I recently recieved a Phantom 4 RTK along with a D-RTK Mobile station. When using the tablet that is built into the controller I am unable to set the correct latitude and longitude for the D-RTK Mobile station. When  inputting the latitude/longitude I am unable to add a negative sign. It  is right on the keypad, however when I press it, it does not appear on  the screen. I have also tried typing this coordinate out in another app and copying and pasting it in. However upon pasting the coordinate into the DJI GS, the negative sign disapears. This seems like a bug in the app, however it also seems way too large  to have been overlooked during testing. This is a very important feature to have working correctly. Without it, RTK flight data is worthless in the entire western hemisphere.

Here are some images of the problem

You will be lucky to get an answer here. The DJI Moderators are not technical, and it is very unlikely that anyone on here knows anything about the RTK. Best to try and find a furum that specialises in the
RTK model.

With regard to the entry, have you tried using the compass points notation? It is an alternative method, as in 35.66N or 35.66S ?

I haven't received my base yet but I suspect Geebax's answer might be the correct one. It's really common in some programs to no understand the negative but instead key on N or E. You might also try them as a leading character.

Are you certain you have the correct coordinate system setup for the base station?

I've seen the same issue and there is no alpha keyboard to enter W for the negative Longitude. For now I've either used the Cell base system or just accepted the values calculated by the base and move the data later using the end orthomosaic. It's a bug. One of many that I've been seeing. I am curious whether the update that I see mention of will fix it but so far haven't found a way to do so. Frankly the cryptic error messages combined with an overall lack of polish is worrisome. It desperately needs a good native speaking product manager to run through actual usage and fix some of it.

MTCWBY Posted at 1-3 17:19
I've seen the same issue and there is no alpha keyboard to enter W for the negative Longitude. For now I've either used the Cell base system or just accepted the values calculated by the base and move the data later using the end orthomosaic. It's a bug. One of many that I've been seeing. I am curious whether the update that I see mention of will fix it but so far haven't found a way to do so. Frankly the cryptic error messages combined with an overall lack of polish is worrisome. It desperately needs a good native speaking product manager to run through actual usage and fix some of it.

this issue was fixed with the 5 dec 2018 firmware update.. hope this helps..

fanscb9357c3 Posted at 1-6 17:36
this issue was fixed with the 5 dec 2018 firmware update.. hope this helps..

It would be nice if they rolled that update to everyone. I get doing graduated rolls of software as we do it ourselves but that goes out the window when you have major bugs like this one and the inability to enter authorizations to fly in certain airspace.

They've fixed it with the latest update and I've tested it twice. There are still bugs but they can be worked around. It will not save the values you type in unless they are close enough and there is confirmation if it accepts them. I had hoped that like many bases, the values set in the base would be remembered if close but it does not do that. What it does do is leave your last values in the GNSS coordinate setting so you can just press settings again. I was fine with that except it doesn't actually do it unless you change the lat or long slightly. I ended up just adding a zero and then it reset the base. And of course the app broke reflying saved flights with this version so a couple steps forward and another back. It also has a nice cryptic message when you try to authorize about the system changing.

The 50m tolerance needs to be removed. Many of use work with control set by other sources so we have to go with whatever they gives us or have the ability to localize to it. That would be the best solution for this setup. Let the base collect whatever coordinate it wants and then measure and localize each control point you have info for. The other problem this solves is that your data will then be on your local site coordinates. I don't know if this is just something that we do in the US or what, but there are a ton of companies out there with amazing products that don't allow for localization.