CN114172565B - Channel quality detection method and system - Google Patents
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Abstract
The invention provides a channel quality detection method and a system, comprising the following steps: step S1: the transmitting terminal transmits a preset periodic pseudo-random code sequence; step S2: integrating the same pseudo-random code generator at the receiving end to generate pseudo-random codes with the same sequence; step S3: the signal received by the receiving end comprises a transmission signal and a reflection signal, and signal sampling is carried out; step S4: the receiving end calculates the correlation between the sampling signal and the pseudo-random code of the same sequence, and determines the time delay and the energy of the signal discontinuous point or the reflection point relative to the main signal; step S5: and calculating the physical distance of the discontinuous point or the reflection point of the signal and the influence on the signal according to the time delay and the energy of the main signal.
Description
Technical Field
The present invention relates to the field of optoelectronic technologies, and in particular, to a method and a system for detecting channel quality, and more particularly, to an optoelectronic device and a method for measuring channel.
Background
As shown in fig. 1, a transmitting end a transmits a signal to a receiving end B, and the intermediate channel has a plurality of discontinuities 1,2, N, during signal transmission, reflection occurs when the signal encounters a discontinuity, and a reflected signal reflects a second or more times at other discontinuities (as shown, the signal reflects a first time at discontinuity 2, the reflected signals collide with the discontinuous point 1 to generate second reflection, then the discontinuous point N generates third reflection, and finally the discontinuous point N-1 generates fourth reflection, as shown in fig. 2, finally each reflected signal is overlapped with the received signal at the receiving end B, so that the quality of the received signal is affected, and error codes are caused.
The quality of the channel is typically measured by a proprietary TDR or OTDR device and requires detection of a normal communication line disconnection. When the TDR/OTDR test is carried out, special equipment is required to replace a transmitting end A to transmit a specific signal, and a channel discontinuous point is detected according to the intensity and the delay of a reflected signal.
Patent document CN113091795a (application number: 202110335135.3) discloses a method, a system, a device and a medium for measuring an optoelectronic device and a channel, including: step S1: configuring a periodic excitation source to transmit a periodic excitation signal A; step S2: collecting an output signal A+NA at an output point of the periodic excitation signal A by using sampling equipment AA, averaging a plurality of periods, and filtering noise; step S3: the acquired output signal A+NA is used as input to a device to be tested or a channel H; step S4: collecting an output signal B+NB at an output point of a device to be tested or a channel H by using sampling equipment BB, calculating an average value of a plurality of periods, and filtering noise; step S5: and transmitting the sampling results of the sampling device AA and the sampling device BB to analysis software C, and calculating the transfer function of the device to be tested or the channel H.
The invention integrates a signal processing algorithm in the equipment of the transmitting end A and the receiving end B, provides a method for detecting the channel quality on line, and locates the position and the reflection intensity of the discontinuous point.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a channel quality detection method and a system.
The channel quality detection method provided by the invention comprises the following steps:
step S1: a preset periodic pseudo-random code sequence is sent at a transmitting end;
step S2: integrating the same pseudo-random code generator at the receiving end to generate pseudo-random codes with the same sequence;
step S3: signal sampling is carried out at a receiving end, and the received sampling signals comprise transmission signals and reflection signals;
step S4: performing correlation calculation on the sampling signal and the pseudo-random code of the same sequence at a receiving end, and determining the time delay and the energy of a signal discontinuous point or a reflection point relative to a main signal;
step S5: and calculating the physical distance of the discontinuous point or the reflection point of the signal and the influence on the signal according to the time delay and the energy of the main signal.
Preferably, the period length of the pseudo-random code sequence is greater than a preset multiple of the single pass transmission time of the signal on the channel.
Preferably, the step S3 employs:
d (t) is a pseudo-random sequence signal of a transmitting end; h (t) is the impulse response of the transmission channel; the signal after reaching the receiving end is D (t) H (t), wherein, the signal is convolution operation;
because of the reflective superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be H r (t) the superimposed signal due to signal discontinuities or reflections is D (t) H r (t), wherein x is a convolution operation;
signal r=d (t) H (t) +d (t) H at the receiving end r (t)＝D(t)*(H(t)+H r (t))＝D(t)*H c (t) wherein H c (t) is a superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sum t (x(t)h(k-t)),k＝-m,...0,1,...n；
wherein R (k) is signal sampling of a receiving end, and k is each sampling time point; x (t) represents a signal x with a delay of 0, h (k-t) represents a channel impulse response h (t) mirrored in time after a delay of k, m represents the influence of m times before the main signal needs to be analyzed, n represents the influence of n times after the main signal needs to be analyzed, sum t Representing the addition of the product of x (t) h (k-t) at all values of t.
