The Radiosonde DS99 is the continued design of the DS96. The DS96 was well tested in comparison of the worlds manufacturer of Radio weather sondes in 1998 in Lindenberg Observatory of the DWD (German weather forecast).

The new temperature sensor is made of wire - resistor with extreme small diameter. Its surface is high reflective to sun radiation. To make sensing of humidity able below -20°C, the sensor for humidity is a polymer sensor. As a standard there is one temperature sensor and a humidity sensor fitted. Their calibration data are stored non-volatile on the controller unit. The user can easy extend the use of the DS99 with additional sensors.

Via the "set-up - plug" all necessary information of calibration and other sensor data are sent from the DS99 to the receiver system during initializing the system. Transmitters frequency too is sent via this plug from the PC. All information exchange is done automatically by software ADS99. Additional sensors for pressure, ozone and position (GPS)  are available. DS99 is powered by lithium batteries. By using of light weight components (housing made of  Styrofoam) the launching weight of a DS99GPS is below 300gr (including unwinder with 40m balloon cord and batteries).

Radio weather sonde DS99 can be delivered in version:
DS99 Standard version, one sensor for temperature and humidity and 3 spare channels
DS99GPS same as standard version but extended with GPS-module for measuring of position and wind data
Picture of opened Radiosonde DS99

Technical Data
Data transmitting to receiving device
kind of modulation FM, DPSK on subcarrier 2,4kHz
Modulation of subcarrier by software
FM frequency sweep 3 kHz
mode of transmission transmitting in blocks
test for correct data transmission by block parity with error correction
data rate (P, T, U) >1/s
data  rate additional channels >1/s
data rate GPS (Pos, WD, WV, height) 1/s
DPSK= Differential Phase Shift Keying
Technical data of Radio weather sonde DS99
dimensions, weight LxWxH = 93x95x175 mm³
weight without batteries 150 gr.
launching weight with batteries and unwinder
(using T,U,P,GPS – Module)
<300 gr.
quantity of radio sondes in one parcel, total weight 10 pc., with batteries
approx. 3,3 kg
dimensions of parcel LxWxH= 400x300x180mm³
time, ambient temperature, humidity one year, -40°C...+70°C, non condensed
power supply
batteries 3 x 3V lithium sulfur dioxide 
type (single battery) G36 2.1 SAFT
frequency (crystal stabilized, programmable) 402,01 – 405,99 MHz,
by  set up software
adjustment of frequency, channel spacing via software ADS99 during set up, steps of 20kHz according to BAPT 222 ZV 128
transmitter output power typical 100mW at 7VDC
drift of frequency during ascent <5kHz
bandwidth <15kHz
modulation FM, DPSK on subcarrier
transmission ratio <1s  P,T,U
cyclic measuring ration  P,T,U <0,5s
operating time each battery pack (using P,T,U,GPS) >2 h
pressure sensor
sensor aneroid – with strain gauge, temperature compensated
measuring range 1060 - 1 hPa
resolution, range 0.1 hPa, 1 .. 1060 hPa
accuracy,  range <0.5 hPa,  1050 - 5 hPa
temperature sensor 
sensor wire resistor
measuring range -90 .. +50ºC
resolution <0,1K within  –95 .. +60°C
accuracy,  range <0.2K within  -80 .. +40ºC
time constants at
1000 hPa
10 hPa
( on launching speed of  5m/s)

< 1s
< 10s
relative humidity
kind of sensor Polymer, capacitive
resolution 0,1% within 0 .. 105%
measuring range 0 .. 100% relative humidity
(at tamb= -25°C .. +40°C)
±5% within 0 .. 100% relative humidity,
below 0°C until ice saturation
time constants at
(with launching speed of 5m/s)

< 5s
< 40s
sensor 12 channel GPS – receiver with passive patch antenna, adjusted to the same satellites as in the ground station
kind of measuring C/A code correlated GPS
  geogr. width ≤0,001 degree (≤100m)
  geogr. length ≤0,001 degree (≤100m)
  height over normal zero ≤10m @ –400 till  40.000m
@ 40.000 till 50.000m
geogr. width ≤0,001 degree
geogr. length ≤0,001 degree
height over normal zero ≤10m
measuring range height ≤50 km
speed ≤200m/s
wind data
wind speed  
accuracy ±1,0m/s   0..150m/s
resolution ±0,1m/s   0..200m/s
wind direction  
  accuracy >5m/s
  accuracy from >3m/s
  averaging time 30s
±5 degree   0...360 Grad
±10 degree  0... 360 Grad
resolution ±0,5 degree 0... 360 Grad
cycle of measuring position data 1/s
cycle of transferring GPS-data ≤1s
additional channels
channel 1 serial, 16 bit
input level CMOS
channel 2 serial, 16 bit
input level CMOS
channel 3 Analog input 0...5VDC
input resistance 100 kΩ
A/D converter 16 bit
error of linearity , total ±3LSB
gain error ±3LSB
offset error ±8LSB
cycle of transmitting additional channels ≤1s

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