Make: Online: Telecommunications Archives

Archive: Telecommunications

November 11, 2009

How-To: Pirate TV

Jon Cohrs writes:

Tired of the blocky, JPEG-like resolution of digital television? Do you long for the days of RF modulation and regulated-yet-unregulated content? Do you simply have the desire to toss your converter box out the window and make use of those rabbit ear antennae that are just lying around? If so, then you might be interested in becoming a savior of analog television! This Instructable will show you how to create your own fully-fledged low-power analog television channel, with any video source(including your computer) as a source of content.

We created one that went live the minute analog tv went dead. We're still the only analog station in NYC, but please join us in making more!!

November 6, 2009

How-To: Make a Star Trek Bluetooth Communicator

Usually I write about ham radio. But looking at communication devices of the future from the past, I thought it would be fun to have a Star Trek: The Original Series Bluetooth communicator for a cellphone. I worked with Dave Clausen to hack one together from a toy Star Trek communicator, a Bluetooth module, and a microcontroller. Following are the directions and program to make your own. And of course a video to show how the Star Trek Bluetooth Communicator works.

And if you really want to geek it up, the Star Trek Bluetooth Communicator can also be used with the Yaesu VX-8R ham radio. It also makes an awesome gift. Read on for the full tutorial.

Read full story

October 27, 2009

How-To: Massive DTV antenna

Instructables user deceiver lives in southern Maine and needed a big DTV antenna to pick up signals from up to 60 miles away, so he build Big Bertha, a giant dtv antenna, and shows your inquiring minds how to do the same.

More:

October 6, 2009

How-To: Set up an HF portable radio while hiking

Fall is the perfect time for hiking, it's not too hot and not too cold. Last weekend I took a day trip to hike up High Mountain in New Jersey and activate SOTA summit W2/NJ008. It's really easy to set up an HF portable radio and not a whole lot to carry up the mountain. This video shows how to get set up including how to hang the antenna in a cluster of trees and making contact with Italy.

September 22, 2009

Sparky Jr, a DIY telepresence robot

We've written about the Sparky Jr. DIY telepresence robot before, however Marque Cornblatt has just launched a new websited dedicated to the project. If you've ever considered building your own telepresence robot, this would be a great place to start. Build instructions and open source software are available on the website.

September 2, 2009

Happy Birthday Hiram Percy Maxim

Today is the 140th birthday of Hiram Percy Maxim the "Father of Organized Amateur Radio." Maxim was founder of the ARRL and a known inventor and tinkerer creating gliders, automobiles, and acoustic silencers. Maxim had 59 patents issued in his name.

The ARRL is hosting a special event in his honor from Sept. 2- Sept. 9.: The operating event is open to all amateurs, and the goal is straightforward: Find the stations adding /140 to their call signs, and contact as many as possible during the event period, September 2-9. Who is eligible to sign /140? ARRL members who hold ARRL appointments, ARRL elected volunteers (such as ARRL Directors and Section Managers), ARRL Life Members, ARRL Headquarters staff and VEs, AECs, QSL bureau workers and awards managers (who are ARRL members). The complete list of eligible positions can be found on page 20 of the September 2009 issue of QST. If you work at least 25 /140 stations, an attractive certificate can be yours! The certificate can be endorsed in increments of 25 QSOs, up to 100.
Time Period: 0000 UTC September 2 until 2400 UTC September 9.

Exchange: All stations signing /140 send RS(T), their appointment and their name; others send RS(T) and their name.

Eligibility: All amateur stations may participate. ARRL Life Members, and those persons holding ARRL appointments, elected positions or ARRL HQ staff, may add /140 to their call signs for the duration of the celebration. Volunteer Examiners, Assistant Emergency Coordinators, QSL Bureau workers, Registered Instructors and Awards Managers who are ARRL members are also invited to participate.

Miscellaneous: /140 stations may be contacted on any band or mode for credit. You can work a station once per band and mode. Repeater contacts are valid for credit, but please be considerate of the users during a repeater's busy periods. All /140 stations are encouraged to be as active as possible on local repeaters and nets. The certificate
is available for making at least 25 contacts with /140 stations, with endorsement increments of 25, and a maximum endorsement of 100. To receive the award, send in a log extract with the date, time, band, call sign worked and exchange for each /140 contact. Include your name, call sign and address, and tell us how many /140 stations you worked. Mail everything to HPM/140 Celebration, c/o W1AW, 225 Main St, Newington, CT 06111-1494. You can also send in your entry on a disk or CD in regular text format. All entries must be accompanied by a check or money order for $5 (US) payable to ARRL. Please make sure your entry is postmarked by October 9, 2009.

