CN114172565A - Channel quality detection method and system - Google Patents

Channel quality detection method and system Download PDF

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CN114172565A
CN114172565A CN202111470785.5A CN202111470785A CN114172565A CN 114172565 A CN114172565 A CN 114172565A CN 202111470785 A CN202111470785 A CN 202111470785A CN 114172565 A CN114172565 A CN 114172565A
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CN114172565B (en
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王珲
王炯明
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Shanghai Orange Microelectronics Technology Co ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/071—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using a reflected signal, e.g. using optical time domain reflectometers [OTDR]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
    • H04B10/075—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal
    • H04B10/077—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems using an in-service signal using a supervisory or additional signal
    • H04B10/0771—Fault location on the transmission path
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

The invention provides a channel quality detection method and a system, comprising the following steps: step S1: a transmitting end transmits a preset periodic pseudo-random code sequence; step S2: integrating the same pseudo-random code generator at a 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 carries out correlation calculation on the sampling signal and the pseudo-random code of the same sequence, and determines the time delay and the energy of a signal discontinuous point or a reflection point relative to the main signal; step S5: and calculating the physical distance of the signal discontinuity point or the reflection point and the influence on the signal according to the time delay and the energy of the main signal.

Description

Channel quality detection method and system
Technical Field
The present invention relates to the field of optoelectronics, and in particular, to a method and a system for detecting channel quality, and more particularly, to an optoelectronic device and a channel measurement method.
Background
As shown in fig. 1, a sending end a sends a signal to a receiving end B, an intermediate channel has a plurality of discontinuities 1,2,.. and N, in the process of signal transmission, reflection occurs when a discontinuity is encountered, and a reflected signal generates second or more reflections at other discontinuities (as shown in the figure, a signal is reflected at a discontinuity 2 for the first time, a reflected signal encounters a discontinuity 1 to generate a second reflection, then a discontinuity N generates a third reflection, and finally a discontinuity N-1 generates a fourth reflection).
The quality of the channel is typically measured by proprietary TDR or OTDR equipment and requires the disconnection of a normal communication line for detection. When performing a TDR/OTDR test, a dedicated device needs to replace the transmitting end a, transmit a specific signal, and detect a channel discontinuity point according to the strength and delay of a reflected signal.
Patent document CN113091795A (application No. 202110335135.3) discloses a method, system, apparatus, and medium for measuring photoelectric devices and channels, including: step S1: configuring a periodic excitation source to send 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 a sampling device AA, averaging a plurality of periods, and filtering noise; step S3: the collected output signal A + NA is used as input to be connected to a device to be tested or a channel H; step S4: collecting an output signal B + NB by using sampling equipment BB at an output point of a device to be tested or a channel H, carrying out average value calculation of a plurality of periods, and filtering noise; step S5: and transmitting the sampling results of the sampling equipment AA and the sampling equipment BB to analysis software C, and calculating the transfer function of the device to be tested or the channel H.
The invention integrates signal processing algorithm in the equipment of the sending end A and the receiving end B, provides a method for detecting the channel quality on line, and positions 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 channel quality detection system.
The channel quality detection method provided by the invention comprises the following steps:
step S1: sending a preset periodic pseudo-random code sequence at a transmitting end;
step S2: integrating the same pseudo-random code generator at a receiving end to generate pseudo-random codes with the same sequence;
step S3: carrying out signal sampling at a receiving end, wherein the received sampling signal comprises a transmission signal and a reflection signal;
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 signal discontinuity point or the reflection point 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 larger than a preset time of one-way transmission of the signal in the channel.
Preferably, the step S3 adopts:
d (t) is a pseudo-random sequence signal of a sending end; h (t) is the impulse response of the transmission channel; after reaching the receiving end, the signal is D (t) H (t), wherein the signal is convolution operation;
due to the reflection superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be Hr(t), the superimposed signal due to signal discontinuities or reflections is D (t) Hr(t), wherein x is a convolution operation;
the signal R ═ d (t) × H (t) + d (t) × H at the receiving endr(t)＝D(t)*(H(t)+Hr(t))＝D(t)*Hc(t) wherein Hc(t) is the superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sumt(x(t)h(k-t)),k＝-m,...0,1,...n；
wherein, r (k) is a signal sample of the 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) which is subjected to mirror mapping in time after the delay of time k, m represents the influence of m moments before the main signal to be analyzed, n represents the influence of n moments after the main signal to be analyzed, and sumtMeans that the products of x (t) h (k-t) are summed up for all values of t.
