JP2000082980A - Phase inversion detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase inversion detection device detecting a phase inversion signal whose frequency is not specified and/or whose frequency error is large. SOLUTION: This device is provided with a phase estimation part 8 storing the complex numeric values of continuous three periods, which are given from a discrete Fourier transformation part 2, calculating a phase difference between the first period and the last period in the three periods, adding the calculated phase difference to the phase of the period previous to an estimation period by two so as to estimate the phase of the estimation period and a phase inversion detection part 9 comparing the phase of the complex numeric value from the discrete Fourier transformation part 2 with the estimated phase from the phase estimation part 8 and detecting the inversion of the phase when the phases have the phase difference of a degree that inversion is considered to occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase inversion detecting apparatus, and is suitably applied to, for example, a system for detecting a disabling signal for stopping the operation of an echo canceller.

[0002]

2. Description of the Related Art For example, an echo canceller inserted into a communication line is operated during voice communication, and is stopped during data communication by a disabling signal from a modem connected to the communication line. Here, the disabling signal is a signal of a specific frequency of 2100 Hz whose phase is inverted at an interval of 450 ± 25 ms for a predetermined time.

Conventionally, as a method of detecting such a signal, an input signal is supplied to a phase locked loop through a 2100 Hz band-pass filter, and the polarity of the control signal generated on the basis of the phase inverted is inverted in the phase locked loop. Detect
The detection was made based on whether or not this polarity inversion occurred in 450 ± 25 ms.

[0004]

However, since such a conventional detection method uses a phase synchronization circuit for the detection means, it is premised that the disabled signal has a specific frequency of 2100 Hz, and further, its frequency error is reduced. It was possible to detect when it was small.

However, in practice, when the frequency of the signal to be detected is not specified, or when the frequency is specified,
Depending on the accuracy of the device on the transmission side, the condition of the transmission path, and the like, the frequency error of the signal to be detected may be large, and the conventional detection method has a problem that it is difficult to detect the signal in these cases. .

Further, in the above description, the description has been made on the assumption that the disabling signal is detected. However, in general, a signal whose phase is irregularly inverted (hereinafter, referred to as a "phase inverted signal")
In the case where a phase-locked loop is used as the detecting means, the same problem will naturally occur.

For this reason, there has been a demand for a phase inversion detecting device capable of detecting a phase inversion signal whose frequency is not specified and / or whose frequency error is large.

[0008]

According to a first aspect of the present invention, there is provided a phase inversion detecting apparatus for detecting a phase inversion in a signal whose phase is inverted. And a phase inversion detecting means for detecting a phase inversion when the estimated phase and the current detected phase have a phase difference within a predetermined range based on the estimated phase. .

According to a second aspect of the present invention, there is provided a phase inversion detecting device for detecting phase inversion in a signal whose phase is inverted, wherein the level of an input signal exceeds a first predetermined value, and / or A phase inversion detecting means for detecting a time point at which the time falls below a second predetermined value smaller than the predetermined value, and detecting a phase inversion when an interval between the detected time points is out of a predetermined range. I do.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (A) First Embodiment Hereinafter, a first embodiment in which a phase inversion detecting device according to the present invention is applied to a phase inversion detecting device for detecting phase inversion of a phase inversion signal will be described.
The embodiment will be described in detail with reference to the drawings.

(A-1) Description of Configuration FIG. 1 is a block diagram showing the configuration of the phase inversion detection device according to the first embodiment. In FIG. 1, the phase inversion detecting device includes a discrete Fourier transform unit (“DFT” in the figure) 2,
An input signal amplitude detection unit 3 having an absolute value detection unit (“ABS” in the figure) 4 and an amplitude detection unit 5; an input signal phase inversion detection unit 7 having a phase estimation unit 8 and a phase inversion detection unit 9; And a phase inversion detection unit 11.

First, the connection correspondence between the components will be described. The input signal 1 is provided to a discrete Fourier transform unit 2, which is connected to an input signal amplitude detector 3 and an input signal phase inversion detector 7. The amplitude detection signal 6 output from the input signal amplitude detection unit 3 is provided to the input signal phase inversion detection unit 7 and the amplitude / phase inversion detection unit 11, whereas the amplitude detection signal 6 is output from the input signal phase inversion detection unit 7. The phase inversion detection signal 10 is output from the amplitude / phase inversion detection unit 11.
Given to. Further, the amplitude / phase inversion detecting section 11 outputs an output signal 12.

Next, each component will be described.

The discrete Fourier transform unit 2 performs a Fourier transform on the given input signal 1 and detects a level change of a frequency of interest (frequency of a phase-inverted signal to be detected) in the converted frequency band. It outputs a complex value x + iy indicating the amplitude and phase for each certain section in which the level changes. The amplitude is (x ² + y ² ) ^1/2 ,
The phase can be calculated by arctan (y / x). In addition, in order to make the notation of the complex value x + iy of the output easy to understand for explanation, the amplitude and phase of the converted section are denoted by r and θ, and may be denoted by re ^iθ .

The input signal amplitude detecting section 3 includes an absolute value calculating section 4 and an amplitude detecting section 5 therein.
Is to detect whether or not the amplitude r of the complex value re ^iθ given by is within a predetermined range. The output of the amplitude detection signal 6 takes a true or false logical value. Here, the signal becomes true if the amplitude r is within a predetermined range, and becomes false if the amplitude r is out of the predetermined range.

The absolute value detecting section 4 includes a discrete Fourier transform section 2
^Is to detect the amplitude r, which is the absolute value component, from the complex value re ^iθ given by. Its output is the amplitude r
Is a real value indicating the magnitude of.

The amplitude detector 5 detects whether or not the amplitude r given from the absolute value detector 4 is within a predetermined range. Its output takes a Boolean value,
This output is the amplitude detection signal 6 output from the input signal amplitude detection unit 3. When the amplitude r is within the predetermined range, the output is true, and when the amplitude r is outside the predetermined range, the output is false.

