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  1. Fairbanks Radiosonde Receiving Station

    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.

    Block diagram of receiving station

    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.


    My go-to antenna for radiosonde receiving is a quarter-wave ground plane antenna. They are super easy ...

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  2. Kushiro, Japan, Radiosonde Autolauncher

    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.


    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.

    Presentation by Shaun JH1HNB

    I also did some research on the Japan Meteorological ...

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  3. Fairbanks Radiosonde Autolauncher

    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.

    Fairbanks Vaisala autolauncher

    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 ...

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  4. Houston TRACER Radiosondes

    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!

    Oakland airport launch predictions

    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 ...

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  5. Inuvik Radiosonde Launch

    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.

    Dempster Highway sign

    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.

    Hogen Hydrogen Generator

    I arrived just before ...

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  6. LNA teardown

    Receiving radiosondes is very easy, provided that you have line-of-sight to the balloon. Any mountains, buildings, trees, or any other obstruction will block the radiosonde signal. If you're close to a launch site, you don't need an expensive antenna or LNA, so save your money and buy dinner for a fellow sonde chaser after your next successful recovery.

    Low-Noise Amplifier

    If you live within 200 km of a radiosonde launch site, or have line-of-sight to the balloons up in the air, you don't need a preamp/LNA. Standard RTL-SDR dongles are sensitive enough to receive the 60 mW radiosonde transmitter out at several hundred km away, even with 50 feet of RG-8/LMR-400 coax and a splitter.

    But maybe you're ...

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  7. Vandenberg Radiosonde Launches

    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 ...

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  8. Newfoundland Radiosonde Launches

    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 ...

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  9. Receiving Monterey Bay Radiosondes

    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.

    Early July 2021 Monterey radiosondes

    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 ...

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