Jetson-based SDR system features updated AirStack software

Jetson-based SDR system features updated AirStack software

Oct 6, 2021 — by Eric Brown

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Deepwave Digital’s v0.5.0 release of its Ubuntu-based AirStack SDR stack adds CV sample rates and improved recovery support. AirStack runs on Deepwave’s AIR-T and rugged new AIR-T Edge systems based on a Jetson TX2i, Artix-7 FPGA, and an AD transceiver.

Philadelphia-based Deepwave Digital has released v.0.5.0 of its Ubuntu-based AirStack distribution for software defined radio (SDR) applications. The software runs on its AIR-T development boards and enclosed AIR-T Embedded systems. The 0.5.0 release is required for the recently announced AIR-T Edge Series. The initial AIR-T Edge AIR8201 model is on pre-sale at an undisclosed price.

AirStack 0.5.0 architecture
(click image to enlarge)

Like the AIR-T, the AIR-T Edge AIR8201 runs on Nvidia’s Jetson TX2i module along with Xilinx’s Artix-7 FPGA and Analog Devices’ 9371 RF transceiver. The new model adds ruggedization features including pending IP56 protection. Other enhancements include improved frequency range, M.2 storage, and optional GPSDO (see farther below).

The AirStack software and AIR-T (Artificial Intelligence Radio – Transceiver) boards differ from most SDR solutions by adding deep learning enabled by APIs that exploit the AI capabilities of the GPU on Nvidia’s Jetson modules. All the AIR-T systems including the Edge use zero copy memory access “to overcome the data transfer overhead typically associated with GPU processing,” says Deepwave.

AIR-T Edge AIR8201 (left) and AirPack workflow
(click images to enlarge)

The Jetson GPU allows AirStack to run parallelizable applications such as AI and signal processing directly on the RF sensor. “This reduces cost and complexity by eliminating the auxiliary computer that is required by the majority of SDR vendors, and allows for processing to be co-located with the deployed radio without the need to stream data to a remote processor,” says Deepwave. AirStack is available with an AirPack add-on package aimed at easing TensorFlow training for RF on the AIR-T.

AirStack 0.5.0 provides “significant” performance enhancements and API upgrades compared to earlier updates, says Deepwave. In 2019 we reported on AirStack v0.2, which added variable sample rate, phase locking for MIMO, and easier updates, among other features.

AirStack 0.5.0 adds support for Continuously Variable (CV) sample rates, enabled by upgraded firmware interpolation and decimation filters. The filters are continuously tunable between 3.9 and 125 MSPS. The feature only works on the new AIR-T Edge or the AIR7201 version of the AIR-T with a more powerful Artix-7, which was released since the AIR7101 model we covered in 2019 (see farther below).

AirStack now supports multiple firmware images for the Artix-7 FPGA installed along with the AirStack firmware to protect against irrecoverable board states during image loading. There is also enhanced support for the open source Conda package and environment management system. Conda, which has now been upgraded here to Anaconda 4.10.3, adds support for GNU Radio, a core component of AirStack.

AirStack 0.5.0 upgrades to Ubuntu 18.04 with Linux 4.9, as well as Nvidia JetPack 4.6 (L4T 32.6.1) and CUDA 10.2. Other updates include TensorRT 8.01, cuDNN 8.2.1, and SoapySDR 0.8.

AIR-T Edge

Deepwave Digital’s new AIR-T Edge series starts with an AIR8201 model, which like the newer AIR7201 version of the AIR-T Embedded systems, advances to an Artix 7 200T FPGA. The Artix 7 200T provides 215.3K logic cells (LUTs), 740 DSP slices, and 12.14 kbits RAM. (The Artix 7 75T on the original AIR7101 AIR-T system is limited to 75.5k LUTs, 180 slices, and 3.75 Kbits.).

AIR-T Edge AIR8201 with (left) and without cover
(click image to enlarge)

Like the AIR-T systems, the AIR-T Edge Series is available in development board only or enclosed models, and for the first time the latter can safely be placed outdoors. Like the other AIR-T systems, the new model allows for SDR applications to process bandwidths greater than 200 MHz in real-time, claims Deepwave.

The AIR-T Edge AIR8201 offers the same Jetson TX2i module, the ruggedized, 10-year life-cycle variant of the hexa-core TX2, which falls in between the Jetson Nano and Jetson Xavier NX in performance. It also similarly provides an Analog Devices 9371 RF transceiver with 2×2 MIMO. The transceiver provides 100MHz dual-channel transmit and receive. (The second receiver channel requires an optional daughtercard.)

AIR-T Edge AIR8201 mainboard (left) and AIR-T Embedded AIR7201
(click images to enlarge)

Compared to the AIR7201, the AIR8201 adds internal GPSDO (GPS discipline oscillator) module integration. The new model also offers improved receiver performance, including an expanded frequency range of 30MHz to 6GHz (vs. 300MHz to 6GHz). There is also an additional 28 dB of receive gain for 36 dB plus a 2.2 dB noise figure.

Compared to the enclosed versions of the AIR-T systems, the AIR-T Edge AIR8201 provides more extensive ruggedization features. These include a -40 to 85°C operating range (compared to 0 to 70°C) with 95% relative humidity tolerance at -10 to 65°C (non-condensing). The enclosures also adds 5Grms vibration and 140G shock resistance. The enclosure is expected to be certified for IP56 protection.

The major new interface addition on the AIR8201 is an M.2 slot for SATA storage. It is unclear if this replaces the earlier SATA interface. There is now a microSD slot in place of the SD slot

Like the earlier models, the AIR-T Edge is further equipped with GbE, USB 3.0, USB OTG, and 4K-ready HDMI ports. The system runs at a maximum of 25W. Full specs are not yet posted in the AIR-T wiki, but the image shows a serial port and expansion connector, which is presumably used for the previously available DIO.

Also likely on board are the previous WiFi/BT radio, external LO input, PPS, 10MHz reference input, and 8-15VDC input. The PCB appears to retain the earlier Mini-ITX form factor.

Further information

AirStack 0.5.0 is available now for download to Deepwave Digital’s customers. The AIR-T Edge AIR8201 is available for pre-sale at an undisclosed price. (The original AIR-T board without enclosure was available for $4,995 on Crowd Supply.)

More information may be found in Deepwave’s AirStack 0.5.0 announcement, as well as its AIR-T Edge announcement and AIR-T Edge product page.