JPS61252737A - Busy tone detector - Google Patents

Abstract

PURPOSE:To attain the detection of busy tone by constituting the titled detector with a filter circuit outputting a frequency component forming a busy tone from the signal of a telephone line, a conversion circuit converting the signal from the filter circuit and a control circuit outputting a signal representing the busy tone. CONSTITUTION:When a telephone set makes a call, a sent signal is inputted to the filter circuit 1. When a frequency component around 400-500Hz is inputted from a telephone line to the filter circuit 1, it is outputted to cut off the other frequency component. A conversion circuit 2 acts like a circuit outputting a high level signal when the frequency component around 400-500Hz is inputted from the filter circuit 1 for the time and outputting a low level signal when non input given thereto. A microprocessor 3 being a control circuit receives the signal converted in this way from the telephone line at its port so as to discriminate a busy tone from signals other than the busy tone and a noise from a call tone and to output a signal representing the busy tone as well as a signal representing the call tone. Thus, the busy tone is detected.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a redial function that automatically re-calls multiple times until the other party answers when the other party's terminal is busy in facsimile, data communication, etc. using a telephone line. The present invention relates to a busy sound detector that can be suitably used for busy detection, etc.

(Prior art) In data communication, etc., when a call is made to call the other party, a busy tone is returned if the communication is busy, and a ringback tone, that is, a ringing tone is returned if the call is not busy. .

If the other party's terminal is busy, it is necessary to cancel the call and try again.

It is common for data communication devices to have a long-dialing function, and as mentioned above, if the other party is busy, the first call is immediately canceled and the call is resumed after a certain period of time. .

(Object of the Invention) An object of the present invention is to provide a busy tone detector suitable for realizing the above-mentioned number-dial function.

(Means for Solving the Problems) In order to achieve the above object, a busy tone detector according to the present invention includes a filter circuit that outputs a frequency component forming a busy tone from a signal from a telephone line, and a filter circuit that outputs a frequency component forming a busy tone from a signal from a telephone line. a conversion circuit that converts the signal from the circuit so that the signal is at a first level when the frequency component forming the busy sound is outputted and is at the second level when the frequency component forming the busy sound is not outputted; When the output is monitored and a change point from the first level to the second level is detected, the change point from the second level to the first level is monitored, and when this is detected, time measurement is started, When the change point from the first level to the second level is detected again, it is determined whether the measured time of the first level state until this point is detected is greater than or equal to the value of X, and if it is less than or equal to the value of It is judged as noise, and if it is greater than the value of X, then the next second
Monitor the change point from the first level to the next second level.
When a change point from the level to the first level is detected, it is determined whether the measured time from when the change point from the second level to the first level is first detected is greater than or equal to the value of Y, and the value of Y is determined. In the above cases, it is determined that it is a ringing tone and outputs a signal indicating it.
If it is less than the value of Y, time measurement is restarted and the next change point from the first level to the second level is monitored, and when this is detected, the time measurement is restarted.
When the measurement time of the level state is less than or equal to the value of X, it is determined to be noise, and when it is greater than or equal to the value of X, the control circuit outputs a signal indicating a busy sound.

(Example) Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a busy tone detector according to the present invention. By making a call from a telephone (not shown),
The returned signal is input to the filter circuit 1.

The filter circuit 1 has characteristics as shown in FIG. 2, and when a frequency component around 400 to 500 Hz is input from the telephone line, it outputs it and operates to block other frequency components. If the filter circuit 1 is set to such a frequency characteristic, the busy sound will be heard within Japan (NTT).
) uses a frequency of 400 Hz, while in the United States a frequency around 450 Hz is used, and there are also cases of dual tone.

The filter characteristics shown in FIG. 2 are set to be applicable to all of these.

The conversion circuit 2 converts the output of the filter circuit 1 into a first level and a second level.
This is a circuit that converts the level, in this example, the first level and the second level.
Each level is associated with a high level and a low level. When a frequency component around 400 to 500 Hz is input from the filter circuit 1, it operates to output a high level signal only during that time, and to output a low level signal when there is no input.

The microprocessor 3, which is a control circuit, accepts the signal from the telephone line converted in this way to PORT (PORT), and distinguishes between busy tone and non-busy tone, noise, ring tone, etc. and outputs a signal indicating a busy tone as well as a signal indicating a ring tone.

FIG. 3 shows the circuit configuration of the microprocessor 3 in the form of a flowchart.

FIG. 6 shows an example of the waveform of the busy tone, and FIG. 7 shows an example of the waveform of the ringing tone. The configuration of FIG. 3 will be explained with reference to these figures as well.

Judgment operation starts when a signal is input from the conversion circuit (Step 10. However, this number is only used to identify the step, and the following has the same meaning and only numbers are written). , the busy tone break detection (11) is performed (Fig. 6 ■). When a break is detected, the meter is monitored, and when it is detected, a timer is started to measure the holding time of the meter state and one cycle of ringing (holding time of the meter state + holding time of the break state). (Figure 6 ■). The former determines whether it is greater than or equal to Xms, and the latter determines whether or not it is greater than or equal to Ysec. The break is then monitored (13) and detected (
Figure 6 (■) shows the holding time of the meter status, so if it is above Xm5ec, move on to the next meter monitoring (1
5). If it is less than Xmsec, it is judged as noise,
The process returns to break detection (11). When the meter is detected in (15) (Fig. 6 ■), it is then determined whether or not it is greater than or equal to Ysec (16), and if it is less than Ysec, the timer is started again (17) and further break monitoring is performed. (18) (Figure 6 ■). On the other hand, if it is Ysec or more, it is determined that it is a ringing tone and a signal indicating it is output (
21) (Figure 7).

