JPH0353174A - Selective level meter - Google Patents

Abstract

PURPOSE:To reduce the circuit scale by accumulating two waves having 90 deg. phase difference and operating the sum of them after squaring. CONSTITUTION:An analog input signal 1 passes an A/D converter 2 to become a digital signal 3, and the product between the signal 3 and the output of a variable digital sine wave oscillator 4 is operated by a digital multiplier 5, and an output 6 of the multiplier 5 is inputted to a 90 deg. phase difference branching filter 7. The output 6 is branched to two waves having 90 deg. phase difference, and outputs 8 and 9 of the branching filter 7 are inputted to accumulators 10 and 11 respectively and a accumulated. Outputs 12 and 13 of accumulators 10 and 11 are squared by squares 14 and 15 and are inputted to a digital adder 18 as outputs 16 and 17. The sum of outputs 16 and 17 is operated by the adder 18, and an output 19 of the adder 18 is the selective level output. Since the period of accumulation is extended to raise the selectivity, a variable band pass filter is unnecessary and the circuit scale is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a selective repel meter, and more particularly to a selective repel meter using digital signal processing.

[Conventional technology]

FIG. 4 is a diagram showing an example of a conventional selection level meter.

The input analog input signal l is used to extract a certain portion of the signal in a necessary band by a band pass filter 6l having a variable pass band.

The output of the pandobus noise filter 6l is detected by a wave detector 62, and the output is measured by a level meter 63, thereby measuring the level of a certain frequency of the input signal.

[Problem to be solved by the invention]

The above-mentioned conventional selective repellometer uses a bandpass filter with a variable pass band to select a certain portion of the signal, and therefore has the disadvantage that its selection characteristics differ depending on the band to be measured.

Furthermore, in order to sharpen the selection characteristics, it is necessary to increase the scale of the variable bandpass filter, which has the disadvantage of increasing the circuit scale.

[Means to solve the problem]

The selection level meter of the first invention includes a multiplier that multiplies an input signal and the output of a variable sine wave oscillator, and a 90-degree phase difference that divides the output of this multiplier into two waves with a 90-degree phase difference. a waveform generator, first and second cumulative adders that cumulatively add the outputs of the 90-degree phase difference waveform, and first and second cumulative adders that square the outputs of the first and second cumulative adders, respectively. and an adder that takes the sum of the output of the first squarer and the output of the second squarer, and the output of the adder is used as a selection level output.

1. The selection level meter of the second invention has an input signal of 9
A 90 degree phase difference wave splitter that splits the wave into two waves with a phase difference of 0 degrees,
first and second multipliers that multiply the output of the variable sine wave oscillator and the output of the 90-degree phase difference transducer, and a second multiplier that cumulatively adds the outputs of the first and second multipliers, respectively. 1
, a second cumulative adder, first and second squarers that square the outputs of the first and second xa′ adders, respectively, and the output of the first squarer and the second squarer. The present invention is characterized in that it includes an adder that takes the sum of the outputs of the adders, and the output of this adder is used as a selection level output.

Furthermore, the selective level meter of the third invention includes a 90 degree phase difference duplexer that divides the output of the variable sine wave oscillator into two waves with a phase difference of 90 degrees, and an input signal and an output of the 90 degree phase difference duplexer. first and second accumulators that cumulatively add the outputs of the first and second integrator, respectively; first and second squarers that square the outputs of the cumulative adders, and an adder that sums the outputs of the first squarer and the second squarer; It is characterized in that the output is a selection level output.

〔Example〕

Next, the present invention will be explained with reference to FIGS. 1 to 3.

FIGS. 1, 2, and 3 are block diagrams showing embodiments of the first, second, and third inventions, respectively, and the same structural elements are denoted by the same reference numerals.

