Signal quality improved with digital down converter IP modules

“Communications engineers reap the benefits of this module with new wider bandwidths, higher A/D sampling rates and the inclusion of Digital Down Converters (DDCs) allowing for IF to baseband conversion for more accurate demodulation,” said Rodger Hosking, Vice President and Co-Founder of Pentek. “This single board solution contains the LNA, RF tuner, digitiser and DDC all in one software radio and data acquisition module,” he added.

RF tuner stage
A front panel SSMC connector accepts L-Band signals between 925 and 2175MHz, typically from an L-Band antenna or an LNB (Low Noise Block). With its programmable LNA, the Maxim MAX2121 tuner directly converts these L-Band signals to IF or baseband using a broadband I/Q analogue downconverter followed by 123MHz low pass anti-aliasing filters.

The two analogue tuner outputs are digitised by two Texas Instruments ADS5463 500MHz 12-bit A/D converters to capture the full 123MHz bandwidth, three times that of Pentek’s previous L-Band tuners.

For best performance, the analogue outputs of the MAX2121 can be used in the IF mode instead of the analogue baseband I+Q mode. In this case, each ADC digitises an IF signal and then delivers it to a DDC to produce perfectly balanced complex I+Q digital baseband samples for enhanced demodulation performance.

Pentek performance acquisition and DDC IP modules
The Model 71791 features two Acquisition IP modules to easily capture and move data. Each module can receive data from either of the two ADCs or a test signal generator. Each Acquisition IP module contains a powerful DDC IP core with decimation values from 2 to 64k, covering a wide range of signal bandwidths. Because of flexible input routing within the Acquisition IP modules, many different configurations can be achieved including one ADCs driving both DDCs or each of the two ADCs driving its own DDC.

An additional benefit of using the IF analogue output mode is that two independent A/D and DDC channels are now available for digitising and downconverting two signals with different centre frequencies and bandwidths.

Boosting performance with the Onyx Architecture
Architectural enhancements in the Onyx family include 4GB of 1600MHz DDR3 memory and a Gen 3 PCIe interface, delivering peak transfer rates up to 8GB/s. The Virtex-7 is very power efficient making it easier to utilise larger FPGAs for adding user supplied IP. Optional LVDS and gigabit serial connections to the Virtex-7 are available for connecting to custom high performance I/O.

Development tools and software support
The Pentek GateFlow FPGA design kit gives users access to the complete factory installed IP at the source code level, allowing them to extend or even replace the built-in functions using the Xilinx Vivado Design Suite. Compared to the older Xilinx ISE tools, Vivado implements custom IP designs up to 4 times faster with a 20% better design density.

Pentek’s GateXpress PCIe configuration manager supports dynamic FPGA reconfiguration through software commands as part of the runtime application. This provides an efficient way to quickly reload the FPGA to slash development time. For deployed environments, GateXpress enables reloading the FPGA without the need to reset the host system, ideal for applications that require dynamic access to multiple processing IP algorithms.

Pentek’s ReadyFlow Board Support Package is available with drivers for Windows and Linux operating systems. The ReadyFlow C-callable library contains a complete suite of initialisation, control and status functions, as well as a rich set of precompiled, ready-to-run-examples to accelerate application development.

With a Pentek 8266 SPARK PC or 8267 SPARK VPX development system, work can begin immediately on applications. The SPARK system saves engineers the time and expense associated with building and testing a development system and ensures optimum performance of Pentek boards. All SPARK development systems come with software and hardware installed and ready for immediate operation.