Transcript ET-UASI Geneva – 17-20 March 2004 GPSonde M2K2 (WMO Code 56) Patrick CHARPENTIER - Rémy PEPIN MODEM - France.

ET-UASI
Geneva – 17-20 March 2004
GPSonde M2K2
(WMO Code 56)
Patrick CHARPENTIER - Rémy PEPIN
MODEM - France
Design
M2K2 GPSonde (WMO code : 56) is an updated version of the former
GL98 GPSonde. The technology is similar as well and M2K2 design has
been conducted in accordance with the following guide lines :
Research of technical solutions allowing cost reduction



Optimization of electronic design
Reduction of power consomption (4 dry-cells instead of 8)
Reduction of size and weight
Improvement of general performances



More powerfull microprocessor
3 entries for connection of additionnal sensors without interface
Optional buit-in pressure sensor
Avoid any fundamenal change in respect to T and U sensors

New design of sensor boom to prevent eventualdamage during handling
General features
M2K2 GPSonde hold on general specifications from
previous GL98 :

3D GPS board
: Position with latitude, longitude et altitude

Transmitter
: 400-406 MHz synthetizer
Digital data transmission
Narrow bandwidth
Max drift ±2 KHz
200 KHz step frequency setting

Power supply
: 4 dry cells
: Autonomy > 3 h

Factory calibration : Stored on EEPROM
New specifications

Physical features



Electronics optimization


Weight: 210g
Dimensions: 92 x 107 x 160 mm
All functionalities (Transmitter, GPS, microprocessor…) are
implemented on an unique electronic board
High performance microprocessor



Reprogrammable,
3 entries for additional sensors (Ozone, Snow-White,…). No
interface needed for connection
Noise reduction on temperature measurements

New generation 3D GPS board


Power supply



Short initialization time
Significative reduction of energy comsomption
4-battery pack
Optional pressure sensor

On standard version, pressure is calculated from GPS altitude.
M2K2-P version is delivered with a pressure transducer. In this
case, both calculated and measured pressures will be available.
New boom design
The new boom has an
additonnal end leg in
order to better preserve
the balloon in case of
impact with it.
(New
design
is
presented on the left
side).
Temperature sensor
Temperature sensor consists in a thermistor chip wrapped
into a glass ball. Its tiny size (0,9 x 2 mm) allows excellent
response time around 1 to 1,3 sec. Temperature sensor is
led on a layer processed against humidity and solar
radiations.
Boom end is painted with a special white coating to reduce
solar radiation effects.
Temperature sensor details
Humidity sensor

Humidity sensor consists in a capacitor of which
value is directly proportional to relative humidity.
It is composed of 3 primary components :
 Basic
layer as an electrode
 A dielectric of which characteristics vary along
relative humidity
 A short response porous electrode as the second
electrode of the capacitor

A cap is protecting the sensor from rain and
mechanical damage
Humidity sensor improvement
Humidity sensor size is larger
in order to improve response
time.
Former sensor was connected
to the boom through a thin
thread. In order to reduce risk
of dammage, sensor is now
fitted like a surface mounted
component with a metallic
hole in its center.
Original dual-face concept
Hight accuracy
High Haute reliability
Tiny sensor
0% to 100% range
Short response
S
P
S I
Sensor specifications
TEMPERATURE
HUMIDITY
Sensor type
: Thermistance
!
Capacité
Measurement range
: +50° to –90°
!
0% to 100%
Resolution
: 0.1°C
!
0.1%
Absolute accuracy
: +/- 0.5°C
!
+/-5%
Response time
: <2s
!
<2s
Measurement rate
: 1 Hz
!
1 Hz
Factory calibration
:
Stored on EPROM
Calibration prior launch:
Ground check system
GPS specifications
GPS WINDFINDING
General
: DGPS with unlimited altitude - C/A
Position accuracy
: 10 m
Horiz. speed accuracy : 0.15 m/s
Wind dir. accuracy
:2°
Position
: 0.01 m
Horiz. speed resolution : 0.01 m/s
Direction resolution : 0.1 °
Measurement rate
: 1 Hz
PRESSURE
Range
Accuracy
Resolution
: 1050 to 3 hPa
: ±2 hPa at 1050 hPa; ±0.5 hPa at 10 hPa
: 1 hPa at 1050 hPa; 0.1 hPa at 20hPa