JPS5851465B2 - Response monitoring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a response monitoring system, and more particularly to a response monitoring system for a subscriber's ringing signal in a telephone exchange.

FIG. 1 is a diagram used to explain a conventional response monitoring system.

In FIG. 1, SIG is a calling signal generating device consisting of a calling signal sound source IR1 and a DC power source EO, RGT is an AC silent relay F, a resistor R2, a calling signal sending contact So,
A calling signal sending/response monitoring circuit consisting of S1, L
INE is a subscriber line, and INE is a subscriber telephone.

When the subscriber telephone is placed horizontally, H8o and H81 are the hook switches, Lo is the inductance of the bell circuit, Ro is the DC resistance of the bell circuit, CO is the capacitor of the bell circuit, R1 is the DC resistance of the communication circuit, and the hook switch H8o is Open when on-hook, close when off-hook, hook switch H
81 is closed when on-hook and opened when off-hook.Zlo and Zll are the impedances of the subscriber line LINE.The ringing signal sound source IR is a power source with an average voltage of 75V and an average frequency of 16Hz.

First, a conventional response monitoring system will be explained using FIG.

Since the ringing signal is sent to the horizontal subscriber telephone in the on-hook state, the hook switch H8o is open and the hook switch H8t is closed. At this time, the ringing signal sending contact 80. Sl
When closed, earth-IRF-8o-Zl-Lo R
o Co H81-Zll St R2EO-A 16 Hz ringing current flows through the bell circuit in the earth loop, causing a bell in the subscriber's telephone equipment, not shown, to ring.

The current loop by the DC power supply EO is interrupted by the capacitor Co, and no DC current flows.

Here, the AC insensitive relay F is designed not to be affected by 16Hz alternating current, so it does not operate.When the subscriber picks up the handset or answers, hook switch H8O closes and H81 opens. A DC loop is therefore formed within the subscriber's telephone equipment.

This allows Earth-I RF 5o-Zlo-Rt
-H8o zll sl R2EO In the ground loop, a DC current flows to the AC insensible relay F, and the relay F operates.

A subscriber's response can be detected by monitoring the closing/opening of the contacts of an AC non-sensing relay F (not shown) by a controller of the exchange (not shown).

In other words, the conventional response monitoring system uses an AC non-sensing relay to separate 16 Hz AC current and DC current.

In this way, in the conventional method, it is necessary to separate extremely low-frequency AC signals and DC signals, so the AC and DC separation circuit becomes large and has the drawback that it cannot be made economical. The volume of the impulsive relay is about 170cc.

Next, we will explain the necessity of downsizing and economicalization of response monitoring circuits based on recent trends in switch configuration technology.

With recent advances in integration technology, time-division communication channels using integrated memories and gates are being put into practical use.

Time-division communication paths allow switching of digital codes, but the communication current required to operate existing telephones
Cannot pass high-amplitude signals such as ringing signals.For this reason, in conventional space-division communication paths, the communication current supply circuit was installed at the back of the network and used commonly by many subscribers to save money. It is necessary to provide a paging signal sending circuit, a response monitoring circuit, etc. in front of the network, and these circuits are required to support subscribers. When compared, if the concentration ratio in the space-division communication path is n:1, the number of circuits in the time-division communication path is n times that of the space-division communication path.

The time it takes to ring a subscriber in one call is around 10 seconds, and the usage time of the response monitoring circuit is extremely short, so the number of response monitoring circuits in a conventional space-division communication path is limited to 10,000 subscribers. On the other hand, there are about 30 circuits.

In other words, the concentration ratio of the response monitoring circuit is about 1000:3, and if you ignore other cost factors and focus only on the response monitoring circuit, you can reduce the volume and cost to about 3/1000 of the conventional response monitoring circuit. For the first time, space-division communication paths and time-division communication paths will have the same mounting space and cost.To achieve this, it is no longer possible to achieve this using the conventional method using electromagnetic components. Therefore, digitization and further integration are essential conditions.

Since the number of circuits increases approximately 1000 times, integrated circuits suitable for mass production are a particularly promising miniaturization and economical method. ○The present invention realizes a response monitoring circuit that can be computerized and even integrated. In order to do this, the conventional AC non-sensing relay is removed and will be explained in detail below.

