ashtech DG14, Reference Manual

Page: 332 / 390

312 DG14 and DG16 Board & Sensor Reference Manual
SAM: Single Automatic Mode
$PASHS,SBA,SAM
This command sets the DG16 to Single Automatic mode. The demodulated SBAS
data from Channel 1 are used in the navigation solution.
In Single Automatic SBAS mode, the DG16 automatically detects all available
SBAS signals and selects the best ONE satellite, switching automatically as you
move from one coverage area to another. The automatic selection uses both SBAS
channels. Channel 1 tracks the best available SBAS signal and Channel 2 scans
for another available SBAS satellite signals, maintaining a SBAS satellite directory
in a battery-backed memory. The quality of the SBAS satellite tracked on Channel
1 (signal strength, elevation, etc.) is continuously compared to the quality threshold.
When the quality of the signal on Channel 1 is less than the quality threshold, the
DG16 checks the quality of the signal of the Channel 2 satellite. If Channel 2 satellite
has a better signal, the DG16 switches to it. If, on the other hand, the signal on
Channel 1 drops below the threshold and the signal on Channel 2 is no better or
no SBAS satellite, The DG16 continues to use and track the satellite on Channel 1.
The best SBAS satellite is determined based collectively on the satellite SNR, elevation angle,
continuity of signal reception, etc.
SSO: SBAS Satellite Search Order
$PASHS,SBA,SSO,s1[,s2,...]
This command sets the order the receiver searches for SBAS satellites where s1,
s2,... are the SBAS satellite ID numbers ranging from 33 to 64, which are searched
for first. The remaining satellites after the specified SBAS satellites.
The numbers 33 to 64 are used for SBAS satellites. The SBAS system PRN
numbers range from 120 to 138. The offset from SBAS SV ID to SBAS PRN number
is 87. Add 87 to the SV ID to derive the SBAS PRN number.
Example
Enter the following command to set SBAS PRN 122 and 134 as the first in the
search list. SBAS satellite 122 has a satellite ID number 35, and SBAS satellite 134
has a satellite ID number 47.
$PASHS,SBA,SSO,35,47
DEFAULT SETTING
SSO —Search Order Satellite IDs 35, 33, 47, 51, 34, 36, 37, 38, 39, 40, 41,
42, 43, 44, 45, 46, 48, 49, 50