JPH0214656A - Ring trip circuit - Google Patents

Abstract

PURPOSE:To attain stable operation regardless of the kind of a subscriber terminal equipment independently of the subscriber line length by varying a threshold value to discriminate reply/no reply in response to the length of the subscriber line. CONSTITUTION:The 1st sample-and-hold circuit 2 holds an output of a DC detection circuit 1 in no reply of a called party during the transmission of a called signal and the 2nd sample-and-hold circuit 3 holds an output of the DC detection circuit 1 at called party reply during the transmission of a call signal. A threshold value setting circuit 4 sets based on the outputs of the 1st sample-and-hold circuit 2 and the 2nd sample-and-hold circuit 3 a threshold value for proper called party reply detection corresponding to the length of the subscriber line. A discrimination circuit 5 compares the threshold value with the output of the DC detection circuit 1 to discriminate the reply/no reply of the called party. Thus, the stable operation without malfunction regardless of the kind of the subscriber terminal equipment independently of the length of the subscriber line is ensured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a ring trip circuit of a subscriber circuit used in an exchange, and particularly relates to a ring trip circuit of a subscriber circuit used in an exchange, and particularly relates to a ring trip circuit of a subscriber circuit used in an exchange. Ring that can operate stably) IJ
Regarding the Tsubu circuit.

[Conventional technology]

The conventional ring trip circuit is disclosed in Japanese Patent Application Laid-Open No. 61-19265.
As described in the above publication, a circuit is known in which a threshold value for determining a response/non-response for detecting a response of a called party is variable. In this conventional circuit, the threshold value of the response/non-response judgment circuit is determined by the output voltage of the DC detection circuit when the called party is not responding while the calling signal is being sent. Since it is set independently, the threshold value of the response/non-response determination circuit is fixed regardless of the subscriber line length.

[Problem to be solved by the invention]

In the above conventional technology, the threshold value of the response/non-response judgment circuit for detecting the response of the called party is determined by the output voltage of the DC detection circuit when the called party is not responding while the calling signal is being sent. Since the output voltage is constant regardless of the subscriber line length, the threshold value of the response/non-response determination circuit is also fixed regardless of the subscriber line length. However, when the called party answers while a paging signal is being sent, the output voltage of the DC detection circuit is large for short distances and small for long distances, so the response is fixed regardless of subscriber line length.・With respect to the non-response judgment threshold, the margin of the detection circuit output voltage in the case of a long distance is smaller than the margin of the detection circuit output voltage in the case of a short distance. There is a problem in that in the case of a distance, it is likely to be undetected, and in the case of a short distance, it is likely to be erroneously detected.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art described above and to provide a ring trip circuit that can operate stably regardless of the subscriber line length and regardless of the type of subscriber terminal.

[Means for Solving the Problems] The above object is to provide a DC detection circuit that detects a DC signal component superimposed on a ringing signal in order to detect a response from a called party, and a DC detection circuit that detects a DC signal component superimposed on a calling signal to detect a called party's response, and a DC detection circuit that detects a DC signal component superimposed on a calling signal to detect a called party's response. a first sample and hold circuit that holds the output of the DC detection circuit, a second sample and hold circuit that holds the output of the DC detection circuit when the called party responds, and the first sample and hold circuit and the second sample and hold circuit. a threshold value setting circuit for setting a threshold value for detecting a called party response corresponding to the subscriber line length based on the output of the circuit; and a threshold value for detecting a called party response based on the output of the threshold value setting circuit and the DC detection circuit. This is achieved by a ring trip circuit that varies a threshold value for detecting a called party response in accordance with the subscriber line length.

[Effect]

