iSXblue/SXBlue II GNSS Series Technical Reference Manual
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2. Features and Performance
This chapter provides an introduction to some of the iSXBlue/SXBlue II Series high-level features. The
remaining chapters provide more detailed information on the workings of the product.
As mentioned in the previous chapter, if you are new to GPS, SBAS, DGPS, RTK corrections, we
recommend that you consult Appendix C for further information on these services and technologies.
When powered for the first time, the iSXBlue/SXBlue II will perform a ‘cold start’, which involves
acquiring the available GPS/GNSS satellites in view and the default differential service.
If you choose to use an external source of RTCM SC-104 correction data, you will need to ensure that the
external source supports an eight data bit, no parity, and one stop bit configuration (8-N-1) and a baud
rate between 4800 and 230400 baud.
This chapter describes the various modes of operation and features of your iSXblue/SXBlue II receiver.
2.1
GPS
The following sections describe the general operation of the iSXBlue/SXBlue II receiver running the
MFA (Multi-Function Application firmware).
2.1.1
Satellite Tracking
The iSXBlue/SXBlue II automatically searches for GPS satellites, acquires the signal, and manages the
associated navigation information required for positioning and tracking. This is a hands-free mode of
operation. Satellite acquisition quality is described as a signal to noise ratio (SNR). A higher SNR is
indicative of better quality signal reception. For the GNSS models, GLONASS satellites are tracked, but
used only in the solution when either GPS-only (see G-DIF and Suretrack features in Section 2.5 below)
or GNSS differential correction is available. The receiver can be forced to use GLONASS in non-
differential mode by setting the differential input to none: $JDIFF, NONE
Note – The GPS engine is always operating, regardless of the DGPS mode of operation.
2.1.2
Positioning Accuracy
The iSXBlue/SXBlue II GNSS is a sub-meter (horizontally), 95% accurate product under ideal conditions
(minimum error) when using code-phase, submeter when using RTK, decimeter when using OmniSTAR
HP and G2 services and sub-centimeter when used in post-processing.
Keeping in mind that this horizontal performance specification is a real world but ideal scenario test,
obstruction of satellites, multipath signals from reflective objects, and operating with poor corrections
will detract from the receiver’s ability to provide accurate reliable positions. Submeter differential
performance can also be compromised if the iSXBlue/SXBlue II GNSS is using SBAS in a region
without sufficient ionospheric map coverage. If external corrections are used, the baseline separation
between the remote and base station antennas can affect performance.
Since the iSXBlue/SXBlue II GNSS will be used sometimes in harsh conditions, blockage of the line of
sight to SBAS satellites is often inevitable. The COAST technology provides solace from obstruction of
