GB2314981A - Radio receiver arrangements - Google Patents

Radio receiver arrangements Download PDF

Info

Publication number
GB2314981A
GB2314981A GB9713307A GB9713307A GB2314981A GB 2314981 A GB2314981 A GB 2314981A GB 9713307 A GB9713307 A GB 9713307A GB 9713307 A GB9713307 A GB 9713307A GB 2314981 A GB2314981 A GB 2314981A
Authority
GB
United Kingdom
Prior art keywords
phase
frequency
signals
local oscillator
signal
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Withdrawn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
GB9713307A
Other versions
GB9713307D0 (en
Inventor
Nicholas Paul Cowley
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 Semiconductors Ltd
Original Assignee
Plessey Semiconductors 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
Priority to GBGB9613812.8A priority Critical patent/GB9613812D0/en
Application filed by Plessey Semiconductors Ltd filed Critical Plessey Semiconductors Ltd
Priority to GB9713307A priority patent/GB2314981A/en
Publication of GB9713307D0 publication Critical patent/GB9713307D0/en
Publication of GB2314981A publication Critical patent/GB2314981A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/18Phase-modulated carrier systems, i.e. using phase-shift keying includes continuous phase systems
    • H04L27/22Demodulator circuits; Receiver circuits
    • H04L27/227Demodulator circuits; Receiver circuits using coherent demodulation
    • H04L27/2271Demodulator circuits; Receiver circuits using coherent demodulation wherein the carrier recovery circuit uses only the demodulated signals
    • H04L27/2273Demodulator circuits; Receiver circuits using coherent demodulation wherein the carrier recovery circuit uses only the demodulated signals associated with quadrature demodulation, e.g. Costas loop
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/32Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/38Demodulator circuits; Receiver circuits
    • H04L27/3818Demodulator circuits; Receiver circuits using coherent demodulation, i.e. using one or more nominally phase synchronous carriers
    • H04L27/3827Demodulator circuits; Receiver circuits using coherent demodulation, i.e. using one or more nominally phase synchronous carriers in which the carrier is recovered using only the demodulated baseband signals
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/0014Carrier regulation
    • H04L2027/0024Carrier regulation at the receiver end
    • H04L2027/0026Correction of carrier offset
    • H04L2027/003Correction of carrier offset at baseband only
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00Modulated-carrier systems
    • H04L27/0014Carrier regulation
    • H04L2027/0044Control loops for carrier regulation
    • H04L2027/0053Closed loops
    • H04L2027/0057Closed loops quadrature phase

Abstract

A quadrature phase shift keying (QPSK) transmission system amplifies a 480MHz intermediate frequency (IF) signal in an IF amplifier 1 and subsequently mixes it in two paths with quadrature 480 MHz signals from a local oscillator 4 using mixers 2, 3, by way of a phase splitter 5. Base-band signals in an in-phase (I) path and a quadrature-phase (Q) path from the outputs of the respective mixers 2 and 3 are applied to a dual analogue-to-digital convertor arrangement 8 by way of respective amplifiers 6 and 7. From here, a processor 9 demodulates and error checks received data and generates a reference signal of a frequency controlled by a digitally implemented Costas loop 10 in dependence upon the digitised I and Q signals. The reference signal is at about 80MHz. The Costas loop 10 effectively multiplies the I and Q signals, and the error output of this multiplier is used to tune the reference signal frequency so as to reduce the error. The process also corrects for phase errors, so that the reference signal is aligned both in frequency and in phase. This reference frequency signal is then fed back to control the frequency of the local oscillator 4 by means of a secondary phase locked loop 11.

Description

Radio Receiver Arrangements The present invention relates to radio receiver arrangements, and in particular although not exclusively to radio receiver arrangements for transmission systems utilising phase-shift modulation, such as quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM) systems.

