Ringing signal amplitude limiting detection device

Abstract

A ringing signal amplitude limiting detection device comprises a ringing generator, a ringing signal adjustment driving part and a voltage detection and amplitude limiting judgment part. And the ringing signal adjusting driving part is used for receiving the gain adjusting signal and the ringing signal generated by the ringing generator, adjusting the gain of the ringing signal according to the gain adjusting signal and then outputting the ringing signal to the user loop. And the voltage detection and amplitude limiting judgment part is coupled with the user loop and detects the loop voltage waveform so as to judge whether the amplitude of the ringing signal is limited or not according to whether the detected voltage waveform is discontinuous or not. When the amplitude limit of the ringing signal is judged, the voltage detection and amplitude limit judgment part drives the ringing signal adjustment driving part through the gain adjustment signal to attenuate the ringing signal.

Description

Technical Field

[0001] The present invention relates to a detection device, and in particular to a ringing signal amplitude limiting detection device for detecting whether a ringing signal is amplitude limited and adjusting its gain accordingly. Background Art

[0002] In telephone communication systems, signals are transmitted between a subscriber station and a central switching office via twisted pair cables. These signals include "Tip" and "Ring" signals. The twisted pair cables between the subscriber station and the central switching office can be connected via a Subscriber Line Interface Circuit (SLIC). The function that this SLIC can provide is usually called "BORSCHT".

[0003] The following is a brief description of the functions of "BORSCHT".

[0004] [B]:Battery Feeding

[0005] SLIC can provide a DC voltage level between the tip and ring for communication, as well as the current required for signaling. The amplitude (absolute value) of this DC voltage is usually 48V.

[0006] [O]: Over Voltage Protection

[0007] Telephone lines may be subject to dangerous voltages from lightning strikes, downed power lines, etc. Therefore, arresters such as gas tubes or carbon blocks are installed in the central office. However, line cards must be able to withstand 1000V surges.

[0008] [R]:Ringing

[0009] The SLIC is usually responsible for generating a ringing signal, which has a root mean square value of 86V, a frequency of 20Hz, and a periodicity of 2 seconds ON and 4 seconds OFF.

[0010] [S]:Signaling

[0011] Also commonly referred to as "Supervision", SLIC monitors the status of the (user) line, mainly by monitoring the current of the user loop (also called the user return) to determine whether the phone is on-hook or off-hook. In addition, it also includes the decoding of Dual-Tone Multi-Frequency (DTMF) dialing numbers, flash hooks, and other signal monitoring.

[0012] [C]:Coding

[0013] The coding includes μ-Law coding in North America and A-Law coding in Europe. It also includes analog-to-digital conversion, digital-to-analog conversion, and time-division multiplexing companding and framing.

[0014] [H]:Hybrid

[0015] This function realizes the circuit conversion from two-wire to four-wire.

[0016] [T]:Testing

[0017] This function provides test paths for battery voltage, loop current, ringing voltage, Tip-Ring resistance, Tip-ground resistance, and Ring-ground resistance.

[0018] As mentioned above, the RMS value of the (Tip / Ring) voltage of the ringing signal is usually 86V (peak to peak value is about 120V). This means that the SLIC must provide a voltage higher than 120V to maintain the integrity of the ringing signal. When the Ringer Equivalent Number (REN) increases, it means that the load of the entire user line increases, and more power supply is required to maintain the desired ringing voltage. However, if the feed cannot provide enough power, the ringing signal will be clipped, that is, the waveform of the signal is cut or distorted.

[0019] Figure 1A A waveform diagram showing the ringing signal (including Tip / Ring signal) when REN=1; Figure 1B The waveform diagram of the ringing signal when REN = 3 is shown. Figure 1A In this case (REN = 1), the feed can provide enough power to keep the ringing signal in its waveform. Figure 1BIn this case, when the user line load increases to REN=3, the feeder cannot provide sufficient power, so the Tip / Ring signal will not be able to reach the peak value, but will be clipped and distorted.

