Category Archives: RF

Tapping into a Ham Radio’s Potential with SDRPlay

Software-defined radios are great tools for the amateur radio operator, allowing visualization of large swaths of spectrum and letting hams quickly home in on faint signals with the click of a mouse. High-end ham radios often have this function built in, but by tapping into the RF stage of a transceiver with an SDR, even budget-conscious hams can enjoy high-end features.

With both a rugged and reliable Yaesu FT-450D and the versatile SDRPlay in his shack, UK ham [Dave (G7IYK)] looked for the best way to link the two devices. Using two separate antennas was possible but inelegant, and switching …read more

Continue reading

Posted in amateur, antenna, FT-450D, ham, Omni-Rig, radio hacks, RF, sdr, sdrplay, spectrum, waterfall, yaesu | Leave a comment

Skin (Effect) in the Game

We love to pretend like our components are perfect. Resistors don’t have capacitance or inductance. Wires conduct electricity perfectly. The reality, though, is far from this. It is easy to realize that wire will have some small resistance. For the kind of wire lengths you usually encounter, ignoring it is acceptable. If you start running lots of wire or you are carrying a lot of current, you might need to worry about it. Really long wires also take some time to get a signal from one end to the other, but you have to have a very long wire to …read more

Continue reading

Posted in ac, Engineering, hackaday 101, Hackaday Columns, radio, RF, skin effect | Leave a comment

Friday Hack Chat: Fundamentals Of RF

Designing a system for communication over RF is a dark art. It’s an obscure domain filled with photonmancy, wires going every which way, and imaginary numbers. RF is reserved entirely for wizards. The guy who simplified Maxwell’s equations into the form we now use went literally insane and replaced all the furniture in his house with granite blocks. This is weird stuff, man.

For this week’s Hack Chat, we’re talking about RF. Everything from the capabilities of different bands, how bandwidth is incorporated into designs, different modulation schemes, RF concepts, I/Q, Nyquist, and other deep-dive topics that elucidate the mysteries …read more

Continue reading

Posted in Hack Chat, Hackaday Columns, RF | Leave a comment

Friday Hack Chat: Energy Harvesting

Think about an Internet-connected device that never needs charging, never plugs into an outlet, and will never run out of power. With just a small solar cell, an Internet of Thing module can run for decades. This is the promise of energy harvesting, and it opens the doors to a lot of interesting questions.

Joining us for this week’s Hack Chat will be [John Tillema], CTO and co-founder of TWTG. They’re working on removing batteries completely from the IoT equation. They have a small device that operates on just 200 lux — the same amount of light that can be …read more

Continue reading

Posted in energy harvesting, Hack Chat, Hackaday Columns, RF, solar | Leave a comment

Doppler Module Teardown Reveals the Weird World of Microwave Electronics

Oscillators with components that aren’t electrically connected to anything? PCB traces that function as passive components based solely on their shape? Slots and holes in the board with specific functions? Welcome to the weird and wonderful world of microwave electronics, brought to you through this teardown and analysis of a Doppler microwave transceiver module.

We’ve always been fascinated by the way conventional electronic rules break down as frequency increases. The Doppler module that [Kerry Wong] chose to pop open, a Microsemi X-band transceiver that goes for about $10 on eBay right now, has vanishingly few components inside. One transistor for …read more

Continue reading

Posted in antenna, Doppler, local oscillator, microwave, mixer, radar, radio, radio hacks, resonator, RF, teardown | Leave a comment

AI Watches You Sleep; Knows When You Dream

If you’ve never been a patient at a sleep laboratory, monitoring a person as they sleep is an involved process of wires, sensors, and discomfort. Seeking a better method, MIT researchers — led by [Dina Katabi] and in collaboration with Massachusetts General Hospital — have developed a device that can non-invasively identify the stages of sleep in a patient.

Approximately the size of a laptop and mounted on a wall near the patient, the device measures the minuscule changes in reflected low-power RF signals. The wireless signals are analyzed by a deep neural-network AI and predicts the various sleep stages …read more

Continue reading

Posted in ai, artificial intellegence, Cycles, misc hacks, mit, non invasive, radio frequency, radio hacks, REM, RF, sleep, sleep monitor, stage, wireless | Leave a comment

Rapidly Prototyping RF Filters

RF filters are really just a handful of strategically placed inductors and capacitors. Yes, you can make a 1 GHz filter out of through-hole components, but the leads on the parts turn into inductors at those frequencies, completely ruining the expected results in a design.

The solution to this is microstrip antennas, or carefully arranged tracks and pads on a PCB. Anyone can build one of these with Eagle or KiCad, but that means waiting for an order from a board house to verify your design. [VK2SEB] has a better idea for prototyping PCB filters: use copper tape on blank …read more

Continue reading

Posted in filter, microstrip, microstrip filter, misc hacks, pcb, radio, RF, rf filter, wireless hacks | Leave a comment

Hackaday Prize Entry: Open Narrowband RF Transceiver

We have so many options when we wish to add wireless control to our devices, as technology has delivered a stream of inexpensive devices and breakout boards for our experimentation. A few dollars will secure you all your wireless needs, it seems almost whatever your chosen frequency or protocol. There is a problem with this boundless availability though, they can often be rather opaque and leave their users only with what their onboard firmware chooses to present.

The Open Narrowband RF Transceiver from [Samuel Žák] promises deliver something more useful to the experimenter: an RF transceiver for the 868 or …read more

Continue reading

Posted in Hackaday Prize, radio, radio hacks, RF, The Hackaday Prize, transceiver | Leave a comment

SDR Sniffing Electric Gates

Most wireless OEM hardware traditionally use 433MHz OOK modules to exchange information. The encoding and encryption of this data stream is left as a task for the embedded software designer. In most cases, the system can be hacked using a replay attack where an RF packet is recorded and replayed to emulate a valid user. [Gilad Fride] hacked his parking gate using this technique but decided to go the extra mile of connecting it to the internet.

He used an RTL-SDR dongle and ook-decoder by [jimstudt] to sniff out the gate code and this code was tested using an Arduino. …read more

Continue reading

Posted in Electric gate, omega, Onion Omega, OOK, RF, sdr, wireless hacks | Leave a comment

Measuring Gait Speed Passively to Diagnose Diseases

You may not realize it, but how fast a person walks is an important indicator of overall health. We all instinctively know that we lag noticeably when a cold or the flu hits, but monitoring gait speed can help diagnose a plethora of chronic diseases and conditions. Wearables like Fitbit would be one way to monitor gait speed, but the Computer Science and Artificial Intelligence Lab at MIT thinks there’s a better way:  a wireless appliance that measures gait speed passively.

CSAIL’s sensor, dubbed WiTrack (PDF), is a wall-mounted plaque that could be easily concealed as a picture or mirror. …read more

Continue reading

Posted in gait, Medical hacks, microwave, motion analysis, Parkinson's disease, RF, speed, velocity | Leave a comment