Tag Archives: APRS

High-Altitude Balloon Project Update #3 – Launch!

Our High-Altitude Balloon made it to the edge of space! The image above was taken from our HAB at an altitude of over 90,000 ft!

After many months of work, raising funds to finance the project, teaching STEM sessions in local High Schools, and an open-house to test the Balloon Platform and to learn about Amateur Radio; our High-Altitude Balloon Project (HAB) Team finally got the chance to launch and track our Balloon. We launched our Balloon from the Elementary School in Winchester, NH.

High-Altitude Balloon - Setting Up Our Gear On Site
Setting Up Our Gear On Site

Students, Teachers and Club Members came out to be part of the launch and to track our HAB. The first step was to move all of our gear to the center of the athletic fields at the school and organize all of our equipment.

High-Altitude Balloon Flight Platform Final Assembly and Test
Flight Platform Final Assembly and Test

Next, we attached the GoPro video cameras, satellite tracker and the battery pack for the Flight Computer and 2M APRS transmitter to the flight platform. We used an APRS capable HT to confirm that the flight computer and APRS transmitter were working.

Rigging the High-Altitude Balloon Flight Line
Rigging the Flight Line

We rigged the 40 ft. flight line which connected the HAB’s flight platform, recovery parachute, and the balloon.

High-Altitude Balloon Inflation
Balloon Inflation

And then came the inflation of the balloon from the Helium tank. The winds were gusting to about 12 mph at this point which made inflating the balloon a little tricky. When filled, the balloon was about 6 ft. in diameter on the ground.

High-Altitude Balloon Launch!

With both GoPro cameras running on the flight platform, we were ready to launch. A 10-second countdown and the balloon was up and away!

Tracking Our High-Altitude Balloon
Tracking the HAB

We watched the balloon from the ground as it soared off into the clouds. The 2M APRS tracking system worked perfectly and we spent the next several hours at the launch site, at lunch, and in our cars tracking the HAB on aprs.fi.

Tracking Our High-Altitude Balloon Flight Path On APRS.fi
HAB’s Flight Path On APRS.fi

Our HAB’s flight path took it across Massachusetts where it reached a maximum altitude of 91,700 ft. above sea level (ASL).

Looking Upward at the High-Altitude Balloon (Near Burst)
Looking Upward at the Balloon (Near Burst)

The balloon reached a diameter of approximately 30 ft before it burst. After the balloon burst, the parachute deployed and the payload descended to a landing in the northeast corner of Rhode Island.

High-Altitude Ballon at Recovery Site in Rhode Island
HAB at Recovery Site in Rhode Island

A combination of the APRS transmitter data and the onboard sounder allowed the landing location to be pinpointed and the flight platform recovered with help from a local resident.

The onboard GoPro video cameras captured some awesome video during our HAB’s ascent! All of the media captured by everyone who participated in the launch as well as the APRS data allowed us to produce the video above. Turn up your speakers and give it a play in full-screen mode to enjoy the experience what we shared!

By the time we had launched, the school year was at an end so we will have to wait until the fall to work with the students and teachers who were part of our STEM project to analyze the data from the flight. All in all, our HAB project has been an amazing experience for all involved. We are planning another HAB STEM experience and launch with additional schools in the fall.

We want to especially thank all of our donors whose generous contributions made this project possible.

Fred, AB1OC

Hashtag: #N1FDHAB

Go Kit for Field Day and EMCOM

We’ve been thinking about building a portable Go Kit for VHF/UHF Emergency Communications (EMCOM) and Field Day Applications for a while now. The following is a list of our requirements for a Go Kit –

  • 2m and 70cm operation with FM simplex and repeaters
  • APRS capability and tactical display for portable coordination
  • Digital messaging capability
  • Weather band monitoring capability
  • AC Power with flexible battery backup options

A plan to build our Go Kit came together during our trip to the Dayton Hamvention this year.

