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Archive for the ‘radio hacks’ Category

Students from the Indian Institute of Science Education and Research combined a commercial satellite dish, a satellite finder and an Arduino, and produced a workable radio telescope. The satellite dish provides the LNB (low noise block) and the associated set-top box is used only for power.  Their LNB employs an aluminum foil shield to block extraneous signals.

In addition to the hardware, the team built Python software to analyze the data and show several practical applications. They used known geostationary satellites to calibrate the signal from the finder (digitized by the Arduino) to determine power per unit voltage. They also calculated the beam width (about 3.4 degrees) and used the sun for other calibration steps.

The paper notes that some designs use the ubiquitous RTL-SDR, but this limits the bandwidth to about 3 MHz. The satellite finder detector is inherently broadband and the team claims a bandwidth for their scope of 1.1 GHz. Some designs (like the Itty Bitty) use a dual LNB to have both. If you are too lazy to build any hardware, you can still get into the radio telescope data crunching game.

If you want an introduction to radio astronomy, you might enjoy Dr. John Morgan’s lecture, in the video below.


Filed under: Arduino Hacks, radio hacks

There’s an old saying that the nice thing about standards is there are so many of them. For digital voice modes, hams have choices of D-Star, DMR, System Fusion, and others. An open source project, the Multimode Digital Voice Modem (MMDVM), allows you to use multiple modes with one set of hardware.

There are some kits available, but [flo_0_] couldn’t wait for his order to arrive. So he built his own version without using a PCB. Since it is a relatively complex circuit for perf board, [flo_0_] used Blackboard to plan the build before heating up a soldering iron. You can see the MMDVM in action below.

The build includes an Arduino, of course, and the neat perf board wiring makes for a good-looking project. We’ve covered digital voice that uses PCs before and even some digital ham modes that use an Arduino. Or check out the MMDVM project for more info.


Filed under: Arduino Hacks, radio hacks

[Tom Hall], along with many hams around the world, have been hacking the Silicon Labs Si5351 to create VFOs (variable frequency oscillators) to control receivers and transmitters. You can see the results of his work in a video after the break.

vfo board[Tom] used a Teensy 3.1 Arduino compatible board, to control the Si5351 mounted on an Adafruit breakout board. An LCD display shows the current frequency and provides a simple interface display for changing the output. A dial encoder allows for direct adjustment of the frequency. The ham frequency band and the frequency increment for each encoder step are controlled by a joystick. When you get into the 10 meter band you definitely want to be able to jump by kHz increments, at least, since the band ranges from 28 mHz to 29.7 mHz.

So what is the Si5351? The data sheets calls it an I2C-Programmable Any-Frequency CMOS Clock Generator + VCXO. Phew! Let’s break that down a bit. The chip can be controlled from a microprocessor over an I2C bus. The purpose of the chip is to generate clock outputs from 8 kHz to 160 kHz. Not quite any frequency but a pretty good range. The VCXO means voltage controlled crystal oscillator. The crystal is 25 mHz and provides a very stable frequency source for the chip. In addition, the Si5351 will generate three separate clock outputs.

[Tom] walks through the code for his VFO and provides it via GitHub. An interesting project with a lot of the details explained for someone who wants to do their own hacks. His work is based on work done by others that we’ve published before, which is what hacking is all about.


Filed under: Arduino Hacks, radio hacks

[jmilldrum] really gets a lot of use out of his Si5351A breakout board. He’s a ham [NT7S], and the Si5351A can generate multiple square waves ranging from 8 kHz to 160 MHz, so it only stands to reason that it is going to be a useful tool for any RF hacker. His most recent exploit is to use the I2C-controllable chip to implement a Fast Simple QSO (FSQ) beacon with an Arduino.

FSQ is a relatively new digital mode that uses a form of low rate FSK to send text and images in a way that is robust under difficult RF propagation. There are 32 different tones used for symbols so common characters only require a single tone. No character takes more than two tones.

The Si5351A can easily handle the encoding job. Since the output is a square wave, you do need a low-pass filter to put it on the air. [jmilldrum] also used some relatively small amplifiers to get the output up to 20 watts.

You might remember, we’ve talked about [jmilldrum’s] work with the Si5351A before. We also recently were talking about hams experimenting with digital modes and this is a great example, both by the developers of FSQ and [jmilldrum] for implementing it with an Arduino. If you want to learn more about FSQ, see the video below.


