JPS5919675B2 - Subscriber circuit signal processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a signal processing device in a telephone subscriber circuit.

In recent years, with the development of all-electronic exchanges, it has become necessary for subscriber circuits to be equipped with numerous functions.

For example, it is equipped with a DC monitoring function for calling/terminating a call and detecting dial pulses, and a function to stop sending calls, signals, and responses thereto. In general, in conventional subscriber circuits, in order to perform the operations described above, a detector is used to sense the on/off state of the DC loop current that occurs when a subscriber makes and ends a call, and when dialing pulses are sent out, and a When transmitting signals, it was equipped with a detector that was not sensitive to the ringing signal, but was sensitive to the DC loop current generated by the subscriber's response.

However, since the subscriber circuit of a telephone exchange is installed for each subscriber, the cost of the subscriber circuit directly affects the cost per terminal of the exchange.

Therefore, in order to reduce costs, it is necessary to construct a subscriber circuit with as few components as possible. One object of the present invention is to provide a signal processing device for a subscriber circuit that can perform subscriber circuit loop monitoring, ring trip signal detection, etc. using a common signal processing system.Other objects of the present invention The object of the present invention is to provide a signal processing device for subscriber circuits that commonly performs signal processing systems for a plurality of subscriber circuits.

Yet another object of the present invention is to provide an economical subscriber circuit signal processing arrangement.

In order to achieve the above object, the present invention provides means for detecting signals flowing in a subscriber circuit, analog multiplexing means for multiplexing the outputs of these detection means, and converting the output from the analog multiplexing means into a digital signal. and a signal processing means for processing the output from the analog-to-digital converting means.

Now, before explaining the present invention, a subscriber circuit previously filed by the present applicant will be explained with reference to FIG.

This subscriber circuit is described in detail in Japanese Patent Application No. 53-4356 ``Direct Current Magnetic Field Cancellation Circuit''. In the figure, 1 is a subscriber's telephone, 2 is an AC power supply with a frequency of 16 Hz and a voltage of 75 Vrms, that is, a calling signal source, and 3 is a relay contact that switches between sending and stopping the calling signal. 4 is a subscriber transformer, which has a secondary winding 4b connected from the primary windings 4a and 4a to the relay line.
The audio signal is transmitted to.

4c is a winding for canceling the DC magnetic field generated in the subscriber transformer 4; 5 is a magnetoelectric conversion element 6 such as a Hall effect element magnetically coupled to the subscriber transformer 4; a capacitor having the function of a low-pass filter for attenuating the audio signal is added thereto; 7 is a voltage/current conversion means, 8 is a DC signal detection circuit such as a loop monitoring circuit and a dial pulse detector, 9 is a low-pass filter for attenuating a ringing signal, and 10 is a ring trigger signal detection circuit.

In the above circuit configuration, the magnetic flux generated by the subscriber transformer 4 is detected by the magnetoelectric conversion element 5, passed through the voltage amplifier 6, converted to current by the voltage/current conversion means 7, and then converted to a current by the DC magnetic field canceling winding 4c. Negative feedback is provided to the subscriber transformer 4.

This negative feedback eliminates the magnetic saturation of the iron core of the subscriber transformer 4 and improves the transmission characteristics for audio signals. At the same time, the changes in the DC signal when the subscriber telephone 1 makes and ends a call, sends out a dial pulse, and responds when sending out a ringing signal are determined by the magnetoelectric conversion element 5, the voltage amplifier 6,
, are detected by the DC signal detection circuit 8 and the ring trip signal detection circuit 10, respectively, via the voltage/current conversion means 7. These output signals are each introduced into the main processor by a scanning device (not shown). Generally, a plurality of such subscriber circuits are provided, and each subscriber circuit requires the above-mentioned DC signal detection circuit and ring top signal detection circuit, resulting in high cost. The present invention solves the above-mentioned drawbacks by making the signal processing portion of the subscriber circuit common.

Hereinafter, it will be explained in detail using the drawings. FIG. 2 is a circuit diagram showing one embodiment of the present invention.

In the figure, reference numeral 7 denotes a voltage/current conversion means, which is a part of the subscriber circuit, but the other parts are the same as those in FIG. 1 and are therefore omitted here. 1
1 is an analog multiplexer to which signal terminals Al, a2, . . . An from a plurality of subscriber circuits are connected.

12 is an analog-to-digital converter (hereinafter referred to as an A-D converter).