August 31, 2009

Ham Radio 101: Getting Started Without a License

There's plenty of fun to be had with ham radio even if you don't have a license. You can get a handheld radio to listen in on what's going on while you are out and about or get a base station/desktop radio. You can listen to activities on local repeaters. Repeaters allow ham radio operators to talk locally, they send a signal to a repeater and it transmits the signal to other radios in the area. You can listen in to their conversations or to Nets, regular ham meet us on repeaters that discuss a certain topic. A larger desktop radio with a longer antenna will also be able to receive amateur HF communications sent directly from ham radios around the world, you can listen to conversations from places like Germany, Kazakhstan, or Japan.

1. Local repeaters can be found by location at this website, tune the frequency of your radio to the output. Even though the repeater is on, it might not be in use meaning that you might not hear anything. You can program several frequencies into your radio, then tune the radio to the different frequencies until you catch a conversation.

2. You can find a schedule of nets and their frequencies on the ARRL website which lists all nets registered with the ARRL. If you have a handheld, select "local nets" and select 2m or 70 cm for the frequency. You will find nets discussing topics ranging from emergency safety (ARES, RACES) to women in ham radio (YL).

3. If your radio can receive HF (high frequency) communications, you can tune around to different stations to listen in. Or you can check DX clusters online which spot operators from rare locations and post their frequency. The call signs of operators from rare locations are listed under "dx". You can mouse-over the call sign to see where the operator is located.

When you are listening in on ham radio, chances are you will hear a lot codes such as 73, cq, qsl, these are abbreviations that were originally used in Morse code and are now used when speaking. You can find a list of them here.

Most ham radios can tune in to frequencies that aren't on the ham bands. At the airport you can listen to air traffic control. In the subway, you can listen to the local transit station and hear what is going on behind the scenes. A lot of handheld radios are waterproof so at the beach you can listen to lifeguard stations or the coast guard. You can listen to Nascar raceways and speedways, zoos, police stations, fire stations, short wave radio, subway and public transportation radios, space shuttle reentry, weather, etc.. All you need is a radio and a guide to the frequencies to tune in to.

1. Local fire department, police department, transit, school safety, sanitation, hospitals, zoos, parks and lifeguards. When you listen to the police stations, you will notice that they use a lot of codes, "we have a 11-24 on Greene and Fort St.". You can learn what those codes mean here.

2. Airport frequencies
Type in the airport code (i.e. JFK) and learn the frequencies for control tower, approaching flights, departing flights, pre-taxi clearance, etc.

3. Nascar raceways and speedways
Free list of frequencies
List of frequencies that you must pay for

4. Local weather

5. Space shuttle frequencies are only transmitted locally. But you can find retransmissions on your local frequencies toward the bottom on the page.

A handheld radio is a really fun thing to bring out with friends to a bar or party. There's always something interesting happening on the radio sure to spur conversation and help you meet new friends. Just program some frequencies into your radio and you will be all set to go. I've found that the police and fire station radios are most exciting to listen to. You can bring earphones and a splitter if you are going to a quieter place like a coffee shop where you might disturb the other patrons.

August 17, 2009

SuitSat: Hacking for Outer space

SuitSat is one of the best examples of fashion hacking and recycling old apparel that I have ever seen. Russia often disposes of space suits by throwing them into outer space to burn up in the atmosphere. The suits take 6-7 months to burn up. Since the suit is already being launched into space, some ham radio operators thought why not house a satellite inside, where it will be protected for 6-7 months before the suit burns up in the atmosphere. Hence SuitSat was born. The first SuitSat was launched into space on September 7, 2006 when astronauts aboard the ISS pushed SuitSat I into space.

