GB2052196A - Demodulators - Google Patents

Demodulators Download PDF

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Publication number
GB2052196A
GB2052196A GB7922417A GB7922417A GB2052196A GB 2052196 A GB2052196 A GB 2052196A GB 7922417 A GB7922417 A GB 7922417A GB 7922417 A GB7922417 A GB 7922417A GB 2052196 A GB2052196 A GB 2052196A
Authority
GB
United Kingdom
Prior art keywords
phase quadrature
demodulator
signals
mixers
fed
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.)
Withdrawn
Application number
GB7922417A
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
Priority to GB7922417A priority Critical patent/GB2052196A/en
Priority to IL60172A priority patent/IL60172A0/en
Priority to IT22867/80A priority patent/IT1131352B/en
Priority to BR8003834A priority patent/BR8003834A/en
Priority to NL8003663A priority patent/NL8003663A/en
Priority to JP8639280A priority patent/JPS568944A/en
Priority to DE19803023773 priority patent/DE3023773A1/en
Priority to FR8014227A priority patent/FR2460069A1/en
Priority to DK275980A priority patent/DK275980A/en
Publication of GB2052196A publication Critical patent/GB2052196A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/54—Circuits using the same frequency for two directions of communication
    • H04B1/56—Circuits using the same frequency for two directions of communication with provision for simultaneous communication in two directions
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
    • H03D7/16—Multiple-frequency-changing
    • H03D7/165—Multiple-frequency-changing at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature
    • H03D7/166—Multiple-frequency-changing at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature using two or more quadrature frequency translation stages
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D7/00—Transference of modulation from one carrier to another, e.g. frequency-changing
    • H03D7/16—Multiple-frequency-changing
    • H03D7/161—Multiple-frequency-changing all the frequency changers being connected in cascade
    • H03D7/163—Multiple-frequency-changing all the frequency changers being connected in cascade the local oscillations of at least two of the frequency changers being derived from a single oscillator
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/403—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency
    • H04B1/408—Circuits using the same oscillator for generating both the transmitter frequency and the receiver local oscillator frequency the transmitter oscillator frequency being identical to the receiver local oscillator frequency

Abstract

A demodulator of the kind which receives a pair of phase quadrature related signals carrying in combination data to be demodulated comprising a pair of multiplicative mixers 17, 18 to which the phase quadrature related signals are fed, one to each mixer, a phase quadrature device 20, a local oscillator 19 arranged to feed the mixers with local oscillator signals via the phase quadrature device so that the local oscillator signals received by respective mixers are in phase quadrature, a combiner to which output signals from the mixers are fed and a detector 22 fed from the combiner for providing an output signal corresponding to the modulation carried by the phase quadrature related signals. The demodulator may form part of a common channel duplex transceiver for AM or FM reception having a diode detector or Foster-Seeley discriminator. A modulator 7 is also fed with an output from an oscillator 5 which feeds in quadrature a pair of multiplicative mixers 3, 4 at the input of the transceiver. <IMAGE>

