JP2007235346A - Device and method for demodulating angle, device and method for correction phase, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle demodulating device for reducing the distortion of a target signal which is obtained by demodulating a high frequency angle modulating signal, etc. <P>SOLUTION: A local oscillator 3I generates a first local oscillation signal. A phase shifter 3Q shifts the signal by 90° so as to generate a first phase shift signal. Mixers 4I and 4Q generate I channel and Q channel base band signals with the use of the first phase shift signal and the angle modulating signal. A local oscillation phase corrector 8 specifies the value of the second local oscillation signal which is generated by a local oscillator 7 and is not corrected yet, selects two values among a plurality of past values of the specified value and/or the present value of the uncorrected second local oscillation signal, and generates the two signals indicating the values as the corrected second local oscillation signal and second phase shift signal. Mixers 6I and 6Q mix the signals with the respective base band signals. An adder 9 adds mixture results so as to obtain an intermediate frequency signal. The intermediate frequency signal is used for demodulation by an FM wave detector 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an angle demodulating device, a phase correcting device, an angle demodulating method, a phase correcting method, and a program, and in particular, an angle demodulating device, a phase correcting device, an angle demodulating method, and a phase correcting method for accurately demodulating an angle modulated wave. And programs.

  As a method for demodulating an FM (Frequency Modulation) modulation signal, direct conversion is known (for example, see Patent Document 1). An FM receiver using the direct conversion method has a configuration shown in FIG. 3, for example.

  In the FM receiver shown in FIG. 3, the FM modulated signal received by the antenna 101 is supplied to the first mixers 104I and 104Q by the duplexer 102. The FM modulation signal is mixed with a pair of first local oscillation signals having phases different from each other by 90 degrees generated by the first local oscillator 103I and the phase shifter 103Q, and converted into a pair of baseband signals. The first local oscillation signal is set to the same frequency as the carrier frequency of the received signal.

  After the harmonic components of the baseband signal are cut by LPFs (Low Pass Filters) 105I and 105Q, the second mixers 106I and 106Q have a phase of 90 degrees between the second local oscillator 107I and the phase shifter 107Q. Each is mixed with a different pair of second local oscillation signals. Signals obtained by mixing are added to each other by an adder 108, and thereby converted into a single intermediate frequency signal.

  The intermediate frequency signal is supplied to an FM detector 111 via a BPF (Band Pass Filter) 109 and an IF (Intermediate Frequency) amplifier 110, and the FM detector 111 detects the intermediate frequency signal and is obtained by detection. Output an audio signal (target signal).

According to the direct conversion method, the configuration of an apparatus for demodulating an FM modulated signal can be simplified, and unlike superheterodyne, there is an advantage that there is no possibility of interference by a signal near the image frequency.
JP 2000-115265 A

  In the FM receiver having the above-described configuration shown in FIG. 3, the phase shift by the phase shifters 103Q and 107Q needs to be performed accurately, and the phase difference between the first local oscillation signals, the second When the phase difference between the local oscillation signals is not exactly 90 degrees and is shifted, the intermediate frequency signal and the target signal are distorted unless the shift is canceled out as a whole. However, it is difficult to manufacture a phase shifter that accurately performs phase shift as the frequency of the signal to be phase shifted is higher. Therefore, in the example of FIG. 3, since the frequency of the second local oscillation signal is usually higher than that of the first local oscillation signal, the phase shifter that performs the operation of the phase shifter 103Q accurately is the phase shifter. Manufacture is more difficult than a phase shifter that accurately operates the device 107Q. Therefore, in the above method, the target signal is likely to be distorted.

  The present invention has been made in view of the above circumstances, and an angle demodulation device, a phase correction device, an angle demodulation method, a phase correction method, and a program for reducing distortion of a target signal obtained by demodulating a high-frequency angle modulation signal The purpose is to provide.

