xMASS SDR is a modular, high-performance MIMO transceiver optimized for industrial, academic, and advanced software-defined radio (SDR) applications. It features 8 RX and 8 TX channels that can be synchronized. Its modular design enables simple maintenance and facilitates the creation of high-order MIMO systems using well-established building blocks.

Synchronization

xMASS SDR is outfitted with four detachable xSDR boards based on the LMS7002 RFIC. It also includes metal mounting brackets, cabling for all TRX/RX ports as well as the GPS port, and a dedicated board to synchronize the xSDR units. Each individual xSDR board facilitates two transmit channels and two receive channels. By synchronizing multiple xMASS SDR systems, the channel capacity can be effectively doubled, allowing for up to 16 transmit and 16 receive channels simultaneously.

The system can operate at up to approximately 60 MSPS per eight channels in sustained mode or up to approximately 100 MSPS per four channels, which is ideal for 4G and 5G applications.

A Comprehensive MIMO Solution for 4G & 5G

Unlike entry-level MIMO systems, xMASS SDR can transmit signals as well as receiving them. Its functionality extends beyond just direction finding and comprehensive spectrum monitoring. xMASS SDR is well suited for developing sophisticated 4G or 5G solutions using srsRAN, Amarisoft, and other multi-user communication systems. Through beamforming, xMASS SDR enables focused transmission toward a specific location without requiring physical antenna adjustment. As an example of its versatility, you could use the first and second SDR boards for 4G, the third for PMR, and the fourth for spectrum monitoring.

Applications

• 4G/5G network development
• Direction finding
• Beamforming
• Comprehensive spectrum monitoring

Features & Specifications

• 8 channels at 30-3800 MHz RX/TRX
• 60 MSPS per 8 channels or 100 MSPS per 4 channels
• GPS or external 1 PPS sync
• Internal 26 MHz ± 280 ppb or external reference clock
• PCIe x4 form factor (with only 2 PCIe lanes used)
• RFIC: 4x LMS7002
• FPGA: 4x XC7A35T
• Clock sync IC: LMK05318
• Bifurcation modes: Full 8x8 MIMO or 2 independent 4x4 MIMO or 4 independent 2x2 MIMO systems
• PCIe 3.0 x2 connection
• RF connectors: SMA - MHF4

Simplified Block Diagram

Comparisons

xSDR Module

We’ve made two revisions of xSDR, and it’s now a mature and well-tested module. It has the same M.2 breakout as uSDR. While they share the same M.2 2230 key A+E form factor, they have different RFICs: uSDR uses an LMS6002D while xSDR uses an LMS7002M.

xSDR’s M.2 pins 62 and 64 are routed to the LMS7002M’s LNA3 port, which allows for the alignment of the modules without breaking RF RX/TRX paths.

xMASS Synchronization Board

We use TI’s LMK05318 clock synchronization IC to feed a reference clock (optionally 1 PPS or 10 MHz or GPS tamed) to all modules. It has a BAW that provides an ultra-low-jitter clock source as a reference. The xSDR module in slot A is the controller, issuing synchronization commands for the whole array. These commands are distributed across all xSDR boards (and then sent back to the controller), which allows for time synchronization within the clock cycle across all modules. RF is trickier, since the LMS7002M doesn’t have built-in capabilities for local oscillation (LO) or digital decimation or interpolation filter synchronization. There are a couple different methods that could be used for calibration and tweaking. We use external sources for all modules on RX, estimate phase difference, and apply correction in the baseband. Once RX is synchronized, we use RX-TX loopback to calibrate TX. We are continuing to work on improving calibration.

Support & Documentation

xMASS and xSDR share the same host code base as our standard uSDR board, which was released under the MIT license, and our universal support libraries are hosted on GitHub, which allows for an easy transition from uSDR to xMASS with minimal software modification requirements. FPGA gateware is released under the CERN-OHL-P-2.0 license and can also be found on GitHub.

Our pre-built packages are hosted on Launchpad, and our documentation can be found here.

Our goal is to make sure that all well-known software out there is being tested on the device. xMASS currently supports the following software:

• SRSRAN
• SoapySDR
• GNU Radio
• Amarisoft
• Lime Suite

We are also working on LimeSuiteNG support for xMASS.

Manufacturing Plan

We are proud to be manufacturing xMASS here in the United States, and we already have everything we need to deliver the first ten units quickly. We have streamlined our manufacturing process, as well, so we don’t expect any issues producing additional units either. We’ll keep you updated about our manufacturing schedule through regular campaign updates.

Fulfillment & Logistics

Mouser Electronics, will be handling distribution to backers worldwide. You can learn more about Crowd Supply’s fulfillment service under Ordering, Paying, and Shipping in their guide.

Risks & Challenges

We have significant experience with electronics production and have made plans to mitigate the usual risks. We are working closely with suppliers to ensure that we will be able to source the parts we need and have already stocked sufficient quantity to cover expected demand. We’ll keep you informed through campaign updates as additional arrangements take shape.