EMCOM Go Kit - Kenwood TM-D710GA At Dayton
Kenwood TM-D710GA At Dayton

The heart of any Go Kit is the Transceiver. We’ve been using Kenwood equipment for our APRS iGate for some time now and we have had good results with it. Kenwood’s latest 50W transceiver with APRS is the TM-D710GA. This unit provides full support for APRS tactical applications and now includes a built-in GPS receiver making it ideal for our Go Kit application.

EMCOM Go Kit - AvMap GeoSat 6 APRS Tactical Display
AvMap GeoSat 6 APRS Tactical Display

We have been using the Kenwood TM-D710 along with an AvMap GeoSat APRS display in our APRS iGate setup and the combination works very well. The AvMap display lets one see the location of portable and mobile APRS stations on a map display. This arrangement is perfect for coordinating activities in an EMCOM situation. The AvMap GeoSat 6 APRS display is no longer in production but I was able to locate a nearly new unit on eBay.

EMCOM Go Kit Packaging


EMCOM Go Kit - iPortable Enclosure
iPortable Enclosure

We had a chance to look at the iPortable enclosure at Dayton and decided that their Pro 2 4U deep unit would be a good choice for our Go Kit application. The iPortable enclosures are based on a portable rack mount case and include a DC power system, speaker and headphone hookups, a light, and provisions for a cooling fan.

EMCOM Go Kit Construction


EMCOM Go Kit - Radio Shelf
Radio Shelf

With all the components in hand, we began the construction of our Go Kit. Reliability is important in any portable system like this so we put some time into securely mounting all of the equipment and neatly arranging the cabling. First came the shelf which holds the Kenwood transceiver and a SignaLink USB sound card. A combination of drilling the shelf to secure gear with large cable ties and #8 stainless hardware was used here.

EMCOM Go Kit - Coax Connector Cables
Coax Connector Cables

Our iPortable case was equipped with both SO-239 and N-connectors on the front panel to allow for antennas and feed lines equipped for either connector type. To make the change over between the connector types easy, we installed separate PL-259 jumper cables for each connector. One simply connects the appropriate jumper to the radio.

EMCOM Go Kit - Display and Power Shelf
Display and Power Shelf

The power and AvMap display shelf were next. The AvMap display mount was dissembled and modified to accept a custom mounting bracket.

EMCOM Go Kit - PWRgate Battery Interface and Charger
PWRgate Battery Interface and Charger

The iPortable enclosure was drilled to mount a West Mountain Radio PWRgate to handle backup battery charging and management. The PWRgate supports instantaneous switching between an AC power supply and a backup battery and can accommodate a wide range of battery types and sizes.

EMCOM Go Kit Backup Battery
Backup Battery

The PWRgate was configured to properly charge our 18AH AGM backup battery. Note the use of a fuse in series with the battery for safety reasons. We used a Powerwerx SPS-30DM adjustable power supply set to 14.5Vdc to operate our Go Kit and to provide the proper charging voltage for our AGM battery.

EMCOM Go Kit Operation


EMCOM Go Kt - Diamond X-30 Antenna and Mast
Diamond X-30 Antenna and Mast

The last piece of the setup was the antenna. We wanted something that was portable, easy to set up and would provide good performance. We choose a Diamond X-30A 2m/70cm ground plane antenna and mounted it on a 12′ fiberglass push up mast. The feed line is made from 25′ of LMR-400UF coax. Several bungee cords are used to attach the mast to a fence post or other vertical structure.

EMCOM - Finished Go Kit In Use
Finished Go Kit In Use

The picture above shows the completed Go Kit in operation. We typically set one side of the Kenwood TM-D710GA to operate as an APRS transceiver and Digipeater and the other side to operate on a local repeater or simplex FM. The SignaLink sound card is used with a laptop computer running Fldigi and NBEMS for messaging applications. The iPortable case has a 13.8V lighter socket which connects to a power brick to power our laptop PC.

EMCOM Go Kit Packaged for Transport
Go Kit Packaged for Transport

The Go Kit is quite portable when closed. All of the equipment and cable connections are enclosed and protected by the case’s removable end caps. We’ve tested our Go Kit during our club’s weekly repeater net and it worked great. The first real use of our new Go Kit will be at Field Day this year. It will be located in our public information tent and will be used as a “talk-in” system.

