by Fairwaves

The first ever truly embedded SDR

View all updates Feb 11, 2017

MIMO and Independent Receive/transmit

We often get asked how many receive and transmit chains does XTRX have and whether you can tune them to different frequencies, so I decided to clarify this once and for all.

XTRX is a 2×2 MIMO transceiver, which means that:

  1. XTRX has 2 receive channels and 2 transmit channels, so you can see “Rx1”, “Rx2”, “Tx1” and “Tx2” antenna connectors on the board.
  2. Both receive channels share a common local oscillator (LO) and thus always receive the same frequency. Same for transmit – both channels share a common LO and always transmit at the same frequency.
  3. At the same time receive and transmit have independent LOs, so you can transmit on one frequency while receiving on another – a mode commonly referred as Frequency Division Duplex (FDD). For communication systems where transmitter should work on the same frequency as a receiver (also known as Time Division Duplex, TDD) LO can be shared between transmit and receive sides of XTRX.

If you want to receive or transmit at two frequencies located close to each other, you still can do this with XTRX by digitally shifting one of the channel frequencies relative to the central frequency. This is called baseband shifting or mixing and can be done either at the time you generate your signal or later by XTRX itself. How far you can move your transmit/receive frequency from the central frequency is limited by the configured sample rate. E.g. for a sampling frequency of 100 MHz you can shift your transmit/receive frequency by 50 MHz above or below the central frequency.

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Product Choices


XTRX Pro Rev 5

XTRX Pro Rev 5 board. Does not include any cables, antennas, or adapter boards.


PCIe x2 Lite Adapter

This PCIe card securely holds an XTRX board (not included) so it can be used in a standard PCIe x4 slot. This adapter achieves the full 10 Gbit/s raw bus bandwidth and can be plugged into x4/x8/x16 PCIe slots. A six-pin JTAG connector makes it easy to program and debug the FPGA. Includes six SMA-to-U.FL cables, two screws for mounting your an XTRX board, and four 8 cm U.FL-to-U.FL cables.


4G/LTE External Antenna

From the Crowd Supply Basics project.

Abracon External Antennas exhibit low return loss characteristics, high gain, and Low Voltage Standing Ratio (VSWR). These external antennas are linearly polarized and come in a low profile package.


U.FL-to-SMA Cable

From the Crowd Supply Basics project.

A Hirose U.FL to SMA (jack) bulkhead straight connector with a 1.32 mm diameter cable. Less than -2 dB cable insertion loss up to 6 GHz. Both connectors are gold-plated brass and the cable conductor is silver-coated copper.


Active GPS Antenna

From the Crowd Supply Basics project.

A low-noise active GPS antenna suited for the GPS L1 band. Accepts 3-5V DC and outputs RF via an SMA(m) connector. Optional adhesive mounting.



We are a vertically integrated vendor of cellular equipment focused on the needs of emerging markets. We are developing, manufacturing, deploying, and operating turn-key cellular network solutions including radio equipment, towers, power and backhaul all the way to a core network and SS7 interconnect. Our team has been building software-defined radios and systems based on them since 2009 and is well known for its ClockTamer, UmTRX, and UmSITE products.

Alexander Chemeris


Sergey Kostanbaev

Software & Firmware Development

Andrey Sviyazov

Hardware Design

Albert Gardiner


Andrey Bakhmat


Andy Avtushenko


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