Dear Community,

Drotek, French tech start-up is proud to release its L1 RTK GNSS ! RTK technology allows to enhance GNSS positioning and to go down to centimeter level precision.

We have seen a lot of RTK boards coming up. However we have witnessed no good integration for the UAV segment and no performance enhancement in difficult environments.

This is why we decided to develop a solution to cope with these issues. Drotek is specialized in electronic design for UAVs and has put all its expertise in designing this board, jointly with French National Center for Space Studies (CNES) and French Institute for Aeronautics and Space (ISAE).

What is RTK for?

RTK technology uses corrections from a second GNSS receiver (called “base”, the other mobile receiver is called “rover”) in order to correct errors that lead to meter level precision. It has been used for a long time by surveyors, but at a very high cost. Today we want to trivialize this technology.

Our two years spent on developing this product have led us to focus on several points, such as connectivity, signal quality, EMI, real-time, etc...



We have compared our system’s performance with dual frequency receivers (in blue, Rover : Septentrio AsteRx 3 L1/L2 + Novatel geodesic antenna in RTK with base Trimble NetR9 + TRM59800), and it is pretty astonishing!


RTK works well in clean open-sky environments, but we like to test our device in difficult scenarios. Urban canyon is stil a pipe dream, but some route on ground robot in medium-hard environment (buildings, trees…) gives pretty good results :


Comparison between single GPS (red) and RTK : have a look at the left side under the tree. Single position gets highly contaminated by multipath, whereas the big ground plane and the Tallysman antennas filter it quite well :


Comparison between RTK Drotek (orange) and another open-source RTK solution (yellow) :


Base correction data can be sent through serial port with 3DR Radio types but also through cabled or wireless Internet for those want to get rid of range limitations. All drivers and server programs are already in the board. The following table sums up the different possible ways of communication between rover and base.


We are currently developing LoRa based transmitters, hoping that these will fulfill our expectations (we are quite excited about them!). Coming soon.

We truly believe in open-source community, but this board has also been designed to work “as is”. All boards will be delivered flashed and ready-to-use, with really little configuration, mainly for non-advanced users who would wish to get to precision without spending too much time on understanding how it works. Our wiki will explain everything step-by-step, but will also provide support on using RTKLIB graphical tools for post-processing and analyzing data. Do not forget to check our Github, we will publish in it really soon!

All our boards are stamped “Made in France”, we pay a lot of attention to the devices we manufacture in our French factory. Our motto is open source and open hardware, we work this way and we will stay this way. We want sell the atoms not the bits.

The package will be available in our site for pre-ordering. The expected release date is in one month, with a price of 699 € excluding VAT.

Our website is currently being redesigned, hope you will appreciate the new one! There will be plenty of content on how to use all the devices we manufacture, from little sensors to big boards!

Some additional exciting results :

This picture depicts the precision you can expect with good conditions, amazing!



A little demonstration (shot yesterday!) :

We modified an Iris+ drone, removed its GPS and replaced it by our board. Take-off is manual, and as soon as the drone lifted we triggered Return To Launch mode. The drone succeeded in landing on the table approximately 1 out of 2 times. It touched the table with at least two feet each time we tried the procedure.  Wind conditions were quite gentle but with a fair amount of gusts. Even if the board provides precision, there has been a lot of work on the controller’s PIDs to achieve this result!

We used a Netgear WiFi router to transmit raw data from the base to the rover, using Edison's WiFi. Base was connected in Ethernet to the router, everything powered by a 4S LiPo and a 12V power module.


We will offer a board to the person who comes up with the coolest name for the device !

10% off on pre-order !


See you soon in our website !



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  • @Dan, ideal solution may be a L1/L2 receiver as base (quicker fix time, ready for PPP), and L1 only as rover. L1/L2 as rover also may be justified for long range vehicules. But I think 95% of mapping application is within a couple of km from base, so  L1 rover probably the best economic choice.

  • @Guy, of course we can consider this antenna, I think we will order a couple of them so we can test them. It is a custom version of TW2410, so it has no magnetic band and shorter cable. Otherwise TW4421 might be a compromise between performance/weight.

  • @Darius - RTKLIB is just an open source implementation of RTK algorithms that have been used by proprietary systems for some time.

    Great module drotek, it looks very nice indeed!

    One of the inherent draw backs of single frequency RTK is the time to resolve the integer ambiguity and susceptibility to loss of lock. The situation gets even worse with smaller patch antennas, dynamic vehicles, high EMI etc. Without having an indepth understanding of RTK, I suspect that dual frequency systems do better since they have more information. The downside to dual frequency is the expensive electronics, however, the Tersus product seems to have made a price breakthrough (although still $2k).

