CN105163107A - Method for utilizing PCRs in DVB signal to detect symbol rate offset - Google Patents

Abstract

The invention discloses a method for utilizing PCRs in a DVB signal to detect symbol rate offset. The method includes the steps of: 1) obtaining a symbol rate of a DVB signal that is sent, and the obtaining a code rate Rb of the DVB signal according to the symbol rate of the DVB signal; 2) selecting any two PCRs in the DVB signal, then calculating a time difference [delta]t1 of arrival of the selected two PCRs according to the code rate Rb of the DVB signal that is obtained in the Step 1), and calculating a time difference [delta]t2 of arrival of the selected two PCRs according to information contained by the two PCR; and then calculating based on the time difference [delta]t1 and the time difference [delta]2 to see whether offset of the symbol rate occurs or not and obtain the type of the offset. The method for utilizing the PCRs in the DVB signal to detect the symbol rate offset can rapidly and accurately judge whether offset of the symbol rate occurs or not, is easy to operate, and has relatively low equipment requirements.

Description

One utilizes PCR detected symbol rate offset method in DVB signal

Technical field

The invention belongs to symbol rate offset detection field in DVB signal, relate to one and utilize PCR detected symbol rate offset method in DVB signal.

Background technology

In symbol rate offset detection process, we usually to adopt with a stable outside reference as reference, record the value of accurate external clock counter corresponding when receiving PCR, then calculate and judge whether symbol rate offsets, this method complicated operation is high to equipment requirement.

Summary of the invention

The object of the invention is to the shortcoming overcoming above-mentioned prior art, provide one and utilize PCR detected symbol rate offset method in DVB signal, the method can judge whether symbol rate offsets fast and accurately, and simple to operate, lower to equipment requirement.

For achieving the above object, in the DVB of utilization signal of the present invention, PCR detected symbol rate offset method comprises the following steps:

1) obtain the symbol rate sending DVB signal, then calculate the code check R of DVB signal according to the symbol rate of DVB signal _b;

2) choose DVB and entirely flow any two PCR in signal, then according to step 1) the code check R of DVB signal that obtains _bthe time difference Δ t that two PCR calculated arrive ₁, the information simultaneously comprised according to two PCR selected calculates the time difference Δ t of two the PCR arrival selected ₂;

As Δ t ₁> Δ t ₂time, then this result chosen is: the symbol rate generation negative bias of DVB signal moves; As Δ t ₁< Δ t ₂time, then this result chosen is: the symbol rate of DVB signal occurs just to offset; As Δ t ₁=Δ t ₂, then this result chosen is: the symbol rate of DVB signal offsets;

3) N-1 above-mentioned steps 2 is repeated), when there is the maximum probability that the symbol rate generation negative bias of DVB signal moves in the result to choose for N time, then the symbol rate generation negative bias of DVB signal moves; When occurring that in the result of N statistics the maximum probability just offset occurs the symbol rate of DVB signal, then the symbol rate of DVB signal occurs just to offset; When there is the maximum probability that the symbol rate of DVB signal do not offset in the result of N statistics, then the symbol rate of DVB signal does not offset.

The code check R of DVB signal is obtained according to the symbol rate of DVB signal _b, wherein,

R _b＝R _B*M*N

Wherein, M is the amount of information that any one symbol carries, and N is code efficiency, R _bfor symbol rate.

${\mathrm{\&Delta;t}}_1=\frac{i^{\&prime;}-i^{\&prime;\&prime;}}{R_b}$

${\mathrm{\&Delta;t}}_2=\frac{PCR\left(i^{\&prime;}\right)-PCR\left(i^{\&prime;\&prime;}\right)}{f}$

Wherein f is the clock frequency of system, i', i " be call number corresponding to bit byte that described two PCR fields are last.

f＝27MHz。

The present invention has following beneficial effect:

Of the present inventionly to utilize in DVB signal PCR detected symbol rate offset method in use, only two kinds of modes need be calculated the time difference contrast that two PCR arrive, whether the symbol rate that can obtain DVB signal accurately and rapidly there is the type offseting and offset, simple to operate, practicality is extremely strong.Do not need outside reference just can know the drift condition of symbol rate simultaneously, thus reduce the requirement to equipment, have broad application prospects.

