"Look! Up in the sky!" "It's a bird!" "It's a plane!" "Aww, shucks!, It's a weather balloon ..."
Yes, it's weather balloon ... strange visitor from another planet, who came to Earth with powers and abilities far beyond those of mortal men! ...
VIZ Sangamo Radiosonde V2 (1987 - never flown)
A radiosonde is a small weather station coupled with a radio transmitter. The radiosonde is attached to helium- or hydrogen-filled balloon, called variously a weather balloon or a sounding balloon, and the balloon lifts the radiosonde to altitudes exceeding 115,000 feet.
During the radiosonde's ascent, it transmits data on temperature, pressure, and humidity to a sea-, air-, or land-based receiving station. Often, the position of the radiosonde is tracked through GPS, radar, or other means, to provide data on the strength and direction of winds aloft. Thus the radiosonde flight produces a vertical profile of weather parameters in the area above which it was launched.
Through international agreement, the 400-to-406 MHz and 1675-to-1700 MHz bands of the electromagnetic spectrum are reserved exclusively for these tiny airborne weather stations to radio their findings back to Earth. The data are processed, correlated with data from other radiosondes, and used to create an instantaneous picture of weather conditions throughout the world. The data are used not only to understand current weather patterns but also as inputs for longer-range computer-based forecasting models.
VIZ Radiosonde SEPCIFICATIONS
TRANSMITTER:- Nominal Frequency: 403 MHz
- Tuning Range: 400-406 MHz
- Output Power (Nominal): 240 mW
- Mode: FM
- Modulation: MFSK
- Type: Continuously variable aneroid
- Measuring Range: 1080 mb to 3 mb
- Accuracy: ±0.5 mb (rms)
- Type: Thin rod thermistor
- Range: -90°C to +60°C
- Accuracy: ±0.2°C (rms)
- Resolution: 0.1°C
- Type: Carbon hygristor
- Range: 5 to 100% RH; +40°C to -50°
- Accuracy: 2% RH (rms)
- Resolution: 1% RH
POWER SOURCE:
- Single water-activated battery
When I get around to it I'll post a schematic (don't hold your breath waiting).
Modern Radiosonde now carry a sophisticated microcontroller electronic package. Receiving weather balloon (Radiosonde) data is easy with a SDR. Everything you need to know and links to software:
Receiving Weather Balloon Data with RTL-SDR
Other Photos of various Radiosonde from: Radiosonde Museum