JPH03276948A - Automatic answering telephone set - Google Patents

Abstract

PURPOSE:To realize an automatic answering telephone set by which a lockout tone is quickly detected by opening a line when it is confirmed and discriminated that a prescribed measured value satisfies the standard of the lockout tone signal generated by an exchange. CONSTITUTION:The telephone set is provided with a signal level measuring section 6 measuring a level of a signal appearing on a line, a timer 9 measuring on/off length of a voice signal and a zero cross counter 7 counting number of zero cross appearing on the line and a control section 8, which uses a timer 9 to measure the on-time length and the off-time length of the voice signal in message recording after automatic dialing, uses a measuring section 6 to measure the signal level in the on-period, uses a counter 7 to measure the zero cross number for the on-period so as to discriminate whether or not four measured values satisfy the standard of the lockout tone signal generated by an exchange and to discriminate the end of talking by the caller when the measured value satisfies the standard to open the line. Thus, the invalid acquisition time of the line is shortened by the detection with high accuracy in this constitution.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides an answering machine with a message recording function when the caller ends the call without recording the message, or when the caller ends the call without recording the message. Even if you start recording the message, if the caller finishes speaking the message and ends the call before the answering machine releases the line due to timeout, it will be detected that the caller has ended the call. The present invention relates to end-of-call detection technology for shortening the time that an answering machine is holding a line as invalid by releasing the line.

[Prior art] When an answering machine automatically receives a call and starts automatic answering operation,
Callers often do not expect an answering machine to answer. In this case, the caller is confused by the response message on the answering machine, and at the same time, the caller does not send the message due to the hassle of having to discuss the matter in a short time and the discomfort of talking to a machine. There are very few cases where the caller ends the call without recording it. When the caller ends the call, the answering machine also disconnects the line to shorten the time the answering machine holds the line invalidly. need to be released quickly.

Normally, when one party ends the call and releases the line during a call, a lockout tone is sent from the exchange to the other party's line. Many answering machines use this lockout tone to detect when the caller has hung up.

FIG. 5 shows an example of a lockout tone detection circuit used in a conventional answering machine.

Hereinafter, the principle of lockout tone detection using this circuit will be explained with reference to FIG. In Figure 5, R3-R3 is a resistor, Co-C is a capacitor, Q is a transistor, and M
V is a one-shot multi-bye break.

When a signal is applied to the input terminal, the base potential of transistor Q increases. When the input signal is large and the base-emitter voltage exceeds a certain value, the transistor Q becomes conductive, triggering the one-shot multi-vibration break MV and generating a pulse at the output terminal. This pulse is shown in FIG. 6(a).

As shown in (b), this occurs only at the rising edge of the input signal. As shown in FIG. 6(a), a constant period like a lockout tone (Ta l= Ta t= Ta
m, T b l = T b ll), the output pulse also has a constant period (To + = TOX)
However, as shown in FIG. 6(b), when an audio signal such as a human voice is input, the output pulse period is not constant. Since the period of the lockout tone is a known value, the output pulse period is monitored, and when it matches the lockout tone period, the input signal is determined to be a lockout tone.

[Problem to be solved by the invention]

However, in the conventional lockout tone detection circuit shown in Fig. 5, detection is performed based only on lockout tone period information, so it is possible that the caller's speaking period coincidentally coincides with the lockout tone period. If this happens, it may be mistakenly detected as the end of the call. In this case, a situation arises in which the line is opened even though the call has not actually ended.

To avoid this situation, in order to reliably detect only the lockout tone, current answering machines require a long period of time equivalent to 6 to 10 periods of the lockout tone to output the one-shot multivibrator MV shown in Figure 5. monitor,
A method is used in which the arrival of a lockout tone is confirmed for the first time when the cycle conditions match continuously during this monitoring time, and the line is released. As a result, it takes time to detect the lockout tone, resulting in a long line invalid acquisition time.

The present invention was made in order to solve the above-mentioned problems, and it is an object of the present invention to provide an answering machine that can quickly detect a lockout tone.

[Means for Solving the Problems] An answering machine according to the present invention includes a signal level measurement unit that measures the level of a signal appearing on a line, and an audio signal output unit that measures the level of a signal appearing on a line.
N. It has a timer that measures the OFF length and a zero-crossing counter that counts the number of zero-crossings of the signal appearing on the line. The signal level during the ON period is measured by a signal level measurement unit, and the number of zero crossings during the ON period is measured by a zero crossing counter.The above four measured values are the lockout tone signal generated by the exchange. [Operation] This invention is equipped with a control unit that determines whether or not the standard is satisfied, and when it is confirmed that the standard is satisfied, it is determined that the caller has completed the call and the line is released. Since the number of types of information used to determine the arrival of a lockout tone is four, the probability that a caller's utterance is mistakenly determined as a lockout tone is low. Therefore, it is possible to reduce the lockout tone period used to confirm the arrival of the lockout tone, and as a result, the time required to acquire an invalid line when the caller abandons the call while recording a business message can be reduced. I can do it.