The input signal phase inversion detecting section 7 has a phase estimating section 8 and a phase inversion detecting section 9 therein, and performs a discrete Fourier transform based on the logical value of the amplitude detection signal 6 from the input signal amplitude detecting section 3. This is to detect whether or not the phase with the complex value re ^iθ from the section 2 has been inverted. Here, the input signal phase inversion detection unit 7 performs the detection operation only when the logical value of the amplitude detection signal 6 is true, that is, when the amplitude r of the input signal 1 is within a predetermined range. The output of the phase inversion detection signal 10 has a true or false logical value. Here, the phase becomes true if phase inversion is detected, and false if phase inversion is not detected.

The phase estimating section 8 stores the complex values of three consecutive sections provided from the discrete Fourier transform section 2 and calculates the phase difference between the first section and the last section of the three sections.
By adding the calculated phase difference to the phase of the section immediately before the section to be estimated, the phase of the estimated section is estimated, and the estimated phase is provided to the phase inversion detecting unit 9.

The phase inversion detecting section 9 compares the phase of the complex value from the discrete Fourier transform section 2 with the phase estimated from the phase estimating section 8 and finds a phase difference such that inversion is considered to have occurred. Is detected, the phase inversion is detected. Its output takes a true or false logical value, and this output is an output when the input signal phase inversion detection unit 7 operates. Here, if the phase inversion is detected, the output becomes true,
If not detected, the output will be false.

The amplitude / phase reversal detection unit 11 continues based on the logic value of the amplitude detection signal 6 from the input signal amplitude detection unit 3 and the logic value of the phase reversal detection signal 10 from the input signal phase reversal detection unit 7. In other words, it is determined whether or not the amplitude is within a certain range and the phase inversion is continuously occurring, that is, whether or not the phase inversion is normally detected. The output signal 12, which is its output, is a true / false logical value. Here, the condition is true if such a condition is satisfied, and false if the condition is not satisfied.

(A-2) Description of Operation Next, the operation of the phase inversion detecting device having such a configuration will be described with reference to FIGS.

(A-2-1) First, the operation until the amplitude detection signal 6 is generated from the input signal 1 will be described.

In the discrete Fourier transform unit 2, the given input signal 1 is subjected to Fourier transform, and a level change of the frequency of the phase-inverted signal in the converted frequency band is detected. A complex value x + iy indicating the amplitude and phase for each fixed section is output.

The absolute value calculation unit 4 detects the amplitude r (r = (x ² + y ² ) ^1/2 ), which is the absolute value component, from the complex value x + iy given from the discrete Fourier transform unit 2 and detects the amplitude. The given amplitude r is within a certain range, that is, th1 ≦ r ≦ t.
h2 (th1 and th2 are predetermined values) is detected, and a true logical value is output if it is within the range, and a false logical value is output if it is outside the range. As a result, the amplitude detection signal 6 has a logical value of true in the input signal 1 when the amplitude of the frequency of the phase inversion signal is within a certain range, and false in other cases.

(A-2-2) Next, the operation until the phase inversion detection signal 10 is generated from the input signal 1 and the amplitude detection signal 6 will be described.

The input signal phase inversion detecting section 7 is provided with the complex value x + iy from the discrete Fourier transform section 2 and the logical value of the amplitude detection signal 6 from the input signal amplitude detecting section 3.
The complex value from the discrete Fourier transform unit 2 is provided to a built-in phase estimating unit 8 and a phase inversion detecting unit 9.

Here, when the logical value of the amplitude detection signal 6 is false, the input signal phase inversion detecting section 7 outputs a false logical value. On the other hand, if the logical value of the amplitude detection signal 6 is true, the phase estimating unit 8 estimates the phase of the complex value given to the next section from the discrete Fourier transform unit 2, and the phase inversion detecting unit 9 The estimated phase is compared with the phase actually given from the discrete Fourier transform unit 2 in the next section, and if a phase inversion is detected, a true logical value is detected. Is output. When the amplitude detection signal 6 whose logical value is true is given to the input signal phase inversion detection unit 7 for the first time, the phase estimation unit 8
Then, the parameters necessary for the phase estimation are calculated first, and then the phase estimation is performed.

Here, the method of calculating the parameters required for the phase estimation in the phase estimating section 8 and the method of estimating the phase using the parameters will be described more specifically.

First, a method of calculating parameters required for phase estimation will be described with reference to FIG. In the phase estimating unit 8, the complex value converted for each predetermined interval in the discrete Fourier transform unit 2 is continuously held for three intervals, and the phase difference Δθ between the first interval and the last interval in these three intervals is stored.
Is calculated, and in the first embodiment, the calculated phase difference Δθ is a parameter necessary for phase estimation.

For example, in FIG. 2, three consecutive sections are referred to as section A, section B, and section C, and the complex value from the discrete Fourier transform unit 2 for each section is xA + iy
A, xB + iyB, xC + iyC. It is assumed that the amplitudes of the complex values in each section are equal to each other.
Here, the phases θA and θC of the sections A and C are respectively θA = arctan (yA / xA) and θC = arctan (yC /
xC), and if θC−θA is further calculated,
The phase difference Δθ between the section C and the section A in FIG. 2 can be obtained. Here, θA and θC are respectively xA <0,
When xC <C, π is added.

Next, a method of estimating the phase using the calculated parameter Δθ will be described with reference to FIG.

FIG. 3 shows a state in which a section D immediately before the current section F is shifted from a section D immediately before.
FIG. 5 is an explanatory diagram in the case of estimating the phase of the. Here, assuming that the phase of the section F to be estimated is θ ′, and the phase of the section D two immediately before is θD, the phase θ ′ of the section F to be estimated can be estimated from the calculation result of θD + Δθ. Note that θD is θD
= Arctan (yD / xD). Here, xD and yD are the values of the real part and the imaginary part of the complex value xD + iyD from the discrete Fourier transform unit 2 in the section D, respectively.
When xD <0, π is added to θD in the above equation.

