JPS6120196B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-frequency signal receiving system that receives a two-frequency signal representing one state with two frequencies and determines the state represented by the received signal.

In the conventional multi-frequency signal reception system used between push-button telephones and telephone offices, the input two-frequency signal is passed through a separation filter 1, as shown in FIG.
After separating these signals into a high group and a low group at
A predetermined frequency and a level are detected through a level detector 3, and the state is determined by a matrix circuit 4 based on the output. However, this method uses two bandpass wavers corresponding to each frequency.
This has the disadvantage of increasing the size of the multifrequency signal receiver.

On the other hand, the multi-frequency signal reception system used between telephone offices as shown in Figure 2 has the same configuration as that shown in Figure 1, except that the separation filter shown in Figure 1 is not used, so it is still possible to receive The container becomes large.

An object of the present invention is to provide a multi-frequency signal receiving device whose circuit can be simplified by detecting frequencies without using a filter.

First, the basic principle of the present invention will be described. A multifrequency signal consisting of angular frequencies ω ₁ and ω ₂ is generally expressed as follows.

V(t)=A ₁ cos (ω ₁ t+ ₁ ) +A ₂ cos (ω ₂ t+ ₂ )+C……(1) However, A ₁ and A ₂ are the amplitude values of the respective frequency components, ω ₁ and ω ₂ is the angular frequency, ₁ and ₂ are the phases, and C is the DC component.

The present invention utilizes the dependency relationship between the sample values obtained by sampling V(t) at equal intervals on the time axis, and detects the received frequency using only four arithmetic operations using the sample values. .

Let γ be an arbitrary time and T be a sampling interval that satisfies the sampling theorem. Let K be any positive number, V
Obtain sample values V(γ) to V(γ+8KT) from (t). Next, using this sample value, β ₁
~ Calculate _β4 .

β ₁ = V (γ + 5KT) - V (γ + 3KT) ... (2) β ₂ = {V (γ + 6KT) - V (γ + 2KT)} / 2 ... (3) β ₃ = {V (γ + 7KT) - V (γ + KT ) +β ₁ } / 4 ... (4) β ₄ = {V (γ + 8KT) −V (γ)} / 8 + β ₂ / 2 ... (5) Substitute V (t) of equation (1) into the above equation , by applying the trigonometric formula, the following simultaneous equations are obtained.

β ₂ α ₁ −β ₁ α ₂ =β ₃ ...(6) β ₂ α ₁ -β ₂ α ₂ =β ₄ ...(7) Here, α ₁ = COSω ₁ KT+COSω ₂ KT ...(8) α ₂ = COSω ₁ KT×COSω ₂ KT (9) Based on this equation, α ₁ and α ₂ can be calculated as follows using the four arithmetic operations β ₁ to _{β 4} .

α ₁ = N ₁ /D …(10) α ₂ = N ₂ /D …(11) However, D = β ² ₂ + β ₁ β ₃ …(12) N ₁ = −β ₂ β ₃ + β ₁ β ₄ ... (13) N ₂ = β ₂ β ₄ - β ² ₃ ... (14) On the other hand, the combination of α ₁ and α ₂ in equations (8) and (9) becomes the combination of ω ₁ and ω ₂ . There is a one-to-one correspondence. Therefore,
By determining (α ₁ , α ₂ ), (ω ₁ , ω
₂ ) can be obtained.

In the present invention, by selecting α ₁ and α ₂ as parameters, a combination of two frequencies is determined from sample values of a received signal using only four arithmetic operations.

Next, an embodiment of the present invention based on the above-mentioned principle is shown in FIG. First, a switch 61 that opens and closes at a cycle of T (seconds) causes the received two-frequency signal V(t) to
sampled at KT (K=1), each in T (seconds)
A plurality of delay devices 6 connected in series have a delay time of
V(γ+iT) (i=0, 1, . . . 8) is obtained as the output of 2, respectively.

Furthermore, the signal lines 101 to 104 each have a formula
β ₁ to β ₄ based on (2) to (5) are obtained. here,
Reference numeral 63 is an adder, reference numeral 61 is a 1/2 multiplier, reference numeral 66 is a 1/4 multiplier, and reference numeral 61 is a 1/8 multiplier. Furthermore, equations (12), (13) and (14) are applied to signal lines 105, 106 and 107, respectively.
Based on D, N ₁ and N ₂ are obtained. here,
The same number 64 is a multiplier. Furthermore, the signal line 10
8 and 109, α ₁ and α ₂ are obtained based on equations (10) and (11), respectively. Here, the same number 6
8 is a divider. Signal lines 108 and 109 are connected to circuit 7. The circuit 7 can be configured by a program-controlled device such as a microprocessor.

This circuit 7 calculates the corresponding ω ₁ from the combination of α ₁ and α ₂ obtained from the signal lines 108 and 109.
The combination of and ω ₂ is determined. In this way 2
Can determine the state of a frequency signal.

As described above, when the multi-frequency signal receiving device of the present invention is used, a bandpass filter and a separation filter are no longer necessary, so that the receiver can be miniaturized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a receiver for receiving multi-frequency signals from a conventional push-button telephone;
1 is a block diagram of a conventional receiver for receiving multi-frequency signals between telephone offices, and FIG. 3 is a diagram for explaining an embodiment of the present invention. In the figure, 1...separation filter, 2...band pass wave generator, 3...level detector, 4...matrix circuit, 7...circuit, 61...switch, 62...delay device, 63...addition Device, 64... Multiplier, 65...
...1/2 multiplier, 66...1/4 multiplier, 67...1/8
Multiplier, 68...Divider, 101-109...Signal line.

Claims (1)

[Claims] A signal V _{( t} ) V( _A plurality _of sample _values V( _γ ) _or V(γ ₊
8KT), a means for obtaining β ₁ to β ₄ given by the following formula from the plurality of sample values, and β ₁ = V (γ + 5KT) - V (γ + 3KT) β ₂ = {V (γ + 6KT) - V ( γ+2KT)}/2 β ₃ = {V(γ+7KT) −V(γ+KT)+β ₁ }/4 β ₄ = {V(γ+8KT) −V(γ)}/8+β ₂ /2 From this β ₁ to β ₄ D given by the formula,
_{A means for calculating N 1 and N 2} ^and _{_ _ _ _} ^_ _{_ _ _} Means for calculating values corresponding to α ₁ and α ₂ given by the following equations by dividing by D respectively, and α ₁ = cosω _{1 KT} + cosω ₂ KT α ₂ = cosω ₁ KT×cosω _{2 KT} From the values corresponding to ω ₁ and ω
2. A multi-frequency signal receiving device characterized by comprising: means for determining a combination with ₂ .