[0020] Users do not want to hear distorted ringing signals, so they usually try to ensure the integrity of the ringing signal waveform by increasing the power supply or reducing the gain of the ringing signal. However, whether increasing the power supply or reducing the gain of the ringing signal is used, the first task is to detect whether the ringing signal is clipped. Only by successfully detecting and confirming that the ringing signal is clipped can we improve it by increasing the power supply or reducing the gain of the ringing signal. Summary of the invention

[0021] In view of this, the present invention provides a ringing signal amplitude limiting detection device, which detects the ringing signal amplitude limiting independently of the amplitude and frequency of the ringing signal to remove the influence of the amplitude and frequency of the ringing signal, and the threshold value does not need to change with the amplitude of the ringing signal.

[0022] The present invention provides a ringing signal clipping detection device, comprising: a ringing generator, a ringing signal adjustment driving unit, and a voltage detection and clipping judgment unit. The ringing generator generates a ringing signal according to a ringing parameter. The ringing signal adjustment driving unit receives the ringing signal and a gain adjustment signal, attenuates the gain of the ringing signal according to the gain adjustment signal, or maintains the gain of the ringing signal, and then outputs the ringing signal to the user loop. The voltage detection and clipping judgment unit is coupled to the user loop and detects the voltage waveform of the ringing signal, thereby judging whether the above-mentioned ringing signal is clipped according to whether the voltage waveform of the detected ringing signal is discontinuous. Wherein, when it is judged that the above-mentioned ringing signal is clipped, the above-mentioned voltage detection and clipping judgment unit drives the above-mentioned ringing signal adjustment driving unit to attenuate the above-mentioned ringing signal through the above-mentioned gain adjustment signal.

[0023] In some embodiments, the voltage detection and limit determination unit further comprises: a voltage detection unit and a limit determination unit. The voltage detection unit detects the voltage waveform of the ringing signal. The limit determination unit is configured to perform the following actions: (1) for each detection point of the voltage waveform, calculate the left limit and the right limit of the detection point; (2) determine whether the difference between the left limit and the right limit is greater than or equal to a set threshold value; (3) when the difference between the left limit and the right limit is greater than or equal to the set threshold value, determine that the voltage waveform is discontinuous; and (4) in response to the determination that the voltage waveform is discontinuous, send the gain adjustment signal to drive the ringing signal adjustment drive unit to attenuate the ringing signal.

[0024] In some embodiments, the voltage detection and amplitude limiting determination unit further includes a low-pass filter coupled between the voltage detection unit and the amplitude limiting determination unit to perform low-pass filtering on the voltage waveform before outputting it to the amplitude limiting determination unit.

[0025] In some embodiments, the limit determination unit further includes a limit calculator and a comparator. The limit calculator receives the voltage waveform to calculate the left limit and the right limit of the detection point. The comparator compares the difference between the left limit and the right limit with a set threshold value; and when the difference is greater than or equal to the set threshold value, a gain adjustment signal is sent to drive the ringing signal adjustment driving unit to attenuate the ringing signal.

[0026] In some embodiments, when the difference is less than the set threshold value, the comparator drives the ringing signal adjustment driving unit to keep the gain of the ringing signal at 0 dB through the gain adjustment signal.

[0027] In some embodiments, the voltage waveform of the ringing signal is a tip voltage waveform or a ring voltage waveform.

[0028] In some embodiments, the Ring voltage waveform is a sine (cosine) waveform, and the Tip voltage waveform is a cosine (sine) waveform.

[0029] In some embodiments, the threshold is set to a fixed value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A A schematic diagram showing the waveform of a ringing signal (including a Tip / Ring signal) when REN=1 in the prior art.

[0031] Figure 1B A schematic diagram showing the waveform of a ringing signal when REN=3 in the prior art.

[0032] Figure 2 The schematic diagram shows the structure of a ringing signal amplitude limiting detection device 200 without a reference voltage according to an embodiment of the present invention.

[0033] Figure 3 The schematic diagram shows the structure of a ringing signal clipping detection device 300 with a reference voltage according to an embodiment of the present invention.

