system intruder ...

- Horn and Reflector Antenna Design

    Projects in Words and Pictures

- Metamaterial Advances for Radar

    and Communications

- Scoping a Filter Response with

    Math  <more>

What's All This Power-Supply Design Stuff, Anyway?

Anyone who followed Bob Pease's inestimably insightful series of articles whose titles followed the template "What's All This <subject> Stuff, Anyway?," will have his/her attention immediately grabbed by this piece's title by Paul Rako. Use of the Pease-esque title is for the purpose of providing a segue into one of Bob's pet peeves, not to appropriate the technique. It concerns the [in]validity of building proprietary test equipment rather than using universally available TE to produce repeatable results ...

Woman Trapped in House Due to Wi-Fi and Mobile Phones Allergy

Yep, that's a for-real tinfoil hat she's wearing. Radiation shielding is definitely valid in close proximity to phones and Wi-Fi, but claiming this level of sensitivity is, well, nuts. "Kim De'Atta can rarely see friends and family because electromagnetic waves from modern technology give her migraines, fatigue and even infections. The former nurse has to wear a shielded bed net on the rare occasions she leaves her home and can only visit places with poor mobile phone reception. The debilitating ..." Maybe it's just a cracked dental filling.

Restrictions Proposed for Federal Agencies' 400 Cell-Site Simulators

"The Department of Homeland Security and Justice Department have spent collectively more than $95 million on secret cellphone tracking technology and own more than 400 cell-site simulators that can be used to zero in covertly on the locations of cellphones, according to a congressional report. A report released Monday by the House Oversight and Government Reform Committee reveals a tally of how many cell-site simulators federal agencies own and recommends ..."

Wednesday 21

Please Welcome 3G Shielding Specialties as RF Cafe's Newest Advertiser!

3G Shielding Specialties offers synergistic solutions incorporating metalwork, conductive elements, microwave absorbers and thermal transfer solutions in a single, integrated, turn-key package. Application specific and standard product lines. Design services available. Their three primary areas of focus are waveseal Enclosure Shielding, 3Gmetalworx Board Level Shielding, and wavexorb Microwave Absorbers. Please visit the 3G Shielding Specialties website now to see whether they can help with your work-, school-, or hobby-related project needs.

Pasternack Launches Waveguide Direct Read Attenuators Covering 18 to 110 GHz

Pasternack, a leading provider of RF, microwave and millimeter wave products, has released a new line of waveguide direct read attenuators for instrumentation, test benches, high efficiency RF/Microwave transmissions, SATCOM, MILCOM, radar and telecom applications. Pasternack's direct read attenuators are available in WR-42 to WR-10 waveguide standards operating in seven waveguide bands within

MPATI - Its Problems & Solutions

Although you wouldn't know it from the title, this is actually another of John T. Frye's "Mac's Radio Service Shop" stories. MPATI stands for "Midwest Program on Airborne Television Instruction," and was a pre-satellite-era system for broadcasting educational programming to areas that otherwise did not experience good quality over-the-air reception. DC-6 airplanes were outfitted with a transmitter and a hydraulically stabilized antenna, and would fly for many hours at a time to provide rural areas with classroom instruction via TV. MPATI is a obvious spin-off of the Stratovision system experimented with by Westinghouse Electric ...

Guerrilla RF Intros Failsafe SPDT Switch for Cellular & Satellite Communications

Guerrilla RF Inc., a leading provider of high performance MMICs, today introduces the GRF6011, the first member of the company's growing list of failsafe switch and amplifier devices. Failsafe refers to the characteristic whereby one switch path defaults to a low loss state, when all power is removed. A key application for this single-pole, double-throw (SPDT) switch is at the low noise amplifier (LNA) in a tower mounted amplifier (TMA), where this failsafe functionality is typically

ALPHA Observes Light Spectrum of Antimatter for 1st Time

"In a paper published today in the journal Nature, the ALPHA collaboration reports the first ever measurement on the optical spectrum of an antimatter atom. This achievement features technological developments that open up a completely new era in high-precision antimatter research. It is the result of over 20 years of work by the CERN antimatter community. "Using a laser to observe a transition in antihydrogen and comparing it to hydrogen to see if they obey ..."