When a break is detected in (18), the holding time of the next make state is known, so if it is Xm5ec or more, a signal indicating a busy tone is output (19.20).

If it is less than Xm5ec, it is determined to be noise, and the process returns to break detection (11). This signal indicating the busy tone is used as a busy indication or as a signal for on-hooking the telephone line.

FIG. 4 is a more specific version of the configuration shown in the flowchart of FIG. 3, and shows the flow according to the program of the microprocessor 3, which is a control circuit.

FIG. 5 is an example of the definition of flags used in the flow of FIG. 4. The flag consists of 8 bits, and flag bo is set when the first break is detected.

Upon detection of the next meter, flag b1 is further set, and thereafter, upon detection of the second break and second meter, flag b2. b3 will stand.

b7 is a flag that is set when a ringing tone is detected.

When the program starts (30), the flag is cleared (31), so flag b7. bo's judgment (32, 33
), the break is first determined (34
). If no break is detected, 60 loops will be repeated. Flag b when a break is detected
o stands (35), passes through (32, 33, 36), and the meter is judged (37). If the meter cannot be detected, the process returns without setting the flag b1. When the meter is detected, the flag b1 is set and the timers Xm5ec and Ysec are set (3B, 39.40), so (32, 3
3, 36, 41), and a second break determination is made (42). If a break cannot be detected, the process returns without setting flag b2. When a break is detected, Xm
A determination is made as to whether or not it is 5ec or more (43),
If it is more than m5ec, flag b2 is set and Xm5e
If it is less than c, it is determined to be noise, and all flags are cleared (44.45). Next, each flag determination is passed by the flag b2 as described above, and the second meter determination is performed (47). If the meter is not detected, the flag b3 is not set; when the meter is detected, it is then determined whether or not it is Ysec (48), and if the meter is greater than or equal to Ysec, the flag b7 is set (51). On the other hand, if it is less than Ysec, the timer is set again and flag b3 is set (4
9,50). If the flag b7 is set, the determination in (32) is affirmed, and therefore it is determined that it is a ringing tone (56). If flag b3 is set (32, 36, 41, 46
), and the third break is determined (52)
. If a break cannot be detected, no flag is set, and if a break is detected, it is determined again whether or not it is greater than or equal to Xm5ec (53), and if it is less than Xm5ec, it is determined to be noise and all flags are set. Cleared (5
4). Also, if the signal is Xm5ec or higher, it is only at this point that it is determined to be a busy tone (55).

(Effects of the Invention) As explained above in detail, the present invention is composed of a filter circuit, a conversion circuit, and a control circuit, and the filter circuit extracts the frequency component forming the busy sound, and the conversion circuit extracts the frequency component that forms the busy sound, and the conversion circuit recognizes the frequency component in the control circuit. The busy tone can be detected by replacing the waveform with a possible waveform format, detecting the changing points of the waveform, and determining the time between the changing points using a program.

The output of this busy tone detector can be used as is as a signal for displaying the busy tone, and as explained at the beginning, it can be used as part of the redial function to connect the busy tone detection output to the on-hook operation. It is also possible.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of a busy sound detector according to the present invention, FIG. 2 is a diagram showing frequency characteristics of a filter circuit, FIG. 3 is a flow chart for explaining the configuration of a microprocessor, and FIG. Figure 4 is a diagram showing the flow of a microprocessor program. FIG. 5 is a diagram showing an example of a flag configuration, FIG. 6 is a waveform diagram showing an example of a busy tone, and FIG. 7 is a waveform diagram showing an example of a ringing tone. 1... Filter circuit 2... Conversion circuit

Claims (1)

[Claims] a filter circuit that outputs a frequency component forming a busy tone among signals from a telephone line; and a signal from the filter circuit is set to a first level when the frequency component forming a busy tone is outputted; A conversion circuit that converts when no output is output to the second level, and monitors the output from the conversion circuit, and if a change point from the first level to the second level is detected, then the second level The change point from the first level to the first level is monitored, and when this is detected, time measurement is started, and when the change point from the first level to the second level is detected again, the first Determine whether or not the measurement time of the level state is greater than or equal to the value of X. If it is less than or equal to the value of
Monitor the change point from the first level to the next second level.
When a change point from the level to the first level is detected, it is determined whether the measured time from when the change point from the second level to the first level is first detected is greater than or equal to the value of Y, and the value of Y is determined. In the above cases, it is determined that it is a ringing tone and outputs a signal indicating it.
If it is less than the value of Y, time measurement is restarted and the next change point from the first level to the second level is monitored, and when this is detected, the time measurement is restarted.
Busy sound detection characterized by comprising a control circuit that determines noise when the measurement time of the level state is less than or equal to the value of X, and outputs a signal indicating busy sound when it is greater than or equal to the value of X. vessel.