Description

SPECIFICATION Improvements in or relating to demodulators This invention relates to demodulators more especially it relates to demodulators of the kind which receive a pair of phase quadrature related signals carrying in combination data to be demodulated.
The invention is especially although not exclusively applicable to an FM common channel duplex transceiver as described in our G.B. Patent Application No. 10360/76 (Serial No 1577514) or to an a.m. common channel duplex transceiver as described in our co-pending patent application No.
According to the present invention a demodulator of the kind which receives a pair of phase quadrature related signal carrying in combination data to be demodulated, comprises a pair of multiplicative mixers to which the phase quadrature related signals are fed one to each mixer, a phase quadrature device, a local oscillator arranged to feed the mixers with local oscillator signals via the phase quadrature device so that the local oscillator signals received by respective mixers are in phase quadrature, combiner means to which output signals from the mixers are fed and detector means fed from the combiner means and providing an output signal corresponding to the modulation carried by the phase quadrature related signals.
The kind of detector means used will be chosen in accordance with the character of the modulation carried by the phase quadrature related signals.
According to one embodiment of the invention, for the detection of an a.m. modulated signal carried by the phase quadrature related signals the detector means comprises an envelope detector which may simply comprise a diode detector.
According to another embodiment of the invention, for the detection of f.m. modulation carried by the phase quadrature related signals the detector means comprises an f.m descriminator or ratio detector adapted to demodulate frequency modulation which deviates about a centre frequency corresponding to the frequency of the said oscillator.
According to the said one embodiment of the invention the demodulator means may form a part of a common channel duplex transceiver suitable for a.m. reception and as described in our copending patent application No.
According to the other embodiment of the invention the demodulator means may form a part of a common channel duplex transceiver suitable for FM reception as claimed in and/or as described in our U.K. Patent Application No. 10360/76.
(Serial No 1577514) Some embodiments of the invention will now be described by way of example with reference to the accompanying drawing which is a generally schematic block diagram of a common channel duplex transceiver embodying a demodulator.
Referring now to the drawing the transceiver comprises a receiving aerial 1 signals from which are fed via a duplexer 2 to a pair of multiplicative mixers 3 and 4. The mixers are fed with a local oscillator signal from an oscillator 5, the mixer 3 being fed with signals from the local oscillator via a phase quadrature device 6 whereby local oscillator signals fed to the mixers 3 and 4 are in phase quadrature. Output signals for transmission are fed from the oscillator 5 to a modulator 7 which receives modulation signals on line 8 and provides output signals for transmission which are fed to an aerial 9. Output signals from the mixer 3 are fed via a low pass filter 10 and an amplifier 1 1 to one port 12 of a demodulator shown within the broken line 13.Output signals from the mixer 4 are fed via a low pass filter 14 and an amplifier 15 to the other port 16 of the demodulator shown within the broken line 13. The demodulator comprises a pair of multiplicative mixers 17 and 1 8 which receive phase quadrature related signals from the input ports 12 and 16 respectively and to which are fed phase quadrature related local oscillator signals from a local oscillator 19 and a phase quadrature device 20. Output signals from the mixers 17 and 18 are fed to an additive combiner 21 and output signals from the combiner are fed to a detector 22 which provides on an output line 23 a signal corresponding to the modulation carried by signals received at the aerial 1.
The nature of the detector 22 will be chosen in dependence upon the kind of modulation received at the aerial 1. Thus for f.m. reception a descriminator such as a Foster-Seeley descriminator may be used or alternatively for f.m.
a ratio detector may be used. For the reception of a.m. modulation the detector 22 may comprise any form of envelope detector such as a simple diode detector. Such a.m. and f.m. detectors are well known to those skilled in the art and will not be described herein in detail.
It will be appreciated that the present invention is concerned more especially with the provision of a demodulator and therefore operation of the main part of the common channel duplex transceiver has not been shown in detail and will not be described herein. Attention is however directed to our co-pending U.K. Patent Application Nos.
10360/76 (Serial No 1577514) and in which am and f.m. common channel duplex transceivers respectively are fully described. A demodulator of the kind which forms the subject of the present invention operates to synthesise from the phase quadrature related signals fed to the ports 12 and 16 a carrier frequency which is a replica of the signal received at the aerial 1 in all respects but which deviates for f.m signals about the frequency of the local oscillator 19. In one embodiment the frequency of the oscillator 5 might be 100 Mhz whereas the frequency of the local oscillator 19 might conveniently be .5Mhz. For the reception of frequency modulated signals, as the input frequency changes at 12 and 16, the side bands present in the combiner 21 move apart with respect to a centre frequency corresponding to the frequency of the local oscillator 19. In contradistinction, if the local oscillator 1 9 frequency changes, it can be shown that the side bands move together with respect to a centre frequency corresponding to the frequency of the local oscillator 1 9.

Claims (7)