The first sample and hold circuit of the ring trip circuit holds the output of the DC detection circuit when the called party does not respond while sending the ringing signal, and the second sample and hold circuit holds the output of the DC detection circuit when the called party does not respond while sending the ringing signal. The output of the detection circuit is held, and the threshold value setting circuit sets a threshold value for detecting an appropriate called party response corresponding to the subscriber line length based on the output of the first sample and hold circuit and the output of the second sample and hold circuit. A determination circuit that determines whether the called party has not responded by comparing the threshold for detecting the called party's response output from the threshold setting circuit with the output of the DC detection circuit. Judgment of response Since the above-mentioned judgment circuit determines whether the called party responds or does not respond while the paging signal is being sent, the threshold value is set to be large when the distance is short, corresponding to the length of the subscriber line. In the case of long distances, it is made variable so that it becomes small, and the margin of the output of the DC detection circuit when a response is detected and when it is not detected for this appropriate threshold value and the internuclear value is both large (the margin for the output of the DC detection circuit when a response is detected and when it is not detected is Since it is possible to set an appropriate value such as (maximum when the margins are equal), stable operation that does not malfunction is ensured regardless of the subscriber line length and regardless of the type of subscriber terminal.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 is a block diagram showing an embodiment of a ring IJ tube circuit according to the present invention. In Figure 1/? ＋R
2 is a resistor, CR is a calling signal source, VRO is a DC power supply, r,
is a relay for sending out a calling signal, and is a telephone set. 1 is a DC detection circuit, 2 is a first sample and hold circuit, 3 is a second
A sample hold circuit, 4 a threshold setting circuit, and 5 a determination circuit. The resistor R2 for detecting the ringing signal current, the ringing signal source CR, the DC power supply VIIO, and the ringing signal current limiting resistor R1 shown in FIG. connected to send out a calling signal.

The ring trip circuit shown in FIG. 1 includes a DC detection circuit 1 for detecting a DC voltage component caused by a DC signal component superimposed on a ring signal from a voltage across a resistor R2 that detects a ring signal current, and a relay for sending a ring signal. r, a first sample and hold circuit 2 that uses the output of the DC detection circuit 1 during operation to hold the output of the DC detection circuit 1 when the called party does not respond; A threshold value for setting a threshold value for detecting a called party response corresponding to the subscriber line length using the second sample hold circuit 3 that holds the output, the output of the first sample hold circuit 2, and the output of the second sample hold circuit 5. It is comprised of a setting circuit 4 and a determination circuit 5 that compares the output of the threshold value setting circuit 4 and the output of the DC detection circuit 1 to determine whether the called party responds or does not respond while the calling signal is being sent.

FIG. 2 is a timing diagram showing the operation when the subscriber terminal in FIG. 1 is a general telephone device. The operation when the subscriber terminal shown in FIG. 1 is a general telephone device will now be described with reference to FIG. 2.

First, at time 1-1 in FIG. 2, when the ringing signal sending relay r is operated with the handset of the general telephone set not being picked up (on-hook state), the ringing signal current flows from the ringing signal source CR to the resistor R2 and the ringing signal. The signal flows through the sending relay r, the subscriber line, the general telephone equipment, the subscriber line, the calling signal sending relay r, and the transmission line R1. At this time, resistance R2
The voltage across the terminal is only the alternating current voltage due to the calling signal, and the output r of the direct current detection circuit 1 becomes zero (FIG. 2). The first sampling hold circuit 2 is connected to the output V of this DC detection circuit 1.
, and the output VON of the first sample and hold circuit 2 becomes zero.

At this time, the second sample and hold circuit 3 is connected to the DC detection circuit 1.
The second sample and hold circuit 3 does not take in the output V of
The output Vopy remains zero. The threshold value setting circuit 4 receives the output VON of the first sample and hold circuit 2, which is its input.
and the output Voyp of the second sample and hold circuit 3 are both zero, the preset reference threshold voltage V1Ha
(Figure 2). This reference threshold voltage VTHQ is the value that allows K ring tripping at the longest subscriber line length, that is, at a long distance.
and the threshold value setting circuit 40 output VTH and find that V+ > F
In the case of ry, the output V has one meaning, so in this case the output V.

is zero and VTII -VTHO, so the output V2 of the determination circuit becomes "meaningless" (FIG. 2).

Next, time 1-1 in FIG. When the called party picks up the handset of the general telephone device (off-hook), the DC impedance of the telephone stack becomes small, and the DC power supply Vna, the ringing signal source CR, the resistor R2, and the ringing signal sending relay r,
Since a DC loop is formed by the path of , the subscriber line, the telephone stack, the subscriber line, the calling signal sending relay τ, and the resistor R1, a DC signal component is superimposed on the calling signal. As a result, a composite voltage of the ringing signal voltage and the DC signal component voltage is generated across the resistor R2, and the output r1 of the DC detection circuit 1 changes to the output Vri (-) of the threshold setting circuit 4 at time twt.
Vrxo), the output r of the 1 judgment circuit 5,
becomes “meaningful”. Next, at time 1-1, a certain period of time has passed after the output r1 of the determination circuit 5 becomes “meaningful”.
4, the second sample and hold circuit 3 captures and holds the output Vl (-Vll) of the DC detection circuit 1, and outputs the output of the second sample and hold circuit 5 Voyy -Voypl (=
Vat ) (Figure 2). At this time, the output Fll of the DC detection circuit 1 differs in magnitude depending on the length of the subscriber line, and has a high value at short distances and a small value at long distances.