In order to achieve this object, an angle demodulator according to a first aspect of the present invention provides:
First oscillation means for outputting a first local oscillation signal and a first phase-shifted signal that is substantially 90 degrees out of phase with the first local oscillation signal;
An angle modulation signal is obtained from the outside, the first local oscillation signal and the first phase shift signal are obtained from the first oscillation means, and the angle modulation signal and the first local oscillation signal are heterodyne mixed. Generating a first baseband signal corresponding to the result, and generating a second baseband signal corresponding to a result of heterodyne mixing of the angle modulation signal and the first phase-shifted signal;
A second oscillating means for outputting a second local oscillation signal and a second phase-shifted signal substantially different in phase by 90 degrees from the second local oscillation signal;
The first baseband signal is obtained from the first mixing means, the second local oscillation signal and the second phase-shifted signal are obtained from the second oscillation means. And a second mixing means for generating an intermediate frequency signal representing a sum of a heterodyne mixture of the second local oscillation signal and a heterodyne mixture of the second baseband signal and the second phase-shifted signal;
Demodulating means for generating an angle demodulated signal by acquiring and demodulating the intermediate frequency signal from the second mixing means,
The second oscillating means includes
Original oscillation means for generating an original oscillation signal corresponding to the second local oscillation signal before correction;
Delay means for acquiring the original oscillation signal and generating a plurality of delay signals corresponding to the original oscillation signal obtained by delaying a plurality of different delay amounts from each other;
Select any two of the original oscillation signal and / or each delayed signal, output one of the selected two signals as a corrected second local oscillation signal, and output the other to the second phase shift Selecting means for outputting as a signal,
It is characterized by that.

  According to such an angle demodulating device, the phase of the corrected second local oscillation signal and second phase-shifted signal is selected from the current value and / or the past value of the original oscillation signal. It is easily corrected by changing the piece. Therefore, according to such an angle demodulating device, demodulation by the direct conversion method is performed while distortion of the target signal is reduced.

Moreover, the phase correction apparatus according to the second aspect of the present invention provides:
Original oscillation means for generating an original oscillation signal corresponding to the local oscillation signal before correction;
Delay means for acquiring the original oscillation signal and generating a plurality of delay signals corresponding to the original oscillation signal obtained by delaying a plurality of different delay amounts from each other;
Select either one of the original oscillation signal and / or each delayed signal, output one of the two selected signals as a corrected local oscillation signal, and output the other as a phase shift signal Means,
It is characterized by that.

  If an angle demodulation device that performs direct conversion is configured using such a phase correction device, the phase of the corrected second local oscillation signal and second phase-shifted signal is the original oscillation in the angle modulation device. It is easily corrected by changing two of the current values and / or past values of the signal to be selected. Therefore, according to the angle modulation device using such a phase correction device, the distortion of the target signal is reduced and the demodulation by the direct conversion method is performed.

  In the angle demodulating device or the phase correcting device, the delay unit, for example, in response to a predetermined clock signal indicating a predetermined transition, latches the value of the original oscillation signal at the time of the transition, What is necessary is just to be comprised by the shift register which produces | generates the several signal showing each latched value as each delay signal.

An angle demodulation method according to the third aspect of the present invention is as follows.
A first oscillation step for outputting a first local oscillation signal and a first phase-shifted signal that is substantially 90 degrees out of phase with the first local oscillation signal;
An angle modulation signal is acquired from the outside, the first local oscillation signal and the first phase shift signal are acquired, and a first result corresponding to the result of heterodyne mixing of the angle modulation signal and the first local oscillation signal is obtained. A first mixing step of generating a baseband signal and generating a second baseband signal corresponding to a result of heterodyne mixing of the angle modulation signal and the first phase-shifted signal;
A second oscillation step for outputting a second local oscillation signal and a second phase-shifted signal that is substantially 90 degrees out of phase with the second local oscillation signal;
Obtaining the first and second baseband signals, obtaining the second local oscillation signal and the second phase-shifted signal, and heterodyne mixing the first baseband signal and the second local oscillation signal And a second mixing step for generating an intermediate frequency signal representing a sum of a heterodyne mixture of the second baseband signal and the second phase-shifted signal;
A demodulation step for generating an angle demodulated signal by acquiring and demodulating the intermediate frequency signal, and
The second oscillation step includes
An original oscillation step for generating an original oscillation signal corresponding to the second local oscillation signal before correction;
A delay step of acquiring the original oscillation signal and generating a plurality of delay signals corresponding to a plurality of different delay amounts of the original oscillation signal;
Select any two of the original oscillation signal and / or each delayed signal, output one of the selected two signals as a corrected second local oscillation signal, and output the other to the second phase shift A selection step of outputting as a signal,
It is characterized by that.

  According to such an angle demodulation method, the phase of the corrected second local oscillation signal and second phase-shifted signal is selected from the current value and / or the past value of the original oscillation signal. It is easily corrected by changing the piece. Therefore, according to such an angle demodulation method, demodulation by a direct conversion method is performed while distortion of the target signal is reduced.