Preferably, the step S4 adopts: the sampled signal and the pseudo random code with the same sequence generated by the receiving end are subjected to correlation operation or the sampled signal is stored firstly, then the sampled signal is read out from the storage unit, and the correlation operation is carried out on the pseudo random code with the same sequence in an off-line manner.
Preferably, the step S4 adopts: in order to reduce the influence of random noise on the calculation result, averaging the received signal in a plurality of pseudo-random sequence periods M, thereby reducing the component of the random noise in the final result;
mixing the sampled signal R (k) with the same pseudo-random sequence Dr(t) performing a correlation calculation:
Correlation(Dr,R(k))/M＝H(t)+Hr(t) when DrAnd D are synchronized with the sequence period;
Correlation(Drr (k)/M1/M or 0, when Dr(t) and the sequence periods of D (t) are not synchronized;
wherein M represents the period length of the sequence code pattern; 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 Dr(t) correlating the start time position j of the sequence period with the sampled received signal R (k), and for each different start position, correlating the pseudo-random sequence Dr(t-j) performing correlation operation on the sampled signals to obtain a channel impulse response of each sampling time point j, wherein the impulse response comprises the delay and the energy of each reflection after the main received signal;
correlation(Dr(t-j),R(k))/M＝Hc(j)＝H(j)+Hr(j),j＝-m,...0,1,...n。
preferably, the step S5 adopts: if the correlation with the received sample signal is a pseudo-random sequence of the impulse sequence Dri，DriOnly one sampling time point in each pseudo random code bit period represents a pseudo random code, and by utilizing the correlation characteristic of the pseudo random sequence, when the value of M reaches a preset value, 1/M is ignored, and then the channel impulse response of each sampling time point j is obtained:
correlation(Dri(t-j),R(k))/M＝Hcp(j)＝Hp(j)+Hrp(j),j＝-m,...0,1,...n；
wherein Hcp(j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually some distance from the transmitting end, Hrp(j) Leave Hp(j) Has a certain delay of the main signal energy, Hcp(j) The energy when the energy of the middle distance main signal reaches a preset value is caused by signal discontinuity points or reflection; by analysis of Hcp(j) The amplitude of each reflected energy and the time from the main signal energy are used to obtain the position of the signal discontinuity point or the reflection point and the reflected energy.
The invention provides a channel quality detection system, comprising:
module M1: sending a preset periodic pseudo-random code sequence at a transmitting end;
module M2: integrating the same pseudo-random code generator at a receiving end to generate pseudo-random codes with the same sequence;
module M3: carrying out signal sampling at a receiving end, wherein the received sampling signal comprises a transmission signal and a reflection signal;
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 signal discontinuity point or the reflection point 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 larger than a preset time of one-way transmission of the signal in the channel.
Preferably, the module M3 employs:
d (t) is a pseudo-random sequence signal of a sending end; h (t) is the impulse response of the transmission channel; after reaching the receiving end, the signal is D (t) H (t), wherein the signal is convolution operation;
due to the reflection superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be Hr(t) due to signal discontinuities or vice versaThe superposed signal resulting from the emission is D (t) Hr(t), wherein x is a convolution operation;
the signal R ═ d (t) × H (t) + d (t) × H at the receiving endr(t)＝D(t)*(H(t)+Hr(t))＝D(t)*Hc(t) wherein Hc(t) is the superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sumt(x(t)h(k-t)),k＝-m,...0,1,...n；
wherein, r (k) is a signal sample of the 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) which is subjected to mirror mapping in time after the delay of time k, m represents the influence of m moments before the main signal to be analyzed, n represents the influence of n moments after the main signal to be analyzed, and sumtMeans that the products of x (t) h (k-t) are summed up for all values of t.