Preferably, the step S4 employs: the sampled signal and the same sequence pseudo random code generated by the receiving end are subjected to correlation operation or the sampled signal is stored first, then the sampled signal is read out from a storage unit, and the off-line and same sequence pseudo random codes are subjected to correlation operation.
Preferably, the step S4 employs: in order to reduce the influence of random noise on a calculation result, the received signal is averaged in a plurality of pseudo-random sequence periods M, so that the component of the random noise in a final result is reduced;
the sampling signal R (k) and the same pseudo-random sequence D r (t) performing a correlation calculation:
Correlation(D r ,R(k))/M＝H(t)+H r (t), when D r And D, synchronizing the sequence period of the D;
Correlation(D r r (k))/m=1/M or 0, when D r The sequence periods of (t) and D (t) are not synchronized;
wherein M represents the sequence code pattern period length; the Correlation (Dr, R) represents that the sampled signal and the pseudo random code of the same sequence generated by the receiving end are subjected to Correlation operation;
change D r The starting time position j of the sequence period of (t) and the sampled received signal R (k) are correlated, and the pseudo-random sequence D is calculated for each different starting position r (t-j) performing a correlation operation with the sampled signal to obtain a channel impulse response for each sampling time point j, wherein the impulse response comprises a delay and an energy magnitude of each reflection after the main received signal;
correlation(D r (t-j),R(k))/M＝H c (j)＝H(j)+H r (j),j＝-m,...0,1,...n。
preferably, the step S5 employs: if the impulse sequence D of the pseudo-random sequence is correlated with the received sampled signal ri ，D ri Only one sampling time point in each pseudo-random code bit period represents a pseudo-random code, and when the M value reaches a preset value by utilizing the correlation characteristic of a pseudo-random sequence, 1/M is ignored, so that the channel impulse response of each sampling time point j is obtained:
correlation(D ri (t-j),R(k))/M＝H cp (j)＝H p (j)+H rp (j),j＝-m,...0,1,...n；
wherein H is cp (j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually located at a distance from the transmitting end, H rp (j) Leave H p (j) Has a certain delay of the main signal energy, H cp (j) The energy of the medium-distance main signal reaching the preset value is caused by signal discontinuous points or reflection; by analysis of H cp (j) The amplitude of each reflected energy in (a) and the time from the main signal energy result in the location of the signal discontinuity or reflection point and the reflected energy.
According to the present invention, there is provided a channel quality detection system comprising:
module M1: a preset periodic pseudo-random code sequence is sent at a transmitting end;
module M2: integrating the same pseudo-random code generator at the receiving end to generate pseudo-random codes with the same sequence;
module M3: signal sampling is carried out at a receiving end, and the received sampling signals comprise transmission signals and reflection signals;
module M4: performing correlation calculation on the sampling signal and the pseudo-random code of the same sequence at a receiving end, and determining the time delay and the energy of a signal discontinuous point or a reflection point relative to a main signal;
module M5: and calculating the physical distance of the discontinuous point or the reflection point of the signal and the influence on the signal according to the time delay and the energy of the main signal.
Preferably, the period length of the pseudo-random code sequence is greater than a preset multiple of the single pass transmission time of the signal on the channel.
Preferably, the module M3 employs:
d (t) is a pseudo-random sequence signal of a transmitting end; h (t) is the impulse response of the transmission channel; the signal after reaching the receiving end is D (t) H (t), wherein, the signal is convolution operation;
because of the reflective superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be H r (t) the superimposed signal due to signal discontinuities or reflections is D (t) H r (t), wherein x is a convolution operation;
signal r=d (t) H (t) +d (t) H at the receiving end r (t)＝D(t)*(H(t)+H r (t))＝D(t)*H c (t) wherein H c (t) is a superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sum t (x(t)h(k-t)),k＝-m,...0,1,...n；
wherein R (k) is signal sampling of a receiving end, and k is each sampling time point; x (t) represents a signal x with a delay of 0, h (k-t) represents a channel impulse response h (t) mirrored in time after a delay of k, m represents the influence of m times before the main signal needs to be analyzed, n represents the influence of n times after the main signal needs to be analyzed, sum t Representing the addition of the product of x (t) h (k-t) at all values of t.