In this way, the phase estimating section 8 calculates the parameters necessary for the phase estimation and estimates the phase, and supplies the estimated phase to the phase inversion detecting section 9.

Subsequently, the phase inversion detecting section 9 compares the phase estimated by the phase estimating section 8 with the phase of the actual complex value provided from the discrete Fourier transform section 2, and these are inverted. The phase inversion is detected when the phase difference is considered to be large. The output becomes true if phase inversion is detected, and becomes false if phase inversion is not detected.

Here, a method of detecting phase inversion will be specifically described. Assuming that the phase of the complex value from the discrete Fourier transform unit 2 is θ and the estimated phase is θ ′, θ−
θ ′ is the difference between the expected phase and the actual phase. That is, unless phase inversion occurs, | θ−θ ′ | ≒
0, on the other hand, if inversion has occurred, | θ−θ ′ |
It takes a value close to.

For this reason, the phase inversion detection method is to determine a certain threshold value th3 (0 <th3 <π) and to set | θ−θ ′ |> t
If h3, the phase inversion is detected, and conversely, | θ−θ ′ |
If <th3, no phase inversion is detected.
Here, as the threshold th3 is closer to 0, the probability of detection in the inverted section is higher, but the probability of erroneous detection due to noise or the like is also higher. Conversely, when the threshold th3 is closer to π, the inversion is smaller. The inversion is detected in the next section instead of the section that has been performed, or the inversion cannot be detected. Therefore, the threshold value th3 needs to be set to an appropriate value according to the system to which the threshold value th3 is applied.

In this manner, in the input signal phase inversion detecting section 7, when the value of the amplitude detection signal 6 is a false logical value, a false logical value is always output, while the value of the amplitude detecting signal 6 is In the case of a true logical value, a detection operation is performed, and a true logical value is output when phase inversion occurs in the phase inversion signal, and a false logical value is output when phase inversion does not occur. . The output is the phase inversion detection signal 10.

(A-2-3) Further, the operation until the output signal 12 is generated from the amplitude detection signal 6 and the phase inversion detection signal 10 will be described.

The amplitude / phase inversion detecting section 11 receives the amplitude detection signal 6 from the input signal amplitude detection section 3 and the phase inversion detection signal 10 from the input signal phase inversion detection section 7, and the amplitude detection signal 6 is provided. When the true value continues for a certain period, and when the phase inversion detection signal 10 has a certain value or more in a certain cycle, a true logical value is output. In this case, a false logical value is output. That is, when the output signal 12 is a true value, the output signal 12 indicates that the input signal 1 has an amplitude within a predetermined range for a certain period, and that a certain number of phase inversions occur in a certain period. Becomes

When the amplitude / phase reversal detecting section 11 indicates that the input signal amplitude detecting section 3 has continuously detected the true state for a certain period (M times), the input / amplitude detecting section 11 keeps detecting the input signal until N times. Even if the signal amplitude detecting unit 3 temporarily detects false, if the signal amplitude detecting unit 3 has a function of a continuous detection protection sequence for continuously detecting true, erroneous detection of the input signal amplitude detecting unit 3 due to noise or the like. Therefore, the erroneous logical value of the output signal 12 is reduced, which is preferable. Here, FIG.
FIG. 8 is an explanatory diagram of an operation of a continuous detection protection sequence when M = 2 and N = 4.

In FIG. 4, when the power is turned on from step 41 in which the operation is stopped, the process goes to step 42 in which the operation is normal. Here, if a true logical value is provided from the input signal phase detector 3 for one section. Go to step 43,
Subsequently, if a true logical value is provided for one section, the process proceeds to step 44 in the continuous detection protection state, and thereafter, if a true logical value is continuously provided, the process remains at step 44. On the other hand, if a false logical value is given to the next section in step 43, the process returns to step 41 in the normal operation state.

Step 4 in the continuous detection protection state
In step 4, when a false logical value for one section is provided, the process proceeds to step 45, and when a false logical value for one section is subsequently provided, the process proceeds to step 46. Step 42 is normal operation state when given
Will return to.

Here, in step 45 or step 46, if a true logical value is given to the next section, the process returns to step 44 in the continuous detection protection state.

Although FIG. 4 shows the case where M = 2 and N = 4, it goes without saying that each value may be a value according to the specifications of the system to which it is applied.

It is preferable that the amplitude / phase inversion detecting section 11 has a function of appropriately setting the values of M and N, since the function can be flexibly applied to the system to be applied.

(A-3) Description of Effect As described above, according to the first embodiment, (1) three consecutive complex values provided from the discrete Fourier transform unit 2 are stored, and these three The phase estimator 8 calculates the phase difference between the first section and the last section, and adds the calculated phase difference to the phase of the section immediately before the section to be estimated, thereby estimating the phase of the estimated section. (2) The phase of the complex value from the discrete Fourier transform unit 2 is compared with the phase estimated from the phase estimating unit 8, and if these have a phase difference of such a degree that inversion seems to have occurred, Since it has the phase inversion detection unit 9 for detecting inversion, it is possible to detect phase inversion regardless of the frequency of the input signal, and even if the frequency is not specified and / or the phase inversion signal has a large frequency error, the phase inversion is performed. Detecting Will be able to

For example, although the first embodiment has been briefly described in the prior art, ITU-T Recommendation G. This is effective for detecting the disabling signal of the echo canceller at 165. G. The disabling signal of the echo canceller at 165 has a frequency of 2100 ± 21H.
z, the amplitude is −31 dB or more and −6 dB or less, and 450
It is a signal whose phase is inverted within a range of 180 ± 25 ° in a period of ± 25 ms.