Digital phase-shift modulation techniques are increasingly being used in both satellite and terrestrial transmission systems, with the phase-shift information being recovered at a receiver from intermediate frequency (F) signals, after one or more down-changes in frequency, for example in a quadrature-phase demodulator arrangement. In such a demodulator arrangement the IF signals are mixed with local oscillator signals in in-phase and quadrature phase paths, and from the analogue signals in these paths the digital information represented by the receivedcarrier modulation is extracted, for example by converting these analogue signals to digital form in an A to D convertor and utilising a digital signal processor to recover the information.

For correct operation of the receiver the local oscillator must be accurately aligned in frequency and phase with the IF frequency. This frequency and phase alignment may be achieved for example by the use of a feedback signal derived from a digitally-implemented Costas loop in the digital signal processor to control the frequency of the local oscillator. Alternatively an approximately aligned fixedfrequency local oscillator may be used in conjunction with a digitally-implemented de-rotation arrangement in the digital signal processor. In this second case the de-rotation achievable is typically 0.1 to 0.15 times the symbol rate, such that for a symbol rate of 1MHz the fixed-frequency local oscillator can be as much as 150 kHz in error.

It is necessary in both cases that low local oscillator phase noise be achieved, to minimise the demodulated bit error rate. In the first case this is achieved by the design of the voltage controlled oscillator. In the second case the fixed frequency itself may be defined by a high-Q resonator to minimise its contribution to the phase noise.

Also, the voltage-controlled oscillator arrangement is susceptible to supply line noise, microphony effects and radiative noise pick-up, all of which can contribute to degradation of the bit error rate.

In the case of fixed-frequency local oscillators the high-Q resonator and the additional de-rotation processing can add to the overall system cost, and it is difficult to achieve the required frequency alignment for low data rates. As there is no feedback system such oscillators can be particularly susceptible to supply line noise.

According to one aspect of the present invention in a radio receiver arrangement for a system in which carrier signals for transmission are phase-shift modulated with information in digitised form, in which receiver arrangement received signals are mixed with local oscillator signals in in-phase and quadrature paths and analogue signals in these paths are applied by way of analogue-to-digital conversion means to a data signal processing means for demodulation, said data signal processing means is arranged to derive from the analogue-to-digitally converted signals a reference frequency signal phase-locked to said analogue signals, and a phase-locked loop circuit is provided to control the frequency of said local oscillator in dependence upon the frequency of said reference frequency signal.

According to another aspect of the present invention a radio receiver arrangement for demodulating phase-shift modulated carrier signals comprises means to mix the carrier signals with local oscillator signals in in-phase and quadrature-phase paths, analogue to digital convertor means coupling said in-phase and quadrature-phase paths to digital signal processor means arranged to generate a reference frequency signal from signals in said in-phase and quadrature-phase paths, and a phase-locked loop circuit arrangement for controlling the frequency of said local oscillator signals in dependence upon the frequency of said reference frequency signal.

Preferably the reference frequency signal is generated by means of a digitally implemented Costas loop.

Preferably the local oscillator signals are in the order of six times the frequency of the reference signal and, more preferably, the local oscillator signal frequency is of the order of 480MHz and the reference frequency is of the order of 80MHz. This allows the use of a large bandwidth phase locked loop which can offer improvements since the oscillator can have poor phase noise performance, the phase locked loop then being relied on to clean up the close-in phase noise. A large bandwidth phase locked loop also suppresses microphony and allows for fast settling time and a fully symbol rate flexible system.

A radio receiver arrangement in accordance with the present invention will now be described by way of example with reference to the accompanying drawing, which shows part of the receiver arrangement schematically.

Referring to the drawing in a radio receiver arrangement for a quadrature phase shift keying (QPSK) transmission system intermediate frequency signals at around 480 MHz, after one or more frequency changing stages (not shown), are applied at the output of an IF amplifier 1 to a pair of mixers 2 and 3, to which local oscillator signals at 480 MHz are also applied, in phase-quadrature, from a local oscillator 4 by way of a phase splitter 5. Base-band signals in an in-phase (I) path and a quadrature-phase (Q) path from the outputs of the respective mixers 2 and 3 are applied to a dual analogue-to-digital convertor arrangement 8 by way of respective amplifiers 6 and 7.

