Tianbao is a high-end product in GPS, which is 1 in the industry, but the price is also the most expensive. (But Tianbao's total station is not sold much in China. )
Leica's GPS hardware does not have its own technology, the antenna is OEM, the GPS motherboard is OEM Novatel, and only the measurement software is developed by Leica itself. Therefore, the price of Leica has no advantage, and the product quality is subject to OEM manufacturers. Leica's gps is the most difficult and complicated to use among imported brands (but its total station is the best in the world).
Topcon didn't have the core technology of GPS at first. In 2000, Topcon acquired JAVAD, the authoritative GPS service provider.
However, Topcon was separated from JAVAD and established Topcon Positioning System Company (TPS Company) in the United States, which absorbed all the research and development teams of JAVAD, including two teams from the United States and Russia. Specializing in GPS measurement products; Topcon GPS sold in the market now, its core board is developed by TPS company, not JAVAD；; JAVAD has its own R&D team, and the main market of its GPS products is still abroad, and its popularity in China is not high. At present, almost no unit in China uses JAVAD products.
Since 2000, Pentax Japan has shifted its focus to the research and development of positioning measurement technology. It cooperates with Novatec GPS motherboard and carlson, the most prestigious measurement software supplier in the United States, to develop GPS measurement software. Coincidentally, Pentax and JAVAD also announced the establishment of a product strategic alliance in Tokyo, Japan in September 2007, and worked closely with each other to develop a new generation of geographic data systems. Pentax will integrate JAVAD's technology and experience in GNSS into product design, gather high-end survey professionals around the world and develop the best quality products. At present, Pentax has launched several surveying GNSS such as SMART 8800 and SMT888-3G, among which SMT888-3G integrated with GPS/GLONASS/ Galileo was launched worldwide in 2009. The precision of static post-processing has reached the highest (2mm+0.5ppm 5mm+0.5ppm) in GNSS measurement at present.
In recent years, Japanese GPS such as Pentax has been known for its high cost performance. If your company has money, please buy Tianbao. If your company has limited funds and wants to buy products with high stability, please buy Pentax or Topcon. If your company is short of funds and wants to use GPS RTK for survey, please purchase the survey in South China, China Haida or China. At present, domestic GPS products have greatly improved in radio communication, but there is still a certain gap compared with imported products.
Magellan and Gao Ming mainly do hand-held GPS and car GPS.
Huace, China Haida specializes in GPS, and China Haida's sounding products are good.
In short, buying GPS is not about performance, but about service. You can buy any good service.
The above are personal opinions and are for reference only;