iMet-54 Radiosonde

The iMet-54 is a new-generation radiosonde utilising the latest in sensor technologies. Improved measurement techniques help to overcome previous limitations such as evaporative-cooling of the temperature sensor and humidity sensor icing. The simple, intuitive user interface makes sounding preparations easy. A sophisticated error correction transmission scheme guarantees a reliable data link in the most challenging urban environments.

Key Features
- Capacitive thin-film polymer humidity sensor with integrated heater for fast response at low temperature
- Dynamic heating of the humidity sensor prevents saturation or ice formation on the sensor.
- A very small mass glass bead thermistor facilitates extremely fast response to temperature changes. Reflective coating reduces the effects of solar radiation while a hydrophobic polymer counters evaporative cooling events
- SI traceable sensor calibration
- High sensitivity, multi-constellation GNSS receiver with unparalleled accuracy of wind and altitude measurement
- ETSI certified telemetry transmitter provides error free data transmission without interference. Forward-error correcting techniques ensure fault correction for a highly robust telemetry link
- Pre-installed dry lithium battery. Easy-to-use push-button controls power and pre-set transmission frequencies
- User-selectable transmission frequency anywhere within the assigned meteorological frequency band
- No pre-flight recalibration required – all sensors are factory calibrated
- Compact and light weight: 235 x 70 x 30 mm and only 80 grams
- Reduced environmental impact

System overview

Battery	Lithium
Operating time	> 180 min
Dimensions (L x W x H)	235 x 70 x 30 mm
Weight	80 g
Calibration Stability	2 years
Power control	Wireless or Push button

GPS Receiver

Type	GNSS
Channels	99 Channels
GNNS Systems	GPS + GLONASS
Cold Start Acquisition Time	35 s (nominal)
Reacquisition Time	1 s (nominal)
Horizontal Position Accuracy	2.5 m (CEP)

Humidity

Type	Capacitive Thin Polymer
Range	0 % to 100 % RH
Resolution	0.01 % RH
Response Time
6 m/s, 1000 hPa, +20°C	< 0.4 s
6 m/s, 1000 hPa, 0°C	< 1 s
6 m/s, 1000 hPa, – 20°C	< 3.2 s
6 m/s, 1000 hPa, -40°C	< 20 s
Repeatability in Calibration	< 2 % RH
Uncertainty	< 4 % RH
Reproducibility	< 3 % RH

Temperature

Type	Bead Thermistor
Range	-100 °C to + 60°C
Resolution	0.01 °C
Response time (still air @ 1000 hPa)	< 2 s
Response time (6 m/s flow @ 1000 hPa)	< 0.5 s
Repeatability in Calibration	< 0.1 °C
Uncertainty > 100 hPa	< 0.3 °C
Uncertainty < 100 hPa	< 0.5 °C
Reproducibility > 100 hPa	< 0.1 °C
Reproducibility < 100 hPa	< 0.25 °C

Pressure (GNSS derived)

Type	GNSS derived
Range	1100 to 3 hPa
Resolution	<0.01 hPa
Uncertainty: 1100 – 400 hPa	< 1 hPa
Uncertainty: 400 – 100 hPa	< 0.4 hPa
Uncertainty: 100 – 3 hPa	< 0.2 hPa
Reproducibility: 1100 – 400 hPa	< 0.6 hPa
Reproducibility: 400 – 100 hPa	< 0.3 hPa
Reproducibility: 100 – 3 hPa	< 0.2 hPa

Telemetry

Transmission type	Synthesized
Maximum range	>250 km
Frequency band	400.15 – 406 MHz OR 1668.4 – 1690 MHz
Frequency stability	±2 kHz
Deviation (peak to peak)	4.8 kHz
Output power	200 mW
Emission Bandwidth	According to EN 302 054 for 403MHz model According to EN 302 454 for 1680MHz model
Sideband Radiation	According to EN 302 054 for 403MHz model According to EN 302 454 for 1680MHz model
Modulation	GFSK
Data rate	4800 bit/s
Frequency selection	Wireless or push button
Push button frequencies	402, 403, 404, 405 MHz OR 1676, 1678, 1680, 1682 MHz
Wireless frequency selection	400 – 406 MHz (10 kHz resolution) OR 1668.4 – 1690MHz (10kHz resolution)

Wind

Type	GNSS derived
Wind Speed Range	0 to 180 m/s
Wind Speed Resolution	0.1 m/s
Wind Speed Uncertainty	< 0.15 m/s
Wind Speed Reproducibility	< 0.1 m/s
Wind Direction Range	0 to 360°
Wind Direction Resolution	0.01°
Wind Direction Uncertainty	< 1°
Wind Direction Reproducibility	< 1°

Geopotential Height

Type	GNSS derived or optional Piezoresistive Sensor
Range	0 to 50 km
Resolution	0.1m
Uncertainty	< 8m
Reproducibility	< 5m

Ordering Information

Documents

iMet-P

iMet-P Pilotsonde

iMet-54 Research Sonde

iMet-54 Research Radiosonde

iMet-50 GPS Pilotsonde

iMet-50 Pilotsonde