Preferably, the module M4 employs: carrying out correlation operation on the sampled signal and the same sequence pseudo random code generated by the receiving end or storing the sampled signal firstly, then reading the sampled signal from a storage unit, and carrying out correlation operation on the off-line pseudo random code and the same sequence pseudo random code;
the module M4 employs: in order to reduce the influence of random noise on a calculation result, the received signal is averaged in a plurality of pseudo-random sequence periods M, so that the component of the random noise in a final result is reduced;
the sampling signal R (k) and the same pseudo-random sequence D r (t) performing a correlation calculation:
Correlation(D r ,R(k))/M＝H(t)+H r (t), when D r And D, synchronizing the sequence period of the D;
Correlation(D r r (k))/m=1/M or 0, when D r The sequence periods of (t) and D (t) are not synchronized;
wherein M represents the sequence code pattern period length; the Correlation (Dr, R) represents that the sampled signal and the pseudo random code of the same sequence generated by the receiving end are subjected to Correlation operation;
change D r The starting time position j of the sequence period of (t) and the sampled received signal R (k) are correlated, and the pseudo-random sequence D is calculated for each different starting position r (t-j) performing a correlation operation with the sampled signal to obtain a channel impulse response for each sampling time point j, wherein the impulse response comprises a delay and an energy magnitude of each reflection after the main received signal;
correlation(D r (t-j),R(k))/M＝H c (j)＝H(j)+H r (j),j＝-m,...0,1,...n；
the module M5 employs: if the impulse sequence D of the pseudo-random sequence is correlated with the received sampled signal ri ，D ri Only one sampling time point in each pseudo-random code bit period represents a pseudo-random code, and when the M value reaches a preset value by utilizing the correlation characteristic of a pseudo-random sequence, 1/M is ignored, so that the channel impulse response of each sampling time point j is obtained:
correlation(D ri (t-j),R(k))/M＝H cp (j)＝H p (j)+H rp (j),j＝-m,...0,1,...n；
wherein H is cp (j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually located at a distance from the transmitting end, H rp (j) Leave H p (j) Has a certain delay of the main signal energy, H cp (j) The energy of the medium-distance main signal reaching the preset value is caused by signal discontinuous points or reflection; by analysis of H cp (j) The amplitude of each reflected energy in (a) and the time from the main signal energy result in the location of the signal discontinuity or reflection point and the reflected energy.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention provides a convenient and quick fault detection method for communication and data networks, generally has the generation function of pseudo-random code sequences in network equipment or chips, can rapidly locate fault points in the network by adding a data sampling function to a receiving end and processing and calculating correlation signals, realizes the technical effect of detecting faults by special TDR equipment, has quick detection time, can be remotely operated on line, reduces the cost of network operation and maintenance, and improves the operation and maintenance efficiency.
The invention solves the problem of on-line detection of channel quality by adding the pseudo-random sequence generator at the transmitting end, sampling the signal at the receiving end and carrying out correlation calculation with the same pseudo-random sequence, and can detect the position and reflection energy of each discontinuous point in the channel.
The reflection intensity and the position of the discontinuous point in the channel can be conveniently obtained, special equipment is not needed, and the detection is performed on line, so that the method can be applied to the channel for transmitting the electric signal, and can also be used for detecting the quality of the optical signal or other channel matching channel influencing the quality of the signal.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
FIG. 1 is a diagram of reflection caused by a discontinuity in a data transmission network channel
Fig. 2 shows the receiving end signal: superposition of transmitted signal and multiple reflected signals
Fig. 3 is a channel quality detection architecture: transmitting terminal, receiving terminal
Fig. 4 shows a receiver signal analysis: superimposed scene of a transmission signal and a reflection signal
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present invention.
Example 1
The channel quality detection method provided by the invention comprises the following steps:
step S1: a preset periodic pseudo-random code sequence is sent at a transmitting end;
step S2: integrating the same pseudo-random code generator at the receiving end to generate pseudo-random codes with the same sequence;
step S3: signal sampling is carried out at a receiving end, and the received sampling signals comprise transmission signals and signal discontinuous points or reflection signals;
step S4: performing correlation calculation on the sampling signal and the pseudo-random code of the same sequence at a receiving end, and determining the time delay and the energy of a signal discontinuous point or a reflection point relative to a main signal;
step S5: and calculating the physical distance of the discontinuous point or the reflection point of the signal and the influence on the signal according to the time delay and the energy of the main signal.
Specifically, the period length of the pseudo-random code sequence is greater than a preset multiple of the single-pass transmission time of the signal in the channel.
Specifically, the step S3 employs:
d (t) is a pseudo-random sequence signal of a transmitting end; h (t) is the impulse response of the transmission channel; the signal after reaching the receiving end is D (t) H (t), wherein, the signal is convolution operation;
because of the reflective superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be H r (t) the superimposed signal due to reflection is D (t) H r (t), wherein x is a convolution operation;
signal r=d (t) H (t) +d (t) H at the receiving end r (t)＝D(t)*(H(t)+H r (t))＝D(t)*H c (t) wherein H c (t) is a superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sum t (x(t)h(k-t)),k＝-m,...0,1,...n；
wherein R (k) is signal sampling of a receiving end, and k is each sampling time point; x (t) represents a signal x with a delay of 0, h (k-t) represents a channel impulse response h (t) mirrored in time after a delay of k, m represents the influence of m times before the main signal needs to be analyzed, n represents the influence of n times after the main signal needs to be analyzed, sum t Representing the addition of the product of x (t) h (k-t) at all values of t.