Fred, AB1OC

Crossing A HAB Off The Bucket List….

Back in 2010, I was a postdoc in the particle theory group at National Taiwan University in Taipei. I was working with a buddy, a German fellow, and in the middle of talking about made up particles (actually they’re real) in imaginary time (this is an actual “thing”), he showed me a neat YouTube video that he found. As we watched, we saw two young fathers design and launch a high altitude balloon (HAB) to stimulate interest in their very young sons. Of course, the best part of this entire endeavor was the video footage they recorded during the ascent/descent. It was awesome; in the original definition of the word. I immediately developed HAB envy and wanted to do this myself. I told my future XYL, Anne, about this and she said if I came back to the U.S., she would help me design one.

Fast-forward to 2011. I came back home, and though Anne offered to help, I was adjusting to a new job in VA and had zero time to dedicate to it and coupled to that, zero money. The dream would have to wait.

Fast-forward to early winter 2016 (I think it was early 2016). Fred, Anita, Jamey, Tony, myself, and others were sitting at the Dartmouth-Hitchcock facility during one of our Youth Days. We had just finished lunch and were brainstorming ideas to engage young people in amateur radio. Fred had mentioned, how about a high-altitude balloon carrying APRS? Bing. Bang. Boom.  That was all I needed to hear. This was the opportunity literally right in front of me to check the box. So, as you can guess, I was in.

The team had a lot of work in front of us. Some of you have heard us proselytizing the good word at our meetings. This whole project would not work if it were just about a solitary, singular balloon launch. There had to be a hook; had to be something that would allow us to continually interact with the potential participating students. What we had decided was to create a STEM opportunity in the classroom. For those of you unfamiliar with STEM, it stands for Science, Technology, Engineering, and Mathematics. It represents a body of activities and teaching to foster and nurture this type of education in students. It takes the form of FIRST robotics, programming courses for kids, DIY electronics for kids. You name it, it’s probably a “thing” already. So this is what we tasked ourselves with.

To move forward, we had to establish a potential curriculum and target schools that we could work with and hopefully engender a long-lasting partnership with. The ideal case scenario we envisioned would be, to begin with, students as freshman and work with them until graduation; maybe even getting a senior thesis out of it.

I won’t bore you with all the details, but to name a few, we had bi-monthly WebEx conversations to discuss how to move forward, solicited schools, developed a presentation schedule, created a TON of PowerPoint slides to be presented in the classroom, ordered and tested the HAB and its components, organized an Open House at Fred/Anita’s QTH, and of course figured out a launch date — let’s talk about that next.

Ah, launch time. The culmination of 7+ years of waiting was actually going to happen. I could measure time by prepending the phrase “T-minus” to my system of units — Pretty cool. The morning of, many of us gathered at the requisite spot; the anticipation was pretty palatable. After the exact launch locale was ascertained, we prepped and began to inflate the balloon. Spoiler alert: We under-filled the balloon due to a misunderstanding of the instructions from the company which led to a longer flight time. The moment I let the balloon go, I swear my mind went through all the charts I made, all the prep work the team went through, and an overwhelming sense of pride at the accomplishment we achieved.

We quickly cleaned up and adjourned to a local restaurant where we viciously ate our food and just as viciously scoured the interwebz (aprs.fi) to get the latest update of the balloon’s telemetry. Since the update time was about one minute, it was obvious that Einstein’s theory of Special Relativity was at work; each minute felt like an eternity in my reference frame.

Finally, touchdown! In RI. Ok…sure. We predicted SE of Worcester, but it was RI. Fred called me a few times to update me on the HAB’s status after recovery. I asked him to let me know when the data would be available in the Dropbox. When I saw this, I instantly turned to MATLAB and created the following plots from the telemetry data on the flight computer. (Note: It’s update time is every 6 sec, so we get more accurate updates than APRS)

IMHO, I think the most interesting plots are those of the pressure vs altitude of the HAB and the temperature vs altitude. These are fascinating since:

  1. We have theoretical models from NASA with which to compare with.
  2. It’s unfathomable we can record this data THAT HIGH UP with such simple tools.