Filed under: Arduino Hacks, radio hacks, wireless hacks

When you have an older vehicle there’s not a lot of options in the stock stereo department, often a CD player and tape deck is what you get. When you want to play your tunes from your mobile what do you do? Buying an adapter, or a new head unit for that matter, isn’t any fun. So why not hack it? This isn’t just a mechanical marriage of a Bluetooth dongle and an elderly stereo. Some real work went into convincing the stereo that the BT receiver was the stock tape deck.

car-stereo-logic-analyzerAttacking the outdated Cassette deck [kolonelkadat] knew that inside the maze of gears and leavers, most of it is moving around actuating switches to let the radio know that there is a tape inside and that it can switch to that input and play. Tricking the radio into thinking there is a tape inserted is handled by an Arduino. Using a logic analyzer [kolonelkadat] figured out what logic signals the original unit put out and replicating that in his Arduino code.

Audio is handled by the guts of a bluetooth speaker with the output redirected into the radio where the signal coming off the tape head normally would have been directed. Join us after the break for a couple of videos with all of the details.


Filed under: Arduino Hacks, musical hacks, radio hacks
Ago
06

$40 Antenna Analyzer with Arduino and AD9850

ad9850, Amateur Radio, antenna analyzer, arduino hacks, dds, ham radio, radio hacks Commenti disabilitati su $40 Antenna Analyzer with Arduino and AD9850 

If you are a hacker, you might consider ham radio operators as innovative. Most people, however, just see them as cheap. So it is no surprise that hams like [jmharvey] will build an antenna analyzer from a DDS module and an Arduino instead of dropping a few hundred dollars on a commercial unit. As he points out, you probably only need an analyzer for a day or two while you set up an antenna. Unless you are a big time antenna builder, the unit will then sit idle on the shelf (or will wind up on loan to hams even cheaper than you are).

The design is rooted in another proven design, but changed to take advantage of parts he happened to have on hand. Although the build is on a universal circuit board, [jmharvey] used Eagle to lay out the circuit as though it were a PCB. Since placement can be important with an RF circuit, this isn’t a bad idea. It’s always easier to move stuff around on the screen than on the perf board.

Since this is a no frills, unit, you are expected to grab the output from the Arduino and manually put it in a spreadsheet to plot the results. There is another version of the Arduino code that drives an OLED screen, although you still need a PC to kick the process off. One interesting feature of the Arduino code is how it deals with the nonlinear nature of the diodes used in the circuit. After plotting the values with known loads, [jmharvey] broke the diode operation into three regions and used different equations for each region. Even so, he warns that readings higher than 1:1 VSWR are only accurate to 10% or 20% – still good enough for ham shack use.

If you want an antenna analyzer for $40 (or less, if you have a good stock of parts) this looks like a worthwhile project. If, however, you want to repurpose it to Rickroll your neighbor’s AM radio, you might want to go with the commercial unit.

Click past the break to see the analyzer in action.


Filed under: Arduino Hacks, radio hacks
Lug
14

HamShield Puts Your Arduino On The Radio

Amateur Radio, arduino, arduino hacks, arps, ham radio, hamshield, packet radio, radio hacks, shield, transceiver Commenti disabilitati su HamShield Puts Your Arduino On The Radio 

Anybody can grab a USB TV tuner card and start monitoring the airwaves, but to get into the real meat of radio you’ll need your amateur radio license. Once you have that, the bandwidth really opens up… if you can afford the equipment. However, [spaceneedle] and friends have dramatically lowered the costs while increasing the possibilities of owning a radio by creating this ham radio shield for the Arduino.

The HamShield, is a versatile shield for any standard Arduino that allows it to function like an off-the-shelf radio would, but with a virtually unlimited number of functions. Anything that could be imagined can be programmed into the Arduino for use over the air, including voice and packet applications. The project’s sandbox already includes things like setting up mesh networks, communicating over APRS, setting up repeaters or beacons, monitoring weather stations, and a whole host of other ham radio applications.

HamShield operates on a wide range of frequencies and only uses a 250 mW amplifier. The power draw is small enough that the HamShield team operated it from a small solar panel, making it ideal for people in remote areas. The project is currently gathering funding and has surpassed their goal on Kickstarter, branding itself appropriately as the swiss army of amateur radio. The transceiver seems to be very robust, meaning that the only thing standing in the way of using this tool is simply writing the Arduino code for whatever project you want to do, whether that’s as a police scanner or even just a frequency counter. And if you want to follow along on hackaday.io, the project can be found here.


Filed under: Arduino Hacks, radio hacks
Dic
11

Over-engineering Ding Dong Ditch

arduino, arduino hacks, ask, doorbell, gsm, OOK, radio, radio hacks, RTL-SDR Commenti disabilitati su Over-engineering Ding Dong Ditch 

One day, [Samy]’s best friend [Matt] mentioned he had a wireless doorbell. Astonishing. Even more amazing is the fact that anyone can buy a software defined radio for $20, a small radio module from eBay for $4, and a GSM breakout board for $40. Connect these pieces together, and you have a device that can ring [Matt]’s doorbell from anywhere on the planet. Yes, it’s the ultimate over-engineered ding dong ditch, and a great example of how far you can take practical jokes if you know which end of a soldering iron to pick up.

