CN1265242A - Radio receiver - Google Patents
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- CN1265242A CN1265242A CN 98807586 CN98807586A CN1265242A CN 1265242 A CN1265242 A CN 1265242A CN 98807586 CN98807586 CN 98807586 CN 98807586 A CN98807586 A CN 98807586A CN 1265242 A CN1265242 A CN 1265242A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04H—BROADCAST COMMUNICATION
- H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
- H04H20/86—Arrangements characterised by the broadcast information itself
- H04H20/88—Stereophonic broadcast systems
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- 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
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/1646—Circuits adapted for the reception of stereophonic signals
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Abstract
A radio receiver having circuits formed integrally on a semiconductor substrate while decreasing the number of external components and reducing the component cost. The radio receiver (100) comprises an antenna (19), an FM tuner (1), an FM PLL circuit (2), an FM detector (3), an FM stereo demodulator (4), low frequency amplifiers (101, 102) and loudspeakers (103, 104) so as to receive FM broadcast. The radio receiver (100) also comprises an antenna (59), an AM tuner (5), an AM PLL circuit (6), an AM detector (7), a low frequency amplifier (105), and a loudspeaker (106) so as to receive AM broadcast. The FM PLL circuit (2) and the AM PLL circuit (6) each output a local oscillation signal based on a reference signal synchronized with a pilot signal outputted from the FM stereo demodulator (4).
Description
Invention field
The present invention relates to radio receiver, comprise electronic tuning type tuning circuit and FM stereo demodulation circuit.
Background of invention
Current commercially available radio receiver uses the superhet system mostly, is the centre frequency of band pass filter by the broadcasting frequency frequency conversion with needs, and does not change the centre frequency and the bandwidth characteristic of band pass filter, only selects broadcast singal.By in response to received signal and the local oscillation signal mixing of tuning indicator, carry out this frequency conversion with the high frequency amplification.If the local oscillation signal frequency is inaccurate, the signal frequency of frequency conversion can be from the carrier deviation of band pass filter.Here it is, and why local oscillation signal needs accurately and the reason of frequency fluctuation minimum.Recently, PLL frequency synthesis type electronic tuning circuit is used to produce local oscillation signal, because they are easily by system controlled by computer.In the oscillator of this electron-like tuning circuit, use quartz (controlled) oscillator usually, because its accuracy and low frequency fluctuation.
Many current commercially available radio receivers are designed to also receive the FM stereophonic signal except the AM signal.When receiving the FM stereophonic signal, the FM stereo composite signal obtains after the FM detection.This composite signal of stereo demodulation circuit demodulation is to obtain left audio signal (L signal) and right audio signal (R signal).
The execution of the demodulating process in the stereo demodulation circuit be for based on the synchronous strobe signal of pilot signal that is included in the stereo composite signal, extract or the sampling stereo composite signal in L and R signal.In order to realize stable demodulation performance, known stereo demodulation circuit adopts for example ceramic resonator.
The intrinsic characteristic of material of element is made in the quartz (controlled) oscillator and the ceramic resonator utilization that are used in electronic tuning circuit and the stereo demodulation circuit, so can not be integrated on the Semiconductor substrate.The result is, when integrated whole radio receiver circuit on Semiconductor substrate, they have increased the element of outside connection.
Because as mentioned above, local oscillation signal from PLL frequency synthesis type electronic tuning circuit needs high accuracy and low frequency fluctuation, so must carefully only select high-frequency accuracy quartz (controlled) oscillator, be used to produce local oscillation signal, thereby increased the element cost.
Of the present invention open
The present invention has considered the problems referred to above, and purpose provides a kind of radio receiver, is integrated on the Semiconductor substrate, has minimum outer connecting element number, and uses cheap element.
Radio receiver according to the present invention comprises: first oscillator, with the pilot signal synchronized oscillation that is included in the FM stereo composite signal; With second oscillator, based on oscillator signal from described first oscillator, the local oscillation signal that vibration needs with the frequency conversion that the FM received signal is provided.The result is, if produce the needed high precision of frequency conversion and the low frequency fluctuation local oscillation signal of FM received signal by phase-locked loop (PLL) circuit, the needed signal of the demodulation process of FM stereo composite signal is produced synchronously by first oscillator and pilot signal, from the oscillator signal of first oscillator output by frequency division, be used as the reference frequency signal of aforementioned PLL circuit, thereby no longer need the oscillator of special generation reference frequency signal.Particularly, when the circuit of integrated radio receiver on Semiconductor substrate, can reduce the element that the outside of using such as quartz (controlled) oscillator etc. connects in oscillator.
