CN109347501B - Fast automatic gain control method of intermediate frequency digital receiver - Google Patents
Fast automatic gain control method of intermediate frequency digital receiver Download PDFInfo
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- CN109347501B CN109347501B CN201811139065.9A CN201811139065A CN109347501B CN 109347501 B CN109347501 B CN 109347501B CN 201811139065 A CN201811139065 A CN 201811139065A CN 109347501 B CN109347501 B CN 109347501B
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Abstract
The invention discloses a fast automatic gain control method of an intermediate frequency digital receiver, which comprises the steps of firstly obtaining a signal intensity posterior knowledge table for judging the signal intensity, then obtaining an attenuation parameter posterior knowledge table, recording AD values of intermediate frequency output peak values of signals with different intensities under various attenuation conditions of a radio frequency front-end device, and using the AD values as the attenuation parameter posterior knowledge table for inquiring attenuation gears which need to be set by the radio frequency front-end device when the AD value of a certain intensity signal peak value is in a specified range. When the signal is small, the attenuation degree of the radio frequency front-end device is reduced after the first setting and query, and the setting and query process is carried out for one time. But the required setting times can be locked within 3 times in general, and the rapid automatic gain control of the receiver is realized.
Description
Technical Field
The invention relates to the technical field of radio monitoring in a wireless communication system, in particular to a quick automatic gain control method of an intermediate frequency digital receiver.
Background
With the development of the internet, the demand for radio communication is increasing, and the radio supervision work of government departments is also stressed. In radio monitoring equipment, receivers with digitized intermediate frequencies are widely used. In order to adapt to wide signal strength variation, an automatic gain control link is usually added to the receiver to dynamically adjust the attenuation level of the rf front-end device in the receiver.
In the conventional automatic gain control process of the receiver, the attenuation degree of the intermediate frequency signal is continuously adjusted according to the AD sampling value of the peak value of the intermediate frequency signal output by the radio frequency front end, and finally the AD sampling value of the peak value of the intermediate frequency signal is in a desired interval. For signals with the same strength, because attenuation parameters are nonlinearly related to a signal peak value AD value, when the signals are larger or smaller, the conventional automatic gain control process comprises more operations of inquiring and setting a radio frequency front-end device, and adjusting the attenuation degree and setting the radio frequency front-end device are relatively time-consuming processes. Therefore, a fast automatic gain control method for an if digital receiver is needed.
The technical defects are worthy of improvement.
Disclosure of Invention
In order to overcome the technical defects in the prior art, the invention provides a quick automatic gain control method of an intermediate frequency digital receiver, which overcomes the defect of low speed of the automatic gain control method of the conventional intermediate frequency digital receiver.
The technical scheme of the invention is as follows:
a fast automatic gain control method of an intermediate frequency digital receiver specifically comprises the following steps:
(1) acquiring data to generate a signal power look-up table: setting the attenuation of a radio frequency front-end device in receiver equipment to be maximum, inputting a single-tone signal to the receiver by using a signal source, changing the signal power from 20dBm to-40 dBm by taking 1dBm as a step, recording AD sampling values of intermediate frequency output peak values, corresponding to the signal power one by one, and recording the AD sampling values as a first part of a signal power query table; setting the attenuation of a radio frequency front-end device in receiver equipment to be 0, inputting a single-tone signal to a receiver by using a signal source, changing the signal power from-40 dBm to-100 dBm by taking 1dBm as a step, recording AD sampling values of intermediate frequency output peaks, corresponding to the signal power one by one, recording the AD sampling values as a second part of a signal power query table, and further generating the signal power query table;
(2) collecting data to generate an attenuation parameter lookup table: dividing the conversion result value of the used AD chip into several intervals, aiming at the signals of each power in the signal power query table in the step (1), respectively enabling the AD sampling value of the signal peak value to fall in each interval by adjusting the attenuation value of a radio frequency front-end device, and recording the attenuation parameters and the intervals in a one-to-one correspondence manner, thereby generating an attenuation parameter query table;
(3) determining the signal power according to a signal power look-up table: setting the attenuation of a radio frequency front-end device in the receiver equipment to be maximum, inquiring an AD sampling value of a peak value of an intermediate frequency signal, and finding a corresponding signal power value in the signal power inquiry table in the step (1) according to the inquired AD value; and (2) when the AD sampling value of the signal peak value is too small, setting the attenuation of a radio frequency front-end device in the receiver equipment to be 0, inquiring the AD sampling value of the intermediate frequency signal peak value, and finding a corresponding signal power value in the signal power inquiry table in the step (1) according to the inquired AD value.
