Nutaq's PicoDigitizer-125 Series

"I haven’t seen another device which has such a powerful FPGA, so many high speed ADC channels and also a CPU card integrated in such a small chassis.”

Manuel Cuntz – DLR

DLR is Germany’s national research centre for aeronautics and space. Its extensive research and development work in aeronautics, space, transportation and energy is integrated into national and international cooperative ventures. As Germany’s Space Agency, the German federal government has given DLR responsibility for the forward planning and implementation of the German space programme as well as international representation of Germany’s interests.

What is the application?

We are developing satellite navigation receivers for safety critical applications. Our main focus is on safety of life applications in the domain of civil aviation.

Array processing is a key technology to increase the robustness of the navigation solution. With the GNSS receiver that is implemented on the Nutaq hardware, we are able to apply digital beamforming to suppress multipath effects and to gain a higher SNR to the line of sight signals. A direction of arrival estimation helps us to authenticate GNSS signals.

What are the technical challenges that you needed to address?

In multi-antenna satellite navigation receivers, we need to cope with large signal bandwidths of more than 20 MHz. Beside that we need to handle the signals of multiple antennas and multiple frequency bands. Therefore the high count of ADC channels with a high sampling rate is very important.

The GNSS signals have only approx 0.1 fW receive power at the RX antenna. Therefore it is very easy to jam. To take appropriate countermeasures, a high dynamic range of the ADC is important. The low phase jitter of the clock and the 14 bit resolution of the ADCs is ideally suited for that. The huge Virtex-6 FPGA helps us to reduce the high amount of data of the ADCs, so the CPU can control our loops. 

Why did you select Nutaq's digitizer solutions?

The technical specification of the PicoDigitizer-125 Series is unique. I haven’t seen another device which has such a powerful FPGA, so many high speed ADC channels, and also a CPU card integrated in such a small chassis. For the development of our receivers we need both a huge FPGA for parallel processing and a powerful CPU for floating point calculations. The PCIe interface with very low latency and high data throughput allows us to close our control loops between the FPGA and CPU in real time. 

For scientific research we do not have the time to spend much effort in writing device drivers. Therefore the complete suite of BSDK and BSP is very important. Having a fully working default system with examples to get started, is also a unique selling point.

We had very good experience with Nutaq's previous VHS-ADC digitizer systems. They already had and still have a outstanding performance in high speed ADCs with multiple channels. The channel isolation, clock jitter performance and phase synchronization is outstanding.

Related articles

 Field Test: Jamming the DLR Adaptive Antenna Receiver 

 Lessons Learnt: The Development of a Robust Multi-Antenna GNSS Receiver