Retrotechtacular: Fundamentals of AM and FM Radio Communication

AM Transmitter

How radios send and receive information can seem magical to the uninformed. For some people, this week’s Retrotechtacular video, “Frequency Modulation – Part 1 Basic Principles”, from the US Army Department of Defense 1964 will be a great refresher, and for others it will be their first introduction into the wonderful world of radio communications.

The stated objective is to teach why FM radio communication reduces interference which normally afflicts AM radio communications. Fundamentals of AM and FM is a better description, however, because the first part of the video nicely teaches the principles of AM and FM radio communications. It isn’t until later in the clip that it delves into interference, advantages of FM modulation, and detailed functioning of FM radio. The delivery is slow at times and admittedly long, yet the pace is perfect for a young ham to follow along with plenty of time to soak in the knowledge. If you’re still on the fence about becoming a ham here’s some words or encouragement.

Though the video isn’t aimed at ham radio users it does address core knowledge needed by amateur radio hobbyists. Amateur radio is full of many exciting communication technologies and you should have a clear understanding of AM and FM communication methodologies before getting on Grandpa’s information super highway. Once you have your ham license (aka ticket) you have privileges to create and test amazing ham related hacks, like [Lior] implementing full programmable control of a Baofeng UV5R ham radio using an Arduino.

Join us after the break to watch the video.

[Read more...]

Guest Rant: Ham Radio — Hackers’ Paradise


Editor’s Note: This is a guest post written by [Bill Meara]

The suits at Hack-a-Day reached out to SolderSmoke HQ and asked me to send in a few words about why their readers should take a fresh look at ham radio. Here goes:

First, realize that today’s ham radio represents a tremendous opportunity for technical exploration and adventure. How about building a station (and software) that will allow you to communicate by bouncing digital signals off the moon? How about developing a new modulation scheme to send packets not down the fiber optic network, but around the world via the ionosphere, or via ham radio’s fleet of satellites? How about bouncing your packets off the trails left by meteors? This is not your grandfather’s ham radio.

You can meet some amazing people in this hobby: Using a very hacked-together radio station (my antenna was made from scrap lumber and copper refrigerator tubing) I’ve spoken to astronaut hams on space stations. Our “low power, slow signal” group includes a ham named Joe Taylor. Joe is a radio astronomer who won the Nobel Prize for Physics. He’s now putting his software skills to use in the development of below-the-noise receiving systems for ham radio. Join me after the break for more on the topic. [Read more...]

Turning an easter egg hunt into a fox hunt


We’ve seen [Todd Harrison]‘s work a few times before, but he’s never involved his son so throughly before. This past Easter, he thought it would be a good idea for his son and a few of his friends to take part in an easter egg hunt. Being the ham he is, he decided to turn an easter egg hunt into an adventure in radio direction finding, or as amateur radio operators call it, a fox hunt.

[Todd] put together a great tutorial on building a yagi – a simple directional antenna – out of a couple of pieces of PVC pipe and a few aluminum and brass rods. With this and a handheld ham set, [Todd] hid a fox along with a stuffed easter bunny and a basket of candy near a local park. Operating under the guidance of his dad, [Todd]‘s son and his friends were eventually able to find the fox. Leaving candy out in the Arizona sun probably wasn’t [Todd]‘s best idea – the fox, and candy, were covered in ants when they were found – but it was a great introduction to amateur radio.

Writing new firmware for a handheld radio


When playing around with a cheap, handheld, dual-band radio, [Lior], a.k.a. [KK6BWA], found a schematic for a similar and even cheaper radio. He realized the programming pads were very accessible and the dev tools for the radio’s microcontroller were available from the manufacturer. After these discoveries, there really was only one thing to do: write new firmware for a $40 radio, and making a great tool for playing around in the 2 meter and 70 cm bands.