Simply knowing [Matt] has a wireless doorbell is not enough; [Samy] needed to know the frequency, the modulation scheme, and what the doorbell was sending. Some of this information can be found by looking up the FCC ID, but [Samy] found a better way. When [Matt] was out of his house, [Samy] simply rang the doorbell a bunch of times while looking at the waterfall plot with an RTL-SDR TV tuner. There are a few common frequencies tiny, cheap remote controls will commonly use – 315 MHz, 433 MHz, and 900 MHz. Eventually, [Samy] found the frequency the doorbell was transmitting at – 433.8 MHz.

After capturing the radio signal from the doorbell, [Samy] looked at the audio waveform in Audacity. It looked like this doorbell used On-Off Keying, or just turning the radio on for a binary ‘1’ and off for a binary ‘0’. In Audacity, everything the doorbell transmits becomes crystal clear, and with a $4 434 MHz transmitter from SparkFun, [Samy] can replicate the output of the doorbell.

For the rest of the build, [Samy] is using a mini GSM cellular breakout board from Adafruit. This module listens for any text message containing the word ‘doorbell’ and sends a signal to an Arduino. The Arduino then sends out the doorbell code with the transmitter. It’s evil, and extraordinarily over-engineered.

Right now, the ding dong ditch project is set up somewhere across the street from [Matt]’s house. The device reportedly works great, and hopefully hasn’t been abused too much. Video below.


Filed under: Arduino Hacks, radio hacks
Ott
12

Build Your Own Stand Alone Web Radio

arduino, arduino hacks, internet radio, radio hacks, web radio channel, web radio player Commenti disabilitati su Build Your Own Stand Alone Web Radio 

Arduino-based web radio
If you’re the type who enjoys passing idle time by keeping up with podcasts or listening to web stations but don’t always want to occupy your laptop or tablet, this Arduino based radio player will provide a base station for tunes.

The Web Radio project by [Vassilis Serasidis] outlines in a pleasing amount of detail exactly how to wire up a short list of four modules. These including an Ethernet shield, LCD screen, MP3 decoder, and USB serial converter, with an Arduino Mini in order to bookmark and play fourteen of your favorite channels. His hand-soldered board couples everything into one neatly stacked package. The instructional video shows this off and he even explains how to locate your favorite stations on internet-radio.com and copy their port and IP number directly into an example sketch which is provided for use. If you’ve been wanting to build a self contained radio node for your desk free of extra baggage, this is a no-sweat project for both the hardware savvy and those more oriented with code writing.

If you’re going to build your own radio, it’s always cool to disguise your high-tech creation as something more rustic. Check out this project by [Dominic Buchstaller] for a great example of a vintage radio given a second calling.

 


Filed under: Arduino Hacks, radio hacks
Ott
01

Strobe Remote

If you want to take a photograph with a professional look, proper lighting is going to be critical. [Richard] has been using a commercial lighting solution in his studio. His Lencarta UltraPro 300 studio strobes provide adequate lighting and also have the ability to have various settings adjusted remotely. A single remote can control different lights setting each to its own parameters. [Richard] likes to automate as much as possible in his studio, so he thought that maybe he would be able to reverse engineer the remote control so he can more easily control his lighting.

[Richard] started by opening up the remote and taking a look at the radio circuitry. He discovered the circuit uses a nRF24L01+ chip. He had previously picked up a couple of these on eBay, so his first thought was to just promiscuously snoop on the communications over the air. Unfortunately the chips can only listen in on up to six addresses at a time, and with a 40-bit address, this approach may have taken a while.

Not one to give up easily, [Richard] chose a new method of attack. First, he knew that the radio chip communicates to a master microcontroller via SPI. Second, he knew that the radio chip had no built-in memory. Therefore, the microcontroller must save the address in its own memory and then send it to the radio chip via the SPI bus. [Richard] figured if he could snoop on the SPI bus, he could find the address of the remote. With that information, he would be able to build another radio circuit to listen in over the air.

Using an Open Logic Sniffer, [Richard] was able to capture some of the SPI communications. Then, using the datasheet as a reference, he was able to isolate the communications that stored information int the radio chip’s address register. This same technique was used to decipher the radio channel. There was a bit more trial and error involved, as [Richard] later discovered that there were a few other important registers. He also discovered that the remote changed the address when actually transmitting data, so he had to update his receiver code to reflect this.

The receiver was built using another nRF24L01+ chip and an Arduino. Once the address and other registers were configured properly, [Richard's] custom radio was able to pick up the radio commands being sent from the lighting remote. All [Richard] had to do at this point was press each button and record the communications data which resulted. The Arduino code for the receiver is available on the project page.

[Richard] took it an extra step and wrote his own library to talk to the flashes. He has made his library available on github for anyone who is interested.


Filed under: Arduino Hacks, radio hacks


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