Fairview Intros MMBX Connectors and Adapters for PCB Connectivity

Fairview Microwave, a supplier of on-demand microwave and RF components, now offers small form factor MMBX connectors and adapters most commonly used on circuit boards and their associated input/output connections for industrial, telecom and consumer product applications. MMBX-style connectors and adapters are specifically designed to provide versatile and easy PCB-to-PCB connections as well as coax-to-PCB connections. Their mechanical

Tuesday 20

How Christmas Came to S. McSquegg

"The perfect squelch" was a popular concept in the 1950s. I know because I've seen it in a few different magazines from that era. In fact, The Saturday Evening Post ran a regular inset feature by that name. As you might guess, it has t do with making a short statement that has the effect of cutting out the 'noise,' whether it be from the background of a radio reception or from an obnoxious person shooting off his mouth (which was the case for the SEP). BTW, the "Squeg" part of Sunspot McSquegg's name comes from the radio term 'squeg,' which refers to oscillations due to excessive feedback, like what happens when a microphone is ...

Cobham Introduces Two Ultra-Wideband Gooseneck Antennas

Designed for use on Ground Robots, Unmanned Vehicles, Manpacks, Broadcast Cameras and Vehicles, the wideband nature of these antennas allows users to future proof their systems and give increased flexibility when using software defined radios. These antennas can be used to replace several narrow-band antennas reducing a system's 'antenna real estate' which is especially important on manned and unmanned vehicles. Since one antenna can fulfill all needs across multiple bands, Radio suppliers and users can also benefit by reducing

Christmas Song Brought to You by World's Tiniest Radio Receiver

"Physicists at Harvard have built a radio receiver out of building blocks the size of two atoms. It is, almost certainly, the tiniest radio receiver in the world. And since it's a radio, it can play whatever you want to send its way, including Christmas music, as this video by the Harvard team that designed it makes clear: Electrical engineering professor Marko Loncar and graduate student Linbo Shao applied basic radio engineering principles to a very small-scale ..."

NI AWR App Note Discusses Synthesizing UHF RFID Antennas

A new application note featuring NI AWR Design Environment discusses a novel method used for optimizing radio-frequency identification (RFID) antennas and describes two examples of RFID antennas created using this methodology. Because ultra-high-frequency RFID tag antennas need to be inexpensive, efficient, robust for the installation environment, and immune to change in electrical behavior due to proximity to the mounting platform, there

'Gap Filler' GPS Upgrades Advance

"Upgrade and modernization efforts targeting third-generation Global Positioning System (GPS) ground stations are advancing, including a design review milestone for 'gap filler' GPS III operations and upgrades to the current GPS ground control system. Lockheed Martin Corp., which holds several Air Force contracts covering GPS III ground stations along with producing the first ten satellites in the future constellation, said this week it completed a critical design review ..."

Monday 19

CB Radio-Wave Propagation

Raise your hand if you have ever owned a CB radio. Waaaaay back before everyone carried a cellphone, the most common form of unlicensed communication was CB radio. Actually, up through the mid 1970s you were supposed to purchase a license from the FCC, although no test was required as for amateur radio. My first CB was a 23 channel job that I installed in my 1969 Chevy Camaro SS, during my senior year in Southern Senior High School. It was right in the middle of big CB radio craze with CW McCall's "Convoy" song topping the U.S. Billboard charts. My self-appointed 'handle' ...

NuWaves Intros 15 W MMIC-Based C-Band RF Power Amplifier

NuWaves Engineering, an international Radio Frequency (RF) and Microwave solutions provider, announced the upcoming release of the latest offering in the NuPower™ small, lightweight and high-efficiency power amplifier (PA) family of products – the 15 Watt NuPower™ 06C09A C-band PA, which will be available in the second quarter of 2017. The NuPower™ 06C09A will be the first in a series of PA products using NuWaves proprietary GaN-on-SiC microwave monolithic integrated circuit (MMIC) technology

Anatech: No Shortage of Interference Sources in 2016

Anatech Electronics, a manufacturer of RF and microwave filters, has published its December 2016 newsletter. As always, it includes both company news and some tidbits about relevant industry happenings. For this year's end edition, Sam Benzacar discusses the topic of "No Shortage of Interference Sources in 2016," where he takes a look back over the past year at the challenges presented by RF noise issues old and new. Anatech's business is to make certain that system and circuit

EDI CON USA Announces 2017 Event: Save the Date!

