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Amplitude modulation and the first-order phase-locked loop

Research output: Contribution to journalArticle

  • PB Kenington
  • JP McGeehan
  • DJ Edwards
Original languageEnglish
Pages (from-to)17 - 24
Number of pages8
JournalIEE Proceedings I - Communications, Speech and Vision
Journal issue1
StatePublished - Feb 1990


The behaviour of a first-order phase-locked loop is critically examined under conditions where it is tracking a carrier corrupted by discontinuous (square-wave) amplitude modulation. The transient response of the system is first derived for the simple case of a PLL without time delay, and a comparison is made with a series of practical results obtained from a first-order loop. The agreement between the predicted response and that observed in practice is found to be extremely good. The theoretical behaviour of the loop is further analysed for the case of a system incorporating time delay. It is shown that such delay is detrimental to the tracking performance of the loop, when it is necessary to track a carrier modulated in the manner outlined above

Additional information

Publisher: Institute of Electrical Engineers (IEE) Rose publication type: Journal article

Research areas

  • amplitude modulation, phase-locked loops, radio receivers, satellite ground stations, radar and radionavigation, modulation

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