(4) Determining attenuation parameters according to the attenuation parameter lookup table: and (4) determining attenuation parameters of the radio frequency front-end device to be configured according to the signal strength determined in the step (3) and the interval where the AD sampling value of the actual expected signal peak value is located, so that automatic gain control is completed once, and when the receiver scans the frequency band, automatic gain control is performed once every time the frequency is switched.
According to the present invention described above, in step (1), the generated signal power look-up table is divided into two parts: when the signal intensity is greater than-40 dBm, setting the attenuation of a radio frequency front-end device in the receiver equipment to be maximum, changing the signal power from 20dBm to-40 dBm by taking 1dBm as a step, recording AD sampling values of the intermediate frequency output peak value and corresponding to the signal power one by one;
when the signal intensity is less than-40 dBm, the attenuation of a radio frequency front-end device in the receiver equipment is set to be 0, the signal power is changed from-40 dBm to-100 dBm by taking 1dBm as stepping, and AD sampling values of the intermediate frequency output peak values are recorded and correspond to the signal power one by one.
According to the present invention described above, in the step (2), the main index of the attenuation parameter lookup table generated is all the signal power values included in the signal power lookup table described in the step (1), that is, power values stepped from-100 dBm to 20dBm by 1 dBm.
The secondary index of the attenuation parameter lookup table is determined according to the conversion value of the AD chip, for example, if the conversion value range of the 14-bit AD chip is-8192 to 8191, 10 intervals are divided from 0 to 8192 (the peak AD sampling value of the intermediate frequency signal is obtained by taking the absolute value for judgment). By adjusting the attenuation parameters of the radio frequency front-end device, the peak AD sampling values after signal conversion of each power can fall in 10 divided intervals respectively, and the attenuation parameters and the intervals are recorded in a one-to-one correspondence mode. If the attenuation parameters are adjusted to the maximum values (maximum and minimum) and the AD sampling cannot fall in the corresponding interval, the maximum attenuation parameters are recorded in the corresponding interval items, wherein the number of the intervals can be set arbitrarily.
According to the invention, in the steps (3) and (4), the signal power look-up table in the step (1) is used to determine the approximate strength of the monitored signal, and then the attenuation parameter look-up table in the step (2) is used to determine the rf front-end attenuation parameter which makes the peak value AD sampling value after the conversion of the intermediate frequency signal fall in the desired region, so as to complete the fast automatic gain control of the intermediate frequency digital receiver in a manner of setting the rf front-end for no more than 3 times.
The invention relates to an automatic gain control method of an intermediate frequency digital receiver, which is developed and designed by utilizing a software radio signal processing technology, has wide adaptability and is convenient to realize on common radio monitoring and controlling equipment. And quickly locking attenuation parameters required to be set by the radio frequency front-end device according to two look-up tables acquired in advance by utilizing posterior knowledge about the radio frequency front-end device, and finishing the quick automatic gain control process of the intermediate frequency digital receiver.
Drawings
The invention will be further described with reference to the following drawings and detailed description:
FIG. 1 is a block diagram of the overall flow of a conventional automatic gain control;
FIG. 2 is a flow chart of an implementation of fast automatic gain control according to an embodiment of the present invention;
FIG. 3 is a signal strength look-up table of an embodiment of the present invention;
fig. 4 is a lookup table of attenuation parameters for an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and technical advantages of the present invention more clearly apparent, the present invention will be further described and illustrated in detail with reference to the accompanying drawings and embodiments. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention, but not to limit the present invention.