Currently, volunteer ham radio operators around the world are working to launch a second SuitSat in Spring 2010. With some recent changes, this homemade satellite won't actually be housed in a discarded space suit. A special structure is being developed to meet new space and safety concerns. Plans are for SuitSat III to be housed in a suit. SuitSat II will transmit on four frequencies:

1. The satellite will send an audio recording broadcasting the name and call sign of the satellite, the telemetry values of the battery, some temperatures, and greetings from children around the world on 2 meter FM (which can be heard with handheld radios and most scanners). With this will also be SSTV still images from onboard cameras.
2. The satellite will broadcast CW (Morse code) signals with the satellite ID, satellite call sign and call signs from people who have contributed to the ARISS program.
3. The satellite will send BPSK data containing full telemetry and data from experiments contributed by universities.
4. The satellite will also have 16 kHz wide transponder (similar to a repeater) with a 70 cm uplink and 2m downlink SSB allowing multiple contacts to be made at the same time (like on other satellites, AO-7, FO-29, and VO-52).

SuitSat II will have an experiment contributed by Kursk State Technical University which measures the vacuum the satellite experiences as it gets increasingly closer to earth. The most exciting part of SuitSat is that future experiment will be contributed by the public - hackers like you! The devices will be powered for 2 minutes each orbit with +5V at a maximum of 100mA. They will be provided 2 seconds to download 2k of data at 9600 bps over an RS-485 link. NASA is developing a process for submitting experiments, so start dreaming up ideas. I know I already have a few in mind.

August 16, 2009

Open source GSM network

800Px-Har2009-Bs11-Antennas
Open source GSM network via /.

...the setup consisted of a pair of BTS' (Base Transceiver Stations) running at 100mW transmit power each and tied to a tree. In turn these provided access to the Base Station Controller (BSC), in this case a Linux server in a tent running OpenBSC. The system authenticated users with a token sent via SMS; in total 391 users subscribed to the service and were able to use their phones as if they were on any other network. Independent researchers are increasingly examining GSM networks and equipment, Welte's work proves that GSM is in the realm of the hackers now and that this realm of mobile networking could be set for a few surprises in the future...

July 22, 2009

Catching satellites on ham radio

My favorite ham activity is making contacts via satellites. Not only is there the romantic notion of sending messages into outer space, but you have to trace the orbit of the satellite with your antenna while tuning the radio, to compensate for the Doppler effect.

The satellites AO-51, SO-50, and AO-27 orbit the Earth acting as repeaters. Repeaters are automated relay stations that allow hams to send signals over a greater distance using low-power hand held transceivers. The satellites allow hams to relay messages from Earth to space and back to other hams somewhere on the planet. The International Space Station (ISS) also has a repeater, but occasionally, if you're lucky, the astronauts turn on their radios to make contact directly with hams on the ground.

The following instructions will get you started listening to birds (satellites) on FM, which can be done with a simple VHF/UHF FM radio with a whip antenna, without the need of a ham license. For better coverage, you can use a Yagi antenna (like the one pictured above) connected to a mutli-mode radio and a license (if you want to transmit). A Yagi antenna can also be used to improve the signal of your hand held radio.

Materials
All you need is a VHF/UHF FM receiver (like a police scanner) or a VHF/UHF transceiver (like a Yaesu VX-7) and an antenna.

1. Specifying your location
Start by visiting Heavens-Above.com to check the orbit of the satellite you want to listen to and specify your location.

2. Specifying a satellite
Check the passes of your specific satellite or the ISS. AO-51, SO-50, AO-27, ISS. Make sure that the passes are shown for your correct location.

3. Reading the chart
This pass chart shows the Start (when/where the satellite enters on the horizon), the Max. Altitude (when/where the satellite is at its highest point in the sky), and the End (when/where the satellite finishes it's pass). Alt. is the altitude, the angle of the satellite from the observer's horizon. 0 degrees is exactly on the horizon, and 90 degrees is directly above the observer. Az. is the Azimuth, the cardinal direction of the satellite from the observer's point of view.

4. Picking a good pass
Satellites orbit the Earth at all sorts of angles, some that are very close to the horizon and some that are directly overhead. It is much easier to hear a satellite that passes directly overhead. To find a good sat pass, check the Max. Altitude Alt. for a pass that is 45 or higher (the higher the better). In our example, the second pass at 7:28 looks like a good one since the Max. Altitude Alt. is 77. The first pass at 5:52 has a Max. Altitude Alt. of only 12 which is very close to the horizon and difficult to pick up.