If aforesaid first oscillator uses quartz (controlled) oscillator to constitute by a PLL circuit with the form of voltage controlled oscillator, strobe signal can only produce with pilot signal exactly synchronously, thereby realized stereosonic demodulation process, and do not had the influence of noise etc.Oscillator signal from this first oscillator is a pin-point accuracy, has minimum frequency fluctuation, thereby makes it possible to be used as reference frequency signal, by the oscillator signal generation local oscillation signal of frequency division from first oscillator.Because from the oscillator signal of first oscillator output and pilot signal Be Controlled synchronously, unnecessary careful the selection has the quartz (controlled) oscillator of high-frequency accuracy, thereby makes it possible to use cheap quartz (controlled) oscillator and reduction element cost.
If the 2nd PLL circuit comprises first frequency divider and aforementioned second oscillator with variable division ratio, be used as the reference frequency signal of the 2nd PLL circuit from the oscillator signal of the frequency division of first oscillator, can synchronously produce the local oscillation signal of high accuracy and minimum frequency fluctuation with the pilot signal that is included in the FM stereo composite signal at an easy rate by second oscillator.By changing the frequency dividing ratio of first frequency divider, the frequency of FM received signal can be changed the frequency into any hope.
Especially, preferably according to the pilot signal frequency with set the frequency of oscillation of first oscillator from the local oscillation signal frequency of second oscillator.Specifically, the frequency of oscillation of first oscillator is set, make to equal the pilot signal frequency by the oscillation signal frequency of the frequency dividing ratio frequency division of first frequency divider, equal at interval by the outputting oscillation signal frequency of the frequency dividing ratio frequency division of second frequency divider by the Frequency Distribution of the FM broadcasting of a predetermined integers frequency division from described first oscillator from described first oscillator.Perhaps, the frequency of oscillation of first oscillator is set to the integral multiple of the Frequency Distribution least common multiple at interval of pilot signal frequency and FM broadcasting.The appropriate setting of the frequency of oscillation of first oscillator like this make can frequency division first oscillator output, be used to provide reference frequency signal, based on this reference frequency signal, second oscillator provides the frequency conversion of FM received signal necessary local oscillation signal.
Although above-mentioned radio receiver purpose is only to receive the FM broadcast singal, also may both receive the FM broadcast singal, also receive the AM broadcast singal.In this FM/AM radio receiver, adopted the 3rd oscillator in addition, with based on outputting oscillation signal, provide the local oscillation signal of the frequency conversion needs of AM received signal from first oscillator.For this purpose, be similar to and only receive the FM broadcast singal, by frequency division,, thereby no longer need to be used to produce the special oscillator of the reference frequency signal of AM broadcasting from the oscillator signal of first oscillator as reference frequency signal, reduced the number of element.
The 3rd PLL circuit can comprise second frequency divider and aforementioned the 3rd oscillator with variable division ratio.Can be used as the reference frequency signal of the 3rd PLL circuit from the oscillator signal of the frequency division of first oscillator, thereby synchronously produce the local oscillation signal of the AM broadcasting of high accuracy and minimum frequency fluctuation with the pilot signal that is included in the FM stereo composite signal at an easy rate by the 3rd oscillator.By changing the frequency dividing ratio of second frequency divider, AM received signal frequency can be controlled as the value of any hope.
Especially,, also receive the AM broadcast singal, preferably by the pilot signal frequency with set the frequency of oscillation of first oscillator from the local oscillation signal frequency of the second and the 3rd oscillator if a radio receiver can both receive the FM broadcast singal.Specifically, the frequency of oscillation of first oscillator is set, make and to equal the pilot signal frequency by the outputting oscillation signal frequency of the first frequency dividing ratio frequency division from first oscillator, equal at interval by the outputting oscillation signal frequency of the second frequency dividing ratio frequency division from described first oscillator, equal at interval by the outputting oscillation signal frequency of tri-frequency divider frequency division by the Frequency Distribution of the AM broadcasting of a predetermined integers frequency division from described first oscillator by the Frequency Distribution of the FM broadcasting of a predetermined integers frequency division.Perhaps, the frequency of oscillation of first oscillator is set to the integral multiple of the Frequency Distribution interval of pilot signal frequency, FM broadcasting and the Frequency Distribution least common multiple at interval that AM broadcasts.The setting of the frequency of oscillation of first oscillator like this make can frequency division first oscillator output, as the reference frequency signal of the second and the 3rd PLL circuit.The local oscillation signal that the frequency conversion of FM and AM received signal needs can be derived from the second and the 3rd oscillator respectively based on reference frequency signal.
Brief description of drawings
Fig. 1 is the block diagram that the total of radio receiver according to an embodiment of the invention is shown;
Fig. 2 is the more detailed block diagram of the FM stereo demodulation circuit of Fig. 1;
Fig. 3 illustrates the signal waveform of the operation of the stereo separation circuit that is used to describe Fig. 2; With
Fig. 4 is the more detailed block diagram of FM PLL circuit.