〔Example〕

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In this figure, 1 is a call signal detection unit that detects the arrival of a call signal on the line, 2 is a loop opening/closing unit that opens and closes the line, and 3 is a call signal that is connected to the line via the loop opening/closing unit 2. 4 is a response message sending unit connected to the transmitting (T) terminal of the telephone call circuit 3; 5 is a business message recording unit connected to the receiving terminal (R) of the telephone call circuit 3; 6 is a loop opening/closing unit 2; 7 is a zero crossing counter connected to the line via the loop opening/closing unit 2, 8 is a control unit, and 9 is a line signal ○N10.
This is a timer for measuring FF time. It is assumed that the timer 9 automatically counts the time from zero upon receiving an instruction from the control section 8 to reset the timer count.

FIG. 2 shows a specific configuration of the signal level measuring section 6 and an example of its interface with the control section 8. In Figure 2, Rz~R+s
is a resistor, C is a capacitor, and Dl.

D2 is a diode, OPI, OR3 is an operational amplifier, and 6A is an A/D converter. In this circuit example, the operational amplifier OPI and the surrounding diodes D,
A half-wave rectifier circuit is constructed by D, and the operational amplifier OP2 and its surrounding capacitor C1 resistor R11l
A low-pass filter is constructed. At this time, the output of the operational amplifier OP2 becomes the envelope of the input signal. This envelope is converted into a digital signal by the A/D converter 6A, and is input to the control section 8 at regular intervals.

FIG. 3 shows the specific configuration of the zero crossing counter 7 and the control section 8.
This is an example of an interface with In this figure, R,,,R,
□ is a resistor, OR3 is an operation amplifier, 7A is U
It is a P counter. The operational amplifier OP3 functions as a zero-crossing detector, and outputs a rectangular wave that rises or falls when the input signal crosses the zero level and corresponds to the zero-crossing. The UP counter 7A counts and the control unit 8
reads the count value at regular intervals. Note that the count value is reset when the control unit 8 reads the count value.

FIGS. 4(a), 4(b), and 4(c) are flowcharts illustrating the operating procedure in the configuration of FIG. 1. below,
The operation of the embodiment of the present invention will be explained with reference to FIG. Note that S1 to S12. S21 to S25 and S-31-333 indicate each step.

As shown in Figure 4(a). When a calling signal arrives on the line, the calling signal detection section 1 detects it (Sl). When the control unit 8 sufficiently confirms that the number of rings continues for a certain number of times or more and that a ringing signal has arrived (for example, after 2 to 3 ringing signals), it operates the loop opening/closing unit 2 to close the line ( S2)
. When the line is closed, the response message sending unit 4 is operated to send a response message to the line via the telephone call circuit 3 (S3). When the sending of the response message is completed, the business message recording unit 5 starts recording the line signal via the telephone call circuit 3 (S4). At the same time, the control unit 8 resets and starts the timer 9 (S5) and starts ON period length measurement processing (S6).

In the ON period length measurement process, the control section 8 controls the signal level measurement section 6. Data from the zero crossing counter 7 is read at regular intervals. Note that the data reading cycle is sufficiently short compared to the lockout tone transmission cycle. Timer 9 will also measure the duration of the signal that is determined to be the lockout tone period, as will be explained below. Hereinafter, the operation of the control section 8 in the ON period length measurement processing device will be explained based on FIG. 4(b).

Line signal level V read from signal level measuring section 6
in is compared with level thresholds Vl and V2 (S2
1,522). Level threshold V1. ■2 is set in advance so that the level of the lockout tone ON period measured by the signal level measuring section 6 falls between Vl and V2, taking into account variations in the lockout tone transmission level of the exchange and subscriber line loss. I'll keep it. Now, signal level measurement section 6
The read value Vin from
) is satisfied. At this time, the control unit 8 compares the read value Zin from the zero crossing counter 7 with zero crossing number thresholds Zl and Z2 (S23). The zero crossing number thresholds Zl and Z2 are the lockout tone O transmitted by the exchange.
Considering the variation in the signal fundamental frequency during the N period,
O of the lockout tone measured by zero crossing counter 7
The number of zero crossings in the N period is set to fall between Zl and Z2. When formula (1) holds true, Z1≦
When Zin≦Z 2 ····+21 holds true, both the level condition and the frequency condition of the lockout tone ON period signal hold, so it can be determined that the lockout tone ON period signal has arrived. The timer 9 continues counting until it is determined that the ON period of the signal has ended, that is, until equation (3) is satisfied.

V in < V 1 =
-(3) When the formula (3) is satisfied, the count value of the timer 9 is stored in the variable Ton (S24). In addition, before the duration measurement middle cylinder (3) formula is established, V2<Vin ・・・・・・(
4), or if equation (2) is no longer satisfied, it can be determined that the incoming signal is not a lockout tone, so the timer 9 is reset (S25).