Specifically, the step S4 employs: the sampled signal and the same sequence pseudo random code generated by the receiving end are subjected to correlation operation or the sampled signal is stored first, then the sampled signal is read out from a storage unit, and the off-line and same sequence pseudo random codes are subjected to correlation operation.
Specifically, the step S4 employs: in order to reduce the influence of random noise on a calculation result, the received signal is averaged in a plurality of pseudo-random sequence periods M, so that the component of the random noise in a final result is reduced;
the sampling signal R (k) and the same pseudo-random sequence D r (t) performing a correlation calculation:
Correlation(D r ,R(k))/M＝H(t)+H r (t), when D r And D, synchronizing the sequence period of the D;
Correlation(D r r (k))/m=1/M or 0, when D r The sequence periods of (t) and D (t) are not synchronized;
wherein M represents the sequence code pattern period length; the Correlation (Dr, R) represents that the sampled signal and the pseudo random code of the same sequence generated by the receiving end are subjected to Correlation operation;
change D r The starting time position j of the sequence period of (t) and the sampled received signal R (k) are correlated, and the pseudo-random sequence D is calculated for each different starting position r (t-j) performing a correlation operation with the sampled signal to obtain a channel impulse response for each sampling time point j, wherein the impulse response comprises a delay and an energy magnitude of each reflection after the main received signal;
correlation(D r (t-j),R(k))/M＝H c (j)＝H(j)+H r (j),j＝-m,...0,1,...n。
specifically, the step S5 employs: if the impulse sequence D of the pseudo-random sequence is correlated with the received sampled signal ri ，D ri Only one sampling time point in each pseudo-random code bit period represents a pseudo-random code, and when the M value reaches a preset value by utilizing the correlation characteristic of a pseudo-random sequence, 1/M is ignored, so that the channel impulse response of each sampling time point j is obtained:
correlation(D ri (t-j),R(k))/M＝H cp (j)＝H p (j)+H rp (j),j＝-m,...0,1,...n；
wherein H is cp (j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually located at a distance from the transmitting end, H rp (j) Leave H p (j) Has a certain delay of the main signal energy, H cp (j) The energy of the medium-distance main signal reaching the preset value is caused by signal discontinuous points or reflection; by analysis of H cp (j) The amplitude of the signal discontinuities or reflected energy and the time from the main signal energy result in the location of the signal discontinuities or reflected points and the reflected energy.
According to the present invention, there is provided a channel quality detection system comprising:
module M1: a preset periodic pseudo-random code sequence is sent at a transmitting end;
module M2: integrating the same pseudo-random code generator at the receiving end to generate pseudo-random codes with the same sequence;
module M3: signal sampling is carried out at a receiving end, and the received sampling signals comprise transmission signals and signal discontinuous points or reflection signals;
module M4: performing correlation calculation on the sampling signal and the pseudo-random code of the same sequence at a receiving end, and determining the time delay and the energy of a signal discontinuous point or a reflection point relative to a main signal;
module M5: and calculating the physical distance of the discontinuous point or the reflection point of the signal and the influence on the signal according to the time delay and the energy of the main signal.
Specifically, the period length of the pseudo-random code sequence is greater than a preset multiple of the single-pass transmission time of the signal in the channel.
Specifically, the module M3 employs:
d (t) is a pseudo-random sequence signal of a transmitting end; h (t) is the impulse response of the transmission channel; the signal after reaching the receiving end is D (t) H (t), wherein, the signal is convolution operation;
because of the reflective superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be H r (t) the superimposed signal due to reflection is D (t) H r (t), wherein x is a convolution operation;
signal r=d (t) H (t) +d (t) H at the receiving end r (t)＝D(t)*(H(t)+H r (t))＝D(t)*H c (t) wherein H c (t) is a superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sum t (x(t)h(k-t)),k＝-m,...0,1,...n；
wherein R (k) is signal sampling of a receiving end, and k is each sampling time point; x (t) represents a signal x with a delay of 0, h (k-t) represents a channel impulse response h (t) mirrored in time after a delay of k, m represents the influence of m times before the main signal needs to be analyzed, n represents the influence of n times after the main signal needs to be analyzed, sum t Representing the addition of the product of x (t) h (k-t) at all values of t.
