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Title: Superconductive chirp-transform spectrum analyzer


Spectral analysis over an instantaneous bandwidth of 2.4 GHz was demonstrated, utilizing superconductive dispersive delay lines in a chirp-transform configuration. Two-tone resolution of 43 MHz and + or - 1.2 dB amplitude uniformity was achieved.

Publication Date:
Research Org.:
Massachusetts Inst. of Tech., Lexington (USA). Lincoln Lab.
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 5951605
Report Number(s):
AD-A-162291/9/XAB; JA-5674
Resource Type:
Technical Report
Country of Publication:
United States

Citation Formats

Withers, R.S., and Reible, S.A. Superconductive chirp-transform spectrum analyzer. United States: N. p., 1985. Web.
Withers, R.S., & Reible, S.A. Superconductive chirp-transform spectrum analyzer. United States.
Withers, R.S., and Reible, S.A. Sat . "Superconductive chirp-transform spectrum analyzer". United States. doi:.
title = {Superconductive chirp-transform spectrum analyzer},
author = {Withers, R.S. and Reible, S.A.},
abstractNote = {Spectral analysis over an instantaneous bandwidth of 2.4 GHz was demonstrated, utilizing superconductive dispersive delay lines in a chirp-transform configuration. Two-tone resolution of 43 MHz and + or - 1.2 dB amplitude uniformity was achieved.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Jun 01 00:00:00 EDT 1985},
month = {Sat Jun 01 00:00:00 EDT 1985}

Technical Report:
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  • Chirp filters are described that consist of miniature tapped superconductive stripline. The stripline consists of 40-micron-wide niobium thin films in a spiral pattern on 125-micron-thick silicon wafers, and tapping is effected by backward-wave couplers between neighboring lines. Sophisticated fabrication and packaging techniques have led to a now mature technology. Devices with 2.6-GHz bandwidth and time-bandwidth products of 98 are routinely fabricated that exhibit amplitude errors within a few tenths of a decibel and phase errors within a fractions of a degree of theoretical. In pulse-compression tests, matched amplitude-weighted devices yield peak relative side-lobe levels of -32 dB.
  • The MATLAB language has become a standard for rapid prototyping throughout all disciplines of engineering because the environment is easy to understand and use. Many of the basic functions included in MATLAB are those operations that are necessary to carry out larger algorithms such as the chirp z-transform spectral zoom. These functions include, but are not limited to mathematical operators, logical operators, array indexing, and the Fast Fourier Transform (FFT). However, despite its ease of use, MATLAB's technical computing language is interpreted and thus is not always capable of the memory management and performance of a compiled language. There aremore » however, several optimizations that can be made within the chirp z-transform spectral zoom algorithm itself, and also to the MATLAB implementation in order to take full advantage of the computing environment and lower processing time and improve memory usage. To that end, this document's purpose is two-fold. The first demonstrates how to perform a chirp z-transform spectral zoom as well as an optimization within the algorithm that improves performance and memory usage. The second demonstrates a minor MATLAB language usage technique that can reduce overhead memory costs and improve performance.« less
  • This report analyzes the effects of finite-precision arithmetic on discrete Fourier transforms (DFTs) calculated using the chirp-z transform algorithm. An introduction to the chirp-z transform is given together with a description of how the chirp-z transform is implemented in hardware. Equations for the effects of chirp rate errors, starting frequency errors, and starting phase errors on the frequency spectrum of the chirp-z transform are derived. Finally, the maximum possible errors in the chirp rate, the starting frequencies, and starting phases are calculated and used to compute the worst case effects on the amplitude and phase spectrums of the chirp-z transform.more » 1 ref., 6 figs.« less
  • In the analysis of turbulent flow, the evaluation of simulations is difficult because the results are three-dimensional and transient. We have found that analysis of the power spectra from the nodal time histories provides not only insight into the behavior of the flow, but it is a useful tool in determining the solution`s spatial (grid) and temporal (time step) convergence. We have developed a method and computer code for calculating the power spectrum for any set of equal-interval data. The code is called PWRSPEC. This report documents the method used to calculate the power spectrum, provides guidance on how tomore » use the PWRSPEC code, and includes an example problem that was used for code validation.« less