Digitised output signals from the convertor arrangement 8 are applied to a digital signal processor 9, which is arranged to perform demodulation of the QPSK signals together with forward error correction. The processor 9 also generates a reference signal of a frequency controlled by a digitally implemented Costas loop 10 in dependence upon the digitised I and Q signals. The Costas loop 10 effectively multiplies the I and Q signals, and the error output of this multiplier is used to tune the reference signal frequency so as to reduce the error. The process also corrects for phase errors, so that the reference signal is aligned both in frequency and in phase.

This reference frequency signal is then fed back to control the frequency of the local oscillator 4 by means of a secondary phase locked loop 11.

The processor 9 is able to generate a very low phase-noise reference signal, of a frequency of approximately 80MHz, which is optimally aligned with the incoming I and Q signals, and this signal is then multiplied in frequency by the phase locked loop 11. Since the bandwidth of this loop can be large the oscillator 4 can have poor phase noise performance, the phase locked loop then being relied on to clean up the close-in phase noise..

The use of an onchip reference signal source reduces cost and is less prone to microphony, while the large bandwidth of the loop 11 allows for fast settling time and a fully symbol rate flexible system, and also suppresses microphony.

Since the reference signal is at 80HMz it can easily be made immune to direct radiative coupling interference from noise such as video-type noise.

Claims (7)

1. A radio receiver arrangement for a system in which carrier signals for transmission are phase-shift modulated with information in digitised form, in which receiver arrangement received signals are mixed with local oscillator signals in inphase and quadrature paths and analogue signals in these paths are applied by way of analogue-to-digital conversion means to a data signal processing means for demodulation, wherein said data signal processing means is arranged to derive from the analogue-to-digitally converted signals a reference frequency signal phaselocked to said analogue signals, and a phase-locked loop circuit is provided to control the frequency of said local oscillator in dependence upon the frequency of said reference frequency signal.
2. A radio receiver arrangement for demodulating phase-shift modulated carrier signals comprising means to mix the carrier signals with local oscillator signals in in-phase and quadrature-phase paths, analogue to digital converter means coupling said in-phase and quadrature-phase paths to digital signal processor means arranged to generate a reference frequency signal from signals in said in-phase and quadrature-phase paths, and a phase-locked loop circuit arrangement for controlling the frequency of said local oscillator signals in dependence upon the frequency of said reference frequency signal.
3. A radio receiver arrangement in accordance with Claim 2 wherein the reference frequency signal is generated by means of a digitally implemented Costas loop.
4. A radio receiver arrangement in accordance with Claim 2 or Claim 3 wherein the frequency of the reference frequency signal is substantially a sub-multiple of the frequency of the local oscillator signals.
5. A radio receiver arrangement in accordance with Claim 4 wherein the local oscillator signals are in the order of six times the frequency of the reference signal.
6. A radio receiver arrangement in accordance with Claim 5 in wherein the local oscillator signal frequency is of the order of 480MHz and the reference frequency is of the order of 80MHz.
7. A radio receiver arrangement substantially as hereinbefore described with reference to the accompanying drawing.
GB9713307A 1996-07-02 1997-06-25 Radio receiver arrangements Withdrawn GB2314981A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GBGB9613812.8A GB9613812D0 (en) 1996-07-02 1996-07-02 Radio receiver arrangements
GB9713307A GB2314981A (en) 1996-07-02 1997-06-25 Radio receiver arrangements

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9713307A GB2314981A (en) 1996-07-02 1997-06-25 Radio receiver arrangements

Publications (2)

Publication Number Publication Date
GB9713307D0 GB9713307D0 (en) 1997-08-27
GB2314981A true GB2314981A (en) 1998-01-14

