Outline
This system is an upper-air meteorological observation
instrument which measures a vertical profile of upper-air
atmosphere using a dropsonde. Dropsonde will be
dropped from the aircraft and will transmit temperature,humidity, atmospheric pressure and GPS information on
the carrier wave of the 400 MHz meteorological band.
This system is installed in the aircraft, receives and demodulates this carrier wave, and visually displays transmission data.
MEISEI's dropsonde (iMDS-17) is lighter than the previous dropsonde that measurement can be performed
without parachute. This dropsonde also can be dropped
from the shooter on the air craft since a parachute is nolonger needed.
As of 2017, in Japan, Gulfstream - II (G - Ⅱ) operated
by Diamond Air Service (DAS) is equipped with the drop
sonde receiving system and is contributing to typhoonobservation.

Block diagram
Sonde data

Pre-amplifier

coaxial feedunit

Reveiver
Processor(PC)
ReveiverStorageBox

divider
Reveiver
Processor(PC)

GPS signal
ReveiverStorage
Box

Splitter

Features
●●

●
●

●.

It can receive 4 systems of up to 2 ch × 2 systems.
(The image picture is a 2 ch × 1 line system.)Lighter dropsonde (iMDS - 17) can observe without using a parachute. The risk of observation failure due to deployment of parachute has been minimized.
Soundness of sensors can be confirmed using sonde storage box before observation.
Preparation of dropsonde observation software takes only 5 minutes. Dropsonde data canbe confirmed from observation preparation until the end of observation.
This system can create WMO messages. Output files of this dropsonde are 1-second resolution CSV file and TEMP DROP (FM 37) file.

Observation Software for Dropsonde
Preparation ofObservation screen◎Connection confirmation screen
This screen shows the connection between
the processing PC equipped with observation software and the receiver, and communication between the dropsonde and thesonde storage box.

Pre observation
checking screen

Set dropsonde to storage box◎Sonde sensor check
On the data confirmation screen, software checks
the soundness of the dropsonde based on the predetermined reference value of these parameters:
temperature, humidity, pressure, wind speed, winddirection, altitude, number of GPS satellites, latitude,and longitude.
・Green status means pass, red status means failure.

Observation screen◎Observation screen· On the observation screen, received data is displayedwith numerical value and graphs.
· Data is updated every second.
· The display area of the graph can be changed on thesetting screen.
· Observations can be terminated automatically ormanually.
◎Position
From aircraft
It is calculated by comparing GPS position data of
the aircraft and position data of the dropsonde.
From drop
It is calculated by comparing position of the beginning of observation and position collected fromdropsonde.

Dropsonde（iMDS-17）
Outline●●●The iMDS-17 Dropsonde is a dropped type radiosonde that adopted the latest electronic
components iMS-100 GPS radiosonde.
Due to compactness and weight reduction, it is possible to suppress the descending speed
when it falls without parachute or reduce influence from deployment of parachute. Observation from 12km altitude to the sea level takes approximately 12 minutes.
In the aircraft, after the power is on, this dropsonde will minimize its transmitter power.
Through analysis of pressure from embedded pressure sensor and GPS information, descend can be detected, and the transmitter power will increase automatically.

Temperature

Humidity

Pressure

Geopotential
HeightWindDirection

WindSpeed

GPS Receiver
Descending
speed

Measurement range-90℃ to +50℃

Resolution

0.1℃

Sampling rate

2 Hz

Accuracy*1

Pressure

1050.0 hPa to 3.0 hPa

Temperature-90 ℃ to –60 ℃

Humidity

0 %RH to 100 %RH±0.5 ℃

Tuning range *5400 MHz ～ 406MHz

Response time

< 0.4 s（1,000 hPa, 5 m/s）

Band width< 15 kHzMeasurement range

0%RH to 100%RH

Output power< 100 mW

Resolution

0.1%RH

Transmitter typeFM

Measurement cycle

2 Hz

Modulation type

Digital PCM

Accuracy*1±5%RH

Baud rate

1,200 bps

Response time

< 0.2 s (Absorbing, 1,000 hPa, 6 m/s , 0℃)< 14 s (Absorbing, 1,000 hPa, 6 m/s, -60℃)

Range< 200 kmSampling

1 second

Voltage

3.0 VDC

Current< 300 mA

Battery type

Lithium battery ×１(CR-123)

Operating time> 120 min.

