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Software radio system tags digital transceiver

Posted: 12 Nov 2007 ?? ?Print Version ?Bookmark and Share

Keywords:software radio? Pentek digital transceiver? multiband DDC?

Pentek Inc. introduces the Model 7142-428 digital transceiver with a multiband digital downconverter (DDC) and interpolation filter. The device offers a complete software radio system in a COTS PMC/XMC module.

The Model 7142-428 uses four ADCs and one DAC capable of bandwidths exceeding 40MHz for connection to HF and IF ports of communications or radar systems. Signal bandwidths range from 8kHz to 40MHz, which includes voice-band systems to 1G, 2G, 3G and emerging 4G wireless waveforms.

In a transceiver, the decimation factor and interpolation factor determine the ratio between the IF frequency and the bandwidth of the received and transmitted signals, said Pentek. This digital transceiver delivers a decimation range from 2 to 65,536 and an interpolation range from 2 to 32,768, enabling the device to address a variety of commercial and military communication systems.

Each of the four DDCs in the 428 IP core is implemented as two cascaded DDC stages, each with a programmable decimation of 1 to 256. Because the decimations from the two stages multiply, users can choose an overall decimation anywhere from 2 to 65,536. As a result, each of these "multiband" DDC cores spans the decimation range of both wideband and narrowband DDCs, all in a single device, said Pentek.

The four down-converted DDC outputs are delivered to the PCI interface through independent FIFOs, each managed by its own DMA controller channel to simplify programming and improve data transfer rates.

Four 14-bit ADCs at the front end operate at sample rates up to 125MHz. Each of the four identical DDC engines uses an independent 4-input multiplexer to select any one of these four ADCs as its input source. The four DDCs feature independent tuning and decimation to translate any frequency band at the input down to zero frequency.

For upconverting, a Texas Instruments DAC5686 offers a 500MHz,16bit DAC and a digital upconverter (DUC) operating at a sample rate of up to 320MHz. The DUC offers a built-in interpolation range of only x2 to x16. The 428's IP core interpolation filter extends this limited range of interpolation by an additional factor of x2 to x2048, providing an overall range of x2 to x32768, said Pentek. After interpolation, the DUC can be tuned to translate the baseband transmit signal frequency to any IF output frequency up to 140MHz.

All of the new 428 IP core functions are fully supported by Pentek's ReadyFlow Board Support Packages.

- Gina Roos

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