Family

ID=26309612

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9713307A Withdrawn GB2314981A (en) 1996-07-02 1997-06-25 Radio receiver arrangements

Country Status (1)

Country Link
GB (1) GB2314981A (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2378590A (en) * 2001-06-19 2003-02-12 Nec Corp AFC circuit
GB2379105A (en) * 2001-08-24 2003-02-26 Roke Manor Research Improvements in or relating to fast frequency-hopping modulators and demodulators
WO2007080141A1 (en) * 2006-01-11 2007-07-19 International Business Machines Corporation Signal phase control in an integrated radio circuit
CN100345391C (en) * 2003-08-19 2007-10-24 索尼株式会社 Frequency channel characteristics evaluation system and method, communication apparatus and method
GB2461921A (en) * 2008-07-18 2010-01-20 Phasor Solutions Ltd Phased array antenna element with a phase corrected oscillator
US9628125B2 (en) 2012-08-24 2017-04-18 Phasor Solutions Limited Processing a noisy analogue signal
US20170134155A1 (en) * 2015-11-11 2017-05-11 Taiwan Semiconductor Manufacturing Co., Ltd. Carrier synchronization device
US9917714B2 (en) 2014-02-27 2018-03-13 Phasor Solutions Limited Apparatus comprising an antenna array

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2253751A (en) * 1990-07-30 1992-09-16 Motorola Inc Dual mode automatic frequency control
US5325401A (en) * 1992-03-13 1994-06-28 Comstream Corporation L-band tuner with quadrature downconverter for PSK data applications
US5528633A (en) * 1992-03-13 1996-06-18 Comstream Corporation Tuner with quadrature downconverter for pulse amplitude modulated data applications

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2253751A (en) * 1990-07-30 1992-09-16 Motorola Inc Dual mode automatic frequency control
US5325401A (en) * 1992-03-13 1994-06-28 Comstream Corporation L-band tuner with quadrature downconverter for PSK data applications
US5528633A (en) * 1992-03-13 1996-06-18 Comstream Corporation Tuner with quadrature downconverter for pulse amplitude modulated data applications

Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2378590A (en) * 2001-06-19 2003-02-12 Nec Corp AFC circuit
US6853255B2 (en) 2001-06-19 2005-02-08 Nec Corporation AFC circuit compensating an error in oscillation frequency
GB2378590B (en) * 2001-06-19 2005-04-20 Nec Corp AFC circuit
GB2379105A (en) * 2001-08-24 2003-02-26 Roke Manor Research Improvements in or relating to fast frequency-hopping modulators and demodulators
GB2379106A (en) * 2001-08-24 2003-02-26 Roke Manor Research Improvements in or relating to fast frequency hopping demodulators
GB2379106B (en) * 2001-08-24 2003-07-09 Roke Manor Research Improvements in or relating to fast frequency-hopping demodulators
GB2379105B (en) * 2001-08-24 2003-07-09 Roke Manor Research Improvements relating to fast frequency-hopping modulators and demodulators
CN100345391C (en) * 2003-08-19 2007-10-24 索尼株式会社 Frequency channel characteristics evaluation system and method, communication apparatus and method
WO2007080141A1 (en) * 2006-01-11 2007-07-19 International Business Machines Corporation Signal phase control in an integrated radio circuit
US9253004B2 (en) 2006-01-11 2016-02-02 International Business Machines Corporation Apparatus and method for signal phase control in an integrated radio circuit
US9137070B2 (en) 2006-01-11 2015-09-15 International Business Machines Corporation Apparatus and method for signal phase control in an integrated radio circuit
US10008772B2 (en) 2008-07-18 2018-06-26 Phasor Solutions Limited Phased array antenna and a method of operating a phased array antenna
CN102113172A (en) * 2008-07-18 2011-06-29 相量解决方案有限公司 Phased array antenna and method of operating phased array antenna
GB2474923A (en) * 2008-07-18 2011-05-04 Phasor Solutions Ltd Phased array antenna element with a phase corrected oscillator
CN102113172B (en) * 2008-07-18 2014-12-24 相量解决方案有限公司 Phased array antenna and method of operating phased array antenna
GB2461921B (en) * 2008-07-18 2010-11-24 Phasor Solutions Ltd A phased array antenna and a method of operating a phased array antenna
GB2461921A (en) * 2008-07-18 2010-01-20 Phasor Solutions Ltd Phased array antenna element with a phase corrected oscillator
US9300040B2 (en) 2008-07-18 2016-03-29 Phasor Solutions Ltd. Phased array antenna and a method of operating a phased array antenna
GB2474923B (en) * 2008-07-18 2011-11-16 Phasor Solutions Ltd A phased array antenna and a method of operating a phased array antenna
US9628125B2 (en) 2012-08-24 2017-04-18 Phasor Solutions Limited Processing a noisy analogue signal
US10069526B2 (en) 2012-08-24 2018-09-04 Phasor Solutions Limited Processing a noisy analogue signal
US9917714B2 (en) 2014-02-27 2018-03-13 Phasor Solutions Limited Apparatus comprising an antenna array
US20170134155A1 (en) * 2015-11-11 2017-05-11 Taiwan Semiconductor Manufacturing Co., Ltd. Carrier synchronization device
CN106685875A (en) * 2015-11-11 2017-05-17 台湾积体电路制造股份有限公司 Carrier synchronization device
US10009167B2 (en) * 2015-11-11 2018-06-26 Taiwan Semiconductor Manufacturing Co., Ltd. Carrier synchronization device
TWI635739B (en) * 2015-11-11 2018-09-11 台灣積體電路製造股份有限公司 Carrier synchronization device and method
US10326584B2 (en) * 2015-11-11 2019-06-18 Taiwan Semiconductor Manufacturing Co., Ltd. Carrier synchronization device

