CN109768833B - Method for improving dynamic range of receiver and receiver - Google Patents
Method for improving dynamic range of receiver and receiver Download PDFInfo
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- CN109768833B CN109768833B CN201910252175.4A CN201910252175A CN109768833B CN 109768833 B CN109768833 B CN 109768833B CN 201910252175 A CN201910252175 A CN 201910252175A CN 109768833 B CN109768833 B CN 109768833B
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Abstract
A method for improving the dynamic range of a receiver and the receiver relate to the field of receivers in a space optical communication system, and the method comprises the following steps: after the received optical signal is amplified, the signal attenuation is carried out through an adjustable attenuator, the attenuated optical signal and local oscillator laser are subjected to coherent detection and reception together, and the attenuated optical signal and the local oscillator laser are converted into an electric signal to be subjected to digital signal processing; and acquiring the signal power value calculated in the digital signal processing in real time, and adjusting the attenuation coefficient of the adjustable attenuator according to the comparison result of the signal power value and the threshold value. On the premise of ensuring the sensitivity, the invention not only considers the real-time property and the detection capability of small signals, but also reduces the distortion when large signals pass through, and improves the dynamic range of the receiver.
Description
Technical Field
The present invention relates to the field of receivers in spatial optical communication systems, and in particular, to a method for improving the dynamic range of a receiver and a receiver.
Background
The space optical communication technology combines the advantages of optical fiber communication and microwave communication, has the advantages of high transmission code rate, small dimension, strong confidentiality and the like due to high working frequency and strong directivity of laser communication, does not need to lay a large number of optical fibers, and can greatly reduce the cost, so the space optical communication technology becomes a hotspot for inputting a large amount of manpower and material resources for research of various countries after the feasibility of the space optical communication technology is verified.
However, due to the randomness of the air channel, particles such as gas molecules, snow, fog, aerosol, etc. in the atmosphere can cause absorption and dispersion of light, especially in case of strong turbulence, the optical signal is easily and severely interfered, and in addition, the space optical communication is generally performed between two mobile platforms, the transmitting and receiving antenna is slightly deviated during the communication process, the intensity of the optical signal reaching the receiver generates a relatively large attenuation, and the signal is very small. In the better spatial channel condition, the signal sent by the transmitting end is larger, which may result in the received signal being too large.
Therefore, it is necessary to research the dynamic range of the receiver in the spatial optical communication system. In order to increase the dynamic range of a receiver in an optical communication system, some solutions have been proposed by researchers, but in many methods, the adjustment time is too long, so that the real-time requirement cannot be met, and the dynamic range of the received signal power is increased only in a limited way.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method for improving the dynamic range of a receiver and the receiver, which not only considers the real-time property and the detection capability of small signals, but also reduces the distortion when large signals pass through and improves the dynamic range of the receiver on the premise of ensuring the sensitivity.
To achieve the above object, in one aspect, a method for improving the dynamic range of a receiver is provided, which includes the steps of:
after the received optical signal is amplified, the signal attenuation is carried out through an adjustable attenuator, the attenuated optical signal and local oscillator laser are subjected to coherent detection and reception together, and the attenuated optical signal and the local oscillator laser are converted into an electric signal to be subjected to digital signal processing;
and acquiring the signal power value calculated in the digital signal processing in real time, and adjusting the attenuation coefficient of the adjustable attenuator according to the comparison result of the signal power value and the threshold value.
Preferably, the threshold includes a highest threshold and a lowest threshold, and when the signal power value is greater than the highest threshold, the attenuation coefficient is increased; when the signal power value is smaller than the lowest threshold value, reducing the attenuation coefficient; and when the lowest threshold value is less than or equal to the signal power value and less than or equal to the highest threshold value, keeping the attenuation coefficient unchanged.
Preferably, the attenuation coefficient has a highest threshold value and a lowest threshold value, and when the signal power value is greater than the highest threshold value or less than the lowest threshold value: if the attenuation coefficient is equal to or greater than the highest threshold value, the attenuation coefficient is kept at the highest threshold value; if the attenuation coefficient is equal to or less than the minimum threshold value, the attenuation coefficient is kept at the minimum threshold value; and if the lowest threshold value is less than the attenuation coefficient and less than the highest threshold value, setting the adjusted attenuation coefficient.
