JPH03211946A - Detecting method for terminal equipment call signal - Google Patents

Abstract

PURPOSE:To identify an incoming call signal and a dial pulse signal from a parallelly connected terminal equipment regardless of the electric state of a telephone line without fail and to prevent malfunction by providing a voltage detecting circuit, incoming signal detecting circuit and call signal identifying circuit. CONSTITUTION:A voltage detecting circuit 1 is provided to identify and output whether telephone lines L1 and L2 are turned to a closed loop state or an opened loop state by detecting a voltage impressed to the telephone lines L1 and L2, and an incoming signal detecting circuit 2 is provided to detect the signal to be impressed to the telephone lines L1 and L2 and to output the impression of the signal. Then, a call signal identifying circuit 3 is provided to input the output of the voltage detecting circuit 1 and the output of the incoming signal detecting circuit 2. When the incoming signal detecting circuit 2 detects the signal and the voltage detecting circuit 1 detects the bottom voltage showing the opened loop state, the call signal identifying circuit 3 identifies the signal as the terminal equipment call signal. Thus, without the malfunction, the call signal and the dial pulse signal can be discriminated in an extremely short time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for detecting a ringing signal to terminal equipment such as a telephone, and particularly to a method for detecting a ringing signal to terminal equipment such as a telephone, and particularly to a method for detecting a ringing signal for a terminal equipment such as an answering machine using a dial pulse signal from terminal equipment connected in parallel. The present invention relates to a method for detecting a terminal equipment call signal, which is useful for preventing erroneous incoming signals, preventing resonance in cordless telephones, etc.

[Prior art] Conventionally, when terminal equipment such as multiple dial type telephones are connected in parallel, or when terminal equipment such as dial pulse type cordless telephones that can transmit and receive calls with both the base unit and the slave unit are used. In this case, a 75 V, 16 Hz terminal equipment calling signal is applied to the telephone line from the exchange that calls the terminal equipment, and a 10 pulses per second method or 20 pulses per second is applied to the telephone line by dialing from one terminal equipment. Since it is necessary to identify the dial pulse signal of the system, various terminal equipment call signal identification circuits are provided in terminal equipment such as telephones.

The first detection method using the conventional terminal equipment calling signal identification circuit is as follows: 1. Normally, the peak voltage of the calling signal is higher than that of the dial pulse signal.

A calling signal identification circuit is provided in which the load impedance and input sensitivity are set so as to respond only to the calling signal without responding to dial pulse signals transmitted from other terminal equipment connected in parallel.

The second detection method focuses on the difference in frequency and signal application time between the ring signal and the dial pulse signal, and digitally detects this difference. This is to identify whether it is a dial pulse signal.

[Problems to be Solved by the Invention] However, in the first conventional detection method for the terminal equipment call signal described above, the condition of the telephone line (for example, when the distance between the central office exchange and the terminal equipment is close) In some cases, the inductance and capacitance can cause a pulse of several hundred volts to be superimposed on the dial pulse signal, and the peak voltage of the dial pulse signal can be greater than the boundary voltage that identifies it as a ringing signal. Furthermore, if the distance from the central office exchange is long and a plurality of terminal equipment are connected in parallel, the ringing signal may attenuate and fall below the boundary voltage. In other words, in the first detection method described above, even if another terminal equipment connected in parallel receives a call due to the transmitted dial pulse signal, or a ringing signal arrives, the ringing tone is not recognized as the ringing signal. This caused terminal equipment to malfunction, such as not ringing.

Furthermore, in the second conventional detection method for a terminal equipment call signal, a certain amount of time is required from when the signal is applied to the telephone line until it is determined whether the signal is a call signal or not. In other words, when dialing the telephone number "0" at a dialing speed of 20 pulses per second, the telephone number "0"
" is expressed by 10 pulses, so it takes 0.5 seconds to finish transmitting the telephone number "0", and in addition to this 0.5 seconds, time for identification is also required. It is. Therefore, for about 0.5 seconds from the moment a signal is applied to the telephone line, it is not possible to determine whether or not this signal is a ringing signal. There is no sound, or other terminal equipment connected in parallel has a signal of about 0.5 even though it is a dial pulse signal.
There was an inconvenience in that the ringer would ring for a second.

The present invention was devised to solve the above-mentioned inconveniences, and the present invention has been devised to solve the above-mentioned problems. It is an object of the present invention to provide a method for detecting a terminal equipment calling signal, which does not cause malfunctions and is capable of distinguishing between a calling signal and a dial pulse signal in an extremely short time.