EDI CON USA 2017, an event that brings together engineers working on high-frequency analog and high-speed digital designs, will take place at the Hynes Convention Center, September 11-13 in Boston, Massachusetts. Bringing together engineers working in RF / microwave with those working in high-speed digital, EDI CON USA offers an opportunity to learn from other disciplines and transfer techniques and methods between applications. The exhibit floor will include booths

Smoggy Beijing: Orders Factories to Shut or Cut Output

"Beijing's city government ordered 1,200 factories near the Chinese capital, including a major oil refinery run by state oil giant Sinopec, to shut or cut output on Saturday after authorities issued the highest possible air pollution alert. On Friday, China's environmental watchdog issued a five-day warning about choking smog spreading across the north and ordered factories to shut, recommended residents stay ..."

Transistor History Crossword for December 18, 2017

On December 23, 1947, three engineers working at Bell Laboratories demonstrated the world's first semiconductor transistor that produced positive gain. Their names, along with the configuration of their transistor, are buried in the puzzle along with scores of other science and engineering related terms. In fact, every word contained herein has been hand selected by me and there is a money back guarantee if you ever find one not related to mathematics, physics, mechanics, astronomy, chemistry, and all the other sciences. Enjoy! ...

Friday 16

Senior RF Engineer Wanted by Aethercomm

Aethercomm designs and manufactures RF and Microwave amplifier modules, subsystems and systems. The majority of our work is custom. The reliability and effectiveness of thousands of Aethercomm products has been tested and proven in combat, helping to protect and save the lives of our warfighters. Essential duties and responsibilities include simulating, designing, prototyping and testing of RF circuits. Applications include general RF circuits such as LNAs, filters, switches, mixers and power amplifiers, with special emphasis on power amplifiers. Design range in frequency from UHF/VHF to ...

Doodle Labs NTIA Compliant 4.4 GHz NATO Broadband Transceivers

Doodle Labs is excited to announce the availability of the embedded 4.4 GHz NATO Broadband transceivers. The transceivers have been designed to be fully compliant with the NTIA's channel plans for the worldwide deployments. This compliance provides System Integrators with a streamlined path to offer modems and routers for various Military and Public Safety related applications. The 4.4 GHz band, also known as C-Band, is a licensed band dedicated for U.S. and NATO military that offers several

Metamaterials Enable Semiconductor-Free Microelectronics

"Researchers at the University of California San Diego (UCSD) have developed the first optically controlled microelectronic device that doesn't use a semiconductor. The research allows for the design of microelectronic devices that work faster and can handle higher power loads, as well as paves the way for more efficient efficient solar panels, researchers said. Current microelectronic devices, such as transistors, are limited in capability by the properties of components such as semiconductors, which ..."

Sputnik Watch in Erie, Pennsylvania

The Space Race officially began on October 4, 1957, when the USSR successfully launched Sputnik 1, the world's first Earth-orbiting communications satellite. It was a big deal. The 'bird' transmitted a continuous alternate series of pulses at 20.005 MHz and 40.002 MHz, with a 300 ms on and 300 ms off time. The batteries lasted through October 26. Sputnik 1 burned up in the atmosphere on January 4, 1958. Radio monitoring stations all across the Earth scrambled to detect and track Sputnik 1's signals while noting signal strength, frequency stability ...

Navy Strengthens Ship-Based Electronic Warfare

"The service is now in the process of upgrading its existing SLQ-32 Surface Electronic Warfare Improvement Program, or SEWIP - an electronic warfare sensor now on many guided missile cruisers and destroyers. SEWIP is designed to detect approaching threats, such as anti-ship cruise missiles, in time for ship commanders to take defensive or protective actions. It is configured to provide early detection, signal analysis and threat warnings against a range of threats. While much of the work on SEWIP is being done by ..."