FIG. 2 is a diagram showing the impedance of each part in a calling signal sending state, and the same reference numerals as in FIG. 1 represent the same parts.

zT is the impedance of the telephone at 16Hz in the on-hook state, and is expressed by the symbol in FIG.
) is as follows.

RF is the resistance equivalent to the winding resistance of relay F in Figure 1, VI
R is the output voltage of the ringing signal sound source IR.

In FIG. 2, the loop current Il is determined.

The loop current Il when the phone is on-hook is IIN.

If the loop current ■l in the on-hook state is ■IF, then
IIN and ■IF are expressed by the formula (2X3).

When the telephone is on-hook, the capacitor CO blocks direct current, so the loop current IAN when the telephone is on-hook does not include a direct-current component.

FIG. 3 is a connection diagram of one embodiment of the present invention.

In Figure 3, RF and R2 are the same resistors as in Figure 2, 5WOO, 5WO1, and 5WO2 are contacts, HYB is a 2-wire/4-wire conversion circuit, BNW is a balanced circuit network, BPF is a band pass filter, and LPF is a low pass Filter, C0DE
C is a digital encoding/decoding circuit, 0PAO is a differential amplifier, A and B are terminals for connecting subscriber lines, PCM5 is a digital code output terminal of the digital encoding/decoding circuit C0DEC, and PCMR is its digital code input terminal. be.

5WOO. 5WO1 and 5WO2 are all multi-contact relays S
It is a contact point of WO, and in Fig. 3, 5WOo, SWO
□5WO2 indicates the state when the multi-contact relay SWO is operating.

Next, we will explain its operation.0 First, when the subscriber is in a talking state, the relay SWO is in an inactive state, and the contact s
wo,, 5WOt, swo2 are connected to different contacts from those shown in Fig. 3. When the audio signal v5 reaches the oA and B terminals from the subscriber line, the 2/4-wire conversion circuit HYB converts the bandpass filter BPF. Outputs a signal of v, /2 to the input terminal 0 This is the same as the operation of a known 2-wire/4-wire conversion circuit, so a detailed explanation will be omitted. The filter has a low operating attenuation in the 3400 Hz audio band and a sufficiently large operating attenuation in other bands, and the digital encoding/decoding circuit C0DEC digitally encodes the audio signal and outputs it to the PCM5 terminal.

On the other hand, the digital code input to the PCMR terminal is converted into an analog quantity by the digital encoding/decoding circuit CODEC, and then converted into the original audio signal by the low-pass filter LPF.

This is also the same digital encoding method used in the known PCM24 method and the like.

Next, we will explain the operation while sending out a calling signal.During sending out a 0 calling signal, operate the multi-contact relay SWO and contact 5W.
Oo, 5WO1, and 5WO2 are brought into the state shown in FIG.

The ringing signal current Il is ground-IRRp 5WOo
The signal flows to the subscriber telephone in a loop of A terminal - (subscriber line and subscriber telephone set not shown) - B terminal - 8WOl - R2 - EO - ground, and the bell inside the subscriber telephone rings.

In FIG. 3, the voltage across the resistor RF, that is, the voltage R
F I l is detected by the differential amplifier 0PAO, and the detection output is connected to the digital encoding/decoding circuit C0DEC via the contact SW 02, thereby digitally encoding the value of the voltage RF'Il and outputting it from the PCM5 terminal. do.

At this time, in the conventional method of separating the DC component and 16 Hz AC component and monitoring the response, it is not possible to insert a bandpass filter BPF used for digital audio encoding as shown in Figure 3. , is impossible because the filter BPF blocks direct current.

In FIG. 3, the digital encoding/decoding circuit C0DEC has a function of digitally encoding from a DC component to a voice of 3400 Hz.

The digital code of the voltage RfIl output to the terminal PCM5 is detected separately into a 16 Hz AC component and a DC component by, for example, a digital filter (not shown), and a control device (not shown) detects the DC component as a subscriber response if there is a DC component. judge.

FIG. 4 is a connection diagram of another embodiment of the present invention, and FIG.
Items with the same reference numerals as those in the figures represent the same items.

The difference between FIG. 4 and FIG. 3 is that the DC power source EO in FIG. ○Multi-contact relay SW0.2-wire 4-wire conversion circuit HYB, bandpass filter BPF1 digital encoding/decoding circuit C0DEC, low-pass filter LP at the inserted point
The operation of F is exactly the same as in FIG.