The phase correction method according to the fourth aspect of the present invention is as follows:
An original oscillation step for generating an original oscillation signal corresponding to the local oscillation signal before correction;
A delay step of acquiring the original oscillation signal and generating a plurality of delay signals corresponding to a plurality of different delay amounts of the original oscillation signal;
Select either one of the original oscillation signal and / or each delayed signal, output one of the two selected signals as a corrected local oscillation signal, and output the other as a phase shift signal Comprising steps,
It is characterized by that.

  In the angle demodulation method using the direct conversion method using such a phase correction method, the phase of the corrected second local oscillation signal and second phase shift signal is the current value and / or the past of the original oscillation signal. It is easily corrected by changing two of the values to be selected. Therefore, according to the angle modulation method using such a phase correction method, demodulation by the direct conversion method is performed while distortion of the target signal is reduced.

A program according to the fifth aspect of the present invention is
Computer
First oscillation means for outputting a first local oscillation signal and a first phase-shifted signal that is substantially 90 degrees out of phase with the first local oscillation signal;
An angle modulation signal is obtained from the outside, the first local oscillation signal and the first phase shift signal are obtained from the first oscillation means, and the angle modulation signal and the first local oscillation signal are heterodyne mixed. Generating a first baseband signal corresponding to the result, and generating a second baseband signal corresponding to a result of heterodyne mixing of the angle modulation signal and the first phase-shifted signal;
A second oscillating means for outputting a second local oscillation signal and a second phase-shifted signal substantially different in phase by 90 degrees from the second local oscillation signal;
The first baseband signal is obtained from the first mixing means, the second local oscillation signal and the second phase-shifted signal are obtained from the second oscillation means. And a second mixing means for generating an intermediate frequency signal representing a sum of a heterodyne mixture of the second local oscillation signal and a heterodyne mixture of the second baseband signal and the second phase-shifted signal;
A program for functioning as demodulation means for generating an angle demodulated signal by acquiring and demodulating the intermediate frequency signal from the second mixing means,
The second oscillating means includes
Original oscillation means for generating an original oscillation signal corresponding to the second local oscillation signal before correction;
Delay means for acquiring the original oscillation signal and generating a plurality of delay signals corresponding to the original oscillation signal obtained by delaying a plurality of different delay amounts from each other;
Select any two of the original oscillation signal and / or each delayed signal, output one of the selected two signals as a corrected second local oscillation signal, and output the other to the second phase shift Selecting means for outputting as a signal,
It is characterized by that.

  According to the computer that executes such a program, the phase of the corrected second local oscillation signal and second phase-shifted signal is selected from the current value and / or the past value of the original oscillation signal. It is easily corrected by changing the two. Therefore, according to such a program, demodulation by the direct conversion method is performed while distortion of the target signal is reduced.

A program according to the sixth aspect of the present invention is
Computer
Original oscillation means for generating an original oscillation signal corresponding to the local oscillation signal before correction;
Delay means for acquiring the original oscillation signal and generating a plurality of delay signals corresponding to the original oscillation signal obtained by delaying a plurality of different delay amounts from each other;
Select either one of the original oscillation signal and / or each delayed signal, output one of the two selected signals as a corrected local oscillation signal, and output the other as a phase shift signal Means,
It is for making it function.

  If an angle demodulator that performs direct conversion is configured using a computer that executes such a program, in the angle modulator, the phase of the corrected second local oscillation signal and second phase-shifted signal is: It is easily corrected by changing two of the current oscillation signal and / or past values to be selected. Therefore, if angle demodulation is performed using such a program, demodulation by the direct conversion technique is performed while distortion of the target signal is reduced.

  According to the present invention, an angle demodulation device, a phase correction device, an angle demodulation method, a phase correction method, and a program for reducing distortion of a target signal obtained by demodulating a high-frequency angle modulation signal are realized.

  Hereinafter, an angle demodulating apparatus and an angle demodulating method according to an embodiment of the present invention will be described using an FM (Frequency Modulation) receiver as an example.

FIG. 1 shows an example of the configuration of an FM receiver according to an embodiment of the present invention.
As shown in the figure, this FM receiver includes an antenna 1, a duplexer 2, local oscillators 3I and 7, phase shifters 3Q, mixers 4I, 4Q, 6I and 6Q, and an LPF (Low Pass Filter). 5I and 5Q, a local oscillation phase correction unit 8, an adder 9, a BPF (Band Pass Filter) 10, an IF (Intermediate Frequency) amplifier 11, and an FM detector 12.

