CN110474699B - Method for improving direction-finding speed of single-channel amplitude-comparison direction-finding equipment - Google Patents
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Abstract
The invention discloses a method for improving the direction-finding speed of single-channel amplitude-comparison direction-finding equipment, which comprises the following steps: controlling a single-pole N-throw switch to sequentially conduct the antennas at intervals, and respectively extracting the maximum signal amplitude values of signals measured by the antennas by a direction-finding receiver; and (3) judging: whether there is one antenna: the maximum value of the signal amplitude is the largest, the difference value between the maximum value of the signal amplitude and the maximum value of the signal amplitude of other antennas is larger than a preset threshold T1, if the maximum value of the signal amplitude exists, two adjacent antennas are respectively opened, the maximum value of the signal amplitude is obtained, and the incoming wave direction of the signal is calculated through a three-antenna amplitude-comparison direction-finding algorithm. Otherwise, judging whether two antennas exist: the two antennas are conducted adjacently, the difference value of the maximum value of the signal amplitude is within a preset threshold T2, if yes, the antenna between the two antennas is opened, and the maximum value of the signal amplitude is obtained through the direction finding receiver; and calculating the incoming wave direction of the signal by a three-antenna amplitude-comparison direction-finding algorithm. The invention reduces the number of antennas for accumulating signals for direction finding and improves the single-channel amplitude-comparison direction finding processing speed.
Description
Technical Field
The invention relates to the technical field of radio communication and radio frequency spectrum monitoring, in particular to a method for improving the direction-finding speed of single-channel amplitude-comparison direction-finding equipment.
Background
In the field of radio communication and spectrum monitoring, in order to reduce the cost of direction-finding equipment, a single-channel amplitude-comparison direction-finding technology is generated, which is a technology that receiving equipment with only one radio-frequency receiving channel is used for receiving data among all antennas in a time-sharing manner, and finally the data is comprehensively processed to obtain the incoming wave direction of a signal. Due to the modulation of the signal or the disturbance of multipath, shielding and the like in the process of propagation, the amplitude of the signal reaching the direction-finding equipment antenna is not constant, the amplitude data applied by single-channel amplitude-to-direction measurement is generally the maximum value of the current amplitude within a period of time, and a certain time is needed to extract the maximum value of the signal. The specific implementation process is as follows: the method comprises the steps of assuming that a space is provided with N directional antennas which are uniformly distributed, connecting each antenna one by one through a single-pole N-throw switch by utilizing the principle of antenna electric scanning, obtaining the maximum amplitude value of the current antenna one by one through a single-channel direction finding receiver, selecting data of three corresponding antennas with the maximum signal power according to the maximum value extracted by each antenna, and obtaining the signal direction by applying a mature three-antenna amplitude-to-amplitude direction finding algorithm. Assuming that the time required for a single channel direction finding receiver to acquire the amplitude of one antenna signal is t0, the total time required to complete one scan is nxt 0. For situations where the signal hold time is not long enough (less than nxt 0) to support all antennas to perform maximum signal acquisition, unacceptable direction finding errors result.
Disclosure of Invention
The invention aims to provide a method for improving the direction-finding speed of single-channel amplitude-comparison direction-finding equipment, which is used for solving the problems that the maximum amplitude value of each antenna needs to be obtained one by one, the test speed is low, and if the signal holding time is not long enough, all the antennas cannot be supported to finish the maximum value acquisition, so that the direction-finding error is caused.
