CN101577560B - Receiver and method for receiving frequency modulating signal - Google Patents
Receiver and method for receiving frequency modulating signal Download PDFInfo
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- CN101577560B CN101577560B CN 200810095900 CN200810095900A CN101577560B CN 101577560 B CN101577560 B CN 101577560B CN 200810095900 CN200810095900 CN 200810095900 CN 200810095900 A CN200810095900 A CN 200810095900A CN 101577560 B CN101577560 B CN 101577560B
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Abstract
The invention relates to a receiver for receiving a frequency modulating signal, which comprises an antenna, a modulator, an analog-to-digital converter, a demodulating module and a frequency shift estimating module. The antenna is used for receiving a frequency modulating signal; the modulator is coupled to the antenna and is used for converting the frequency modulating signal into an intermediate frequency signal; the analog-to-digital converter is coupled to the modulator and is used for converting the intermediate frequency signal into a digital intermediate frequency signal; the demodulating module is coupled to the analog-to-digital converter and is used for demodulating the digital intermediate frequency signal into an audio signal on the basis of a frequency shift compensating signal; and the frequency shift estimating module is coupled to the demodulating module and is used for generating the frequency shift compensating signal according to the audio signal.
Description
Technical field
The relevant a kind of frequency modulating signal receiver of the present invention and method of reseptance, and particularly relevant a kind of frequency modulating signal receiver and method of reseptance that can compensating frequency deviation.
Background technology
Frequency modulating (frequency modulation) technology is in the communication system that widely is applied to now.Conveyer carries out frequency modulating and obtains a frequency modulating signal according to the data that a specific wireless communication standard send institute's tendency to develop, and this frequency modulating signal is a radiofrequency signal.Receiver receive frequency modulating signal, and the frequency modulating signal is carried out demodulation obtain the data that institute's tendency to develop is given with reduction.
Please refer to Fig. 1, it is the calcspar of legacy frequencies modulating signal receiver.Frequency modulating signal receiver 100 comprises an antenna 110, a tuner 120, an analog-digital converter 130, a demodulating unit 140 and a compensating unit 150.Antenna 110 receive frequency modulating signal FM.Tuner 120 comprises a low noise amplifier 122, a local oscillator 124, a mixer 126 and an intermediate frequency amplifier 128.Low noise amplifier 122 is in order to amplification frequency modulating signal FM.Local oscillator 124 is in order to provide a local oscillating frequency LO.Frequency modulating signal FM frequency reducing after mixer 126 will amplify according to local oscillating frequency LO is one first intermediate-freuqncy signal IF1.Intermediate frequency amplifier is enlarged into one second intermediate-freuqncy signal IF2 with the first intermediate-freuqncy signal IF1.
Analog-digital converter 130 is converted to a digital medium-frequency signal DIF with the second intermediate-freuqncy signal IF2.140 couples of digital medium-frequency signal DIF of demodulating unit carry out demodulation to obtain audio signal AS.Yet, when the local oscillating frequency LO of the local oscillating frequency of conveyer end and frequency modulating signal receiver 100 has Light Difference, can cause audio signal AS to produce distortion (distortion), so that audio signal AS can have direct current offset level (DCoffset level), can cause thus the generation of system's degradation (degrade) phenomenon.
In order to overcome unwanted direct current offset level, compensating unit 150 detects among the audio signal AS because carrier frequency and the inconsistent direct current offset level that causes of local oscillating frequency LO, and produces according to this a control signal CS.Compensating unit 150 utilizes control signal CS to adjust the local oscillating frequency LO that local oscillator 124 produces, to eliminate the direct current offset level of audio signal AS.Yet above-mentioned method in order to the direct current offset level of eliminating audio signal AS is the analog end that is applied to frequency modulating signal receiver 100.For multiple Application Specific Integrated Circuit (ASIC) now, be better selection if frequency modulating signal receiver 100 can compensate audio signal AS in digital end.
Summary of the invention
The present invention provides a kind of frequency modulating signal receiver and method of reseptance, is that the digital end in the frequency modulating signal receiver compensates audio signal, to eliminate the direct current offset level that causes because of frequency shift (FS) in the audio signal.
According to a first aspect of the invention, propose a kind of frequency modulating signal receiver, comprise an antenna, a tuner, an analog-digital converter, a demodulation module and a frequency deviation estimation module.Antenna is in order to the receive frequency modulating signal.Tuner is coupled to antenna, in order to the frequency modulating signal is transformed to an intermediate-freuqncy signal.Analog-digital converter is coupled to tuner, in order to intermediate-freuqncy signal is converted to a digital medium-frequency signal.Demodulation module is coupled to analog-digital converter, in order to based on a frequency offset compensation signal digital medium-frequency signal is demodulated into an audio signal.The frequency deviation estimation module is coupled to demodulation module, produces the frequency offset compensation signal in order to the foundation audio signal.
