JP2869284B2 - Signaling signal error protection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signaling signal error protection circuit, and more particularly to a signaling signal error protection circuit for performing error protection of a signaling signal in, for example, an analog interface of a transmission apparatus.

[0002]

2. Description of the Related Art One of signals transmitted or processed by a transmission device is described.
One is a signaling signal (S). This signal is, for example, a signal used in an exchange or the like, and notifies the opposing device that each channel is in use (S = 0), idle (S = 1), and blocked (S = 0). This is the signal to perform.

Conventionally, in such a transmission device,
The signaling signal is transmitted together with the main signal, the alarm signal, and the parity signal. That is, the normality of transmission data of these signals transmitted by the data bus (main signal, signaling signal, alarm signal) has been confirmed by monitoring the parity signal added to the signal.
In addition, the transmission device and data are transmitted by an alarm signal (normal:
Normality was confirmed in ALM = 0, abnormal: ALM = 1).

For example, if the alarm signal indicates ALM = 1 indicating an abnormality inside the transmission device, it is regarded as a device failure of the transmission device (including a transmission line failure between TDM and TDM, etc.) and connected to the transmission device. In this case, a blocking signal (S = 0) is notified to an external device such as a switchboard using a signaling signal.

[0005]

However, in such a conventional technique, even if an error of several bits occurs in the signaling signal inside the transmission device, if the parity error cannot be detected, the alarm signal is in the alarm state ( ALM
= 1), an erroneous signaling signal is transmitted to an external device such as an exchange.

An object of the present invention is to provide a signaling signal error protection circuit capable of eliminating the problem of sending such an erroneous signaling signal to an external device such as an exchange and transmitting a stable signaling signal. Aim.

[0007]

According to the present invention, in order to solve the above-mentioned problems, a signaling signal error protection circuit of an interface unit in a transmission apparatus for transmitting a signaling signal receives a received signaling signal and a reference clock,
A first protection circuit for determining the normality of the received signaling signal when the received signaling signal has undergone a first change, and receiving the received signaling signal and a reference clock, wherein the received signaling signal has the opposite polarity to the first change. A second protection circuit for determining the normality of the received signaling signal when a second change is made; and
When it is determined by the protection circuit and the second protection circuit that the received signal is normal, a transmission signaling signal corresponding to a change in the received signaling signal received by these protection circuits is sent out. A signaling signal transmitting circuit that transmits a transmission signaling signal that maintains a previous state without changing the signal.

[0008]

According to the present invention, the received signaling signal is the first
The normality of the received signaling signal is determined by the first protection circuit when the signal changes. If the signal is normal, the change in the received signaling signal is output from the signaling sending circuit as a transmission signaling signal. Also, when the received signaling signal makes a second change, the normality of the received signaling signal is determined by the second protection circuit. If the received signaling signal is normal, the change of the received signaling signal is transmitted from the signaling sending circuit as a transmission signaling signal. Is output. If the received signaling signal is determined to be abnormal by the first protection circuit or the second protection circuit, the signaling transmission circuit does not change the transmission signaling signal and transmits the transmission signaling signal maintaining the previous state. I do.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a signaling signal error protection circuit according to the present invention;

FIG. 3 shows an example of a relay system diagram of a communication system including a transmission device to which the signaling signal transmission circuit according to the present invention is applied. As shown in the figure, the present embodiment is, for example, a plurality of extension telephones 12A-1 to 12A.
Transmission devices 14A, 1 that connect a private branch exchange 10A that accommodates a plurality of extension telephones 12B-1 to 12B-n via a transmission line.
This is applied to the 4B analog interface unit.

FIG. 4 is a block diagram showing a connection example of the analog interface unit 16 between the exchange 10 and the transmission device 14 applied to the communication system of FIG. The analog interface unit 16 includes a VF DATA processing unit 18 that processes audio band signals transmitted and received by two or four wires.
And an SS / SR processing unit 20 connected to a signaling signal line (SR, SS) for processing a signaling signal. The SS / SR processing unit 20 is a signaling processing unit including the signaling signal error protection circuit in the present embodiment, and outputs a predetermined control signal to the VF DATA processing unit 18. These processing units 18 and 20 are connected to the multiplexing unit 22 in the transmission device.

FIG. 1 is a block diagram showing an embodiment of a signaling signal error protection circuit according to the present invention provided in the signaling processing unit 20 of FIG. As shown in the figure, in this embodiment, there are three input signals and one output signal.
The received signaling signal (hereinafter, referred to as an RSIG signal) indicates a signaling signal received from an opposite device, and the clock indicates a reference clock used for sampling the RSIG signal.

A transmission signaling signal (hereinafter referred to as SSI)
The G signal is an output signal of the RSIG signal after passing through the protection circuit. Further, the alarm signal is a signal indicating that the transmission device or the like has a failure. These three input signals are supplied to the front protection circuit 30 and the rear protection circuit 32, respectively.
Is input to

The forward protection circuit 30 determines whether the idle (S = 1) signaling signal received when the signaling signal is being used (S = 0) is a normal signal or an erroneous signal inside the apparatus. I do. Also, the rear protection circuit 32
Whether the used (S = 0) signaling signal received when the signaling signal is idle (S = 1) is a normal signal,
Determine whether the signal is incorrect inside the device. And
A signaling signal based on the determination result is sent from the front protection circuit 30 and the rear protection circuit 32 to the signaling signal sending circuit 34.

