A test method for fm broadcasting to aeronautical navigation class b1 interference protection standard
A test method and aviation navigation technology, applied in the field of communication, can solve the problems that there is no B1 protection standard level test method, and it is impossible to find the FM signal level, so as to achieve simple and effective test process, simplified test method, and simplified level combination Effect
Inactive Publication Date: 2017-11-03
WUHAN UNIV OF SCI & TECH
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[0020] According to the above-mentioned B1 interference judgment standard, when three FM signals that meet the frequency combination conditions form B1 interference, their level combinations are infinite, that is, there are infinitely many level combinations that meet these three necessary conditions. In the test It is impossible to find the lowest FM signal level, that is, the protection standard level
[0021] Therefore, according to Recommendation ITU-R SM.1140, in addition to the B1 interference test experiment of infinitely many FM level combinations, according to the investigation of the inventor, there is currently no relevant and effective B1 protection standard level test method
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[0034] The present invention will be further explained below in conjunction with the accompanying drawings, but the following examples should not be construed as limiting the present invention.
[0035] Firstly, the principle of Type B1 interference is given. The broadcast signal outside the aviation frequency band makes the air navigation receiver enter nonlinearity, which may cause interactive modulation on the air navigation receiver, which is called Type B1 interference. To generate this type of interference, at least two broadcast signals are required and there must exist a frequency relationship that, in a non-linear process, produces intermodulation products on the useful RF channel used by the aeronautical receiver. One of the broadcast signals must have sufficient amplitude to put the receiver into the non-linear region.
[0036] The third-order frequency intermodulation situation is:
[0037] f A = 2f 1 -f 2 The case of two signals
[0038] f A =f 1 +f 2 -f ...
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The invention discloses a test method for FM broadcasting to aviation navigation B1 interference protection standard. Through theoretical analysis, the test of three FM signal f1≥f2>f3 protection standard levels satisfying the B1 interference frequency combination condition is simplified as the To test the f1 cut-off value of the FM signal with the highest frequency, first increase the levels of three FM signals at the same time until B1 interference occurs, and then increase the f2 and f3 signal levels at the same time when B1 interference exists, and then gradually decrease The level of f1, when the level of f1 is basically stable and no longer decreases with the increase of the signal levels of f2 and f3, this stable signal level of f1 can be determined as the protection standard level. This method simplifies the combination of levels, and the test process is simple and effective.
Description
technical field [0001] The invention relates to the technical field of communication, in particular to an electromagnetic compatibility test method between 87-108MHz broadcasting service and 108-118MHz aviation navigation service. Background technique [0002] With the development of FM broadcasting business and civil aviation business, the interference of 87-108MHz FM broadcasting to 108-118MHz aviation navigation business is becoming more and more severe. In some areas, it has even seriously interfered with the safe operation of civil aviation. Devices and methods are in increasing demand. [0003] ITU started to study the electromagnetic compatibility between FM broadcasting service and aeronautical radio service very early, and issued relevant proposals about compatibility analysis one after another. Recommendation ITU-R SM.1009-1, "Compatibility between 87-108MHz FM broadcasting service and 108-137MHz aeronautical radio service", introduces the analysis and evaluation ...
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IPC IPC(8): H04B17/00
Inventor 左韬赵玉
Owner WUHAN UNIV OF SCI & TECH