Testing components and devices with complex modulation formats require unconventional measurement solutions. Traditional signal sources, for example, may lack the capability to create the advanced phase- and amplitude-based modulation formats used in modern communications systems. But the model 2910 RF vector signal generator from Keithley Instruments (Cleveland, OH) is an unconventional test source with a frequency range—400 to 2500 MHz—that places it in the heart of many modern wireless frequency bands. It also boasts a software-definedradio (SDR) architecture that arms it with the capability to create even the most complex waveforms over the widest modulation bandwidths.
The model 2910 RF vector signal generator is the equivalent of an RF signal generator and separate high-performance modulation source, packed into a compact, half-rack, instrument enclosure. Its RF signal-generation capability includes frequency-switching speed of better than 1 ms for most signals, with a continuous-wave (CW) amplitude range of –120 to +13 dBm and amplitude level accuracy of at least ±0.5 dB and typically ±0.3 dB. The amplitude settling time is also fast, settling to a new level in typically less than 3 ms.
It is the 2910’s modulation capabilities that are most impressive, however, based on an integral arbitrary waveform generator with 64 MSamples capability (256 MB memory). The model 2910 achieves a modulation bandwidth of 40 MHz when using its internal sources. The modulation bandwidth can be increased to 100 MHz through the use of external sources and the 2910’s in-phase (I) and quadrature (Q) input connectors. The 2910 is factory set with a variety of programmed waveforms for most wireless-communications formats, including GSM/GPRS/EDGE, CDMA, and WCDMA, and can readily generate all the traditional modulation formats, including amplitude modulation (AM), frequency modulation (FM), and phase modulation. In addition, the 2910 includes a precision noise source with 2-MHz noise bandwidth for performing quick noise immunity tests.
The highly programmable 2910 is not difficult to use, featuring an intuitive graphical user interface (GUI) that simplifies the generation of elaborate waveforms and speeds the modification of existing waveforms into a desired format. Generated signals are also accurate and noise free. For example, the error vector magnitude (EVM) for EDGE signals is less than 0.5 percent. The 2910 achieves amplitude accuracy of better than 0.5 dB and linearity of better than 0.05 dB to minimize measurement errors.
The 2910, which is at home in both research and production applications, is built into a 3U 5.25 in.) high, half-width housing that is ideal for instrument racks that must harbor a multitude of functions in limited space. The RF vector signal generator is shipped with a collection of tools for developers of remote control software applications such as automatic-test-equipment (ATE) systems. Programmers can develop applications directly on SCPI language or use IVI-COM and IVI-C drivers or modular software building blocks based on the LabVIEW software from National Instruments (www.ni.com).
In signal source features a built-in 100Base-T Ethernet interface as well as a Universal Serial Bus (USB) interface for flexibility in making connections to computers and other equipment. And for older equipment, the 2910 includes a GPIB interface. The instrument supports the emerging LAN eXtensions for Instrumentation (LXI) standards for compatibility with other LXI hardware and software, and includes a sophisticated HELP system that is available off-line and through the GUI to step users through the most complex tasks. Keithley Instruments, Inc., 28775 Aurora Rd., Cleveland, OH 44139; (800) 492-1955 ext. 3910, Internet: www.keithley.com.