According to the first embodiment, the presence of the amplitude / phase reversal detecting section 11 makes it possible to detect whether or not the detected phase reversal signal is as specified. Further, if the amplitude / phase inversion detection unit 11 has a function of a continuous detection protection sequence, the logical value of the output signal 12 may be incorrect due to erroneous detection of the input signal amplitude detection unit 3 due to noise or the like. Can be reduced.

(B) Second Embodiment Hereinafter, a second embodiment in which the phase inversion detection device according to the present invention is applied to a phase inversion detection device for detecting the phase inversion of a phase inversion signal will be described.
The embodiment will be described in detail with reference to the drawings.

The phase inversion detection device of the second embodiment has the same configuration as that of the first embodiment, and will be described with reference to FIG. 1. A discrete Fourier transform unit (“DFT” in the figure) 2 An input signal amplitude detection unit 3 having an absolute value detection unit (“ABS” in the figure) 4 and an amplitude detection unit 5; an input signal phase inversion detection unit 7 having a phase estimation unit 8 and a phase inversion detection unit 9; And a phase inversion detection unit 11.

First, the connection correspondence of each component will be described. The input signal 1 is provided to a discrete Fourier transform unit 2, which is connected to an input signal amplitude detector 3 and an input signal phase inversion detector 7. The amplitude detection signal 6 output from the input signal amplitude detection unit 3 is provided to the input signal phase inversion detection unit 7 and the amplitude / phase inversion detection unit 11, whereas the amplitude detection signal 6 is output from the input signal phase inversion detection unit 7. The phase inversion detection signal 10 is output from the amplitude / phase inversion detection unit 11.
Given to. Further, the amplitude / phase inversion detecting section 11 outputs an output signal 12.

Here, the difference from the first embodiment is that the phase estimating unit 8 and the phase inversion detecting unit 9 calculate a parameter necessary for the phase estimation and estimate the phase using the parameter. The method differs from the method of detecting the phase inversion from the estimated phase and the actual phase.

Therefore, hereinafter, the different points will be mainly described, and the description of the same points will be omitted.
Note that the second embodiment will also be described with reference to FIGS. 2 and 3 used in the description of the operation of the first embodiment.

First, a method of calculating parameters required for phase estimation will be described with reference to FIG. In the phase estimating unit 8, the complex value converted for each predetermined interval in the discrete Fourier transforming unit 2 is continuously held for three intervals, and the cosine values cosΔθ and cosine of the phase difference between the first interval and the last interval in these three intervals are obtained. The sine value sinΔθ is calculated, and in the second embodiment, the cosine value of the calculated phase difference cos
Δθ and sine value sinΔθ are parameters necessary for phase estimation.

For example, in FIG. 2, three consecutive sections are referred to as section A, section B, and section C, and a complex value obtained by performing a discrete Fourier transform on each section is xA + iy
A, xB + iyB, xC + iyC. It is assumed that the amplitudes of the complex values in each section are equal to each other.
Here, the cosine value cosΔθ and the sine value sinΔθ of the phase difference between the phases θA and θC in the sections A and C can be calculated from the following equations 1 and 2, respectively. Equation 1: cosΔθ = cos (θC- θA) = cosθC * cosθA + sinθC * sinθA = (xC * xA + yC * yA) / r 2 Equation 2: sinΔθ = sin (θC- θA) = sinθC * cosθA - cosθC * sinθA = can be calculated from (yC * xA-xC * yA ) / r 2.

Next, the calculated parameter cosΔθ
And a method of estimating the phase using sinΔθ will be described with reference to FIG.

FIG. 3 shows a state in which the current section F is shifted from the section D immediately before the current section F to the current section F.
FIG. 5 is an explanatory diagram in the case of estimating the phase of the. Here, section F
The real part of the complex value of is r'cosθ 'and the imaginary part is r'sin
Assuming that θ ′ is the phase of the complex value of the previous section D and that the calculated parameters are cosΔθ and sinΔθ, r′co
sθ ′ and r′sinθ ′ can be calculated from the following equations 3 and 4, respectively. Equation 3: r′cosθ ′ = rcos (θ + Δθ) = rcosθcosΔθ−rsinθsinΔθ = xcosΔθ−ysinΔθ Equation 4: r′sinθ ′ = rsin (θ + Δθ) = rsinθcosΔθ + rcosθ can be calculated from rsinθcosΔθ + rcosθin Δscosθ. Here, x and y are in the section D
Are the values of the real and imaginary parts of the complex value x + iy of the discrete Fourier transform of

In this way, the phase estimating unit 8 calculates the parameters necessary for the phase estimation and estimates the phase, and supplies the estimated phase to the phase inversion detecting unit 9.

Further, a method of detecting phase inversion in the phase inversion detecting section 9 will be specifically described. The complex value from the discrete Fourier transform unit 2 is re ^iθ , the complex value estimated by the phase estimating unit 8 is r′e ^{iθ ′} , and a new complex value f is introduced. Here, each amplitude 'and to note that, f is the following formula 5, and the formula ^{5: f = re iθ + r'e} iθ equal (r = r)' = r {(cosθ + cosθ ') + i (sin θ + sin θ ′)} Further, when | f | ² is calculated in order to obtain the phase difference between re ^iθ and r′e ^{iθ ′} , the following equation 6 is obtained. Equation 6: | f | ² = r ² {(cos θ + cos θ ′) ² + (sin θ + sin θ ′) ² } = r ² {2 + 2 (cos θcos θ ′ + sin θ sin θ ′)} = 2r ² {1 + cos (θ−θ ′)} where θ−θ ′ is the difference between the predicted phase and the actual phase. That is, if phase inversion has not occurred |
θ−θ ′ | ≒ 0, and cos (θ−θ ′) ≒ 1. On the other hand, if inversion has occurred, | θ−θ ′ | takes a value close to π, and cos (θ−θ ′) becomes −1, although it depends on when the inversion occurs in the converted section. It is a value close to.