[0034] Figure 4 A schematic diagram showing the structure of a ringing signal amplitude limiting detection device 400 of the present invention.

[0035] Figure 5 A waveform diagram of a ringing signal when amplitude limiting occurs in an embodiment of the present invention is shown.

[0036] Figure 6 and Figure 7The simulation results of the clipping detection in the embodiment of the present invention are shown.

[0037] Description of Figure Numbers:

[0038] 200,300,400: Ringing signal limit detection device

[0039] 201,301,401: Ringing generator

[0040] 202,302,402a: Ringing gain adjuster

[0041] 203,303,402b: Ringing driver

[0042] 204,304: Loop voltage detector

[0043] 205,305: Loop voltage comparator

[0044] 206,306: Loop

[0045] 300: Ringing signal limit detection device

[0046] 307: Ringing parameters

[0047] 402: Ringing signal adjustment drive unit

[0048] 403: Voltage detection and limit determination unit

[0049] 403a: voltage detection unit

[0050] 403b: Limiting judgment unit

[0051] 403b1: Limit Calculator

[0052] 403b2: Comparator

[0053] 403c: Low pass filter

[0054] 406: User loop

[0055] 601,701: Ringing signal waveform

[0056] 602,702: Difference between right limit and left limit

[0057] COMP_THD: Threshold value

[0058] RS: Ringing signal

[0059] RGA: Gain adjustment signal DETAILED DESCRIPTION

[0060] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings.

[0061] One of the functions of SLIC (Subscriber Line Interface Circuit) is to generate a ringing signal. SLIC can control the amplitude, frequency, and on / off duty of the ringing signal. In addition, a feedback path is provided to SLIC to monitor the status of the subscriber line, such as the peak loop voltage |VTIP-VRING|, where VTIP is the voltage of the Tip signal on the subscriber line and VRING is the voltage of the Ring signal on the subscriber line.

[0062] Depend on Figure 1A and Figure 1B It can be seen that when the ringing equivalent number changes from REN=1 to REN=3, the absolute value of the peak loop voltage |VTIP-VRING| will decrease, and the ringing signal will be limited on the user line. This feature can be used to detect the occurrence of limiting. When the peak value of the peak loop voltage of the monitored user line is less than the preset threshold value, it can be considered that limiting has occurred.

[0063] In this detection architecture, the peak value of the monitored loop voltage is compared with an absolute preset threshold value without a common reference value. This architecture is called a "no reference voltage detector".

[0064] Figure 2 The schematic diagram of the structure of the ringing signal amplitude limiting detection device without reference voltage in an embodiment of the present invention is shown. The ringing signal amplitude limiting detection device 200 includes a ringing generator 201, a ringing gain adjuster 202, a ringing driver 203, a loop voltage detector 204, and a loop voltage comparator 205. The ringing generator 201 generates a corresponding ringing signal (including a Tip signal / Ring signal) according to the (programmed) set parameters of the ringing signal, such as amplitude, frequency, and duty ratio. The ringing gain adjuster 202 receives the ringing signal, attenuates the above ringing signal with a predetermined gain when amplitude limiting occurs, and maintains the gain at 0dB when amplitude limiting does not occur. The ringing driver 203 receives the gain adjustment output by the ringing gain adjuster 202, and outputs a ringing signal to drive the loop (subscriber line) 206. The loop voltage detector 204 monitors the voltage of the Tip signal and the voltage of the Ring signal on the loop 206, and calculates |VTIP-VRING| to detect the occurrence of clipping and find the peak value. The loop voltage comparator 205 compares the peak voltage of the loop 206 with the preset threshold COMP_THD. If the peak loop voltage is less than the threshold COMP_THD, the loop voltage comparator 205 will send an adjustment signal to the ringing gain adjuster 202 to attenuate the ringing signal.

[0065] Although, Figure 2 The detection device 200 has a simple structure and high cost-effectiveness, but a major disadvantage is that the preset threshold COMP_THD must change with the amplitude of the ringing signal.

