Software radio transceiver provides 256 tunable receive channels

Pentek Inc. announced the blending of its GateFlow 4954-430 high-density, narrowband digital downconverter FPGA IP core with its 7140 software radio transceiver PMC module.

According to the press release, the new 7140-430 software radio transceiver utilizes the core to provide 256 individually tunable receive channels in a full-function PMC/XMC transceiver module. This combination is suited for developers of multi-channel communications systems, such as military radios and commercial wireless base stations that require a high channel density within tight size, weight, cost and power constraints.

"This represents a huge boost in channel density," said Pentek VP Rodger Hosking. "The typical downconverter module offers between four and sixteen narrowband channels. Our new 430 core packs 256 independently tunable DDC receive channels in a single, moderately sized FPGA. By incorporating this core within our Model 7140 PMC/XMC module, we now allow system designers to realize a minimum sixteen-fold improvement in density over previous designs."

The 7140 module's front-end accepts two analog HF inputs and transformer-couples them into 14bit analog-to-digital converters sampling up to 105MHz. The digitized output signals pass to a Virtex-II Pro XC2VP50 FPGA that implements the downconverter core sourced from either channel. A channelizer stage generates 1024 fixed, adjacent, over-lapping frequency channels with alias-free performance greater than 75dB. A 256-output switch matrix follows the channelizer, providing the coarse tuning function.

In addition to coarse tuning, each channel uses its own programmable numerically controlled oscillator to provide fine-tuning and a mixer to translate the signal of interest to baseband. Coarse and fine-tuning details are automatically derived from a single 32bit tuning frequency parameter accepted for each of the 256 channels.

A user-programmable decimating FIR low-pass filter defines output channel bandwidth with decimation settings ranging from 1,024 to 9,984. For an A/D sampling rate of 100MHz, the output bandwidth ranges from about 8kHz to 80kHz.

In addition to the receiver section, the 7140 module offers a transmit section. A digital upconverter translates real or complex baseband signals to any IF center frequency from DC to 160MHz. Two 16bit digital-to-analog converters then produce real or quadrature (I+Q) IF output signals routed through the module's PCI interface.