JPS5947857A - System for inserting additional circuit in stereo modulator and demodulator - Google Patents

Abstract

PURPOSE:To reduce noise of a sum signal or a difference signal at a low frequency stage, by inserting an additional circuit such as noise reduction circuit to either a sum signal line or a difference signal line between a matrix circuit and a de-matrix circuit. CONSTITUTION:The matrix circuit M receives left and right signals L, R and outputs the sum signal L+R and the difference signal L-R. The de-matrix circuit DM receives the signals L+R and L-R, and outputs individually the signals L and R. The additional circuit U0 such as noise reduction circuit is inserted to either line between the circuits M and DM. The signals L, R are switched at switching circuits U1, U2 and superimposed, and outputted as a carrier suppression AM modulation signal forming a composite signal for main carrier modulation. In this case, the noise in the signal L-R at the low frequency stage is reduced with the circuit U0.

Description

[Detailed Description of the Invention] The present invention provides a difference signal (L Ii) size, 1 signal (L + IO noise reduction circuit etc. JtyS times r1'
This relates to the one circuit insertion method where all J is inserted.

A conventional stereo modulator/demodulator will be explained using FIG. 1 as an example of an AM-FM switching stereo modulator. Figure 1 Neutral signal (IH2+ is the left signal (1st
Audio signal) L upper right 1 total C i (2+'+ 2 audio signal) R input terminal, U, U2υ, 1st, i (G 2 switching circuit, LPF, LPF2 is 1.11!2
(3) is a low-pass filter, U3 is a superimposed filter, and (3) is an output filter.
; IA child, (711 (51 is the input terminal of the subcarrier f8. Then, when the left signal and the right signal R are respectively input to the input terminal (11 (2), the left signal and the right signal R are i-l''; subcarrier f in the I switching circuit U and the second switching 1I-1l path U2
6 and the 10th pass filter LPF
, and the output J end of the 20th bus filter LPF2 are provided with the L-1-(L) D88 signal and the R+(R
) DIIB signals appear respectively. Next, these two signals are combined in a superimposed device U-1 and sent from an output terminal (3) to an ifj combination for main carrier modulation I-4-R+ (+- to -
R) +1! I11 is output. Here this? 4 Go A; (L-R)D in No. 3! I11 is carrier wave suppression A
The M modulation signal is indexed as a sub signal, while the sum signal ■74-R
is indexed as Lord No. 115. Switching type stereo modulators (same as decoupler, , No. 20 - Bass filter LPF, , right signal R
is separately fF2F2 transmission suppression submodulation, and then superimposed unit U
3, the main signal (R) and the sub signal (L") D
SII, so the stereo modulator contains the sum signal (
L-1-R) +7- and difference signal (TR) signal lines do not exist.

By the way, the transmitting side still needs to improve 8/N in each of the main signal or sub signal.
:I:, -, and at the stage of this low frequency (voice) No. 111, there is a J7''J case in which it is possible to reduce the noise of the difference signal by sum1□1dno'r:'i.

However, in the conventional stereo modulator, noise reduction must be carried out because there is no path between the signal line and the line size, ', T&-]-difference A11j (lIl) in the device. However, there was a problem in that it was not possible to insert a corresponding circuit.This kind of inter-type) point is only applicable to the above-mentioned Suge 1/O-Fu-y+.
The same is true for the FM-FM stereo modulator/demodulator.r'-0
The purpose of the present invention is to overcome the conventional problems.

This invention will be described below based on the drawings - Crt! i', clarify.

Figures 1 to 3 show a 2R51F Sb applied to this invention's S-R notching type stereo converter W''J.

In addition, in each figure following Figure 2, the previous nu: 71'! 1
Items that are the same or equivalent to the circuit assembly shown in the figure are shown and weighted in the same manner as above. The explanation given will be omitted.

To explain the formation of the neck, the neutral number U4 in Figure 2 is I1.
This is a circuit insertion unit for the left signal and the right (
Fj is introduced separately, and the sum of the right signal is ``1'' to Shima 1i.
No. 1. A matrix circuit M that separately outputs 1R and a difference signal LR, a dematrix circuit DM that outputs a left signal 1 and a right signal R separately, and a dematrix circuit DM that outputs a left signal R and a right signal R separately. It is comprised of an auxiliary circuit Uo such as a noise reduction circuit interposed on either the sum signal line or the difference signal line between the matrix circuit M and the dematrix circuit DM. Incidentally, as an accessory circuit, in addition to the noise reduction circuit, a compressor, an expander, etc. having a noise reduction function are also applied. Then connect the attached circuit insertion unit (such as this) to the input terminal (1)
A system is adopted in which the left 4' connected to the signal (+2) is arranged in parallel with the line (2) and the right signal R, that is, in the front stage of the first and second switching circuits U and U2.

