Dear friends, I would like to introduce you the RTKite GNSS RTK L1+L2 module receiver.
http://northsurveying.com/index.php/instruments/gnss-rtk-receiver
Designed specifically for Pro and Semi-pro UAV, Robotics and Industrial applications, it connects directly to the Pixhawk and other autopilots and is specific for millimetric Photogrammetry, LIDAR Scans, Themography, etc.
The RTKite is a full Receiver (not a basic GNSS board) with an internal OS that can connect directly to standard CORS stations with its embedded GSM/GPRS cellular modem, can be configured and operated by Bluetooth, COM or TTL communications and can be set with our freeware for Android, Windows PC or WindCE or Linux, or even with text string commands.
It also can receive and transmit RTCM or CRM correction signals by UHF radio or our unique AutoCaster system that allows direct link connection by the integrated mobile modem with an stable transmission range of 75Km on Fixed position.
In is in fact a miniaturization of our professional surveying RTK receiver SmaRTK, (first generation released on 2012), and is compatible with our unique AutoCaster system for direct Base to Rover cellular data link.
Below, an Autocaster test on a modified DJI drone with Pixhawk and the RTKite GNSS with the lightweight helical antenna.
Comments
@Darius, Now I get your meaning of "2D navigation" however that is only on the frontend towards non-professional users. Internally there is no other navigation than 3D, for the reasons I've already exposed.
A point that has not been mentioned and probably is the origin of the confusion is the hysteresis or "gauss-smooth" that consumer grade receivers do, to avoid people to think their receiver are jumping 3m in 1 second. This is done by the Ublox, Garmins, etc., and we have reviewed that is being done on the 3DR L1 receiver as well. In RTK this is not used and the position are always raw from the RTK solver.
Regarding your CORS project, of course we do supply CORS receivers and fixed or choke-ring antennas. There are two main ways, one is the classical Server+NTRIP software+Receiver or our AutoCaster, that does not need a server or NTRIP but connects direct to the said CORS receiver by mobile network or fixed IP.
Regarding legislation, as far as you do not use radio broadcast, and use only internet, there is nothing to ask permission for.
The Autocaster system is free and do not uses passwords, so has free access for IP broadcast and is the simplest way to set it up and running in 5 minutes. You can use an NTRIP software but it is not needed for 1 base standalone. What do you loose? Potential VRS, but if you ever need that you could always switch.
Please write to emea@northgps.com to have an access to the detailed list.
Good day Darius
I will gladly provide you a unit.
I have setup a CORS system in Namibia as there is no CORS system there. My brother is a professional land surveyor there. Initially we it was for our own use but we have given everyone access to the system.
What I did was to use point to multi point cellular routers, the local cellular service provider created an APN for us and provided us with static IP addresses for the routers.
Unlike the local CORS system that has been down for the last 4 days preventing from logging data and posting it here the system in Namobia has been up for just over 3 years with zero downtime.
I will let you know exactly what is happening after my meeting with the university tomorrow.
They are looking at producing the units as well as further development of the units.
Regards
Anton
@Bernardo,
thank you for your excellent input.
What I mean by 2D navigation is GPS car navigation,
2D GPS marine navigation.
What I mean by 3D GPS navigation is drone flying in 3D space.
I would like to set up first Open CORS (open to the public) GNSS RTK reference station,
public funded personally.
Could you deliver your L1/L2 RTK receiver/transmitter kit + antenna
and at what cost ?
@Anton,
could you deliver your L1 RTK receiver/transmitter kit with antenna to set up
Open CORS reference station, public CORS station providing open, unrestricted access 24h on the private ground ?
If you are aware of EU legislation to control operation, set up of such Open CORS GPS RTK reference station, please let me know.
I am interested to develop Open CORS stations at Open FabLab.
Just free, open access, no registration since RTK GPS corrections on open IP brodcast channel.
BTW
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Users
The EPN real-time GNSS data streams can be downloaded from the EPN regional broadcasters using a free Ntrip client software (available for several platforms).
Each broadcaster will request that you first complete a user registration to grant you the authorization (user-ID and password) to access the EPN streams they provide: User registration for ASI (Italy), BKG (Germany) and ROB (Belgium). Click here to have an overview of the streams presently available from each broadcaster and here for some station operation details generated by the BKG broadcaster.