Specifically, the module M4 employs: carrying out correlation operation on the sampled signal and the same sequence pseudo random code generated by the receiving end or storing the sampled signal firstly, then reading the sampled signal from a storage unit, and carrying out correlation operation on the off-line pseudo random code and the same sequence pseudo random code;
the module M4 employs: in order to reduce the influence of random noise on a calculation result, the received signal is averaged in a plurality of pseudo-random sequence periods M, so that the component of the random noise in a final result is reduced;
the sampling signal R (k) and the same pseudo-random sequence D r (t) performing a correlation calculation:
Correlation(D r ,R(k))/M＝H(t)+H r (t), when D r And D, synchronizing the sequence period of the D;
Correlation(D r r (k))/m=1/M or 0, when D r The sequence periods of (t) and D (t) are not synchronized;
wherein M represents the sequence code pattern period length; the Correlation (Dr, R) represents that the sampled signal and the pseudo random code of the same sequence generated by the receiving end are subjected to Correlation operation;
change D r The starting time position j of the sequence period of (t) and the sampled received signal R (k) are correlated, and the pseudo-random sequence D is calculated for each different starting position r (t-j) performing a correlation operation with the sampled signal to obtain a channel impulse response for each sampling time point j, wherein the impulse response comprises a delay and an energy magnitude of each reflection after the main received signal;
correlation(D r (t-j),R(k))/M＝H c (j)＝H(j)+H r (j),j＝-m,...0,1,...n；
the module M5 employs: if the impulse sequence D of the pseudo-random sequence is correlated with the received sampled signal ri ，D ri Only one sampling time point in each pseudo-random code bit period represents a pseudo-random code, and when the M value reaches a preset value by utilizing the correlation characteristic of a pseudo-random sequence, 1/M is ignored, so that the channel impulse response of each sampling time point j is obtained:
correlation(D ri (t-j),R(k))/M＝H cp (j)＝H p (j)+H rp (j),j＝-m,...0,1,...n；
wherein H is cp (j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually located at a distance from the transmitting end, H rp (j) Leave H p (j) Has a certain delay of the main signal energy, H cp (j) The energy of the medium-distance main signal reaching the preset value is caused by signal discontinuous points or reflection; by analysis of H cp (j) The amplitude of the signal discontinuities or reflected energy and the time from the main signal energy result in the location of the signal discontinuities or reflected points and the reflected energy.
Example 2
Example 2 is a preferred example of example 1
As shown in fig. 3 to 4, the present invention integrates a signal processing algorithm in the devices of the transmitting end a and the receiving end B, provides a method for online detection of channel quality, and locates the location of the discontinuity and the reflection intensity.
The invention relates to a method for transmitting periodic pseudo-random code sequences in a channel, which utilizes the correlation characteristics of pseudo-random codes to carry out correlation operation at a receiving end, deduces a channel transfer function, determines the time delay and the energy of a reflection point relative to a main signal, and calculates the physical distance of the signal discontinuity point or the reflection point and the size affecting the signal.
The channel quality detection method provided by the invention comprises the following steps:
step S1: the transmitting end transmits a preset periodic pseudo-random code sequence, so that the aliasing effect of correlation calculation is avoided, the positioning is convenient, and the period length of the pseudo-random code sequence is more than 2 times of the single-pass transmission time of a signal in a channel; if the aliasing effect exists, the receiving end is required to arrange and combine a plurality of possible reflection positions of each reflection point, and the most possible reflection point position combination is determined by comparing the possible reflection positions with the result after the correlation calculation;
step S2: the receiving end samples the received signal;
step S3: the receiving end calculates the correlation between the sampling signal and the known periodic pseudo-random code sequence the same as the transmitting end, changes the delay t of the known periodic pseudo-random code sequence, and repeats the correlation calculation correlation (t);
step S4: analyzing correlation (t), if the channel is continuous and there is no reflected signal caused by a discontinuous point, the energy of correlation (t) is close to 0 after the main signal, if at t=t0, there is a larger energy in correlation (t=t0), which means that there is a reflected point to cause the reflected signal to arrive at the receiving end after the main signal t0 is delayed, and the round trip distance of signal transmission (in optical fiber transmission, the signal propagates at the speed of light) can be calculated by multiplying the signal transmission speed by t0, so as to determine the position of the reflected point (fault point) leaving the transmitting end. The greater the intensity of the reflection, the greater the energy superimposed on the normal signal, and the effect of each reflection point (fault point) on the signal transmission can be known according to the magnitude of the reflection intensity, and it is determined whether the fault point needs to be repaired.
As shown in fig. 2, the transmitting end integrates a periodic pseudo-random code generator that satisfies the following characteristics:
ABS (Correlation (D (t-i), D (t-j))) =m, when i=j
ABS (Correlation (D (t-i), D (t-j))=1or 0, when i+.j
Wherein D (t-i) and D (t-j) are respectively the same pseudo-random code sequence delayed by a time i and a time j, respectively, M is the sequence pattern period length, for PRBS 2 7 -1 code, m=127, whose autocorrelation function (i+.j) approaches 0 as M increases.
For sampled signals, correlation operations of A (t) and B (t)
correlation(A(t),B(t))＝sum(A(t i )x B(t i )),i＝1,2,...N
Wherein A (t i ) And B (t) i ) A (t) is at t i The value of the moment and B (t) at t i A value of the time of day. If A (t) and B (t) are of low correlation, A (t) i ) And B (t) i ) High randomness, the product of which is a random number, all A (t i )x B(t i ) The sum after addition approaches 0. If A(t i ) And B (t) i ) Has high correlation, all A (t i )x B(t i ) The summed sum will have a value other than 0 relative to the uncorrelated case.
