RF Cafe Software
About RF Cafe
1996 - 2022
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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The inventions and products featured on these pages were chosen either for their uniqueness in the RF engineering realm, or are simply awesome (or ridiculous) enough to warrant an appearance.
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we are on the subject of cellphone performance enhancing devices, these two femtocells take the
miniature cell tower form factor from a 2" cube (see
cubes), down to that of a USB stick in the case of PicoChip, and a small cell phone in the case of
Ubiquisys. Both use a nearby wireless Internet connection to relay the signal between your cellphone and the
tower. By doing so, international roaming charges are avoided. PicoChip's dongle is contry-specific, but
Ubiquisys' slightly larger femtocell can figure out what country it is in and configure its broadcast to
comply with local spectrum usage regulations. In some cases, the allowable power is so low that the phone
needs to be placed on top of it. In Japan, law requires a licensed engineer to accompany the installation and
configuration of every cell tower - no matter the size - so neither of these devices are legal there.
For some reason this just struck me as kind of funny. There have been a lot of headlines recently about the military adopting smartphones as part of the battlefield stratagem. Here is an iPhone app that helps train soldiers how to fire Patriot Missiles. C² Technologies says this is the first segment in a series of seven iPhone mobile applications the company is developing to train Patriot Missile crews for the U.S. Army. Eventually, the apps will train in launch station, radar maintenance, antenna mast group, electrical power plant, and missile reload march order and emplacement. I'm betting the CIA has embedded code to execute an actual launch.
I seem to be on a book theme this week, so here is another one for you. In spite of, or maybe because of, the overwhelming amount of e-books and e-readers and e-everything else, something of a renaissance is underway for printed material. Fortunately for the buyer, prices are low. That includes the option to publish your own book, even a hard cover version, for not much money. Inc magazine featured a company called blurb, which will bind and print any quantity (including just one) for you at a price along the lines of with what you might pay at Amazon.com or Barnes and Noble. A standard size book (8x10") with up to 160 pages costs $50 for just one. Volume pricing is offered for quantities >10. Lulu is another option among many.
was launched by AMSAT-UK to foster interest in school kids for space, physics, electronics, and radio. The
transponder uplink is 435.080 – 435.060 MHz, and the downlink is 145.960 – 145.980 MHz with beacons on 145.955
MHz CW and BPSK. In order to facilitate participation, a software defined radio device has been designed - the
FUNcube Dongle. It can be tuned anywhere from
64-1,700 MHz, with a BW of up to 80 kHz. Since it is SDR, any modulation scheme that fits within 80 kHz is
doable. There are two versions. The Base model is frequency restricted and designed as an entry level minimal
cost device, targeted for educational outreach. The Pro model is unrestricted in its frequency coverage. Only
the Pro model is currently available, at a cost of £99 ($162) + 20% VAT (EC only) and shipping. There are PCB
and spectrum images on the website.
What do vintage grain mills, your lawn sprinkler, and Hoover Dam have in common with Ecodigital's new H2O FM radio? They all run on water power. According to their website, the H2O is the world's first water pressure powered shower radio. It is installed inline between the shower supply pipe and the shower head. The water flow powers a patented, integrated turbine generator which creates energy to power the radio. The H2O Shower Power Radio is a patented innovative product which uses the latest technology of miniature water turbines to create energy. A built-in rechargeable battery allows you to take the radio with you for listening elsewhere - maybe in a good rain downpour!
Mudflaps -- They're not just for stopping rocks and mud anymore. That's right, why bother even having a mudflap if it can't double as an antenna? GreenWave Scientific must have asked that question when developing a method for embedding an antenna in otherwise ordinary mudflaps. Their Mudflap Antennas operate in the VHF/UHF bands, covering 20-500 MHz. "The antenna consists of a radiating element embedded in industrial grade rubber forming a mudflap antenna for retrofit installation on numerous military and commercial truck types. Various installation and mounting hardware options are available." Its stealthy form factor keeps it from advertising your radio equipment to lurking thieves, and provides RF coverage equivalent to a roof mounted whip. Trick up your semi or F-250 today!