  When a signal (RF signal) received by the antenna 1 is supplied from the antenna 1, the duplexer 2 supplies this RF signal to the mixers 4I and 4Q.

  The local oscillator 3I is composed of, for example, a crystal oscillator or the like, generates a first local oscillation signal having substantially the same frequency as the carrier frequency of the signal received by the antenna 1, and supplies the first local oscillation signal to the mixer 4I and the phase shifter 3Q. Supply.

  When the first local oscillation signal is supplied from the local oscillator 3I, the phase shifter 3Q generates a first phase shift signal that is a signal obtained by substantially delaying the phase of the first local oscillation signal by 90 degrees, and the mixer 4Q To supply.

  The mixers 4I and 4Q have substantially the same configuration. The mixer 4I generates a signal (I channel baseband signal) corresponding to the result of heterodyne mixing of the RF signal supplied from the duplexer 2 and the first local oscillation signal supplied from the local oscillator 3I, and the LPF 5I. To supply. The mixer 4Q generates a signal (Q channel baseband signal) corresponding to the result of heterodyne mixing of the RF signal supplied from the duplexer 2 and the first phase-shifted signal supplied from the phase shifter 3Q. Supply to LPF5Q.

  The LPFs 5I and 5Q have substantially the same configuration. The LPFs 5I and 5Q filter the I channel baseband signal or the Q channel baseband signal supplied from the mixer 4I or 4Q. Specifically, the LPF 5I removes a frequency component exceeding the upper limit of the band of an AF signal to be reproduced, which is to be reproduced, from the I channel baseband signal, and supplies the remaining frequency component to the mixer 6I. The LPF 5Q removes the frequency component exceeding the upper limit of the band of the AF signal to be reproduced from the Q channel baseband signal, and supplies the remaining frequency component to the mixer 6Q.

The mixers 6I and 6Q have substantially the same configuration.
The mixer 6I has a frequency corresponding to the result of heterodyne mixing of the signal supplied from the LPF 5I and the corrected second local oscillation signal (described later) supplied from the local phase correction unit 8 with these two frequencies. A signal representing a component substantially equal to the sum (or difference) of the frequencies of the signals is generated and supplied to the adder 9.
The mixer 6Q has a frequency corresponding to the result of heterodyne mixing of the signal supplied from the LPF 5Q and a second phase-shifted signal supplied from the local phase correction unit 8 with the frequency of these two signals. A signal representing a component substantially equal to the sum (or difference) is generated and supplied to the adder 9.

  The local oscillator 7 is composed of, for example, a crystal oscillator or the like, generates an uncorrected second local oscillation signal having a frequency substantially equal to a predetermined intermediate frequency, and supplies the second corrected oscillation signal to the local phase correction unit 8. The intermediate frequency corresponds to the carrier frequency of the IF signal described later.

The local phase correction unit 8 obtains an uncorrected second local oscillation signal from the local oscillator 7 and, based on the uncorrected second local oscillation signal, the corrected second local oscillation signal and the second shift signal. And a phase signal. Then, the corrected second local oscillation signal is supplied to the mixer 6I, and the second phase-shifted signal is supplied to the mixer 6Q.
The corrected second local oscillation signal and the second phase-shifted signal are generated by delaying the uncorrected second local oscillation signal by a plurality of different delay amounts, and the uncorrected second local oscillation signal. Any two of the local oscillation signals themselves are selected and output as corrected second local oscillation signals and second phase-shifted signals.

  Specifically, the local oscillation phase correction unit 8 has a configuration shown in FIG. That is, the local oscillation phase correcting unit 8 includes a clock generating unit CLK, an I channel shift register SRI, a Q channel shift register SRQ, selectors SELI and SERQ, and a control unit CTRL.

  The clock generation unit CLK is composed of, for example, a crystal oscillator, and continuously generates a clock signal having a frequency sufficiently higher than the above-described uncorrected second local oscillation signal, and generates an I channel shift register SRI and a Q channel shift. Supply to register SRQ.

  The I channel shift register SRI and the Q channel shift register SRQ have substantially the same configuration. The I-channel shift register SRI (or Q-channel shift register SRQ) is the second uncorrected second local portion at the latest past n times (n is a predetermined natural number) when the clock signal rises from the low level to the high level. A total of n values taken by the oscillation signal are latched. Then, n data indicating these n values are supplied to the selector SELI (or the selector SERQ). Specifically, the I-channel shift register SRI (or Q-channel shift register SRQ), for example, selects data indicating a new value at the kth (k is an integer from 1 to n) among the n pieces of data, and selects the selector SELI. (Or selector SELQ) is supplied to a data input terminal Dk described later.

