JPS5883491A - Multifrequency signal detector - Google Patents

Abstract

PURPOSE:To improve the reliability of mis-detection to white noise, by providing a band pass filter taking the entire frequency band of reception signals as the pass band and transmitting a detection signal when the rectified signal level of an output signal is lower than the reference level. CONSTITUTION:An output signal of a band pass filter 23 taking a low group frequency component 21 and a high group frequency component 22 of a reception signal as the pass band, is rectified at the 3rd rectifier circuit 33, and this output signal is applied to the 3rd comparison circuit 43 which produces an output signal when the level is the 2nd reference level VS2 or below set corresponding to the reception level higher than the 1st reference level VS1. When the output signal of the 3rd comparison circuit 43 and that of the 1st and 2nd comparison circuits 41, 42 are simultaneously outputted consecutively for a prescribed time or over, a multifrequency signal can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-wave signal detection device using audio frequencies used as a control signal in a communication switching network or the like. In particular, it relates to a multi-frequency signal detection device that distinguishes between signals and noise.

In general, multi-frequency detection equipment Kti distinguishes between signals and noise, reduces the influence of noise during signal reception, and also compares the signal at a certain level (to confirm that the signal continues for more than a certain time) circuit and a delay circuit.However, in conventional comparator circuits, if the input is above a certain level, it produces an output signal similar to the signal received.For this reason, conventional multi-frequency detection devices Even when noise above the level continues for a specified time or more, it is falsely detected as signal reception.

The present invention eliminates the above-mentioned drawbacks, and the conventional 01! It is an object of the present invention to provide a multi-frequency signal detection device that does not cause an output error when level O noise, which is erroneously detected as a signal reception, is continuously received for a predetermined time or longer.

The present invention compares a conventional comparison circuit with a threshold value of a certain level and a rectified output of a band P-wave generator whose passband is the receiving am4to all-round liquid number band with a threshold value of a certain level. It is characterized by being composed of a comparison circuit and k.

That is, the present invention provides a low group P wave device for extracting the low group frequency component of a received signal, a high group P wave device for extracting the 0 @ group frequency component of the received signal, and an output signal of the low group P wave device and Rectifier circuits No. 1 and No. 20 each rectify the output signal of the high group P-wave device, and when the output signals from these rectifier circuits, which are provided corresponding to these rectifier circuits, exceed the reference level No. 10. A multi-frequency signal detection device comprising a first and second comparator circuit that generates an output signal; A third rectifier circuit that rectifies the output signal of this band R wave generator, and a second standard that is set corresponding to a 9-signal level where the output signal of this third rectifier circuit is higher than the first reference level. and a comparator circuit 30 that generates an output signal when the level is below the level, and the output signal of the third comparator circuit and the output signals of the first and second comparator circuits are simultaneously transmitted continuously for a specified time or more. The present invention is characterized in that it is configured such that a multi-frequency signal is detected when a signal is detected.

The present embodiment will be described in detail below based on the drawings.

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. 1
0 is an input terminal of the detection device, and this input terminal 1O is connected to a low group F wave device 21 for extracting the low group frequency component of the received signal and a high group P wave device n for extracting the high group frequency component of the received signal. connected to each input. The output of the low group P wave device 21 is connected to the input of the rectifier circuit 31, and the output of the high $F wave device n is connected to the input of the rectifier circuit n. In addition, the input terminal 10 is connected to the input terminal Kml of the rectifier circuit (input Kml) via a band P-wave filter n whose pass band is the low group frequency component and the high group frequency component of the received signal. It is a frequency characteristic diagram of low group P wave s21, high group P wave device n, and bandpass P wave device.

The output of the rectifier circuit 31 is connected to one input Kll of a comparator circuit 410, and is also connected to the output of the rectifier circuit and one input KII for the comparator circuit. These comparison circuits 41 and 4
10 and other inputs are given a reference voltage v1 as a threshold value.The output of the rectifier circuit 330 is.

One input of the comparator circuit C is connected to Km, and the other input of the comparator circuit C is given reference voltages v and t as threshold values. This reference voltage v1 is set in response to a higher reception level than the reference voltage v, that is, a higher reception level that cannot occur as a normal multi-frequency signal. The 442% and morning outputs for these comparison circuits are the input El between the NAND circuits.
I was hooked up, this Nando times I @ Shameful output, delay 1 route 60
It is connected to the output terminal 70 via. This delay I bribe 60
is configured to send out an inverted output when input (inverted - human power) is continuously applied for a predetermined period of time or more.

Further, the comparison circuits 41 and C produce an output signal when the output of the rectifier circuit 31 and the output of the proverb are larger than the reference voltage vs, respectively, and the comparator circuit 41 and C produce an output signal when the output of the rectifier circuit
, 2.

With this configuration, the received signal input from the input terminal IO is input to the low group P-wave unit n, the high group P-wave unit SOU, and the belt completion P-wave unit 23, and is input to the equalization circuits 31, 32, and (
It is rectified by

Here, when the white noise is continuously input for more than a specified time and the signal rectified by the rectifier circuit 33 via the band P-wave device becomes equal to or higher than the reference voltage 782 of the comparator circuit C, the output signal of the comparator circuit 43 becomes the rLJ level, the output signals of the comparison circuits 41 and C, that is, the received information of the low group frequency and the high group frequency are ignored, and the output signal between the NAND circuits becomes rLJ level.
The signal becomes LJ level and no output signal is sent out from the output terminal 70, and no output signal is sent out as a multi-frequency signal detection device.

In addition, the output signal of the rectifier circuit is the reference voltage VE at the center of the comparison circuit.
1. y) When Ka is small, the output signal of comparator circuit C is rH
J level), the output signals of Comparison Circuit Co., Ltd. and C, that is, the output signals of the multifrequency signal detection device according to the received information of the low group frequency and the high group frequency are sent out.

As described above, according to the present invention, it is possible to use the conventional table-mounting method. A band P-wave device whose pass band is the entire frequency band of the flaw signal is provided, and the configuration is configured to send out a detection signal when the rectified signal level of this output signal is lower than the reference level.From K, white noise is specified. Even if the signal continues for more than a certain period of time, this can be prevented from being mistakenly detected as a multi-frequency signal input.

This has the excellent effect of improving detection reliability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. Figure 2 is also a frequency characteristic diagram of the f-wave device. lO...Input terminal, 21...Low group f-wave device, n--high group P wavesha, C%--comparison circuit, listen...Nand circuit,
6o...Delay circuit, 70--output terminal.

Claims (1)

[Claims] (1) A low group e-wave device (21) for extracting the low group frequency component of the received signal, a high group P-wave device (22) for extracting the high group frequency component of the received signal, and the low group r-wave device output signal and high group PI! First and second rectifier circuits (31, 32) that rectify the output signals of the
A multi-frequency comparator circuit comprising first and second comparator circuits (41, 42) provided corresponding to the WA path and generating an output signal when the output signals from these rectifier circuits exceed the tenth reference level. In the signal detection device, a band P-wave device (23) that uses both the low group frequency component and the high group frequency component of the received signal as passbands, and a third rectifier circuit that rectifies the output signal of this band P wave device. (33) is provided corresponding to the third rectifier circuit, and the output from this rectifier circuit is below the second reference level set in response to the reception level higher than the above-mentioned 10th reference level. 30 comparison circuit 1 (43) which generates an output signal when A multi-wave signal detection device characterized in that it is configured to detect frequency signals.