First VPX GSM monitoring receiver

Paul Boughton

Pentek has developed the industry’s first full spectrum GSM channeliser 3U VPX module.

Using a highly-optimised IP core for the Xilinx Virtex-6 FPGA, the Model 52663 is aimed at mobile monitoring systems that must capture some or all of the 1100 uplink and downlink signals in both upper and lower GSM bands. This full global system for mobile communications spectrum monitoring targets homeland security, government and military applications.

“Platform developers now have a single, dedicated module for monitoring all GSM signals,” said Rodger Hosking, vice president of Pentek. “Many threat scenarios require GSM phone signal interception for detection, analysis and classification, and now for the first time, a single device makes these functions possible for mobile and rugged platforms.”

The Model 52663 accepts four analogue inputs from an external analogue RF tuner such as the Pentek Model 8111, where the GSM RF bands are down converted to an IF frequency. These IF signals are then digitised by four A/D converters and routed to four channelizer banks, which perform digital downconversion of all GSM channels to baseband, all of which can now be housed in a VPX chassis. Two of the banks handle 175 channels for the lower GSM transmit/receive bands and two banks handle 375 channels for the upper bands. The DDC channels within each bank are equally spaced at 200kHz.

Each DDC output is re-sampled to a 4x symbol rate of 1.08333 MHz to simplify symbol recovery. Every four DC outputs are combined into a frequency-division ‘superchannel’ that allows transmission of all 1100 channels across the PCIe Gen 2x8 interface.

The GSM channeliser IP core is supported with additional factory-installed FPGA functions including packet formation, time stamping, four DMA controllers, gating and triggering. Baseband super-channel packets are sent via DMA controllers to processor memory where customers apply processing algorithms.

The 3U VPX form factor of the Model 52663 is ideal for mobile platforms. Ground or airborne monitoring platforms can now scan the entire GSM spectrum for all uplink and downlink signals. The small size and complete spectrum coverage makes it easier to deploy small systems near cell phone towers. Rugged and conduction cooled packages address the needs of extreme environment platforms.

Pentek’s ReadyFlow Board Support Package for Linux and Windows operating systems feature drivers and high-level C-callable library functions to control all aspects of the module.

The Model 52663 3U VPX board is available in ruggedised and conduction-cooled versions. The Model 53663 3U VPX module includes a crossbar switch to support additional PCI Express backplane routing options. The board is also available as an XMC module, Model 71663, designed for both rugged and commercial environments; in cPCI, Models 73663,72663 and 74663; in AMC, Model 56663; and in PCIe, Model 78663. 

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