After my visit to Fairbanks, Alaska back in July 2022, I chatted with a friend who lives in Fairbanks. He agreed to host a radiosonde receiver at his house just north of town. Since I wasn't traveling to Fairbanks again in 2022, I shipped him all the parts necessary for the installation.

This station is the standard Raspberry Pi and RTL-SDR Blog v3 that I have been shipping around to Houston and other sites. radiosonde_auto_rx runs inside a docker container, which makes it trivial to install and update the software. For remote monitoring and control, wireguard is the way to go.

Antenna

My go-to antenna for radiosonde receiving is a quarter-wave ground plane antenna. They are super easy to build, very inexpensive, and work better than commercially-made antennas.

But a home-made quarter-wave vertical antenna has one major flaw: ice. Ice buildup on the elements will not only cause it to detune, but there is also a potential for mechanical failure. Hardware store 14-gauge copper wire just isn't strong enough to hold up ice.

Since Fairbanks gets a lot of snow ...

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A recent work trip brought me to Hokkaido, Japan. Taking a look at Sondehub beforehand, I noticed a few radiosonde launch sites on the island. My work would bring me closest to the Kushiro radiosonde launch site, so maybe if I had some free time I could go watch a launch.

Research

Before leaving for the trip, I contacted Shaun JH1HNB/KJ6VGQ, who was uploading radiosonde data to Sondehub. Shaun lives in Tokyo, and has written some blog posts about his experiences.

Shaun gave a presentation (pdf) in February 2022 to the Tokyo International Amateur Radio Association. The presentation was about using radiosonde_auto_rx or a rdzTTGOsonde to receive radiosondes.

I also did some research on the Japan Meteorological Association's radiosonde webpage (pdf), which has a lot of information about the program. Their online map showed that this site uses an autolauncher, but doesn't indicate which type of radiosonde is launched.

Since radiosonde_auto_rx can receive all three of the types of radiosondes that are launched in Japan, I felt confident that I could receive any radiosonde that was taking measurements.

Kushiro ...

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On the last day of my recent trip to Fairbanks, Alaska, I finished up work a bit early and headed to the airport to see a radiosonde launch. Looking at satellite imagery before my trip, the launch location has a few buildings so I thought it might be a manually-launched site like Inuvik or Newfoundland.

However, when I arrived, through the fence I saw a Vaisala AS41 autolauncher, just like my local radiosonde launch site across the bay in Oakland, California. No one to talk with this trip.

I arrived just before 3pm local time (2300 UTC), and the autolauncher was beeping away, indicating that the balloon was filling with hydrogen. I set up my mobile radiosonde_auto_rx station, with a mag-mount antenna and RTL-SDR dongle. Running the software inside a docker container makes it easy to install and update.

The radiosonde was turned on and transmitting on 405.3 MHz inside the autolauncher, but the expected launch at 2300 UTC came and went with nothing happening. Interesting, maybe something was wrong? My local Oakland station launches at exactly 1100 and ...

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Back in October 2021, the excellent team behind Sondehub added several features to the map. They added launch site locations, grabbed from the official NOAA database. Clicking on a particular launch site allowed a user to generate a weeks worth of flight predictions based on the most recent GFS run. Cool!

The red lines on this prediction map of Oakland show the next 14 launches (7 days). As with any prediction of the future, the further out you go the worse the prediction.

Reverse predictions (pdf) were also added, for predicting where a radiosonde was launched from. This feature would have been very helpful when I was trying to find the Monterey Bay launch location.

Scrolling around the new map, I saw a launch site just east of Houston, Texas. I knew some people that lived in Houston, so I sent them a radiosonde receiving station. The hardware was almost identical to the Santa Cruz station, except that this station is entirely inside a home. No weatherproof case was needed, which is great because I didn't really want to figure ...

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Now that the pandemic has tapered off a bit, I took another short trip up to Inuvik, NWT. While I was up there, I visited the Environment Canada Weather Station, and participated in a radiosonde launch.

The big news out of Inuvik during this trip was that the road from the airport to the town has been paved! The road is much smoother, and I don't need to worry about windshield cracks every time a big truck passes.

Since my 2016 visit, the site has been upgraded with modern equipment. The old Electrolyser Corporation hydrogen generator was replaced with a Proton Hogen unit, all housed in a modern building with explosion-proof light switches, electrical outlets, etc.

I arrived just before the Midnight UTC launch, and Chris already had the balloon inflated and was working on the radiosonde transmitter. As I saw in Newfoundland, Canada has transitioned to the Graw DFM-09 radiosonde.

