Winter 2009-2010 Vol. 18, No. 3

Features Built-in Beamformer supports multiboard systems Programmable Power Meter and Threshold Detect per channel Four 200 MHz, 16-bit A/Ds 2 or 4 Channels of DDC Independent DDC tuning and decimation factors for each channel DDC decimation range from 2 to 256 or from 2 to 65536 Default filters offer 0.2 dB ripple and 100 dB rejection LVPECL clock/sync bus for multimodule synchronization

General Information

Model 7153 is a 4-channel, high-speed software radio module designed for processing baseband RF or IF signals. It features four 200 MHz 16-bit A/Ds supported by a high-performance 4-channel DDC (digital downconverter) and a complete set of beamforming functions. With built-in multiboard synchronization, it is ideally matched to the requirements of real-time software radio and radar systems.

A/D Converters

The front end accepts four full-scale analog RF or IF inputs on front panel SMC connectors at +8 dBm into 50 ohms with transformer coupling to four Texas Instruments ADS5485 200 MHz, 16-bit A/Ds.

The digital outputs are delivered into a Xilinx Virtex-5 FPGA for routing, formatting and DDC signal processing operations.

DDC Input Selection and Tuning

The Model 7153 employs an advanced FPGA-based digital downconverter engine consisting of two or four DDC channels. Four independently controllable input multiplexers select one of the four A/Ds as the input source for each DDC channel. In this way, many different configurations can be achieved including one A/D driving all four DDC channels and each of the four A/Ds driving its own DDC bank.

Decimation and Filtering

Each of the four DDC channels can have its own unique decimation setting, supporting as many as four different output bandwidths for the board. The DDC core can be configured in four-channel mode with each channel offering decimations between 2 and 256, or in two-channel mode with each channel having a decimation range of 2 to 65536, for applications that require a wider range of decimations.

The decimating filter for each DDC channel accepts a unique set of user-supplied 18-bit coefficients. The 80% default filters deliver an output bandwidth of 0.8*ƒs/N, where N is the decimation setting. The rejection of adjacent-band components within the 80% output bandwidth is better than 100 dB.

Beamformer

In addition to the DDCs, the 7153 features a complete beamforming subsystem. Each channel contains programmable I & Q phase and gain adjustments followed by a power meter that continuously measures the individual average power output. The time constant of the averaging interval for each meter is programmable up to 8 ksamples. The power meters present average power measurements for each channel in easy-toread registers.

In addition, each channel includes a threshold detector to automatically send an interrupt to the processor if the average power level of any DDC falls below or exceeds a programmable threshold.

A programmable summation block provides summing of any of the four output channels. An additional programmable gain stage compensates for summation change bit growth. A power meter and threshold detect block is provided for the summed output. The output is then directed to the Channel 1 FIFO for reading over PCI-X. For larger systems, multiple 7153's can be chained together via a built-in Xilinx Aurora interface through the P15 XMC connector.

For more information and price quotation on the Model 7153, click here.