GB1427029A - Radio receiving apparatus - Google Patents

Radio receiving apparatus

Info

Publication number
GB1427029A
GB1427029A GB5774672A GB5774672A GB1427029A GB 1427029 A GB1427029 A GB 1427029A GB 5774672 A GB5774672 A GB 5774672A GB 5774672 A GB5774672 A GB 5774672A GB 1427029 A GB1427029 A GB 1427029A
Authority
GB
United Kingdom
Prior art keywords
speech
output
signal
gate
supplied
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
GB5774672A
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.)
CUNARD STEAM SHIP
Original Assignee
CUNARD STEAM SHIP
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 CUNARD STEAM SHIP filed Critical CUNARD STEAM SHIP
Priority to GB5774672A priority Critical patent/GB1427029A/en
Publication of GB1427029A publication Critical patent/GB1427029A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers
    • H03G3/20—Automatic control
    • H03G3/30—Automatic control in amplifiers having semiconductor devices
    • H03G3/34—Muting amplifier when no signal is present or when only weak signals are present, or caused by the presence of noise signals, e.g. squelch systems
    • H03G3/342—Muting when some special characteristic of the signal is sensed which distinguishes it from noise, e.g. using speech detector

Landscapes

  • Noise Elimination (AREA)

Abstract

1427029 Radio receiving systems COWARD STEAM-SHIP CO Ltd 13 March 1974 [14 Dec 1972] 57746/72 Heading H4L Radio receiving apparatus includes means for detecting a speech signal below the white noise level, means for generating a signal for the exact duration of the speech signal and a gate in the audio-frequency channel, the generated signal being used to open the gate for the period of the speech signal whereby the white noise is muted between speech syllables. As shown in Fig. 1 the audio signal from the radio receiver is supplied via terminal 30 and the gate 26 to the output stage 28 and via amplifier 10 to rectifiers 12, 14. The outputs of rectifiers 12, 14 are supplied to circuits 16, 18 respectively, circuit 16 having a short time constant so that its output rises quickly when a speech syllable appears and follows the speech signal and circuit 18 having a long time constant so that its output adjusts slowly with changing noise level and it has substantially no response to speech syllables. These two outputs are compared at 20 and when there is no speech present they are equal and the output of the comparator is "0". As soon as the first syllable of speech occurs the output of 16 rises rapidly to switch the comparator to its "1" state. The output of the comparator is a square wave for the duration of the syllable, which is shaped by rounding off the corners at 22 and supplied as a control signal to the gate 26. The output from 20 is also supplied to a gate 24 to prevent the output of circuit 18 from being affected by the speech signal.
GB5774672A 1972-12-14 1972-12-14 Radio receiving apparatus Expired GB1427029A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB5774672A GB1427029A (en) 1972-12-14 1972-12-14 Radio receiving apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB5774672A GB1427029A (en) 1972-12-14 1972-12-14 Radio receiving apparatus

Publications (1)

Publication Number Publication Date
GB1427029A true GB1427029A (en) 1976-03-03

Family

ID=10479933

Family Applications (1)

Application Number Title Priority Date Filing Date
GB5774672A Expired GB1427029A (en) 1972-12-14 1972-12-14 Radio receiving apparatus

Country Status (1)

Country Link
GB (1) GB1427029A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4099127A (en) * 1975-12-29 1978-07-04 Elliott Brothers (London) Limited Audio frequency automatic muting arrangement
EP0010022A1 (en) * 1978-09-29 1980-04-16 Thomson-Csf Device for conditioning speech signals and transmitter comprising such a device
US4506381A (en) * 1981-12-29 1985-03-19 Mitsubishi Denki Kabushiki Kaisha Aural transmitter device

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4099127A (en) * 1975-12-29 1978-07-04 Elliott Brothers (London) Limited Audio frequency automatic muting arrangement
EP0010022A1 (en) * 1978-09-29 1980-04-16 Thomson-Csf Device for conditioning speech signals and transmitter comprising such a device
FR2437744A1 (en) * 1978-09-29 1980-04-25 Thomson Csf DEVICE FOR PROCESSING VOICE MODULATION SIGNALS AND TRANSMITTER COMPRISING SUCH A DEVICE
US4506381A (en) * 1981-12-29 1985-03-19 Mitsubishi Denki Kabushiki Kaisha Aural transmitter device

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Legal Events

Date Code Title Description
PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee