Pentek Adds 256-Channel DDC To Software Radio Transceiver Module
"This represents a huge boost in channel density," says Rodger Hosking, vice president of Pentek, Inc. "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. This not only slashes the cost per channel but also opens up new applications for multi-channel receivers where space is restricted, such as in unmanned aerial vehicles and portable or concealed signal-intelligence systems." Hosking added, "We created a special version of the 430 core fully optimized for maximum performance and function within the 7140 PMC module. Since we install this core at the factory, our customers can take immediate advantage of its capabilities right out of the box, fully supported with software libraries and drivers. In this way, engineers can reap the benefits of leading-edge FPGA performance with zero FPGA development effort."
The 7140 module's front end accepts two analog HF inputs and transformer-couples them into 14-bit A/D converters sampling up to 105 MHz. 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 75 dB. 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 (NCO) 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 32-bit 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 1024 to 9984. For an A/D sampling rate of 100 MHz, the output bandwidth ranges from about 8 kHz to 80 kHz, suited for most voice or data systems. Baseband outputs pass through a programmable gain stage before being rounded to their final 16-bit result. Each channel has an independently programmable 16-bit gain control.
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 160 MHz. Two 16-bit D/A converters then produce real or quadrature (I+Q) IF output signals routed through the module's PCI interface.
Pentek currently supports the Model 7140-430 with Linux drivers and plans to release Windows, VxWorks and ReadyFlow libraries and drivers in the future. Model 7140-430 functionality is also available in a variety of other form factors including Model 7240-430 (6U cPCI), Model 7340-430 (3U cPCI) and Model 7640-430 (PCI).
SOURCE: Pentek