FIG. 3 shows the 17.1ζ generation of the above matrix circuit M M, which includes three in-phase ancivers MP, Alt, lIl.
, AMI14, one inverting amplifier AMP3, and output resistors r, ~r4 connected to these 1) a;/amps, the internal circuit is I'f'? has been completed. Each amplifier AMP,
-AMP4 tJ, its amplification factor is 1, except for the in-phase technique and the inverted Haruno, -Example and 1. Tezono 1 It has a value of "1". (1) a is the output terminal of Washin-F I-I-H; (2) a is the output terminal of the difference signal L-R.

On the other hand, Fig. 4 is a hoax) l) Kusu lj: jl path I to 1 (1'' does not show an example; the above matrix circuit M is In: Similarly, three common mode amplifiers A to IP+, Layer 1) 6
AMPIl:Fj, t and one inverting amplifier AMP7
And the output resistor r1 connected to each of these amplifiers is
r4, each amplifier AMr'h~AM
P8 except for the in-phase and inversion functions is U' and its amplification factor is, for example, a % value, Ij' L, respectively. (1)
b is the input terminal of 41 signal L + H, +2)l) is)
Three signals 1. -R's input terminal, (1) c is the left-hand side numbered output terminal, (2) C is the right-hand side's j"j -":fR output terminal.

Next, the action will be explained.

In the illustrated example in FIG. 2, the additional circuit UO is connected to terminal (2) a
b, that is, the iJλ path of the difference No. 111 L-R, but if desired, the mustard (1) a (1Jb, that is, the line of the sum signal L+R) is interposed. When the left signal and the right signal R are separately introduced into the circuit M, the left and right signals are matrixed and a difference signal L-R flows through the attached circuit U, reducing the noise of the difference signal at the low frequency stage. Then, the sum signal L-1-R and the difference signals I, ~R are decoded by the dematrix circuit DM) IJ
A left signal R and a right signal R are respectively derived from the output terminals (1)c and (2)c. This left and right signal LR
is switched by switching circuits U and U2, and then superimposed by U3 to generate a carrier suppression layer modulation signal (sub signal) (LR) which forms a composite signal for main carrier modulation.
D811 and output from the output terminal (3).

At this time, the noise of the difference signal L-R has already been reduced at the low frequency stage, so even if it is in the form of sub-A, this noise reduction effect is almost the same! The composite signal that is maintained and the noise of the 1-1 sub-m is reduced is fiJ':) fl3, and the sum signal L+R line is connected to the line of the sum signal L+R). Even when the 4 circuit Un is inserted, its noise reduction effect is , L as above and PCl''I: Same.

In addition, the first implementation (・1 is tyo visit A! i circuit Nobuto unit)
When U4 is interposed in the stereo modulator/ζ:), the noise reduction effect is as described in step 1. -O#iJ,
The same applies to the case where the 1lltI device is used. This - cheering υ': The noise included during reception is reduced,
l) The left and right Buddhist symbols LR are obtained.

Next, FIG. 5 shows a second embodiment of the invention.

On the same day, the applicant issued a notice regarding Ibisu AaI.1. ! The name of i'l is "stereo modulator", and the frequency deviation n of the main 1:2:i transmission wave by the main signal is
When the skin frequency (ffi shift m is set to 2 times, for example; j A JJ (an example is shown) in which the JJ-related scrap circuit insertion method applied to a stereo modulator is applied. The symbol Ma in the figure is a special matrix circuit, and the left and right signals LR are input separately, and the I, A mixed signal of 1.DELTA.1.-.DELTA.R and R1.DELTA.R-.DELTA.L is output.

Here the value of Δ is Δ=! A (Sato-1) It is defined by the formula, and when C=2, Δ=%.

Even when applied to such a stereo modulator, the attached circuit insertion unit Ua is inserted into the parallel line portion of the left and right signals LR in the device, and its insertion position is the front stage of the special matrix circuit Ma. Become. At this time, the dematrix circuit DM in the attached circuit insertion unit U4
and 1a to the special matrix circuit can be formed as one combined 7 matrix Mb. That is, the combination matrix Mb is created by inputting the sum signal L-R and the difference signal L-R separately. It is only necessary to adjust the outputs of each of the input terminals 111 ΔR and R1 ΔR - ΔL.

Show the internal 4Pi composition of this coupling matrix in the form of a formula for the result f.
-482% (L+R; -(%1Δ) (Summer, -Summer R-
ΔR-ΔL-% (L 1R) - (j4 18) (L-1 clause, that is, the function of multiplying the input sum signal (L0R) by %, and the difference signal (t - R) by (% + Δ) Double (4ifit Shino)
In addition, by adding a function to add fi and subtract n to each magnification, it becomes one combined 71 risk.
(1^ It is possible to accomplish.