The preferred embodiments of the present invention
Radio receiver according to the present invention by with the synchronous oscillating operation of pilot signal that is included in the FM stereo composite signal, produce stereo demodulation and handle required strobe signal.Based on the oscillator signal of deriving, produce the reference frequency signal that the PLL circuit needs, so that local oscillation signal to be provided by oscillating operation.Now, a embodiment according to radio receiver of the present invention is described with reference to the drawings.
(1) total of radio receiver
Fig. 1 shows the total of the one embodiment of the present of invention that can receive FM and AM signal.Radio receiver 100 shown in Figure 1 comprises: FM tuner pack 1 as front end, is used to receive the frequency conversion of FM signal and the FM signal that is used for receiving by antenna 19; FM PLL circuit 2 is used to produce local oscillation signal, is used for the frequency conversion of FM tuner pack 1; FM detecting circuit 3 is used at the output detection FM stereo composite signal from FM tuner pack 1; FM stereo demodulation circuit 4 is used for from FM stereo composite signal demodulation L and R signal; Low-frequency amplifier circuit 101,102 is used for amplifying respectively L and R signal; With loud speaker 103,104, be used to provide audio frequency output.
In addition, radio receiver 100 comprises AM tuner pack 5, as front end, is used to receive the frequency conversion of AM signal and the AM signal that is used for receiving by antenna 59; AM PLL circuit 6 is used to produce local oscillation signal, is used for the frequency conversion of AM tuner pack 5; AM detecting circuit 7 is used in the output detection AM audio signal from AM tuner pack 5; Low frequency amplifier 105 is used to amplify the AM audio signal; With loud speaker 106, be used to provide audio frequency output.
In radio receiver 100, also comprise: three frequency dividers 22,23,24; Tuning control section 9 and operation part 10, be used for being provided for FM PLL circuit 2 and AM PLL circuit 6 the PLL operation reference frequency signal and be used to import tuning instruction.
(2) operation of radio receiver
In the radio receiver 100 of said structure, the operation that is used to receive FM and AM signal will be described respectively.At first, the operation that receives the FM signal is described.
The FM signal that receives by antenna 19 is middle FM signal by 1 frequency conversion of FM tuner pack.As shown in Figure 1, FM tuner pack 1 comprises high frequency (HF) amplifying circuit 11, mixting circuit 13, band pass filter 15 and intermediate frequency (IF) amplifying circuit 17.HF amplifying circuit 11 amplifies the FM signal that receives by antenna 19.Mixting circuit 13 will be used to provide the output that equals the difference on the frequency (difference signal) between these two signals from the amplifying signal of HF amplifying circuit 11 output and local oscillation signal mixing from FM PLL circuit 2.To describe the operation of FM PLL circuit 2 below in detail.
Band pass filter 15 has the predetermined bandwidth of passing through, and is used for only extracting near preset frequency (for example, signal component 10.7MHz) from the output signal of mixting circuit 13.IF amplifying circuit 17 amplifies from the signal of band pass filter 15 outputs, with output FM IF signal.
Then, FM IF signal is by 3 demodulation of FM detecting circuit, so that FM to be provided stereo composite signal.This FM stereo composite signal comprises: the main channel signal of L+R signal; The L-R signal, it is the subchannel signal that the 38KHz subcarrier is carried out carrier suppressed AM modulation gained; With the 19KHz pilot signal.FM detecting circuit 3 for example is a quadrature detector.
FM stereo demodulation circuit 4 is from FM stereo composite signal demodulation L and R signal.L and R signal are amplified by low-frequency amplifier circuit 101,102, and corresponding audio output is derived from loud speaker 103,104 respectively.To describe the operation of FM stereo demodulation circuit 4 below in detail.
Now, will the operation that receive the AM signal be described.The AM signal that receives by antenna 59 is converted to AM IF signal by AM tuner pack 5.As shown in Figure 1, AM tuner pack 5 comprises HF amplifying circuit 51, mixting circuit 53, band pass filter 55 and IF amplifying circuit 57.Similar aforesaid FM tuner pack 1, AM tuner pack 5 provide AM IF signal to be used for demodulation AM audio signal to be applied to AM detecting circuit 7.AM detecting circuit 7 for example is an envelope detector.The AM audio signal is amplified by low-frequency amplifier circuit 105, and audio signal derives from loud speaker 106.Although from the loud speaker 106 that the loud speaker 103,104 that is used for FM broadcasting separates, shown in Figure 1 for convenience of description, can remove loud speaker 106, when receiving the AM signal, will import loud speaker 103,104 from the signal of low-frequency amplifier circuit 105 outputs.