  Specifically, the I channel shift register SRI only needs to be composed of n flip-flops FI1 to FIn, for example, as shown in FIG. Similarly, the Q channel shift register SRQ only needs to be composed of n flip-flops FQ1 to FQn.

The flip-flops FI1 to FIn and FQ1 to FQn have substantially the same configuration, and each includes a clock input terminal CK, a data input terminal D, and a data output terminal Q.
Each flip-flop latches the logical value of the signal supplied to its own data input terminal D when the signal supplied to its own clock input terminal CK rises from low level to high level. The signal indicating the logical value is continuously output from its own data output terminal Q until the signal supplied to the clock input terminal CK rises again.

A clock generator CLK is connected to each clock input terminal CK of the flip-flops FI1 to FIn and FQ1 to FQn, and a clock signal is supplied.
A local oscillator 7 is connected to each data input terminal of the flip-flops FI1 and FQ1, and an uncorrected second local oscillation signal is supplied.
A data output terminal Q of the flip-flop FIk is connected to a data input terminal Dk, which will be described later, of the selector SELI. The data output terminal Q of the flip-flop FQk is connected to a data input terminal Dk, which will be described later, of the selector SELQ.
The data output terminal Q of the flip-flop FIk (where k ≠ n) is also connected to the data input terminal D of the flip-flop FI (k + 1), and the data output terminal Q of the flip-flop FQk (where k ≠ n) is It is also connected to the data input terminal D of the flip-flop FQ (k + 1).

The selectors SELI and SERQ have substantially the same configuration, and each has a total of (n + 1) data input terminals D0 to Dn, one data output terminal Q, 1 Control input terminals C.
The selector SELI or SERQ outputs any data specified by the control signal supplied to its own control input terminal C among the data supplied to its own data input terminals D0 to Dn. Output from Q.

As described above, data indicating the kth new value among n data stored in the I channel shift register SRI (or Q channel shift register SRQ) is supplied to the data input terminal Dk of the selector SELI (or selector SERQ). The A local oscillator 7 is connected to each data input terminal D0 of the selectors SELI and SERQ, and an uncorrected second local oscillation signal is supplied to each.
The data output terminal Q of the selector SELI is connected to the mixer 6I, and supplies the signal specified by the control signal to the mixer 6I as the corrected second local oscillation signal.
The data output terminal Q of the selector SELQ is connected to the mixer 6Q, and supplies a signal specified by the control signal to the mixer 6I as a second phase shift signal.

  The control unit CTRL includes, for example, a processor such as a CPU (Central Processing Unit), a dedicated logic circuit, or a switch, and generates the above-described control signal for each of the selectors SELI and SERQ. Then, the control signal generated for the selector SELI is supplied to the control input terminal C of the selector SELI, and the control signal generated for the selector SERQ is supplied to the control input terminal C of the selector SERQ.

Any method can be used for the control unit CTRL to determine the content indicated by the control signal (that is, the designated content for the selector SELI or SERQ to output which data is supplied to each data input terminal).
Therefore, for example, the control unit CTRL may determine the content indicated by the control signal according to the operation of the operator, or may determine according to the data supplied from the outside via an arbitrary interface circuit. In addition, the processor constituting the control unit CTRL may determine the content indicated by the control signal according to the value obtained as a result of other processing executed by itself.

The optimum content shown by the control signal is, for example, a signal band of an AF signal described later obtained from the FM detector 12 by causing the antenna 1 to receive a signal obtained by frequency-modulating a predetermined single tone as an RF signal. The noise ratio (S / N ratio) may be measured by a known method, and the content that maximizes the S / N ratio may be specified.
Then, an operator may operate the control unit CTRL so that the specified contents are set, or an external device that automatically generates the above-described measurement or data representing the measurement result is provided. The content that maximizes the S / N ratio described above may be specified, and data indicating the specified content may be supplied to the control unit CTRL. Or the processor which comprises control part CTRL may perform the process for implement | achieving a part of function of the said apparatus, and may determine the content which a control signal shows according to the value obtained as a result of this process.