When the signaling circuit sending circuit 34 determines that these protection circuits have received an erroneous signal, the signaling signal sending circuit 34 sends an SSIG signal maintaining the previous state output from the protection circuit, and determines that a normal signal has been received. If it is determined, an SSIG signal with a changed signaling signal is transmitted. In this way, it is possible to prevent an erroneous signaling signal from being sent to an external device such as an exchange in the transmission device or on the transmission path. The circuit shown in FIG. 1 performs protection including sampling of the RSIG signal and conditions such as fault information indicated by the alarm signal.

FIG. 2 is a time chart showing an example of operation waveforms of the signaling data error protection circuit shown in FIG.
In Figure 2, it is roughly the operation by the four sections of T ₁ through T _4. That is, if T ₁ interval, if receiving the RSIG signal stably, T ₂ interval if an error occurs in the RSIG signal, T ₃ section that an error occurs in the RSIG signal and alarm signal, The section T ₄ shows the case where the alarm signal (ALM = 1) is received stably.

In this embodiment, as shown in FIG.
The SSIG signal is determined when the SIG signal is stably sampled for two clocks.

[0018] by T ₁ interval is stably receive the RSIG signal. Therefore, the fall of RSIG (“H” →
At “L”), the rear protection circuit 32 is used, and the SSIG signal that has received this change is output from the signaling signal transmission circuit 34 with a delay of T _D1 . Further, the front protection circuit 30 is used at the rise of RSIG (“L” → “H”),
_The SSIG signal that has received this change with a delay of _D2 is output from the signaling signal sending circuit 34.

As described above, the SSIG for the RSIG signal is
The G signal is output with a delay of _TD1 or _TD2 . The delays T _D1 and T _D2 are delays that occur when the RSIG signal is sampled, and the times are T _D1 = T _C + T _{G1 and} T _D1.
Represented by _D2 = T _C + T _G2. Here, T _{G1 and} T _G2 are R
This is the time from when the SIG signal changes to when it is first sampled with a clock, and T _C is the width of the clock used for sampling.

In addition, the width (T _C ) of the clock used for sampling is set to T width with respect to the width (T _W1,2 ) of the RSIG signal.
_{By setting W1,2} = AXT (A: natural number), T _D1 =
T _D2 (T _G1 = T _G2 ), and T _W1 = T _P1 and T _W2 = T _P2 . By _doing so, a normal waveform can be reproduced, _although a delay of T _{D1,2 occurs} .

In the section T _2, there is an error in the RSIG signal. However, the SSIG signal holds the previous state because the sampling by the clock is not performed twice stably.

In the section T ₃ , errors occur in the RSIG signal and the alarm signal. However, in this embodiment, RS
Since the same protection as that of the IG signal is performed on the alarm signal, the SSIG signal holds the previous state.

[0023] In T ₄ interval, the alarm signal indicates a stable (ALM = 1). Alarm signal is also RSIG
Since the same protection is performed as the signal, the SSIG signal is
After the protection time (T _D3 ), it is in the closed state (SSIG = 0).

In this embodiment, since a clock is used for the protection circuit, the circuit is more stable than a circuit including an error such as a resistor and a capacitor, such as a mono-multi circuit.

[0025]

As described above, according to the signaling signal error protection circuit of the present invention, it is possible to correct errors inside the transmission device and on the transmission line, and to reduce adverse effects on external devices such as exchanges.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a signaling signal error protection circuit according to the present invention.

FIG. 2 is a time chart showing an operation example in the embodiment of FIG. 1;

FIG. 3 is a relay system diagram of a communication system to which the present invention is applied;

FIG. 4 is a block diagram of an analog interface unit to which the present invention is applied.

[Explanation of symbols]

 Reference Signs List 20 signaling signal processing unit 30 forward protection circuit 32 backward protection circuit 34 signaling signal transmission circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-23636 (JP, A) JP-A-3-268652 (JP, A) JP-A-56-157162 (JP, A) JP-A-62 183234 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04M 3/22

Claims (2)

(57) [Claims] 1. A signaling signal error protection circuit of an interface unit in a transmission device for transmitting a signaling signal, comprising: receiving a received signaling signal and a reference clock; and when the received signaling signal undergoes a first change, the received signaling signal A first protection circuit for judging the normality of the received signaling signal, receiving the received signaling signal and the reference clock, and when the received signaling signal makes a second change opposite to the first change, A second protection circuit for determining the normality of the signal; and a reception signaling signal received by the first and second protection circuits when the received signaling signal is determined to be normal by the first and second protection circuits. Sends a transmission signaling signal according to the change in A signaling signal transmission circuit for transmitting a transmission signaling signal that maintains a previous state without changing a ring signal. 2. The signaling signal error protection circuit according to claim 1, wherein said first and second protection circuits input an alarm signal, determine the normality of the alarm signal, and determine whether the alarm signal is normal. A signaling signal error protection circuit, wherein an alarm signal is transmitted.