Spectrum Painting on 2.4 GHz

Give a software-defined radio (SDR) platform to a few thousand geeks, and it’s pretty predictable what will happen: hackers gotta hack. We’re only surprised that it’s happening so soon. Spectrum Painter is one of the first cool hacks to come out of the rad1o badge given out at the CCCamp 2015. It makes it dead-simple to send images in Hellschreiber mode on a few different SDR hardware platforms.

What we especially like about the project is its simplicity. Don’t get us wrong, we’re tremendous fans of GNURadio and the GNURadio Companion software radio hacking environment. But if you just want to do something simple, like send a picture of a smiley-face, the all-capable GNURadio suite is overkill.

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Hackaday Links: May 10, 2015

Here’s a cool crowdfunding campaign that somehow escaped the Hackaday Tip Line. It’s a remote control SpaceShipOne and White Knight. SpaceShipOne is a ducted fan that has the high-drag feathering mechanism, while White Knight is a glider. Very cool, and something we haven’t really seen in the scratchbuilding world.

[Sink] has a Makerbot Digitizer – the Makerbot 3D scanner – and a lot of time on his hands. He printed something, scanned it, printed that scan… you get the picture. It’s a project called Transcription Error.

Keurig has admitted they were wrong to force DRM on consumers for their pod coffee cups.

The Apple ][, The Commodore 64, and the Spectrum. The three kings. Apple will never license their name for retro computer hardware, and there will never be another computer sold under the Commodore label. The Spectrum, though… The Sinclair ZX Spectrum Vega is a direct-to-TV console in the vein of [Jeri Ellisworth]’s C64 joystick doohickey.

Infinity mirrors are simple enough to make; they’re just one mirror, some LEDs, and another piece of glass. How about a 3D infinity mirror? They look really, really cool.

Here’s the six-day notice for some cool events: Hamvention in Dayton, OH. [Greg Charvat] will be there, and [Robert] is offering cold drinks to anyone who mentions Hackaday. If anyone feels like scavenging for me, here’s a thread I created on the Vintage Computer Forum.  Bay Area Maker Faire is next weekend. Most of the rest of the Hackaday crew will be there because we have a meetup on Saturday night

Hackaday Links: May 3, 2015

Everybody loves How It’s Made, right? How about 3D printers? The third greatest thing to come out of Canada featured Lulzbot in their most recent episode. It’s eight minutes of fun, but shame the puns weren’t better. Robertson drives and the Avro Arrow, if you’re wondering.

Speaking of 3D printers, a lot of printers are made of aluminum extrusion. Has anyone tried something like this? It’s an idea that’s been around for a while but we can’t seem to find anyone actually using 3D printed extrusion.

CastARs are shipping out, and someone made a holodeck with retroreflective material. It’s an inflatable dome that’s attached to a regular ‘ol tent that works as a positive pressure airlock. If you’re looking to replicate this, try it with hexagons and pentagons. That should be easier than the orange-slice gores.

For some reason we can’t comprehend, USB ports are now power ports. There’s still a lot of stuff that uses 9 and 12V, and for that there’s the USB 912. It’ll work better with one of those USB battery packs.

Want to see what the Raspberry Pi 2 looks like with a Flir? NOQ2 has you covered.

Remember the Speccy? In the manual, there was an exercise left to the reader: reproduce [Mahler]’s first symphony with the BEEP command. It took a Raspberry Pi (only for synchronizing several Speccys), but it’s finally done.

FCC Creates Innovation Radio, The Future Of Wireless Broadband

Thirty years ago there was a lot of unused spectrum in the 900MHz,  2.4GHz, and 5.2GHz bands. They were licensed for industrial, scientific, and medical uses since their establishment in 1947. But by the 1980s, these bands were identified as being underused. Spectrum is a valuable resource, and in 1985, the FCC first allowed unlicensed, spread spectrum use of these bands. Anyone who has ever configured a router will know the importance of this slice of spectrum: they’re the backbone of WiFi and 4G. If you’re not connected to the Internet through an Ethernet cable, you have the FCC Commissioners and chairpersons in 1985 to thank for that.

Last week, the FCC unanimously voted to allow the use of spectrum in the 3.5GHz band with the Citizens Broadband Radio Service. This opens up 150 MHz of spectrum from 3550 – 3700MHz for new wireless broadband services. If history repeats itself, you will be connecting to the Internet with the Citizens Broadband Radio Service (CBRS) in a few years.