Below, I’ll only show the results from the ascent. (The descent essentially looks the same). Also, for posterity, I included the NASA predictions which for those of you who are more mathematically minded (all of you, right?!) can sink your teeth into.

High Altitude Balloon

High Altitude Balloon

High Altitude Balloon

What I find fascinating is that the pressure the HAB recorded (shown in blue) lies essentially on top of the NASA predictions (shown in black). Moreover, the temperature shows good agreement qualitatively: namely a sharp decrease until a particular altitude, then it levels off, and finally begins to increase again. Where those boundaries occur differs between NASA and our local measurements from Winchester, NH. But, the trends are the same. Very encouraging. The next most interesting plots are those derived from the telemetry data. The first is the ascent altitude vs time:
High Altitude BalloonThe vertical speed seems to be essentially constant. This makes sense so long as the vertical lift force from the Helium balances out the downward force of gravity. And this is essentially what we are seeing here and is what is modeled by our HAB prediction website. On the way down, the curve looks a bit more interesting:

High Altitude Balloon

Initially, the HAB seems to be accelerating (since there is some curvature to the line until about 240 min of elapsed time), but after it encounters more air as it falls, it seems the parachute is deployed and therefore reaches terminal velocity (e.g. constant speed)


The upshot of all this stuff is I made a TON of plots on launch night (from the APRS data) and the following morning (from the flight computer data) which I have shown here. I won’t bore you with the other results, but there is a wealth of info one can calculate and learn about.

This entire experience has been an absolute pleasure to be a part of on many, many levels. I just hope we, the HAB team of NARC, have begun to inspire some kids in STEM and amateur radio due to our efforts.

Best and 73,

Brian, AB1ZO

Hashtag: #N1FDHAB

How To Track Our High Altitude Balloon

I wanted to share some information about our tracking our High Altitude Balloon as it flies. Our balloon will carry’s a GPS receiver and a 2m APRS Transmitter.

High Altitude Balloon Flight Platform
HAB Flight Platform

The on board APRS transmitter will operate on the Amateur Radio standard terrestrial APRS frequency of 144.390 MHz and will transmit our HAB’s position, heading, speed, altitude and other telemetry data every minute during the HAB’s flight. The transmitter is battery-powered and generates a 250 mW signal into a dipole antenna suspended from the HAB’s flight platform. The HAB will use N1FD-11 as its call sign.

High Altitude Balloon On aprs.fi
HAB On aprs.fi

The HAB’s APRS packets will be picked up by ground-based Digipeaters and iGates and will be relayed to aprs.fi where the HAB’s current location and flight path can be tracked.  You can click on the link in the previous line to see the HAB’s current location and flight track.

High Altitude Balloon Flight Path Prediction
HAB Flight Path Prediction

Based upon online HAB flight prediction calculators that we have been using, we expect the HAB’s flight to last a little less than 2 1/2 hours. The HAB should reach an altitude of over 102,000 ft before the balloon bursts and the parachute on the flight platform brings it back to the ground at a safe speed. The above prediction will likely change as we get closer to an actual launch but most predictions have our HAB traveling approximately 100 km between its takeoff point and landing.

High Altitude Balloon APRS Packet Information
HAB APRS Packet Information

Aprs.fi will also store and display a copy of all of the APRS AX.25 packets transmitted by the HAB during its flight. Of particular interest to the STEM element of the flight will be the Balloon’s data on atmospheric temperature and pressure conditions at different altitudes.

All you need to track our HAB during its flight is Internet access and a web browser. Just click on one of the aprs.fi links here to see the HAB’s current location and altitude. If you have an APRS ground station, you may also be able to receive our HAB’s telemetry directly during the flight.

We need cloud cover which is less than 50% and ground wind speeds below 15 mph to launch our HAB. Will will post a final launch date and plans in the Youth Forum on our website. Our next possible launch window is on Saturday, June 3rd. We are all pulling for good weather so that we can launch!

Fred, AB1OC