Preferably, the module M4 employs: the sampled signal and the pseudo random code with the same sequence generated by the receiving end are subjected to correlation operation or the sampled signal is stored firstly, then the sampled signal is read out from the storage unit, and the correlation operation is carried out on the pseudo random code with the same sequence in an off-line manner;
the module M4 employs: in order to reduce the influence of random noise on the calculation result, averaging the received signal in a plurality of pseudo-random sequence periods M, thereby reducing the component of the random noise in the final result;
mixing the sampled signal R (k) with the same pseudo-random sequence Dr(t) performing a correlation calculation:
Correlation(Dr,R(k))/M＝H(t)+Hr(t) when DrAnd D are synchronized with the sequence period;
Correlation(Drr (k)/M1/M or 0, when Dr(t) and the sequence periods of D (t) are not synchronized;
wherein M represents the period length of the sequence code pattern; 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 Dr(t) at the start time position j of the sequence period, and sampling the received signal R (k)Correlation calculation, for each different starting position, a pseudo-random sequence Dr(t-j) performing correlation operation on the sampled signals to obtain a channel impulse response of each sampling time point j, wherein the impulse response comprises the delay and the energy of each reflection after the main received signal;
correlation(Dr(t-j),R(k))/M＝Hc(j)＝H(j)+Hr(j),j＝-m,...0,1,...n；
the module M5 employs: if the correlation with the received sample signal is a pseudo-random sequence of the impulse sequence Dri，DriOnly one sampling time point in each pseudo random code bit period represents a pseudo random code, and by utilizing the correlation characteristic of the pseudo random sequence, when the value of M reaches a preset value, 1/M is ignored, and then the channel impulse response of each sampling time point j is obtained:
correlation(Dri(t-j),R(k))/M＝Hcp(j)＝Hp(j)+Hrp(j),j＝-m,...0,1,...n；
wherein Hcp(j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually some distance from the transmitting end, Hrp(j) Leave Hp(j) Has a certain delay of the main signal energy, Hcp(j) The energy when the energy of the middle distance main signal reaches a preset value is caused by signal discontinuity points or reflection; by analysis of Hcp(j) The amplitude of each reflected energy and the time from the main signal energy are used to obtain the position of the signal discontinuity point or the 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 fast fault detection method for communication and data networks, generally has a pseudo-random code sequence generation function in network equipment or a chip, can quickly locate a fault point in the network by only adding a data sampling function at a receiving end and processing and calculating correlation signals, realizes the technical effect of detecting faults by using special TDR equipment, has fast detection time, can remotely operate 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 a pseudo-random sequence generator at a transmitting end, sampling signals at a receiving end and carrying out correlation calculation with the same pseudo-random sequence, and can detect the position and the reflection energy of each discontinuous point in a channel.
The method can conveniently obtain the reflection intensity and the position of a discontinuous point in a channel, does not need special equipment, performs online detection, can be applied to a channel for transmitting electric signals, and can also be used for detecting the quality of the channel with the influence of optical signals or other channel matching on the quality of the signals.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a diagram of reflections caused by discontinuities in data transmission network channels
Fig. 2 shows the receiving end signals: superposition of a transmitted signal and a plurality of reflected signals
Fig. 3 is a channel quality detection architecture: transmitting end, receiving end
Fig. 4 shows the receiving end signal analysis: superimposed scene of transmission signal and 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 invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
Example 1
The channel quality detection method provided by the invention comprises the following steps:
step S1: sending a preset periodic pseudo-random code sequence at a transmitting end;
step S2: integrating the same pseudo-random code generator at a receiving end to generate pseudo-random codes with the same sequence;
step S3: carrying out signal sampling at a receiving end, wherein the received sampling signal comprises a transmission signal and a signal discontinuous point or a reflection signal;
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 signal discontinuity point or the reflection point 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 larger than a preset time of one-way transmission time of a signal in a channel.
Specifically, the step S3 employs:
d (t) is a pseudo-random sequence signal of a sending end; h (t) is the impulse response of the transmission channel; after reaching the receiving end, the signal is D (t) H (t), wherein the signal is convolution operation;
due to the reflection superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be Hr(t), the superimposed signal due to reflection is D (t) Hr(t), wherein x is a convolution operation;
the signal R ═ d (t) × H (t) + d (t) × H at the receiving endr(t)＝D(t)*(H(t)+Hr(t))＝D(t)*Hc(t) wherein Hc(t) is the superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sumt(x(t)h(k-t)),k＝-m,...0,1,...n；
wherein, r (k) is a signal sample of the 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) which is subjected to mirror mapping in time after the delay of time k, m represents the influence of m moments before the main signal to be analyzed, n represents the influence of n moments after the main signal to be analyzed, and sumtMeans that the products of x (t) h (k-t) are summed up for all values of t.
Specifically, the step S4 employs: the sampled signal and the pseudo random code with the same sequence generated by the receiving end are subjected to correlation operation or the sampled signal is stored firstly, then the sampled signal is read out from the storage unit, and the correlation operation is carried out on the pseudo random code with the same sequence in an off-line manner.