(3) structure of FM stereo demodulation circuit and operation.
Now, the structure and the operation of aforesaid FM stereo demodulation circuit 4 will be described in detail.Fig. 2 is the detailed structure of FM stereo demodulation circuit 4.FM stereo demodulation circuit 4 as shown in Figure 2 comprises reference generator part 41, is used to produce the reference signal of hope; Strobe pulse generation circuit 42 is used to produce strobe signal, is used to separate the FM stereo composite signal; Pilot signal detection circuit 44 is used for detecting the pilot signal that is included in the FM stereo composite signal; With stereo separation circuit 43, be used for separating L and R signal from the FM stereo composite signal.
The VCO 88 that is included in the reference generator part 41 comprises oscillating circuit 91, quartz (controlled) oscillator 92 and variable capacitance diode 93.Come the oscillation signal frequency of self-oscillating circuit 91 to change in response to the load capacitance of the quartz (controlled) oscillator 92 that is connected to oscillating circuit 91.In this particular example, variable capacitance diode 93 is as the load capacitance of quartz (controlled) oscillator 92.The reversed bias voltage that is applied to variable capacitance diode 93 can change, and is used for the frequency of oscillation of control oscillation circuit 91.
By two frequency dividers, 81,82 frequency divisions, frequency divider 81,82 respectively has predetermined frequency dividing ratio from the oscillator signal of VCO 88.For example, first order frequency divider 81 has the frequency dividing ratio of " 15 ", and second level frequency divider 82 has the frequency dividing ratio of " 30 ".And second level frequency divider 82 provides a pair of signal that differs the frequency division of 180 ° of phase differences each other.The signal of two frequency divisions is provided to strobe pulse generation circuit 42.From one of two signals of frequency divider 82 output (Fig. 2 a) after by frequency divider 84 further frequency divisions, also be provided for pilot signal detection circuit 44, and another signal (b among Fig. 2) also is applied to phase comparator 86 after by frequency divider 83 further frequency divisions.
The PLL circuit is made of aforesaid VCO 88, frequency divider 81,82,83, phase comparator 86 and low pass filter 87.The oscillating operation of VCO 88 is controlled as follows: the reference signal of hope is synchronous with the pilot signal that is included in the FM stereo composite signal.
If setting the frequency dividing ratio of frequency divider 81,82,83 is " 15 ", " 30 " and " 2 ", the signal that then is applied to phase comparator 86 is that output from VCO 88 is by " 900 " (=15 * 30 * 2) frequency division.The oscillating operation Be Controlled of VCO 88 makes the signal of frequency division equal pilot signal frequency (19KHz).The result is that VCO 88 provides 17.1MHz reference signal, promptly equals 19KHz and multiply by 900.
When phase comparator 86 when frequency divider 83 receives the output signal that has with pilot signal same frequency and phase quadrature, phase comparator 86 provides the output with 50% duty ratio.When from the phase place of the output signal of frequency divider 83 and frequency when above-mentioned condition departs from, duty ratio from the output signal of phase comparator 86 departs from 50%, thereby change to the output voltage of VCO 88 by low pass filter 87, control equals above-mentioned condition from the phase place and the frequency of frequency divider 83.
Strobe pulse generation circuit 42 receives from the output signal of frequency divider 81 with from two frequency division output signals of frequency divider 82, provides two strobe signal (signal g and h in Fig. 2) synchronous with pilot signal to give stereo separation circuit 43.Two strobe signal have the frequency identical with the 38KHz subcarrier of subchannel, and 180 ° of phase differences are arranged each other.
Pilot signal detection circuit 44 based on these signals, detects the pilot signal that is included in the FM stereo composite signal from the output signal and the FM stereo composite signal of two frequency divisions of frequency divider 84 receptions.When detecting this pilot signal, pilot signal detection circuit 44 provides a high level signal, and it is provided to stereo separation circuit 43, also is used to driven for emitting lights diode 45.
Fig. 3 illustrates the signal waveform of the operation that is used to describe stereo separation circuit 43.Fig. 3 (a) is the waveform that is applied to the FM stereo composite signal of stereo separation circuit 43, Fig. 3 (b) is the waveform from one of two strobe signal of strobe pulse generation circuit 42, Fig. 3 (c) is the waveform from another strobe signal of strobe pulse generation circuit 42, Fig. 3 (d) is the waveform from the L signal of stereo separation circuit 43, and Fig. 3 (e) is the waveform from the R signal of stereo separation circuit 43.In order to simplify description, the L signal is sinusoidal wave, and the R signal is a square wave.
Shown in Fig. 3 (a), stereo composite signal comprises L and R signal.Attention in Fig. 3 (a) () symbolic representation L signal and (*) symbolic representation R signal.At Fig. 3 (d) and the L (e) and R signal be two strobe signal samplings based on Fig. 3 (b) and (c) respectively.