    The results that have been provided are a good start, however it would be even better if there were some results aboard a small multirotor that is performing fairly dynamic maneuvers, since that is a large application area in this forum.

  • @Thorsten, a good passive antenna like Taoglas with an adapted ground plane can give good results. SNR levels can be as high as 50 in open sky very clear environments. However, if you move to more "populated" environments performance substantially worsens because of multipath effect. Tallysman antennas are dual feed, so they filter all the non circularly polarized electromagnetic waves far better than the patch does. An example :


    The red path is a trajectory calculated with RTK in post-processing. Base and rover were two M8Ts with Taoglas patch : http://www.drotek.com/shop/fr/home/679-module-gps-ublox-neo-m8t-mag... with rover mounted on a bike. As you can see, the trajectory is really good in open sky, but gets highly contaminated as soon as trees degrade the signal. This phenomenon is highly attenuated by Tallysman antennas, as you can see on the pictures of the initial post.

  • @Guy,

    Fig. 9, 10, 18, 19


  • VRS would be a great solution here also. SwiftNav is sure to have that nut cracked soon.

  • T3

    Hi all at Drotek,

    back to the topic...

    Can you say something about the difference in accuracy comparing the Tallysman antennas vs "normal" Taoglas patch antennas?

    Well, I assume you have a reason to select the Tallysman ones. I am asking because your RTK version is about 100g heavier compared to common XXL modules. So it is flight time (and price) vs. accuracy.

    Best regards,


  • @Kevin,




  • @Kevin,

    just read

    I you need latest EU pending legislation on drones from Brussels,
    just let me know

    Commercial use of drones in Europe would be divided into three categories starting with a minimally restrictive “open” category, according to a new regulatory approach the European Aviation Safety Agency (EASA) released this week. Plans call for presenting the European Commission with “concrete” regulatory proposals for the open category by December.

    The proposed regulatory framework, or “concept of operations” that EASA released on March 12 envisions the open as well as “specific” and “certified” categories with ascending levels of requirements based on the associated risk and required competence of an operation. The framework “is not simply transposing the system put in place for manned aviation but creating one that is proportionate, progressive (and) risk based,” the agency states.

    Upon acceptance, the framework would “render obsolete” the current regulatory regime in Europe, which assigns EASA responsibility for regulating drones having a maximum takeoff mass of 150 kilograms (330 pounds) or more, with civil aviation authorities in individual countries responsible for aircraft weighing less. EASA, based in Cologne, Germany, is the European Union’s aviation safety authority.

    EASA’s release of the concept of operations followed a high-level conference in Riga, Latvia, on March 5-6 that produced consensus among EU member states on five principles for introducing drones in European airspace beginning in 2016. Among those principles, the conference delegates agreed that drones should be “treated as new types of aircraft with proportional rules based on risk,” and that EASA should produce a basic regulatory framework “without delay” to help the private sector make investment decisions and begin providing services.

    “Rules should be simple and performance based, to allow a small start-up company or individuals to start low-risk, low-altitude operations under minimal rules…similar to the modern product safety regulations applied in other sectors,” states the Riga Declaration on Remotely Piloted Aircraft (drones). “Higher risk operations would be gradually subject to more stringent regulations or operational limitations.”

    According to EASA, the “low energy,” or small drones allowed to operate in the open category would be restricted to flying within the operator’s visual line of sight, to no higher than 150 meters (492 feet) above ground or water, and outside of specified reserved areas, such as for airports. Flights above crowds would be prohibited, but flights above people not involved in the operation allowed. The operator would not need a pilot’s license or an authorization from an aviation authority; rather open-category operations “can be overseen through the police, as for cars for instance.”

    The specific category would require the operator to perform a safety risk assessment of the planned mission, identifying mitigation measures that a national aviation authority would review and approve through an operations authorization (OA). “The OA should clearly specify the specific conditions and limitations for the intended operation and can be issued to authorize a single event or a series of operations under specified conditions,” EASA states. “The operation close to crowds could be acceptable when the vehicle has some additional functionality (e.g. automatic loss of link procedures, impact energy limiting devices).”

    The certified category envisions drones that would fly with manned aircraft in unrestricted airspace. “These operations and the aircraft involved therein would be treated in the classic aviation manner,” the agency states. “Integration in non-restricted airspace would be subject to a safety assessment of the ATS (air traffic services) provider.”

    Pilots engaged in the certified category would require licenses. The unmanned aircraft model would require a type certificate, and the drone being used an individual certificate of airworthiness and a noise certificate. The airworthiness certificate may or may not also cover the aircraft’s ground control station and “the possibility of an independent approval of a control station could be envisaged.”


    Drone registration in Europe, France ..

