CN102202025B - Method for pulse interference detection and elimination - Google Patents

Abstract

The invention discloses a method for pulse interference detection and elimination. The method comprises the following steps: step one, pulse interference detection: recording absolute values and Sum (n)s of orthogonal data of path I and path Q, finding out a maximum Sum (n) and a minimum Sum (n) of a present frame, and recording the maximum Sum (n) as MaxVal and the minimum Sum (n) as MinVal respectively; recording found sequence numbers MaxIdx and MinIdx respectively corresponding to the MaxVal and MinVal in the present frame; if (MaxVal-MinVal) / (MaxIdx-MinIdx) is greater than Slope, and (MaxIdx-MinIdx) is also greater than Width, there being pulse interference with an interference interval of [MinIdx, MaxIdx]; otherwise, there being no pulse interference; and step two, pulse interference elimination: selecting an offset interval of pulse interference, chasing a sampling point, and comparing the sampling point with MeanSum*ThreRatio within the selected offset interval. According to the invention, whether there is pulse interference or not can be detected effectively, and performance loss caused by the pulse interference can be reduced. Therefore, the method for pulse interference detection and elimination provided in the invention is suitable for all data communication systems.

Description

Impulse disturbances detects and removing method

Technical field

The present invention relates to data communication field, particularly relate to a kind of impulse disturbances for data communication system and detect and removing method.

Background technology

Under current multiband data communication system and the situation of depositing, the situation that often can occur interfering with each other.The TDD system will present the characteristic of burst for the received terrestrial digital broadcasting system.

The ability of Europe DVB system counter impulse disturbances has been made clear and definite requirement.CNS DTMB ground system of digital television broadcast also resists impulse disturbances and has proposed concrete requirement.

Consider from the testing standard angle, so-called impulse disturbances refers to intermittent Gaussian noise, in noisy time interval, has continuous characteristic, and this Gaussian noise can be flooded signal.Be subjected to the part signal of Gauusian noise jammer, show as a projection or large-signal amplitude intensive on time domain.

In existing DVB-T system impulse disturbances detect suppress module structure as shown in Figure 1, the data buffer storage of A/D (analog-to-digital conversion) transducer output is in buffer, starting position and interference length that detector detects after impulse disturbances impulse disturbances send inhibitor to, and inhibitor is taken out data and suppressed to process from buffer.

In existing DVB-T system, impulse disturbances detects with the method for eliminating specific implementation and is: calculate with the moving average method average energy mean_power that the N of A/D converter output is ordered.Pointwise compares the energy of each point and product a * mean_power of average energy mean_power and coefficient a (the slicing factor).In case find that the energy of certain point greater than a * mean_power, records this position, open simultaneously a counter in order to record interference length.When below having satisfied during two conditions, think and found impulse disturbances:

(1) energy of continuous m frame is all lower than a * mean_power.

(2) interference length that detects disturbs the interior average energy of section greater than p greater than q.

Wherein, a, q, m, p are the threshold values that can configure.

After impulse disturbances being detected, send original position and the interference length of impulse disturbances to inhibitor, and adopt following methods that interference is suppressed:

$y=\left\{\begin{array}{cc}\mathrm{cx}& x<a\&times;\mathrm{sigma}\\ \mathrm{ca}\&times;\mathrm{sigma}& x>=a\&times;\sin \mathrm{ma}\end{array}\right.$

Wherein, y is that x is the data that impulse disturbances is crossed through the interfering data after suppressing, and sigma is the average root of mean_power, perhaps the standard deviation of data x; A is the slicing factor, and c is zoom factor.When c is made as 0, be equivalent to the point that impulse disturbances is crossed is set to 0.

In existing DVB-T system, impulse disturbances detects and removing method, a, and q, m, p need to suitably choose, and probability of miscarriage of justice is higher, needs extra storage, and implementation complexity is larger.

Summary of the invention

Whether the technical problem to be solved in the present invention is to provide a kind of impulse disturbances and detects and removing method, can effectively detect impulse disturbances and exist, and reduce the performance loss that is brought by impulse disturbances.

For solving the problems of the technologies described above, it is to adopt following technical scheme to realize that impulse disturbances of the present invention detects with removing method:

Step 1, impulse disturbances detects;

The I of input, Q two-way orthogonal data records I through after the frame head position synchronously being detected, and the absolute value of Q two-way orthogonal data and Sum (n) find maximum Sum (n) and minimum Sum (n) in present frame, are designated as respectively MaxVal, MinVal; The MaxVal that record finds, MinVal be corresponding sequence number MaxIdx in present frame, MinIdx; If before present frame finishes,

(MaxVal-MinVal)/(MaxIdx-MinIdx)＞Slope

(MaxIdx-MinIdx)＞Width

There is impulse disturbances, and is [MinIdx, MaxIdx] between interference range; Otherwise there is not impulse disturbances;

Wherein, Slope is configurable slope threshold, and Width is configurable pulse duration thresholding;

Step 2, impulse disturbances is eliminated;

Choose between the impulse disturbances bucking block, between the bucking block of choosing in, compare by sampled point and MeanSum * ThreRatio; Wherein, MeanSum is current frame data part I, Q two-way orthogonal data absolute value and average,

ThreRatio is the nonnegative number less than 1, configurable threshold value.

Method of the present invention is very effective for the signal that detection has projection (or local value amplitude distribution density changes) feature; Due to search be extreme value place, thereby can not be subject to the impact that the discrete pulse of low probability disturbs and cause erroneous judgement.