[Means for Solving the Problems] The above-mentioned problem is to detect the voltage applied to the telephone line, identify whether the telephone line is in a closed loop state or an open loop state, and output a voltage. a detection circuit, an incoming signal detection circuit that detects a signal applied to a telephone line and outputs that the signal is applied, and a call input to which the output of the voltage detection circuit and the output of the incoming signal detection circuit are input. a signal identification circuit, and when the incoming signal detection circuit detects a signal and the lowest voltage detected by the voltage detection circuit is a voltage indicating an open loop state, the calling signal identification circuit recognizes the signal from the terminal equipment. The problem is solved by a method for detecting a terminal equipment call signal, which is characterized by distinguishing it from a call signal.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

1 and 2 show an embodiment of the present invention,
FIG. 1 is a block circuit diagram, and FIG. 2 is a flowchart showing a method for detecting a terminal equipment call signal according to the present invention.

In this embodiment, an answering machine with an automatic facsimile switching function equipped with a method for detecting a terminal equipment call signal according to the present invention will be described. A dial pulse type telephone (not shown) is connected in parallel to the telephone of this embodiment.

1 is the telephone line L1. 2 is a voltage detection circuit for identifying the closed-loop state or open-loop state of L; 2 is a telephone line;
An incoming signal detection circuit 3 that detects an alternating current or pulsed signal applied to the telephone line L, receives the outputs of the voltage detection circuit 1 and the incoming signal detection circuit 2, and detects an alternating current or pulsed signal applied to the telephone line L. This is a ringing signal identification circuit that identifies whether a signal received by the telephone is a ringing signal or not, and if the telephone is in the at-home mode, it outputs an output to the ringing tone generation circuit 4 to generate a bell sound, and if the telephone is in the away mode, it outputs a ringing signal to generate a ringing sound. While closing the hook switch 5, the facsimile automatic switching circuit 6 and the answering machine circuit 7 are connected.
This is what drives the.

8 is a telephone line 1. A bridge rectifier circuit always outputs a DC voltage of a constant polarity even when the polarity of the DC voltage applied to L2 is reversed, 9 is a speech network that controls input and output of audio signals, and 10 is a handset.

Here, the modes of the telephone line 41L and TLZ in the closed loop state and the open loop state will be explained.

First, when the handset 10 is put down and the telephone is in standby mode, the DC loop between the central office exchange (not shown) and the telephone is open, and the DC voltage across the telephone line L2 at this time is is 42V to 53V. When one exchange calls a telephone, the above-mentioned DC4
A 75V, 16Hz AC signal is superimposed on 2 to 53V and transmitted.

On the other hand, when the handset 10 is picked up to make a call and the hook switch 5 is closed (on), the DC loop between the central office exchange and the telephone is closed, and the telephone line L1. The DC voltage between L and L drops to become a closed loop voltage. This closed-loop voltage is defined as the open-loop voltage when the DC loop is open, which is 48V, and the impedance of the dial pulse telephone, which is specified as 50Ω to 300Ω, to the maximum 300Ω.
Furthermore, if the impedance due to the length of the line from the central office exchange, which is 260Ω per 1-, is set to the minimum 0Ω,
The maximum voltage is approximately 28V, and the closed loop voltage is approximately 28V.
It never exceeds 8V. When a dial pulse signal is transmitted in this closed loop state, the DC voltage is intermittent between the closed loop voltage and the open loop voltage at a rate of 10 pulses per second or 20 pulses per second.

Hereinafter, a method for detecting a terminal equipment call signal according to the present invention will be explained based on the flowchart shown in FIG.

First, when an alternating current or pulse signal is applied to the telephone line L, the incoming signal detection circuit 2.

The first falling edge of the signal is detected and a signal indicating that the signal has been input to the calling signal identification circuit 3 is outputted.

Further, the voltage detection circuit 1 is connected to the telephone line L1. While monitoring the signal obtained by rectifying the signal applied to L by the bridge rectifier circuit 8, the maximum value of the closed loop voltage, approximately 28 V, is set as the boundary voltage (the voltage value can be freely set). If a signal larger than about 28V is detected, it is determined that the telephone line L□gLX is in an open loop state, and a signal indicating that it is in an open loop state is output to the calling signal identification circuit 3.

Then, upon receiving the output indicating that a signal has been input from the incoming signal detection circuit 2, the ringing signal identification circuit 3 starts to receive a signal from the voltage detection circuit 1 indicating whether or not it is in an open loop state. The voltage detection circuit 1 continues to receive the signal indicating whether the open loop state is established or not until it receives an output from the voltage detection circuit 2 indicating that the fall of the next signal has been detected.

