P306/P307 Integrator’s Guide
Appendix A-Frequently Asked Questions
Page 30 of 39
contained in the $GPGGA message. Additionally, the P306/P307 has surface-mounted status
LEDs that indicate receiver status.
SBAS Reception and Performance
How do I know if the P306/P307 has acquired an SBAS signal?
The P306/P307 outputs the $RD1 message that contains the SBAS Bit Error Rate (BER) for each
SBAS channel. The BER value describes the rate of errors received from SBAS. Ideally, this
should be zero. However, the P306/P307 performs well up to 150 BER. The SLXMon and
PocketMax3 utilities provide this information without needing to use NMEA commands.
How do I know if the P306/P307 is offering a differentially-corrected or RTK-corrected
position?
The P306/P307 outputs the $GPGGA message as the main positioning data message. This
message contains a quality indicator fix value that describes the GNSS position status.. The
SLXMon and PocketMax3™ utilities provide this information without needing to use NMEA
commands.
Quality Indicator
(Value)
GNSS Position Status
2
DGPS
5
RTK Float
4
RTK Fix
How do I select an SBAS satellite?
By default, the P306/P307 will automatically attempt to track the appropriate SBAS satellites. If
multiple satellites are available, the one with the lowest BER value is selected to be used to
decode the corrections.
You can manually select which SBAS satellites to track—refer to the
Hemisphere GNSS Technical
Reference
; however, this is not recommended.
Should I be concerned if the P306/P307 is frequently losing lock on SBAS due to
obstructions or low satellite elevation angles at my geographic location?
No, provided the receiver is receiving a full set of corrections relatively often. Using COAST
technology, the P306/P307 is able to perform well for 40 minutes or more with aging correction
data. Similar to DGPS corrections, accuracy degrades over time and distance. To obtain a full set
of corrections the P306/P307 antenna receives the ionospheric map over a period of a few
minutes. This is the minimum amount of time required to get a full set of corrections for SBAS
operation. After this, the receiver can coast until the next set of corrections have been received.
Accuracy is a function of correction age and current ionospheric activity, which will increase in the
coming years.
Do I need a dual frequency antenna for SBAS?
Summary of Contents for P306
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