Hybridation de capteurs pour nano-lanceurs
Transcription
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