However, if a signal indicating an open loop state is output from the voltage detection circuit 1 between the detection of the first falling edge and the detection of the next falling edge of the signal from the incoming signal detection circuit 2, that is, the voltage When the lowest voltage detected by the detection circuit 1 is higher than about 28V, which is set as a boundary voltage for identifying open loop state or closed loop state, the signal is determined to be a terminal equipment calling signal. Further, if the voltage detection circuit 1 does not output a signal indicating that the signal is in an open loop state between the detection of the first falling edge and the detection of the next falling edge of the signal from the incoming signal detection circuit 2, that is, the voltage detection circuit When the lowest voltage detected by the terminal 1 is smaller than about 28V, it is determined that the signal is a non-calling signal such as a dial pulse signal from terminal equipment connected in parallel.

Then, the calling signal identification circuit selects the telephone line L0. L2
When the signal applied to the terminal is identified as a terminal equipment ringing signal, the ringing tone generation circuit 4 is activated to produce a bell sound, and when the handset 10 is picked up and the hook switch 5 is turned off-hook, the speech network 9 determines the call state. Become.

In addition, if the home/absence mode selector switch (not shown) of the answering machine with facsimile automatic switching function of this embodiment is set to the absent mode, and the hook switch 5 is not off-hook after a predetermined number of rings, the telephone line L engineering,
After closing L2, the answering machine line 7 sends out the prerecorded response content, and then records the message. If it is determined that the calling party wishes to send a facsimile while the telephone answering machine line 7 is responding, the automatic facsimile switching circuit 6 switches the telephone line L2 to a facsimile machine (not shown) to receive the facsimile.

According to the above-mentioned method of detecting the calling signal, the telephone line L1
．． When a 167 call signal is applied to L, it can be identified as a call signal within one period of the rectified 161 (z signal, that is, 0°0625 seconds).

Furthermore, when a dial pulse signal is transmitted from terminal equipment connected in parallel, the voltage detection circuit 1 detects that the voltage is a closed loop voltage at the first falling edge of the dial pulse signal. The ring tone generation circuit 4 is not operated at all and is maintained in a standby state.

Furthermore, in order to make calls from terminal equipment connected in parallel,
When the handset is picked up and the telephone line is closed, L2 is closed, the incoming signal detection circuit 2 in this embodiment detects a fall from the open loop voltage to the closed loop voltage and outputs that there is a signal input. However, at this falling time, the voltage detection circuit 1 identifies that the telephone lines L and L2 are in a closed loop state, so the ringing signal identification circuit 3 identifies the signal caused by the falling as a non-ringing signal, Ringing tone generation circuit 4
It should not be activated.

In this embodiment, the case where the incoming signal detection circuit 2 detects the falling edge of the signal has been described, but of course the same effect can be achieved even if the incoming signal detection circuit 2 detects the rising edge of the signal. It is something to do.

In addition, in this embodiment, as a trigger for the calling signal identification circuit 3 to finish receiving the signal from the voltage detection circuit 1 indicating whether or not it is in an open loop state, the two signals from the incoming signal detection circuit 2 are used.
Although the second signal was used, as another method, a timer may be provided in the calling signal identification port 13. In this case, the time constant of the timer is 62.511 seconds as the longest time for one wavelength in the calling signal. It's good.

[Effects of the Invention] As detailed above, according to the method for detecting a terminal equipment call signal of the present invention, the electrical condition of the telephone line, such as the length of the distance from the central office exchange and the number of terminal equipment connected in parallel, etc. Regardless,
In addition to reliably distinguishing between incoming ringing signals and dialing pulse signals from terminal equipment connected in parallel to prevent malfunctions, the ringing signals and dialing pulse signals can be distinguished in an extremely short time. It is possible to eliminate inconveniences such as the ringing tone not sounding for a certain period of time even though a call has been received, or the terminal equipment connected in parallel ringing for a certain period of time even though it is a dial pulse signal. It is.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of an answering machine with an automatic facsimile switching function using the terminal equipment call signal detection method of this embodiment, and FIG. 2 is a flowchart showing the detection method of this embodiment. 1... Voltage detection circuit 2... Incoming signal detection circuit 3
...Call signal identification circuit patent

Claims (1)

[Claims] A voltage detection circuit detects the voltage applied to the telephone line to identify and output whether the telephone line is in a closed loop state or an open loop state, and a voltage detection circuit detects a signal applied to the telephone line. an incoming signal detection circuit that outputs that a signal has been applied, and a ringing signal identification circuit that receives the output of the voltage detection circuit and the output of the incoming signal detection circuit; Terminal equipment calling signal characterized in that when the lowest voltage detected by the voltage detection circuit is a voltage indicating an open loop state, the calling signal identification circuit determines the signal as a terminal equipment calling signal. Detection method.