1. A demodulator of the kind which receives a pair of phase quadrature related signals carrying in combination data to be demodulated comprising a pair of multiplicative mixers to which the phase quadrature related signals are fed, one to each mixer, a phase quadrature device, a local oscillator arranged to feed the mixers with local oscillator signals via the phase quadrature device so that the local oscillator signals received by respective mixers are in phase quadrature, combiner means to which output signals from the mixers are fed and detector means fed from the combiner means for providing an output signal corresponding to the modulation carried by the phase quadrature related signals.
2. A demodulator as claimed in claim 1 wherein the detector means comprises an envelope detector for the detection of a.m. modulated signals carried by the phase quadrature related signals.
3. A demodulator as claimed in claim 1 wherein the detector means comprises an f.m.
discriminator or ratio detector adapted to demodulate frequency demodulation which deviates about a centre frequency corresponding to the frequency of the said oscillator.
4. A common channel duplex transceiver suitable for a.m. reception as claimed in our copending patent application No. 7922701 and including a demodulator as claimed in any preceding claim.
5. A common channel duplex transceiver suitable for f.m. reception as claimed in or as described in our U.K. patent application No.
10360/76 (Serial No 1577514) and including a demodulator as claimed in any of claims 1 to 4.
6. A demodulator as hereinbefore described with reference to the accompanying drawings.
7. A common channel duplex transceiver including a demodulator as claimed in claim 6.
GB7922417A 1979-06-27 1979-06-27 Demodulators Withdrawn GB2052196A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
GB7922417A GB2052196A (en) 1979-06-27 1979-06-27 Demodulators
IL60172A IL60172A0 (en) 1979-06-27 1980-05-27 Demodulator
IT22867/80A IT1131352B (en) 1979-06-27 1980-06-18 DEMODULATOR
BR8003834A BR8003834A (en) 1979-06-27 1980-06-19 DEMODULATOR
NL8003663A NL8003663A (en) 1979-06-27 1980-06-24 DEMODULATOR.
JP8639280A JPS568944A (en) 1979-06-27 1980-06-25 Demodulator
DE19803023773 DE3023773A1 (en) 1979-06-27 1980-06-25 DEMODULATOR
FR8014227A FR2460069A1 (en) 1979-06-27 1980-06-26 DEMODULATOR THAT RECEIVES A PAIR OF QUADRATURE SIGNALS AND IS PART OF A COMMON CHANNEL DUPLEX TRANSCEIVER AND THE TRANSCEIVER EQUIPPED WITH THE SAME
DK275980A DK275980A (en) 1979-06-27 1980-06-26 DEMODULATOR

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB7922417A GB2052196A (en) 1979-06-27 1979-06-27 Demodulators

Publications (1)

Publication Number Publication Date
GB2052196A true GB2052196A (en) 1981-01-21

Family

ID=10506144

Family Applications (1)

Application Number Title Priority Date Filing Date
GB7922417A Withdrawn GB2052196A (en) 1979-06-27 1979-06-27 Demodulators

Country Status (9)

Country Link
JP (1) JPS568944A (en)
BR (1) BR8003834A (en)
DE (1) DE3023773A1 (en)
DK (1) DK275980A (en)
FR (1) FR2460069A1 (en)
GB (1) GB2052196A (en)
IL (1) IL60172A0 (en)
IT (1) IT1131352B (en)
NL (1) NL8003663A (en)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0122657A1 (en) * 1983-04-01 1984-10-24 Koninklijke Philips Electronics N.V. Receiver for RF signals comprising a pair of parallel signal paths
EP0124949A1 (en) * 1983-05-10 1984-11-14 Koninklijke Philips Electronics N.V. Mixer arrangement comprising first and second quadrature mixer stages
US4499426A (en) * 1980-07-02 1985-02-12 Motorola, Inc. Baseband discriminator for frequency or transform modulation
EP0160484A2 (en) * 1984-04-23 1985-11-06 Nec Corporation FM receiver including a baseband PLL circuit
AT394918B (en) * 1990-04-05 1992-07-27 Klaus Dipl Ing Dr Kerschbaumer METHOD FOR DIRECTLY DEMODULATING AN RF SIGNAL
EP0533435A1 (en) * 1991-09-18 1993-03-24 Nec Corporation Radio telephone apparatus with frequency divider used during emission and stopped during reception
US5389964A (en) * 1992-12-30 1995-02-14 Information Resources, Inc. Broadcast channel substitution method and apparatus
US5404161A (en) * 1993-07-27 1995-04-04 Information Resources, Inc. Tuned signal detector for use with a radio frequency receiver
GB2300318A (en) * 1981-02-10 1996-10-30 Plessey Co Ltd Improvements in or relating to transceivers
FR2794311A1 (en) * 1999-05-27 2000-12-01 France Telecom CARRIER FREQUENCY REDUCING PASSET FILTER
GB2380641A (en) * 2001-09-14 2003-04-09 Roke Manor Research common channel transceiver, which can reduce the noise from the transmitter antenna, appearing on the receiver antenna by using a digital filtering stage
US6941573B1 (en) 1996-08-07 2005-09-06 Information Resources, Inc. Television distribution system for signal substitution
US8005439B2 (en) 1997-02-20 2011-08-23 Telefonaktiebolaget L M Ericsson (Publ) Radio transceiver on a chip

