WO2010041211A1 - Procédé de verrouillage de fréquence pour la réception de signaux rds - Google Patents

Procédé de verrouillage de fréquence pour la réception de signaux rds Download PDF

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Publication number
WO2010041211A1
WO2010041211A1 PCT/IB2009/054419 IB2009054419W WO2010041211A1 WO 2010041211 A1 WO2010041211 A1 WO 2010041211A1 IB 2009054419 W IB2009054419 W IB 2009054419W WO 2010041211 A1 WO2010041211 A1 WO 2010041211A1
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WO
WIPO (PCT)
Prior art keywords
signal
symbol
phase
quadrature
shape
Prior art date
Application number
PCT/IB2009/054419
Other languages
English (en)
Inventor
Erik Keukens
Original Assignee
Nxp B.V.
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 Nxp B.V. filed Critical Nxp B.V.
Publication of WO2010041211A1 publication Critical patent/WO2010041211A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/22—Demodulator circuits; Receiver circuits
    • H04L27/227—Demodulator circuits; Receiver circuits using coherent demodulation
    • H04L27/2271—Demodulator circuits; Receiver circuits using coherent demodulation wherein the carrier recovery circuit uses only the demodulated signals
    • H04L27/2273—Demodulator circuits; Receiver circuits using coherent demodulation wherein the carrier recovery circuit uses only the demodulated signals associated with quadrature demodulation, e.g. Costas loop
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H40/00—Arrangements specially adapted for receiving broadcast information
    • H04H40/18—Arrangements characterised by circuits or components specially adapted for receiving
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/28—Arrangements for simultaneous broadcast of plural pieces of information
    • H04H20/33—Arrangements for simultaneous broadcast of plural pieces of information by plural channels
    • H04H20/34—Arrangements for simultaneous broadcast of plural pieces of information by plural channels using an out-of-band subcarrier signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H2201/00—Aspects of broadcast communication
    • H04H2201/10—Aspects of broadcast communication characterised by the type of broadcast system
    • H04H2201/13—Aspects of broadcast communication characterised by the type of broadcast system radio data system/radio broadcast data system [RDS/RBDS]

Definitions

  • the invention relates to a frequency locking method especially for reception of RDS data signals as claimed in claim 1.
  • FM (frequency modulation) signal receivers are widely used.
  • FM radio receiver are used to receive radio signals and additionally RDS (radio data system) and /or ARI (auto-radio-information) signals which contain additional information drivers of cars appreciate.
  • RDS radio data system
  • ARI auto-radio-information signals
  • AM amplitude modulation
  • the pilot can be used. Since the shape of the transmitted symbol is basically known, convo luting the incoming signal with the given symbol shape will result in maximum filtering to acquire the most reliable control signal for frequency and/or phase locking.
  • RDS demodulators typically use the RDS bandwidth to filter the control signal and an un-correlated carrier signal, e.g. a ARI signal, may take over the control of the frequency/phase locking.
  • a ARI signal is used since it is well known that the ARI signal shows a 90° phase shift with the RDS signal and an additionally installed ARI detector automatically uses the quadrature signal accordingly.
  • Radio Data System RDS
  • ARI Radio Data System
  • GB 2383481 A discloses an RDS decoder which includes a demodulator and a data decoder, wherein the demodulator is a synchronous demodulator which receives a multiplex signal in which an RDS signal is superimposed on an FM audio signal and generates a baseband RDS signal, wherein a decoder decodes the RDS baseband signal, while the demodulator includes a quadrature demodulator, a filter and a phase-locked loop.
  • EP 0714183 uses the known and expected symbol such that the data stream will be analysed with regard to occurrence of the expected symbol. Nevertheless the use of the ARI signal has several disadvantages. First of all the phase difference is not always 90°. Therefore this leads to failures. Additionally the presence of ARI is not reliable since many other effects may cause a carrier at the specific ARI frequency, e.g. the third harmonic of the 19 kHz pilot tone.
  • the object of the invention will be solved by a method according to the features of claim 1.
  • the inventive method of frequency locking for use in FM receivers where besides a FM signal an additional data stream will be transmitted and where the FM data and the additional data stream are divided in an in-phase signal and a quadrature signal is realised such that demodulation for signal reception takes place and wherein a symbol filter is used for the demodulation of the in-phase signal and for the demodulation of the quadrature signal.
  • the in-phase signal and the quadrature signal are multiplied to generate an error signal.
  • the control method forces all the information in either the in-phase signal or in the quadrature signal.
  • the amount of information transmitted can be demodulated by means of a symbol filter.
  • the symbol shape is at least almost constant and wherein the information is stored in the sign.
  • the shape of the symbol will be convoluted in the analogue domain or in the digital domain.
  • Fig. 1 shows a schematic diagram to explain the inventive method.
  • FIG. 1 shows schematically a diagram 1 in order to explain the inventive frequency locking method.
  • the diagram 1 shows two symbol filters 2, 3 and a multiplying stage 4 at the output of the filters 2, 3.
  • the Costas loop has the disadvantage that a carrier signal will also cause locking. Removing this carrier by a first order low-cut filter would result in a very slow locking algorithm.
  • the inventive frequency locking method proposes that bases its control method in forcing all the information and not only the strongest signal in either the in-phase signal 5 or in the quadrature signal 6, depending on the control parameters. This means that all the information is in one plane either in the in-phase plane or in the quadrature plane which is shifted about 90° compared to the in phase signal plane.
  • the amount of information can preferably be demodulated or generated by using a symbol filter 2, 3. Since the exact symbol shape is at least almost constant and the information as such is stored in the sign.
  • the block diagram 1 schematically shows the generation of an error signal 7 in the loop. As shown in fig. 1 both the in-phase signal 5 and the quadrature signal 6 are feed to one symbol filter 2, 3 each. After the treatment by the symbol filters 2, 3 and the multiplying stage 4 which multiplies the output of both filters 2, 3 an error signal 7 is generated.
  • each symbol filter 2, 3 indicates the similarity between the content and the shape of a symbol and the amount of information in that path accordingly. This means that the algorithm is not forcing just any signal to O' Hz but the RDS information is forced into one stream.
  • the shape of a symbol in the in-phase or in the quadrature path equals the shape of a sine wave. This means that two peaks can occur, one at the centre of a symbol and the other between two symbols. If twice the same symbol is transmitted two peaks will occur, one positive and one negative peak, when two different symbols are transmitted the value between the symbols will be zero or at least almost zero.
  • the shape of the symbol will be convoluted in the time domain.
  • This convolution is a more complicated operation in the analogue domain but it is a less complicated operation in the digital domain. Therefore implementation in the digital domain is proposed.
  • the method can be used in either a control loop or a feed forward system.
  • the system can be used for all systems where the symbol shape is known and the information is stored in the sign. Additionally the method might be used for a multi symbol shape systems too.
  • the generated indication for the reliability of the data in both paths can be used to control the frequency/phase locking in that case.
  • the inventive concept is applicable even in case the symbol filter shape does not match the symbol shape exactly. Therefore other weighted averages might be used too.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