), 13 is a signal processing circuit, and 14 is a conventionally known main processor for controlling the exchange. The death in the same figure is the first
Terminal a of the voltage/current conversion means 7 of the subscriber circuit in the figure
1 (note that other subscriber circuits are omitted). Analog multiplexer 11
is the signal station. From the logic circuit 13 (details will be described later) to the signal line 1
Analog signals from a plurality of subscriber circuits are periodically switched by a selection signal sent through 5 and sent to an A/D converter 12. The A-D converter 12 converts the analog signal into, for example, an 8-bit digital signal and sends it to the signal processing circuit 1.
Send to 3. The signal processing circuit 13 processes periodically input digital signals and identifies the status of each subscriber. The analog signals sent from the subscriber circuit include changes in the DC signal that occurs when the subscriber's telephone makes and ends a call, and when a diamond pulse is sent out, and a DC signal that is superimposed on the ringing signal that appears when responding to the sending of a ringing signal. There are changes, etc. The signal processing circuit 13 detects these changes, as will be described later, to identify call origination and termination, count diamond pulses, and identify responses to the sending of a calling signal. The above-mentioned operation will be explained in more detail with reference to FIG. 3 showing a specific embodiment of the signal processing circuit 13. In figure 3, terminal 1
20 is connected to a terminal 121 to which the output of the A-D converter 12 is applied.
is connected to analog multiplexer 11, and terminal 1
22 is connected to the main processor 14.

131 and 132 are threshold comparison circuits, hexagrams, and calling/calling circuits, respectively.
The call end identification circuit uses these to detect the loop monitoring circuit 123.
is configured.

133 and 134 are a threshold comparison circuit and a dial pulse discrimination circuit, respectively, which allow the dial counting circuit 1
24 are configured.

135 and 136 are a digital filter and a threshold comparison circuit, respectively, and these constitute the response monitoring circuit 125.

137 is a selection signal generation circuit that drives the analog multiplexer, 138 is a control circuit, and 139 is a memory.

Now, detection of call origination and call termination by a subscriber will be explained. For example, when a subscriber makes a call, the subscriber's telephone changes from an on-hook state to an off-hook state, and a DC signal begins to flow through the subscriber line. The change in the DC signal is detected by the magnetoelectric conversion element 5, appears at the output terminal of the voltage/current conversion means 7 via the voltage amplifier 6, and the signal is applied to the terminal a1. For example, if the subscriber circuit is composed of 256 pieces, the signal due to this state change is sent to the signal processing circuit 13.
It is detected by the loop monitoring circuit 123 which is activated every 128 mS. That is, the selection signal generation circuit 137
A selection signal with a cycle of 128 mS is supplied to the analog multiplexer 11 in FIG. The data is taken into the D converter 12. Note that the analog multiplexer 11 has terminals Al, a2,...
・An. The signals applied to the two are sequentially scanned and analog multiplexed. This signal is converted into an 8-bit digital signal by the A/D converter 12 and input to the threshold comparison circuit 131. The input digital signal is compared with a digital threshold value for determining the presence or absence of a DC signal in the subscriber circuit. When the comparison result is 3'0'5, the subscriber is on-hook, and when it is '1', the subscriber is off-hook.The '1' and 'O' outputs of this threshold comparison circuit 131 are It is input to the call identification circuit 132. When the call origination/end call identification circuit 132 receives this input and the previous scanning time stored in the memo 1 river 39, that is, 128m
It is detected whether the subscriber is a new calling subscriber or a terminated subscriber based on the input at the time of scanning before S. In other words, if the current input is "1", the memory 139
When the input from the subscriber is "0", the subscriber is deemed to be a new calling subscriber and the subscriber number is stored in the memory 139.
Similarly, when detecting the end of a subscriber's call, the output of the threshold comparison circuit 131 is "o" and the input from the memory 139 is "1".
'', the end of the subscriber's call is detected. However, if you only compare the current state with the state at the time of scanning 128 mS ago, it is likely that this operation will occur due to chattering, etc., which will directly reduce the reliability of the call. Therefore, in an actual exchange,
The signals of the previous time and the time before the previous time are read out from the memory 139, and when the outputs of the time before the previous time and the time before the previous time are respectively "1-"0", it is assumed that the subscriber in question has terminated the call, and the subscriber number is stored in the memory 139. In this way, every 128 mS, analog signals from 256 subscriber lines S, which are not in a calling state from another station or another subscriber, are sequentially selected by the analog multiplexer 11 and sent to the loop monitoring circuit. 123.

