Agilent N9000A CXA signal analyzer
In the early days of ATSC VSB transmission, the only option for checking the quality of the signal was the Hewlett Packard 89441 vector signal analyzer. Tektronix soon followed with their RFA-300 analyzer, but the HP 89441 became the standard. The HP 89441—a huge, heavy, expensive and complicated piece of equipment—is seldom used today. It has been replaced by simpler and smaller devices with greater functionality, such as the new Rohde and Schwarz ETL analyzer.
In reading a description of Agilent's new “X-series” analyzers, I realized that it now has a product which could put it back in the broadcast VSB measurement business. (Agilent was created when Hewlett Packard spun off its test equipment business.) The base price of the entry level N9000A-503 CXA signal analyzer is $12,657 for a unit capable of operating up to 3.0 GHz.
These units provide basic spectrum analyzer capability and are capable of running Agilent's 89600 vector signal analysis software. The VXA measurement application with Option AYA provides modulation analysis format capabilities which include PSK, QAM, MSK, EDGE, FSK, VSB, DVBQAM and APSK. The instrument also provides a complete set of modulation quality measurements, including overall EVM, peak EVM, EVM vs. symbol time, EVM spectrum, time, spectrum, constellation diagram, vector diagram, IQ parameters, frequency and clock error and channel vs. impulse response with EQ filter.
With the appropriate options the CXA can also perform channel power measurements, AM and PM demodulation, along with noise-figure measurements. Refer to the Agilent CXA Single Analyzer N9000A data sheet [PDF]for more information.
Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.
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