    The European Commission plans to set “tough new standards” to regulate the operation of UAVs, known as remotely piloted aircraft systems (RPAS) in Europe, before they are more widely introduced into unrestricted airspace in 2016. The standards will cover safety, security, privacy, data protection, insurance and liability, the commission said.

    “Civil drones are increasingly being used in Europe, in countries such as Sweden, France and the UK, in different sectors, but under a fragmented regulatory framework,” the commission said on April 8. “Basic national safety rules apply, but the rules differ across the European Union and a number of key safeguards are not addressed in a coherent way.”

    In a statement accompanying the announcement, Siim Kallas, the commission’s vice president for mobility and transport, said: “[M]any people, including myself, have concerns about the safety, security and privacy issues relating to these devices…If ever there was a right time to do this, and to do this at a European level, it is now.”

    In December 2013, the European Council asked the commission to develop a regulatory framework for safely introducing RPAS into European civil airspace beginning in 2016. The commission plans to conduct an “in-depth impact assessment” this year to examine the associated issues and then propose legislation to the European Parliament. The European Aviation Safety Agency (EASA), the commission’s technical advisor, will develop EU-wide standards based on the principle that RPAS should operate to an equivalent level of safety as manned aircraft. EASA will also develop security requirements “to protect information streams” and propose for RPAS operators, air traffic controllers and others legal obligations that will be enforced by national authorities.

    Independent of the commission’s announcement, Spain’s State Aviation Safety Agency (AESA) issued a policy memo on April 7 stating that it “is not permitted and never has been” to operate RPAS commercially in that country to perform aerial work. The agency said it is collaborating with industry to develop a regulation that will establish a new classification for RPAS, the conditions under which they can operate, and requirements for certification, manufacture, maintenance and operation of civil unmanned aircraft.

    “We must emphasize that drones are aircraft. As such, they are subject to legislation currently in force in Spain [for] general aviation, as well as the rest of regulatory aeronautics,” the AESA memo reads, according to a translation. “There is the mistaken belief, in that layer of airspace that extends from the ground up to 400 feet, you can fly with these devices without restrictions.”

  • @Kevin,

    just read


    Are you really not aware of EU standards, never contacted EU Comission, TUV Bayern, ISO Geneve ?

    If you mean drone registration in Europe, legislation is pending.
    (just read follow-up)


    Trimble GPS mapping solutions receive TÜV certification under EU Agricultural Directive Commission Regulation 796/04
    By Trimble Australia 22 May 2009
    Supplier News
    Contact Trimble Australia
    Trimble Australia  have announced that their GeoXT handheld computer, GPS Pathfinder ProXT receiver, and GPS Pathfinder ProXRT receiver obtained TÜV certification under the European Union (EU) Agricultural Directive Commission Regulation 796/04, Article 30. The directive supports the validation of area measurement methods for agricultural parcels in order to comply with the current common agricultural policy (CAP) of the EU.

    Before January 2005, under the previous CAP, farmers received subsidies according to how much they produced. In June 2003, EU agricultural ministers agreed on fundamental reforms to those subsidies and established new rules under which farmers can claim a direct income support payment that is no longer linked to production. Commission regulation 796/2004 describes the ‘cross-compliance’ rules covering the requirements for all direct payments, including the requirements for accurately measuring the size of parcels under consideration for payments.

    Article 30 of the regulation states that agricultural parcel areas shall be determined by any means proven to assure measurement of quality at least equivalent to that required by applicable technical standard, as drawn up at Community level. A measurement tolerance shall be defined by a buffer of maximum 1.5m applied to the perimeter of the agricultural parcel. The certification was performed for Category A of the regulation, which requires a buffer accuracy of less than 0.40m, far beyond the maximum tolerance of 1.5m, according to the area measurement validation scheme from the European Commission, Joint Research Centre – ISPRA, Institute for the Protection and Security of the Citizen, Agriculture unit.

    TÜV SÜD is an international service organisation that focuses on the consulting, testing, certification and training. Actual TÜV certification was provided by NavCert, a subsidiary of TÜV SÜD, who offer support for the development, testing, and certification of positioning and navigation systems. TÜV certification involves rigorous testing of the applications for which a product is designed.

    TÜV certification includes verification that the strictest European regulations are satisfied and ensures that the specifications are stated correctly. Periodic retesting of the product is required to maintain TÜV approval. Attaining this certification is a mark of quality and assurance that use of Trimble’s products for the mapping of agricultural parcel areas meets EU standards."

    Trimble GPS mapping solutions receive TÜV certification under EU Agricultural Directive Commission…
    Trimble Australia have announced that their GeoXT handheld computer, GPS Pathfinder ProXT receiver, and GPS Pathfinder ProXRT receiver obtained TÜV c…
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