All newly detected calling subscribers and ending subscribers are stored in memory 139. Information about the subscriber line in the ringing state, for example the subscriber number, has previously been stored in the memory 139 via the main processor 14 (these techniques are well known in the art, so details thereof will not be given). (omitted)), the signal from the memory 139 is sent to the selection signal generation circuit 1 under the control of the control circuit 138.
37 and corresponds to the subscriber line in question.
The configuration is such that the selection signal for each is not output. Therefore, a signal from a subscriber in a ringing state is not captured by the A/D converter 12 with this selection signal. Following the above description, a method for detecting the dial count of a new calling subscriber when that subscriber is detected will now be described.

As previously explained, the new calling subscriber number is stored in the memory 139, and its contents are sent to the main processor 14 for use in various controls. In this case, the telephone number of the subscriber that the new subscriber wishes to call, that is, the number of dialed numbers and the number of digits, is detected. Here, a control signal for dial counting is sent from main processor 14 to control circuit 138. The control circuit 138 operates the dial counting circuit 124, for example, every 8 mS, and sequentially reads data from the memory 139.
Information regarding the new dial subscriber number is sent to the selection signal generation circuit 137. The selection signal generation circuit 137 sends a selection signal to the analog multiplexer 11 via the signal line 17 at a cycle of, for example, 8 mS in order to receive a dial signal from the subscriber line corresponding to the subscriber number. The captured dial signal is converted into a digital signal by the AD converter 12 shown in FIG. 2, and is applied to the dial counting circuit 124. In the dial counting circuit 124, first, the input digital signal is compared with a digital threshold value in a threshold comparison circuit 133 to determine the presence or absence of a DC signal that affects the subscriber circuit. Detection is performed. The "1" and "O" signals as a result of this comparison are inputted to the dial pulse identification circuit 134 and stored in the memo 39. Dial pulse identification circuit 1
Reference numeral 34 is a conventionally known circuit, but to briefly explain, dial pulses are counted based on the comparison result of the comparison circuit 133 and the comparison result of scanning 8 mS before.
That is, when the current comparison result is "O" and the comparison result 8 mS ago is "1", the first counter in the dial number identification circuit 134 counts as a tire number L//'0 response. On the other hand, when the comparison result is 801, the second counter in the dial pulse identification circuit 134 is set to, for example, a digital value of 13. This is used, for example, to distinguish between numbers on a dial. The contents of this second counter are always subtracted by l when the comparison result is "1"" and the contents of the second and second counters are not "O"". Now, when the comparison result is ``12'' and the content of the first counter is not ``O'''' and the content of the second counter is ``O'5,'' the number of dial digits is incremented by one, and the first counter is Transfer the count value of the dial pulse of the counter to a temporary storage register. These operations are executed sequentially and the dialed numbers and number of dialed digits are stored in the memory 139. This stored content is sent to the main processor 14, as is well known in the art, and is used to control the exchange. Next, a method for detecting a response from a subscriber to whom a calling signal is sent from the other subscriber described above will be explained.

The number of the subscriber to be called by another subscriber is stored in the main processor 14 in a conventional manner. Accordingly, information about the currently calling subscriber, such as the subscriber number, is sent to the memory 139 and stored therein. On the other hand, under the control of the main processor 14, the response monitoring circuit 125 is operated every 8 mS by a control signal from the control circuit 138. At the same time, the subscriber number in the calling state stored in the memory 139 is read out and sent to the selection signal generation circuit 137. The selection signal generation circuit 137 sends a selection signal with a cycle of 8 mS to the analog multiplexer 11 in order to input the analog signal from the corresponding subscriber circuit into the A-D converter 12. Note that this selection signal is generated at a different timing from the selection signal for dial counting described above. This selection signal with a period of 8 mS is applied to the analog multiplexer 11, which analog-multiplexes the signals from all the subscribers in the calling state, and sequentially sends the signals to the A-D converter 1.
Send to 2. The A/D converter 12 converts this signal into an 8-bit digital signal and sends it to the response monitoring circuit 125. The response monitoring circuit 125 includes, for example, a digital filter 135 for removing a 16 Hz calling signal and a threshold comparison circuit 136.

Since the configuration of the digital filter 135 is conventionally known, its explanation will be omitted, but its input/output voltage is expressed by the following equation. Now, input voltage f(t) and output voltage h
(t), where C and R respectively represent the capacitance and resistance of the primary CR filter.