Therefore, the method of detecting phase inversion requires a certain threshold.
The value th4 (-1 <th4 <1) is determined, and | f |²<2r
²If {1 + th4}, phase inversion is detected, and conversely, |
f | ²> 2r²If {1 + th4}, detect phase inversion
It does not. Here, this threshold th4 is close to 1.
The higher the probability of detection in the inverted section
However, the probability of erroneous detection due to noise and detection accuracy is high.
Conversely, when the threshold value th4 approaches −1,
Is detected in the next section instead of the inverted section of
Or inversion cannot be detected. Therefore, this
The threshold value th4 is set to an appropriate value according to the applied system.
There is a need.

As described above, in the input signal phase inversion detecting section 7, when the value of the amplitude detection signal 6 is a false logical value, a false logical value is always output, while the value of the amplitude detecting signal 6 is When the logical value is true, a detection operation is performed and the input signal 1
When the phase inversion occurs, a true logical value is output, and when the phase inversion does not occur, a false logical value is output. The output is the phase inversion detection signal 10.

As described above, according to the second embodiment,
An effect similar to that of the first embodiment can be obtained.

Further, according to the second embodiment, the process can be performed only by the four arithmetic operations in detecting the phase inversion, so that the operation amount is smaller than the calculation of the arc tangent used in the first embodiment. In addition, the amount of arithmetic processing can be reduced as compared with the first embodiment.

In particular, when processing must be performed in real time as in the case of detection of a disabling signal of an echo canceller, the amount of computation becomes a serious problem.
It is preferable to use the configuration of the second embodiment.

(C) Third Embodiment Hereinafter, a third embodiment in which the phase inversion detecting device according to the present invention is applied to a phase inversion detecting device for detecting a disabled signal will be described in detail with reference to the drawings. .

Here, in the third embodiment, when a disable signal is given as an input signal, that is, a sine wave of a specific frequency of about 2100 Hz band (2100 Hz ± 21 Hz) whose input is sampled at 8 KHz, A method of detecting the disabling signal by a method different from the first and second embodiments when a signal whose phase is inverted at a period of 450 ± 25 ms is provided.

The disabling signal is given by the following equation (8), where r (t) is this signal. Equation 8: r (t) = a (t) sin (ω _C t + θ) a (t): square wave with a period of 900 ± 50 ms ω _C : 2079 Hz * 2π ≦ ω _C ≦ 2121 Hz *
2πθ: Arbitrary rad (C-1) Description of Configuration FIG. 5 is a block diagram illustrating a configuration of the phase inversion detection device according to the first embodiment. In FIG. 5, the phase inversion detecting device includes a band-pass filter (“BPF” in the figure) 51.
, A discrete Fourier transform unit (“DFT” in the figure) 52, an absolute value detecting unit (“ABS” in the figure) 54, and an amplitude detecting unit 55
And an input signal amplitude detection unit 53 having
ltiply ”) 57 and a low-pass filter section (“ LP
F ") 58, a waveform converter (" Threshold "in the figure) 59, and a phase inversion detector 60, and an amplitude / phase inversion detector 61.

First, the connection correspondence between the components will be described. The input signal 50 is provided to a bandpass filter unit 51, which is connected to a discrete Fourier transform unit 52 connected to an input signal amplitude detection unit 53 and an input signal phase inversion detection unit 56. The input signal amplitude detection unit 53 is connected to the input signal phase inversion detection unit 56 and the amplitude / phase inversion detection unit 61, while the input signal phase inversion detection unit 56 is connected to the amplitude / phase inversion detection unit 61. . Further, the amplitude / phase inversion detecting section 11 outputs an output signal 62.

Here, the third embodiment is different from the first and second embodiments.
The configuration differs from the embodiment in that the band-pass filter unit 51 is inserted before the discrete Fourier transform unit 52, and the input signal phase inversion detection unit 56 is connected after the band-pass filter unit 51. , The internal configuration of the input signal phase inversion detection unit 56 is different.

Next, each component of the third embodiment, which is different from the first and second embodiments, will be described. Note that components similar to those of the first and second embodiments will be described only briefly.

The band-pass filter 51 receives the input signal 5
Frequency band 2100 of the disabling signal at 0
It passes only ± 21 Hz.

The discrete Fourier transform unit 52 includes first and second
The third embodiment is the same as the discrete Fourier transform unit 2 of the third embodiment.
1 is provided before the input signal amplitude detector 53 so that the amplitude level of the signal passing through 1 can be detected by the input signal amplitude detector 53.

The input signal amplitude detecting section 53 has an absolute value calculating section 54 and an amplitude detecting section 55 therein, and has an absolute value calculating section 4 and an amplitude detecting section 5 therein. This is the same as the input signal amplitude detector 3.

The input signal phase inversion detecting section 56 has a multiplying section 57, a low-pass filter section 58, a waveform converting section 59, and a phase inversion detecting section 60 therein.
This is for detecting a disabled signal from a predetermined band signal that has passed through the band-pass filter unit 51, based on the logical value of the amplitude detection signal from. Here, when the logical value of the amplitude detection signal is true, the input signal
That is, the detection operation is performed only when the amplitude r is within the predetermined range. The output of the phase inversion detection signal takes a true or false logical value. Here, the detection becomes true if the disabling signal is detected, and false if it is not detected.