5. Finding the frequency
Satellite repeaters work with two different frequencies, an uplink and a downlink. You will listen to signals received on the downlink. If you wish to transmit, you'll need to program in the uplink frequency as well. Follow the corresponding links to find the FM repeater frequencies of the satellites. The frequencies often change, so be sure to check the websites for the latest updates. AO-51, SO-50, AO-27, ISS. Tune your radio to the downlink frequency and you're ready to go outside and listen (example: 435.300 MHz FM).

satellitewhipantenna copy.jpg

6. Aiming a whip antenna
If you're using a whip antenna, you will not aim the antenna directly at the satellite. Instead, you'll keep it perpendicular to the satellite. You can rotate the antenna by rotating your wrist to try and get a clearer signal.

7. Following the pass with the antenna
You will trace the path of the satellite orbit with the antenna using the Heavens-Above pass chart as a guide. At the Start Time, start with the antenna perpendicular to the Az. direction at the given Alt. For example, at 7:28, aim the antenna perpendicular to north at 10 degrees above the horizon. Trace the path of the satellite so that at the Max. Altitude Time the antenna is pointed in the corresponding location. For example, at 7:33, the antenna should be perpendicular to west northwest at 77 decrees above the horizon. Finish tracing the path of the satellite so that at the End Time the antenna is perpendicular to the corresponding location. For example at 7:39, the antenna will be perpendicular to south southwest at 10 degrees above the horizon. It can be very difficult trying to catch the satellites and you may spend a lot of time not hearing anything. As you trace the general path of the satellite with the antenna, move the antenna around in small side to side and up and down motions until you hear a bit of audio. Adjust the antenna to make the audio clearer.

8. Tuning the radio for the Doppler effect
The Doppler effect makes the frequency vary by .010 MHz. As you trace the path of the satellite with the antenna, you will also need to tune the radio back and forth plus or minus .010 MHz until you hear a good signal. Early in the pass, you will add .010 MHz, for example, if you're listening on 435.300 MHz, you'll need to tune the radio back and forth between 435.300 MHz and 435.310 MHz. Later in the pass, you will subtract .010 MHz, for example, you will tune the radio back and forth between 435.300 MHz and 435.290 MHz.

Here is an audio clip from my first satellite contacts. The contacts seem to be going pretty slowly, but while I was making them, I remember everything happening very quickly. It was a lot to tune the radio and maneuver the antenna while trying to write down the call signs of the contacts.

June 18, 2009

Ask MAKE: surplus TVs from the DTV switch

Ask MAKE is a weekly column where we answer reader questions, like yours. Write them in to becky@makezine.com or drop us a line on Twitter. We can't wait to tackle your conundrums!

Twitter users @threefourteen, @klaatu, @dcwilson303, @digitalcaffeine, and others all had the same thing on their minds this week and asked "What do we do with all the TVs flooding thrift stores because of the DTV conversion?"

Well, after taking a break to re-watch one of my favorite video art pieces, Media Burn by Ant Farm (above), we've come up with some advice. First off, you can keep your TV in use with a digital receiver, for which you can even make your own antenna. Failing that, you can still watch DVDs on your old set, making them perfect for the movie den, or for donating to your local schools (call and ask if they want them first). Whatever you do, don't throw it in the trash, that old box can contain lots of lead. Recycle it. Now on to repurposing:

Make some art:

get a cheap video camera, make a video loop, and experiment with interference patterns
stack, pile, and create towers of video ala Nam Jun Paik (RIP; pictured above top)
use the TVs as period props for films and plays
make that video installation you've always wanted to
lower its resolution for some pleasing ambiance
burn in some subliminal messages

Take the thing apart:

watch out for the large high-voltage capacitors that can remain charged inside!
teach your kids how cathode ray tubes work
create a video highlighting the "little city" (above)
scavenge it for parts
make a cat bed or fish tank
create a shrine to your favorite cancelled show

Reuse the parts:

make a floating halloween head
convert the old case into a bar
try out the YBOX, an internet appliance for your TV (pictured above)
don't forget your Arduino TV!
try your hand at circuit bending (be extra careful and read up before opening it!)

Have some TV ideas? post them in the comments!

