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Software radio PMC delivers 256 DDC channels

Posted: 08 May 2008 ?? ?Print Version ?Bookmark and Share

Keywords:DDC channel? software radio? ADC?

Pentek Inc. has introduced its Model 7151 high-performance, high-resolution software radio module. Four 200MHz 16bit ADCs feed a proprietary FPGA IP core that delivers 256 channels of digital down conversion (DDC). Particularly suited for GSM cellphone monitoring and signal-intelligence applications, the Model 7151 promises the best resolution and highest channel density in the market today.

With independent frequency tuning for each of the 256 DDC channels, the Model 7151 can down-convert any signal within any of the four digitized 100MHz input bands, significantly enhancing the efficiency and diversity of signal-intelligence applications. Arranged in four banks of 64 DDC channels, each bank can be configured for a unique output signal bandwidth to accommodate applications requiring mixed signal types or multiple modulation schemes. Each DDC bank can be independently sourced from any one of the four ADCs, which are typically assigned to specific antennas. As a result, the Model 7151 affords the engineer extreme flexibility for simultaneously capturing hundreds of signals spanning a wide range of modulation types, signal bandwidths and antenna sources.

The front end accepts four +10dBm, full-scale analog RF or IF inputs on front-panel SMC connectors into 50, with transformer couplings to four 200MHz, 16bit ADCs. The digitized outputs are delivered into a Xilinx Virtex-5 FPGA for routing, formatting and DDC signal-processing operations. The 200MHz ADCs accommodate input signal bandwidths of up to 100MHz, representing a 37 percent increase over previous Pentek modules.

The Model 7151 employs an advanced FPGA-based DDC engine comprised of four identical 64-channel DDC banks. Four independently controllable input multiplexers select one of the four ADCs as the input source for each DDC bank. In this way, many different configurations can be achieved, including one ADC driving all 256 DDC channels and each of the four ADCs driving its own DDC bank. Each of the 256 DDCs has an independent 31bit tuning frequency setting that ranges from DC to ?s/2, where ?s is the ADC sampling rate.

All of the 64 channels within a bank share a common decimation setting that can range from 128 to 1024, programmable in steps of 64. For example, with a sampling rate of 200MHz, the available output bandwidths range from 156kHz to 1.25MHz.

Each 64-channel bank can have its own unique decimation setting supporting as many as four different output bandwidths on the board. This flexibility lets customers map the DDC to their own particular application.

The decimating filter for each DDC bank accepts a unique set of user-supplied 18bit coefficients. The 80 percent default filters deliver an output bandwidth of 0.8 ?s/N, where N is the decimation setting. The rejection of adjacent-band components within the 80 percent output bandwidth is better than 100dB. Each DDC delivers a complex output stream consisting of 24bit I and 24bit Q samples at a rate of ?s/N.

Any number of channels can be enabled with each bank, selectable from 0 to 64. Each bank includes an output sample interleaver that delivers a channel-multiplexed stream for all enabled channels within the bank.

Four output MUXs can be independently switched to deliver either ADC data or DDC data into each of the four output FIFOs. This allows users to view either the wideband ADC data or the narrowband DDC data, depending on the application. Each of the output FIFOs operates at its own input rate and output rate to support different DDC decimation settings between the banks and efficient block transfers to the PCI bus.

The 7151 PMC module can be attached to any PMC carrier board. The Model 7651 is a PCI-board version, and it can readily be plugged into a desktop PC. For CompactPCI systems, the 7251 is a 6U module and the 7351 is a 3U module. Pentek will soon be announcing PCIe versions of the module as well.

What's more, a 4207 processor board with its two mezzanine sites can support two 7151 PMCs delivering 512 DDC channels in a single VME slot. Software and software-support packages are available for Linux, Windows and VxWorks operating systems.

Contact the company representative for the latest pricing and availability information.

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