The multiplying section 57 includes a band-pass filter section 51
2000 Hz to the 2100 ± 21 Hz signal passed through
Is multiplied by the sine wave signal of 2100 ± 21 Hz as shown in the following equation 9,
The band is separated into a frequency band of 1 Hz (first term) and a frequency band of 4100 ± 21 Hz (second term). Equation 9: r (t) * sin (ωt) = a (t) sin (ω C t + θ) * sin (ωt) = a (t) {cos ((ω C -ω) t + θ) - cos ((ω C + Ω) t + θ)}} / 2 The low-pass filter unit 58 cuts off a portion having a frequency band of 4100 ± 21 Hz of the signal band-separated by the multiplying unit 57 and only a portion having a frequency band of 100 ± 21 Hz. Through. As a result, the output v (t) is the product of a 10 ms sine wave and a 900 ms square wave a (t) (if a disabling signal is given), as shown in Equation 10 below. It will be. Formula 10: v (t) = { a (t) cos ((ω C -ω) t + θ)} /
2 The waveform conversion section 59 applies a certain threshold value (+ th5, -th5) to the signal v (t) from the low-pass filter section 58.
S (t) = 1 and v (t) if v (t) ≧ + th5
If ≦ −th5, s (t) = − 1, −th5 <v (t) <
+ Th5, s (t) is unchanged, square wave s
The waveform is converted to (t).

The phase inversion detecting section 60 monitors the interval of the rising cycle of the square wave supplied from the waveform converting section 59,
A change occurs in the interval, and the change in the interval is 450 ms.
If the detection is made again later, the disabling signal is detected. Here, a true logical value is output if the disabled signal is detected, and a false logical value is output if the disabled signal is not detected. This output is an output when the input signal phase inversion detection unit 56 operates.

The amplitude / phase inversion detecting section 61 is the same as the amplitude / phase inversion detecting section 11 of the first and second embodiments, has an amplitude continuously within a certain range, and
This is to determine whether or not the phase inversion occurs continuously at a cycle of 0 ms, that is, whether or not the phase inversion is normally detected. The output signal 62, which is its output, is a true or false logical value. Here, the condition is true if such a condition is satisfied, and false if the condition is not satisfied.

(C-2) Description of Operation Further, the operation of the phase inversion detecting device having such a configuration will be described focusing on the differences from the first and second embodiments.

In the band-pass filter section 51, the input signal 5
From the signal from which only the frequency band 2100 ± 21 Hz is extracted from 0, its level change is detected by the discrete Fourier transform unit 52, and the complex value x + iy indicating the amplitude and phase of each certain section of the level change is obtained. The input signal amplitude detector 53 outputs a true logical value if the amplitude r of the complex value is within a predetermined range, and outputs a false logical value if the amplitude r is out of the predetermined range.

On the other hand, the signal obtained by extracting only the frequency band 2100 ± 21 Hz from the input signal 50 by the band-pass filter section 51 is given to the input signal phase change detecting section 56, Is given the logical value of the amplitude detection signal from the input signal amplitude detection unit 53.

Here, when the logical value of the amplitude detection signal is false, the input signal phase inversion detecting section 7 outputs a false logical value. On the other hand, when the logical value of the amplitude detection signal is true, the multiplying unit 57, the low-pass filter unit 58, the waveform conversion unit 59, and the phase inversion detection unit 60 detect the disabled ringing signal described below. Is performed, a true signal is output if the disabling signal is detected, and a phase inversion detection signal indicating a false logical value is output if the disabled signal is not detected.

The multiplication unit 57 multiplies the sine wave signal of 2000 Hz by the signal from the band-pass filter unit 51,
As a result, as shown in Equation 9, the signal from the band-pass filter unit 51 is separated into a frequency band of 100 ± 21 Hz (first term) and a frequency band of 4100 ± 21 Hz (second term). Is done.

In the low-pass filter section 58, the product section 57
A portion having a frequency band of 4100 ± 21 Hz is cut off in the signal separated in the band, and only a portion having a frequency band of 100 ± 21 Hz passes. As a result, the output v (t) becomes 10 ms as shown in the above equation (10).
And a square wave a (t) having a period of 900 ms.

If the input signal is not a disabling signal, the output v (t) has a period of 900 ms.
A signal component having a continuous phase with a period of about 10 ms is not detected. However, if the signal is a disabling signal, the period is 900 ms.
A signal component of a degree is included, and as a result, the phase shifts by about π every 450 ms, which is a half cycle of the disabling signal.

Therefore, in order to detect whether or not a phase shift has occurred, the waveform converter 59 applies a certain threshold (+) to the signal v (t) from the low-pass filter 58.
th5, −th5), s (t) = 1 if v (t) ≧ + th5, s (t) = −, − if v (t) ≦ −th5
If th5 <v (t) <+ th5, the waveform is converted to a square wave s (t) that s (t) does not change.

Here, if the phase inversion is not performed (not the disabled signal), the rising cycle of the square wave is always constant. Conversely, if the phase inversion is performed (if it is a disabled signal), a deviation occurs in the rising cycle of the square wave.

Therefore, the phase inversion detecting section 60 monitors the interval of the rising cycle of the square wave, and changes the interval. If the change of the interval is detected again after 450 ms, the disabling ring signal is detected. Will be done. Note that even if the phase inversion detection unit 60 monitors the interval of the falling cycle of this square wave,
Needless to say, similar detection can be performed.

As described above, in the input signal phase inversion detecting section 56, when the value of the amplitude detection signal is a false logical value, a false logical value is always output, while the value of the amplitude detecting signal is true. In the case of the logical value, the detection operation of the disable signal is performed. If the disable signal is detected, a true signal is detected, and if not, a phase inversion detection signal indicating a false logical value is output.

The amplitude / phase inversion detecting section 61 receives the amplitude detection signal from the input signal amplitude detection section 53 and the phase inversion detection signal from the input signal phase inversion detection section 56, and outputs the amplitude detection signal for a certain period. If the true value continues,
In addition, when the phase inversion detection signal takes a true value in a cycle of 900 ms, an output signal 62 indicating a true logical value is output. Otherwise, an output signal 62 indicating a false logical value is output.

Note that the amplitude / phase inversion detecting section 61 also
Similarly to the amplitude / phase inversion detecting unit 11 of the second embodiment, if the input signal amplitude detecting unit 53 has the function of the continuous detection protection sequence, the output signal 12 Is less likely to cause a mistake in the logical value of.