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@Martin, thanks but Its ok, we have 10 years on the GNSS RTK field and know that many concepts have been artificially obscured.
Our policy is all windows open, and we will try to clarify as much as possible and every time.
@Bernardo, I have a little tip for you that might save you some time. Take a look at Darius' posts in other threads.
@Darius
From "I am really sorry but CORS grid is highly dense today so you easily reduce your baseline from 1000km to 100km." This is exacty my point (if you consider USA, Europe and countries with CORS course) So I don't understand where do you disagree. And anyway you always can use a nearby (yours) RTK Base on the ground.
Bottomline is Long base lines are not needed and should be avoided. They are caused by economy, not technology.
Regarding all you 2D comments, I'm sorry to disagree. Earth is 3D and Geoidal and so do all the geodetic dimensions. If you really would be navigating in 2D, before 100km straight you would reach the stratosphere, just do Pythagoras to check.
Mean Sea Level change every year and has to be adjusted by local charts (http://www.esri.com/news/arcuser/0703/geoid1of3.html), so it is not a fixed reference. Ground levels drift with tectonic movement, so that is also corrected from time to time.
The output rate, as commented and if you see the datasheet (http://northsurveying.com/index.php/instruments/gnss-rtk-receiver), it is 150Hz. Also we have set a robotic capture application working at 450Hz, with the same RTKite receiver it only needs a fast enough hardware on the other side to be able to read it.
Ublox is consumer of course. We are not talking of consumer electronics. This blog is for professional uses.
Europe has free CORS coverage in many areas, we are using one, please check it may help your project: http://www.epncb.oma.be/
In Barcelona the open and free network is here, used by everyone hobbyist or otherwise, just need to ask: http://catnet-ip.icc.cat/
Fly away can be originated by many causes not related to GPS, as uncorrected receiver L1 can give 3.5m and with any SBAS would be 1.5m. An L1+L2 with SBAS would have 0.3-0.5m accuracy non-RTK. Interference otherwise can easily completely cut off any satellite signal, RF and even mess with IMU and AutoPilot. Common sources are Electric transmission lines, TV and Cellphone towers and static charged clouds i.e. black clouds.
That is a critical area that is solved with the antijamming GNSS systems used on tactical warheads, but a bit too heavy for small drones, besides expensive.
I recommend you this ESA company, has already a solution for high accuracy L1 solution method and have a great implementation that you may want to try: http://www.rokubun.cat/
As a side comment, it is OK for you to say that a scientific publication is not valid or applicable, but to be constructive you should tell why not, and much better if you do show some data that is then useful on your point of view so to review it as well.
@Bernardo,
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Indeed my problem is on a claim of fast moving RTK solution fixed with a baseline > 1000Km and high accuracy at the same time. I've never seen that in the wild and the papers shown are examples to illustrate my own field experience with any kind of receiver. "
I am really sorry but CORS grid is highly dense today so you easily reduce your baseline from 1000km to 100km.
Surveying is static and 2D in that sense that your drone flies in AltHold mode (fixed altitude) and images shot are 2D.
Marine GNSS is either 2D sea-level navigation.
Drone GPS Rover is the only fast moving, fast flying object (aircraft) in 3D space and CORS grid was not build to serve this purpose ( GPS err in altitude).
What do you mean by fast clocked receiver ?
Can you make your GNSS GPS chip to be clocked 50Hz, 100Hz, 150Hz
to geet fix updated at 50Hz, 100Hz, 150Hz ?
Such technology is not offered by Ublox, not being offered by others.
I read research papers links by you and none is relevant to precision flying by personal drone.
I have ready project to build public network of CORS reference stations all-over the Europe to provide RTK corrections on free basis via Internet (or flat rated).
As I am aware, ESA is not involved in the study of CMEs, Space Weather, Jet Streams,
to build real-time, reliable GPS ionospheric, tropospheric error maps and frankly speakingI am no surprised since EU-based network of CORS ground reference stations is dense but access restricted, closed to hobbyists, model drone operators.
So I develop realiable 1m accuracy GPS solution for drones to prevent Drone Fly-away Syndrome.
You are free to join Peer to Drone Crash Investigators to study drone fly-away cases,
drone crash cases ( 100+ cases on a monthly basis).