Accompanying drawing explanation

Fig. 1 is flow chart of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail:

With reference to figure 1, in the DVB of utilization signal of the present invention, PCR detected symbol rate offset method comprises the following steps:

1) obtain the symbol rate sending DVB signal, then obtain the code check R of DVB signal according to the symbol rate of DVB signal _b, wherein

R _b＝R _B*M*N

Wherein, M is the amount of information that any one symbol carries, and N is code efficiency, R _bfor symbol rate;

2) choose DVB and entirely flow any two PCR in signal, then according to step 1) the code check R of DVB signal that obtains _bcalculate the time difference Δ t of two the PCR arrival selected ₁, simultaneously comprise information according to two PCR selected and calculate the time difference Δ t that two PCR selecting reach ₂, wherein

${\mathrm{\&Delta;t}}_1=\frac{i^{\&prime;}-i^{\&prime;\&prime;}}{R_b}$

${\mathrm{\&Delta;t}}_2=\frac{PCR\left(i^{\&prime;}\right)-PCR\left(i^{\&prime;\&prime;}\right)}{f}$

Wherein, f is the clock frequency of system, f=27MHz.I', i " be call number corresponding to bit byte that described two PCR fields are last.

As Δ t ₁> Δ t ₂time, then this result chosen is: the symbol rate generation negative bias of DVB signal moves; As Δ t ₁< Δ t ₂time, then this result chosen is: the symbol rate of DVB signal occurs just to offset; As Δ t ₁=Δ t ₂, then this result chosen is: the symbol rate of DVB signal offsets;

3) N-1 above-mentioned steps 2 is repeated), when there is the maximum probability that the symbol rate generation negative bias of DVB signal moves in the result to choose for N time, then the symbol rate generation negative bias of DVB signal moves; When occurring that in the result of N statistics the maximum probability just offset occurs the symbol rate of DVB signal, then the symbol rate of DVB signal occurs just to offset; When there is the maximum probability that the symbol rate of DVB signal do not offset in the result of N statistics, then the symbol rate of DVB signal does not offset.

Claims (4)

1. utilize a PCR detected symbol rate offset method in DVB signal, it is characterized in that, comprise the following steps:

1) obtain the symbol rate sending DVB signal, then calculate the code check R of DVB signal according to the symbol rate of DVB signal _b;

2) choose DVB and entirely flow any two PCR in signal, then according to step 1) the code check R of DVB signal that obtains _bcalculate the time difference Δ t that two PCR arrive ₁, the information simultaneously comprised according to two PCR selected calculates the time difference Δ t of two the PCR arrival selected ₂;

As Δ t ₁> Δ t ₂time, then this result chosen is: the symbol rate generation negative bias of DVB signal moves; As Δ t ₁< Δ t ₂time, then this result chosen is: the symbol rate of DVB signal occurs just to offset; As Δ t ₁=Δ t ₂, then this result chosen is: the symbol rate of DVB signal offsets;

3) N-1 above-mentioned steps 2 is repeated), when there is the maximum probability that the symbol rate generation negative bias of DVB signal moves in the result to choose for N time, then the symbol rate generation negative bias of DVB signal moves; When occurring that in the result of N statistics the maximum probability just offset occurs the symbol rate of DVB signal, then the symbol rate of DVB signal occurs just to offset; When there is the maximum probability that the symbol rate of DVB signal do not offset in the result of N statistics, then the symbol rate of DVB signal does not offset.

2. according to claim 1ly utilize PCR detected symbol rate offset method in DVB signal, it is characterized in that, what obtain DVB signal according to the symbol rate of DVB signal goes out code check R _b, wherein,

R _b＝R _B*M*N

Wherein, M is the amount of information that any one symbol carries, and N is code efficiency, R _bfor symbol rate.

3. according to claim 1ly utilize PCR detected symbol rate offset method in DVB signal, it is characterized in that,

${\mathrm{\&Delta;t}}_1=\frac{i^{\&prime;}-i^{\&prime;\&prime;}}{R_b}$

${\mathrm{\&Delta;t}}_2=\frac{PCR\left(i^{\&prime;}\right)-PCR\left(i^{\&prime;\&prime;}\right)}{f}$

Wherein f is the clock frequency of system, i', i " be call number corresponding to bit byte that described two PCR fields are last.

4. according to claim 3ly utilize PCR detected symbol rate offset method in DVB signal, it is characterized in that, f=27MHz.