Explorer is billed by designer Ariel Rocholl as, "an affordable handheld spectrum analyzer designed from
scratch to be a sort of Swiss army knife for the specific needs of ISM band digital communication." Depending
on which module you use (433, 868, 915 MHz or 2.4 GHz), RF Explorer will detect and measure the power using
the spectrum analyzer mode (peak max, normal and averaging modes ) for signals from -110 to 0 dBm, or use it
as an RF generator with a 0 to +10 dBm output. Resolution BW adujsts automatically for 2.6 to 80 kHz. A
backlit LCD is provided, or use the miniUSB port to connect to a PC and get higher resolution. Up to 5 screen
shots can be stored. RF Explorer is 113x70x25 mm and weighs just 185 g. The price is $95 USD.
Ewww... Who would want a cellphone shaped like this? Elfoid is a miniature anthropomorphic robot-shaped phone that "is designed to transmit not only voice but also 'human presence.'" It registers your own body motion and voice tones with motion sensors, a camera, and microphone to cause the blob to react similarly. I don't know if it cries when you are sad, but maybe at least the butt cheeks clench (see video) when it detects that you are in a threatening situation (did I just write that?). Elfoid was developed by famous Japanese roboticist Hiroshi Ishiguro, the guy who builds incredibly life-like robots that look like himself. Creepy.
Just as in the PC world the quality and sophistication of software applets evolved over time from crude, text-based user interfaces and zero input error checking, apps for smartphones have improved considerably since early versions. Even relatively simple functions are now enhanced with increased options and helpful graphical interfaces. The resistor identifier app shown here not only presents a realistic looking component, but also allows the user to cursor over the bands to either read off values or the change the colors. Another app lets you enter digital inputs to common logic gates and see the result at the output. Need resonant frequency for an LC tank circuit? There's an app for that. Agilent has a nice RF coupler parameter calculator. Most cost no more than a new ring tone.
matter what the cost, those evil Edison light bulbs will be banished from the face of the Earth. Even if we
have to replace harmless tungsten with a highly toxic element like mercury
(which incidentally we removed from light switches 50 years ago because it causes brain damage) then by
Jupiter that's what we'll do. Even if the energy used to produce, package, distribute, and then properly
dispose of the Hg-filled CFL bulbs proves to be greater than with Edison's invention, they simply must go.
Even if to make CFLs acceptable we have to add complexity like imbedding a halogen bulb in the middle of a CFL
(packaged so that it looks like an incandescent bulb) to make it
bright when first switched on and then turn off after the CFL warms up, we'll do that, too. Silly, you say? GE
has done so with their new Energy Smart Soft White bulb. Can you imagine what it cost to design and produce
the circuit and components for that beast? Suggest name for the bulb: The Rube Goldberg. Expected
sale price will be $6-$10 each.
Alcatel-Lucent has developed a LightRadio cube that allows a distributed approach to cell phone towers. These Rubik's Cube-sized devices reportedly perform all the functions of a cell tower at a small fraction of the power requirement. The idea is to locate the cubes anywhere and everywhere - bus stops, coffee shops, malls, schools, sports stadiums. Smart software allows the cubes to coordinate communications between themselves and the distant towers. Lower radiated power levels in both directions is one of the benefits, along with offloading data congestion from towers. LightRadios can even be configured in arrays that form steerable phased arrays so that power can be directed toward users. It's a slick idea. The problem I see is an opportunity for some nefarious person - or government - to replace cubes with look-alikes that hijack data and maybe embed Trojans into users' phones.
Technology often melds many disciplines to service nearly every aspect of life. Hobby and sports gear are rarely anymore a simple application of raw materials and baseline technology. The iBike Dash cycling computer is a prime example of one high tech device leveraging capabilities of another. A wireless link with your iPhone allows the Dash to combine GPS and communications functions from the phone with its own software to perform a pretty amazing set of calculations and displays. For instance, using optional heart rate and cadence sensors, it can calculate the rider's power output in calories based on GPS position and elevation change data. Recall that fundamentally work = force x distance, and calories are units of work. The Dash will also display a moving route map, weather map, and much more. Of course, this kind of technology sharing has been around a long time. Who among us in the 1970s didn't own one of those cassette adapters that plugged into your 8-track player? I swear, though, that I never did disco!