Specifically, the step S4 employs: in order to reduce the influence of random noise on the calculation result, averaging the received signal in a plurality of pseudo-random sequence periods M, thereby reducing the component of the random noise in the final result;
mixing the sampled signal R (k) with the same pseudo-random sequence Dr(t) performing a correlation calculation:
Correlation(Dr,R(k))/M＝H(t)+Hr(t) when DrAnd D are synchronized with the sequence period;
Correlation(Drr (k)/M1/M or 0, when Dr(t) and the sequence periods of D (t) are not synchronized;
wherein M represents the period length of the sequence code pattern; 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 Dr(t) correlating the start time position j of the sequence period with the sampled received signal R (k), and for each different start position, correlating the pseudo-random sequence Dr(t-j) performing correlation operation on the sampled signals to obtain a channel impulse response of each sampling time point j, wherein the impulse response comprises the delay and the energy of each reflection after the main received signal;
correlation(Dr(t-j),R(k))/M＝Hc(j)＝H(j)+Hr(j),j＝-m,...0,1,...n。
specifically, the step S5 employs: if the correlation with the received sample signal is a pseudo-random sequence of the impulse sequence Dri，DriOnly one sampling time point in each pseudo random code bit period represents a pseudo random code, and by utilizing the correlation characteristic of the pseudo random sequence, when the value of M reaches a preset value, 1/M is ignored, and then the channel impulse response of each sampling time point j is obtained:
correlation(Dri(t-j),R(k))/M＝Hcp(j)＝Hp(j)+Hrp(j),j＝-m,...0,1,...n；
wherein Hcp(j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually some distance from the transmitting end, Hrp(j) Leave Hp(j) Has a certain delay of the main signal energy, Hcp(j) The energy when the energy of the middle distance main signal reaches a preset value is caused by signal discontinuity points or reflection; by analysis of Hcp(j) And obtaining the position and the reflected energy of the signal discontinuity point or the reflected point by the amplitude of each signal discontinuity point or the reflected energy and the time from the main signal energy.
The invention provides a channel quality detection system, comprising:
module M1: sending a preset periodic pseudo-random code sequence at a transmitting end;
module M2: integrating the same pseudo-random code generator at a receiving end to generate pseudo-random codes with the same sequence;
module M3: carrying out signal sampling at a receiving end, wherein the received sampling signal comprises a transmission signal and a signal discontinuous point or a reflection signal;
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 signal discontinuity point or the reflection point 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 larger than a preset time of one-way transmission time of a signal in a channel.
Specifically, the module M3 employs:
d (t) is a pseudo-random sequence signal of a sending end; h (t) is the impulse response of the transmission channel; after reaching the receiving end, the signal is D (t) H (t), wherein the signal is convolution operation;
due to the reflection superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be Hr(t), the superimposed signal due to reflection is D (t) Hr(t), wherein x is a convolution operation;
the signal R ═ d (t) × H (t) + d (t) × H at the receiving endr(t)＝D(t)*(H(t)+Hr(t))＝D(t)*Hc(t) wherein Hc(t) is the superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sumt(x(t)h(k-t)),k＝-m,...0,1,...n；
wherein, r (k) is a signal sample of the 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) which is subjected to mirror mapping in time after the delay of time k, m represents the influence of m moments before the main signal to be analyzed, n represents the influence of n moments after the main signal to be analyzed, and sumtMeans that the products of x (t) h (k-t) are summed up for all values of t.