The instructions for reflashing the firmware on this radio only require an Arduino and a handful of miscellaneous components. [Lior]‘s new firmware for the uv3r radio isn’t quite finished yet, but he plans on adding some really impressive features. Things like a better UI for a four-button radio, a mode for tracking satellites, a digital mode, and a computer-controlled mode are all possible and on [Lior]‘s project wishlist.

Getting a $40 radio to do your bidding with an Arduino is cool enough, but [Lior] says this mod for the uv3r can be taken even further: if you’ve got an amateur radio license, it’s possible to use the uv3r to control an Arduino or other microcontroller from miles away. It’s a great hack, right up there with the USB TV tuner/software defined radio thing we saw almost exactly one year ago.

You can check out a demo of some custom software running on the uv3r after the break. The radio listens for a DTMF tone (supplied by the uv3r’s big brother, the uv5r), and plays back a three-digit DTMF tone. There’s also a more through walk through of what [Lior]‘s new radio can do as well.

[Read more...]

Amateur radio field day is upon us

Looking for something to do this fine Saturday morning? For the US and Canadian readers out there, the fourth weekend in June is amateur radio field day, a day when all the amateur radio and ham geeks get together, string up a few antennas, and do their yearly community outreach/contact as many other radio heads as possible.

This weekend, there are more than 1600 field day events taking place all across the US and Canada. Odds are, you’re not more than a half hour drive from a field day event; you can find the closest one with the AARL’s handy Google Map of field day locations.

Since last year, we’ve seen a whole host of cool stuff to do with radio including a $20 software defined radio. If getting your license is too big of a step for you right now, you could at least plug a USB TV tuner dongle into your computer and see what is possible with radio. As a neat little bonus, you don’t even need a license for SDR. You might need a better antenna, and the ham guys at field day will be more than happy to point you into the right direction.

Hellduino: Hellschreiber radio transmissions from an Arduino board

[Mark VandeWettering] was experimenting with a simple transmitting circuit and an Arduino. The circuit in the project was designed by [Steve Weber] to broadcast temperature and telemetry data using Morse Code. But [Mark] wanted to step beyond that protocol and set out to write a sketch that broadcasts using the Hellschreiber protocol.

This protocol transmits glyph images, which are decoded as you see above. For some reason we can’t help but think this is like Captcha for radio enthusiasts. We have seen Hellschreiber used with AVR microcontrollers before, but this is the first Arduino implementation that we’ve come across. [Mark] does a great job of demonstrating his project in the video after the break. He mentions that the transmitter has no antenna, but is still being picked up by his receiving antenna mounted behind his house.

Since [Mark] doesn’t really cover the hardware he used, you will need to look back at [Steve's] original design schematics for more information.

[Read more...]

Hackaday Links: November 10, 2011

Experimentations with haptics

[Chris] sent in two videos (1, 2) documenting his experiments with haptic feedback. He’s recording the position of a DC motor and can either play it back or send it to another motor. It’s very similar to the kissing robot we saw earlier this year, but we’re not making any judgments.

Mobile Emergency Repeater go bag

[Nick], a.k.a. [KF5JAK] sent in a few pics of his emergency/disaster relief amateur radio go bag. With a 3G connection via a cell phone, the MER can be used with EchoLink.

Launchpad MIDI booster pack

Earlier this month we lamented the dearth of add-ons for the TI Launchpad. The folks on the 43oh forums just came out with a MIDI booster pack. Time to dust off that old Radio Shack keyboard, we guess.

Macro photography with OH GOD WHARGARBL

You know camera lenses work both ways, right? [Karl] has been experimenting with this very idea by mounting a camera lens backwards and running a few wires so it’s electrically connected as well. Check out an example shot.

Keeping tabs on your kids’ homework

[Janis] doesn’t live with his kids but he wanted to keep track of their homework. He set up a document scanner that sends those worksheets straight to his email inbox. All he has to do is annotate them and send them back. This guy’s doing it right.


Get every new post delivered to your Inbox.

Join 94,586 other followers