JPS5919517B2 - Multi-frequency signal reception method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-frequency signal reception method, and in particular to a method for converting an input signal, which is a signal used for audio frequency dial signals, etc., and which is composed of a plurality of different frequencies into a DC output signal, and converting the input signal to a DC output signal. The present invention relates to a signal receiving method for applying a signal to corresponding points among a plurality of output points according to the frequency of the input signal.

Conventionally, a configuration as shown in FIG. 1 has been used as this type of multi-frequency signal receiver.

That is, when a plurality of mixed signal waves of different frequencies arrive at the input terminal IN, the mixed signal waves are first passed through a common bandpass filter MBF. This common bandpass filter MBF is used to separate the selected signal group from signals outside the frequency band that are mixed into the input terminal IN in a pre-required frequency band. The output of this filter MBF is divided into multiple separation circuits CHBPF provided for each frequency.
It is given in branches. Each separation circuit CHBPF is constituted by a bandpass filter having its own pass frequency band, and extracts a wave of a selected frequency from a frequency group of an input signal, and outputs only its component. Each separation circuit C
The output of the HBPF is connected to the input of a discriminator circuit DET provided corresponding to each frequency, and compared with a threshold value, and the result is converted into a binary pulse signal.
It is output to Xn. In a conventional multi-frequency signal receiver having such a configuration, the separating circuit CHBPF requires bandpass filters each having the same number of unique pass frequency bands as the number of input signal frequencies.

The design of these bandpass filters is complicated, requiring the design of many types of filters, and the manufacturing process is also accompanied by difficulty in manufacturing many types of filters. The present invention is an improvement on this, and aims to provide a multi-frequency signal receiving system configured by one type of filter circuit.

The present invention includes: a first modulator having one input connected to an input terminal and a constant frequency signal connected to the other input; and a filter having an input connected to the output of the first modulator. a plurality of second modulators each having one input connected to the output of the filter; a separation circuit having an input connected to each output of the second modulator; and a separation circuit having an input connected to each output of the second modulator; a discriminator circuit connected thereto, the filter is configured to extract either the sum or difference of signal frequencies applied to the two inputs of the first modulator, and A signal of a multi-frequency signal to be detected is applied to the other input of each of the two modulators, and the separation circuit is a bandpass filter having a passband of the constant frequency.

Next, the present invention will be described in more detail with reference to the drawings. FIG. 2 is a circuit configuration diagram showing an embodiment of the present invention.

A first modulator M is connected to the input terminal 1N, and its output is sent via a common filter CF to a second modulator M2j (j2o to n) provided for each frequency band. It is connected. The output of each modulator M2j is connected to a separation circuit CHBPF composed of band pass filters having the same type of pass frequency band, and the output thereof is connected to the input of a discriminator circuit DET provided corresponding to the frequency band. It is connected to the.

To explain the operation of the device configured in this way, the operation is to change the frequency of the input signal reaching the input terminal 1N to F8l (1=
o-n), and a constant frequency F is applied to the modulator M, to the terminal C, and to the terminal C.
.

,give. Both sideband waves are output as the output of the modulator M1.

The pass band of this output is limited by the common filter CF connected to the next stage, and only a single sideband wave 1f81-FO,l is extracted as the output. The output of this common frequency filter CF is modulated by the modulation signal of each frequency FO2j supplied from each terminal C, j in the modulator M2, and the output has both sideband waves of ◎1 - Hail.

By selecting F,j as this carrier frequency FO2j, the double-side band waves of the fundamental wave become as follows.

A constant frequency F is the input of the first modulator M1 as each separation circuit CHBPF.

By using a bandpass filter with a passband of 1, the frequency FOl is outputted to the output of the separation circuit CHBPF of the channel 1=j, and the output of the separation circuit CHBPF of the channel ij Only the leakage amount is output.

, that is, when the wave is in an adjacent band, the leakage component is maximum, but these can be discriminated by appropriately configuring the characteristics of the separation circuit CHBPF.

The operation of the discriminator circuit CET connected at the subsequent stage is the same as that of the conventional example shown in FIG. As can be understood from such an operation, the separation circuit CHBPF placed corresponding to the input signal frequency may have the same characteristics for all channels. Furthermore, since the modulated signal supplied to the second modulator M2j is equal to the frequency of each multifrequency signal, it can be obtained more easily than the transmitting device normally paired with the receiving device. In addition to the one described in the above example, the common transducer CF may be of any type as long as it is a transducer that converts both sideband waves into a single sideband wave. For example, in the above example, the present invention can be implemented in the same way even if a low-pass type is used instead of a high-pass type for the common F-wave device CF, and a single sideband wave of F, i + FO, is extracted. As explained above, according to the present invention, it is possible to share the separation circuit by using one type of waveguide circuit, which is convenient for mass production and particularly effective for economical industrialization.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional device.

Claims (1)

[Claims] 1. One input is connected to the input terminal (IN) and a signal of a constant frequency (f_C_1) is connected to the other input.
a modulator (M_1), a filter (CF) whose input is connected to the output of this first modulator, and a plurality of second modulators, each of which has one input connected to the output of this filter. (M
_2j), a separation circuit (CHBPF) whose input is connected to each output of this second modulator, and a discrimination circuit (DET) connected to each output of this separation circuit, CF) is configured to extract either the sum or difference of signal frequencies applied to the two inputs of the first modulator, and A multi-frequency signal receiving system, wherein signals of multi-frequency signals to be detected are respectively applied to inputs, and the separation circuit is a bandpass filter having a passband of the constant frequency (f_C_1).