Frequently Asked Questions
Short answer: Yes!
Some GPS receivers are subject to International Traffic in Arms Regulations (ITAR) if they are to be exported from the United States. The types of GPS receivers that are covered under these regulations are defined in the US Munitions List, Category XI part (c):
None of these categories apply to us, Piksi wasn't designed for military use or to control massive UAVs that can deliver half-tonne payloads. It was designed for small civilian and hobbyist UAVs. The only category that could apply is (c) (2):
"GPS receiving equipment with any of the following characteristics: (2) Designed for producing navigation results above 60,000 feet altitude and at 1,000 knots velocity or greater"
In the Piksi software we implement these restriction and prevent the receiver from outputting navigation solutions if the velocity is greater than 1,000 kts and the altitude is greater than 60,000 ft. Notice this is an "and" condition, you have to be going too fast AND too high. Use on a high altitude balloon for example would be ok, as you are high but slow.
We have had enquiries about people modifying the software (as it is open source) to remove these restrictions. We do not support such modifications and will not be merging any such changes into our codebase. If you were to make such changes there may be legal implications for doing so and we suggest you find a good laywer!
We are interested in working with people inside the United States on cubesat and amateur rocketry projects and seeing what is possible legally but we will not be shipping anything modified for these uses outside the US.
Note, there are possible uses in rocketry without violating these limitations - the critical phases of flight, launch and apogee, are usually only violating one but not both conditions. It is also possible to capture data to be post-processed into navigation solutions after the fact.Last updated:
Yes! We can already output RTCMv3 messages and intend to support RTCMv3 input as well. This allows you to use the Piksi as a roving receiver with an existing base station, Continuously Operating Reference Station (CORS) or Network RTK solution.
We think it is important to support industry standard protocols to allow interoperability with other vendors and existing infrastructure.
Unfortunately we do not directly support NTrip as this is a network protocol and Piksi does not have a direct network connection. However you can use Piksi with standard (free) NTrip client software running on a computer that outputs RTCM messages over serial.Last updated:
Unfortunately it is not possible to do RTK positioning indoors.
Not only are GPS signals are extremely weak indoors, but you can no longer assume they have travelled in a straight line to the receiver. The signal will usually have reflected several times off of walls and surfaces before it makes it to an indoor receiver, destroying the ability to do accurate positioning.Last updated:
We are just starting to work with developers on integrating Piksi with different autopilot systems. We hope that by the time Piksi is ready to ship it will already be supported by several autopilots.
In particular 1 BIT SQUARED have offered to develop support for the Paparazzi autopilots and 3D Robotics are going to be helping add support for APM/ArduPilot based systems.
If you are a developer please get in touch and let us know what we can do to help with integration into your system.Last updated:
We haven't yet selected which model of radio to include and we will ask for some feedback from our backers before making any decisions.
However, we included the radios in the RTK kit primarily to give you something plug-and-play so you can get they system working out of the box. They won't be the fanciest radios in the world and it is not meant to be a one size fits all solution.
There are hundreds of different radio modems available all with different ranges, power consumptions, sizes and costs. Once you have got up and running with the Piksi with the included radios you may well want to replace them with something else particularly suited to your application. Luckily its very easy to use the Piksi with just about any radio modem that supports simple serial communications.Last updated:
Maybe. We have had a lot of interest in this option. We will send a survey out to our backers asking them for their feedback on radio choices after the campaign has finished.Last updated:
Yes. Fundamentally you just need to get some serial data from the reference station Piksi to the one on the vehicle. You can pass the data over an existing link if you'd like.
Specifically for MAVLink, 3D Robotics are teaming up with us to make sure this is supported as soon as possible.Last updated:
The 4 centimeter expected precision we talk about in the video and project description is the expected horizontal precision of the receiver - this is the standard metric quoted for GPS receiver precision. Horizontal precision is typically 2-3 times better than vertical precision for GPS receivers, and so we expect the vertical precision to be around 8-12 centimeters.Last updated:
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