JPS6115665Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field of the Invention) The present invention relates to a multi-frequency signal receiver, and in particular converts an input signal in which different frequencies are combined into a DC output signal, and converts the output signal into a DC output signal. The present invention relates to a signal receiver for applying a signal to corresponding points of a plurality of output points according to the frequency of the signal.

(Prior art) Conventionally, as this type of multi-frequency signal receiver, the first
A configuration as shown in the figure is used. That is, when a plurality of mixed signal waves of different frequencies arrive at the input terminal IN, the mixed signal waves are first input to a common bandpass filter MBF. This common band filter MBF uses its frequency band to separate the selected signal group from signals outside the frequency band that are mixed in the input signal. This common band filter
The output of the MBF is branched and given to a plurality of separation devices CHBPF provided for each frequency band. Each separation device CHBPF is constituted by a bandpass filter having its own pass frequency band, extracts a wave of a frequency within a selected band from a frequency group of an input signal, and outputs only its component. Furthermore, each output is connected to the input of a discriminator DET provided corresponding to each frequency band, and compared with a fixed threshold value, and the result is converted into a binary pulse signal and output.

On the other hand, the output of the common band filter MBF is also connected to the input of a gate timer circuit GT to control the timing system of the receiver. The gate timer device GT is configured to generate a plurality of pulse trains after a predetermined delay time after the output of the common band filter MBF reaches or exceeds a set threshold level.

The output of the discrimination device DET indicates the presence or absence of an output after separation into each frequency band, and this information is stored in the information storage device INT after a time determined by the output pulse of the gate timer device GT.
By storing the input signals at different frequencies, a plurality of input signals can be converted into a DC output signal, and the DC output signals can be output from terminals X0 to X1.
Output to X5.

In a conventional multi-frequency signal receiver with such a configuration, when the input level range consisting of different frequencies is wide, the output level range of the separation device CHBPF is also wide, and therefore the threshold value of the discriminator DET is the lowest. It needs to be below the emotional level. Furthermore, since the separation device CHBPF is not an ideal bandpass filter, waves in the adjacent band are leaked and output. This effect can exceed the threshold of the discriminator DET when a high input level critical frequency arrives. This is a condition that is contradictory to lowering the threshold value, and to solve this problem, the order of the separation device CHBPF is generally increased and Q is increased. For example, the multi-frequency receivers currently used in telephone exchanges,
It is a 6th order bandpass filter, and the maximum Q of each second order is about 30.

Further, Japanese Patent Application Laid-Open No. 52-34609 describes a multi-frequency signal receiving system in which the threshold value of a discriminator is controlled by the rectified level of a group of received signals input to a separator. However, this conventional multi-frequency signal receiving system also has problems in terms of noise malfunctions.

As mentioned above, in the conventional multi-frequency signal receiver,
The separation device CHBPF is complicated and requires precision, making it expensive, and in particular, constructing it with an active filter, making it into a hybrid integrated circuit, and trimming its functions requires considerable manufacturing complexity. Furthermore, if the frequencies of the signal and out-of-band noise are close, the order of the main band filter MBF becomes high, making it complex and expensive.

(Purpose of the invention) The purpose of the invention is to improve the complexity of the circuit and the difficulty in manufacturing as described above, to simplify the circuit, and to provide a multi-frequency signal receiver with excellent characteristics. It is.

(Summary of the invention) The multi-frequency signal receiver of the present invention receives a signal in which two or more frequencies are mixed, and includes a separating device for distinguishing a selected signal from among the received frequency signals, and a separating device for discriminating a selected signal from among the received frequency signals. an arithmetic device whose inputs are the input and output of the device, and which performs an arithmetic operation to remove the selected frequency signal; an output of the arithmetic device is compared with an output of the separation device; A discriminator that outputs an output when the frequency is large is provided for each frequency band, and a threshold value is generated independently in each frequency band to discriminate the corresponding output.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the block diagram of FIG.

The input received at the input terminal IN is input to a common bandpass filter MBF, and its output is input to a separation device CHBPF provided for each frequency band. The input and output of the separation device CHBPF are input to the calculation device CAL, and the output of this calculation device CAL and the output of the separation device CHBPF are input to the discrimination device
Input to DET. Further, the output of the discriminator DET is input to the information storage device INT, and DC output signals X0 to X5 are output. In addition, a gate timer device GT is used to control the timing system of the receiver.
The provision of is similar to the conventional example.

