High-resolution frequency analysis with a small data record

Article Abstract:

Fast Fourier transforms are used widely for discrete-time spectral analysis, but frequency resolution depends on the number of samples available. Model-based spectral analysis (MBSA) derives higher-resolution spectral detail from fewer samples. National Instruments used MBSA to design part of a portable telephone line analyzer for Caller ID. Caller ID information is transmitted between the first and second rings as an analog phase-coherent frequency shift keyed signal at 1,200 bps. The line analyzer decodes the Caller ID signal and determines the date, time, number and name of the calling party. It measures the ringing length, signal level and other parameters by sampling the incoming signal on an on-board 10-bit analog-to-digital converter. MBSAs provide higher spectral resolution with fewer data points, but signals must fit a known parametric model. MBSAs also tend to be more computationally intensive than fast Fourier transforms.

United States, Telephone and telegraph apparatus, Telephone Apparatus Manufacturing, Product development, Telephone Management Systems, Data Monitors & Analyzers, Computer network equipment industry, Network hardware industry, Equipment and supplies, Column, Telecommunications equipment industry, Technology overview, Telephone management device, Network test equipment, National Instruments Corp., Caller ID telephone service, Caller ID, Network diagnostic/test equipment, NATI

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Digital electronics meets its match

Article Abstract:

Acoustooptics, technology whereby ultrasonic waves extending into microwave frequencies modulate a light beam, has become a practical tool for such applications as communications, radar, and electronic warfare surveillance, where digital signal processing cannot accommodate sufficiently high data rates. Advances in components make acoustooptics feasible for such nonmilitary applications as spectrum analysis, and designers of high-data-rate, real-time systems at such companies as Litton, Harris, and Westinghouse are actively exploiting this technology.

Technology, Optoelectronic devices, Optics, Trends, Applications, Industry-Sponsored Research, Acoustics, Spectrometry, technical

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