As shown in FIG. 1, an embodiment of the first invention includes an analog-digital converter (hereinafter referred to as A/D) 2 that converts an analog input signal 1 into a digital signal, a digital signal 3 output from the A/D 2, and a variable digital converter 2 that converts an analog input signal 1 into a digital signal. Sine wave oscillator (hereinafter referred to as SIN),
a digital multiplier 5 which takes the product of the output of i, a 90 degree phase difference duplexer 7 which divides the output 6 of the digital multiplier 5 into two waves with a 90 degree phase difference, and a 90 degree phase difference duplexer 7. Accumulator (hereinafter referred to as Σ) 1 that cumulatively adds the outputs 8 and 9 of
0.11, a squarer 14.15 that squares the outputs 12.13 of Σ10 and 11, respectively, and a digital adder l8 that takes the sum of the outputs 16.17 of the squarers 14 and l5,
The output l9 of the digital adder l8 is used as a selection level output.

Now, consider the analog input signal number 1 as x (t) = A cos (ωt 10) + B cos (a/
Let us consider measuring the precept of this angular frequency ω, expressed as t+θ (1). S IN4 output a (t)
Then, a(t)=sin(ωt)
...(2) (1), (2) formula, a(t) x(t)=sin (ωt) (Acos
(ωt+θ)+Bcos(mt+θri)=sin(ω
t) (A cos (ωt) cos θ−A sin (ωt) s
inθ+Bcos(/t)cosθ'−B sin (
c/ t) sin θ′}= A s in (ωt
) cos (ωt) cosθ−A sin”(ωt
) sin θ+B sin (ωt) cos (ω
't) cosθ'-B sin (ωt) si
n (ω' t) sinθ'l
1. +-As+n(2ωt-θ)--A
stnθ42 1 1. + One Acos
(2ωt+θ) −−Astn(2ωt−θ)44 1. +-Bs1n ((ω10ωt+θ') 4 l. −ωrit−θ′} 4 1 , +−Bsln((ω+ω/)1+θ′}4 l . −−Bsrn{(ω+ωrit+θ′} 4 l . −−Bs+n{(ω1(,)rit+a ') 4 l. 90
Dividing into two waves X(t) and Y(t) of degree, we get 2 and l , +-B szn ((ω-QJ') t10'+Z+
-) 42 + -! − B s in (((lJ+GJrit+
θ'+z+-142 1. --Bs+n((ω+ω')t-θ'+z+-)42 1. -Bs1n((ω-ωrit1θ'+z+->42 + -!- B s in { (ω-ωrit1θ'+
z+-}42 (5)

Here, (4). By cumulatively adding equation (5), ΣX (t)
= − − A s1n (θ+2)2 (6) l. Σy(t)=-one person stn (θ+Z 11) 22 11 earth Acos (θ+Z) 2 (7). By squaring this, we get {ΣX(t})” = −!− A” sin” (θ
+Z) 4 ・・・・・・(8) {ΣY(t) )Tax=2cos per person” (θ+Z)
...(9)4 Therefore, the sum of equations (8) and (9) is l. {ΣX(t)F + (ΣY(t)F=-A” stn
"(θ+Z)4 10 and A"COS" (θ+Z)=A244...(lO), and the amplitude value of the precept of the angular frequency ω is obtained.

Here, the selectivity consists in reducing a certain portion of the periodic functions in equations (4) and (5) by /J%, so high selectivity can be obtained by performing cumulative Calorie calculation over a long period of time.

Next, an embodiment of the second invention, as shown in FIG.
The digital signal 3 output from D2 is converted into two waves 28. with a phase difference of 90t. 90 degree phase difference splitter 27 which splits into 29, and 8
Output 26 of IN4 and output 28 of 90 degree phase difference converter 27
, 29, a digital multiplier 25
, 35 and the output 30.3 of the digital multiplier 25.35.
Σ10,11 that cumulatively add 1, and Σ10,1
1 output 32. squarer 14 that squares 33,
l5 and a digital adder l8 that takes the sum of the output 36.37 of the squarer 14.15.
The output l9 of is used as the selection level output.