The invention solves the problems through the following technical scheme:
a method for improving the direction-finding speed of single-channel amplitude-comparison direction-finding equipment comprises N directional antennas which are uniformly distributed in the direction of 360 degrees, wherein N is an even number which is more than or equal to 6, the output ends of the directional antennas are respectively connected with the fixed end of a single-pole N-throw switch, the movable end of the single-pole N-throw switch is connected with a single-channel direction-finding receiver, and the testing step comprises the following steps:
step S100: controlling the single-pole N-throw switch to sequentially conduct the 1 st, 3 rd, … … th and N-1 st directional antennas, and respectively extracting the signal amplitude maximum values of the signals measured by the 1 st, 3 rd, … … th and N-1 st directional antennas by the single-channel direction-finding receiver;
the processing flow for extracting the signal amplitude is as follows:
the signal is processed in a single-channel direction-finding receiver through low-noise amplification, down-conversion, filtering and the like, then digital signals are obtained through analog-to-digital conversion with the sampling rate of 102.8MSPS, then 2048-point DFT processing is carried out in FPGA, the point with the maximum amplitude is searched in the DFT result, and the amplitude of the point is taken as the maximum amplitude of the current frequency point.
Step S200: and (3) judging: whether there is one directional antenna: the maximum value of the signal amplitude is the maximum and the difference value with the maximum value of the signal amplitude of other directional antennas is larger than a preset threshold T1, if the maximum value of the signal amplitude is larger than the preset threshold T1, the step S300 is carried out, and the situation is determined as a situation A; otherwise, judging whether two directional antennas exist: the two are conducted adjacently, the difference value of the maximum values of the signal amplitudes of the two is within a preset threshold T2, if yes, the step S400 is carried out, and the situation is determined as a situation B;
step S300: respectively opening two directional antennas adjacent to the directional antenna with the maximum signal amplitude through a single-pole N-throw switch, respectively acquiring the maximum signal amplitude corresponding to the two adjacent directional antennas through a single-channel direction-finding receiver, and calculating the incoming wave direction by adopting a three-antenna amplitude-comparison direction-finding algorithm;
step S400: the directional antenna in the middle of two directional antennas which are adjacently conducted and have the maximum difference value of the signal amplitude within a preset threshold T2 is turned on through a single-pole N-throw switch, the maximum value of the signal amplitude is obtained through a single-channel direction finding receiver, and the incoming wave direction of the signal is calculated through a three-antenna amplitude-comparison direction finding algorithm.
The method can realize single-channel amplitude-comparison direction finding by only using signal amplitude data of a part of directional antennas without turning on all the directional antennas, and improves the processing speed of direction finding. In case a, there is N/2+2 that needs to perform signal amplitude extraction, and the processing speed increasing ratio is: 1- (N/2+ 2)/N;
in case B, there is N/2+1 that needs to be extracted, and the processing speed is increased by the following ratio: 1- (N/2+ 1)/N. Both of these possibilities are 50% probable from the perspective of the spatial signal distribution. Therefore, the comprehensive improvement proportion eta of the method is as follows:
as can be seen from the above formula, the effective precondition of the method must satisfy eta is greater than or equal to 0, and N is greater than or equal to 3.
Because the space covered by a single directional antenna is increased if the number of the directional antennas is too small in engineering implementation, the gain of the directional antenna is reduced, the consistency of the directional antennas is not easy to control, and because certain directional antenna gain and direction-finding precision need to be ensured in equipment implementation, the number of the directional antennas of the direction-finding equipment in engineering is generally not lower than 6, and the number of the directional antennas of amplitude-comparing equipment is generally an even number, the method has universal applicability.
When the number N of the directional antennas is increased, the increased proportion eta is gradually increased and does not exceed 50% at most, so that the test time is shortened, and the problem of direction-finding errors caused by the fact that the maximum value acquisition cannot be completed due to the fact that the signal holding time is not long enough is solved. The time required for the antenna amplitude comparison and threshold decision, which are added several times at this time, is only a few clock cycles (in the order of nanoseconds), with negligible added processing delay.
Further, the 3dB beamwidth of the N directional antennas is 360 °/N.