[0066] When the ringing signal amplitude is large, the threshold value must be set larger, otherwise, the clipping event may never occur; but when the ringing amplitude becomes smaller, the threshold value must be reduced accordingly, otherwise, the clipping event may always occur. In this way, the user must prepare all the required mapping relationship data between the ringing amplitude and the clipping threshold value, which will complicate the programming process.

[0067] In order to improve the aforementioned detection device 200 , a “detector with reference voltage” is proposed. Figure 3 The schematic diagram of the structure of the ringing signal clipping detection device 300 with reference voltage in the embodiment of the present invention is shown. The ringing signal clipping detection device 300 includes a ringing generator 301, a ringing gain adjuster 302, a ringing driver 303, a loop voltage detector 304, and a loop voltage comparator 305. The operation of the ringing generator 301, the ringing gain adjuster 302, the ringing driver 303, and the loop voltage detector 304 is similar to that of the ringing generator 301. Figure 2 The descriptions are the same and their descriptions are omitted here for the sake of brevity.

[0068] The ringing parameter 307 is provided to the ringing generator 301 and the loop voltage comparator 305. The loop voltage comparator 305 receives the ringing parameter 307 and performs the operation of the following equation (1).

[0069] DIFF = RING_AMP-(VLOOP_PEAK) / 2 (1)

[0070] Here, RING_AMP represents the amplitude of the set ringing signal, and VLOOP_PEAK represents the peak value of the loop voltage obtained by monitoring the loop 306 .

[0071] There is a fixed relationship between the peak value (VLOOP_PEAK) of the loop voltage obtained by monitoring the loop 306 and the amplitude (RING_AMP) of the ringing signal set above, which is ideally shown in the following equation (2).

[0072] VLOOP_PEAK = 2×RING_AMP (2)

[0073] If clipping does not occur, the peak value of the loop voltage VLOOP_PEAK will be quite close to twice the amplitude of the ringing signal RING_AMP.

[0074] Applying equation (2) to equation (1), the ringing clipping detection criterion is shown in equation (3).

[0075]

[0076] COMP_THD is a threshold value for detecting clipping. When RING_CLIP=1, it indicates that clipping does not occur. When RING_CLIP=0, clipping occurs.

[0077] Figure 3 The detection device 300 can eliminate the dependence on the amplitude of the ringing signal, so a single threshold value COMP_THD can be applied to any amplitude. However, due to frequency selectivity, different frequency tones will be affected by different channel gains. Frequency selectivity causes ringing signals (RING_AMP voltage) with different frequencies but the same amplitude to have different loop voltage peaks VLOOP_PEAK on the loop 306 due to the influence of frequency. As a result, the relationship between the above equation (2) for signals of different frequencies will not always hold. The effect of frequency selectivity may not be significant, but in the worst case, a programming table for various frequency tones may still be required.

[0078] Figure 4 The schematic diagram of the structure of the ringing signal amplitude limiting detection device 400 of the present invention is shown. Figure 4 The ringing signal amplitude limiting detection device 400 includes a ringing generator 401, a ringing signal adjustment driving unit 402, and a voltage detection and amplitude limiting determination unit 403.

[0079] The ringing generator 401 generates a corresponding ringing signal RS (including Tip / Ring signal) according to the parameters of the ringing signal that have been (programmed), such as amplitude, frequency, duty cycle, etc., and outputs it to the ringing signal adjustment driving unit 402. The voltage waveform of the ringing signal RS includes the voltage waveforms of the Tip (tip) signal and the Ring (round) signal.

[0080] The ringing signal adjustment driving unit 402 receives the ringing signal RS and a gain adjustment signal RGA, and attenuates the gain of the ringing signal RS or maintains the gain of the ringing signal RS according to the gain adjustment signal RGA, and then outputs the ringing signal RS to the user loop 406.

