JPS6260327A - Transmission quality decision system - Google Patents

Abstract

PURPOSE:To improve the decision accuracy and stability by using a discriminating means setting the threshold value of the 1st and 2nd bit error rate in advance in response to the rated quality of the transmission system to decide the deterioration and recovery in the quality of the transmission system. CONSTITUTION:The bit error rate (=5/1,000 or 3/600) is set as the 1st threshold value when it is decided as the deterioration quality when the error bit number is, e.g., 5-bit or over. Further, the bit error rate (=3/1,000) is set as the 2nd threshold value so that it is decided as the quality recovery when the error bit number is 3-bit or below after the deterioration of quality is decided. When the counted value of the error bit reaches 3-bit, a count output signal ECO is generated from an error bit count circuit 20. Thus, an alarm output control circuit 30 outputs a set signal SO and a reset signal RS of a counted value to set an alarm latch circuit 40 thereby generating an alarm signal AL. Further, each count is reset respectively to a digital signal bit count circuit 10 and an error bit count circuit 20.

Description

DETAILED DESCRIPTION OF THE INVENTION C. Technical Field of the Invention The present invention relates to an improvement in a transmission quality determination method for determining the quality of a transmission system based on the bit error rate of a transmitted digital signal in a digital transmission device.

[Technical background of the invention]

Conventionally, as this type of method, for example, all bits of a transmitted digital signal are counted, error bits in the digital signal are counted, and the bit error rate (number of error bits/total number of counted bits) is calculated from these counted values. There is a system that determines the quality and when this value exceeds a predetermined threshold value, it is determined that the quality has deteriorated and an alarm is generated. FIG. 3 shows the configuration of a quality determination circuit to which this method is applied. This circuit includes a digital signal bit counting circuit 1 that counts digital signal bits CK, an error bit counting circuit 2 that counts error bits ER, It is comprised of a memory circuit 3 which latches and outputs the alarm signal AL generated from this error bit counting circuit o2. Then, until the digital signal bit counting circuit 1 counts a predetermined number of bits (for example, 1000 bits), that is, until the count value of the counting circuit 1 reaches an overflow state and the reset signal @R8 is output. When the count value of the error bit counting circuit 2 exceeds a preset threshold (for example, 4 bits), an alarm signal AL is generated. If the count value of bit counting circuit 2 decreases to less than 4 bits, alarm signal A is activated.
I'm trying to turn off L. In other words, this conventional method generates an alarm when the bit error rate of the digital signal exceeds the bit error rate threshold determined by the maximum counts of the digital signal bit counting circuit 1 and the error bit counting circuit 2. , and the generation of an alarm is stopped when the bit error rate returns to below the threshold value.

[Problems with background technology]

However, in such conventional quality judgment methods, the bit error rate threshold is fixed to one, so depending on the threshold value, for example, if the quality of the transmission system temporarily deteriorates, this may occur. This method has the disadvantage that it is determined that there is an immediate quality deterioration, and the transmission operation is interrupted even though the actual transmission is not so affected. In addition, if you set the threshold value to a large value in order to eliminate this kind of drawback, this will result in a problem where if the quality deterioration is determined and then the error rate temporarily decreases, this will be determined to be an immediate recovery. This was extremely undesirable.

[Purpose of the invention]

The present invention makes it possible to reliably judge only the quality deterioration that should have been detected, and also to release the quality deterioration state after the quality has been reliably restored. The purpose of this invention is to provide a transmission quality determination method that enables transmission.

(Summary of the Invention) In order to achieve the above object, the present invention includes a first counting means for counting the number of pits of a transmitted digital signal, and a second counting means for counting error bits of the digital signal. , a determination means in which first and second bit error rate thresholds are set in advance according to the rated quality of the transmission system, and this determination means determines the bits obtained from the counts of the respective counting means in steady state. When the error rate exceeds the first bit error rate, it is determined that the quality of the transmission system has deteriorated, and after determining the quality deterioration, the bit error rate calculated from the count value of each counting means (q) It is determined that the quality deterioration of the transmission system continues until the bit error rate falls below 2.

(Embodiment of the Invention) FIG. 1 shows the configuration of a quality determination circuit to which a transmission quality determination method is applied in an embodiment of the present invention.
, an alarm output control circuit 30, and an alarm latch circuit 40 consisting of a flip-flop. The digital signal bit counting circuit 10 has two different maximum count values.
These counters each count the bits of the digital signal CK, and when the counted value reaches the maximum counted value, each counter outputs a count output signal Co of ゛H' level.
``1, which generates CO2.

