NS-HP OR NS-HP-GL ?
NS-HP or NS-HP-GL are single frequency RTK receivers. For reliable consistent single-frequency RTK operation, they require 12 or more usable satellite signals above 15 degree elevation angle with SNR no less than 38dB/Hz. With 10 or 11 usable satellite signals, we've seen less than 0.1% rate of getting incorrect RTK Fix off by centimeters ~ decimeters. Fewer the number of usable satellites, longer it takes to get RTK Fix and incorrect RTK Fix probability increases. All single-frequency RTK receivers on the market have similar behavior. The optimal choice is selecting an RTK receiver model that offers greater number of usable satellite signals across 24hr period.
Beidou satellites are not fully operational before 2020. There are abundant of Beidou satellites in Asia, some visibility in Europe, and little visibility in the American continents.
NS-HP is GPS/Beidou type RTK receiver. For users in the American continents, it currently receives very little Beidou signals and behaves like GPS-only RTK receiver (such as the Kickstartered $495 RTK GPS) . NS-HP is intentionally designed to use all available GPS signals and up to 6 Beidou signals, introduced at ultra affordable $50 price for those interested in getting started with RTK technology, not much higher price than normal GPS receiver sold by hobby shops. Standard model that uses all available GPS and Beidou signals is offered at $100.
NS-HP-GL is standard model $100 GPS/GLONASS type RTK receiver using all available GPS and GLONASS signals. Since GLONASS signal has global visibility, NS-HP-GL offers best performance for users outside Asia.
Below figures show number of overhead GPS/Beidou and GPS/GLONASS satellites in different part of the world across 12hr satellite orbit period. One can then easily understand NS-HP or NS-HP-GL can better meet 10 or more usable satellite signals for reliable 24hr RTK operation.
One can easily check overhead satellite situation across the day in his part of the world using GNSS Radar.