JPH01143513A - Signal level compression and expansion device - Google Patents

Abstract

PURPOSE:To easily obtain a level compander having a required compression and expansion ratio by providing a power (a) circuit converting a value of a 1st control signal into a value of power (a) and outputting the result as a 2nd control signal. CONSTITUTION:A gain control circuit 3 receives an input signal VIN from an input terminal 1 and receives a control signal I'K from a control terminal 8 and outputs an output signal VOUT from an output terminal 2 and gives either the input signal or the output signal to a level detection circuit 4. The circuit 4 receives a signal VOUT from a level detection input terminal 5 and outputs the result to a control terminal 7 as a control signal IK. The power (a) circuit 9 receives the signal IK from the terminal 7 and outputs the signal I'K to a control terminal 8 as the result of power (a) onto the signal IK. Thus, the signal VOUT from the circuit 3 is outputted as a compressed signal of VIN/(a+1). An expander outputs an output signal VOUT similarly as the expansion of the input signal VIN by a multiple of (1+a).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is a method for converting an input signal level into a signal level compressed or expanded to an arbitrary M:N ratio in an installed electronic device, and outputting the converted signal level as an output signal. This invention relates to a signal level compression and expansion device.

BACKGROUND ART In general, in a signal level compression circuit, a gain control circuit 3 receives an input signal V from an input terminal 1 and a control signal IK from a control terminal 6, as shown in FIG. The output signal voUT is controlled and output according to the relationship shown in equation (1).

However, K1 is a proportional constant. Next, the level detection circuit 4 receives the output signal V of the gain control circuit 3 from the level detection circuit input terminal 5. It receives U, and outputs it to the control terminal 6 as a control signal after converting it into the relationship shown in equation (2).

Work = 2 x voUT ・・・・・・・・・・・・
・・・・・・・・・・・・(2) However, K- is a constant of proportionality. Here, substitute equation (2) into equation (1) to obtain.

Equation (3) shows that the input signal vxN is compressed to the i power and output as the output signal VOUT.

Similarly, in the signal level expansion circuit, as shown in FIG. 6, a gain control circuit 3 receives an input signal vIN from an input terminal 1 and a control signal IK from a control terminal 6.

The output signal vOυT from the output terminal 2 is controlled and outputted according to the relationship shown in equation (4).

vOUT=Ks×I KxV IN −−−−−−
--------(4) However, K3 is a proportional constant. Next, the level detection circuit 4 receives the input signal vIN of the gain control circuit 3 from the level detection circuit input terminal 6, and sends it to the control terminal 6 as a control signal lK. It is converted into the relationship shown in equation (6) and output.

IK=4×vIN ・・・・・・・・・・・・
...-(5) However, K4 is a constant of proportionality. Here, substituting equation (5) into equation (4), VOUT = K 3 X K 4 XV I N
---"" (6) is obtained.

Equation (6) shows that the input signal VOUT is expanded to the second power and output as the output signal VOUT.

Problems to be Solved by the Invention However, the conventional configuration described above only performs compression and expansion based on negative and square relationships.

The present invention provides a means that enables compression and expansion of any M power or N7M power.

Means for Solving the Problems The present invention provides a gain control circuit whose gain is controlled by a second control signal, a level detection circuit which outputs a first control signal proportional to the input signal level, and an a-th power circuit that receives a first control signal, converts the value of the first control signal to a value raised to the sixth power, and outputs the result as the second control signal, and the input signal of the gain control circuit is The signal level compression/expansion device is characterized in that either one of the output signal and the output signal is input to the level detection circuit.

Operation According to the above configuration, the compression and expansion ratios can be changed by changing the a value of the α power circuit, and the a value of the α power circuit can be changed.
Since the values can be easily varied, it is easy to obtain a level compression/expansion device having the required compression or expansion ratio.

Embodiment FIG. 1 is a block diagram of a signal level compression apparatus according to an embodiment of the present invention.

In FIG. 1, the gain control circuit 3 inputs an input signal vIN from an input terminal 1 to a second control signal I from a second control terminal 8.
In response to the signal K/, the output signal voUT from the output terminal 2 is controlled to have the relationship shown in the equation (@) and is output.

However, K1 is a proportional constant. Next, the level detection circuit 4 receives the output signal voUT of the gain control circuit 3 from the level detection input terminal 6, and sends it to the first control terminal 7 as the first control signal IK according to equation (9). It is converted into the relationship shown in and output.

IK=2×vOUT eee … …
…−1・ …(9) However, K2 is a proportional constant α power circuit 9 receives the first control signal IK from the first control terminal 7
In response, the second control signal IK' is converted to the relationship shown in equation (1o) and output to the second control terminal 8.