(C-3) Description of Effect As described above, according to the third embodiment, (1) the frequency band 2100 of the disabling signal is obtained from the input signal 50.
Bandpass filter section 51 that passes only ± 21 Hz
And (2) 210 that has passed through the band-pass filter unit 51
A signal of 0 ± 21 Hz is multiplied by a sine wave signal of 2000 Hz, and as a result, as shown in the following equation 9, 10
A part having a frequency of about 0 Hz and the second term 4100H
a product section 57 for generating a signal consisting of a portion having a frequency of about z, and (3) a section having a frequency of about 4100 Hz of the second term is cut off from the signal given from the product section 57, A low-pass filter section 58 that passes only a portion having a frequency of about 100 Hz of item 1;
(4) A certain threshold value is provided for the signal from the low-pass filter unit 58, and the given signal is shaped into a square wave, and (5) the square wave Since the interval of the rising cycle is monitored and a change occurs in the interval, and when the change in the interval is detected again after about 450 ms, the phase inversion detecting unit 60 for detecting the disabling signal is provided. Even if the error is large, the phase inversion can be detected by appropriately setting the width of about 450 ms for detecting the change in the rising cycle interval of the square wave.

Further, according to the third embodiment, the provision of the amplitude / phase inversion detecting section 61 makes it possible to detect whether or not the detected disabling signal is as specified. Further, if the amplitude / phase inversion detecting unit 61 has a function of a continuous detection protection sequence,
It is possible to reduce the possibility that the logical value of the output signal 12 is erroneous due to erroneous detection of the input signal amplitude detector 3 due to noise or the like.

Further, according to the third embodiment, the processing can be performed only by the addition and multiplication operations in the detection of the phase inversion, so that the calculation amount is smaller than the calculation of the arc tangent used in the first embodiment. And the amount of arithmetic processing can be smaller than in the first embodiment, as in the second embodiment.

In particular, in the case of an input signal sampled at 8 KHz, if a signal having a frequency of 2000 Hz is multiplied by the input signal, frequency multiplication is performed simply by multiplying by a simple constant value of -1, 0 and 1. Will be able to do.

(D) Other Embodiments In the third embodiment, the case where the present invention is applied to a method for detecting a disabling signal has been described. Recommendation V.
The same applies to those detecting an answer tone indicated by reference numeral 25, detecting an identification signal between voice and a fax / modem control signal, or detecting n-phase PSK (Phase Shift Keying). Of course, it goes without saying that the present invention can be similarly applied to the detection of a phase inversion signal in which the phase is generally irregularly inverted.

In each of the above embodiments, the input signal phase inversion detecting section detects the phase inversion only when a true logical value is given from the input signal amplitude detecting section. Regardless of the logical value from the amplitude detector (ie, without providing the input signal phase amplitude detector), the input signal phase inversion detector may detect the phase inversion. In this case, the amplitude
The phase inversion detection unit is also eliminated from the components.

Further, in the first and second embodiments, after calculating the parameter for which the phase is to be estimated in the phase determination unit 8, the phase is always estimated using this parameter. After the calculation, within a predetermined period during which the phase of the input signal is not inverted, the parameter for phase estimation may be recalculated and updated to the recalculated parameter.

Furthermore, in the first and second embodiments, the discrete Fourier transform unit 2 performs a Fourier transform of the input signal 1 in a certain section, so that a complex value indicating an amplitude and a phase in a certain section is used. However, if the discrete Fourier transform unit 2 instantaneously processes and outputs a complex value, a complex value is periodically output at a certain point in a certain section.

In the first and second embodiments, the phase estimating unit 8 stores complex values of three consecutive sections and calculates a phase difference from the first and last sections of the three sections. Although the phase is estimated by adding the calculated phase difference to the phase of the section immediately before the section to be estimated, as described above, unless the processing section of the discrete Fourier transform unit 2 is assumed, A phase difference between two phases of the input signal detected in the past is calculated, and the calculated phase difference is added to a phase at a time point before the two time points from the current time to estimate the current phase. Will do.

Further, in the third embodiment, a certain threshold value (+ th5, -th5) is provided for the signal from the low-pass filter unit 58 in the waveform conversion unit 59, and v
If (t) ≧ + th5, s (t) = 1, v (t) ≦ −th5
If s (t) = − 1, −th5 <v (t) <+ th5, s (t) is unchanged, and the waveform is converted to a square wave s (t). Without limiting the value to the same value, or without providing two thresholds, a point in time when the level of the input signal exceeds or falls below a predetermined value is detected. It may output a pulse signal having a logical value.

[0102]

As described above, according to the first aspect of the present invention,
In a phase inversion detection device that detects a phase inversion in a signal whose phase is inverted, a phase of a current input signal is estimated based on phase information of an input signal detected in the past, and the estimated phase and a current detection phase are calculated. When there is a phase difference within a predetermined range, since the phase inversion detecting means for detecting the phase inversion is provided, the phase inversion can be detected regardless of the frequency of the input signal, the frequency is not specified, and / or the frequency error Is large, the phase inversion can be detected.

According to the second aspect of the present invention, there is provided a phase inversion detecting device for detecting phase inversion in a signal whose phase is inverted, wherein the level of the input signal exceeds a first predetermined value, and / or Since there is a phase inversion detecting means for detecting a time point when the time falls below a second predetermined value smaller than the first predetermined value and detecting a phase inversion when an interval between the detected time points is out of a predetermined range, As in the first aspect of the present invention, phase inversion can be detected irrespective of the frequency of the input signal, and even if the frequency is not specified and / or the phase inversion signal has a large frequency error, the phase inversion is detected. Will be able to

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a phase inversion detection device according to a first embodiment.

FIG. 2 is an explanatory diagram for calculating parameters necessary for phase estimation in the first embodiment.

FIG. 3 is an explanatory diagram for calculating a phase to be estimated using parameters in the first embodiment.

