JPH05336102A - Burst discrimination circuit - Google Patents

Abstract

PURPOSE:To provide the burst discrimination circuit being able to surely discriminate whether a detected power is a burst signal or noise and detecting only the burst signal. CONSTITUTION:The circuit is provided with an amplitude detection section 1 sampling a burst signal having a fixed preamble and outputting an amplitude at each sampling point, a power calculation section 2 calculating an average power from the amplitude outputted sequentially from the amplitude detection section 1, a change component calculation section 3 calculating a time change component as to the average power calculated by the power calculation section 2, a 1st comparator section 4 detecting that the average power exceeds a 1st threshold level, a 2nd comparator section 5 detecting that a time change of the average power is lower than the 2nd threshold level, and a discrimination section 6 discriminating whether an interface is a head of the burst signal or noise based on the result of detection of the 1st and 2nd comparator sections 4, 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burst transmission / reception system having a fixed preamble, and more particularly to a burst judgment circuit for judging whether detected power is burst or noise.

[0002]

2. Description of the Related Art Conventionally, in a burst transmission / reception system such as packet transmission, the power at each sampling point is calculated and the burst head is detected when the power exceeds a certain threshold.

However, such a conventional burst head detection method has a drawback that noise and burst head cannot be distinguished. That is, it is necessary to set the threshold value low in order to reliably detect the burst, but the probability of false detection due to noise increases. Conversely, if you set a high threshold to avoid false detection due to noise,
This time, the burst signal with low power density is missed.

[0004]

As described above, it has been difficult in the past to reliably distinguish the burst head from noise.

The present invention has been made in order to solve the above problems, and provides a burst judgment circuit capable of surely judging whether the detected power is burst or noise and detecting only burst. The purpose is to

[0006]

In order to achieve the above object, a burst judgment circuit according to the present invention comprises an amplitude detector for sampling a burst signal having a fixed preamble and outputting an amplitude value at each sampling point, and an amplitude detector. A power calculation unit that calculates an average power value from amplitude values sequentially output from the detection unit, a change amount calculation unit that calculates a time change amount of the average power value calculated by this power calculation unit, and the average power value is A first comparing unit that detects that the average power value has exceeded a first threshold value; and a second comparing unit that detects that the time change of the average power value has dropped below a second threshold value; Two
And a determination unit that determines whether the input signal is the burst head or the noise based on the detection result of the comparison unit.

[0007]

In the burst judgment circuit having the above structure, when the burst signal is input, the average power value becomes equal to or higher than the first threshold value,
By utilizing the fact that the amount of change with time falls below the second threshold value, it is determined that the burst head is detected when both are detected.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the configuration of a burst judgment circuit according to the present invention. In FIG. 1, when the burst signal IN having a fixed preamble is input to the amplitude detection unit 1, the amplitude detection unit 1 samples the input burst signal and outputs the amplitude value at each sampling point.
The sampled amplitude value is supplied to the power calculation unit 2. The power calculator 2 calculates a power value from the input amplitude value and then integrates it m times (m is an arbitrary natural number) to calculate the average value. The average value obtained by the power calculator 2 is supplied to the change calculator 3 and the power threshold comparator 4 as an average power value.

The change detecting section 3 obtains the time change of the average power by taking the difference between the input average power value and the previous average power value. This time change is the average time change threshold comparator 5
Is supplied to. The comparator 5 detects that the time change of the input average power changes from a threshold value or more set in advance to a threshold value less than the threshold value. This detection information is sent to the determination unit 6.

On the other hand, the power threshold comparator 4 compares the preset power threshold with the input average power value, and outputs the detection information when it detects that the input average power value exceeds the threshold. This detection information is also sent to the determination unit 6. When the detection information is supplied from both of the comparators 4 and 5, the determination unit 6 determines that the burst head is reached. The result of this determination is sent to a burst signal processing unit (not shown).

In the above configuration, when a burst signal is input, the average power value rises linearly as shown in FIG. 2 (a) and becomes constant at a certain level. If the threshold value of the comparator 4 is set relatively low, the burst head can be detected with certainty. However, as described above, erroneous detection due to noise is likely to occur, so here, it is determined whether the detection result is burst or noise by looking at the time change of the average power value.

That is, as for the time change of the average power value when the burst signal is input, as shown in FIG. 2B, a level corresponding to the rising slope appears when the burst signal rises. When the noise is averaged, the level drops, and there is almost no change over time. Therefore, the change amount calculation unit 3 obtains the average power change amount, and the comparator 5 sets a threshold value based on the possible rise change of the burst signal.
If it is detected that the time change is less than the threshold value, it can be determined that the detection output of the power threshold value comparator 4 is the detection of the burst head.

Therefore, even if the threshold value is set low in order to reliably detect the beginning of the burst, the burst determination circuit having the above-mentioned configuration can determine whether the detection is an erroneous detection due to noise. Only will be able to detect.

Here, as shown in FIG. 3, the average power value output from the power calculating unit 2 is passed through a filter 7 adapted to a fixed preamble and supplied to a change amount calculating unit 3 and a power threshold comparator 4. To do so. Time constant τ of filter 7
To match the sampling cycle of the amplitude detector 1. According to this configuration, the average power value output from the filter 7 is updated for each time constant τ as shown in FIG.
Since the average power time variation is also calculated for each time constant τ,
It is possible to further reduce the influence of noise.

In each of the above embodiments, the averaging process in the power calculation unit 2 is to prevent the variation of the average power value over time, and the present invention is not limited to this. The same effect can be obtained regardless of whether the amplitude value, the power value, or the power value change with time. Needless to say, various modifications can be made without departing from the scope of the present invention.

[0017]

As described above, according to the present invention, it is possible to provide a burst judgment circuit which can surely judge whether the detected power is burst or noise and can detect only burst.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing the configuration of an embodiment of a burst determination circuit according to the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the embodiment of FIG.

FIG. 3 is a block circuit diagram showing the configuration of another embodiment according to the present invention.

FIG. 4 is a waveform chart for explaining the operation of the embodiment of FIG.

[Explanation of symbols]

1 ... Amplitude detection unit, 2 ... Power calculation unit, 3 ... Change calculation unit,
4 ... Power threshold comparator, 5 ... Average power change threshold comparator,
6 ... Judgment part, 7 ... Filter.

Claims (2)

[Claims] 1. An amplitude detector for sampling a burst signal having a fixed preamble and outputting an amplitude value at each sampling point, and a power calculator for calculating an average power value from the amplitude values sequentially output from the amplitude detector. A change amount calculation unit that calculates a time change amount of the average power value calculated by the power calculation unit, a first comparison unit that detects that the average power value exceeds a first threshold value, and the average The second detecting that the time change of the power value has dropped below the second threshold value
And a determination unit that determines whether the input signal is the burst head or noise based on the detection results of the first and second comparison units. 2. An average power value obtained by the power calculation unit at a time constant that matches a sampling cycle of the amplitude detection unit, and the average power value obtained by the power calculation unit at the time constant interval is compared with the variation calculation unit and the first comparison unit. The burst determination circuit according to claim 1, further comprising a filter for supplying the burst determination circuit.