The output VOFF of the second sample and hold circuit 3 is from zero to J
'OFF+, the threshold setting circuit 4 outputs the output VON M O of the first sample hold circuit 2 which is its input.
and the output Vary −VO of the second sample and hold circuit 3
PPI (=Vu), the output VTI is set to an appropriate threshold value VTH+ according to the subscriber circuit length (FIG. 2). This threshold value VTH1 is determined by the following equation.

Vrxl-(Voyy+-o)xz+o (1
Also, the stock constant has an appropriate value of 1.

At this time, the output VTR of the threshold setting circuit 4, which is the input of the judgment circuit 5, changes from VTHO to VTH1, but since the output V11 of the DC detection circuit 1, which is the input thereof, is larger than VrH1, the output r of the judgment circuit 5 is It remains "meaningful" (Figure 2). Next, the called party's response is detected based on the output V of the determination circuit 5, ``meaningful'', and time 1=1. When the calling signal sending relay τ, stops sending out the calling signal to the general telephone equipment, the output r of the DC detection circuit 1
, decreases toward zero, so at time 1 = 1・V+
<Hrx +, the output Vt of the determination circuit 5 changes to "meaningless" (FIG. 2). After that, the output VON -0 of the first sample and hold circuit 2 and the output VOFF "' VOPPI of the second sample and hold circuit 3 continue to hold their values, and the output VTH-V of the threshold value setting circuit 4
THl is also fixed, and thereafter it operates to detect the called party's response only when the output V1 of the DC detection circuit 1 becomes larger than VTH1.

FIG. 3 is a characteristic diagram showing the relationship between the threshold value of FIG. 2 and the subscriber line length when the subscriber terminal of FIG. 1 is a general telephone device.

In FIG. 3, the output V++ of the DC detection circuit 1 in FIG.
(=Vopp+) changes depending on the subscriber line length, and takes a large value at short distances and a small value at long distances. The threshold value setting circuit 4 operates as explained in FIG.
After capturing and holding Voyp+), the output Vrt (= Voy
y+) to determine the appropriate threshold value VTH according to the subscriber line length.
I will be automatically set variable and output. By setting the constant K for setting this threshold value VTH+ using equation (1) to an appropriate value that is unlikely to malfunction, for example, 1/2, the output r of the DC detection circuit 1 with respect to the threshold value VTH+
, increase the margins when a response is detected and when it is not detected,
This enables a stable callee response detection operation that does not malfunction due to leakage current or noise such as AC induction, regardless of the subscriber line length.

FIG. 4 is a timing diagram showing the operation when the subscriber terminal in FIG. 1 is a special terminal. As shown in FIG. 4, when the subscriber terminal shown in FIG. 1 is not a regular telephone device but a telephone equipped with a cold cathode discharge tube and the called party is not responding while sending out a ringing signal, the output V of the DC detection circuit 1 becomes zero. The following describes the operation for special terminals that do not. First, time t m in Figure 4
When the special terminal is on-hook and the calling signal sending relay ry operates at t, the output V1 of the DC detection circuit 1 changes from zero to "It" (Fig. 4), and the first sample hold circuit 2 Output rl of DC detection circuit 1,
is captured and held, and the output VON of the first sample and hold circuit 2 becomes VON+ (-1"It) (Fig. 4). At this time, the output VQF of the second sample and hold circuit 5 becomes VON+ (-1"It).
F remains zero, and the threshold setting circuit 4 outputs the threshold output VT from the reference threshold voltage VTHO using the output VON=VON1 of the first sample and hold circuit 2 and the output VOIP"O of the second sample and hold circuit 3. VTH""
VTH2” VTHO+ Set to VON+ (4th
figure).

Next, time 1-1 in FIG. Smell [When the called party goes off-hook, a DC loop is formed and a DC signal component is superimposed on the calling signal, so that the output V1 of the DC detection circuit 1 is the output r1 at the time of on-hook! The value changes from the value obtained by adding the DC signal component voltage.

