TinkerRTK is less expensive than competing options in part due to choosing SkyTraq receivers rather than u-blox receivers. TinkerRTK is available with SkyTraq PX1125R and PX1122R receivers. Other RTK solutions typically use the u-blox ZED-F9P receiver. Here we will look at the specs for these receivers.
First, an important element of RTK performance is the number of satellites that are going to be visible at any given time. Having more available satellites allows faster and more robust RTK solutions, as well as permitting solutions where portions of the sky are blocked. Below is a table with the bands supported by each receiver as well as the approximate number of satellites that use each band, note that NavIC is a regional system operated by India.
The PX1122R covers the same bands as the u-blox ZED-F9P while the PX1125R does not cover the L2 bands, but does cover bands that the PX1122R and ZED-F9P do not cover with a similar number of global satellites.
Some additional important specs for the three receivers are in the table below. The three receivers have comparable RTK accuracy, update rates, and cold start/RTK convergence times.