Closed-loop autocorrelator and its application to fequency discrimination

H. Messer, H. Messer, Y. Bar-Ness, Y. Bar-Ness

Research output: Contribution to journalArticlepeer-review


A new closed-loop autocorrelation system is proposed in the paper. It is based on a conventional autocorrelator; however, the fixed delay is replaced by a variable delay line and the autocorrelator output is fed back to control the delay. The variable delay can be realised by a SAW voltage-controlled variable delay line (VCDL). A detailed analysis of the loop is given. It is shown that for some special inputs, the loop performs as a frequency-measuring system, as an instantaneous frequency measurement (IFM) or as a wideband linear FM discriminator. It is further shown that, in the presence of noise, the loop behaves similarly to a frequency modulation feedback (FMFB) loop. Therefore, the output SNR can be improved (in comparison with conventional FM discriminators) by appropriately choosing the loop parameters. Experimental results of a system implemented using an SAW VCDL are presented and are shown to support the analysis.

Original languageEnglish
Pages (from-to)25-33
Number of pages9
JournalIEE Proceedings, Part F: Communications, Radar and Signal Processing
Issue number1
StatePublished - 1986


  • Delay lines
  • Signal processing
  • Surface-acoustic-wave devices


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