The operation in the above configuration is performed by one (or more than one) of the separation devices CHBPF for each frequency band.
When the most dominant frequency is reached, thresholds are generated independently in each band and the corresponding outputs are discriminated. Therefore, malfunctions due to leakage of adjacent frequency bands as seen in conventional multi-frequency signal receiving systems are eliminated, and furthermore, it is possible to lower the order of the bandpass filter of each separation device CHBPF.

That is, when a two-frequency signal arrives at the input, one signal is output to the output of the separation device CHBPF corresponding to that one frequency. At that time, the computing device
If CAL is configured with an addition or subtraction circuit to remove a corresponding frequency signal, the input signal is the other signal at the output of the arithmetic unit CAL. The calculation device performs appropriate weighting in consideration of the input level difference between the two frequency signals.
By comparing the output of CHBPF and the output of the arithmetic unit CAL, an output is obtained for each discriminator DET.

In addition, a separation device that does not correspond to the input signal frequency
CHBPF outputs the leakage component, and most of the input signals are output to the arithmetic unit CAL.It is clear that if weighting is performed and comparative detection is performed by each discriminator DET, the corresponding signal will not appear. .

In this way, by providing the arithmetic unit CAL for each frequency band, signal reception can be performed using a low-order separation device CHBPF. Further, the arithmetic unit CAL can be easily configured using an operational amplifier or the like.

(Effects of the invention) By configuring the invention as described above, a multi-frequency signal receiver with excellent noise characteristics can be obtained. This will be explained with reference to FIG. Figures 3a and 3b are block diagrams for explaining the S/N characteristics of the conventional multi-frequency signal receiver and the multi-frequency signal receiver of the present invention, respectively, where CHBPF is an arithmetic unit, DET is a discriminator, and CAL
is an arithmetic unit, and REC-TH is a rectifier/threshold value generator.

Here, the frequency input to the discriminator DET
S is the value of ₀ (signal component), N is the value of frequency ₁ (noise or adjacent signal component), and V _{i 0} is the value of frequency ₀ in the output from the arithmetic unit CHBPF when input V _i is input. The separation device
When CHBPF has attenuation l at frequency ₁ ,
When the input V _i is input to this separation device CHBPF, the output of frequency ₁ is l・V _{i 1} , and the output of the rectifier/threshold generator (REC-TH) with amplification degree k is k・V
_i , the frequency ₀ output of the arithmetic unit CAL with the amplification degree k is k(V _i −V _{i 0} ), and the arithmetic unit with the amplification degree k
The output of frequency ₁ of CAL is k(V _i −l・V _{i 1} )
Then, the conventional method shown in Fig. 3a
34609), it is given by S=V _{i 0} −kV _i …(1) N=l·V _{i 1} −kV _i …(2). Therefore, the S/N at the input of the discriminator DET is calculated from equations (1) and (2) as follows: S/N = (V _{i 0} - kV _i ) - (l·V _{i 1} - kV _i ) = V _{i 0} −l·V _{i 1} …(3).

On the other hand, in FIG. 3b showing the case of the present invention, S=V _{i 0} −k(V _i −V _{i 0} )=(1+k)V _{i 0} −kV _i …(4) N=l・V _{i 1} −k(V _i −l・V _{i 1} ) = (1+k)l・V _{i 1} −kV _i (5) Therefore, from equations (4) and (5), S at the input of the discriminator DET /N, S/N={(1+k)V _{i 0} −kV _i } −{(1+k)l・V _{i 1} −kV _i } =(1+k)(V _{i 0} −l・V _{i 1} )
…(6) becomes.

Therefore, as is clear from a comparison of equations (3) and (6), the present invention has (1+k) times more protection against frequency discrimination noise malfunctions than the conventional one.

Further, according to the present invention, the separation device can be simplified and its performance is superior to conventional multi-frequency signal receivers.

Furthermore, it is particularly effective in economicalization and industrialization as well as miniaturization and high reliability.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing an example of a conventional multi-frequency signal receiving system, Figure 2 is a block diagram showing an embodiment of the present invention, and Figures 3a and b are S/N ratios of the conventional and present invention, respectively. FIG. 3 is a block diagram for explaining characteristics. MBF: common band filter, CHBPF: separation device,
CAL: Arithmetic device, DET: Discriminator, INT: Information storage device.

Claims (1)

[Claims for Utility Model Registration] A separation device for receiving a signal in which two or more frequencies are mixed and distinguishing a selected signal from the received frequency signal, and an input and an output of the separation device. an arithmetic device that operates to remove the selected frequency signal; and a discriminator that compares the output of the arithmetic device with the output of the separation device and outputs an output when the output of the separation device is larger. , are provided for each frequency band, and a threshold value is generated independently in each frequency band to discriminate the corresponding output.