NUT2NT+ is an open source, multi-frequency, multi-signal, front-end GNSS receiver board built around the NT1065 chip. It’s a low-power, low-cost, all-GNSS RF-to-bits receiver for satellite navigation enthusiasts.
NUT2NT+ hardware is open source, as is the software - giving the user the ability to set a receiver’s modes and frequencies, to capture all signals continuously, and to have complete control over primary processing features.
Several startups and large companies offer proprietary GNSS positioning solutions and even mobile GNSS software-defined receivers. But a closed ecosystem reduces accessibility for an enthusiast or professional developer, and it limits what a user can do with their hardware. We are happy to bring NUT2NT+ to the world as an open source option.
NUT2NT+ is designed to maximize use-case flexibility.
The flexibility of the NUT2NT+ allows for almost limitless uses - for example:
A NUT2NT+ with an RA125 antenna can be used as a precision positioning GNSS receiver for autonomous cars. Today, autonomous vehicles are equipped with strong processing platforms, like NVIDIA Drive PX2. With NUT2NT+’s processing power, all MIPS hungry GNSS receiver tasks can be done in software. We have already tested NUT2NT+ board with NVIDIA Jetson TX2 board, the younger sibling of the Drive PX2.
A NUT2NT+ with an RA125 antenna can be connected to a small-size, low-cost single-board computer like ROCK64. With such a powerful and small Linux host, all GNSS signal samples can be captured continuously without any loss for offline downloading and processing outside the logger. It could be used in accident reconstruction or GNSS reflectometry.
Software source code is available on GitHub. The software includes:
We have three enclosure options for the board:
No enclosure: you can use the board as-is or make your own enclosure. The PCB sources will be provided, as well as drawings and step 3D-models needed to design your own enclosure.
Low-cost enclosure: the EXT-9162 enclosure from Bud Industries will come with custom front and back panels. Drawings of the panels will be also provided on the Amungo GitHub. This option will help protect your board. This enclosure is also lightweight - about 40 gramms.
Shielded enclosure: a custom-milled aluminium enclosure with good RF shielding, weight about 100 gramms. The 3D-models for this enclosure will also published.
All boards will be equipped with a tested USB3 type-C cable.
All RF cables will be handmade from RG-316 coaxial cable.
NUT2NT+ RF Cable
Our RA1 and RA125 antennas are both based on a four-feed patch antenna structure providing best Phase Center Variation (PCV) performance in patch antenna class. Please read this paper for details on the importance of proper antenna uniformity.
We also have three enclosure options for the antennas:
No enclosure: you can use the board as-is or make your own enclosure. The 3D-models needed to design your own enclosure will be published.
Aluminum enclosure: a milled aluminium enclosure with good RF shielding and TNC connectors on-board. These enclosures are ready to mount on standard 5/8" screw mast. The hat cover is made of UV-resistant plastic.
Magnetic enclosure: also a milled aluminium enclosure. Like the aluminum enclosure, but capable of magnetically mounting on the roof of a vehicle.
More then a year has passed since our first campaign offering the NUT4NT board. During this year, we supplied NUT4NT boards and antennas to customers around the world. Based on user feedback from this board, we designed the NUT2NT+ to be lower-cost, have lower power consumption, have enclosure options, and have more on-board features.
There are no other open boards in the world dedicated to GNSS SDR. So we compared the NUT2NT+ with our legacy NUT4NT board.
|Number of RF inputs||2||4|
|Number of receiving channels||4||4|
|FPGA inside||Lattice ECP5||No|
|RF inputs dedicated to GNSS band||Yes||No, wideband|
|Internal TCXO control||Yes||No|
|External oscillator input/output||Yes||Yes|
|Low cost enclosure option||Yes||No|
|Onboard RF filtering||Yes||No|
|Power from USB||Yes||No|
|Antenna power injector circuit||Yes (software-controllable)||No|
We have tested the first NUT2NT+ by recording samples and processing them with well-known GPS receiver Matlab code. The SNR figure shows the system noise floor declared.
For the last year, we’ve worked through a series of software bugs and fixes, and today it is quite stable. We plan to create additional integrations with open source GNSS-SDR software projects.
All NUT2NT+ hardware sources will be opened after campaign reaches the goal.
As soon as the funding goal is reached, we’ll purchase the PCBs and components needed for the early boards, as well as for the antennas and cables. Then we’ll project the demand for the antenna resonators and purchase substrates with double gap. We’ll start assembling NUT2NT+ units after the campaign ends. After the campaign concludes, we’ll also purchase all the metal parts, PCBs, and components needed for the remaining orders. Here we’ll also review the demand for antenna resonators and purchase the rest. Then we’ll test all assembled boards (with cables and antennas) on a table and with good sky conditions. After that, boards should be ready to ship.
We have tried and true manufacturing and supply partners in Estonia and around the world.
All orders will be shipped using Crowd Supply’s fulfillment services, from the United States. Please read this useful page about ordering, paying, and shipping from Crowd Supply.
We already have good sources for electronic components, PCBs, and metal parts. We will assemble the boards with our own equipment for full control of the build quality. But, as with any hardware project and any amount of preparation, there can still be unexpected supply shortages or manufacturing issues. We have a lot of experience at finding problems in hardware and we have added a few weeks of padding into the schedule.
One especially difficult task is antenna resonator manufacturing. Delivery time of substrates is long, as is the manufacturing of the resonators themselves. This is why we have already manufactured 100 of the L1 resonators and 20 of the L2/L5 resonators. But we will keep an eye on sales numbers during the campaign and order the resonators in advance if necessary.
Should any issues arise during the manufacturing process, we’ll keep backers apprised via project updates.
Campaign video music: Scott Holmes - CC BY 4.0
Thanks to Crowd Supply for providing copyediting, other help, and patience
Strategic management, design of antennas
Hardware design, manufacturing and testing
Software development, embedded and signal processing
RF circuits design, RA antennas LNA and NUT2NT+ board's RF circuits
Software engineering, C/C++ Developer, NUT2NT+ GNSS-SDR support
Supply and fulfillment management
FPGA Design and Verification Engineer, FAE
FPGA code design
Metal parts design