The adder 9 generates a signal representing the sum of the signals supplied from the mixers 6I and 6Q and supplies the signal to the BPF 10.
The BPF 10 filters the signal supplied from the adder 9. Specifically, the BPF 10 supplies the above-mentioned band component in the vicinity of the intermediate frequency to the IF amplifier 11 in the signal supplied from the adder 9 and substantially blocks the other components.
The IF amplifier 11 amplifies the component (IF signal) supplied from the BPF 10 and supplies the amplified component to the FM detector 12.

  The FM detector 12 includes a ratio detector, a quadrature demodulator circuit and other arbitrary FM detector circuits, an AF (Audio Frequency) amplifier, a speaker, and the like. The frequency shift of the signal supplied from the IF amplifier 11 is changed to an amplitude. The IF signal is FM demodulated by converting and the AF signal obtained by the demodulation is output as an output signal of the FM receiver and reproduced.

(Operation)
Next, the operation of this FM receiver will be described.
When the FM modulation signal to be received by the FM receiver induces an RF signal in the antenna 1, the duplexer 2 supplies the RF signal to the mixers 4I and 4Q.
On the other hand, the mixer 4I is supplied with a first local oscillation signal generated by the local oscillator 3I, and the mixer 4Q has a first shift signal corresponding to a signal delayed substantially 90 degrees in phase. A phase signal is supplied from the phase shifter 3Q.

  The mixer 4I generates an I channel baseband signal. The I channel baseband signal generated by the mixer 4I is filtered by the LPF 5I and then supplied to the mixer 6I. The mixer 4Q generates a Q channel baseband signal. The Q channel baseband signal generated by the mixer 4Q is filtered by the LPF 5Q and then supplied to the mixer 6Q. The frequency of the carrier component of the FM modulation signal included in the I channel baseband signal and the Q channel baseband signal is substantially zero.

  The local oscillation phase correction unit 8 acquires an uncorrected second local oscillation signal generated by the local oscillator 7, stores a plurality of past values thereof, and has corrected a signal indicating one of the stored values. The second local oscillation signal is supplied to the mixer 6I, and a signal indicating any value different from this value is supplied to the mixer 6Q as the second phase shift signal.

The mixer 6I is a component whose frequency is substantially equal to the sum (or difference) of the frequencies of these two signals among the signals obtained by heterodyne mixing the signal supplied by the LPF 5I and the corrected second local oscillation signal. Is generated and supplied to the adder 9.
The mixer 6Q is a signal representing a component whose frequency is substantially equal to the sum (or difference) of the frequencies of these two signals among signals obtained by heterodyne mixing the signal supplied by the LPF 5Q and the second phase-shifted signal. Is supplied to the adder 9.

The adder 9 generates a signal that represents the sum of the signals supplied from the mixers 6I and 6Q. This signal is filtered by the BPF 10 to become an IF signal, and the IF signal is amplified by the IF amplifier 11. The frequency of the carrier wave component of the FM modulated signal included in the IF signal is substantially equal to the frequency of the second local oscillation signal.
The IF signal amplified by the IF amplifier 11 is FM demodulated by the FM detector 12, and the AF signal obtained by the demodulation is output as an output signal of the FM receiver and reproduced.

If the phase difference between the corrected second local oscillation signal and the second phase-shifted signal is appropriately set by the local phase correction unit 8, the FM received by the FM receiver as a result of the operation described above. The modulation signal is demodulated, and the sound represented by the AF signal is appropriately reproduced.
Specifically, for example, when the phase difference of the first phase shift signal with respect to the first local oscillation signal is (90 + α) [degrees], and there is a shift in the amount of phase shift of + α [degrees], the correction is performed. If the phase difference of the second phase shift signal with respect to the already completed second local oscillation signal is set to (90−α) [degrees], the AF signal distortion due to the phase shift amount is almost eliminated. It can be said that.

Then, the above-described local phase correction unit 8 selects any two of the past plural values of the uncorrected second local oscillation signal and the current value of the uncorrected second local oscillation signal. Since the two signals indicating the selected values are supplied as the corrected second local oscillation signal and the second phase shift signal, the corrected second local oscillation signal and the second phase shift signal are supplied. It is easy to adjust the phase difference.
Therefore, for example, even when the phase shifter 3Q is deteriorated and the phase of the first local oscillation signal is not accurately shifted by 90 degrees, the deterioration can be compensated and the FM modulation signal can be accurately demodulated. Therefore, it is easy to reset the phase difference between the corrected second local oscillation signal and the second phase shift signal.