While the April 17th FCC meeting was the formal creation of the CBRS, this is something that has been in the works for a very long time. The band was originally proposed back in 2012 when portions of spectrum were, like the ISM bands back in the 80s, identified as being underused. Right now, the 3.5GHz band is being used for US military radars and aeronautical navigation, but new advances in frequency management as outlined by commissioner [Clyburn] will allow these to coexist with the CBRS. In the words of Chairman [Wheeler], “computer systems can act like spectrum traffic cops.”

Access to the 3.5GHz spectrum will be divided into three levels. The highest tier, incumbent access, will be reserved for the institutions already using it – military radars and aeronautical radio. The second tier, priority access, will be auctioned and licensed by the FCC for broadband providers via Priority Access Licenses (PALs). The final tier, general authorized access, will be available for you and me, provided the spectrum isn’t already allocated to higher tiers. This is an unprecedented development in spectrum allocation and an experiment to see if this type of spectrum allocation leads to more utilization.

There are, however, unanswered questions. Commissioner [O’Rielly] has said the three-year license with no renewable expectancy could limit commercial uptake of PALs. Some commentors have claimed the protocols necessary for the CBRS to coexist with WiFi devices does not exist.

Still, the drumbeat demanding more and more spectrum marches on, and 2/3rds of the 150MHz made available under this order was previously locked up for the exclusive use of the Defense Department. Sharing spectrum between various users is the future, and in this case has the nice bonus of creating a free citizens band radio service.

You can read the full order here, or watch the stream of the April 17th meeting.

Sine Waves, Squares Waves, and the Occasional FFT

I became aware of harmonics and the sound of different shaped waveforms early in my electronics career (mid 1970’s) as I was an avid fan of [Emerson Lake and Palmer], [Pink Floyd], [Yes], and the list goes on. I knew every note of [Karn Evil 9] and could hear the sweeping filters and the fundamental wave shapes underneath it.

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I remember coming to the understanding that a square wave, which is a collection of fundamental and (odd) harmonics frequencies, could then be used to give an indication of frequency response. If the high frequencies were missing the sharp edges of the square wave would round off. The opposite was then true, if the low frequencies were missing the square wave couldn’t “hold” its value and the top plateau would start to sag.

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HOPE X: Citizens Band Microwave Spectrum And Free Internet For All

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The bulk of HOPE X was the talks, but arguably the far more interesting aspect of thousands of hackers and tinkerers under one roof is talking to everyone about what they’re doing. One guy hanging out at HOPE gave a quick lightning talk to a few people about something very interesting: something the FCC is pushing through that’s open to just about everything: it’s the FCC’s new CB radio service (you’ll want to click the presentation link at the very top of the page), giving anyone, not just people with a radio license, access to a huge swath of microwave spectrum.

The short version of the talk was the fact the FCC is extremely interested in opening up 100 to 200 MHz of spectrum at 3.5 GHz. The idea is to create something like cellular service that can either be implemented by companies, or normal, everyday people. The initial goal of this is to provide -possibly- free Internet to anyone with the right USB dongle. Since it’s just radio, and open to everyone, just about anything can be implemented.

This is something the FCC, Google, Microsoft, and a whole bunch of startups are extremely interested in, and the fact that about half of the spectrum will be open to anyone creates some interesting opportunities. A community-based freenet of wireless Internet links becomes an easy solution, and since the hardware to access 3.5 GHz is similar to other hardware that’s already available means building your own wireless ISP could be relatively easy in 12 to 18 months.

A transcript of the lightning talk is available below.

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The HellZXchreiber

HellZXschreiber

Hellschreiber – German for ‘light pen’ – was developed in the 20s as a way to transmit text in a way that was much more robust than the teletypes of the time. These devices were used to great effect by the Germans in WWII, and later became popular with wire services and was used until the 80s. The fax machine then happened, and no one really cared about Hellschreiber, save for a few plucky amateur radio enthusiasts.

In the early 90s, a few of these amateur radio enthusiasts realized they could use their personal computers to communicate with this extremely simple protocol that’s also very resilient against interference and weak radio links. [Danjovic] is following in their footsteps by decoding Hellschreiber on an old ZX Spectrum clone.

[Danjovic] tested his code with the sound sample found in the Hallschreiber wiki article and some text generated by Fldigi. Everything works beautifully, an [Dan] can even change the intensity of the text with the volume control – a very useful feature should the HellZXchreiber ever make it out into the field.

Source and image files available for all you strange Speccy fans. Everyone else can check out the videos below.

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