The output h(t) of this digital filter 135 is applied to a threshold comparison circuit 136 and compared with a digital threshold,
The presence or absence of a response from the subscriber is detected.

To explain more specifically, if the sampling period γ in equation (1) is 8 mS and the CR time constant is 120 mS, then the following equation is obtained.

On the other hand, as the digital threshold of the threshold comparison circuit 136, the current flowing through the subscriber line is about 10rr1A, and the terminal a1
The voltage at is set to a value corresponding to 0.5V. For example, a digital threshold value of 256 is set. In fact, if the A-D conversion is set in the A-D converter 12 so that the analog signal 0.5V corresponds to the digital signal 16, processing of the coefficient B in the digital filter 135 becomes unnecessary, and the digital filter calculation Comparison of the processing results with threshold values can be performed when the digital filter 135 outputs an 8-bit overflow. In this way, off-hook and on-hook states are identified, and presence or absence of a response from the subscriber to the sending of a ringing signal is detected.

When an off-hook condition is detected, ie, a subscriber has responded, the subscriber number is stored in memory 139.
As mentioned above, the new calling subscriber number, ending subscriber number, dialed subscriber number, number of dials, number of dialed digits, response subscriber number, etc. stored in the memorandum 39 are stored in the control circuit. The control signal from signal line 138
The data is sent to the main processor 15 as appropriate through the switch, and the subsequent processing by the exchange is the same as in the prior art, so a description thereof will be omitted here.

In the above explanation, it has been explained that the detection of call origination, call termination, dial counting, etc. is performed by the signal processing circuit shown in FIG. 3, but these operations can also be performed by a microcomputer. Needless to say.

FIG. 4 shows a specific example of the configuration of the analog multiplexer 11 shown in FIG.

In the same figure, 111-1 to 111-m, and 112
are analog multiplexers each having, for example, 16 inputs. For example, each of the 256 subscriber circuits has 16 analog signals (k=16 in the figure).
The signal is input to 16 (m=16 in the figure) analog multiplexers 111-1 . . . 111-m having input terminals. The outputs of the 16 analog multiplexers are input to analog multiplexer 112.

When the selection signal sent via the signal line 15 is an 8-bit signal, the upper 4 bits are sent to the analog multiplexer 112.
The lower 4 bits are used by the analog multiplexer 11.
1-1...111-m. Lube monitoring performed every 128 mS for each subscriber can be performed as follows using the configuration shown in FIG. That is, each group of subscriber lines divided into 16 groups is selected one by one every 8 mS by analog multiplexers 111-1...111-M, ll2.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of a conventional subscriber circuit, FIG. 2 is a diagram showing an embodiment of the signal processing device of the present invention, and FIG.
FIG. 4 is a diagram showing an embodiment of the main part of the figure, and FIG. 4 is a diagram showing an embodiment for analog multiplexing.

Claims (1)

[Scope of Claims] 1. An analog signal extraction circuit that is provided for each of a plurality of subscriber circuits and outputs an analog signal that changes depending on the direct current flowing through each subscriber circuit and the calling alternating current signal; an analog multiplexing circuit commonly connected to the output terminal;
an analog-digital converter connected to an output end of the analog multiplexing circuit, and a signal processing circuit connected to an output end of the analog-digital converter, the signal processing circuit connecting the multiplexing circuit a control means for supplying a selection signal for selectively taking in the output analog signals from the plurality of extraction circuits; and a control means connected to the analog-to-digital converter for controlling the digital signals output from the converter to a predetermined digital threshold. and a means for identifying a change in the state of the subscriber circuit from the output of the threshold comparison means. Signal processing equipment for subscriber circuits. 2. The signal processing circuit has a memory for storing state information for each subscriber circuit, and the identification means is configured to use the output from the threshold comparison means and the previous status information of the subscriber circuit stored in the memory. 2. The signal processing device for a subscriber circuit according to claim 1, wherein the state information in the memory is updated in accordance with the relationship with the state information of the subscriber circuit. 3. The signal processing circuit includes dial pulse counting means connected to the analog-to-digital converter, and the dial pulse counting means:
From the output of the analog-to-digital converter and the previous state information of the subscriber circuit stored in the memory,
Claim 2, characterized in that the dial pulses are counted and the number of digits of the dial number is written in the memory.
A signal processing device for a subscriber circuit as described in 2.