Note that the configuration of the FM receiver is not limited to that described above.
For example, the duplexer 2 may include an A / D (Analog-to-Digital) converter, a DSP (Digital Signal Processor), and a CPU (Central Processing Unit). Further, the FM detector 12 may be composed of a DSP or CPU and a D / A (Digital-to-Analog) converter. And a part or all of the function of the other component of this FM receiver may be performed by DSP or CPU.

Further, the FM receiver does not need to acquire the FM modulated signal from the antenna 1, and may acquire the FM modulated signal from a wired line, for example.
The FM receiver may demodulate a PM (Phase Modulation) modulation signal. In this case, the FM detector 12 may include, for example, an integration circuit for integrating the AF signal obtained by FM demodulation of the IF signal.
The selectors SELI and SERQ may not treat the current value of the uncorrected second local oscillation signal as a selection target.

  Although the angle demodulating device and the angle demodulating method according to the present invention have been described above, the angle demodulating device according to the present invention can be realized by using a normal computer system without using a dedicated system. For example, by installing the program from a medium (flexible disk, CD-ROM, etc.) storing a program for executing the above-described operation in a personal computer including an A / D converter and a D / A converter, An FM receiver that executes the above-described processing can be configured.

Further, for example, this program may be uploaded to a bulletin board (BBS) of a communication line and distributed via the communication line. Also, a carrier wave is modulated by a signal representing this program, and the obtained modulated wave is A device that transmits and receives the modulated wave may demodulate the modulated wave to restore these programs.
The above-described processing can be executed by starting this program and executing it under the control of the OS in the same manner as other application programs.

  When the OS shares a part of the processing, or when the OS constitutes a part of one component of the present invention, a program excluding the part is stored in the recording medium. May be. Also in this case, in the present invention, it is assumed that the recording medium stores a program for executing each function or step executed by the computer.

It is a figure which shows the structure of the FM receiver which concerns on embodiment of this invention. It is a figure which shows the structure of a local oscillation phase correction | amendment part. It is a figure which shows the structure of the conventional FM receiver.

Explanation of symbols

1 antenna 2 duplexer 3I, 7 local oscillator 3Q phase shifter 4I, 4Q, 6I, 6Q mixer 5I, 5Q LPF
8 Local phase correction unit CLK clock generation unit SRI I channel shift register SRQ Q channel shift register FI1 to FIn, FQ1 to FQn flip-flop SELI, SERQ selector CTRL control unit 9 Adder 10 BPF
11 IF amplifier 12 FM detector

Claims (8)

