Vaisala RD93 Technical data

Vaisala Dropsonde RD93

www.vaisala.com

The Vaisala Dropsonde RD93 is a
general-purpose, precision dropsonde
meant for high-altitude drops from
high-speed aircraft. It transmits PTU
and wind data at a high data rate.

What is a dropsonde?

The Vaisala Dropsonde RD93 is a
meteorological device that is
launched from an aircraft.
Descending through the atmosphere
by parachute, it measures
atmospheric pressure, temperature,
relative humidity (PTU ) and wind
from the point of launch to the
ground. The RD93 is used with
the Vaisala AVAPS and AVAPS Lite
dropsonde receiving systems. The
RD93 transmits data over a telemetry
link to the onboard receiving system.
The onboard GPS receiver tracks the
dropsonde’s horizontal movement
as it is borne by the wind. The
dropsonde electronics board has a
microprocessor for measuring and
controlling the sensor module and
data transmission. The narrowband
transmitter can be set anywhere in
the 400 MHz meteorological band.

Stable descent

A parachute with a patented square­cone design deploys immediately
upon launch. It slows and stabilizes
the RD93’s descent and ensures that
it does not descend with a pendulum
motion. The rate of descent is
approximately 11 m/s. Mid-sized
and large parachutes, available as
options, provide descent rates of 7
m/s and 5 m/s respectively.

What are the Vaisala
avaps and avaps lite?

The Vaisala AVAPS and AVAPS Lite
systems receive, display and store
the dropsonde data. TheVaisala
AVAPS can track up to four
descending dropsondes at the same
time. This is an essential ability
in weather reconnaissance that is
carried out with high-speed, high­altitude reconnaissance aircraft.

Features/Benefits

For use with Vaisala AVAPS

▪

andAVAPS

Lite dropsonde receiving

▪

systems

Manufactured under license

▪

from NCAR

Widely used since 1997

▪

The Vaisala AVAPS Lite is a receiving
system for receiving data from one
dropsonde at a time. Small and
lightweight, it can be operated with a
laptop PC.

Intellectual property
rightsand development

The Atmospheric Technology
Division (ATD) of the National Center
of Atmospheric Research (NCAR)
developed the hardware and software
for the Vaisala RD93 Dropsonde, the
Vaisala AVAPS and the Vaisala AVAPS
Lite. The hardware and software are
licensed to Vaisala Inc., USA. NCAR/
ATD and Vaisala are committed to
the continuous development of the
AVAPS and AVAPS Lite hardware
and software in accordance with
the evolving requirements of our
customers. Vaisala AVAPS and AVAPS
Lite bring together world-leading
GPS technology and PTU sensor
technology, the results of Vaisala’s
60+ years of expertise in atmospheric
measurement.

Thousands of RD93 dropsondes
are used every year in hurricane
reconnaissance and other
meteorological research projects.

Technical data

Vaisala Dropsonde RD93

Weight < 420 g
Size 7 cm in diameter, 41 cm in length
Maximum deployment airspeed 250 kt IAS (= 125 m/s IAS)
Shelf life 1 year from delivery

Transmitter

Frequency range 400 MHz to 406 MHz
Frequency stability ±3 kHz
RF power output 100 mW
Channel spacing 100 kHz
IF bandwidth 20 kHz
Harmonic & spurious output >50 dB below the carrier level
Total modulation >2.5 kHz, <3.5 kHz
Telemetry range with

325 km
recommended receiving
antenna

GPS Receiver

Type Commercial code-correlating GPS receiver
Channels Tracks up to 8 satellites simultaneously
GPS data downlink 1200 baud, digital
Modulation FSK
Error checking CRC

PTU Modulation

PTU data downlink640 baud, digital
Error checking CRC-16

Temperature sensor

Vaisala THERMOCAP® capacitive bead
Range -90 °C to +60 °C
Resolution 0.1 °C
Accuracy
Repeatability * 0.2 °C
Response time (when used and measured in
Vaisala Radiosonde RS80)
6 m/s, 1000 hPa
< 2 s

Relative humidity sensors

Vaisala H-HUMICAP® thin film capacitor,
heated twin-sensor design
Range 0 % to 100 % RH
Resolution 1 % RH
Accuracy

Repeatability * 2 % RH
Response time (when used and measured in
Vaisala Radiosonde RS92)

6 m/s, 1000 hPa, +20 °C < 0.5 s

6 m/s, 1000 hPa, -40 °C < 20 s

Horizontal winds

Range 0 m/s to 200 m/s
Resolution 0.1 m/s
Wind measurement accuracy 0.5 m/s RMS

Battery

Type Six lithium CR-2 cells in series
Voltage >15 VDC
Current Max. 235 mA, 200 mA average
Life 2 hours (operating), 3 years (shelf)

Pressure sensor

Vaisala BAROCAP® silicon sensor
Range 1080 hPa to 3 hPa
Resolution 0.1 hPa
Accuracy

Repeatability* 0.4 hPa

For more information, visit
www.vaisala.com or contact
us at [e-mail]

Descent

Descent speeds
RD93 ~11 m/s at sea level
RD93M (custom order) ~7 m/s at sea level with optional

mid-size parachute

RD93L (custom order) ~5 m/s at sea level with optional

large parachute

Descent time for RD93

From 14 km ~15 mins

From 7.5 km ~8 mins

*Standard deviation of differences between two

successive repeated calibrations,

k = 2 confidence level

Ref. B210371EN-B ©Vaisala 2009

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