Tagged: XTRX

Updates to the HF Performance of the XTRX SDR

Late last month we posted about the Fairwaves XTRX SDR which is a Mini PCIE TX/RX capable SDR with 10 MHz - 3.7 GHz tuning range and 120 MSPS sample rate that costs $199 US and is currently crowdfunding on CrowdSupply. At the time of this post the XTRX is currently 84% funded.

Recently the XTRX team released an update regarding the HF performance below 30 MHz. The update shows that signal attenuation starts to significantly reduce in the HF bands with the 3dB point being at 11 MHz. At 6 MHz the attenuation is at 13 dB, and at 2 MHz it's up to 29 dB. This attenuation may not be too bad though especially for strong HF signals, or perhaps a preamp like the LNA4HF could be used. They attempted to review their design to reduce the attenuation, but found that there is no easy fix especially with having such restricted space as in a PCIE card.

They also note that HF reception with the LMS7002 chip used on the XTRX can be problematic as the LO is fixed to a minimum of 30 MHz. So to receive below 30 MHz the receiving bandwidth needs to be increased which can cause saturation from any strong out of band signals. However, they tested with some very simple external bandpass filters for the 49m band (5.8 - 6.2 MHz) and had decent results.

The XTRX team also added a new breakout header to the board which provides direct connections to the LMS7002 chip ADCs for direct sampling. This could provide even better HF performance with an appropriate custom frontend.

XTRX HF Attenuation Graph
XTRX HF Attenuation Graph

XTRX SDR Campaign Now Live: Mini PCIE Based TX/RX SDR for $199

Back in early November we posted about the upcoming XTRX SDR, which is a small form factor 2 x 2 MIMO TX and RX capable SDR that is designed to fit into laptop Mini PCIE card slots. It is based on the LimeSDR RF chips, and has a tuning range of 10 MHz - 3.7 GHz, with a sample rate of up to 120 MSPS. It is also has some interesting additional features such as a built in GPSDO and an onboard FPGA which can be used to accelerate DSP tasks as well. The Mini PCIE interface was chosen for it's low latency transfer rates.

The card is designed for use cases such as creating LTE cellular networks, creating software defined 2G/3G/4G modems and using on board drones and in embedded systems. It can also be used for standard wideband monitoring and of course any other SDR applications compatible with Lime chips.

Today the crowdfunding campaign for the XTRX has begun. The early bird pricing is $179 USD (with 71 left at the time of this post - going down fast!), and the regular price is $199 USD. There are accessories available as well such as antenna and cable kits, a PCIe x2 adapter and a USB 3.0 adapter kit with enclosure. The XTRX team are hoping to raise 90k USD, with already 8k USD having been raised at the time of this post.

The XTRX Board
The XTRX Board

XTRX: Soon to be crowdfunding Mini PCIe based TX/RX SDR

Over on the crowd funding site crowdsupply.com there have recently been several updates on the Fairwaves XTRX SDR. The XTRX is an upcoming TX/RX capable SDR in a tiny Mini PCIe form factor. Mini PCIe is the expansion slot system used on some laptops. The SDR itself will be 2 x 2 MIMO, with a tuning range of 10 MHz - 3.7 GHz (down to 100 kHz with some degradation), and have a sample rate of up to 120 MSPS. It uses the LimeSDR RF chipset which provides most of the hardware required.

The XTRX is not yet for sale, and is planned for a crowdfunding run on Crowdsupply 'soon'. You can subscribe to future updates on their page. No word yet on pricing, but according to one of the developers comments on Reddit the price will be somewhere between the LimeSDR ($299 USD) and LimeSDR Mini ($139 USD). Eventually in the future if they can tap into a mass market they hope to get the price down to $50 USD.

Features & Specifications

  • RF Chipset: Lime Microsystems LMS7002M FPRF
  • FPGA Chipset: Xilinx Artix 7 35T
  • Channels: 2 × 2 MIMO
  • Tuning Range: 30 MHz - 3.8 GHz
  • Rx/Tx Range:
    • 10 MHz - 3.7 GHz
    • 100 kHz - 3.8 GHz with signal level degradation
  • PCIe Bandwidth:
    • PCIe x2 Gen 2.0: 8 Gbit/s
    • PCIe x1 Gen 2.0: 4 Gbit/s
    • PCIe x1 Gen 1.0: 2 Gbit/s
  • Sample Rate: ~0.2 MSPS to 120 MSPS
  • Reference clock:
    • Frequency: 26 MHz
    • Stability: <10 ppb stability after GPS/GNSS lock, 500 ppb at start up
  • Form Factor: full-size miniPCIe (30 × 51 mm)
  • Bus Latency: <10 µs, stable over time
  • Synchronization: synchronize multiple XTRX boards for massive MIMO
  • GPIO: 4 lines @ miniPCIe connector, 3 lines @ FPC edge connector
  • Accessories: miniPCIe-USB3 converter, miniPCIe-PCIe converter, etc
XTRX Prototype
XTRX Prototype