Wireless-communications systems rely on advanced signal-modulation formats for efficient use of limited channel bandwidths. But as those modulation formats grow in complexity, they also increase the measurement challenges. Fortunately, Anritsu Co. (www.us.anritsu.com) has developed a trio of signal analyzers with the wide modulation bandwidths needed for wireless-communications testing. The models MS2690A, MS2691A, and MS2692A have frequency ranges of 50 Hz to 6 GHz, 13.5 GHz, and 26.5 GHz, respectively, each with excellent amplitude accuracy and scads of built-in measurement functions. In addition to operating as spectrum analyzers, the instruments offer vector-signal-analysis (VSA) functions through 6 GHz and perform Fast Fourier Transforms (FFTs) at bandwidths as wide as 125 MHz.

The model MS2690A Signal Analyzer (see figure), for example, is ideal for the majority of wireless-communications testing. Based on an innovative fundamental- frequency downconversion scheme that eliminates the need for preselection filtering over its frequency range of 50 Hz to 6 GHz, the MS2690A (and its two higher-frequency counterparts) incorporates an advanced architecture with two built-in calibration oscillators. A phase-calibration oscillator compensates for intermediatefrequency (IF) filter variations, while a 50-Hz-to-6-GHz level calibration oscillator contributes to the MS2690A's amplitude accuracy of ±0.5 dB.

As a VSA, the MS2690A features with 1-Hz frequency resolution and analysis bandwidths that can be set from 1 kHz to 25 MHz; an additional wideband setting arms the MS2690A with a 31.25- MHz analysis bandwidth. As a traditional spectrum analyzer, resolutionbandwidth filters can be set from 30 Hz to 3 MHz (in a 1-3 sequence) and at 5, 10, and 20 MHz. Video bandwidths can be set from 1 Hz to 10 MHz. Frequency spans for all instruments run from 300 Hz to the full bandwidth of the analyzer; all three offer zero-span measurements.

For assisting with amplitude measurements, reference levels in the MS2690A can be set from -120 to +5 dBm. The input power range can be further extended with the help of a built-in 0-to-60-dB attenuator that can be adjusted in 2-dB steps.

The MS2690A, MS2691A, and MS2692A analyzers provide a plethora of automatic measurements and display functions. The analyzers offer measurements and displays of constellation information, spectrum versus subcarrier, and power versus time for uplink and downlink signals, as well as screens showing map information, spectral flatness, error vector versus symbol, error vector versus subcarrier, and I/Q data versus subcarrier for downlink signals.

For specific wireless tests, the MS2690A is supported by several software tools. These include the MX269010A Mobile WiMAX Measurement Software for automated measurements on mobile WiMAX uplink/downlink signals from 2.3 to 3.8 GHz and the MX269030A WCDMA BS Measurement software for WCDMA base stations (BS) from 400 MHz to 3 GHz. Anritsu Co., 1155 East Collins Blvd., Suite 100, Richardson, TX 75081; (800) ANRITSU (267-4878), (972) 644-1777, FAX: (972) 671-1877, Internet: www.us.anritsu.com.