Specifically, the module M4 employs: the sampled signal and the pseudo random code with the same sequence generated by the receiving end are subjected to correlation operation or the sampled signal is stored firstly, then the sampled signal is read out from the storage unit, and the correlation operation is carried out on the pseudo random code with the same sequence in an off-line manner;
the module M4 employs: in order to reduce the influence of random noise on the calculation result, averaging the received signal in a plurality of pseudo-random sequence periods M, thereby reducing the component of the random noise in the final result;
mixing the sampled signal R (k) with the same pseudo-random sequence Dr(t) performing a correlation calculation:
Correlation(Dr,R(k))/M＝H(t)+Hr(t) when DrAnd D are synchronized with the sequence period;
Correlation(Drr (k)/M1/M or 0, when Dr(t) and the sequence periods of D (t) are not synchronized;
wherein M represents the period length of the sequence code pattern; 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 Dr(t) performing a correlation calculation with the sampled received signal R (k) at a start time position j of the sequence period, for each different start bitSet pseudo-random sequence Dr(t-j) performing correlation operation on the sampled signals to obtain a channel impulse response of each sampling time point j, wherein the impulse response comprises the delay and the energy of each reflection after the main received signal;
correlation(Dr(t-j),R(k))/M＝Hc(j)＝H(j)+Hr(j),j＝-m,...0,1,...n；
the module M5 employs: if the correlation with the received sample signal is a pseudo-random sequence of the impulse sequence Dri，DriOnly one sampling time point in each pseudo random code bit period represents a pseudo random code, and by utilizing the correlation characteristic of the pseudo random sequence, when the value of M reaches a preset value, 1/M is ignored, and then the channel impulse response of each sampling time point j is obtained:
correlation(Dri(t-j),R(k))/M＝Hcp(j)＝Hp(j)+Hrp(j),j＝-m,...0,1,...n；
wherein Hcp(j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually some distance from the transmitting end, Hrp(j) Leave Hp(j) Has a certain delay of the main signal energy, Hcp(j) The energy when the energy of the middle distance main signal reaches a preset value is caused by signal discontinuity points or reflection; by analysis of Hcp(j) And obtaining the position and the reflected energy of the signal discontinuity point or the reflected point by the amplitude of each signal discontinuity point or the reflected energy and the time from the main signal energy.
Example 2
Example 2 is a preferred example of example 1
As shown in fig. 3 to 4, the present invention integrates signal processing algorithms in the devices of the transmitting end a and the receiving end B, and provides a method for detecting the channel quality online, and locates the position of the discontinuity and the reflection intensity.
The invention is characterized in that a periodic pseudo-random code sequence is transmitted in a channel, correlation operation is carried out at a receiving end by utilizing the correlation characteristic of the pseudo-random code, a channel transmission function is deduced, the time delay and the energy of a reflection point relative to a main signal are determined, and the signal discontinuity point or the physical distance of the reflection point and the influence on the signal are calculated.
The channel quality detection method provided by the invention comprises the following steps:
step S1: a transmitting end transmits a preset periodic pseudo-random code sequence, in order to avoid the aliasing effect of correlation calculation and facilitate positioning, the period length of the pseudo-random code sequence is more than 2 times of the one-way transmission time of a signal in a channel; if aliasing effect exists, the receiving end is required to arrange and combine a plurality of possible reflection positions of each reflection point, and the arranged and combined reflection positions are compared with the result obtained after the correlation calculation to determine the most possible reflection point position combination;
step S2: the receiving end samples the received signal;
step S3: the receiving end makes the correlation calculation to the sampling signal and the known periodic pseudo random code sequence same as the transmitting end, changes the delay t of the known periodic pseudo random code sequence, repeats the correlation calculation (t);
step S4: the correlation (t) is analyzed, if the channel is continuous and there is no reflected signal caused by a discontinuous point, the energy of the correlation (t) is close to 0 after the main signal, if there is a larger energy at t0, the correlation (t 0) indicates that there is a reflection point causing 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, thereby determining the position of the reflection point (fault point) from the transmitting end. The larger the intensity of the reflection is, the larger the energy which is superposed on the normal signal is, and according to the intensity of the reflection, the influence of each reflection point (fault point) on the signal transmission can be known, and whether the fault point needs to be repaired or not can be determined.
As shown in fig. 2, the transmitting end integrates a periodic pseudo-random code generator, which satisfies the following characteristics:
ABS (correction (D (t-i), D (t-j))) (M, when i ═ j)
ABS (Correlation (D (t-i), D (t-j)) -1 or 0 when i ≠ j
Wherein D (t-i) and D (t-j) are respectively the same pseudo random code sequence delayed by time i and time j, M is the period length of the sequence code pattern, for PRBS 27Code-1, M ≠ 127, whose autocorrelation function (i ≠ j) approaches 0 as M increases.
Correlation of A (t) and B (t) for sampled signals
correlation(A(t),B(t))＝sum(A(ti)x B(ti)),i＝1,2,...N
Wherein, A (t)i) And B (t)i) Respectively A (t) at tiThe sum of the values of time and B (t) at tiThe value of the time of day. If A (t) and B (t) have low correlation, A (t)i) And B (t)i) The randomness is high, and the product of the randomness and the randomness is a random number, all A (t)i)x B(ti) The added sum approaches 0. If A (t)i) And B (t)i) High correlation, all A (t)i)x B(ti) The summed sum will have a value other than 0 relative to the uncorrelated case.
