Introduction

The demand for increasingly powerful hardware continues to grow. To maintain its place as a world-leader in the design of software-defined radio (SDR) platforms, Nutaq added PCI Express (PCIe) support (starting in Release 6.4 of the ADP Software Suite). PCIe reduces the latency and increases the throughput for data transfers between the CPU and FPGA in mixed architecture platforms. The PicoSDR, for example, is equipped with two 4x PCIe point-to-point links.

Application benefits

The benefits of using PCIe in your applications are clear. Let’s take a look at Nutaq’s PicoSDR. The PicoSDR is an SDR solution that has been packaged in a small table-top metal enclosure. It is based on Nutaq’s Perseus AMC carrier and Radio420 FMC daughter cards. The enclosure includes provides access to a PCIe connector that makes it possible to stream an impressive 750 MBPS to an attached PC (approximately 187.5 MHz of IQ bandwidth). Without the PCIe option you are limited to 120 MBPS when streaming with the Gigabit Ethernet interface (approximately 30 MHz of IQ bandwidth).

Now, consider the case with the PicoSDR when you have two transceivers, each with a 28 MHz of bandwidth. The 30 MHz of IQ bandwidth provided by the Gigabit Ethernet can become a real bottleneck, as you only have the PC bandwidth to stream one of them. With PCIe, you can stream to both.

Hardware abstraction

An area where Nutaq really shines is in its support for model-based development and its inherent hardware abstraction. Just like with Gigabit Ethernet, the configuration and control of the PCIe link is fully integrated in the System Generator and GNU Radio supported development environments.

You don’t have to know much about PCIe technology in order to use and benefit from it. Nutaq’s PC drivers and FPGA cores provide the necessary abstraction. All you have to do is select PCI in your designs. To make things easier, Nutaq includes sample applications for System Generator and GNU Radio that demonstrate using the PicoSDR’s PCIe interface to stream media.

System Generator

In your FPGA design, simply select the PCIe option from the Nutaq RTDEx drop-down menu:

GNU Radio

Select the PCIe option from the Nutaq RTDEx drop down menu:

Conclusion

Adding PCIe support will give your SDR platform longevity, enabling it to be used in future projects that have increased bandwidth requirements. This is especially important when you take into account how easily applications developed with Nutaq’s model-based design tools and open source environments can be modified and updated to meet tomorrow’s needs.