Preferably, a corresponding table of the analog voltage value and the attenuation coefficient is preset, the analog voltage value corresponding to the attenuation coefficient to be increased or decreased is obtained through the corresponding table, and the attenuation coefficient change of the adjustable attenuator is controlled by using the corresponding analog voltage value.
In another aspect, a receiver is provided, which is suitable for a spatial optical communication system, and includes:
a pre-optical amplifier for amplifying a received signal;
the adjustable attenuator is used for carrying out preliminary attenuation on the signal amplified by the preposed optical amplifier;
the local oscillator laser is used for generating local oscillator laser;
the integrated coherent receiver is used for completing coherent detection and reception of the preliminarily attenuated optical signal and the local oscillator laser and converting the optical signal and the local oscillator laser into an electric signal;
an analog-to-digital converter for converting an analog signal output by the integrated coherent receiver into a digital signal;
the digital signal processing module is used for receiving the digital signal, finishing signal processing and calculating a signal power value through a real-time algorithm;
the control module is used for accessing the digital signal processing module in real time, reading the signal power value and adjusting the attenuation coefficient of the adjustable attenuator according to the comparison result of the signal power value and the threshold value;
and the digital-to-analog converter is used for converting the digital signal output by the control module into an analog signal and inputting the analog signal to the adjustable attenuator.
Preferably, the threshold includes a highest threshold and a lowest threshold, the attenuation coefficient has the highest threshold and the lowest threshold, and the adjusting, by the control module, the attenuation coefficient according to the comparison result between the signal power value and the threshold includes:
when the signal power value is higher than the highest threshold value, adding 1 to the attenuation coefficient; if the attenuation coefficient after adding 1 is larger than or equal to the highest threshold value, keeping the attenuation coefficient at the highest threshold value, otherwise keeping the attenuation coefficient after adding 1;
when the signal power value is lower than the lowest threshold value, subtracting 1 from the attenuation coefficient; and if the attenuation coefficient after subtracting 1 is less than or equal to the lowest threshold value, keeping the attenuation coefficient at the highest lower limit value, and otherwise, keeping the attenuation coefficient after subtracting 1.
Preferably, the control module is preset with a corresponding table of an analog voltage value and an attenuation coefficient, and after receiving the signal power value output by the digital signal processing module, the control module compares the signal power value with a threshold value to obtain the attenuation coefficient; the control unit obtains an analog voltage value corresponding to the attenuation coefficient by inquiring the corresponding table, calculates a digital voltage value corresponding to the analog voltage value, and converts the digital voltage value into an analog voltage value through the digital-analog converter to be used as an input voltage value of the adjustable attenuator.
Preferably, the digital signal processing module calculates the signal power value in real time and stores the signal power value in a register, and the control unit reads the signal power value in the register in a circulating manner and compares the signal power value with the threshold value.
Preferably, the attenuator is preset with an initial value, and the initial value is an attenuation coefficient by which the attenuated signal can reach the minimum bit error rate under the condition of the designated receiving sensitivity.
Preferably, an automatic gain control circuit is arranged inside the integrated coherent receiver, and is used for controlling the magnitude of the electric signal through automatic gain.
One of the above technical solutions has the following beneficial effects:
1. by using the preamplification, the integrated coherent reception and the adjustable attenuator in a matching way, the power range of the receivable signals under the requirement of the bit error rate index can be obviously improved, the detection capability of small signals can be improved on the premise of ensuring the sensitivity, and the distortion problem can be solved when large signals pass through.
2. The digital signal processor, the adjustable attenuator and the control module are arranged to form an effective closed-loop control system, so that the tracking speed of the dynamic range can be obviously improved, the real-time requirement can be met, and the complexity of a circuit and an algorithm can be reduced.