The line current I7 at I in FIG. 4 is the direct current source EO in FIG.
can be considered as a diagram in which VF is replaced with an AC sound source.

(where ZF is the frequency fVF of the AC sound source VF
It is the impedance of the on-hook telephone with respect to the following equation (6).

Next, the frequency fVF will be explained.

In Fig. 4, the output of the differential amplifier 0PAO uses the audio signal bandpass BPF and the digital encoding/decoding circuit C0DEC as they are, so the frequency fVF is selected as a certain frequency within the audio band. ○Therefore, the frequency fVF
The condition is 300Hz≦fVF≦3400Hz.

On the other hand, since the value of Lo in equation (6) is about 80H in existing telephones, the frequency fv within the above conditions
The impedance Zp for F has a sufficiently large value for the resistor R1.

Therefore, response monitoring becomes possible if the telephone set, whose line current Il flows due to the AC sound source VF, detects a difference between the on-hook state and the off-hook state.

An example of realizing this is shown in FIG.
Since the frequency of R is 16Hz, the voltage RFI after passing through the bandpass filter BPF (blocks frequencies below 300Hz)
l can be thought of as (4×5) formula: ■Equation R−O.

Therefore, the loop currents during on-hook and off-hook in this case are respectively detected as IIN' l IIF' below.

0Here, since Z p >> R1, the subscriber's response can be detected by determining the magnitude of the output signal of the PCM5 terminal.

As explained above, according to the present invention, in a time division exchange, if a differential amplifier and contact 5WO2 are newly added to the subscriber circuit for response monitoring, the digital code required for digital encoding of voice signals can be The line current value during the sending of the ringing signal can be digitally encoded using the encoding circuit (or its encoding function in the case of a digital encoding/decoding circuit).

Therefore, the subscriber's response can be detected by a common digital processing circuit having a digital filter after the network, and the response monitoring circuit necessary for responding to the subscriber can be simplified. An economical response monitoring method can be provided.

Furthermore, since the differential amplifiers required for subscriber support can be easily integrated, and the contacts can be integrated as electronic switches, economics can be expected through mass production.

[Brief explanation of the drawing]

Fig. 1 is a diagram used to explain the conventional response monitoring system, Fig. 2 is a diagram showing the impedance of each part in a state where a calling signal is sent, Fig. 3 is a connection diagram of an embodiment of the present invention, and Fig. 4 is a diagram used in the present invention. FIG. 7 is a connection diagram of another embodiment of the invention. SIG... Calling signal generator, RGT...
...Call signal sending/response monitoring circuit, LINE...
...Subscriber line, installation...Subscriber telephone, F...
...AC insensible relay, IR...Call signal sound source, EO...DC power supply, So, St, H
8o, H81, 5WOo, 5W (h. 5WO2...Contact, Ro, Rt t R2+
Rp ``・''・Resistance, Lo...Interface, co...Capacitor, Zl, Zl, Z
T, ZF... impedance, 0PAO...
... Differential amplifier, HYB ... 2-wire/4-wire conversion circuit, BNW ... Balanced circuit network, BPF ...
... Band pass filter, LPF ... Low pass filter, C0DEC ... Digital encoding/decoding circuit, VF ... AC sound source.

Claims (1)

[Scope of Claims] 1. In a paging system in a time-division exchange in which a telephone is called by a paging AC signal sent to a subscriber line, means for monitoring and detecting the line current of the subscriber line while the paging signal is being sent and outputting it. , a switch for inputting the detection output of the above means into a circuit that digitally encodes a voice signal from the telephone; and means for monitoring and determining the detection output digitally encoded by the digital encoder circuit while the calling signal is being sent. A response monitoring system, characterized in that the monitoring and determining means monitors a subscriber's response. 2. Claim No. 2, characterized in that the output of a means for superimposing a direct current on a calling alternating current signal and sending it out, monitoring and detecting a line current, and outputting it is input to a circuit that digitally encodes everything from the direct current component to voice. Response monitoring method described in Section 1. 3. An AC signal within the audio band is superimposed on the AC signal for calling, and the output of the means for monitoring and detecting the line current is sent through a band pass filter used for digitally encoding the audio signal from the telephone. 2. The response monitoring system according to claim 1, wherein the response monitoring system is input to a circuit for digital encoding.