[0081] The voltage detection and clipping determination unit 403 is coupled to the user loop 406 and the ringing signal adjustment driving unit 402, and monitors the voltage waveform of the Tip signal or the Ring signal on the user loop 406, and further determines whether the voltage waveform is discontinuous, so as to determine whether the ringing signal RS, or the Tip signal or the Ring signal of the user loop 406 is clipped. When it is determined that the ringing signal RS (or the Tip signal or the Ring signal of the user loop 406) is clipped, the clipping detection and determination unit 403 drives the ringing signal adjustment driving unit 402 to attenuate the ringing signal RS through the gain adjustment signal RGA. When the Tip signal or the Ring signal of the user loop 406 is clipped, the ringing signal RS is also correspondingly clipped. For the sake of brevity, the "determining whether the ringing signal RS, or the Tip signal or the Ring signal of the user loop 406 is clipped" is collectively referred to as "determining the ringing signal RS".

[0082] The voltage detection and amplitude limiting judgment unit 403 further comprises: a voltage detection unit 403a and an amplitude limiting judgment unit 403b. The voltage detection unit 403a detects and obtains the voltage waveform of the ringing signal RS from the user loop 406, that is, the voltage waveform of the Tip or Ring signal of the user loop 406; the voltage waveform of the Ring signal is used as an example below.

[0083] The limit determination unit 403b is configured to: (1) calculate the left limit and the right limit of each detection point of the voltage waveform of the Ring signal; (2) determine whether the difference between the left limit and the right limit is greater than a set threshold value COMP_THD; (3) when the difference between the left limit and the right limit is greater than (greater than or equal to) the set threshold value COMP_THD, determine that the voltage waveform of the Ring signal is discontinuous; and (4) when it is determined to be discontinuous, send a gain adjustment signal GRA to drive the ringing signal adjustment drive unit 402 to attenuate the ringing signal RS.

[0084] The limit determination unit 403b further includes a limit calculator 403b1 and a comparator 403b2. The limit calculator 403b1 receives the voltage waveform of the Ring signal and calculates the left limit and the right limit of each detection point; the comparator 403b2 compares the difference between the left limit and the right limit with the set threshold COMP_THD. When the difference is greater than or equal to the set threshold COMP_THD, a gain adjustment signal RGA is sent to drive the ringing signal adjustment drive unit 402 to attenuate the ringing signal RS. In addition, when the difference is less than the set threshold COMP_THD, the comparator 403b2 drives the ringing signal adjustment drive unit to maintain the gain of the ringing signal through the gain adjustment signal RGA, that is, to maintain the gain at 0dB.

[0085] In addition, the ringing signal adjustment and driving unit 402 further includes a ringing gain adjuster 402a and a ringing driver 402b. When clipping occurs, for example, when receiving an indication of a gain adjustment signal RGA from the clipping judgment unit 403b, the ringing gain adjuster 402a attenuates the above ringing signal with a predetermined gain, and when clipping does not occur, the gain is kept at 0dB. The ringing driver 402b receives the gain adjustment output by the ringing gain adjuster 402a to output the ringing signal RS to the user loop 406.

[0086] The voltage detection and amplitude limiting determination unit 403 further includes a low pass filter (LPF) 403c coupled between the voltage detection unit 403a and the amplitude limiting determination unit 403b to perform low pass filtering on the voltage waveform to filter out high frequency noise before outputting it to the amplitude limiting determination unit 403b.

[0087] Figure 5 The waveform of the ringing signal when the amplitude is limited is shown. Here, the waveform of the ringing signal is taken as an example. Figure 5 The waveform of the Ring signal with limited amplitude can be divided into three areas A to C as follows:

[0088] (i) Region A is a normal ringing region. In this region, the waveform of the Ring signal is, for example, a continuous sine wave (the waveform of the Tip signal not shown is a continuous cosine wave), and from a mathematical point of view, each point in this region is differentiable.

[0089] (ii) Region B is the clipping region. In this region, the clipped waveform can be continuous or discontinuous, and each point in this region can be differentiable or non-differentiable.

[0090] (iii) Turning point TP, where one side of the point is a continuous sine wave and the other side is a limited waveform. Obviously, this turning point is discontinuous and non-differentiable.

