Hybridation de capteurs pour nano-lanceurs

GPS / Inertial Navigation System coupling
Advantages of coupling and general overview of a GPS
•
Structure of a « Sofware GPS Receiver»
RF chain
ADC
•
Acquisition
Signal
processing
Tracking
Hardware
•
Software
Inertial central / GPS coupling
Inertial sensors
(accelerometers
gyrometers)
Inertial navigation
(integration)
Doppler
Estimation
Asset/drawbacks of GPS
+ Good accuracy
+ Constant accuracy once the
target is locked
Perturbations: ionospheric and
tropospheric disturbances,
DOPPLER EFFECT
Possibility of losing signal
Optimized
position
GPS
The inertial navigation system estimates the position, velocity and acceleration of the GPS receiver,
and transmits the information to the tracking software, which will estimate the Doppler frequency.
Tracking unit
Two combined PLL
The tracking software, in order to locate the GPS
receiver, must estimate the carrier signal’s
frequency. If the GPS receiver is moving, there is an
added Doppler effect on the carrier frequency. If
that effect is too important the GPS loses signal.
Once we know the Doppler frequency, we can
include it to the tracking software in order to locate
objects moving with greater acceleration than
before.
Project status
Received signal (GN3S GPS module)
Module de la re pré se nta tion fré que ntie lle
Ré sulta ts d'a cquisition
7
Module (dB)
-60
Signaux non détectés
Signaux détectés
Seuil
-65
6
-70
-75
-3
-2
-1
Signa l GPS Q (duré e : 20 bits CA)
0
Fréquence (MHz)
0
-1
0
3
0.01
0.015
Temps (ms)
Histogra mme (Q)
2
0
-4
-2
0
Classe
2
0
0.005
0.01
0.015
Temps (ms)
Histogra mme (I)
5
Nombre par classe
x 10
4
4
x 10
4
3
2
1
2
0
-4
5
4
0
-1
0.005
5
4
2
1
Amplitude
Amplitude
1
1
Signa l GPS I (duré e : 20 bits CA)
Métrique d'acquisition
-4
Nombre par classe
1.Use Doppler estimation to help
Tracking (PLL)
2.GPS raw data simulator
3.Doppler estimation
4.SiGe GN3S GPS module (v3)
Satellites detection results
-2
0
Classe
2
4
0
0
Khalid ES SAADI – Qi XU
PERSEUS Seminary– 2 fev-4 fev 2012
5
10
15
N° satellite
20
25
30