As a result, the ON period length measurement processing timer 9 counts the duration of the signal that is determined to be the lockout tone ON signal. The measured Ton is compared with time thresholds Tonl and Ton2. Time threshold To
ol, Ton2 is set by the control unit 8 in consideration of the variation in the ON period duration of the lockout tone sent by the exchange.
The lockout tone ON period duration measured at T
Set it so that it falls between ool and Ton2 (.Now, for the measured Ton, Tonl≦Ton≦T on 2 − ・=
When it is confirmed that (5) holds true (S7),
During this ON period, the three conditions of the level condition, the frequency condition, and the duration condition are satisfied, and it can be determined that this is the lockout tone ON period. Therefore, after resetting the timer 9 (S8), the OFF period length measurement process is started (S9). If formula (5) does not hold,
Since it cannot be determined that it is the lockout tone ON period, after resetting the timer 9, the ON period length measurement process is terminated. This concludes the explanation of the ON period length measurement process.

During the OFF period length measurement process, the timer 9 measures the duration of the OFF state of the line signal, as shown in FIG. 4(C). The control unit 8 monitors whether equation (3) holds true for the output Vin of the signal level measurement unit 6 (S
31,532). If the equation (3) is not satisfied, the value of the timer 9 is stored in the variable Toff, and the OFF period length measurement process is ended (S33).

The value of T off is determined by the time threshold T offl, T
It is compared with off2. T offl, T off2
T off
, Toff2. now,
For the measured Toff, Toffl≦Toff≦Toff2 −
- When (6) is established (SIO), four types of lockout tones are established: ■ Level condition of ON period, ■ Frequency condition of ON period, ■ Duration length of ON period, ■ Duration length of OFF period. The information has been confirmed,
It can be determined with high probability that the lockout tone has arrived. At this time, it can be determined that the caller has ended the call, so the control unit 8 stops the recording operation of the message recording unit 5 (Sll), and then operates the loop opening/closing unit 2 to open the line and operate. The process ends (S12). No. (6)
If the formula does not hold, reset timer 9 and turn O again.
Execute N period length measurement processing. Note that if the message recording area of the message recording unit 5 becomes full during processing after the start of message recording, the line is released and the operation ends without waiting for the caller to speak. .

[Effects of the Invention] The present invention includes a signal level measurement unit that measures the level of a signal appearing on a line, a timer that measures the ON/OFF length of an audio signal, and a timer that counts the number of zero crossings of a signal that appears on a line. It has a zero-crossing counter, measures the ON time length and OFF time length of the audio signal with a timer while recording the business message after automatic call reception, and measures the signal level during the ON period with a signal level measuring section, The number of zero crossings during the ON period is measured using a zero crossing counter, and
A control unit that determines whether or not the measured value satisfies the standards for the lockout tone signal generated by the exchange, and if it is confirmed that the measured value satisfies the standards, determines that the caller has completed the call and releases the line. Since the lockout tone is detected based on the characteristic information of the lockout tone, such as the duration of the 0N10FF period, the signal level during the ON period, and the signal fundamental frequency, it is possible to improve the detection accuracy. be. Therefore, unlike conventional end-of-call detection circuits, it is not necessary to input several periods of lockout tone to confirm that it is a lockout tone. Out tone input is sufficient.

For this reason, even if the caller releases the line before the answering machine releases the line when an automatic call is received, the time required to acquire an invalid line is reduced compared to when using a conventional end-of-call detection circuit. There is an advantage that it is possible to do so.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.
FIG. 2 is a diagram illustrating a specific configuration example of a line signal level measurement unit and an interface with a control unit, and FIG. 3 is a diagram illustrating a specific configuration example of a zero-crossing counter and an interface with a control unit. 4(a), (b), and (c) are flowcharts showing an example of the operation in the configuration of FIG. 1, FIG. 5 is a diagram showing an example of a conventionally used call end detection circuit, FIG. 6 is a diagram illustrating the relationship between input and output signals in the end-of-call detection circuit shown in FIG. 1, separately for when a lockout tone is input and when normal voice is input. In the figure, 1 is a ring signal detection unit, 2 is a loop opening/closing unit, 3 is a communication circuit, 4 is a response message sending unit, 5 is a message recording unit, 6 is a signal level measurement unit, and 6A is an A/D converter. , 7 is a zero crossing counter, 7A is an UP counter, 8 is a control unit, and 9 is a timer. Figure 2 Figure 2 Figure 2

Claims (1)

[Claims] A ringing signal detection unit and a loop opening/closing unit that detect a ringing signal from a line and automatically receive a call, a response message sending unit that sends a response message to the line after automatically receiving a call, and a response message that is sent via the line after the response message is sent. By having a business message recording unit that records the caller's voice,
In an answering machine that records the caller's message after sending a response message during automatic answering, a signal level measurement section that measures the level of the signal appearing on the line, and a timer that measures the ON/OFF length of the voice signal. , has a zero-crossing counter that counts the number of zero-crossings of the signal appearing on the line, and measures the ON time length and OFF time length of the voice signal with the above-mentioned timer while recording the business message after automatic call reception, and The signal level during the period is measured by the signal level measurement unit, and the number of zero crossings during the ON period is measured by the zero crossing counter, and the above four measured values satisfy the standards of the lockout tone signal generated by the exchange. An answering machine characterized by comprising a control unit that determines whether the caller has completed the call and releases the line when it is confirmed that the caller has completed the call.