Let us now consider expressing the analog input signal l by x (t) in the above equation Q) and measuring a certain portion of this angular frequency ω. When input signal 3 is divided into two waves X'(t) and
) = Acos (ωt+θ+Z) + B co
s (ω't+θ'+Z)-(12)=A sin(ω
t+θ+Z)+Bsin(cc+'t+θ'+Z)
−(13). Here, the output of SIN24 is b(t>
Then, b (t) = sin (ωt)
・--- --- (14) (12
)． (14) Formula b (t) X'(t)= sin (ωt) (A
cos (ωt 10 + Z) + B cos (ω't
+θ'+z))=Asin(ωt)(cos(ωt)c
osθcos Z- cos (ωt) sinθsi
nZ-sin(ωt) cosθsinZ-sin(
ωt) sinθcosZ}+Bsin(ωt)(co
s(ω't) cosθ'cosZ- cos(ω't
) sinθ'sinZl , =-Astn (2ωt) cosθcos Z2 l . --Asln(2ωt) sinO sinZ2 l + -Acos (2ωt) sinθcos Z2 l . -4--Bstn((ω+ωrit) cosθ'co
sZ2 l , +-Bs1n{(cc+7ω')t}cosθ' co
s Z2 d. −1Bs1n((ω+ωrit) sinθ'sinZ2 l . --Bsxn((ω−ωrit) sinθ'sinZ2 1 − − B cos ((ω−(,Irit) co
sθ'sinZ2 l -l- 1Bcos((ω+ωrit)cosl'sin
Z2 l --BCOS ((ω-GJ') t }sinθ'c
osZ2 l +-a cos { (ω-}-ωrit } sinθ
' cos Z - (15)2 If we perform cumulative addition here, the term of the periodic function becomes 0, so -sin ((Al' t) cosθ' sinZ-
sin(ω't) sinθ'cosZ1 . = −A s 1n (2ωt) cosθco
s Z2 l. --Astn(2ωt) sinθsinZ2 - Asin2(ωt)cosθsinZ-Asin2
(ωt) sinθcos Z1 + BSIn{((jJ+(IJ')t)Cogθ'
cosZ2 10-! -B sin {(ω-ωrit}cosθ'co
sZ2 --! -B sin ((ω+ω')t } sinE
l' sinZ2 --! -Bsin((ω-ω')t)sinθ'sin
Z2 1 --Bcos((ω-ωrit) cosθ'sinZ
2 1 + − B cos ((GJ+GJ') t)
cosθ'sinZ2 1 Bcos((ω-ωrit)sinθ' cos Z2 1 +-l-BCoS{(ω+ωrit)sinθ'cosZ
t ='-Asin(2ωt)cosθcos Z2 -±Asin(2ωt)sinθsinZ2-Asin" (ωt) (cosθsjnZ+sin
! l cosZ)-'A(1-cos(2ωt)}(c
osθsinZ+sinθcosZ)2 1. =--Astn(Z+θ) 2 (l6).

Square this and get {Σb(t) X'(t) }” =-A”s+n”
(Z+θ)4 ・・・・・・(17) Similarly, (13) + (14), Σb(t)X”(t)=−Acos(Z+θ)2 ・・・・・・(18) becomes.

Square this and get {Σb(gx “(t) }” = − A” cos
2(Z+θ)4...(l9). Therefore, the sum of equations (17) and (19) is {Σb
(t) X'(t) }" + {Σb(t)x"(
t))'' (20) The amplitude value of the component of the angular frequency ω is obtained.

Here, selectivity consists in reducing a certain portion of the periodic function of equation (15), so high selectivity can be obtained by performing cumulative addition over a long period of time.

Next, an embodiment of the third invention, as shown in FIG.
A 90 degree phase difference duplexer 47 that divides the output of N4 into two waves 48 and 49 with a phase difference of 90 degrees, and a digital signal 3 of the output of A/D2 and the outputs 48 and 4 of the 90 degree phase difference duplexer 47.
Digital multiplier 45 which takes each product with 9. 5
5, and a digital multiplier 45. 55 output 50.51
Σ10, II and Σ10, 11 that cumulatively add
Squarers 14 and l5 square the outputs 52 and 53i, respectively.
and the output 56 of the squarer 14.15. 57, and the output l9 of the digital adder 18 is used as a selection level output.

Now, let us consider that the analog input signal l is represented by x (t) in the above equation (1), and a certain portion of this angular frequency ω is measured.