The error bit counting circuit 20 counts error bits in the digital signal and generates a count output signal ECO when the counted value reaches a preset value. The alarm output control circuit 3o is composed of a logic gate circuit, and has inputs CO1, CO2, and ECO as shown in the following table.
, ALk: generates a pair of 16 outputs So, RO, R8. Of these outputs, So and RO are a set signal and a reset signal respectively supplied to the alarm latch circuit 40, and R8 is for resetting each count value of the digital signal bit counting circuit 10 and error bit counting circuit 20. This is the signal. Note that the operation indicated by X in the table is for the case where the maximum count values of each counter of the digital signal counting circuit 10 are integer multiples, for example, 1000.500.

Incidentally, the operation indicated by
This is a case where the relationship is an integral multiple, such as 00.

By the way, in the method of this embodiment, two different bit error rate thresholds are set depending on the rated quality of the transmission line used. For example, if we use a transmission line that has the characteristics shown in Figure 2, where the probability of occurrence of an error bit in a given bit of a digital signal (for example, 1000 bits) is 5 or more, The bit error rate is -5/1 so that it can be determined that the quality has deteriorated.
000 = 3/600 is set as the first threshold /II, and after determining that the product has degraded by 1τ, the number of error bits is 3.
The bit error rate -3/1000 is set as the second threshold so that it can be determined that the quality has been restored when the bit error rate decreases to less than 1 bit. In this circuit, the threshold value of these bit error rates is set to 3.
while the digital signal bit counting circuit 10
As mentioned above, two counters are provided, and the maximum count values of these counters are set to 600 and 1000, respectively. In other words, two bit error rate thresholds are set by determining the bit error rate (number of error bits/total number of bits) by varying the total number of pits.

With this configuration, in a steady state where no alarm is generated, that is, when the quality of the transmission line is relatively good, the alarm output control circuit 30 controls the count output signal output from the digital signal bit counting circuit 10. I am trying to monitor CO2.

That is, line quality is monitored using a bit error rate of -3/600 as a threshold. Therefore, even if the number of error pins increases temporarily in this state, the threshold value of the bit error rate is set to a large value, so this is prevented from being determined as an immediate quality deterioration.

Now, in the steady state described above, if the quality of the transmission line deteriorates for some reason and the number of error bits increases, when the count of error bits reaches 3 bits, the error bit counting circuit 20 outputs the count output signal ECO. is generated. Then, the alarm output control circuit 3o outputs the set signal so and the reset signal R8 for the count value at the time when the ECO is generated, as shown in A above, and sets the alarm latch time 840 due to the mouth movement to output the alarm signal. In addition to generating AL, the digital signal bit counting circuit 10
and each count value of the error bit counting circuit 20 is reset. By this reset, the digital signal bit counting circuit 1o and the error bit counting circuit 2o immediately restart counting operations. Then, if the error bit counting circuit 2o generates the counting output signal ECO again before each counter of the digital signal bit counting circuit 1o generates the counting output signals CO1, CO2, the alarm output control circuit 30 displays the As shown in the opening, the set signal SO and the reset signal □ R8 for setting the count value υ are generated again, and each counting circuit 10 is thereby activated while maintaining the alarm generation.
．． Repeat the quality monitoring in step 20.

On the other hand, during the monitoring operation in this alarm generation state, that is, in a state where the line quality is degraded, the alarm output control circuit 3
0 sets the bit error rate threshold to the smaller threshold (3
゜/1000). Therefore, in this state, the number of generated apology bits temporarily decreases, and as a result, the count value of the counter of the digital signal bit counting circuit 10 reaches 600 before the counting output signal ECO is generated from the error bit counting circuit 20. , even if the count output signal GO2 is generated, the alarm output control circuit 30 does not generate the alarm set signal RO as shown in C of the table above, and therefore the output of the alarm signal AL is not stopped and the digital signal pitch is 1 to counting circuit 10 and error bit counting circuit 20 each continue counting operations.