June 13, 2009

The DTV conversion is here!

With the DTV transition upon us, there couldn't be a better time to pick up some coat hangers and some wood and make yourself a kickin' DTV antenna as featured on Make: television. Of course, you'll still need a digital converter box, but here's a simple, low-cost project that can definitely improve your reception. Check out the segment, and then download the PDF for detailed plans on howto make one yourself. Let us know how it works!

Here's the PDF, and be sure to check out more great comments our original blog post.

June 4, 2009

"Eyes-Free" Android interface

The MIT Technology Review website has an article highlighting the work of T.V. Raman and Charles Chen, two Google engineers working on an eyes-free interface for Android called Marvin.

"We are building a user interface that goes over and beyond the screen," says Raman. Often, eyes-free interfaces are employed for blind users, but Raman, who himself is blind, assures that these interfaces have much broader implications. "This is not just about the blind user," he says. "This is about how to use these devices if you're not in a position to look at the machine."

This effort at creating a new interface is in line with the notion of "programs without borders" and is exactly the sort of thing that gets me excited about Android. With a system designed to foster mash-ups, each new component amps up the possibility you'll find the elegant solution you're looking for.

April 26, 2009

G1 PhoneTar

Photo from Connors934 on Flickr

Do you have a phone with a touch screen? Have you tried out some music applications and found the thing a bit awkward to hold? Last year I saw some people messing with guitar application on their phones at the Boston Fab Lab and it got me thinking. When I finally got around to getting a phone, making a PhoneTar was up high on the list of things I 'needed' it for. I did some early testing with the laser cutter for sizing and fit, and the project sat for a while.

When I saw the video of "Kids," the project got reactivated.

Mine is the G1 model of PhoneTar, and though I haven't found many instrument apps for it, I have found that it works fairly well as a stabilizer when taking pictures. It can also work on the dashboard as a way of holding the phone while showing maps, but it would need a way different profile for that.

Want to give it a try? Here is a zip file with the Open Office Draw document I used to cut the part and a pdf of it as well: PhoneTar-G1Tar.zip

To turn it into an iPhoneTar, iTouchTar or possibly a BerryTar wouldn't be too hard, you would need to get measurements of your phone, and change the size and possibly the location of the hole. Different models will have alternate locations for the headphone jack as well.

Looking into the future for the project, I see a need for the right hand to do something. A module down there for strumming or touching contacts would be nice, and could probably be connected to the phone with bluetooth or usb. It would also be nice to have a sound scoop behind the speaker so that it directs the audio towards the audience. A mounted amplifier would be festive as well. It could also be configured for use with the Arduino and Drawdio, both of which can be found in the Maker Shed.

This is not intended to be about a finished project, but rather a step in the Design Process. It does work, but there are many ways it could go from here. My hope is to stir you to action (if you are so inclined) and imagine a new way of seeing your music, phone or other devices. If these ideas gets you thinking, give it a shot and let us know what you come up with!

April 25, 2009

Maker birthdays: Guglielmo Marconi

On this day in way back in 1874 Marchese Guglielmo Marconi was born. At the beginning of the 20th century he played a pivotal role in the development of wireless communication. By incorporating and refining preexisting technologies, Marconi's radiotelegraph sent messages over unprecedented distances. In 1902 his experimental transmissions made it all the way across the atlantic ocean. Marconi's developments most benefitted seagoing vessels of the era - perhaps most famously in 1912 when messages sent from the Titanic's "Marconi room" brought the aid of others. But these historical achievements all trace back to an attic Pontecchio, Italy, where Marconi began his research years before, tinkering and building his own equipment.

The Marconi Collection at the Museum of Science, Oxford documents a variety of equipment produced by the Marconi Co. like the above induction coil. For more info on the man and his life, be sure to visit the relevant entry on Wikipedia.

March 21, 2009

Wearable metadata

Patty Maes of the Fluid Interfaces Group at the MIT Media Lab introduces what may be the must have gadget in the not so far future.