Let the output of SIN4 be a (t) in the above equation (2). This signal (1) is input to the 90 degree phase difference converter 47.
a'(t) = sin(ωt+θ'')...C
23) Two waves are obtained. From equations (1) and (Z3), a'f
t) x(t)=sin(ωt+θ”) (Acos(
ωt+θ) 1 Bcos(ω′t+θ′)}=(sin(
ωt) cosθ”+cos (ωt) sinθ〃}-
(A cos (ωt) cos θ−A sin (ωt) sin
θ+acos(ω't) cosθ−Bsin(ω't
) sinθ′}=Acos(ωt) sin(ωt)
cosθ'/cosθ−Asin2(ωt) cos
θ“sinθ+Bsin(ωt) cosθ”CoS(
GJ't) cosθ'-Bsin(ωt) cosθ
“sin(ω't) sinθ+Acos” (ωt)
sin θ' cos θ one person sin(ωt) cos(ω
t) sin θ “sin θ + BCOS (ωt) cos
(ω't) sinθ'cosθ'-Bcos(ω
t) sinθ"sin(ω't)sino'...
...(25) If cumulative addition is performed here, the term for the number of circumferences M becomes O, so the following is obtained.

By squaring this and similarly using equations (1) and (24), Σa"(t) x (t)=cos(cc+t+θ"
) {A cos (ωt+0) (28).

By squaring this, we get: Therefore, the sum of equations (27) and (29) is (Σa
'(t) x(t)p+ (Σa"(t) x(t)
)"4 Then, the amplitude value of the component of angular frequency ω is obtained.

Here, the selectivity lies in reducing the predetermined value of the periodic function in formula C25) by /J%, so high selectivity can be obtained by performing cumulative addition over a long period of time.

〔Effect of the invention〕

As explained above, according to the present invention, a variable sine wave oscillator, a 90 degree phase demultiplexer, and a multiplier are provided, and after cumulatively adding two waves with a phase difference of 90 degrees, and then squaring each wave, By taking the sum υ, the level of the input signal can be obtained. At this time, selectivity can be increased by lengthening the cumulative addition period.

Therefore, the pandonograph 7 filter with a variable pass band used in the conventional selection level meter is not required, so that the selectivity can be kept constant and the circuit size can be reduced.

[Brief explanation of drawings]

1, 2, and 3 are block diagrams showing one embodiment of the first, second, and third inventions, respectively, and FIG. 4 is a block diagram showing an example of a conventional selection level meter. be. l...Analog input signal, 2...Analog-digital converter (A/D), 3...Digital signal, 4...Variable digital sine wave oscillator (SIN), 5, 25, 35, 45.55...
・Digital multiplier, 7.27.47...90
degree phase difference wave generator, 10. 11... Accumulative adder (Σ), 14.15... Square multiplier, 18...
...Digital adder.

Claims (3)

[Claims] (1) A multiplier that multiplies the input signal and the output of the variable sine wave oscillator, a 90 degree phase difference splitter that splits the output of this multiplier into two waves with a 90 degree phase difference, and this 90 degree phase difference splitter. first and second cumulative adders that cumulatively add the outputs of the phase difference waveformers, first and second squarers that square the outputs of the first and second cumulative adders, respectively; an adder that calculates the sum of the output of the first squarer and the output of the second squarer,
A selection level meter characterized in that the output of this adder is used as a selection level output. (2) 90 to split the input signal into two waves with a phase difference of 90 degrees
the output of the variable sine wave oscillator and the
first and second multipliers that take respective products with the outputs of the degree-phase difference modulator; and first and second cumulative adders that cumulatively add the outputs of the first and second multipliers, respectively. , this first,
The first and second squares each square the output of the second cumulative adder.
and an adder that takes the sum of the output of the first squarer and the output of the second squarer, and the output of the adder is used as a selection level output. meter. (3) a 90-degree phase difference splitter that splits the output of the variable sine wave oscillator into two waves with a 90-degree phase difference;
first and second integrators that take respective products with the output of the degree-phase difference waveform generator; and first and second accumulators that cumulatively add the outputs of the first and second integrator, respectively. , this first,
The first and second squares each square the output of the second cumulative adder.
and an adder that takes the sum of the output of the first squarer and the output of the second squarer, and the output of the adder is used as a selection level output. meter.