Analyzer Captures Broadband Signals

Sept. 1, 2003
This single instrument offers the traits of a spectrum analyzer and a modulation analyzer along with flexible control software to cover a wide range of signal formats.

Wideband signals common to modern communications systems, such as wideband code-division-multiple-access (WCDMA) signals, tax the limits of even the best spectrum analyzers. For that reason, the engineers at Advantest America Measuring Solutions (Edison, NJ) have developed a hybrid instrument that combines spectrum and modulation analyzers with vector signal generator and arbitrary waveform generator. These hardware tools, together with a series of "plug-in" software modules, make the R3681 signal analyzer one of the most complete tools for evaluating broadband communications signals as high as 32 GHz.

As a conventional spectrum analyzer, the R3681 features a frequency range of 20 Hz to 32 GHz. Resolution bandwidths can be set from 1 Hz to 10 MHz. As a modulation analyzer, the R3681 has a frequency range of 20 Hz to 6 GHz. The general level accuracy is better than ±0.73 dB from 50 MHz to 2.5 GHz with 10 dB attenuation and 100-kHz resolution bandwidth.

The R3681 exhibits excellent spectral purity, with phase noise of −120 dBc/Hz offset 10 kHz from the carrier and −155 dBc/Hz offset 10 MHz from the carrier. The average displayed noise level is −158 dBm at 1 GHz. At the other end of the dynamic range, the analyzer offers a typical 1-dB compression point of +10 dBm from 200 MHz to 3.5 GHz and a third-order intercept point of typically +26 dBm from 2 to 3.5 GHz.

The analyzer's large touch-sensitive display screen, flexible controls, and modular software make it easy to use. Its Wizard Module Test (WMT) system platform makes it possible to add and replace extension modules for different requirements, with modules for signal generation (SG), arbitrary waveform generation (AWG), and wideband modulation analysis (WBA). The analyzer features an adjacent-channel-leakage-power (ACLP) level of −84 dBc for one-carrier measurements with a 5-MHz offset and ACLR level of −77 dBc for four-carrier measurements with a 5-MHz offset.

The R3681 can be equipped with an option (68) for performing offset frequency-division multiplex (OFDM) modulation analysis for IEEE 802.11a WLANs, which supports automatic detection of BPSK, QPSK, 16QAM, and 64QAM modulation formats. P&A: $68,900 (R3681) and $9900 (OFDM option); 6 wks. Advantest America Measuring Solutions, Inc., 258 Fernwood Ave., Edison, NJ 08837; (732) 346-2600, FAX: (732) 346-2610, Internet:

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