For example, stereo separation circuit 43 has a pair of linked switch (not shown), switches on or off in response to two strobe signal.In the moment that a strobe signal is applied in, one of switch is switched on, so that sample the L signal from the FM stereo composite signal.On the other hand, in the moment that another strobe signal is applied in, another switch is switched on, so that sample the R signal from the FM stereo composite signal.
As previously mentioned, reference generator part 41 constitutes the PLL circuit, comprises the VCO 88 with quartz (controlled) oscillator 92, thereby only synchronous with pilot signal, produces strobe signal exactly.Specifically, use the VCO 88 of quartz (controlled) oscillator 92 that a narrow variable frequency scope is arranged, thus even also can be exactly and pilot signal synchronized oscillation when being included in the faint and FM stereo composite signal of pilot signal in the FM stereo composite signal noise being arranged.The stable demodulation that this has guaranteed stereo audio signal is not subjected to the influence of noise etc.
In addition, be highly accurate from the reference signal of VCO 88, comprise minimum frequency fluctuation, because it and pilot signal are synchronous.The result is, the signal that reference signal is carried out frequency division can be used to the reference frequency signal of FMPLL circuit 2 and AM PLL circuit 6.The quartz (controlled) oscillator 92 that is used for VCO 88 can carefully not selected having very high frequency accuracy, thereby has reduced the element cost, because can use cheap quartz (controlled) oscillator.
Should notice that aforesaid VCO 88 constitutes first oscillator, the circuit that comprises frequency divider 81,82,83, phase comparator 86, low pass filter 87 and VCO 88 constitutes a PLL circuit, and the product of the frequency dividing ratio of three frequency dividers 81,82,83 is first frequency dividing ratios.
(4) structure of FM PLL circuit and operation
Now, aforesaid FM PLL circuit 2 is described.FM PLL circuit 2 is as shown in Figure 1 carried out the PLL operation by using from FM stereo demodulation circuit 4 by the reference signal of two frequency divider 24,22 frequency divisions as reference frequency signal.By the harmonic ringing of deriving from tuning control section 9, the frequency dividing ratio of inner variable frequency divider (back description) is variable, thereby the local oscillation signal that the frequency with hope is provided is to FM tuner pack 1.
First order frequency divider 24 has predetermined frequency dividing ratio (for example " 38 "), is used for 17.1MHz signal 38 frequency divisions from FM stereo demodulation circuit 4, thus the signal of acquisition 450KHz.Equally, second level frequency divider 22 has predetermined frequency dividing ratio (for example " 9 "), and being used for further will be from 450KHz signal 9 frequency division of first order frequency divider 24, thereby obtains the signal output of 50KHz.Signal from the 50KHz of second level frequency divider 22 is applied to FM PLL circuit 2, as the reference frequency signal of PLL action need.
The frequency dividing ratio of noting two frequency dividers 24,22 is set to, and the frequency that is applied to the reference frequency signal of FM PLL circuit 2 from second level frequency divider 22 equals by the Frequency Distribution of the FM broadcasting of predetermined integers frequency division at interval.In this manual, distributing the frequency interval of FM broadcasting frequency to be called as " Frequency Distribution of FM broadcasting at interval ", is 100KHz in the FM of Japan broadcasting.
Fig. 4 illustrates the more detailed block diagram of aforementioned FM PLL circuit 2.As shown in Figure 4, FM PLL circuit 2 comprises voltage controlled oscillator (VCO) 21, low pass filter 29, phase comparator 25 and variable frequency divider 27, it provide with from the synchronous local oscillation signal of the reference frequency signal of aforementioned frequency divider 22.
The local oscillation signal of deriving from VCO 21 is the output of FM PLL circuit 2, also is applied to phase comparator 25 after by variable frequency divider 27 frequency divisions.Phase comparator 25 is from variable frequency divider 27 received signals, receives reference frequency signals from frequency divider shown in Figure 1 22, thereby controls the frequency of oscillation of VCO 21 in the following manner, that is, make to differ minimum between these two signals.The result is, if be set to aforesaid 50KHz to the frequency of the reference frequency signal of phase comparator 25, the frequency of being taken advantage of by the frequency dividing ratio of variable frequency divider 27 that equals 50KHz is the frequency of oscillation of VCO 21.For example, if the frequency dividing ratio of variable frequency divider 27 is set to " 1680 ", equal 84MHz (=50KHz * 1680) from the frequency of the output local oscillation signal of VCO 21.
Tuning control section 9 provides harmonic ringing to set the frequency dividing ratio of the variable frequency divider 27 in the FM PLL circuit 2 based on the tuning instruction from the operation part 10 that comprises various operation keyss.