Integrating the same pseudo-random code generator at a receiving end to generate pseudo-random codes Dr (t) with the same sequence, wherein the signals received by the receiving end comprise transmission signals and reflection signals, and the receiving end carries out signal sampling and comprises the following steps:
carrying out correlation operation on the sampled signal and a pseudo-random code with the same sequence generated by a receiving end; or the sampling signal is stored firstly, then the sampling signal is read out from the storage unit, and correlation calculation is carried out on the off-line and same-sequence pseudo-random codes;
the correlation calculation is performed through the two implementation modes, and one is to integrate special hardware of the correlation calculation in a device or a chip, so that the calculation can be performed in real time. The other is that the sampled data is stored first and then read out and calculated by a general MCU or other general calculation modules, and the second mode is slow but does not need special hardware for integrating related calculation.
If D (t) is the pseudo-random sequence signal of the sending end, H (t) is the impact response of the transmission channel, the signal is D (t) H (t) after reaching the receiving end, wherein, the signal is convolution operation;
due to the reflection superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be Hr(t), the superimposed signal due to reflection is D (t) Hr(t), wherein x is a convolution operation;
the signal R ═ d (t) × H (t) + d (t) × H at the receiving endr(t)＝D(t)*(H(t)+Hr(t))＝D(t)*Hc(t) in which Hc(t) is the superimposed impulse response of the channel impulse response and the reflection impulse response;
R(k)＝sumt(x(t)h(k-t)),k＝-m,...0,1,...n；
r (k) is a signal sample at the receiving end, where 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) which is subjected to mirror mapping in time after the delay of time k, m represents the influence of m moments before the main signal to be analyzed, n represents the influence of n moments after the main signal to be analyzed, and sumtMeans that the products of x (t) h (k-t) are summed up for all values of t.
In order to reduce the influence of random noise on the calculation result, the received signal may be averaged over a plurality of pseudo-random sequence periods M, thereby reducing the component of random noise in the final result.
Receiving sampling signal R (k) and the same pseudo-random sequence Dr(t) performing a correlation calculation, wherein,
Correlation(Dr,R(k))/M＝H(t)+Hr(t) when DrAnd D are synchronized with the sequence period;
Correlation(Drr (k)/M1/M or 0, when Dr(t) and the sequence periods of D (t) are not synchronized;
Correlation(Drr (k)) represents that the sampled signal and the pseudo random code of the same sequence produced by the receiving end carry on the correlation operation;
change DrAnd the sampled received signal R (k) is correlated with a start time position j of the sequence period of (a), and for each different start position a pseudo-random sequence D is appliedr(t-j) and the sampling signal are subjected to correlation operation, so that the channel impact response of each sampling time point j is obtainedThe delay and the amount of energy of each reflection in the impulse response after the main received signal, thus deducing the physical location of the signal discontinuity or reflection point (fault point).
correlation(Dr(t-j),R(k))/M＝Hc(j)＝H(j)+Hr(j),j＝-m,...0,1,...n。
If the correlation with the received sample signal is a pseudo-random sequence of the impulse sequence DriOnly one sampling time point in each pseudo random code bit period represents a pseudo random code, and by utilizing the correlation characteristic of the pseudo random sequence, when the value M reaches a preset value, 1/M is ignored, and the channel pulse response of each sampling time point j is obtained;
correlation(Dri(t-j),R(k))/M＝Hcp(j)＝Hp(j)+Hrp(j),j＝-m,...0,1,...n；
wherein Hcp(j) Is the impulse response of the channel. Since the signal discontinuity or reflection point is usually some distance from the transmitting end, Hrp(j) Leave Hp(j) Has a certain delay of the main signal energy, Hcp(j) The energy more distant from the main signal energy is caused by signal discontinuities or reflections. By analysis of Hcp(j) The amplitude of each reflected energy and the time from the main signal energy can be used to calculate the position of the signal discontinuity point or the reflection point and the reflected energy.
Due to the periodicity of the pseudo-random code sequence, Hcp(j) Is equal to the pseudo-random code period, if the delay of the reflection point is greater than the pseudo-random code period, the energy of the reflection point will produce an aliasing effect, folding to Hcp(j) Within the period of (c). To avoid aliasing effects, the period length of the pseudo-random code sequence can be increased, or the baud rate of the transmitted signal can be decreased (increasing the period of each bit).
