DGPS TRIMBLE 4000 SE
DGPS is an enhancement to Global Positioning System that uses a network of fixed ground based reference stations to broadcast the difference between the positions indicated by the satellite systems and the known fixed positions. The position obtained by GPS is not accurate enough for use by DP. The position is improved by use of a fixed ground based reference station (differential station) that compares the GPS position to the known position of the station. The correction is sent to the DGPS receiver by long wave radio frequency. For use in DP an even higher accuracy and reliability is needed.   Overall characteristics of DGPS TRIMBLE 4000 SE
Alimentazione	12 V DC
Memoria interna	> 0.5 MB
Accuratezza orizzontale/vert.	1 cm/2cm + 2x10-6 x baseline
Accuratezza orizzontale:	1 cm + 2x10-6 x baseline
Posizionamento GPS differenziale:
Accuratezza orizzontale:	0.4-0.5 metri RMS
Accuratezza verticale:	1-1.5 metri RMS
Caratteristiche generali:
Tempo di avvio:	meno di 2 minuti dopo l’accensione
Tracking:	9 canali
Intervallo acquisizione dati:	0.5 MB per 18 ore di dati da 5 satelliti
Antenna:	esterna con cavo RG-213 l (30 m)
Rilevamenti statici e dinamici: utilizza il codice C/A solo su frequenza L1