Fig. 1 is a block diagram of the overall flow of conventional automatic gain control, and details of implementation are described as follows:
the purpose of the conventional automatic gain control is that through the control mechanism of the module 103, when the intensity of the input signal changes within a supported range in the automatic operation state of the device, the peak value AD sample value of the signal output by the module 102 can be relatively stably maintained within a certain interval. The conventional automatic gain control implementation process is as follows: the 103 module detects 102 the AD samples (absolute values) output by the module in real time and updates the recorded maximum values continuously in a small (millisecond) time slice, and when the maximum value is found to exceed a set threshold range, the 103 module issues an instruction to adjust 101 the attenuation value of the module to make the recorded signal peak value AD fall within a desired range. Due to the non-linear nature of the device, when the signal is large or small, the query and setup process needs to be cycled for several times to make the signal peak value AD fall in the desired region.
Fig. 2 is a flowchart of an implementation of fast agc according to an embodiment of the present invention, which corresponds to control logic functioning in module 103 in fig. 1, and is described in detail with reference to fig. 2 as follows:
step 201: the attenuation of the radio frequency front end device in the receiver equipment is set to be maximum, namely, the radio frequency attenuation (RF _ att) is set to be 30, the intermediate frequency attenuation (IF _ att) is set to be 20, after the parameters are set, the general radio frequency front end device has a tuning time to wait for the device to be stable and then outputs valid data, after the tuning time is finished, the previous signal peak value AD value holding value is cleared, and the step 202 is skipped.
Step 202: the signal peak AD value hold value, i.e. the maximum AD value occurring in this short time period, is recorded for a short time period (100 ms), and step 203 is skipped.
Step 203: and judging according to the maximum AD value recorded in the step 202, if the value is smaller than the set threshold, namely the signal intensity is smaller than-40 dBm, skipping to the step 204, and if the value is larger than the set threshold, skipping to the step 205 to continue execution.
Step 204: setting the attenuation of the radio frequency front-end device in the receiver equipment to 0, namely setting the radio frequency attenuation (RF _ att) to 0 and setting the intermediate frequency attenuation (IF _ att) to 0, wherein after the parameters are set, the general radio frequency front-end device has a tuning time to wait for the device to be stable and then outputs valid data, and after the tuning time is finished, clearing the previous signal peak value AD value holding value, and jumping to step 207.
Step 205: the corresponding signal power value is looked up in the "signal power look-up table" according to the AD maximum value recorded in step 202, and then the attenuation parameter to be set by the rf front-end device is found in the "attenuation parameter look-up table" according to the two screening conditions of the signal power value and the interval where the expected AD value is located.
Step 206: and setting according to the inquired attenuation value of the radio frequency front-end device to complete automatic gain control.
Step 207: the signal peak AD value hold value, i.e. the maximum AD value occurring during this short period of time, is recorded for a short period of time (100 ms), jumping to step 208.
Step 208: the corresponding signal power value is looked up in the "signal power look-up table" according to the AD maximum value recorded in step 202, and then the attenuation parameter to be set by the rf front-end device is found in the "attenuation parameter look-up table" according to the two screening conditions of the signal power value and the interval where the expected AD value is located.
Step 209: and setting according to the inquired attenuation value of the radio frequency front-end device to complete automatic gain control.
Fig. 3 is a signal strength look-up table, the contents of which are illustrated as follows:
the table is divided into two parts, namely a table of the radio frequency front-end device in a maximum attenuation state and a table of the radio frequency front-end device in a minimum attenuation state, wherein the maximum attenuation state is used for ensuring that the peak value of a large signal does not exceed the upper limit of an AD chip; correspondingly, the minimum attenuation is used so that the smaller signal peak is not lower than the minimum signal strength that can be measured by the AD chip. Therefore, by matching with the arrangement of the radio frequency front-end device, the table is inquired, and the strength of the signal in the interval of-100 dBm to 20dBm can be identified.
Fig. 4 is a table for a lookup of attenuation parameters, the contents of which are illustrated as follows:
the main query condition in the table is the signal strength, and the secondary query condition is the interval where the expected signal peak value AD is located, and the attenuation parameter which should be set by the radio frequency front-end device can be determined through the combination of the two screening conditions.