@Darius
Indeed my problem is on a claim of fast moving RTK solution fixed with a baseline > 1000Km and high accuracy at the same time. I've never seen that in the wild and the papers shown are examples to illustrate my own field experience with any kind of receiver. The only way yet to get someting half-reliable with long baselines are long observations in static mode and checking several times if the actual solution was fine. That is not fit for dynamic work and much less for RTK.
That being said, the only times I've needed to use such long baselines (100-200Km) are to get new control points on hard to reach areas, (swamps, islands, reefs, creeks) mainly to set a handy new Known point where to put an RTK Base to work in dynamic, and that in a 200,000 hectare field experience.
Simply put, for RTK solutions farther away than 75Km of its base is difficult to have something usable and I won't risk high accuracy VS having a base very far away, as it is not needed as we can alway put a base nearby whenever is required while staying on the practical side of being on the field and not using extra improvement methods or risking to loose the day's work.
Please comment me why you say that the Ground CORS are not fit for personal drones? To understand your point. Our professional drone costumers have tested them, use them and are quite happy with the results, and the same applies for ground base movable receivers.
For clarification, any kind or geodetic location is always 3D and the output Hz are only the shown data for navigation not the internal clock. Internally the position calculation is permanent and any trigger is instantaneous. We have never said that the RTKite is a Geodesy, Surveying or 2D unit but exacltly the opposite, it is a Dynamic 3D and fast clocked receiver.
Satellite L band corrections are also a good source of accuracy but for photogrammetry they cannot reach the precision needed.
Regarding your questions of the ESA, of course we know and are in contact with R&D groups both in research centers and private companies. If you want some introduction, let me know.
The research has shown that GNSS baseline processing is dependent on the baseline length. The longer the baseline length the lower the attainable precision. The horizontal and vertical precision of all the observed stations varies as the baseline length changes. The variation is not only dependent on static conventional base station but also CORS.
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@Bernardo,
the above paper is pure tautology, exactly as the previous one.
To study tropospheric corrections (L1 GPS tropospheric error)
you need to study space weather, study theory of jet streams, study model of Coronary Mass Ejections on the Sun ( model by NOAA, NASA).
If you project proposphery and ionosphery on the Earth surface so its obvious you get higher ionospheric, tropospheric GPS corrections error increasing the length of baseline
(basics of trigonometry).
But marine GNSS technology doesn't match personal drone GPS navigation over the ground problems since personal drones fly fast in 3D space and vessels flot slowly in 2D space.
Grid of CORS reference station on the ground is dense.
If you can deploy anchored buoys equipped with GPS receiver,
you can equip the same buoys with transmitter to serve as mobile CORS stations, providing real-time RTK corrections in the region.
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The buoys were equipped with GPS receivers and thus allowed to determine the instantaneous sea surface height that is needed together with precise orbits for the calibration of the satellite’s r adar altimeter.
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But it should be clearly said,
GPS Rover known from geodesy is mobile/static Rover.
Mobile, since it can be easily transported and static since you geolocate fixed ground point.
GPS Marine Rover is 2D space slow floating Rover
Drone GPS Rover is 3D space fast flying Rover
so none of them match and there is no option to employ geodesy grade - high precision GPS solutions into private drones due to latency, due to slow GPS clock (1Hz, 3Hz, 5Hz .. only).
Marine GNSS technology is highly complicated technology.
If you are aware ESA is interested to be injected with high-tech GNSS R&D technology solutions, please let me know, since I have studied either Space Weather, Jet Streams, L1 GPS Ionospheric error, Coronary Mass Ejections models and real-time data processed, or developed 2D, 3D car navigation systems as an independent developer with Nokia Maemo, NAVTEQ (LBS systems)
and I am interested in research contract with ESA since what I see is a mismatch of GNSS theories, solutions, shifted from fully saturated Geodesy GNSS market to
personal drone market.
The concept of GNSS Ground reference station and Rover, developed for geodesy
is not fit for personal drones.
In geodesy, Rover is static
In personal drone, Rover is 3D fast moving (flying) Rover, slowly clocked, any high accuracy GPS results to be expected.
So Anton is right claiming it doesn't matter if GPS installed in personal drone is L1 or L1/L2.
In either case you get slowly clocked GPS technology and accuracy error is function of drone's speed in 3D space.
@Anton, static would be perfect.
A piece of advice, if you surpass these guys below, I recommend you to publish the paper and get a job at the ESA.
Look: https://www.researchgate.net/publication/255625971_TROPOSPHERIC_COR...
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