Then time 1-1. When the output V1 of the DC detection circuit 1 exceeds the output VTll = VTH2 of the threshold setting circuit 4,
The output V of the judgment circuit 5 changes from "meaningless" to "meaningful"
becomes. Then, at time 1 = 14, the second sample and hold circuit 3 takes in and holds the output "I-" In of the DC detection circuit 1, and outputs J'0 of the second sample and hold circuit 3.
7/ = Voyyz (-V's) (Figure 4)
. When the output VOFF of the second sample and hold circuit 5 changes from zero to VDFP2, the threshold setting circuit 4 changes the output VON of the first sample and hold circuit 2 and the second
Output of sample hold circuit 5 Vary -Voyyz
(-Vls), the output VTH is set to an appropriate threshold value VTH5. This threshold value VTH5 is determined by the following equation.

Vrys = (VOJIF2 Vopt+)
K + Voprl (2, but the constant is 0 × K × 1
is an appropriate value. Thereafter, as in the case of the general telephone device shown in FIG. 2, the time 1-1. When the calling signal sending relay T is restored by detecting the called party's response, and at time t, the output V of the output detection circuit 1 becomes less than the threshold output VTH5, the output V1 of the determination circuit 5 becomes "meaningless". Thereafter, the response of the called party is detected only when the output V1 of the DC detection circuit 1 becomes larger than the threshold output VTH5.

FIG. 5 is a characteristic diagram showing the relationship between the threshold value of FIG. 4 and the subscriber line length when the subscriber terminal of FIG. 1 is a special terminal. Fifth
In the figure, the output Vlt (
-Voxl) and the output '11 (-VO!!2) change depending on the subscriber line length, and are large at short distances and small at long distances. By making the outputs VTH2 and VTH3 variable according to the subscriber line length, it is possible to connect even in the case of special terminals in which the output V1 of the DC detection circuit 1 does not become zero when the called party does not respond while the calling signal is being sent. It is possible to perform stable detection of a called party response regardless of the length of the called party line.

〔Effect of the invention〕

According to the present invention, the DC detection circuit output when the called party does not respond while sending a ringing signal and the DC detection circuit output when the called party responds while sending the ringing signal are held, and from these two output voltages. Since the threshold value for determining whether the called party responds or does not respond can be appropriately set, the threshold value, which was conventionally set fixedly regardless of the subscriber line length, can be changed according to the subscriber line length. This has the effect of realizing a ring trip circuit that can operate stably without malfunctioning regardless of the subscriber line length and regardless of the type of subscriber terminal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the ring trip circuit according to the present invention, FIG. 2 is a timing diagram showing the operation when the subscriber terminal in FIG. 1 is a general telephone, and FIG. Figure 4 is a characteristic diagram showing the relationship between cable length and line length.
FIG. 5 is a timing diagram showing the operation when the subscriber terminal shown in the figure is a special terminal, and FIG. 5 is a characteristic diagram showing the relationship between the threshold value and the subscriber line length. 1 ・River・・・・・・・・・・・・ 2・・・・・・・・・・・・・・・ 3 ・・・・・・－・・・・・・・・・ 4 ・・・・・・・・・・・・・・・・・・ 5・・・・・・・・・・・・・・・ Place・・・・・・・・・ ! R1, R2... CR... VRO... r,... VoN -------- Vopp ...Axis... VTI ...°... V, ......-... DC detection circuit 1st sample hold circuit 2nd sample hold circuit Threshold setting circuit Judgment circuit Telephone Call signal sending relay resistance Call signal source DC power supply DC detection circuit Output 1st sample hold circuit Output 2nd sample hold circuit Output Threshold setting circuit Output judgment circuit Output Diagram 1 Sanskrit 2 Figure 4 Closed Figure 3 Figure 5

Claims (1)

[Claims] 1. In a ring trip circuit that detects a called person's response to a ringing signal and stops the ringing signal, a DC detection circuit that detects a DC signal component superimposed on the ringing signal in order to detect the called person's response; , a first sample and hold circuit that holds the output of the DC detection circuit when the called party is not responding while the calling signal is being sent; and a second sample and hold circuit that holds the output of the DC detection circuit when the called party responds. ,
a threshold setting circuit that sets a threshold for detecting a called party response corresponding to the subscriber line length using the output of the first sample and hold circuit and the output of the second sample and hold circuit; A ring trip circuit comprising: a determination circuit that determines whether a called party response has been detected based on a threshold value for detecting a caller response and an output of the DC detection circuit.