Real-Time Kinematics Explained

[@Sembazuru]

Minor correction... The L-band geosynchronous satellites aren't "somewhere over the southern hemisphere"... Yes, south of you, but it (and all other geosynchronous satellites) orbit over the equator.

[@JonathanBeri]

Great video! Very informative on a subject I've always been curious about.

[@webdeveloperninja9220]

You with Goliath?

[@JonathanBeri]

@@webdeveloperninja9220 yes I am!

[@peterxyz3541]

Great info. I'm researching the difficulty level of including an RTK system in a cinema drone, DIY version of DJI's Inspire. I want to use IR beacons or radio beacons...2 or more beacons. Not sure if DJI use radio or IR triangulation. It's a form of 'digital dolly' for their drone camera moves.

[@byronwatkins2565]

Actually, satellite clocks seem to tick SLOWER due to their relative motion. However, our clocks also tick slower due to our location inside earth's gravitational field. I believe that the gravity effect is about twice as large as the motion effect (though I might have these reversed, the factor of two is quite close). If I have which is largest correct, then the net compensation makes it seem that your misstatement is correct.

[@benargee]

At the end of the day if the deviation is known and constant, compensation is possible.

[@catherinenjeri5637]

This was actually super useful! Do you ship to Kenya?

[@smithbmj]

Enjoyed the video. I do have a question. For Bluetooth applications, can the rover unit be configured for ellipsoidal, geoidal with appropriate geoid model, or orthometric height? Antenna height? Thank you

[@gunningopher]

I've been an RTK user since the mid 90's. I have also set up and operated RTK networks. I am a trainer and on a standards development team for a large state DOT. There is some OK general information here, but I take issue with almost every assertion on this video. It is basically a sales pitch and should be taken as such.

[@tanvach]

Curious what part of the video you disagree with？

[@DustinWill]

Yeah, I’m curious. What assertions? I didn’t catch any. And, re: the sales pitch - did you see what channel this is?

[@KarlLew]

Well, I am here for the sales pitch since this is a Sparkfun video

[@gunningopher]

@@KarlLew So we surveyors have had a saying for a while. What is the difference between a GPS salesperson and a car salesperson? The car sales person knows when they are lying. I'm not saying this guy doesn't know that he is lying, but he is being dishonest non-the-less. Go ahead and lap it up, just know that the claims are bogus and/or misleading, but probably not to a degree that matters to you or his customers (so why do it?). However, saying this is how "RTK Works" instead of "How we use RTK" makes a difference to the wider positioning community.

[@KarlLew]

@@gunningopher I am not comfortable ascribing ill intent to either of you. I would be quite comfortable listening to you about how it works. I am also comfortable listening to a salesperson and deciding not to buy. looking forward to your video. as an engineer watching the progress of gps over my life i am stunned that it can achieve mm accuracy as i learned last week talking to a seismologist. personslly, i look at shadows to see which way to go.

[@jessmac2379]

What's the tiniest RTK module I can attach to a small drone? Also what is its max range?

[@jomfawad9255]

Any plans on making emg sensors with dry electrodes?

[@MrWaalkman]

@7:24 Here's my guess: Punkin Center? What do you have for tracking objects within a building without using satellites?

[@eliz1222]

Can you also explain what’s PPK?

[@New_World_Disorder]

Does it work if there are trees?

[@Flumphinator]

This is *wild*.

[@stagrei8233]

I have a stupid question. Is there a way to use a base station outside and transfer signal inside a building so I can get more precision when I scanning with SLAM technology ?

[@conorstewart2214]

You should have a look at UWB. It doesn’t use GPS but uses a few base stations you would need to set up to calculate the position of a moving module.

[@stagrei8233]

@@conorstewart2214 Thanks, I will look into that.

[@tszabon]

Is there a technology that would enable RTK measurements in dense urban areas and in places surrounded by trees and tall buildings? It would be a great help in my work (architectural visualizations) where we have to accurately and quickly measure points in "difficult" conditions.

[@conorstewart2214]

You could always try using some form of UWB instead. It isn’t linked to GPS but is another method of getting relative positions between anchors (base stations) and a moving module.

[@stephenmackay9762]

How much is the satellite subscription service for the L-Band after the 1 year service ends? Is there a way to get the 14mm accuracy without a subscription service?

[@LrbinMT]

$500 - hopefully that might come down as more people get the Facet l-mode

[@freedomhillbilly348]

@@LrbinMT I was hoping for the same thing. Unfortunately the cost actually went up to $600/yr as of 2024. At that price I held off and am looking into getting a second FACET $700) to use as a Base/Rover. But I really like the idea of setting up my own Reference Station. Here in NH we only have 3 CORS for the whole State.

[@whatthefunction9140]

Why use the ground based stations if there is a satellite...? What am I missing

[@xsk8rat]

I believe, that the satellite is a subscription service, with the first year included with the HW purchase. After which, the subscription service must be renewed.

[@Sembazuru]

In addition to what @xsk8rat says, there are some locations where the portion of the sky (southern sky for us northern hemispherites, northern sky for all those southern hemispherites) where the satellite resides is blocked by mountains, buildings, mountain trolls, your annoying neighbor, etc. This is exacerbated the closer to either pole you get as the location in the sky the satellite is gets closer to the ideal horizon. I don't know how many of those L-band satellites there are around the globe, but there may be some places that there isn't one right overhead and you can't see the next one either to the east or the west of your location.

[@weirdsciencetv4999]

By having a known, fixed position, it can use its own calculated error to compensate for errors introduced by the environment. It’s sending correction data.

[@blakehouchin2304]

Also worth adding is that u-blox PointPerfect correction service for L-Band corrections is currently only available in the USA's 48 contiguous states and Europe.

[@devildogfoxhound1247]

You missed nothing, satellite systems aren’t that accurate.

[@fsn8615]

The prices for what it offers to surveyors are very illogical!

[@gunningopher]

No surveyor should use the equipment shown as it was demonstrated.