ho_tom2333 wrote: ↑Thu Jan 13, 2022 7:08 am
Do I need to register for account before using RTK in my country? I am in Hong Kong
Free RTK Sign Up:
Doing a little Google searching, here is the website for the [free] RTK NTRIP correction service in Hong Kong. Many places in the world have one available, sometimes for free. For example, there are similar free services in many parts of the United States. This website has the application form to get a free userId as well as the hostname and port for the service:
I don't know China or HK law, though may be important for you to:
It's worth as other repliers mentioned becoming familiar with the laws and customs in your jurisdictions. I'm not familiar with the current status of the special relationship between the rest of the mainland China and Hong Kong. I do know of scientist friends doing archeology who were questioned for having accurate GPS equipment in 2014. Certainly anything unusual will draw attention. And I am unfamiliar with the current status or exact details of Chinas GPS and map policies, though I know they have in the recent past required map providers to scramble locations a bit. Two points from that (1) they are sensitive to potential misuse of mapping that might make the country less secure. (2) China and possibly Hong Kong could have laws that you need to be aware of. I don't know what they are. I suspect the website above might link you to the information or to folk who know that information.
Happy RTKing. I hope it goes well.
Yes, you need a source for local RTK corrections to use RTK:
Oh, to answer your question, you need a live RTK data stream to get the corrections to lock on to DGPS and then to use that and carrier phase information to perform corrections. The link above is to the Hong Kong version. RTK is a special kind of correction, and most GPS receivers don't have that capability. Only those listed as RTK, which SparkFun has several. I'm currently debating between the F9P and F9K kits. You would also need a few other parts which they list in the 'wish list' in the instructions page. Even though the instructions are very detailed, if you do not have some electronics and programming background, I think it will be harder to do things for the first time. Though if you like electronics as a hobby, you probably like a challenge.
try to explain RTK some:
The RTK data stream has a collection of ground reference stations in your area near you that are constantly taking measurements. Satellites are broadcasting their orbits with rough corrections so that your GPS can tell where you are at a point in time and space, using the differences from at least 4 satellites. The satellites are not broadcasting very fast or very local corrections for things like weather near the ground or ionic weather in space. So, each station is measuring to millimeter magnitude what is the difference between where each satellite is saying the reference station is located and the well known, not moving at all location of the station. From a grid of several ground stations nearby, the RTK system can interpolate those corrections at different points on the ground to give you a very good improvement on the position of your GPS/GNSS antenna.
What's in a name:
Technically GPS only refers to the constellation from the USA. GPS, Beidou, Glonass, and Galileo are all examples of what is called GNSS for Global navigation Satellite System. However many people use GPS to refer to any of those, so don't get confused. Many receivers now can combine information from several of these constellations at once to achieve better reliability and accuracy than one constellation alone. RTK gets you more than 10 times closer in accuracy.
I hope that's helpful.