Method of the present invention can effectively reduce continuous impulse and disturb the impact that useful signal is caused by adjusting ThreRatio.

Adopt method of the present invention can effectively detect impulse disturbances and whether exist, and reduce the performance loss that is brought by impulse disturbances.Method of the present invention is not limited to the DTMB system, is applicable to all data communication systems.

Description of drawings

The present invention is further detailed explanation below in conjunction with accompanying drawing and embodiment:

Fig. 1 is that in existing DVB-T system, impulse disturbances detects the structure chart that suppresses module;

Fig. 2 is impulse disturbances detection algorithm schematic diagram;

Fig. 3 is the impulse disturbances overhaul flow chart.

Embodiment

In impulse disturbances detection of the present invention and removing method one embodiment, comprise that impulse disturbances detects and impulse disturbances is eliminated two steps.

Step 1, impulse disturbances detects.Impulse disturbances detection algorithm schematic diagram as shown in Figure 2.

PN part is under PN420 and PN945 situation in CNS DTMB, and average power exists 3dB to strengthen, for avoiding that it is mistaken for impulse disturbances, and with the multiplexing cover resource of PN595, only carry out the impulse disturbances detection with non-PN data.

The input data are time domain I, and Q two-way orthogonal data is designated as I (n), Q (n).After the frame head position synchronously being detected, record I with an accumulator, the absolute value of Q two paths of data and, that is,

Sum (n)=Sum (n-1)+D (n)-threshold (formula 1)

Wherein D (n)=| I (n) |+| Q (n) |, threshold is pre-configured detection threshold value.Be updated in maximum Sum (n) and the minimum Sum (n) that obtains in present frame with two registers, be respectively MaxVal, MinVal; With the MaxVal that two register records find, MinVal is corresponding sequence number MaxIdx in present frame, MinIdx; If before present frame finishes, find two such points, make

(MaxVal-MinVal)/(MaxIdx-MinIdx)＞Slope (formula 2)

(MaxIdx-MinIdx)＞Width (formula 3)

Wherein, Slope is configurable slope threshold, and Width is configurable pulse duration thresholding.So, think to have impulse disturbances, and be [MinIdx, MaxIdx] between interference range; Otherwise think and do not have impulse disturbances.

The flow chart that impulse disturbances detects as shown in Figure 3.Wherein, L is the length (the DTMB standard frame is made of PN part and data division) of an intraframe data part in the DTMB standard.N is current sampling point in the sequence number of a frame data part, and pulse_flag indicates whether to find impulse disturbances, and pulse_flag=1 represents to find impulse disturbances.

Step 2, impulse disturbances is eliminated.After finding the impulse disturbances interval, carry out impulse disturbances and eliminate.Eliminate impulse disturbances and need to choose between the impulse disturbances bucking block, selection scheme between two kinds of impulse disturbances bucking blocks is arranged: only offset in step 1 finds impulse disturbances interval (1).(2) offset in the whole frame of the frame that has impulse disturbances.

After choosing between bucking block, between the bucking block of choosing in, compare by sampled point and MeanSum * ThreRatio.Wherein, MeanSum is current frame data part I, Q two-way orthogonal data absolute value and average, ThreRatio is the nonnegative number less than 1, configurable threshold value.A configurable register can be set in actual use, multiply each other with MeanSum with the value (thresholding) of depositing in this configurable register, the actual door limit value is set flexibly.If this sampled point is greater than this thresholding ThreRatio, with this sampled point I, Q two-way orthogonal data multiply by the coefficient of reduction of a configuration simultaneously.

Abovely by embodiment, the present invention is had been described in detail, but these are not to be construed as limiting the invention.In the situation that do not break away from the principle of the invention, those skilled in the art also can make many distortion and improvement, and these also should be considered as protection scope of the present invention.

Claims (4)

1. an impulse disturbances detects and removing method, it is characterized in that: comprise the steps,

Step 1, impulse disturbances detects;

The I, Q two-way orthogonal data of input is through after the frame head position synchronously being detected, with an accumulator record I, Q two-way orthogonal data absolute value and, be Sum (n)=Sum (n-1)+D (n)-threshold, wherein D (n)=| I (n) |+| Q (n) |, threshold is pre-configured inspection threshold value, n is that current sampling point is in the sequence number of a frame data part, find maximum Sum (n) and minimum Sum (n) in present frame, be designated as respectively MaxVal, MinVal; The MaxVal that record finds, MinVal be corresponding sequence number Maxldx in present frame, Minldx; If before present frame finishes,

(MaxVal-MinVal)/(Maxldx-Minldx)＞Slope

(Maxldx-Minldx)＞Width

There is impulse disturbances, and is ［ Minldx, Maxldx ］ between interference range; Otherwise there is not impulse disturbances;

Wherein, Slope is configurable slope threshold, and Width is configurable pulse duration thresholding;

Step 2, impulse disturbances is eliminated;

Choose between the impulse disturbances bucking block, between the bucking block of choosing in, compare by sampled point and MeanSum * ThreRatio; Wherein, MeanSum be current frame data part I, Q two-way orthogonal data absolute value and average,

L is the length of an intraframe data part in the DTMB standard; ThreRatio is the nonnegative number less than 1, configurable threshold value.

2. the method for claim 1 is characterized in that: with the impulse disturbances interval as between the impulse disturbances bucking block.

3. the method for claim 1 is characterized in that: will exist the whole frame of frame of impulse disturbances as between the impulse disturbances bucking block.

4. the method for claim 1 is characterized in that: use non-PN data to carry out impulse disturbances in the DTMB system and detect.

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