AM PLL circuit 6 among Fig. 1 has the structure identical with aforesaid FM PLL circuit 2, use reference frequency signal to carry out the PLL operation, this reference frequency signal is derived by a pair of frequency divider 24,23 frequency divisions from the reference signal from FM stereo demodulation circuit 4.The frequency dividing ratio of inner variable frequency divider is variable in response to the harmonic ringing that comes self-tuning control section 9, thereby provides the local oscillation signal with hope frequency to AM tuner pack 5.
Second level frequency divider 23 has predetermined frequency dividing ratio (for example, " 50 "), and being used for further will be from 450KHz signal 50 frequency division of first order frequency divider 24, thereby 9KHz is provided signal.Then, the 9KHz signal is applied to AM PLL circuit 6 reference frequency signals as the PLL action need.
The frequency dividing ratio of a pair of frequency divider 24,23 is set, so that equal by the Frequency Distribution of the AM broadcasting of predetermined integers frequency division at interval from the frequency of the reference frequency signal of second level frequency divider 23 to AM PLL circuit 6.In this manual, distributing the preset frequency of broadcasting frequency to be called as at interval " Frequency Distribution of AM broadcasting at interval ", is 9KHz in Japan.
In aforesaid radio receiver 100, the product of the frequency dividing ratio of two frequency dividers 22,24 is second frequency dividing ratios, and the product of the frequency dividing ratio of two frequency dividers 23,24 is three frequency division ratios.
Equally, in aforementioned FM PLL circuit 2, VCO 21 constitutes second oscillator, and variable frequency divider 27 constitutes first frequency divider, comprises that the circuit of VCO 21, variable frequency divider 27, phase comparator 25 and low pass filter 29 constitutes second phase-locked loop (PLL) circuit.
If the FM PLL circuit in Fig. 42 is applied directly to AM PLL circuit 6, the VCO 21 that is included in the AM PLL circuit 6 constitutes the 3rd oscillator, variable frequency divider 27 constitutes second frequency divider, comprises that the circuit of VCO 21, variable frequency divider 27, phase comparator 25 and low pass filter 29 constitutes the 3rd PLL circuit.
As mentioned above, the embodiment of radio receiver 100 does not use from the output signal that comprises the reference oscillator of quartz (controlled) oscillator independently as reference frequency signal, be applied to FM PLL circuit 2 and AMPLL circuit 6, be used to produce local oscillation signal, and be to use by reference signal is carried out frequency division in FM stereo demodulation circuit 4 reference signal that produces, thereby avoided using independent or special reference oscillator, reduced the element amount.Especially, if when radio receiver 100 is integrated on the Semiconductor substrate, can reduce can not be integrated the quantity such as outside elements that connects such as quartz (controlled) oscillators.
In FM PLL circuit 2, use synchronously produces pin-point accuracy and stable local oscillation signal from the reference signal of FM stereo demodulation circuit 4 by reference signal being carried out frequency division to obtain reference frequency signal, can simplifying with the pilot signal that is included in the FM stereo composite signal.Equally, the frequency dividing ratio of variable frequency divider 27 is variable, so that select the frequency of FM received signal.Similarly, also can obtain the local oscillation signal of pin-point accuracy and stable (low frequency drift) for AM PLL circuit 6, AM received signal frequency can change to the frequency of any hope.
As mentioned above, based on the pilot signal frequency with from the output frequency of FM PLL circuit 2 and AM PLL circuit 6, set output reference signal frequency from FM stereo demodulation circuit 4.
Specifically, from the following setting of reference signal frequency of VCO 88: the signal frequency by three frequency divider 81,82,83 frequency divisions from VCO 88 in FM stereo demodulation circuit 4 equals the pilot signal frequency.Equal at interval from the output reference signal frequency by two frequency dividers, 24,22 frequency divisions of FM stereo demodulation circuit 4 by the Frequency Distribution of the FM broadcasting of predetermined integers frequency division.Equal at interval from the reference signal frequency by two frequency divider 24,23 frequency divisions of FM stereo demodulation circuit 4 by the Frequency Distribution of the AM broadcasting of predetermined integers frequency division.Perhaps, the Frequency Distribution that is set at pilot signal frequency, FM broadcasting from the frequency of oscillation of the output reference signal of FM stereo demodulation circuit 4 at interval and the integral multiple of the Frequency Distribution least common multiple at interval of AM broadcasting.
By setting frequency of oscillation under these conditions from the output reference signal of FM stereo demodulation circuit 4, by reference frequency is carried out frequency division, can obtain the strobe signal that the FM demodulation needs, identical reference signal can be by frequency division to provide the reference frequency signal of FM PLL circuit 2 and AM PLL circuit 6, and the local oscillation signal that the frequency conversion of FM and AM received signal needs is derived from FM PLL circuit 2 and AM PLL circuit 6.
