I’m new to RTK. Can anyone point me to where I can learn about finding an appropriate NTRIP caster that is free or very low cost? I need something compatible with “RTCM 3.1” I need to do some testing in Washington State USA. I’m not even clear if you have to select a regional NTRIP caster within a certain distance?
Thanks in advance for any help.
www.rtk2go.com works well, just make sure you follow the instructions on the website. for the base, you can set your mountpoint to have a password or not. when you put in the ntrip settings, if you decided to password protect your mountpoint, you only put the password in ON THE BASE. for the rover, you DO NOT need to put that password in. if you do not opt to password protect your mountpoint then you dont need to worry about a password at all. the other service would be youcors. I have not used youcors but others here have.
I’m actually inquiring from the aspect of being a client not a caster. Since posting I gathered a bit more info and actually did discover SNIP and RTK2GO there appears to be no other significant networks of free NTRIP casters. Unfortunately the network is very thin, not a lot of good geographic coverage. I got very very lucky and there just happened to be a caster very close to be where I’m testing and only one other caster in the entire state.
It appears Trimbal VRSNow is probably the closest thing but it has a significant subscription fee. There is also a correction network run by the public utilities in my state but at $1,900 a year, that’s not in my budget. So it appears in many cases if you need centimeter level accuracy, you would most likely have to use PPK with CORS data in the absence of a free nearby NTRIP caster.
I am guesssing the corrections are less effective the farther from the base station that is casting, but could you still use a far away caster (like 700 km / 500 miles?) to get the position accuracy a lot better than the 1-3m accuracy you get with typical GPS receiver? Would it be like 10-20cm accuracy instead of 2-5cm you’d get from a closer station? How can you estimate?
I think in this instance, you would probably be better served getting a base to go with your rover if you are looking for better accuracy. I have found a base+rover, ties to GPS and least square adjustments get me down to hundreths which is frankly amazing for the cost of this hardware. If you dont have access to GPS ties in your area of work, then I can see how needing a VRS sub may be the only choice. I just dont see a way around your issue without setting up your own base even to provide the NTRIP info because you are going to need a solid and accurate point to cast to others/yourself.
My bad if this info is not helpful, I am a licensed surveyor in cali so my point of reference may be way different than what you are attempting to do.
The application is actually for a drone. If I have a known point, I can use the base station. If I don’t have a known point the remote controller for the drone allows for an NTRIP connection so the remote serves as the conduit between the remote VRS caster (which I think is basically my ‘virtual’ base station) and the drone. I just tested with the closest caster which is 140 miles away right now but will be less than 5 miles when I get to the site. The connection is FLOAT and the drone software will not let me fly due to “weak RTK signal” I’m not sure if that is due to the 4G mobile data connection I’m testing, inconsistency with the caster’s network broadcast (not fast enough casting or breaks in the connection), or just because I’m so far away. Guess I’ll find out tomorrow when I get to the test site.
Here in Ohio, I use the Ohio CORS network and a M2/RS2 with NTRIP. Washington has a network as well. Here is their link Washington State Reference Network - Sensor Map
I didn’t research their site that well but if it is like Ohio, you have to create an account, get a Username/password then you can connect no charge. Some states do charge.
Most have multiple streams CMR/RTCM2.X/RTCM3.X and the same streams utilizing GLONASS. The NTRIP server and client should be using the same satellite constellations. It the server only uses GPS/GLONASS and your receiver has GPS/GLONASS/QZSS/BeiDou/Galileo the last three really are not doing anything for you.
Sorry, I just dug into their site deeper and found they are a pay for subscription.
There is another pay for service, DigiFarm, but they only have two towers in Washington state so far. Perhaps you could contact them and become a 3rd location for them. I believe they have reduced rates for those that host a base station.
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