Drawings
Fig. 1 is a schematic structural diagram of a receiver according to an embodiment of the present invention;
FIG. 2 is a flow chart of the control module adjusting the attenuation factor in an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
The invention provides an embodiment of a method for improving the dynamic range of a receiver, which comprises the following steps:
the optical signal received by the receiver is amplified with controllable gain to improve the signal-to-noise ratio. The amplified optical signal is subjected to signal attenuation through an adjustable attenuator; the attenuated optical signal and the local oscillator laser are subjected to coherent detection and reception together and converted into an electric signal. The converted electric signal is subjected to analog-to-digital conversion and then digital signal processing. The digital signal processing process comprises the following steps: and finishing the depolarization multiplexing, clock synchronization, frequency offset estimation, phase estimation, digital carrier recovery and judgment of the signal, and calculating the power value of the signal in real time. The control module obtains the signal power value calculated in the digital signal processing in real time, and adjusts the attenuation coefficient of the adjustable attenuator according to the comparison result of the signal power value and the threshold value.
The threshold values comprise a highest threshold value and a lowest threshold value, and when the signal power value is greater than the highest threshold value, the attenuation coefficient is increased; when the signal power value is smaller than the lowest threshold value, reducing the attenuation coefficient; and when the lowest threshold value is less than or equal to the signal power value and less than or equal to the highest threshold value, keeping the attenuation coefficient unchanged.
Preferably, the amount of attenuation factor adjustment per pass is plus 1 or minus 1. And the adjustable attenuator is provided with a highest threshold value and a lowest threshold value, and when the signal power value is greater than the highest threshold value or the signal power value is less than the lowest threshold value: when the attenuation coefficient is equal to or greater than the highest threshold value, the attenuation coefficient is maintained at the highest threshold value; when the attenuation coefficient is equal to or less than the minimum threshold value, the attenuation coefficient is kept at the minimum threshold value; when the lowest threshold value is less than the attenuation coefficient and less than the highest threshold value, the adjustable attenuator sets the adjusted attenuation coefficient.
Preferably, a corresponding table of the analog voltage value and the attenuation coefficient is preset, the analog voltage value corresponding to the attenuation coefficient to be adjusted is obtained through the corresponding table, and the analog voltage value is used as the input voltage value of the adjustable attenuator to control the attenuation coefficient change of the adjustable attenuator.
According to the method, as shown in fig. 1, an embodiment of a receiver is provided, which is suitable for a spatial optical communication system, and includes a pre-optical amplifier, an adjustable attenuator, a local oscillator laser, an integrated coherent receiver, an analog-to-digital converter, a digital signal processing module, a control module, and a digital-to-analog converter.
Specifically, the front-end optical amplifier can amplify the optical signal from the link with controllable gain according to the signal power, so as to improve the signal-to-noise ratio. The optical signal is amplified and enters an adjustable attenuator to be primarily attenuated. The adjustable attenuator will set an initial value, which is the attenuation coefficient at which the attenuated signal can reach the minimum bit error rate under the condition of the specified receiving sensitivity.
The local oscillator laser is used for generating local oscillator laser, and the attenuated optical signal and the local oscillator laser are sent to the integrated coherent receiver for coherent detection and reception and are converted into an electric signal; meanwhile, an automatic gain control circuit is arranged in the integrated coherent receiver and is used for initially automatically adjusting the gain according to the size of the electric signal, and when the electric signal is smaller, the gain is at a larger value, so that the signal can be amplified to a proper value; when the signal is larger, the automatic gain module controls to adjust the gain to be smaller.
The electric signal output by the integrated coherent receiver is converted into a digital signal by an analog-digital converter and then input into a digital signal processing module for processing. The digital signal processing module completes the depolarization multiplexing, clock synchronization, frequency offset estimation, phase estimation, digital carrier recovery and judgment of the signal, and calculates the signal power value through a real-time algorithm.
The digital signal processing module stores the signal power value calculated in real time in a register, and the control module circularly reads the signal power value in the register and compares the signal power value with a threshold value and a threshold value to obtain an adjusted attenuation coefficient.
As shown in fig. 2, taking the signal power value Val read by the control module at one time as an example, the threshold includes a highest threshold V _ thr _ H and a lowest threshold V _ thr _ L, and the specific procedure for comparing and adjusting the attenuation coefficient is as follows:
s1, the control module reads a signal power value Val from the digital signal processing module.