Notice that the present invention is not limited in the foregoing description, should be appreciated that, can carry out various corrections not breaking away under the theme of the present invention.For example, although radio receiver is designed to receive FM and AM signal in the above-described embodiments, also this invention can be applied to only receive the radio receiver of FM signal.In this case, antenna 59, AM tuner pack 5, AM detecting circuit 7, low-frequency amplifier circuit 105, loud speaker 106, AM PLL circuit 6 and frequency divider 23 can remove.
Equally, if do not receive the AM signal, then do not need to consider the local oscillation signal of AM broadcasting and the Frequency Distribution interval of AM broadcasting.Like this, can be only set from the frequency of the output reference signal of FM stereo demodulation circuit 4 based on the pilot signal frequency with from the frequency of the local oscillation signal of FM PLL circuit 2.Specifically, be set from the reference signal frequency of VCO 88 or from the reference signal frequency of FM stereo demodulation circuit 4, make the reference signal frequency from VCO 88 equal the pilot signal frequency, equal at interval by the Frequency Distribution of the FM broadcasting of predetermined integers frequency division from the reference signal frequency by two frequency divider 24,22 frequency divisions of FM stereo demodulation circuit 4 by three frequency divider 81,82,83 frequency divisions.Perhaps, be set at the integral multiple of the Frequency Distribution least common multiple at interval of pilot signal frequency and FM broadcasting from the reference signal frequency of FM stereo demodulation circuit 4.
Although the frequency dividing ratio of above-mentioned seven frequency dividers 22,23,24,81,82,83,84 is chosen as 9,50,38,15,30,2,2 respectively, these frequency dividing ratios can be according to the pilot signal frequency, be chosen as suitable value from the local oscillation signal frequency of FM PLL circuit 2 and AM PLL circuit 6.
Industrial applicability
As mentioned above, the present invention utilizes first oscillator and is included in leading in the FM stereo composite signal Frequently signal synchronized oscillation is used to oscillation output signal from first oscillator with second oscillator that vibrates, The local oscillation signal that second oscillator provides frequency conversion to need. The result is, the present invention does not need independently or specially The oscillator for generation of local oscillation signal, thereby reduce parts number. Specifically, work as radio receiver Circuit when being integrated on the Semiconductor substrate, the present invention can effectively reduce such as being used for oscillator The outside element that connects such as quartz (controlled) oscillator.
Equally, if construct first oscillator comprise as use quartz (controlled) oscillator voltage controlled oscillator One PLL circuit then can only produce strobe signal with pilot signal synchronously exactly.
In addition, if construct first oscillator comprise as use quartz (controlled) oscillator voltage controlled oscillator One PLL circuit then can obtain pin-point accuracy and the very vibration of low frequency fluctuation from this first oscillator Signal. The result is, used quartz (controlled) oscillator can carefully not select to have the high-frequency accuracy here, Thereby make it possible to use cheap quartz (controlled) oscillator, thereby reduced cost.
Claims (11)
1. radio receiver comprises: first oscillator is used for after the FM detection and the pilot signal synchronized oscillation that is included in the FM stereo composite signal; With second oscillator, be used for based on oscillator signal from described first oscillator, the local oscillation signal of the frequency conversion needs of FM received signal is provided.
2. radio receiver as claimed in claim 1, wherein said first oscillator is first phase-locked loop circuit, comprises voltage controlled oscillator, uses quartz (controlled) oscillator, produces the strobe signal that demodulation FM stereo composite signal needs.
3. radio receiver as claimed in claim 1, second phase-locked loop circuit wherein is provided, so that use oscillator signal from the frequency division of described first oscillator as reference frequency signal, described second phase-locked loop circuit comprises first frequency divider and described second oscillator with variable division ratio, is recently controlled by the frequency division that changes described frequency divider from the frequency of the local oscillation signal of described second oscillator.
4. radio receiver as claimed in claim 1, the frequency of oscillation of wherein said first oscillator is based on the pilot signal frequency with from the local oscillation signal frequency of described second oscillator and set.
5. radio receiver as claimed in claim 1, the frequency of oscillation of wherein said first oscillator is set, make to equal the pilot signal frequency by the output frequency of oscillation of the frequency dividing ratio frequency division of first frequency divider, equal at interval by the output frequency of oscillation of the frequency dividing ratio frequency division of second frequency divider by the Frequency Distribution of the FM broadcasting of predetermined integers frequency division from described first oscillator from described first oscillator.
6. radio receiver as claimed in claim 1, the frequency of oscillation of wherein said oscillator are set to the integral multiple of the Frequency Distribution least common multiple at interval of pilot signal frequency and FM broadcasting.