By the method, the reflection intensity and the position of a discontinuous point in a channel, the bandwidth and the attenuation of the channel can be conveniently obtained, special equipment is not needed, the online detection is carried out, and the method can be applied to the channel for transmitting electric signals and the channel quality detection that optical signals or other channel matches and affects the signal quality.
Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and various modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps such that the systems, apparatus, and various modules thereof are provided in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the device and the modules thereof provided by the present invention can be considered as a hardware component, and the modules included in the system, the device and the modules thereof for implementing various programs can also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims (10)

1. A method for channel quality detection, comprising:
step S1: sending a preset periodic pseudo-random code sequence at a transmitting end;
step S2: integrating the same pseudo-random code generator at a receiving end to generate pseudo-random codes with the same sequence;
step S3: carrying out signal sampling at a receiving end, wherein the received sampling signal comprises a transmission signal and a reflection signal;
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 signal discontinuity point or the reflection point and the influence on the signal according to the time delay and the energy of the main signal.
2. The method of claim 1, wherein the period length of the pseudo-random code sequence is greater than a preset multiple of a single-pass transmission time of a signal in the channel.
3. The channel quality detecting method according to claim 1, wherein the step S3 employs:
d (t) is a pseudo-random sequence signal of a sending end; h (t) is the impulse response of the transmission channel; after reaching the receiving end, the signal is D (t) H (t), wherein the signal is convolution operation;
due to the reflection superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be Hr(t), the superimposed signal due to signal discontinuities or reflections is D (t) Hr(t), wherein x is a convolution operation;
the signal R ═ d (t) × H (t) + d (t) × H at the receiving endr(t)＝D(t)*(H(t)+Hr(t))＝D(t)*Hc(t) wherein Hc(t) is the superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sumt(x(t)h(k-t)),k＝-m,...0,1,...n；
wherein, r (k) is a signal sample of the 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) which is subjected to mirror mapping in time after the delay of time k, m represents the influence of m moments before the main signal to be analyzed, n represents the influence of n moments after the main signal to be analyzed, and sumtMeans that the products of x (t) h (k-t) are summed up for all values of t.
4. The channel quality detecting method according to claim 1, wherein the step S4 employs: the sampled signal and the pseudo random code with the same sequence generated by the receiving end are subjected to correlation operation or the sampled signal is stored firstly, then the sampled signal is read out from the storage unit, and the correlation operation is carried out on the pseudo random code with the same sequence in an off-line manner.
5. The channel quality detecting method according to claim 1, wherein the step S4 employs: in order to reduce the influence of random noise on the calculation result, averaging the received signal in a plurality of pseudo-random sequence periods M, thereby reducing the component of the random noise in the final result;
mixing the sampled signal R (k) with the same pseudo-random sequence Dr(t) performing a correlation calculation:
Correlation(Dr,R(k))/M＝H(t)+Hr(t) when DrAnd D are synchronized with the sequence period;
Correlation(Drr (k)/M1/M or 0, when Dr(t) and the sequence periods of D (t) are not synchronized;
wherein M represents the period length of the sequence code pattern; 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 Dr(t) correlating the start time position j of the sequence period with the sampled received signal R (k), and for each different start position, correlating the pseudo-random sequence Dr(t-j) performing correlation operation on the sampled signals to obtain a channel impulse response of each sampling time point j, wherein the impulse response comprises the delay and the energy of each reflection after the main received signal;
correlation(Dr(t-j),R(k))/M＝Hc(j)＝H(j)+Hr(j),j＝-m,...0,1,...n。
6. the channel quality detecting method according to claim 5, wherein the step S5 adopts: if the correlation with the received sample signal is a pseudo-random sequence of the impulse sequence Dri，DriOnly one sampling time point in each pseudo random code bit period represents a pseudo random code, and by utilizing the correlation characteristic of the pseudo random sequence, when the value of M reaches a preset value, 1/M is ignored, and then the channel impulse response of each sampling time point j is obtained:
correlation(Dri(t-j),R(k))/M＝Hcp(j)＝Hp(j)+Hrp(j),j＝-m,...0,1,...n；
wherein Hcp(j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually some distance from the transmitting end, Hrp(j) Leave Hp(j) Has a certain delay of the main signal energy, Hcp(j) The energy when the energy of the middle distance main signal reaches a preset value is caused by signal discontinuity points or reflection; by analysis of Hcp(j) And obtaining the position and the reflected energy of the signal discontinuity point or the reflected point by the amplitude of each signal discontinuity point or the reflected energy and the time from the main signal energy.