Also Published As

Publication number Publication date
GB9713307D0 (en) 1997-08-27

Similar Documents

Publication Publication Date Title
US9253004B2 (en) Apparatus and method for signal phase control in an integrated radio circuit
CA2074974C (en) Demodulator for digitally modulated wave
US7564929B2 (en) System for coherent demodulation of binary phase shift keying signals (BPSK)
JP3647894B2 (en) Intermediate frequency FM receiver using analog oversampling to increase signal bandwidth
AU600638B2 (en) Carrier recovery circuit for offset qpsk demodulators
US5719527A (en) Method and apparatus for amplifying, modulating and demodulating
EP0799522B1 (en) Image-reject mixers
US4384357A (en) Self-synchronization circuit for a FFSK or MSK demodulator
CA2296855C (en) Receiving and demodulating a digital television signal
US5999793A (en) Satellite receiver tuner chip with frequency synthesizer having an externally configurable charge pump
US5535247A (en) Frequency modifier for a transmitter
US5438591A (en) Quadrature amplitude modulation type digital radio communication device and method for preventing abnormal synchronization in demodulation system
EP0645917B1 (en) Demodulator
US7881401B2 (en) Transmitter arrangement and signal processing method
JP3173788B2 (en) Digital transmission equipment and direct conversion receiver
KR960015838B1 (en) Receiver adaptively operable for multiple transmission system
US3993956A (en) Digital detection system for differential phase shift keyed signals
US5787123A (en) Receiver for orthogonal frequency division multiplexed signals
US9337965B2 (en) Systems and methods for asynchronous re-modulation with adaptive I/Q adjustment
KR970007618B1 (en) Afc circuit for qpsk demodulator
US4630283A (en) Fast acquisition burst mode spread spectrum communications system with pilot carrier
EP1479159B1 (en) Digital phase locked loop
US6192088B1 (en) Carrier recovery system
RU2115222C1 (en) Phase-angle corrector for power amplifier feedback circuit (options)
US7787630B2 (en) FM stereo decoder incorporating Costas loop pilot to stereo component phase correction

Legal Events

Date Code Title Description
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)