7. radio receiver as claimed in claim 1 wherein also provides the 3rd oscillator, to produce the local oscillation signal of the frequency conversion needs of AM received signal based on the oscillator signal from first oscillator.
8. radio receiver as claimed in claim 7, the 3rd phase-locked loop circuit wherein also is provided, use from the output signal of the frequency division of described first oscillator as reference frequency signal, comprise second frequency divider and described the 3rd oscillator with variable division ratio, the frequency division of controlling described second frequency divider recently changes the local oscillation signal frequency from described the 3rd oscillator.
9. radio receiver as claimed in claim 7, the frequency of oscillation of wherein said first oscillator is set by pilot signal frequency and local oscillation signal frequency from the described second and the 3rd oscillator.
10. radio receiver as claimed in claim 7, the frequency of oscillation of wherein said first oscillator is set, make and to equal the pilot signal frequency by the oscillation signal frequency of the first frequency dividing ratio frequency division from described first oscillator, equal at interval by the oscillation signal frequency of the second frequency dividing ratio frequency division from described first oscillator, equal at interval than the oscillation signal frequency of frequency division by three frequency division by the Frequency Distribution of the AM broadcasting of second integral frequency divisioil from described first oscillator by the Frequency Distribution of the FM broadcasting of first integral frequency divisioil.
11. radio receiver as claimed in claim 1, the frequency of oscillation of wherein said first oscillator are set to the integral multiple of the Frequency Distribution interval of pilot signal frequency, FM broadcasting and the Frequency Distribution least common multiple at interval that AM broadcasts.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22011397 | 1997-07-31 | ||
| JP220113/1997 | 1997-07-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1265242A true CN1265242A (en) | 2000-08-30 |
Family
ID=16746124
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 98807586 Pending CN1265242A (en) | 1997-07-31 | 1998-07-01 | Radio receiver |
Country Status (4)
| Country | Link |
|---|---|
| KR (1) | KR20010022059A (en) |
| CN (1) | CN1265242A (en) |
| TW (1) | TW396680B (en) |
| WO (1) | WO1999007091A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101552884B (en) * | 2008-03-31 | 2011-11-30 | 索尼株式会社 | Electronic apparatus, dispersion adjustment method of ic internal component section of electronic apparatus and ic |
| CN101589551B (en) * | 2007-01-22 | 2012-05-23 | Nxp股份有限公司 | An automatic radio tuning system and method |
| CN101552882B (en) * | 2008-04-03 | 2012-05-30 | 索尼株式会社 | Electronic apparatus, electronic-apparatus adjustment method and integrated circuit |
| CN104426556A (en) * | 2013-09-10 | 2015-03-18 | 上海特金信息科技有限公司 | Dual-mode voice demodulation equipment |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3462772B2 (en) * | 1998-11-30 | 2003-11-05 | 三洋電機株式会社 | Radio receiver |
| JP2002247462A (en) * | 2001-02-15 | 2002-08-30 | Funai Electric Co Ltd | Receiver |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5883446A (en) * | 1981-11-12 | 1983-05-19 | Matsushita Electric Ind Co Ltd | Receiver |
| JPS60223335A (en) * | 1984-04-20 | 1985-11-07 | Hitachi Ltd | Turner of am/fm receiver |
-
1998
- 1998-07-01 CN CN 98807586 patent/CN1265242A/en active Pending
- 1998-07-01 WO PCT/JP1998/002988 patent/WO1999007091A1/en not_active Application Discontinuation
- 1998-07-01 KR KR1020007000628A patent/KR20010022059A/en not_active Application Discontinuation
- 1998-07-29 TW TW87112441A patent/TW396680B/en not_active IP Right Cessation
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101589551B (en) * | 2007-01-22 | 2012-05-23 | Nxp股份有限公司 | An automatic radio tuning system and method |
| CN101552884B (en) * | 2008-03-31 | 2011-11-30 | 索尼株式会社 | Electronic apparatus, dispersion adjustment method of ic internal component section of electronic apparatus and ic |
| CN101552882B (en) * | 2008-04-03 | 2012-05-30 | 索尼株式会社 | Electronic apparatus, electronic-apparatus adjustment method and integrated circuit |
| CN104426556A (en) * | 2013-09-10 | 2015-03-18 | 上海特金信息科技有限公司 | Dual-mode voice demodulation equipment |
Also Published As
| Publication number | Publication date |
|---|---|
| TW396680B (en) | 2000-07-01 |
| KR20010022059A (en) | 2001-03-15 |
| WO1999007091A1 (en) | 1999-02-11 |
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| PB01 | Publication | ||
| C01 | Deemed withdrawal of patent application (patent law 1993) | ||
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