7. A channel quality detection system, comprising:
module M1: sending a preset periodic pseudo-random code sequence at a transmitting end;
module M2: integrating the same pseudo-random code generator at a receiving end to generate pseudo-random codes with the same sequence;
module M3: carrying out signal sampling at a receiving end, wherein the received sampling signal comprises a transmission signal and a reflection signal;
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 signal discontinuity point or the anti-point and the influence on the signal according to the time delay and the energy of the main signal.
8. The channel quality detection system of claim 7, wherein the pseudo-random code sequence has a period length greater than a preset multiple of a one-way transmission time of a signal on the channel.
9. The channel quality detection system according to claim 7, wherein the module M3 employs:
d (t) is a pseudo-random sequence signal of a sending end; h (t) is the impulse response of the transmission channel; after reaching the receiving end, the signal is D (t) H (t), wherein the signal is convolution operation;
due to the reflection superposition of the discontinuities, the overall impact response of the discontinuities is assumed to be Hr(t), the superimposed signal due to signal discontinuities or reflections is D (t) Hr(t), wherein x is a convolution operation;
the signal R ═ d (t) × H (t) + d (t) × H at the receiving endr(t)＝D(t)*(H(t)+Hr(t))＝D(t)*Hc(t) wherein Hc(t) is the superimposed impulse response of the channel impulse response and the reflected impulse response;
R(k)＝sumt(x(t)h(k-t)),k＝-m,...0,1,...n；
wherein, r (k) is a signal sample of the 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) which is subjected to mirror mapping in time after the delay of time k, m represents the influence of m moments before the main signal to be analyzed, n represents the influence of n moments after the main signal to be analyzed, and sumtMeans that the products of x (t) h (k-t) are summed up for all values of t.
10. The channel quality detection system according to claim 7, wherein the module M4 employs: the sampled signal and the pseudo random code with the same sequence generated by the receiving end are subjected to correlation operation or the sampled signal is stored firstly, then the sampled signal is read out from the storage unit, and the correlation operation is carried out on the pseudo random code with the same sequence in an off-line manner;
the module M4 employs: in order to reduce the influence of random noise on the calculation result, averaging the received signal in a plurality of pseudo-random sequence periods M, thereby reducing the component of the random noise in the final result;
mixing the sampled signal R (k) with the same pseudo-random sequence Dr(t) performing a correlation calculation:
Correlation(Dr,R(k))/M＝H(t)+Hr(t) when DrAnd D are synchronized with the sequence period;
Correlation(Drr (k)/M1/M or 0, when Dr(t) and the sequence periods of D (t) are not synchronized;
wherein M represents the period length of the sequence code pattern; 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 Dr(t) correlating the start time position j of the sequence period with the sampled received signal R (k), and for each different start position, correlating the pseudo-random sequence Dr(t-j) performing correlation operation on the sampled signals to obtain a channel impulse response of each sampling time point j, wherein the impulse response comprises the delay and the energy of each reflection after the main received signal;
correlation(Dr(t-j),R(k))/M＝Hc(j)＝H(j)+Hr(j),j＝-m,...0,1,...n；
the module M5 employs: if the correlation with the received sample signal is a pseudo-random sequence of the impulse sequence Dri，DriOnly one sampling time point in each pseudo random code bit period represents a pseudo random code, and by utilizing the correlation characteristic of the pseudo random sequence, when the value of M reaches a preset value, 1/M is ignored, and then the channel impulse response of each sampling time point j is obtained:
correlation(Dri(t-j),R(k))/M＝Hcp(j)＝Hp(j)+Hrp(j),j＝-m,...0,1,...n；
wherein Hcp(j) Is the impulse response of the channel; since the signal discontinuity or reflection point is usually some distance from the transmitting end, Hrp(j) Leave Hp(j) Has a certain delay of the main signal energy, Hcp(j) The energy when the energy of the middle distance main signal reaches a preset value is caused by signal discontinuity points or reflection; by analysis of Hcp(j) And obtaining the position and the reflected energy of the signal discontinuity point or the reflected point by the amplitude of each signal discontinuity point or the reflected energy and the time from the main signal energy.
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