The same pseudo-random code generator is integrated at the receiving end to generate pseudo-random code Dr (t) with the same sequence, the signal received by the receiving end comprises a transmission signal and a reflection signal, and the signal sampling is carried out by the receiving end, which comprises the following steps:
carrying out correlation operation on the sampled signal and the pseudo-random code with the same sequence generated by the receiving end; or firstly storing the sampling signal, then reading the sampling signal from a storage unit, and performing correlation calculation on off-line and same-sequence pseudo-random codes;
the correlation calculation is performed by the two implementation modes, and one is special hardware for integrating the correlation calculation in a device or a chip, so that the calculation can be performed in real time. The other is to store the sampled data and then use the general MCU or other general computing module to calculate, the second mode is slow, but no special hardware for integrating the related calculation is needed.
If D (t) is a pseudo-random sequence signal of a transmitting end, H (t) is an impulse response of a transmission channel, and the signal after reaching a receiving end is D (t) H (t), wherein the signal is convolution operation;
because of the reflective superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be H r (t) the superimposed signal due to reflection is D (t) H r (t), wherein x is a convolution operation;
signal r=d (t) H (t) +d (t) H at the receiving end r (t)＝D(t)*(H(t)+H r (t))＝D(t)*H c (t) wherein H c (t) is a superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sum t (x(t)h(k-t)),k＝-m,...0,1,...n；
r (k) is the signal sampling of the receiving end, wherein k is each sampling time point; x (t) represents a signal x with a delay of 0, h (k-t) represents a channel impulse response h (t) mirrored in time after the delay k, m represents the effect of m times before the main signal needs to be analyzedN represents the influence of n moments after the main signal is needed to be analyzed, sum t Representing the addition of the product of x (t) h (k-t) at all values of t.
To reduce the effect of random noise on the computation results, the received signal may be averaged over multiple pseudorandom sequence periods M, thereby reducing the component of random noise in the final result.
The received sampling signal R (k) and the same pseudo-random sequence D r (t) performing a correlation calculation,
Correlation(D r ,R(k))/M＝H(t)+H r (t), when D r And D, synchronizing the sequence period of the D;
Correlation(D r r (k))/m=1/M or 0, when D r The sequence periods of (t) and D (t) are not synchronized;
Correlation(D r r (k)) represents that the sampled signal and the pseudo random code of the same sequence generated by the receiving end are subjected to correlation operation;
change D r Is correlated with the sampled received signal R (k), and a pseudo-random sequence D is generated for each different starting position r And (t-j) and the sampling signal are subjected to correlation operation, so that the channel impulse response of each sampling time point j is obtained, and the physical position of a signal discontinuous point or a reflection point (fault point) is deduced by the delay and the energy of each reflection after the main receiving signal in the impulse response.
correlation(D r (t-j),R(k))/M＝H c (j)＝H(j)+H r (j),j＝-m,...0,1,...n。
If the impulse sequence D of the pseudo-random sequence is correlated with the received sampled signal ri Namely, only one sampling time point in each pseudo-random code bit period represents a pseudo-random code, and when the M value reaches a preset value by utilizing the correlation characteristic of a pseudo-random sequence, 1/M is ignored, so that the channel impulse response of each sampling time point j is obtained;
correlation(D ri (t-j),R(k))/M＝H cp (j)＝H p (j)+H rp (j),j＝-m,...0,1,...n；
wherein H is cp (j) Is the impulse response of the channel. Since the signal discontinuity or reflection point is usually located at a distance from the transmitting end, H rp (j) Leave H p (j) Has a certain delay of the main signal energy, H cp (j) The energy in the middle that is farther from the main signal energy is the result of signal discontinuities or reflections. By analysis of H cp (j) The amplitude of each reflected energy and the time from the main signal energy can be used for calculating the position of the signal discontinuity or the reflection point and the reflected energy.
H due to periodicity of the pseudo-random code sequence cp (j) Is equal to the pseudo-random code period, if the delay of the reflection point is larger than the pseudo-random code period, the reflection point energy will generate aliasing effect, fold to H cp (j) Is within a period of (2). To avoid aliasing effects, the period length of the pseudorandom code sequence may be increased, or the baud rate of the transmitted signal may be reduced (increasing the period per bit).
The method can conveniently obtain the reflection intensity and the position of the discontinuous point in the channel, the bandwidth and the attenuation of the channel, no special equipment is needed, and the method can be used for detecting on line, and can be applied to the channel for transmitting electric signals, and can also be used for detecting the quality of the channel with influence on the quality of the signal due to the matching of optical signals or other channels.
