He configurado las opciones avanzadas del GPS FIX de la siguiente manera:
NTP_SERVER=es.pool.ntp.org
XTRA_SERVER_1=http://xtra1.gpsonextra.net/xtra.bin
XTRA_SERVER_2=http://xtra2.gpsonextra.net/xtra.bin
XTRA_SERVER_3=http://xtra3.gpsonextra.net/xtra.bin
# DEBUG LEVELS: 0 - none, 1 - Error, 2 - Warning, 3 - Info
# 4 - Debug, 5 - Verbose
DEBUG_LEVEL =0
# Intermediate position report, 1=enable, 0=disable
INTERMEDIATE_POS=0
# Accuracy threshold for intermediate positions
# less accurate positions are ignored, 0 for passing all positions
ACCURACY_THRES=0
# Report supl ref location as position, 1=enable, 0=disable
REPORT_POSITION_USE_SUPL_REFLOC=1
# Wiper (wifi positioning), 1=enable, 0=disable
ENABLE_WIPER=1
################################
##### AGPS server settings #####
################################
# FOR SUPL SUPPORT, set the following
SUPL_HOST=supl.google.com
SUPL_PORT=7276
SUPL_NO_SECURE_PORT=3425
SUPL_SECURE_PORT=7275
SUPL_TLS_HOST=FQDN
SUPL_TLS_CERT=/etc/SuplRootCert
# FOR C2K PDE SUPPORT, set the following
C2K_HOST=c2k.pde.com
C2K_PORT=1234
CURRENT_CARRIER=common
DEFAULT_AGPS_ENABLE=TRUE
DEFAULT_SSL_ENABLE=FALSE
# TRUE for "User Plane", FALSE for "Control Plane"
DEFAULT_USER_PLANE=TRUE
Lo he copiado de
este enlace de XDA
Un saludo