To my surprise, he actually let me release this radiosonde. This was my first radiosonde release, and it's very similar to a bursting HAB release. One interesting aspect of ...

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Just after setting up a remote receiving station in the hills above Santa Cruz for tracking radiosondes launched from Monterey Bay, I started noticing some weird stuff with the station. The station would detect a LMS6-403 radiosonde, but was unable to actually decode anything. The "jamming" signal was always on the same frequency of 400.259 MHz, and occurred daily around noon and midnight UTC.

I speculated that it might be radiosondes from Vandenberg Space Force Base, approximately 300 km (~180 miles) south of the receiver along the coast of California. Although it would be cool to receive those radiosondes, the purpose of this station was to track the Monterey Bay radiosondes, so I put that frequency on the blacklist and turned my attention to the task at hand.

New LMS6-403 Radiosonde Version

A few days later, my curiosity got the better of me, and I started to investigate these signals. Over the course of four days, I did decode a single packet each from two radiosondes. Based on the location, these definitely were from Vandenberg, but the signal must ...

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I recently went on a work trip to Newfoundland, Canada. Checking Sondehub before I left, I saw that there were two radiosonde launching stations on the Island of Newfoundland, one on the west side in Stephenville, and the other on the far east end in St. John's. And as luck would have it, I was traveling to Lewisporte, which is on the Trans-Canada highway almost halfway between the two launching sites. I might be able to receive both sondes at the same time!

As far as I could tell, the radiosondes launched at both of these sites were Graw DFM-09P (pdf), which transmit around 403 MHz. One interesting thing about these radiosondes is that they don't transmit a serial number with every packet, so it takes a while to determine the serial number of the radiosonde you are receiving.

Receive Station

Since I was traveling, I needed a portable station with two receivers. This is very similar to my standard radiosonde receive station at home, and I didn't use a preamp or filter.

The Comet M-24M dual-band amateur radio antenna ...

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Taking a look at SondeHub one evening in early July 2021, I noticed some radiosondes down in the Monterey Bay, about 75 miles south of San Francisco. There seemed to be one per day in the afternoon on most days. The Naval Postgraduate School launches radiosondes very infrequently for their meteorology program, but these seemed to be launched from Watsonville or Salinas, not the main NPS campus in downtown Monterey.

Then, on Monday July 12th, there was a flurry of radiosondes launched. I received a total of 5 of them from my station in Los Gatos. This station does not have good coverage in the direction of Monterey, and only starts receiving radiosondes when they rise up to 5,000 meters (~16k feet), above nearby mountains.

This rate of around 5 launches per day was sustained until Friday July 23rd. I was pretty busy with other things in life during this period, so I didn't really pay attention to these launches or landings.

Then on August 20th, many radiosondes started appearing in the sky again, and this time I was ...

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It's been about 6 months since I started receiving AIS signals using a RTL-SDR Blog v3 dongle. My station is decoding between 35 and 70 ships at any given time, depending on time of day and how many ships there are in San Francisco Bay.

The RTL-SDR Blog v3 dongle is a really inexpensive software-defined receiver. The "official" version costs about $25, and knockoff versions can be had for $10 or less. However, there's a reason why knockoff versions are less than half price, they use very cheap components and drift like crazy. I have several friends who bought the cheap version only to find that they just don't work, then purchased another knockoff that also didn't work. So save yourself the hassle and just buy a real one.

The very old laptop I was running rtl-ais and kplex on was starting to die, with several unknown kernel panics over a few days. I purchased a new shack computer, but wanting to keep the base OS clean, I decided to play around with containerizing rtl-ais and kplex.

Containerization is a ...

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The prevailing winds here in California blow from west to east, from the Pacific Ocean towards the Sierra Nevada mountains. Radiosondes launched from Oakland International Airport float in these winds, landing east of Oakland in the Central Valley, or south in the hills east of San Jose. I never recover the ones that land in the Central Valley, as driving 2 hours each direction during rush hour to recover a balloon is a bit too far for me. Only rarely do they land in populated areas in the Bay Area, and almost never on the Peninsula or in the city of San Francisco.

This map (code below) shows the landing locations of all the radiosondes launched from Oakland since November 2020, when I started receiving them. Each red dot is the last position received by my two receiving stations, and is typically less than 1,000 meters altitude. This map shows 337 radiosondes, and I have removed the radiosondes launched up north by UCSD during atmospheric river events. As you can see, they are mostly south and east of the ...

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