First oscillation means for outputting a first local oscillation signal and a first phase-shifted signal that is substantially 90 degrees out of phase with the first local oscillation signal;
An angle modulation signal is obtained from the outside, the first local oscillation signal and the first phase shift signal are obtained from the first oscillation means, and the angle modulation signal and the first local oscillation signal are heterodyne mixed. Generating a first baseband signal corresponding to the result, and generating a second baseband signal corresponding to a result of heterodyne mixing of the angle modulation signal and the first phase-shifted signal;
A second oscillating means for outputting a second local oscillation signal and a second phase-shifted signal substantially different in phase by 90 degrees from the second local oscillation signal;
The first baseband signal is obtained from the first mixing means, the second local oscillation signal and the second phase-shifted signal are obtained from the second oscillation means. And a second mixing means for generating an intermediate frequency signal representing a sum of a heterodyne mixture of the second local oscillation signal and a heterodyne mixture of the second baseband signal and the second phase-shifted signal;
Demodulating means for generating an angle demodulated signal by acquiring and demodulating the intermediate frequency signal from the second mixing means,
The second oscillating means includes
Original oscillation means for generating an original oscillation signal corresponding to the second local oscillation signal before correction;
Delay means for acquiring the original oscillation signal and generating a plurality of delay signals corresponding to the original oscillation signal obtained by delaying a plurality of different delay amounts from each other;
Select any two of the original oscillation signal and / or each delayed signal, output one of the selected two signals as a corrected second local oscillation signal, and output the other to the second phase shift Selecting means for outputting as a signal,
An angle demodulator characterized by that. In response to a predetermined clock signal indicating a predetermined transition, the delay means latches the value of the original oscillation signal at the time of the transition, and outputs a plurality of signals representing the latched values to the delay signals. It consists of a shift register that generates as
The angle demodulator according to claim 1. Original oscillation means for generating an original oscillation signal corresponding to the local oscillation signal before correction;
Delay means for acquiring the original oscillation signal and generating a plurality of delay signals corresponding to the original oscillation signal obtained by delaying a plurality of different delay amounts from each other;
Select either one of the original oscillation signal and / or each delayed signal, output one of the two selected signals as a corrected local oscillation signal, and output the other as a phase shift signal Means,
A phase correction apparatus. In response to a predetermined clock signal indicating a predetermined transition, the delay means latches the value of the original oscillation signal at the time of the transition, and outputs a plurality of signals representing the latched values to the delay signals. It consists of a shift register that generates as
The phase correction apparatus according to claim 3. A first oscillation step for outputting a first local oscillation signal and a first phase-shifted signal that is substantially 90 degrees out of phase with the first local oscillation signal;
An angle modulation signal is acquired from the outside, the first local oscillation signal and the first phase shift signal are acquired, and a first result corresponding to the result of heterodyne mixing of the angle modulation signal and the first local oscillation signal is obtained. A first mixing step of generating a baseband signal and generating a second baseband signal corresponding to a result of heterodyne mixing of the angle modulation signal and the first phase-shifted signal;
A second oscillation step for outputting a second local oscillation signal and a second phase-shifted signal that is substantially 90 degrees out of phase with the second local oscillation signal;
Obtaining the first and second baseband signals, obtaining the second local oscillation signal and the second phase-shifted signal, and heterodyne mixing the first baseband signal and the second local oscillation signal And a second mixing step for generating an intermediate frequency signal representing a sum of a heterodyne mixture of the second baseband signal and the second phase-shifted signal;
A demodulation step for generating an angle demodulated signal by acquiring and demodulating the intermediate frequency signal, and
The second oscillation step includes
An original oscillation step for generating an original oscillation signal corresponding to the second local oscillation signal before correction;
A delay step of acquiring the original oscillation signal and generating a plurality of delay signals corresponding to a plurality of different delay amounts of the original oscillation signal;
Select any two of the original oscillation signal and / or each delayed signal, output one of the selected two signals as a corrected second local oscillation signal, and output the other to the second phase shift A selection step of outputting as a signal,
An angle demodulation method characterized by the above. An original oscillation step for generating an original oscillation signal corresponding to the local oscillation signal before correction;
A delay step of acquiring the original oscillation signal and generating a plurality of delay signals corresponding to a plurality of different delay amounts of the original oscillation signal;
Select either one of the original oscillation signal and / or each delayed signal, output one of the two selected signals as a corrected local oscillation signal, and output the other as a phase shift signal Comprising steps,
A phase correction method characterized by the above. Computer
First oscillation means for outputting a first local oscillation signal and a first phase-shifted signal that is substantially 90 degrees out of phase with the first local oscillation signal;
An angle modulation signal is obtained from the outside, the first local oscillation signal and the first phase shift signal are obtained from the first oscillation means, and the angle modulation signal and the first local oscillation signal are heterodyne mixed. Generating a first baseband signal corresponding to the result, and generating a second baseband signal corresponding to a result of heterodyne mixing of the angle modulation signal and the first phase-shifted signal;
A second oscillating means for outputting a second local oscillation signal and a second phase-shifted signal substantially different in phase by 90 degrees from the second local oscillation signal;
The first baseband signal is obtained from the first mixing means, the second local oscillation signal and the second phase-shifted signal are obtained from the second oscillation means. And a second mixing means for generating an intermediate frequency signal representing a sum of a heterodyne mixture of the second local oscillation signal and a heterodyne mixture of the second baseband signal and the second phase-shifted signal;
A program for functioning as demodulation means for generating an angle demodulated signal by acquiring and demodulating the intermediate frequency signal from the second mixing means,
The second oscillating means includes
Original oscillation means for generating an original oscillation signal corresponding to the second local oscillation signal before correction;
Delay means for acquiring the original oscillation signal and generating a plurality of delay signals corresponding to the original oscillation signal obtained by delaying a plurality of different delay amounts from each other;
Select any two of the original oscillation signal and / or each delayed signal, output one of the selected two signals as a corrected second local oscillation signal, and output the other to the second phase shift Selecting means for outputting as a signal,
A program characterized by that. Computer
Original oscillation means for generating an original oscillation signal corresponding to the local oscillation signal before correction;
Delay means for acquiring the original oscillation signal and generating a plurality of delay signals corresponding to the original oscillation signal obtained by delaying a plurality of different delay amounts from each other;
Select either one of the original oscillation signal and / or each delayed signal, output one of the two selected signals as a corrected local oscillation signal, and output the other as a phase shift signal Means,
Program to make it function.

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