A Costas loop is a phase-locked loop (PLL) based circuit which is used for carrier frequency recovery from suppressed-carrier modulation signals (e.g. double-sideband suppressed carrier signals) and phase modulation signals (e.g. BPSK, QPSK). It was invented by John P. Costas at General Electric in the 1950s. Its invention was described as having had "a profound effect on modern digital communications".The primary application of Costas loops is in wireless receivers. Its advantage over other PLL-based detectors is that at small deviations the Costas loop error voltage is as compared to . This translates to double the sensitivity and also makes the Costas loop uniquely suited for tracking Doppler-shifted carriers, especially in OFDM and GPS receivers.
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- Costas loop (en)
- Costas loop (pt)
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| - A Costas loop is a phase-locked loop (PLL) based circuit which is used for carrier frequency recovery from suppressed-carrier modulation signals (e.g. double-sideband suppressed carrier signals) and phase modulation signals (e.g. BPSK, QPSK). It was invented by John P. Costas at General Electric in the 1950s. Its invention was described as having had "a profound effect on modern digital communications".The primary application of Costas loops is in wireless receivers. Its advantage over other PLL-based detectors is that at small deviations the Costas loop error voltage is as compared to . This translates to double the sensitivity and also makes the Costas loop uniquely suited for tracking Doppler-shifted carriers, especially in OFDM and GPS receivers. (en)
- Em telecomunicações, Costas loop é um circuito de phase-locked loop usado para recuperação da fase da portadora de sinais modulados com supressão de portadora. (pt)
- Ein Costas Loop (Deutsch: Costas-Schleife) ist in der digitalen Nachrichtentechnik eine Möglichkeit zur Demodulation von binär phasenmodulierten (BPSK) Signalen. Eine erweiterte Form dieser Schleife kann auch zur Demodulation von quadraturmodulierten (QPSK) Signalen Verwendung finden. Der Costas Loop wurde 1956 von als besondere Variante des Phase-Locked Loops entwickelt. (de)
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| - Ein Costas Loop (Deutsch: Costas-Schleife) ist in der digitalen Nachrichtentechnik eine Möglichkeit zur Demodulation von binär phasenmodulierten (BPSK) Signalen. Eine erweiterte Form dieser Schleife kann auch zur Demodulation von quadraturmodulierten (QPSK) Signalen Verwendung finden. Der Costas Loop wurde 1956 von als besondere Variante des Phase-Locked Loops entwickelt. Bei der Übertragung von phasenmodulierten digitalen Signalen, wie sie beispielsweise im digitalen Mobilfunk Verwendung finden, muss der Empfänger zur Gewinnung des gesendeten Bitdatenstromes die korrekte Phasenlage rekonstruieren können. Der dazu in Empfängern eingesetzte Costas Loop besteht als Kernkomponenten aus einem spannungsgesteuerten Oszillator (VCO, VCXO), einem Schleifenfilter , mehreren Multiplizierern und zwei Tiefpassfiltern. Bei korrekt eingestellter Phasenlage des VCO ist das Steuersignal über den Schleifenfilter 0. Kommt es zu einer Taktabweichung, wird diese durch die Regelschleife nachgeregelt. Am Ausgang der Costas Loop ist bei korrekt eingestellter Phasenlage direkt der gesendete Bitdatenstrom abzugreifen. Der Vorteil des Costas Loop zur digitalen Demodulation von QPSK-Signalen liegt im Gegensatz zur Demodulation mittels Phasenregelschleife (PLL) darin, dass das Phasenrauschen geringer ist und er bei ungünstiger Phasenlage schneller einrastet. Außerdem kann damit das Einrasten (engl. lock) auf falsche Trägerfrequenzen stärker verhindert werden. (de)
- A Costas loop is a phase-locked loop (PLL) based circuit which is used for carrier frequency recovery from suppressed-carrier modulation signals (e.g. double-sideband suppressed carrier signals) and phase modulation signals (e.g. BPSK, QPSK). It was invented by John P. Costas at General Electric in the 1950s. Its invention was described as having had "a profound effect on modern digital communications".The primary application of Costas loops is in wireless receivers. Its advantage over other PLL-based detectors is that at small deviations the Costas loop error voltage is as compared to . This translates to double the sensitivity and also makes the Costas loop uniquely suited for tracking Doppler-shifted carriers, especially in OFDM and GPS receivers. (en)
- Em telecomunicações, Costas loop é um circuito de phase-locked loop usado para recuperação da fase da portadora de sinais modulados com supressão de portadora. (pt)
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