The SixthSense prototype is comprised of a pocket projector, a mirror and a camera. The hardware components are coupled in a pendant like mobile wearable device. Both the projector and the camera are connected to the mobile computing device in the user's pocket. The projector projects visual information enabling surfaces, walls and physical objects around us to be used as interfaces; while the camera recognizes and tracks user's hand gestures and physical objects using computer-vision based techniques. The software program processes the video stream data captured by the camera and tracks the locations of the colored markers (visual tracking fiducials) at the tip of the user's fingers using simple computer-vision techniques. The movements and arrangements of these fiducials are interpreted into gestures that act as interaction instructions for the projected application interfaces. The maximum number of tracked fingers is only constrained by the number of unique fiducials, thus SixthSense also supports multi-touch and multi-user interaction.

Thanks Lyle and Susan.

Want to give this system a try? She says it can be made from off the shelf parts for just $350. Post up your ideas in the comments, and show us your stuff in the MAKE Flickr pool.

Posted by Chris Connors | Mar 21, 2009 08:00 PM
Computers, Culture jamming, DIY Projects, Electronics, Gadgets, hacks, How it's made, Imaging, Something I want to learn to do..., Telecommunications, Virtual Worlds, Wearables, Wireless | Permalink | Comments (7) | Email Entry | Suggest a Site

Wifi robotified rc car

Got an extra router in your parts pile? How about an wifi enabled robotic car?

Wifi Robot: A remote control car that can be driven over the internet or with a laptop wirelessly from up to 500m away. It has a live-feed network camera so that it can be driven without line of sight and a horn so that you can honk at people.

Much to love here, parts libraries, pros and cons about microprocessor chips, oodles of photos, loads of text describing the process and downloadable libaries of files.

via Hack n Mod

What do you think? Let us know in the comments and contribute your photos and video to the MAKE Flickr pool.

March 12, 2009

Story of the Telharmonium

This enjoyably quirky documentary tells the tale of Thaddeus Cahill's Telharmonium, the monstrous forerunner of the analog synthesizer, making music before even the age of popular radio -

The Telharmonium was a 200-ton behemoth that created numerous musical timbres and could flood many rooms with sound.

Beginning with the first instrument, constructed in the 1890's, and continuing with the installation of the second instrument at Telharmonic Hall in New York, the rise and fall of commercial service, the attempted comeback of the third Telharmonium, and ending with efforts to find a home for the only surviving instrument in 1951, this documentary provides a definitive account of the first comprehensive music synthesizer.

It's a shame the video compression is so heavy on this one - though it might be oddly appropriate given the instrument's own technical challenges. Keep in the mind that the accompanying soundtrack is not actually a Telharmonium. Unfortunately no recordings exist of the instrument, though those who did hear it note the clarity of its sinewave voice. [via Oddstrument]

More:

Relay organ plays the sound of switching

February 24, 2009

The ol' Blue Boxing. Good times, good times.

For many of us first-gen hacker types (yes, I'm that old. Shut up.), blue boxing was our introduction to hardware hacking. It was never the illegal, rip-off aspects for me, it was proving that you could build something that exploited a vulnerability in a system; to trick it to do something it wasn't intended to do (the very definition of hacking). In fact, I owe much of my career in tech journalism to phone phreaking. It was a phreak box project in a zine in the mid-90s that inspired me to create my site Street Tech, to cover the burgeoning hardware hacking/DIY electronics scene.

So, I got a huge kick out of seeing this Project MF Blue Box project. It's a site with instructions for creating a classic Blue Box. What good does such an analog phone hacking technology do you in the digital age? Not much (except the box tones are fun to record, store, and play back), unless you call the Project MF server, where they've set up a working simulation of the analog SF/MF signaling used in the public switched telephone networks before the early '90s. Tres retro!

I'm tempted to build this awesome box. It's based on the infamous Blue Box depicted in in 1971 Esquire article on phreaking. This modern version is built around the PIC 12F683 MCU. The folks from Project MF Blue Box gave out free PCBs for this project at Last HOPE, so you may already have the board. They're also selling boards and pre-programmed chips. See the site for details.

The Project MF Blue Box

January 27, 2009

Interactive radio... 1937

Make Pt1679
Listeners Applaud Program Modern Mechanix, 1937 -

BY PRESSING an electric switch, radio listeners may express approval of a current radio program. Holding down a small switch attached to the base of a small lamp placed near the radio, the increased current drain is shown at the local power plant or substation.

Now being used in France, the idea was first tried out by an American power company working with an eastern broadcasting chain.