Orolia GSG-5 Series, User Manual With Scpi Manual, Page: 98 / 392

Considerations:
For most L1/L2 GPS receivers, there are two valid configuration modes:
1.
Enable L1 C/A, L1P, and L2P only:
The L1P and L2P will be transmitted without encryption.
2.
Enable L1 C/A, L1P, and L2P, and Pseudo P(Y):
The P code will be scrambled to mimic a realistic P(Y) signal for use in receiv-
ers that can make use of L1/L2 P(Y) signals for codeless applications, or to
provide a signal in the band to better emulate the real world.
In the GSG-6 series, the NAV message transmitted by the GPS satellites is
updated to reflect if (pseudo-) encryption is active or not. This is specified by
bit 19 in the second word of subframe one. This bit represents the anti-spoof
(A-S) flag, where “1” indicates that the A-S mode is on in that satellite. It is
recommended to enable Pseudo P(Y) when the GSG-unit supports it. This will
set the A-S flag to ON which is required in some receivers. GPS receivers may
reject L1CA code if the A-S flag is off.
In GSG-5x units, where it is not possible to transmit Pseudo P(Y), the A-S bit
is always set to ON to indicate that encryption is on (although the actual RF
signal is not transmitted on such units).
The NAV message also holds information on the type of L2 signal being
transmitted (bits 11 and 12 of word three in subframe one). These bits are
always set to indicate that the P code is active on L2.
3.5.10.6 SBAS Satellites
Several GNSS augmentation systems, e.g., differential GPS, exist to further improve pos-
itioning, navigation, and timing functionality (see also:
www.gps.gov ). Space Based Aug-
mentation Systems (SBAS) incorporate system components such as additional SBAS geo
satellites, ground reference stations, and user equipment which together aid the GPS sys-
tem, thereby allowing greater precision and integrity, among other things.
SBAS systems support specific GNSS systems, are available for civil use, and have
been/are being developed for all of the GNSS systems worldwide:
82 User Manual GSG-5/6 Series Rev. 27
3.5 "Select" Menu