- 10,000, if the quality of the line is completely restored in this state and the count output signal CO1 is generated from the digital signal bit counting circuit 10 before the count output signal ECO is generated from the error bit counting circuit 20, then At this point, the alarm output control circuit 30 generates a reset signal @RO and a signal R8 for resetting the count value as shown in Table 2, thereby resetting the alarm latch circuit 40 and stopping the generation of the alarm signal AL. . That is, the alarm continues to be generated until the line quality is sufficiently restored.

In this example, two bit error rate thresholds with different sizes are set, and these thresholds are used to determine whether an alarm has occurred, that is, whether the line quality has deteriorated. Since it is used selectively depending on the quality, the quality judgment operation can have hysteresis characteristics. Therefore, the threshold value for determining quality deterioration can be set higher than before, and as a result, even if a temporary increase in error bits occurs during steady state, this can be immediately determined as line quality deterioration. This can be prevented. In addition, after an alarm occurs, the threshold value for determining whether the line quality has recovered to normal status can be set smaller than before, and as a result, the line quality temporarily recovers. It is possible to prevent a problem in which this is determined to be an immediate line quality recovery when the line quality is restored, and it is possible to stop generating an alarm after the line quality has been reliably recovered. Therefore, stable and reliable quality determination can be performed, thereby significantly increasing transmission efficiency.

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, the first and second bit error rate thresholds are set by providing two counters in the digital signal bit counting circuit 10 and making the maximum count values of these counters different. , the digital signal bit counting circuit 10 may have only one counter, and the error bit counting circuit 20 may be set with two thresholds for detecting the number of error bits instead.

Further, in the embodiment, the digital signal pit counting circuit 10
However, by combining one counter and a logic gate circuit, count output signals COI and CO2 of the fiHII level are generated respectively at two different count values. Good too.

In addition, the threshold value of the bit error rate, the configuration of each counting means and determination means, the configuration of the means for displaying the determination result of quality deterioration, etc. may be modified in various ways without departing from the gist of the present invention. I can argue.

〔Effect of the invention〕

As detailed above, according to the present invention, the first counting means counts the number of bits of the transmitted digital signal, the second counting means counts the error bits of the digital signal,
A determination means is provided in which first and second bit error rate thresholds are set in advance according to the quality of the transmission system, and this determination means determines the bits obtained from the counts of each of the counting means in steady state. When the error rate exceeds the first bit error rate, it is determined that the quality of the transmission system has deteriorated, and after the quality deterioration determination in parentheses, the bit error rate calculated by 1q from the count head of each counting means is the second bit error rate. By determining that the quality deterioration of the transmission system continues until the bit error rate falls below the bit error rate of Once the quality is recovered, the quality degradation state can be canceled, and as a result, it is possible to provide a transmission quality determination method that provides highly efficient digital transmission with high determination accuracy and stability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a quality judgment circuit to which a transmission quality judgment method according to an embodiment of the present invention is applied, FIG. 2 is a characteristic diagram showing an example of the probability of occurrence of the number of error bits in a transmission line, and FIG. The figure is a block diagram showing the configuration of a quality determination circuit to which a conventional transmission quality determination method is applied. 10... Digital signal bit counting circuit, 20... Error bit counting circuit, 30... Alarm output control circuit,
40... Alarm latch circuit, GK... Digital signal, ER... Error bit, COl, CO2... Count output signal of digital signal bit counting circuit, ECO...
Count output signal of the error bit counting circuit, So... Sera 1 ~ signal for alarm generation control, RO... Reset signal for alarm generation control, R8... Reset signal for counting value reset, AL...・Alarm signal. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (3)

[Claims] (1) In a transmission quality determination method that determines the quality of a transmission system from the bit error rate of a transmitted digital signal, a first counting means for counting the number of bits of the digital signal; and a number of error bits in the digital signal. and a first and second bit error rate threshold set in advance according to the rated quality of the transmission system, and in a steady state, the first and second counting means When the bit error rate obtained from the count value exceeds the first bit error rate, it is determined that the quality of the transmission system has deteriorated, and after this quality deterioration determination, the first and second counting means 1. A transmission quality determination method, comprising: determination means for determining that the quality deterioration state of the transmission system continues until the bit error rate obtained from the counted value becomes equal to or less than the second bit error rate. (2) The determining means sets the first and second bit error rate thresholds by switching between two predetermined maximum counts of the first counting means. Transmission quality determination method described in ). (3) The determination means sets the first and second bit error rate thresholds by switching between two predetermined maximum counts of the second counting means. Transmission quality determination method described in ).