■N′=β1XIK 1 ・・・・・・・・・・・・
・・・・・・・・・・・・(10) However, β is a constant of proportionality. Substitute equation (9) into equation (10) here! ′=β1×
(K2×voUT) al・・・・・・・・・・・・(1
1), then substitute equation (11) into equation (8) to obtain.

Equation (12) shows that the input signal vIN is compressed to 1/α1+1 and output.

Similarly, in the signal level expansion circuit, as shown in FIG.
The output terminal 2 receives the control signal IK/ from the control terminal 8 and outputs the output signal after controlling it to the relationship shown in equation (13).

VOUT = 3 X I K' x V I N ・
= −・= −−(13) Next, the level detection circuit 4 receives the input signal v from the level detection input terminal 6 to the gain control circuit 3.
Upon receiving IN, the first control signal X is sent to the first control terminal 7.
K is converted into the relationship shown in equation (14) and output.

= 4 x vIN ・・・・・・・・・・・・・・・
(14) The α power circuit 9 is connected to the first control terminal 7
After receiving the first control signal K, it is converted to the relationship shown in equation (15) and output as a second control signal IK' to the second control terminal 8.

IK' = β2 x engineering 2 ・・・・・・－・・・・・・・・・
・・・・・・・・・(16) However, β2 is a constant of proportionality. Substituting equation (14) into equation (15), IK'=7?
2×(K4・
・・・・・・・・・・・・・・・(17) is obtained.

Equation (17) shows that the input signal vIN is expanded to α2+1 and output.

In equations (12) and (17), K1− is 3· K2= is 4 a1=α2. With the relationship β1=β2, equation (12) + equation (17) becomes α1
It shows that compression and expansion are performed according to the +1 power relationship.

When compressing to the power of M and expanding to the power of N7M, set it as M α1+1 N.The value of α is M ・・・・・・・・・・・・・・・・・・
−(18) may be used.

Below, as an example of the present invention, compression is performed to the 3/4 power.

The case of expansion to the 4/3 power will be explained.

If α=--1=- is obtained in equation (18) and a 1/3 power circuit is realized, the indenter 8 receives the second control signal IK' as a current value to the 3/4 power, and the current value Suppose that the gain is controlled by .

It is also assumed that the level detection circuit 4 outputs a current value proportional to the level of the signal input from the level detection input terminal 6 to the first control terminal 7 as the first control signal XK.

The α power circuit 9 converts the current value input from the first control terminal 7, which becomes the first control signal, into the current value IK/ shown in equation 19, and outputs it to the second control terminal. Second control signal! You can output it as ′.

5 ・・・・・・・・・・・・・-(19) IK′
=β×work An embodiment of this α power circuit 9 is shown in FIG.

The α power circuit shown in FIG. 3 will be explained. At this time α=i
So, it is called a 1/3 power circuit.

The first control signal, which flows into the diode-connected transistor Q1, is transmitted to the collector of the current mirror transistor Q2. At this time, the emitter potential vA of the transistor Q6 is expressed by equation (2).

・・・・・・・・・・・・・・・・・・ (20) However, vcc: Power supply voltage,! . : Current value IsP of constant current source 1o: Saturation current q of PNP transistor: Amount of charge of electrons T: Temperature To the second control signal, ' is output from the collector of transistor 09 configured as a current mirror, and the output When calculating the base voltage VB of the transistor Q8, the formula (2+) is obtained.

Naturally, vA=VB, and from equation (2o) + (2'), 1, = 1 honor xI ”K OK °°'”'”°”'“°°”
-(22) is obtained.

This equation (22) shows that the first control signal K is converted in a first power relationship and output as the second control signal Z.

Effects of the Invention As described above, according to the present invention, it is possible to easily configure an α-th power circuit, thereby easily compressing M-th power, N7M
Expansion to the power is possible.

This is highly effective in that it allows the signal level to be converted to an optimal level.

[Brief explanation of the drawing]

1 and 2 are block diagrams of a signal level compression device and an expansion device, respectively, in one embodiment of the present invention, FIG. 3 is an electrical circuit diagram of the same essential parts, and FIGS. FIG. 2 is a block diagram of a signal level compression device and decompression device. 1...Input terminal, 2...Output terminal, 3
... Gain control circuit, 4 ... Level detection circuit, 6 ... Level detection circuit input terminal, 6 ...
...Control terminal, A...First control terminal, 8
. . . Second control terminal, 9 . . . α power circuit, 10 . . . Constant current source. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
figure,? Figure 3

Claims (1)

[Claims] a gain control circuit whose gain is controlled by a second control signal; a level detection circuit which outputs a first control signal proportional to the input signal level; an α-th power circuit that converts the value of the control signal to the α-th power and outputs it as the second control signal; A signal level compression and expansion device characterized by inputting to