As I’ve mentioned in a previous column, I have had an amateur radio licence (both basic and advanced certifications) for decades but only relatively recently returned to the hobby, known more commonly as ham radio.
Over the past year or so, my interest has been really piqued by a small team of ham radio enthusiasts in, of all places, Memphis, Tenn. A weekly radio show produced there by Tom Medlin, who operates as W5KUB, led to a chance meeting with another operator, Bill Brown, WB8ELK.
For years, Brown had been launching balloons as a hobby and tracking them via small radio transmitters. The men’s encounter led to an effort to launch a radio-equipped balloon that might possibly circumnavigate the planet, broadcasting its location every 10 minutes or so.
When I first learned about their efforts, they were on attempt number five. How exactly the early attempts ended I’m not sure, but I was captivated that amateurs could put together a project that could conceivably see a small balloon circle the globe while broadcasting details that others could capture thousands of kilometres away.
So with each attempt I began my efforts to pick up the signal from their balloons. However, with the prevailing winds at altitude moving mostly west to east, I had to wait until the balloon had nearly completed a full circuit of the earth before my simple antenna system would have a chance of detecting the balloon’s signal.
With each attempt their balloon would travel farther – Spain, Poland, China, for instance – before a storm brought it down. I eagerly followed the path of the balloon, on various mapping sites. These would take the weak signals it transmitted and that were intercepted by ham radio operators within range and plot the corresponding positional data.
Then came attempt number nine. As before, I began tracking the balloon, seeing its signal picked up by amateurs elsewhere on the planet. With each successive day I became more optimistic that I too might have a chance. Following a sine wave pattern of the jet stream, all the way up at 42,000 feet of altitude, the balloon moved across the Atlantic, Europe, the Middle East, northern India, China, Japan, and finally the Pacific.
And so it was that when the W5KUB balloon was about to complete that first loop of the planet, I picked up its beacon, while it was high over Las Vegas. Needless to say, I was elated. In two brief bursts of digital data the balloon was able to transmit its position, altitude, heading, and speed.
A day later the balloon crossed its launch meridian to complete that elusive circumnavigation. Now, as I write this, the balloon is on its third lap, continuing to maintain an altitude between 40,000 and 43,000 feet. That altitude varies slightly with atmospheric pressure. Laps appear to be taking about 20 days.
This third lap has illustrated nicely how unpredictable wind speeds and directions can be. With just a few hours to go before crossing its home meridian, the balloon made a sharp 90-degree turn and headed north, over Saskatchewan, well into the high Arctic, eventually coming back to lower latitudes and even B.C. airspace.
Picking up the balloon’s radio signal is no mean feat. First of all, the power output of the transmitter is a mere 10 milliwatts. To put that in perspective, five million such transmitters would be the equivalent of one Vancouver AM radio station
This signal uses a highly specialized protocol called WSPR, weak signal propagation reporter, designed by Nobel Physics laureate Joe Taylor, also known as ham radio operator K1JT.
WSPR and other weak signal modes have brought an entirely new dimension to ham radio, making it possible to communicate over vast distances, even in conditions that are regarded as poor for radio.
In my case, I use a very simple piece of wire, about 30 m in length, slung between two trees about 4 m above the ground. This wire is connected to a software-defined radio, an inexpensive device that evolved from converters developed to allow old TVs to receive digital signals. The rest involves the magic of free software that takes in the weak signal pulses from the balloon and other transmitters all over the planet, decodes them, and displays the useful information they contain.
As for the balloon design itself, Tom Medlin notes that they have tried various versions, finding that the dollar store mylar varieties tend to climb only to 30,000 feet, within reach of journey-ending high cloud tops.
More reliable, and also more costly, at around $200 for the balloon alone, is a model known as the SBS-13. Mr. Medlin describes it as looking like a large clear plastic clothing bag, which reaches a size of about two metres in length when the balloon is at 45,000 feet. Interestingly, the launch team uses hydrogen rather than helium for the balloon’s lift. There are several reasons for this, among them being cost (helium has become notably expensive in recent years), extra lift for a given weight, and longevity of the balloon, hydrogen not diffusing as readily through the balloon skin as does helium.
Perhaps most amazing about the entire project is the two-gram electronics payload designed by Eduard Voiculescu, YO3ICT, in Romania. This WSPR transmitter, along with a GPS receiver, is powered by a lightweight solar panel and assembled by Medlin under a microscope.
Want to follow the balloon for yourself? Go to WSPRnet.org, click on Map, select 20 m for the radio band, and enter W5KUB in the Call box. Daylight hours only! Or try APRS.fi, enter W5KUB-18 in the Track callsign box. This latter site interpolates data from the WSPR transmission and can look back up to seven days.
Lest you think that balloon experiments are something from yesteryear, it is worth noting that Project Loon balloons (from Google parent Alphabet) are now delivering internet service across Kenya. Three of the Loon balloons were over Vancouver last month.
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