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1178539A (en) * 1966-12-14 1970-01-21 Plessey Btr Ltd Improvements in Timing Arrangements for Electrical Signalling Systems
US3577088A (en) * 1969-02-03 1971-05-04 Us Air Force Sine-cosine to magnitude-phase angle converter
DE2358288A1 (en) * 1973-11-22 1975-06-05 Standard Elektrik Lorenz Ag RECEIVER FOR FREQUENCY-MODULATED HF SIGNALS
FI67641C (en) * 1976-03-16 1985-04-10 Plessey Overseas SAENDAR / MOTTAGARE MED GEMENSAM KANAL

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4499426A (en) * 1980-07-02 1985-02-12 Motorola, Inc. Baseband discriminator for frequency or transform modulation
GB2300318B (en) * 1981-02-10 1997-03-19 Plessey Co Ltd Improvements in or relating to transceivers
GB2300318A (en) * 1981-02-10 1996-10-30 Plessey Co Ltd Improvements in or relating to transceivers
EP0122657A1 (en) * 1983-04-01 1984-10-24 Koninklijke Philips Electronics N.V. Receiver for RF signals comprising a pair of parallel signal paths
US4814715A (en) * 1983-05-10 1989-03-21 U.S. Philips Corporation Mixer arrangement for suppression of oscillator interference in quadrature demodulators
AU573139B2 (en) * 1983-05-10 1988-05-26 Philips Electronics N.V. Quadrature mixer
EP0124949A1 (en) * 1983-05-10 1984-11-14 Koninklijke Philips Electronics N.V. Mixer arrangement comprising first and second quadrature mixer stages
EP0160484A2 (en) * 1984-04-23 1985-11-06 Nec Corporation FM receiver including a baseband PLL circuit
EP0160484A3 (en) * 1984-04-23 1987-04-29 Nec Corporation Fm receiver including a baseband pll circuit
AT394918B (en) * 1990-04-05 1992-07-27 Klaus Dipl Ing Dr Kerschbaumer METHOD FOR DIRECTLY DEMODULATING AN RF SIGNAL
EP0533435A1 (en) * 1991-09-18 1993-03-24 Nec Corporation Radio telephone apparatus with frequency divider used during emission and stopped during reception
US5553317A (en) * 1991-09-18 1996-09-03 Nec Corporation Quadrature modulator for TDMA/TDD radio communication apparatus
US5389964A (en) * 1992-12-30 1995-02-14 Information Resources, Inc. Broadcast channel substitution method and apparatus
US5404161A (en) * 1993-07-27 1995-04-04 Information Resources, Inc. Tuned signal detector for use with a radio frequency receiver
US6941573B1 (en) 1996-08-07 2005-09-06 Information Resources, Inc. Television distribution system for signal substitution
US8005439B2 (en) 1997-02-20 2011-08-23 Telefonaktiebolaget L M Ericsson (Publ) Radio transceiver on a chip
US8626086B2 (en) 1997-02-20 2014-01-07 Telefonaktiebolaget L M Ericssson (Publ) Radio transceiver on a chip
US8954020B2 (en) 1997-02-20 2015-02-10 Telefonaktiebolaget L M Ericsson (Publ) Radio transceiver on a chip
FR2794311A1 (en) * 1999-05-27 2000-12-01 France Telecom CARRIER FREQUENCY REDUCING PASSET FILTER
WO2000074236A1 (en) * 1999-05-27 2000-12-07 France Telecom Band-pass filter with carrier frequency reduction
US7079823B1 (en) 1999-05-27 2006-07-18 Fahrenheit Thermoscope Llc Band-pass filter with carrier frequency reduction
US7555273B2 (en) 1999-05-27 2009-06-30 Fahrenheit Thermoscope Llc Bandpass filter with carrier frequency reduction
GB2380641A (en) * 2001-09-14 2003-04-09 Roke Manor Research common channel transceiver, which can reduce the noise from the transmitter antenna, appearing on the receiver antenna by using a digital filtering stage
GB2380641B (en) * 2001-09-14 2004-03-24 Roke Manor Research Transceiver

Also Published As

Publication number Publication date
FR2460069A1 (en) 1981-01-16
BR8003834A (en) 1981-01-13
DE3023773A1 (en) 1981-01-15
IT8022867A0 (en) 1980-06-18
JPS568944A (en) 1981-01-29
NL8003663A (en) 1980-12-30
IL60172A0 (en) 1980-07-31
IT1131352B (en) 1986-06-18
DK275980A (en) 1980-12-28

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Legal Events

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)