S2, judging whether the read Val is larger than V _ thr _ H, and if so, entering S3; if not, proceed to S6.
S3, adding 1 to the attenuation coefficient A to obtain an adjusted attenuation coefficient A1。
S4, judging A1Whether the maximum threshold value A _ H of the adjustable attenuation coefficient is larger than or equal to the maximum threshold value A _ H of the adjustable attenuation coefficient or not is judged, and if yes, the step is carried out to S5; if not, proceed to S11.
And S5, setting the attenuation coefficient of the adjustable attenuator to be A _ H, and ending.
S6, judging whether the read Val is smaller than V _ thr _ L, and if so, entering S8; if not, proceed to S7.
And S7, keeping the attenuation coefficient of the adjustable attenuator unchanged.
S8, the attenuation coefficient A needs to be reduced by 1 to obtain an adjusted attenuation coefficient A2。
S9, judging A2Whether the value is less than or equal to the lowest threshold value A _ L of the adjustable attenuation coefficient, if so, entering S10; if not, proceed to S11.
And S10, setting the attenuation coefficient of the adjustable attenuator to be A _ L, and ending.
S11, setting the attenuation coefficient of the adjustable attenuator to obtain the adjusted attenuation coefficient, and setting A according to the condition of adding 1 or subtracting 11Or A2And then, the process is ended.
In addition, the control module is preset with a corresponding table of an analog voltage value and an attenuation coefficient, and after receiving the signal power value output by the digital signal processing module, the control module obtains the adjusted attenuation coefficient according to the steps. Then look up the corresponding table to obtain the analog voltage value corresponding to the attenuation coefficient. Because the control unit outputs digital voltage and the adjustable attenuator needs to input analog voltage, the digital-analog converter calculates the analog voltage value found in the corresponding table into a digital voltage value, then outputs the digital voltage value to the digital-analog converter to be converted into an analog voltage value, and takes the converted analog voltage as the input voltage value of the adjustable attenuator so as to adjust the adjustable attenuator.
In the above embodiments, the pre-optical amplifier may improve the signal-to-noise ratio, but the signal may be amplified too much, so that automatic gain adjustment of the integrated coherent receiver is employed. But the dynamic range of the automatic gain adjustment of the integrated coherent receiver is only about 10dB, so that the signal is further adjusted through the digital signal processing module and the control module and the adjustable attenuator, and when the signal of the integrated coherent receiver is too large, the problem that the signal can not be adjusted to a proper value beyond the linear range of the gain adjustment can be solved.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.
Claims (7)
1. A method for increasing the dynamic range of a receiver, comprising the steps of:
after the received optical signal is amplified, the signal attenuation is carried out through an adjustable attenuator, the attenuated optical signal and local oscillator laser are subjected to coherent detection and reception together, and the attenuated optical signal and the local oscillator laser are converted into an electric signal to be subjected to digital signal processing;
acquiring a signal power value calculated in digital signal processing in real time, and adjusting the attenuation coefficient of the adjustable attenuator according to the comparison result of the signal power value and a threshold value;
the threshold comprises a highest threshold and a lowest threshold, the attenuation coefficient has the highest threshold and the lowest threshold, and the control module adjusts the attenuation coefficient according to the comparison result of the signal power value and the threshold comprises the following steps:
when the signal power value is higher than the highest threshold value, adding 1 to the attenuation coefficient; if the attenuation coefficient after adding 1 is larger than or equal to the highest threshold value, keeping the attenuation coefficient at the highest threshold value, otherwise keeping the attenuation coefficient after adding 1;
when the signal power value is lower than the lowest threshold value, subtracting 1 from the attenuation coefficient; and if the attenuation coefficient after subtracting 1 is less than or equal to the lowest threshold value, keeping the attenuation coefficient at the lowest threshold value, and otherwise, keeping the attenuation coefficient after subtracting 1.
2. The method for increasing the dynamic range of a receiver of claim 1, wherein: presetting a corresponding table of the analog voltage value and the attenuation coefficient, obtaining the analog voltage value corresponding to the attenuation coefficient needing to be increased or decreased through the corresponding table, and controlling the attenuation coefficient change of the adjustable attenuator by adopting the corresponding analog voltage value.