[0091] Figure 5 In the embodiment of the present invention, only the voltage waveform of the ringing signal (Ring signal) in region A is not clipped, so each point of the waveform (in region A) is differentiable. On the other hand, if the Ring signal waveform is clipped, there will be a point in the waveform that is not differentiable. Since the differentiability of the ringing signal waveform is independent of the amplitude and frequency of the ringing signal; therefore, in the embodiment of the present invention, "differentiability" is applied in clipping detection to determine whether the waveform is clipped, so as to remove the influence of the amplitude and frequency of the ringing signal.

[0092] For any point x=c on the function f(x), we can define equation (4):

[0093]

[0094] Among them, f′ -c is the left limit of the function f(x) when x=c, f′ +c is the right limit of the function f(x) when x=c.

[0095] Assume that, formula (5) f′ -c ≠f′ +c , then the function f(x) is non-differentiable (or discontinuous) at x=c.

[0096] In actual clipping detection, in order to further consider the impact of environmental noise, equation (5) can be further modified as follows:

[0097] If, formula (6) |f′ -c -f′ +c |≥CMP_THD, then f(x) is non-differentiable at x=c and clipping occurs.

[0098] The following describes the operation of the voltage detection and limit determination unit 403 in performing voltage detection and limit determination in combination with the above-mentioned equations (4) to (6).

[0099] As mentioned previously ( Figure 4), the voltage detection and limit determination unit 403 may include a voltage detection unit 403a, a low-pass filter 403c, and a limit determination unit 403b. The voltage detection unit 403a is coupled to the user loop 406, and monitors to obtain the voltage waveform of the ringing signal RS (as mentioned above, for example, the voltage waveform of the Ring signal of the user loop 406). In this embodiment, the voltage detection unit 403a monitors the Ring signal of the ringing signal, not its peak voltage. In addition, the voltage detection unit 403a samples the Ring signal voltage waveform for at least 1 cycle, and the sampling frequency (for example but not limited to) may be 8k~16k Hz.

[0100] The voltage waveform of the Ring signal obtained by sampling is further filtered out by a low-pass filter 403c to remove high-frequency noise, and then input into the limit determination unit 403b.

[0101] As mentioned above, the limit determination unit 403b may include a limit calculator 403b1 and a comparator 403b2. The limit calculator 403b1 receives a voltage waveform (e.g., a voltage waveform of a Ring signal) and calculates the left limit and the right limit of each point of the voltage waveform according to the above formula (4). Then, for each point, the comparator 403b2 performs a comparison based on the above formula (6) and converts |f′ -c -f′ +c | is compared with the received set threshold COMP_THD to determine whether clipping occurs. Note that the set threshold COMP_THD can be a fixed value, which can be set to 0.3-0.5. This is only an example and the present invention is not limited thereto. In other words, if there is any point that meets the condition of formula (6): |f′ -c -f′ +c |≥COMP_THD, the comparator 403b2 determines that the ringing signal has limited amplitude. At this time, the comparator 403b2 will further send a gain adjustment signal RGA to the ringing gain adjuster 402a and the ringing driver 402b of the ringing signal adjustment and driving unit 402, so as to attenuate the ringing signal RS and output it to the user loop 406.

[0102] Figure 6 and Figure 7 Displays the simulation results of clipping detection.

[0103] Figure 6 Line 601 represents the ringing signal waveform. Taking the Ring signal as an example, line 602 represents the difference between the right limit and the left limit of each sampling point (detection point) of the ringing signal waveform (|f′ -c -f′ +c |). Figure 6The frequency of the ringing signal is 100 Hz, and the normalized peak-to-peak value (corresponding to the ringing amplitude) is 1.8. From the simulation results, it can be seen that relative to the region where the waveform shown in line 601 is not limited, the |f′ shown in line 602 is -c -f′ +c | is less than 0.4; relative to the waveform turning point shown by line 601, |f′ shown by line 602 -c -f′ +c |Exceeds 0.8.