Compared with the prior art, the invention has the following advantages and beneficial effects:
on the basis of a mature three-antenna amplitude comparison direction finding algorithm, the invention adopts a mode that one directional antenna is separated for carrying out one-time rough scanning, and then the appointed directional antenna is pertinently opened according to the rough scanning result, thereby reducing the number of directional antennas which need to accumulate signals for direction finding and achieving the purpose of improving the single-channel amplitude comparison direction finding processing speed.
Drawings
FIG. 1 is a schematic diagram of a hardware platform in the case of a 6-directional antenna according to the present invention;
fig. 2 is a schematic view of azimuth beam coverage of 6 directional antennas.
Detailed Description
The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.
Example 1:
fig. 1 includes schematic azimuth beam coverage diagrams of 6 directional antennas numbered 1-6 in fig. 2, where solid lines are directional antennas No. 1, 3, and 5, and dotted lines are directional antennas No. 2, 4, and 6. The-3 dB beamwidth of each directional antenna is 60 deg., and the-3 dB beams of adjacent directional antennas (e.g., directional antennas # 1 and # 2) intersect in spatial domain. The-8 dB beams spaced one directional antenna apart (e.g., directional antennas # 1 and # 3) intersect in the spatial domain. The-13 dB beams separating two directional antennas (e.g., directional antennas # 1 and # 4) intersect in the spatial domain. The intersection point of the directional antenna beam in the airspace is only used for determining the value of the setting threshold required in the method, and can be adjusted according to the actual test result of the directional antenna, which is not a mandatory requirement.
A method for improving direction-finding speed of single-channel amplitude-comparison direction-finding equipment is implemented by a hardware platform as shown in figure 1, directional antennas 1-6 which are uniformly distributed in azimuth direction, a single-pole six-throw switch and a single-channel direction-finding receiver, wherein the directional antennas 1-6 are respectively connected with six input ports of the single-pole six-throw switch, and an output port of the single-pole six-throw switch is connected to the single-channel direction-finding receiver.
The main processing flow for extracting the signal amplitude by the single-channel direction-finding receiver is as follows: the signal is processed in a single-channel direction-finding receiver through low-noise amplification, down-conversion, filtering and the like, then digital signals are obtained through analog-to-digital conversion with the sampling rate of 102.8MSPS, then 2048-point DFT processing is carried out in FPGA, the point with the maximum amplitude is searched in the DFT result, and the amplitude of the point is taken as the maximum amplitude of the current frequency point.
The testing steps are as follows:
controlling the single-pole six-throw switch to respectively conduct the directional antennas 1, 3 and 5, and extracting the maximum signal amplitude values corresponding to the directional antennas 1, 3 and 5 through the single-channel direction-finding receiver;
if signals exist in the airspace, the maximum value of the signal amplitude measured by one directional antenna in the tested directional antennas 1, 3 and 5 is far larger than or approximately equal to that of the adjacent directional antenna.
When the maximum value of the signal amplitude measured by one directional antenna (for example, 3) is far larger than (according to the antenna beam intersection condition setting threshold T1 of fig. 2) the other directional antennas (1 and 5) (defined as the condition a), the directional antennas (2 and 4) at the adjacent positions of the directional antenna (3) are respectively opened through the single-pole six-throw switch, and the maximum values of the signal amplitudes of the adjacent directional antennas (2 and 4) are obtained through the single-channel direction-finding receiver. And the maximum value of the signal amplitude of the directional antenna (No. 3) and the adjacent directional antenna (No. 2 and No. 4) is brought in by a three-antenna amplitude-comparison direction-finding algorithm, and the incoming wave direction of the signal is calculated. In case a, the number of directional antennas required by the single-channel direction finding receiver to extract signal amplitude is 5, and compared with the case of completing data extraction of all directional antennas one by one, the processing speed is increased 1/6.