3. A receiver adapted for use in a spatial optical communication system, comprising:
a pre-optical amplifier for amplifying a received signal;
the adjustable attenuator is used for carrying out preliminary attenuation on the signal amplified by the preposed optical amplifier;
the local oscillator laser is used for generating local oscillator laser;
the integrated coherent receiver is used for completing coherent detection and reception of the preliminarily attenuated optical signal and the local oscillator laser and converting the optical signal and the local oscillator laser into an electric signal;
an analog-to-digital converter for converting the electrical signal output by the integrated coherent receiver into a digital signal;
the digital signal processing module is used for receiving the digital signal, finishing signal processing and calculating a signal power value through a real-time algorithm;
the control module is used for accessing the digital signal processing module in real time, reading the signal power value and adjusting the attenuation coefficient of the adjustable attenuator according to the comparison result of the signal power value and the threshold value;
the digital-to-analog converter is used for converting the digital signal output by the control module into an analog signal and inputting the analog signal to the adjustable attenuator;
the threshold comprises a highest threshold and a lowest threshold, the attenuation coefficient has the highest threshold and the lowest threshold, and the control module adjusts the attenuation coefficient according to the comparison result of the signal power value and the threshold comprises the following steps:
when the signal power value is higher than the highest threshold value, adding 1 to the attenuation coefficient; if the attenuation coefficient after adding 1 is larger than or equal to the highest threshold value, keeping the attenuation coefficient at the highest threshold value, otherwise keeping the attenuation coefficient after adding 1;
when the signal power value is lower than the lowest threshold value, subtracting 1 from the attenuation coefficient; and if the attenuation coefficient after subtracting 1 is less than or equal to the lowest threshold value, keeping the attenuation coefficient at the lowest threshold value, and otherwise, keeping the attenuation coefficient after subtracting 1.
4. The receiver of claim 3, wherein: the control module is preset with a corresponding table of an analog voltage value and an attenuation coefficient, and after receiving the signal power value output by the digital signal processing module, the control module compares the signal power value with a threshold value to obtain the attenuation coefficient; the control module obtains an analog voltage value corresponding to the attenuation coefficient by inquiring the corresponding table, calculates a digital voltage value corresponding to the analog voltage value, and converts the digital voltage value into an analog voltage value through a digital-to-analog converter to be used as an input voltage value of the adjustable attenuator.
5. The receiver of claim 3, wherein: the digital signal processing module calculates the signal power value in real time and stores the signal power value in a register, and the control module circularly reads the signal power value in the register and compares the signal power value with the threshold value.
6. The receiver of claim 3, wherein: the adjustable attenuator is preset with an initial value, and the initial value is an attenuation coefficient of which the signal can reach the minimum bit error rate after attenuation under the condition of appointed receiving sensitivity.
7. The receiver of claim 3, wherein: and an automatic gain control circuit is arranged in the integrated coherent receiver and is used for controlling the magnitude of the electric signal through automatic gain.
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| CN113676257B (en) * | 2021-08-19 | 2022-09-23 | 青岛海信宽带多媒体技术有限公司 | Optical module and optical module automatic gain control method |
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| JP4826514B2 (en) * | 2007-03-14 | 2011-11-30 | 株式会社日立製作所 | Optical transmission apparatus and control method thereof |
| JP5034770B2 (en) * | 2007-08-16 | 2012-09-26 | 富士通株式会社 | Coherent optical receiver and optical communication system |
| JP5700050B2 (en) * | 2010-11-18 | 2015-04-15 | 日本電気株式会社 | Coherent light receiving apparatus and coherent light receiving method |
| CN202168083U (en) * | 2011-07-17 | 2012-03-14 | 湖北久之洋红外***有限公司 | Photoelectric detecting receiving device with large dynamic range |
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| JP6536072B2 (en) * | 2015-02-20 | 2019-07-03 | 富士通株式会社 | Optical transmission apparatus and received light power control method |
| CN106226972A (en) * | 2016-08-31 | 2016-12-14 | 武汉光迅科技股份有限公司 | A kind of semiconductor optical amplifier operation control method and system |
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