The operation is almost the same as that of the first embodiment, and the composite signal /ζru1, -1-R1''/, (T-1-R几8
The main signal L -1-R of 8 is still the sub signal +y, (
L 1 R) Reduces the noise of Its□ at the low frequency signal stage.

Next, FIG. 6 shows a third embodiment of the present invention.

This embodiment is a 4J (example is shown. In the matrix circuit, I, +ΔI7−ΔR and R+Δ]
ΔLT? Output the left and right signals of ΔR separately.

In this case, the auxiliary circuit insertion circuit U4 is arranged after the special dematrix circuit DMa. In this case, the 7-trix circuit M in U4 and the matrix circuit DMa are configured as one combined dematrix circuit Md. can. That is, the combined dematrix circuit Md separately introduces the mixed signals (1, 1 + ΔL - ΔR and 1 + ΔR - ΔL), and calculates the sum (g 1. +R and difference signals I, -R
All you have to do is output it. The internal formation of this coupled dematrix circuit Md can be expressed as a mathematical formula for only the result1, L+R=(L+ΔI, -Δu)+(R−Δy to R0,)
LR=-↓-((I, +ΔI5-ΔR) −(R+Δ
R-ΔL)) J+2Δ In other words, L0ΔL-ΔR and R0ΔR-ΔL are combined to output a sum signal 1, 10R, and from L0ΔL-ΔR, I(10ΔI
- ΔL is subtracted from this and desired 1. -2Δ) ko1? do! j! I have NI Tsuji.

As for the action, input signal f18 is input, main signal behind No. 1 is Hatake sub(is), sum No. 474 1-I Rt
t', the noise is reduced in the form of the difference latent code L-R, and the left signal l,
Circle, 1, and sum signals R are output separately.

As detailed above, according to the present invention, the left and right signals LR are introduced separately, and the left and right signals 1. - same sum signal (L+
R) and difference 1' signal (t, -R) output separately for each input circuit, and the above sum signal (L+p) and difference signal (L-R) are introduced to output left, right ( The dematrix circuit that outputs Wf kel-1? separately, and the sum signal between these 7 matrix circuits and the dematrix circuit are interposed in either of the difference signal lines./This noise reduction 3. Configure the attached circuit Okijin j, 2 y I□ with the attached circuit such as the Zocon circuit, and connect this attached circuit insertion unit to the transducer converter or stereo demodulator. -Ruru/j: Since the right signal R is interposed on the parallel line of R,
Even in a stereo modulator/demodulator that does not have a sum signal line or a difference signal line in the equipment, the sum (
This has the effect of reducing noise in the if signal or the difference signal. Therefore, it is possible to provide a more suitable auxiliary circuit insertion method for a stereo modulating φ demodulator that employs a switching method that provides stable separation between the main and sub signals. It will be done.

[Brief explanation of the drawing]

Figure 1 is a professional diagram showing a conventional stereo modulator.
Fig. 2112 is a block diagram partially omitted showing a first embodiment of the auxiliary circuit insertion method in a stereo modulator/demodulator according to the present invention, and Fig. 3 shows an example of a matrix circuit applied to the first embodiment. 4 is a circuit diagram showing an example of a dematrix circuit applied to the first embodiment, FIG. 5 is a block diagram showing a second embodiment of the present invention, and FIG. 6 is a circuit diagram showing an example of a dematrix circuit applied to the first embodiment. 3 Some examples are omitted (2 is not shown)
- (Z exists. M: Matrix circuit DM: Dematrix circuit Uo: Noise rig 4F 1F times h'!S Ding F's inquiry (14
Circuit UI+ U2 'Stereo iU Ij"j'/l
：÷￥Edited ・1 notching circuit U4: Attachment 5; ・Pe circuit insertion 1 nit U6, U6: Ideal for stereo demodulator) V notching circuit management 'I'jj, Agent Co., Ltd. Ashi Page 111 E'tsu 3 figure M? 1\4 Figure M

Claims (1)

[Claims] The first audio signal (L) and the second audio signal (R) are introduced separately, and the first audio signal (L) and the second audio signal (
A matrix circuit that separately outputs the sum signal (L+R) and difference signal (L-R) of R) and the sum signal (L+R) and difference signal (L-R) are introduced to generate the first audio signal ( A dematrix circuit that separately outputs the second audio signal (R) and the second audio signal (R), and a noise reduction circuit or the like interposed between the matrix circuit and the dematrix circuit by the fall of the sum signal line or the difference signal line. The circuit constitutes an auxiliary circuit insertion unit, and the auxiliary circuit insertion unit is used to generate the first audio signal (R number (L) and second audio signal (R) in parallel) in the stereo modulator or stereo demodulator. A method of inserting an auxiliary circuit in a stereo modulator/demodulator, which is characterized by intervening it in the line.