Those skilled in the art will appreciate that the systems, apparatus, and their respective modules provided herein may be implemented entirely by logic programming of method steps such that the systems, apparatus, and their respective modules are implemented as logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc., in addition to the systems, apparatus, and their respective modules being implemented as pure computer readable program code. Therefore, the system, the apparatus, and the respective modules thereof provided by the present invention may be regarded as one hardware component, and the modules included therein for implementing various programs may also be regarded as structures within the hardware component; modules for implementing various functions may also be regarded as being either software programs for implementing the methods or structures within hardware components.
The foregoing describes specific embodiments of the present invention. It is to be understood that the invention is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the invention. The embodiments of the present application and features in the embodiments may be combined with each other arbitrarily without conflict.
Claims (7)
1. A method for detecting channel quality, comprising:
step S1: a preset periodic pseudo-random code sequence is sent at a transmitting end;
step S2: integrating the same pseudo-random code generator at the receiving end to generate pseudo-random codes with the same sequence;
step S3: signal sampling is carried out at a receiving end, and the received sampling signals comprise transmission signals and reflection signals;
step S4: performing correlation calculation on the sampling signal and the pseudo-random code of the same sequence at a receiving end, and determining the time delay and the energy of a signal discontinuous point or a reflection point relative to a main signal;
step S5: calculating the physical distance of the signal discontinuous point or the reflecting point and the influence on the signal according to the time delay and the energy of the signal discontinuous point or the reflecting point relative to the main signal;
the step S4 employs: in order to reduce the influence of random noise on a calculation result, the received signal is averaged in a plurality of pseudo-random sequence periods M, so that the component of the random noise in a final result is reduced;
the sampling signal R (k) and the same pseudo-random sequence D r (t) performing a correlation calculation:
Correlation(D r ,R(k))/M=H(t)+H r (t), when D r The sequence periods of (t) and D (t) are synchronized;
Correlation(D r r (k))/m=1/M or 0, when D r The sequence periods of (t) and D (t) are not synchronized;
wherein M represents the sequence code pattern period length; correlation (D) r R) represents that the sampled signal and the pseudo-random code of the same sequence generated by the receiving end carry out correlation operation; h (t) meterShowing the impulse response of the transmission channel; h r (t) represents the overall impulse response of the discontinuity, and D (t) represents the pseudo-random sequence signal of the transmitting end;
change D r The starting time position j of the sequence period of (t) and the sampled received signal R (k) are correlated, and the pseudo-random sequence D is calculated for each different starting position r (t-j) performing a correlation operation with the sampled signal to obtain a channel impulse response for each sampling time point j, wherein the impulse response comprises a delay and an energy magnitude of each reflection after the main received signal;
correlation(D r (t-j),R(k))/M=H c (j)=H(j)+H r (j),j=-m,...0,1,...n；
the step S5 employs: if the impulse sequence D of the pseudo-random sequence is correlated with the received sampled signal ri ，D ri Only one sampling time point in each pseudo-random code bit period represents a pseudo-random code, and when the M value reaches a preset value by utilizing the correlation characteristic of a pseudo-random sequence, 1/M is ignored, so that the channel impulse response of each sampling time point j is obtained:
correlation(D ri (t-j),R(k))/M=H cp (j)=H p (j)+H rp (j),j=-m,...0,1,...n；
wherein H is cp (j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually located at a distance from the transmitting end, H rp (j) Leave H p (j) Has a certain delay of the main signal energy, H cp (j) The energy of the medium-distance main signal reaching the preset value is caused by signal discontinuous points or reflection; by analysis of H cp (j) The amplitude of the signal discontinuities or reflected energy and the time from the main signal energy result in the location of the signal discontinuities or reflected points and the reflected energy.
2. The method of claim 1, wherein the pseudo-random code sequence has a period length greater than a predetermined multiple of a single pass transmission time of the signal on the channel.
3. The channel quality detection method according to claim 1, wherein the step S3 employs:
d (t) is a pseudo-random sequence signal of a transmitting end; h (t) is the impulse response of the transmission channel; the signal after reaching the receiving end is D (t) H (t), wherein, the signal is convolution operation;
because of the reflective superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be H r (t) the superimposed signal due to signal discontinuities or reflections is D (t) H r (t), wherein x is a convolution operation;
signal r=d (t) H (t) +d (t) H at the receiving end r (t)=D(t)*(H(t)+H r (t))=D(t)*H c (t) wherein H c (t) is a superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)=sum t (x(t)h(k-t)),k=-m,...0,1,...n；
wherein R (k) is signal sampling of a receiving end, and k is each sampling time point; x (t) represents a signal x with a delay of 0, h (k-t) represents a channel impulse response h (t) mirrored in time after a delay of k, m represents the influence of m times before the main signal needs to be analyzed, n represents the influence of n times after the main signal needs to be analyzed, sum t Representing the addition of the product of x (t) h (k-t) at all values of t.
