"Hi! I am also very interested in this subject but i am lacking the mathematic and programming abilities to pull something off like you did. I think it might be possible to reduce the error if you swap some steps. My postulate: acc/x/y/z are read…"

"Hi Anthony, Iam looking for a solution for my Octocoptor for arial photography and film precise position and lock....I have a flight controller ARM processor also I can add additional processor like Gumstix....ready to buy a good antenna like…"

"> What I don't get is if 2 units are identical and close to each other...would getting DGPS corrections help? DGPS is a low grade correction, slightly better than WAAS as it's localised. RTK is dependant on one of the receivers knowing…"

"Ah. No, I didn't attempt that. This thing had to operate without web connection so even if that would have worked, I didn't look into it. Although I guess it would have been insightful to pinpoint the problem. What I don't get is if…"

"http://en.wikipedia.org/wiki/Networked_Transport_of_RTCM_via_Internet_Protocol NTRIP is a way of getting RTCM messages via the internet http://lefebure.com/software/ntripclient/ have a desktop and a phone app Out of the box, you could feed…"

"Ok, it's been a while since I had my head swirling in GPS. Remind me how NTRIP works? That's a TCP stream with correction data from various ground locations? And that acts as one end of a baseline?"

"It's probably not the antennas that are the issue.  Are you some place where you could establish a baseline using NTRIP? "

"Not really. I never did get better than 3 - 4 meter relative accuracy. I suspect the small patch antennas might be to blame? I tried hooking up 2 identical units to RTKLib and it took forever to a get a lock and it was often wrong.  This might…"

"Did you ever get anywhere with this?"

"Dear Simon Wood, Thx for yours comments. That is right, I am also following RTKLIB releases. I am waiting the version 2.4.2 , especialy (8) Support output of RTCM 2 or 3 I also read some code developed by John Morris about these subject but it…"

"> I need an RTCM encoder Just as a FYI, it looks like RTCM output is planned for the next release of RTKlib. -- For version 2.4.2 (7) Support conversion from receiver raw to RTCM 2 or 3--"

"I agree you can get down to a few cms level with a static receiver and good satelite orientation. I was quoting for a kinetic rover and allowing for some  non optimal satelite orientation. I can supply the Lea-4T developement bare board at…"

"Dear Anthony WooldridgeThank you for your reply.As I have just one u-blox 4T  that is the point, I need an RTCM encoder as my other receiver will be an iQLassen and would be dificult to mix then for RTK application. ( bandwith  and…"

"You can of course use the lea-4T for RTK in RTKlib, you just need to transmit and receive the raw ublox output. Provided of course that both Base and Rover are ublox. The raw ublox output has checksums included, and it does work very well with…"

"Dear Noland. I hope you have it up and running as your question was posted in 2010 . I have an u-blox LEA-4T. By hardware ublox can only accept input of RTCM messages 1,2,3 and 9. Code messages. It would be possible to get centimeter with carrier…"

"Here you go... collected with a survey grade antenna: http://dl.dropbox.com/u/34518077/skytraq.bin"