A potential customer asked this interesting question.
Most RTK receivers on the market is like Microsoft Powerpoint that has many functions and features yet most customers only use a fraction of its capability. The S100 is designed mainly as a network RTK rover, to be used with your Android phone, stripping out internal 4G cellular modem / UHF radio / color touch LCD display / hot-swappable battery / satellite-based correction service L-band receiver, leveraging NTRIP Internet connectivity of your phone and low-cost smartphone power-bank to improve usage uptime while reducing overall cost.
The internal RTK engine alone, some receivers use large size RTK engine board made of complex circuitry from big brands that was designed years ago and costing over $2000. We use latest state-of-the-art highly-integrated single-chip RTK engine that has much lower cost.
An important fact that an RTK receiver buyer may not be aware of is that: (1) Most RTK correction service around the world are mostly GPS / GLONASS dual-frequency type, some supports additional Galileo, rarely are there full GPS / GLONASS / Galileo / Beidou quad-GNSS dual-frequency ones. Almost none supports additional GPS L5 / Galileo E5a / Beidou B2a on the third 1176.45MHz L5 frequency band. (2) Only common set of signals received by both the base and the rover are used for RTK computation. If the RTK correction service used is GPS / GLONASS dual-frequency only, the additional Galileo / Beidou and L5 capability of the rover goes to waste, it's no different from a GPS / GLONASS dual-frequency rover.
Vermont CORS for Example:
Alabama CORS for Example:
(3) Only when such L1 / L2 / L5 GPS / GLONASS / Galileo / Beidou receivers are used in base/rover pair can the receiver function in full capability. Thus if using the receiver only as a network RTK rover, good to first check what satellite constellations your service provider supports before spending premium price on a L1 / L2 / L5 receiver. Our $499 S100 is a future-proof GPS L1 / L2C, GLONASS L1 / L2, Galileo E1 / E5b, Beidou B1I / B2I quad-GNSS dual-frequency receiver capable of working with quad-GNSS CORS that your service provider ultimately provides.
Other RTK receivers are sold with full-featured RTK Survey software included. The S100 comes with very basic Point Collect and Stakeout feature built into the Polaris Connect App. Customers that finds the built-in feature insufficient, can always use 3rd party App such as Mapit GIS, Mobile Topographer, ESRI ArcGIS Explorer, ESRI ArcGIS Collector, MicroSurvey FieldGenius for Android, Locus GIS,...etc.
The S100 isn't an all-featured RTK receiver with latest bells and whistles, but a handy one for customers that need an affordable network RTK rover. We are very happy to see returning customers ordering additional S100 units after using the first one !