4. The channel quality detection method according to claim 1, wherein the step S4 employs: the sampled signal and the same sequence pseudo random code generated by the receiving end are subjected to correlation operation or the sampled signal is stored first, then the sampled signal is read out from a storage unit, and the off-line and same sequence pseudo random codes are subjected to correlation operation.
5. A channel quality detection system, comprising:
module M1: a preset periodic pseudo-random code sequence is sent at a transmitting end;
module M2: integrating the same pseudo-random code generator at the receiving end to generate pseudo-random codes with the same sequence;
module M3: signal sampling is carried out at a receiving end, and the received sampling signals comprise transmission signals and reflection signals;
module M4: performing correlation calculation on the sampling signal and the pseudo-random code of the same sequence at a receiving end, and determining the time delay and the energy of a signal discontinuous point or a reflection point relative to a main signal;
module M5: calculating the physical distance of the signal discontinuous point or the reflection point and the influence on the signal according to the time delay and the energy of the signal discontinuous point or the reflection point relative to the main signal;
the module M4 employs: carrying out correlation operation on the sampled signal and the same sequence pseudo random code generated by the receiving end or storing the sampled signal firstly, then reading the sampled signal from a storage unit, and carrying out correlation operation on the off-line pseudo random code and the same sequence pseudo random code;
the module M4 employs: in order to reduce the influence of random noise on a calculation result, the received signal is averaged in a plurality of pseudo-random sequence periods M, so that the component of the random noise in a final result is reduced;
the sampling signal R (k) and the same pseudo-random sequence D r (t) performing a correlation calculation:
Correlation(D r ,R(k))/M=H(t)+H r (t), when D r And D (t) are periodically synchronized with the sequence of D (t);
Correlation(D r r (k))/m=1/M or 0, when D r The sequence periods of (t) and D (t) are not synchronized;
wherein M represents the sequence code pattern period length; correlation (D) r R) represents that the sampled signal and the pseudo-random code of the same sequence generated by the receiving end carry out correlation operation; h (t) represents the impulse response of the transmission channel; h r (t) represents the overall impulse response of the discontinuity, and D (t) represents the pseudo-random sequence signal of the transmitting end;
change D r The starting time position j of the sequence period of (t) and the sampled received signal R (k) are correlated, and the pseudo-random sequence D is calculated for each different starting position r (t-j) and the sampled signal are correlated to obtain eachChannel impulse responses at sample time j, including delay and energy magnitude of each reflection after the primary received signal;
correlation(D r (t-j),R(k))/M=H c (j)=H(j)+H r (j),j=-m,...0,1,...n；
the module M5 employs: if the impulse sequence D of the pseudo-random sequence is correlated with the received sampled signal ri ，D ri Only one sampling time point in each pseudo-random code bit period represents a pseudo-random code, and when the M value reaches a preset value by utilizing the correlation characteristic of a pseudo-random sequence, 1/M is ignored, so that the channel impulse response of each sampling time point j is obtained:
correlation(D ri (t-j),R(k))/M=H cp (j)=H p (j)+H rp (j),j=-m,...0,1,...n；
wherein H is cp (j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually located at a distance from the transmitting end, H rp (j) Leave H p (j) Has a certain delay of the main signal energy, H cp (j) The energy of the medium-distance main signal reaching the preset value is caused by signal discontinuous points or reflection; by analysis of H cp (j) The amplitude of the signal discontinuities or reflected energy and the time from the main signal energy result in the location of the signal discontinuities or reflected points and the reflected energy.
6. The channel quality detection system of claim 5 wherein the pseudo-random code sequence has a period length greater than a predetermined multiple of a signal's one-pass transmission time in the channel.
7. The channel quality detection system according to claim 5, wherein the module M3 employs:
d (t) is a pseudo-random sequence signal of a transmitting end; h (t) is the impulse response of the transmission channel; the signal after reaching the receiving end is D (t) H (t), wherein, the signal is convolution operation;
because of the reflective superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be H r (t) the superimposed signal due to signal discontinuities or reflections is D (t) H r (t), wherein x is a convolution operation;
signal r=d (t) H (t) +d (t) H at the receiving end r (t)=D(t)*(H(t)+H r (t))=D(t)*H c (t) wherein H c (t) is a superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)=sum t (x(t)h(k-t)),k=-m,...0,1,...n；
wherein R (k) is signal sampling of a receiving end, and k is each sampling time point; x (t) represents a signal x with a delay of 0, h (k-t) represents a channel impulse response h (t) mirrored in time after a delay of k, m represents the influence of m times before the main signal needs to be analyzed, n represents the influence of n times after the main signal needs to be analyzed, sum t Representing the addition of the product of x (t) h (k-t) at all values of t.
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