ChannelSPURIOUS EMISSIONS
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Episode 14 · Radiosondes · Series 01: The Listening Station

What does a weather balloon feel on the way up?

A frame from the draft of episode 14, RadiosondesComing soon
Release
Coming soon
Length
6:30
On the dial
400 to 406 MHz
Signal
Radiosondes

What it covers

Twice a day, at about 800 places around the world, a weather balloon carries a small radio, a radiosonde, to the edge of space. In this video I follow one real flight from the National Weather Service site at Quillayute on the Washington coast, launched by a robot: its climb through the jet stream, the tropopause at minus 59 °C, the warmer air of the ozone layer, the burst at 32 kilometers and the fall toward the Strait of Juan de Fuca, all from its own data. Then why every site launches at the same two moments, what to do if you find one, and how my own station in the Puget Sound hears these flights with the same roof antenna as the aircraft messages, a small radio dongle and the free program radiosonde_auto_rx.

The written guide: set this up yourself

Chapters

  1. 0:00Intro
  2. 1:22The launch
  3. 2:12The radio
  4. 2:52The climb
  5. 3:43The fall
  6. 4:17Why all at once
  7. 4:59My station
  8. 5:41What my station heard
  9. 6:08Intro

Frames from the draft

Radiosondes: Intro
01 Intro
Radiosondes: The launch
02 The launch
Radiosondes: The radio
03 The radio
Radiosondes: The climb
04 The climb
Radiosondes: The fall
05 The fall
Radiosondes: Why all at once
06 Why all at once
Radiosondes: My station
07 My station
Radiosondes: What my station heard
08 What my station heard
Radiosondes: Intro
09 Intro

Gear in this episode

Diamond D-130J discone antennathe wide-band antenna on my roof (25 to 1300 MHz)
RTL-SDR Blog FM band-stop filterthe filter that blocks FM broadcast stations on my wide antenna
Mini-Circuits ZX10-2-12-S+ splitterfeeds two radios from one antenna (mine came from a surplus dealer)
Nooelec NESDR SMArt v5the USB radio I use for radiosondes
Raspberry Pi 5the small computer that runs the decoder
Rosonway RSH-A10 powered USB hubfeeds power and data to the radios on Donatello
Short SMA jumper cablesconnect filter, splitter and radios

Software and references

radiosonde_auto_rxgithub.comthe free decoder my station runs (Project Horus)
SondeHubsondehub.orgthe volunteer network and live map of every sonde in the sky
NWS upper air programweather.govhow and why the Weather Service flies them, and what to do if you find one
University of Wyoming upper-air archiveweather.uwyo.eduevery official sounding, including the flight in this video (station 72797)
RS41nggithub.comfree firmware that turns a found RS41 into a ham radio transmitter

What is simplified, and what is invented

  • The flight is real: NWS Quillayute, 24 October 2026, sonde Y1332547. The climb is the official sounding (University of Wyoming archive), the fall is from SondeHub's public archive, and the part my station heard is from its own decoder log.
  • The drawings of the launch, the sonde, the burst and the find are illustrations of generic scenes. Quillayute launches with an automatic launcher (NWS notice SCN 20-87); the hand launch shows how most of the world's sites do it.
  • The balloon's size in the climb is computed from the sounding's temperature and pressure (the gas law), starting from 1.5 m at launch.
  • The world map shows every upper-air station with data in 2026 in NOAA's IGRA station list.
  • The sonde's sound is made by code from the RS41's real numbers (4800-baud FSK, one 320-byte frame a second); it is not a recording.
  • The coastline is Natural Earth (public domain).