Abstract

La présente invention a pour objet un procédé de verrouillage de fréquence destiné à être utilisé dans les récepteurs FM où, en plus d’un signal FM, un flux de données supplémentaires sera transmis, les données FM et le flux de données supplémentaires étant divisés en un signal en phase (5) et un signal de quadrature (6) de telle sorte qu’une démodulation pour la réception du signal se produise, et un filtre de symbole (2,3) étant utilisé pour le signal en phase (5) et pour le signal de quadrature (6).
PCT/IB2009/054419 2008-10-08 2009-10-08 Procédé de verrouillage de fréquence pour la réception de signaux rds WO2010041211A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP08105520 2008-10-08
EP08105520.4 2008-10-08

Publications (1)

Publication Number Publication Date
WO2010041211A1 true WO2010041211A1 (fr) 2010-04-15

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2009/054419 WO2010041211A1 (fr) 2008-10-08 2009-10-08 Procédé de verrouillage de fréquence pour la réception de signaux rds

Country Status (1)

Country Link
WO (1) WO2010041211A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0374996A1 (fr) * 1988-12-01 1990-06-27 Koninklijke Philips Electronics N.V. Récepteur FM
EP0471412A2 (fr) * 1990-08-15 1992-02-19 Koninklijke Philips Electronics N.V. Récepteurs pour transmissions en modulation de fréquence
GB2386483A (en) * 2001-12-17 2003-09-17 Mitsubishi Electric Corp RDS decoder
US20040247133A1 (en) * 2001-03-10 2004-12-09 Stefan Gierl Apparatus and method for demodulating a radio data system (RDS) signal

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0374996A1 (fr) * 1988-12-01 1990-06-27 Koninklijke Philips Electronics N.V. Récepteur FM
EP0471412A2 (fr) * 1990-08-15 1992-02-19 Koninklijke Philips Electronics N.V. Récepteurs pour transmissions en modulation de fréquence
US20040247133A1 (en) * 2001-03-10 2004-12-09 Stefan Gierl Apparatus and method for demodulating a radio data system (RDS) signal
GB2386483A (en) * 2001-12-17 2003-09-17 Mitsubishi Electric Corp RDS decoder

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
THADDEUS A. ROPPEL: "Chapter 16: THE COSTAS LOOP", vol. A2, 3 January 2002 (2002-01-03), pages 145 - 154, XP002561857, Retrieved from the Internet <URL:http://www.eng.auburn.edu/~troppel/courses/TIMS-manuals-r5/TIMS%20Experiment%20Manuals/Student_Text/Vol-A2/A2-16.pdf> [retrieved on 20091209] *

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