FIG. 4 is a functional explanatory diagram of a continuous detection protection sequence in the first embodiment.

FIG. 5 is a block diagram illustrating a configuration of a phase inversion detection device according to a third embodiment.

[Explanation of symbols]

2. Discrete Fourier transform unit, 8: Phase estimation unit, 9: Phase inversion detection unit.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Koichi Kihara 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. F-term (reference) 5K046 AA01 HH13 HH14 HH37 HH72

Claims (17)

[Claims] 1. A phase inversion detecting apparatus for detecting phase inversion in a signal whose phase is inverted, comprising: estimating a current phase of an input signal based on phase information of an input signal detected in the past; A phase inversion detecting means for detecting phase inversion when the detected phase has a phase difference within a predetermined range. 2. An apparatus according to claim 1, further comprising an amplitude detector for detecting whether an amplitude of the input signal is within a predetermined range, wherein said phase inversion detector detects an amplitude outside said predetermined range. 2. The phase inversion detecting apparatus according to claim 1, wherein the phase inversion detecting operation is stopped. 3. When the amplitude detecting means continuously detects an amplitude within a predetermined range, and when the phase inversion detecting means detects the phase inversion according to a predetermined rule, the phase inversion is normally detected. 3. The phase inversion detecting apparatus according to claim 2, further comprising an amplitude / phase inversion detecting means for judging the phase inversion. 4. The amplitude / phase inversion detecting means, wherein the amplitude detecting means detects an amplitude within a predetermined range of a first predetermined time or more, and thereafter, an amplitude outside a predetermined range within a second predetermined time. Is detected, and if the amplitude within the predetermined range is detected again, the fact that the amplitude outside the predetermined range is detected is ignored, and the amplitude within the predetermined range is continuously detected. The phase inversion detecting device according to claim 3, wherein 5. The phase inversion detecting means calculates an estimation phase difference which is a phase difference between two phases of the input signal detected in the past, and calculates a phase difference between the current time and the time immediately before these two time points. By adding this estimation phase difference to the phase, a phase estimator for estimating the current phase is compared with the phase estimated by the phase estimator and the detected phase of the input signal at the current time. 5. A phase inversion detecting section for detecting whether or not the phase difference has a phase difference within a predetermined range, and detecting a phase inversion when the phase difference has a phase difference within a predetermined range. The phase inversion detecting device according to any one of the above. 6. The phase inversion detecting device according to claim 5, wherein the phase estimating unit updates the estimation phase difference within a predetermined period during which the phase is not inverted. 7. A conversion means for converting an input signal into a value represented by a complex number in a predetermined cycle, and providing the complex value sequence converted by the conversion means to the phase inversion detection means and / or the amplitude detection means. The phase inversion detecting device according to claim 1, wherein: 8. The phase inversion detecting means calculates the phase at each time point as arctan (imaginary part / real part) from a real part and an imaginary part of the complex value converted by the converting means. The phase inversion detecting device according to claim 7, wherein 9. The phase inversion detecting means calculates the estimated value of the current phase by the four arithmetic operations from the real part and the imaginary part of the complex value at the two past times converted by the converting means. The phase inversion detecting device according to claim 7, wherein 10. A phase inversion detecting device for detecting phase inversion in a signal whose phase is inverted, wherein the level of the input signal exceeds a first predetermined value and / or a signal having a level smaller than the first predetermined value. 2. A phase inversion detecting device, comprising: a phase inversion detecting means for detecting a time point when the time falls below a predetermined value of 2 and detecting a phase inversion when an interval between the detected time points is outside a predetermined range. 11. An amplitude detecting means for detecting whether or not an amplitude of an input signal is within a predetermined range, wherein said phase inversion detecting means is provided when said amplitude detecting means detects an amplitude outside the predetermined range. The phase inversion detecting apparatus according to claim 10, wherein the detecting operation of the phase inversion is stopped. 12. When the amplitude detecting means continuously detects an amplitude within a predetermined range, and when the phase inversion detecting means detects the phase inversion according to a predetermined rule, the phase inversion is normally detected. 12. The phase inversion detecting apparatus according to claim 11, further comprising an amplitude / phase inversion detecting means for judging the phase inversion. 13. The amplitude / phase inversion detecting means, wherein the amplitude detecting means detects an amplitude within a predetermined range of a first predetermined time or more, and thereafter, an amplitude outside a predetermined range within a second predetermined time. Is detected, and if the amplitude within the predetermined range is detected again, the fact that the amplitude outside the predetermined range is detected is ignored, and the amplitude within the predetermined range is continuously detected. The phase inversion detecting device according to claim 12, wherein 14. The phase inversion detecting apparatus according to claim 10, further comprising a band pass filter means for passing only a predetermined frequency band of the input signal and applying the input signal to said phase inversion detecting means. 15. The phase inversion detecting means detects a point in time when the level of the input signal exceeds a first predetermined value and / or a point in time when the level falls below a second predetermined value smaller than the first predetermined value. A pulse signal output unit that outputs a pulse signal having a different logical value before and after each of the detected time points; and an interval of the same logical value of the pulse signal output by the pulse signal output unit is an interval outside a predetermined range. The phase inversion detecting device according to claim 10, further comprising: a phase inversion detecting unit that detects a phase inversion. 16. The phase inversion detecting means includes a band conversion unit that converts a frequency band of an input signal into a frequency band lower than the frequency band and provides the frequency band to the pulse signal output unit. 16. The phase inversion detecting device according to 15. 17. The band conversion unit multiplies an input signal by a wave having a predetermined frequency, thereby changing a frequency band of the input signal to a frequency band lower than the predetermined frequency band and a frequency band lower than the predetermined frequency band. 17. The phase inversion detection device according to claim 16, further comprising: a band separation unit configured to separate the high frequency band into a high frequency band; and a low-pass filter unit configured to remove a high frequency band part separated by the band separation unit.