Mobile Transmitter Gets Internal GPS And Bluetooth

While [Selim Olcer] was relatively happy with his Kenwood TM-D710a radio, he didn’t like the fact that it needed a bulky external GPS “backpack” for APRS location data. So he decided to crack open the head unit and see if he couldn’t integrate his own GPS hardware (machine translation). Not only did he succeed, but he even threw in Bluetooth compatibility for good measure.

With the repair manual circuit diagrams in hand, it was no problem to find the GPS RX and TX lines that were being broken out to the external connector. Unfortunately, the radio’s electronics are all 5 volts and the GPS module [Selim] wanted to use was only 3.3 V. So he came up with a small PCB that included not only the voltage regulator to power the GPS module, but also some voltage-dividers to level shift those signals.

Since the Kenwood TM-D710a was already designed to accept a GPS upgrade module, he just needed to change some configuration options in the radio’s menus for it to see the new hardware. Technically the project was done at this point, but since there was still room in the case and he had a GPS module spitting out NMEA sentences, [Selim] tacked on a common Bluetooth serial module so he could see the position information on his smartphone. With an application like APRSdroid, he now has a nice moving map display using the position pulled from the radio’s GPS.

With this modification done it looks like the head unit is ready to go, but that’s only the beginning for a mobile rig. Now we want to see how he integrates the whole thing into the car.

Hams Gone Wild: Amateur Radio Field Day 2019

Of all the images that amateur radio conjures up, the great outdoors doesn’t usually figure heavily. People seem to think hams sit in a dark room at a desk heavy with radio gear, banging out Morse code into late into the night and heedless of the world outside the window. All of which sort of sounds like hard-core gaming, really.

And while that image certainly applies in a lot of cases, hams do like to get out and about at least once a year. That day is upon us with the 2019 Amateur Radio Field Day. Hams across North America reserve the fourth full weekend of each June to tear themselves out of their shacks and get into the world to set up operations in some kind of public venue, generally a park or other green space. Part cookout, part community outreach, and part slumber party – it lasts all weekend and goes around the clock – hams use field day as a chance to show the general public where amateur radio really shines: real-time worldwide communications under austere conditions.

It’s also a chance to get folks excited about getting their license, with many Field Day locations hosting “Get on the Air” stations so that unlicensed folks can try making a contact under the supervision of a licensed operator. Licensed but underequipped hams also get the chance to spin the knobs on someone else’s gear, and maybe line up that first rig purchase. And there are plenty of opportunities to learn about new modes as well, such as FT8 and WSPR. As an example your scribe is looking for some guidance on getting started with APRS, the automated packet reporting system that’s used for things like high-altitude balloon tracking.

If you have any interest at all in learning how to properly operate radio equipment, you owe it to yourself to track down the nearest Field Day location and stop by. The American Radio Relay League (ARRL) has a ton of Field Day information, from a map to locate the 1500 Field Day sites to rules for the contests that will be run that weekend to guides for setting up and operating an effective Field Day setup. There will be 40,000 hams out there this year, and they’d all be thrilled if you drop by and ask a few questions.

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Raspberry Pi Is Up Up And Away

BACAR — Balloon Carrying Amateur Radio — is just what it sounds like. A high-altitude balloon carries experiments and communicates via amateur radio. [ZR6AIC] decided to fly a payload in a local BACAR experiment. The module would send its GPS position via the APRS network and also send a Morse code beacon every seven minutes. It also sends other data such as temperature, and has an optional camera fitted.

The hardware used was the ubiquitous Raspberry Pi along with an associated daughterboard for transmitting on the 2 meter ham band. An RTL dongle took care of the receive portion and another dongle provided GPS. A DS18B20 temperature sensor provides the temperature data.

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APRS Repeaters Get The Signal Out Of Mammoth Cave

APRS Cave-Link uses the amateur radio’s Automatic Packet Reporting System (APRS) inside caves to get their position data (and other messages) out.

Imagine that you’re coordinating a large scale search-and-rescue mission in a cave. You need to know where all your groups are, and whether or not they’ve found anything. But how do they all communicate to the command center?

You’d guess radio, but you’d guess wrong. Radio doesn’t propagate well at all in a maze of twisty passages, all alike; rocks absorb radio waves, especially in the VHF/UHF range that’s best suited for most small radios. In the past, you’d run wire and transmit along it. This article runs through the options in detail. But adding miles of wire to your already heavy caving and climbing gear is a nuisance or worse.

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Tiny Radio Tracks Your Balloons

The name of the game in rocketry or ballooning is weight. The amount of mass that can be removed from one of these high-altitude devices directly impacts how high and how far it can go. Even NASA, which estimates about $10,000 per pound for low-earth orbit, has huge incentives to make lightweight components. And, while the Santa Barbara Hackerspace won’t be getting quite that much altitude, their APRS-enabled balloon/rocket tracker certainly helps cut down on weight.

Tracksoar is a 2″ x .75″ x .5″ board which weighs in at 45 grams with a pair of AA batteries and boasts an ATmega 328P microcontroller with plenty of processing power for its array of on-board sensors. Not to mention everything else you would need like digital I/O, a GPS module, and, of course, the APRS radio which allows it to send data over amateur radio frequencies. The key to all of this is that the APRS module is integrated with the board itself, which saves weight over the conventional method of having a separate APRS module in addition to the microcontroller and sensors.

As far as we can see, this is one of the smallest APRS modules we’ve ever seen. It could certainly be useful for anyone trying to save weight in any high-altitude project. There are a few other APRS projects out there as well but remember: an amateur radio license will almost certainly be required to use any of these.

APRS Tracking System Flies Your Balloons

Looking for a way to track your high-altitude balloons but don’t want to mess with sending data over a cellular network? [Zack Clobes] and the others at Project Traveler may have just the thing for you: a position-reporting board that uses the Automatic Packet Reporting System (APRS) network to report location data and easily fits on an Arduino in the form of a shield.

The project is based on an Atmel 328P and all it needs to report position data is a small antenna and a battery. For those unfamiliar with APRS, it uses amateur radio frequencies to send data packets instead of something like the GSM network. APRS is very robust, and devices that use it can send GPS information as well as text messages, emails, weather reports, radio telemetry data, and radio direction finding information in case GPS is not available.

If this location reporting ability isn’t enough for you, the project can function as a shield as well, which means that more data lines are available for other things like monitoring sensors and driving servos. All in a small, lightweight package that doesn’t rely on a cell network. All of the schematics and other information are available on the project site if you want to give this a shot, but if you DO need the cell network, this may be more your style. Be sure to check out the video after the break, too!

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MicroModem, For Data Transmission Explorations

modemThem kids with those Arduinos don’t know what they’re missing. A serial connection is just too easy, and there’s so much fun to be had with low bandwidth modems. [Mark] made the MicroModem with this in mind. It’s a 1200 baud AFSK modem, capable of APRS, TCP/IP over SLIP, mesh network experimentations, and even long-range radio communication.

As the MicroModem is designed to be an introduction to digital wireless communication, it’s an extremely simple build using only 17 components on a board compatible with the Microduino. The software is built around something called MinimalProtocol1, a protocol that will be received by all other listening stations, features error correction, and automatic data compression. There’s also the ability to send TCP/IP over the link, which allowed [Mark] to load up our retro site at a blistering 1200 bps.

The code is extremely well documented, as seen on the Github for this project, with board files and even breadboard layouts included. [Mark] has three PCBs of his prototype left over, and he’s willing to give those out to other Hackaday readers who would like to give his modem a shot.