GB1317255A - Demodulators - Google Patents

Demodulators

Info

Publication number
GB1317255A
GB1317255A GB1317255DA GB1317255A GB 1317255 A GB1317255 A GB 1317255A GB 1317255D A GB1317255D A GB 1317255DA GB 1317255 A GB1317255 A GB 1317255A
Authority
GB
United Kingdom
Prior art keywords
output
oscillator
signal
july
filtered
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Plessey Co Ltd
Original Assignee
Plessey Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Plessey Co Ltd filed Critical Plessey Co Ltd
Publication of GB1317255A publication Critical patent/GB1317255A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
    • H03D3/02—Demodulation of angle-, frequency- or phase- modulated oscillations by detecting phase difference between two signals obtained from input signal
    • H03D3/24—Modifications of demodulators to reject or remove amplitude variations by means of locked-in oscillator circuits
    • H03D3/241—Modifications of demodulators to reject or remove amplitude variations by means of locked-in oscillator circuits the oscillator being part of a phase locked loop
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
    • H03L7/00—Automatic control of frequency or phase; Synchronisation
    • H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
    • H03L7/08—Details of the phase-locked loop
    • H03L7/085—Details of the phase-locked loop concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal
    • H03L7/093—Details of the phase-locked loop concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal using special filtering or amplification characteristics in the loop

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
  • Networks Using Active Elements (AREA)

Abstract

1317255 Frequency demodulators; automatic gain control PLESSEY CO Ltd 8 July 1970 [11 July 1969] 34973/69 Headings H3A and H4R An FM demodulator comprises a variable frequency oscillator 6, a phase comparator 4 providing an output signal for maintaining the oscillator output at a predetermined phase difference with respect to an input FM signal and an arrangement 12, 14 for sensing the comparator output and operative to modify it in a sense to reduce the demodulator band width. The phase comparator 4 is formed by a bi-stable unit, the mark to space ratio of whose output is indicative of the phase difference. The above output is filtered at 10 and applied via a variable attenuator 14 for controlling the oscillator 6. A detector 12 detects the amplitude of the filtered output for adjusting the attenuation offered by 14. The variable attenuator 14 comprises a field effect transistor 24 whose source to drain resistence is controlled by a control voltage at 22 applied via an amplifier 38 linearized by a feedback network including an FET 42. The attenuated signal is applied to the output 18 via a differential amplifier 26 provided with a biasing network 36 and a feed-back arrangement 28- 32.
GB1317255D 1969-07-11 1969-07-11 Demodulators Expired GB1317255A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3497369 1969-07-11

Publications (1)

Publication Number Publication Date
GB1317255A true GB1317255A (en) 1973-05-16

Family

ID=10372292

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1317255D Expired GB1317255A (en) 1969-07-11 1969-07-11 Demodulators

Country Status (1)

Country Link
GB (1) GB1317255A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4471324A (en) * 1982-01-19 1984-09-11 Dbx, Inc. All NPN variably controlled amplifier

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4471324A (en) * 1982-01-19 1984-09-11 Dbx, Inc. All NPN variably controlled amplifier

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Legal Events

Date Code Title Description
PS Patent sealed
PLNP Patent lapsed through nonpayment of renewal fees