[0104] Figure 7 Line 701 represents the ringing signal waveform, and line 702 represents the difference between the right limit and the left limit of each sampling point (detection point) of the ringing signal waveform (|f′ -c -f′ +c |). Figure 7 The frequency of the ringing signal is 200 Hz, and the normalized peak-to-peak value (corresponding to the ringing amplitude) is 1.0. From the simulation results, it can be seen that relative to the area where the waveform shown in line 701 is not limited, the |f′ shown in line 702 -c -f′ +c | is less than 0.4; relative to the waveform turning point shown on line 701, |f′ shown on line 602 -c -f′ +c |Exceeds 0.8.

[0105] from Figure 6 and Figure 7 The simulation results show that the ringing signal amplitude limiting detection device of the present invention can eliminate the dependence on the ringing amplitude and the ringing frequency. Therefore, a unified (or fixed) comparison threshold value (COMP_THD) can be applied to ringing signals of all frequencies and all amplitudes.

[0106] The words "first", "second", "third", etc. are used in the scope of the patent application to modify the elements in the scope of the claims. They are not used to indicate a priority order, a prior relationship, or that one element precedes another element, or a time sequence when performing method steps. They are only used to distinguish elements with the same name.

[0107] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the scope of the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope of the claims.

Claims

1. A ringing signal limit detection device, characterized in that: include: A ringing generator generates a ringing signal according to the ringing parameters; A ringing signal adjustment driving unit receives the ringing signal and a gain adjustment signal, attenuates the gain of the ringing signal or maintains the gain of the ringing signal according to the gain adjustment signal, and then outputs the ringing signal to the user loop; and A voltage detection and amplitude limiting judgment unit is coupled to the user loop, detects the voltage waveform of the user loop, or the voltage waveform corresponding to the ringing signal, and judges whether the ringing signal is amplitude limited according to whether the detected voltage waveform is discontinuous; When it is determined that the ringing signal is limited, the voltage detection and limit determination unit drives the ringing signal adjustment driving unit to attenuate the ringing signal through the gain adjustment signal.

2. The ringing signal amplitude limiting detection device as claimed in claim 1, characterized in that: The voltage detection and limit determination unit includes: A voltage detection unit, detecting and obtaining the voltage waveform; and The limit judgment unit is configured as follows: For each detection point of the voltage waveform, calculating the left limit and the right limit of the detection point; Determine whether the difference between the left limit and the right limit is greater than or equal to a set threshold value; When the difference between the left limit and the right limit is greater than or equal to the set threshold value, the voltage waveform is determined to be discontinuous; and In response to the determination that the voltage waveform is discontinuous, the gain adjustment signal is sent to drive the ringing signal adjustment driving unit to attenuate the ringing signal.

3. The ringing signal amplitude limiting detection device as claimed in claim 2, characterized in that: in The voltage detection and limit determination unit further includes: The low-pass filter is coupled between the voltage detection unit and the amplitude limiting determination unit to perform low-pass filtering on the voltage waveform and then output it to the amplitude limiting determination unit.

4. The ringing signal amplitude limiting detection device as claimed in claim 2, characterized in that: The above-mentioned limit determination unit comprises: a limit calculator, receiving the voltage waveform to calculate the left limit and the right limit of the detection point; and The comparator compares the difference between the left limit and the right limit with the set threshold value; when the difference is greater than or equal to the set threshold value, the gain adjustment signal is sent to drive the ringing signal adjustment driving unit to attenuate the ringing signal.

5. The ringing signal amplitude limiting detection device as claimed in claim 4, characterized in that: When the difference is smaller than the set threshold value, the comparator drives the ringing signal adjustment driving unit to keep the gain of the ringing signal at 0 dB through the gain adjustment signal.

6. The ringing signal amplitude limiting detection device as claimed in claim 1, characterized in that: The voltage waveform of the above-mentioned ringing signal is a tip voltage waveform or a round end voltage waveform.

7. The ringing signal amplitude limiting detection device as claimed in claim 6, characterized in that: The above-mentioned round end voltage waveform is a sine waveform, and the above-mentioned tip voltage waveform is a cosine waveform.

8. The ringing signal amplitude limiting detection device as claimed in claim 2, characterized in that: The above-mentioned threshold value is a fixed value.

Images