According to a second aspect of the invention, propose a kind of frequency modulating signal acceptance method, comprise the following steps.The receive frequency modulating signal, and the frequency modulating signal is transformed to an intermediate-freuqncy signal.Intermediate-freuqncy signal is converted to a digital medium-frequency signal.Based on a frequency offset compensation signal digital medium-frequency signal is demodulated into an audio signal.Wherein, the frequency offset compensation signal is to produce according to audio signal.
Description of drawings
For foregoing of the present invention can be become apparent, the below will cooperate accompanying drawing that preferred embodiment of the present invention is elaborated, wherein:
Fig. 1 is the calcspar of legacy frequencies modulating signal receiver.
Fig. 2 is the calcspar according to the frequency modulating signal receiver of preferred embodiment of the present invention.
Fig. 3 is the calcspar according to the frequency deviation estimation module of preferred embodiment of the present invention.
Fig. 4 is the flow chart according to the frequency modulating signal acceptance method of preferred embodiment of the present invention.
Embodiment
The present invention proposes a kind of frequency modulating signal receiver and method of reseptance, the direct current offset level (DC offset level) that causes because of frequency shift (FS) in the audio signal (audio signal) is estimated (estimation), and in the digital end of frequency modulating signal receiver audio signal is compensated, the direct current offset level that produces because of distortion to eliminate audio signal, and and then eliminate the frequency shift (FS) of audio signal.
Please refer to Fig. 2, it is the calcspar according to the frequency modulating signal receiver of preferred embodiment of the present invention.Frequency modulating signal receiver 200 comprises an antenna 210, a tuner 220, an analog-digital converter 230, a demodulation module 240 and a frequency deviation estimation module 250.Antenna 210 is in order to receive a frequency modulating signal FM.This frequency modulating signal FM includes navigation information (pilot information), for example in order to indicate the navigation data of speech pattern (sound mode).Tuner 220 is coupled to antenna 210, and in order to frequency modulating signal FM is transformed to an intermediate-freuqncy signal IF, this intermediate-freuqncy signal IF for example is a sound (sound) intermediate-freuqncy signal.Analog-digital converter 230 is coupled to tuner 220, in order to intermediate-freuqncy signal IF is converted to a digital medium-frequency signal DIF.
The distortion of audio signal AS namely represents navigation information and may lose, may produce problems thus, the frequency modulating signal FM that for example receives for frequency modulating signal receiver 200 is stereo (stereo) signal, but demodulation module 240 resulting audio signal AS are single-tone (mono) signal.Therefore, frequency deviation estimation module 250 is coupled to demodulation module 240, and the direct current offset level that has in order to foundation audio signal AS is to produce frequency offset compensation signal DOCS.
DC digital frequency synthesizer 242 eliminating the carrier shift of frequency modulating signal FM, and is transformed to a numeral at phase (in-phase) fundamental frequency signal I and a digital quadrature (quadrature) fundamental frequency signal Q with digital medium-frequency signal DIF based on frequency offset compensation signal DOCS.The first low pass filter 244 is coupled to DC digital frequency synthesizer 242, in order to numeral is carried out filtering at phase fundamental frequency signal I.The second low pass filter 246 is coupled to DC digital frequency synthesizer 242, in order to digital quadrature baseband signal Q is carried out filtering.Demodulator 248 is coupled to the first low pass filter 244 and the second low pass filter 246, in order to the filtered numeral of demodulation at phase fundamental frequency signal I and filtered digital quadrature fundamental frequency signal Q, to obtain audio signal AS.
Please refer to Fig. 3, it is the calcspar according to the frequency deviation estimation module of preferred embodiment of the present invention.Frequency deviation estimation module 250 comprises a direct current deviation estimation unit 252 and frequency offset compensation estimation unit 254.Direct current offset level estimation unit 252 can be considered in fact a low pass filter, for example is a loop filter (loop filter), in order to audio signal AS is carried out filtering, with the high frequency composition among the filtered audio signal AS.Thus, direct current offset estimation unit 252 can obtain the direct current offset level of audio signal AS, and this direct current offset level is the carrier shift that corresponds to modulating signal FM, for example is 0.5 volt.Frequency offset compensation estimation unit 254 is coupled to direct current offset estimation unit 252, and anti-phase in order to the direct current offset level of foundation audio signal AS for example be-0.5 volt, converts compensating frequency to, with generation frequency offset compensation signal DOCS again.DC digital frequency synthesizer 242 namely can be eliminated the carrier shift of frequency modulating signal FM based on frequency offset compensation signal DOCS.
Please refer to Fig. 4, it is the flow chart according to the frequency modulating signal acceptance method of preferred embodiment of the present invention.At first, in step S400, receive a frequency modulating signal, and the frequency modulating signal is transformed to an intermediate-freuqncy signal.Then, in step S410, intermediate-freuqncy signal is converted to a digital medium-frequency signal.Then, in step S420, based on a frequency offset compensation signal digital medium-frequency signal is demodulated into an audio signal.Simultaneously, in step S430, audio signal is carried out filtering to obtain the direct current offset level of audio signal.Afterwards, in step S440, according to the anti-phase generation frequency offset compensation signal of the direct current offset level of audio signal.Above-mentioned frequency modulating signal acceptance method, its detailed principle is to be described in the frequency modulating signal receiver 200, therefore no longer repeat in this.