When the signal amplitude value measured by one directional antenna (for example, the directional antenna 1) is approximately equal to (the threshold T2 is set according to the directional antenna beam intersection condition of fig. 2) one of the measured adjacent directional antennas (for example, the directional antenna 3) (defined as the condition B), the directional antenna (the directional antenna 2) in the middle of the two directional antennas is turned on through the single-pole six-throw switch, and the maximum value of the signal amplitude is obtained through the single-channel direction-finding receiver. And substituting the signal amplitudes of the current three directional antennas (No. 1, No. 2 and No. 3) by a three-antenna amplitude comparison direction finding algorithm to calculate the incoming wave direction of the signal. In case B, the number of directional antennas required by the single-channel direction finding receiver to extract signal amplitude is 4, and compared with the case where data extraction of all directional antennas is completed one by one, the processing speed is increased 1/3.
From the spatial signal distribution, the probability that case a and case B may occur is 50%. Then the method has a comprehensive improvement ratio eta to the direction finding speed under the condition of 6 directional antennas:
[(1/6)+(1/3)]/2＝1/4＝25％
in the direction finding process described by the method, all directional antennas do not need to be gated, and single-channel amplitude comparison direction finding can be realized by using signal amplitude data of a part of directional antennas so as to improve the direction finding processing speed.
The number of the directional antennas of the direction-finding system can be expanded to N, the 3dB beam width of each directional antenna is 360 degrees/N, and the N directional antennas are uniformly distributed in the range of 360 degrees in the azimuth direction.
The boost ratio corresponding to the number of common antennas is listed in table 1:
| number of antennas N | Increasing the |
| 6 | 0.25 |
| 8 | 0.3125 |
| 10 | 0.35 |
| 12 | 0.375 |
TABLE 1 boost ratio for common number of antennas
Although the present invention has been described herein with reference to the illustrated embodiments thereof, which are intended to be preferred embodiments of the present invention, it is to be understood that the invention is not limited thereto, and that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure.
Claims (2)
1. A method for improving the direction-finding speed of single-channel amplitude-comparison direction-finding equipment is characterized by comprising N directional antennas which are uniformly distributed in the direction of 360 degrees, wherein N is an even number which is more than or equal to 6, the output ends of the directional antennas are respectively connected with the fixed end of a single-pole N-throw switch, the movable end of the single-pole N-throw switch is connected with a single-channel direction-finding receiver, and the testing step comprises the following steps:
step S100: controlling the single-pole N-throw switch to sequentially conduct the 1 st, 3 rd, … … th and N-1 st directional antennas, and respectively extracting the signal amplitude maximum values of the signals measured by the 1 st, 3 rd, … … th and N-1 st directional antennas by the single-channel direction-finding receiver;
step S200: and (3) judging: whether there is one directional antenna: the maximum value of the signal amplitude is the maximum and the difference value between the maximum value of the signal amplitude and the maximum values of the signal amplitudes of other directional antennas is greater than a preset threshold T1, if the maximum value of the signal amplitude is greater than the maximum value of the signal amplitudes of other directional antennas, the step S300 is executed; otherwise, judging whether two directional antennas exist: the two are conducted adjacently, the difference value of the maximum signal amplitude values of the two is within a preset threshold T2, if yes, the step S400 is executed;
step S300: respectively opening two directional antennas adjacent to the directional antenna with the maximum signal amplitude through a single-pole N-throw switch, respectively acquiring the maximum signal amplitude corresponding to the two adjacent directional antennas through a single-channel direction-finding receiver, and calculating the incoming wave direction by adopting a three-antenna amplitude-comparison direction-finding algorithm;
step S400: the directional antenna in the middle of two directional antennas which are adjacently conducted and have the maximum difference value of the signal amplitude within a preset threshold T2 is turned on through a single-pole N-throw switch, the maximum value of the signal amplitude is obtained through a single-channel direction finding receiver, and the incoming wave direction of the signal is calculated through a three-antenna amplitude-comparison direction finding algorithm.
2. The method for improving the direction-finding speed of the single-channel direction-finding equipment with the amplitude-comparison according to claim 1, wherein the 3dB beam width of the N directional antennas is 360 degrees/N.
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