Dimension

Φ 70 mm × 280 mm

Weight

110 g

Measurement range

1050.0 hPa to 3.0 hPa

Resolution

0.1 hPa

Measurement cycle

2 Hz

Accuracy*1± 1 hPa

Response time

<1s

Measurement range-500 m to 4.0,000 m

Resolution

0.1 m

Uncertainty *2 *3

11 m

Measurement range

0 °to 359.99°

Resolution

0.1 °Measurement cycle

1 Hz

Uncertainty *2 *3Surface to 10 hPa: 1 °Measurement range

0 m/s to 200 m/s

Resolution

0.01 m/s

Measurement cycle

1 Hz

Uncertainty* 3 *4

Surface to 10 hPa: 1 m/s

Frequency

1574.25 MHz ±1MHz C/A code

Number of channels

66 parallel channels

Positioning Technology

DGPS (SBAS)

Termination speed

Approximately 13 m/s*1： measurement accuracy at the laboratory*2： Unless otherwise specified, the measurement uncertainty is expressed with the inclusion factor k = 2*3： “PDOP = 1” indicates good GPS positioning*4： Standard deviation (1σ ) evaluated using GPS simulator*5： Frequency can be changed every 100 kHz within specification
range. Please follow the Radio Law for the frequency to use.
※Dimensions exclude antenna (or protrusion)Operatingenvironment

Transmitter

Modulation

PowerOutline view

Dropsonde Receiving System（MDSS） Specification and composition
・Outdoor equipment

・Indoor equipment① Receiving System② Dropsonde storage Box③ Pre-Amplifire④ Observation Software⑤ Dropsonde(iMDS-17)⑥ Antenna

Receiver

Demodulator

Communications

Size ＆ Weight
PowerAntenna

Tuning range

400.0 MHｚ～406.0 MHzOS

Windows 10 64 bit

Channel

100 kHz steps（60 ch）

CPU> 1GHz

Sensitivity< -107 dBm

Memory> 4GBIndicator

Signal strength, Lock lamp

HDD

> 256GB SSD

FunctionsAFC, Limiter AMP, ATT

Type

PCM-FM, Biφ

Baud rate

1200 bps

Error correcting

BCH, 1 bit error correction

Data port

LAN（10/100BASE-T）

Sonde I/F port

D-sub connector

Audio port

Output x 1, Input x 1

Dimensions
Weight320(W)×260(D)×60(H)mm
Approx. 2.0kg

Voltage

100 - 240 VAC (or 12 VDC)

Wattage36 W

Absolute gain

< 1.5 dB

Directionality
Center Frequency
Input impedanceTransmission range

NonData Processor(Laptop PC)> LAN×2 (2 ch receive operation)
Communication> USB × 6
> Serial Port × 1

Size
I/F

17 inchTouch panel

AMP Gain> 7.65 dBi

FilterFc = 404.5MHz

Dimention
Weight300(W)× 120(H) × 400(D) mm
7.0 kgPower15 V (coaxial feed system)

Distribution number4Filter

FC matches the operating freq.

Dimension

350(W)× 80(H) × 300(D) mm50 ΩWeight3.0 kg< 200 kmPowerAC 100V to 240V

405 MHz

Display

Pre-AMPDividerCaution
For safe and correct usage, please read the "Operation
Manual" prior to the use of the products.
● The specifications and appearances might be changed without
prior notice.
● The specifications shown in the catalog are of our standard
products. We are pleased to customize it to meet customer's
requirements. For the details, please contact us.
● Please understand in advance that our company cannot assume
the responsibility of any claims made by the third party about
any monetary damages or any loss of profits arising out from theuse of our products.
● The color of the product photography on catalog might be different from that of actual product due to printing.
MSPA4‐071 M1809

1-1, Toyosu 3-chome,Koto-ku, Tokyo 135-8115, Japan
Tel: +81-3-6204-8254 Fax: +81-3-6204-8888
http://www.meisei.jp/sonde/

The specifications this catalog are current as of September 2018.