The above-mentioned embodiments, objects, technical solutions and technical advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (5)
1. A fast automatic gain control method of an intermediate frequency digital receiver is characterized by comprising the following steps:
(1) acquiring data to generate a signal power look-up table: setting the attenuation of a radio frequency front-end device in receiver equipment to be maximum, inputting a single-tone signal to the receiver by using a signal source, changing the signal power from 20dBm to-40 dBm by taking 1dBm as a step, recording AD sampling values of intermediate frequency output peak values, corresponding to the signal power one by one, and recording the AD sampling values as a first part of a signal power query table; setting the attenuation of a radio frequency front-end device in receiver equipment to be 0, inputting a single-tone signal to a receiver by using a signal source, changing the signal power from-40 dBm to-100 dBm by taking 1dBm as a step, recording AD sampling values of intermediate frequency output peaks, corresponding to the signal power one by one, recording the AD sampling values as a second part of a signal power query table, and further generating the signal power query table;
(2) collecting data to generate an attenuation parameter lookup table: dividing the conversion result value of the used AD chip into several intervals, aiming at the signals of each power in the signal power query table in the step (1), respectively enabling the AD sampling value of the signal peak value to fall in each interval by adjusting the attenuation value of a radio frequency front-end device, and recording the attenuation parameters and the intervals in a one-to-one correspondence manner, thereby generating an attenuation parameter query table;
(3) determining the signal power according to a signal power look-up table: setting the attenuation of a radio frequency front-end device in the receiver equipment to be maximum, inquiring an AD sampling value of a peak value of an intermediate frequency signal, and finding a corresponding signal power value in the signal power inquiry table in the step (1) according to the inquired AD value; when the AD sampling value of the signal peak value is too small, setting the attenuation of a radio frequency front-end device in the receiver equipment to be 0, inquiring the AD sampling value of the intermediate frequency signal peak value, and finding a corresponding signal power value in the signal power look-up table in the step (1) according to the inquired AD value;
(4) determining attenuation parameters according to the attenuation parameter lookup table: and (4) determining attenuation parameters of the radio frequency front-end device to be configured according to the signal strength determined in the step (3) and the interval where the AD sampling value of the actual expected signal peak value is located, so that automatic gain control is completed once, and when the receiver scans the frequency band, automatic gain control is performed once every time the frequency is switched.
2. The method as claimed in claim 1, wherein the signal power look-up table generated in step (1) is divided into two parts:
when the signal intensity is greater than-40 dBm, setting the attenuation of a radio frequency front-end device in the receiver equipment to be maximum, changing the signal power from 20dBm to-40 dBm by taking 1dBm as a step, recording AD sampling values of the intermediate frequency output peak value and corresponding to the signal power one by one;
when the signal intensity is less than-40 dBm, the attenuation of a radio frequency front-end device in the receiver equipment is set to be 0, the signal power is changed from-40 dBm to-100 dBm by taking 1dBm as stepping, and AD sampling values of the intermediate frequency output peak values are recorded and correspond to the signal power one by one.
3. The method as claimed in claim 1, wherein the main index of the generated fading parameter lookup table in step (2) is all signal power values included in the signal power lookup table in step (1), i.e., power values stepped from-100 dBm to 20dBm by 1 dBm.
4. The method as claimed in claim 3, wherein the secondary index of the fading parameter lookup table is determined according to a conversion value of an AD chip used.
5. The method according to claim 1, wherein in steps (3) and (4), the signal power look-up table in step (1) is used to determine the approximate strength of the monitored signal, and then the attenuation parameter look-up table in step (2) is used to determine the rf front-end attenuation parameter that makes the peak AD sample value after the if signal conversion fall in the desired region, so as to achieve the purpose of performing the fast automatic gain control of the if digital receiver without exceeding 3 times of setting the rf front-end.
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| US9144042B2 (en) * | 2008-03-06 | 2015-09-22 | Marvell World Trade Ltd. | Method for fast automatic power control of wireless transmitters |
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| WO2011093069A1 (en) * | 2010-01-27 | 2011-08-04 | Canon Kabushiki Kaisha | Subject information acquisition apparatus and subject information acquisition method |
| CN102231906A (en) * | 2011-06-22 | 2011-11-02 | 中兴通讯股份有限公司 | Gain control method and radio remote unit (RRU) |
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Denomination of invention: A Fast Automatic Gain Control Method for Intermediate Frequency Digital Receiver Effective date of registration: 20230913 Granted publication date: 20210730 Pledgee: Chengdu small business financing Company Limited by Guarantee Pledgor: CHENGDU DAGONG BOCHUANG INFORMATION TECHNOLOGY CO.,LTD. Registration number: Y2023510000214 |