The disclosed frequency modulating signal receiver of the above embodiment of the present invention and method of reseptance, that leading of having of audio signal estimated because of the direct current offset level in frequency shift (FS), and utilize DC digital frequency synthesizer in the frequency modulating signal receiver, anti-phase based on the direct current offset level of being estimated, convert again compensating frequency to and to produce the frequency offset compensation signal audio signal is compensated, to eliminate the carrier shift of frequency modulating signal.Thus, can audio signal be compensated in the digital end of frequency modulating signal receiver.Therefore frequency modulating signal receiver of the present invention and method of reseptance more are applicable to popular now Application Specific Integrated Circuit (ASIC) compared to tradition, and the carrier shift of the frequency modulating signal of eliminating more can reach 150KHz.
In sum, although the present invention with preferred embodiment exposure as above, yet it is not to limit the present invention.The persond having ordinary knowledge in the technical field of the present invention, without departing from the spirit and scope of the present invention, when making the various changes that are equal to or replacement.Therefore, protection scope of the present invention is when looking accompanying being as the criterion that the application's claim defines.
Claims (5)
1. frequency modulating signal receiver comprises:
One antenna is in order to receive this frequency modulating signal;
One tuner is coupled to this antenna, in order to this frequency modulating signal is transformed to an intermediate-freuqncy signal;
One analog-digital converter is coupled to this tuner, in order to this intermediate-freuqncy signal is converted to a digital medium-frequency signal;
One demodulation module is coupled to this analog-digital converter, in order to based on a frequency offset compensation signal this digital medium-frequency signal is demodulated into an audio signal; And
One frequency deviation estimation module is coupled to this demodulation module, and in order to produce this frequency offset compensation signal according to this audio signal, this frequency deviation estimation module comprises:
One direct current deviation estimation unit is in order to obtain the direct current offset level of this audio signal; And
One frequency offset compensation estimation unit is coupled to this direct current offset estimation unit, in order to this frequency offset compensation signal of anti-phase generation according to the direct current offset level of this audio signal;
Wherein, this demodulation module comprises:
One DC digital frequency synthesizer is coupled to this analog-digital converter, in order to based on this frequency offset compensation signal this digital medium-frequency signal is transformed to a numeral at phase (in-phase) fundamental frequency signal and a digital quadrature fundamental frequency signal;
One first low pass filter is coupled to this DC digital frequency synthesizer, in order to this numeral is carried out filtering at the phase fundamental frequency signal;
One second low pass filter is coupled to this DC digital frequency synthesizer, in order to this digital quadrature fundamental frequency signal is carried out filtering; And
One demodulator is coupled to the first low pass filter and the second low pass filter, in order to demodulation filtered should numeral at phase fundamental frequency signal and filtered this digital quadrature fundamental frequency signal, to obtain this audio signal.
2. frequency modulating signal receiver according to claim 1 is characterized in that this direct current offset estimation unit is a low pass filter, in order to this audio signal is carried out filtering to obtain the direct current offset level of this audio signal.
3. frequency modulating signal receiver according to claim 1 is characterized in that this intermediate-freuqncy signal is a sound if signal.
4. frequency modulating signal acceptance method comprises:
A. receive this frequency modulating signal, and this frequency modulating signal is transformed to an intermediate-freuqncy signal;
B. this intermediate-freuqncy signal is converted to a digital medium-frequency signal; And
C. based on a frequency offset compensation signal this digital medium-frequency signal is demodulated into an audio signal;
D. this audio signal is carried out filtering to obtain the direct current offset level of this audio signal; And
E. according to this frequency offset compensation signal of anti-phase generation of the direct current offset level of this audio signal;
Wherein, this frequency offset compensation signal is to produce according to this audio signal;
Wherein, this step c comprises:
C1. based on this frequency offset compensation signal this digital medium-frequency signal is transformed to a numeral at phase fundamental frequency signal and a digital quadrature fundamental frequency signal;
C2. this numeral is carried out filtering at phase fundamental frequency signal and this digital quadrature fundamental frequency signal; And
C3. demodulation filtered should numeral at phase fundamental frequency signal and filtered this digital quadrature fundamental frequency signal, to obtain this audio signal.
5. frequency modulating signal acceptance method according to claim 4 is characterized in that this intermediate-freuqncy signal is a sound if signal.
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| CN 200810095900 CN101577560B (en) | 2008-05-08 | 2008-05-08 | Receiver and method for receiving frequency modulating signal |
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| CN 200810095900 CN101577560B (en) | 2008-05-08 | 2008-05-08 | Receiver and method for receiving frequency modulating signal |
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| CN101577560A CN101577560A (en) | 2009-11-11 |
| CN101577560B true CN101577560B (en) | 2013-04-24 |
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