Signal capture is an essential part of many military and intelligence systems. With suspect signals lurking within increasingly dense signal environments, high-speed digitizers are needed for reliable signal acquisition and processing. Fortunately, the Acqiris models SVM3500 and SVM4800 VME/VXS format digitizers from Agilent Technologies provide the signalprocessing firepower needed to grab as many as eight channels of signal information over wide input bandwidths.

Both digitizers are designed according to the VXS VITA 41.0 standard for high data throughput. The standard supports eight serial links on a P0 connector at rates to 3.125 Gb/s each, and aggregate throughputs to 2.5 GB/s. The VITA 41.0 standard defines a number of high-speed protocols, including RapidIO, PCIEXPRESS, Infiniband, or Gigabit Ethernet.

The SVM3500 digitizer (see figure) is a four-channel card that can also be used for singleor dual-channel signal acquisition. It operates with 12-b sample rates to 500 MSamples/s per channel or 2 GSamples/s when used with an external power splitter for one channel of signal capture. The card can process 3-dB bandwidths from 1 MHz (the ACcoupled low-frequency limit) to beyond 2 GHz. Input ports employ gold-plated SMA connectors at 50 and feature VSWR of less than 1.50:1 from 10 to 700 MHz. At sampling rates to 500 MSamples/s, the spurious-free dynamic range (SFDR) is typically better than 56 dB for input frequencies to 1 GHz, the total harmonic distortion is typically better than 56 dB, and the signal-to-noise ratio (SNR) is typically better than 61 dB. The effective number of bits (ENOB) is typically 10 b for input frequencies from 10 to 500 MHz and better than 8.7 b for input frequencies from 500 to 925 MHz. For sampling rates to 2 GSamples/s, the SFDR and THD are better than 56 dB while the SNR is typically better than 59 dB. The ENOB is typically more than 9.6 b for inputs from 10 to 500 MHz and typically better than 8.6 b for input frequencies from 500 to 925 MHz.

The SVM3500 digitizer employs four ADS5463 analog-to-digital converters (ADCs) from Texas Instruments with a high-speed clock distribution chipset for precise timing in all signal acquisition modes. An external clock input port provides direct access to the clock distribution network. The network can generate four clocks, either in phase (4 channels at 500 MSamples/s), in anti-phase (equivalent to 2 channels at 1 GSamples/s each), or in quadrature (equivalent to 1 channel at 2 GSamples/s). A finiteimpulse- response (FIR) filter provides frequency-dependent gain and mismatch correction for the ADCs.

The model SVM4800 digitizer provides eight channels of signal processing in the 6U VME/VXS card format, using 14-b, 125-MSamples/s ADCs. It handles a 300-MHz analog input bandwidth and achieves 78-dB SFDR, 68-dB SNR, and 11-b ENOB at 50 MHz. As with the SVM3500, it is ideal for radar and EW system testing. Agilent Technologies, 5301 Stevens Creek Blvd., Santa Clara, CA 95051; (877) 424-4536, (408) 345-8886, FAX: (408) 345-8474, Internet: www.agilent.com.