Pseudo-Signal Interference Regularity of Single-Frequency Electromagnetic Radiation to Stepped-Frequency Radar

Abstract

When typical radar equipment is subjected to single-frequency electromagnetic radiation, the radar display interface forms a pseudo-signal, resulting in the misjudgment of real targets. Based on the working principle of stepped-frequency radar ranging, the effect mechanism of radar equipment pseudo-signal interference is revealed. Taking a Ku band stepped-frequency ranging radar as the test object, the pseudo-signal interference effect test of single-frequency electromagnetic radiation is carried out in this study. The pseudo-signal level value of 6 dBmV is selected as the sensitive criterion of the pseudo-signal interference effect. Through experiments, the variation curves of the pseudo-signal level values of the sensitive frequency bands and the typical frequency points inside and outside the band with the field strength of the single-frequency interference are obtained. Based on the nonlinear distortion analysis of the receiving circuit, the variation laws of the pseudo-signal level values inside and outside the band are explained, respectively. The experimental results show that there are at least seven pseudo-signal interference-sensitive bands in the tested radar, and the first pseudo-signal strength is only related to the interference signal strength. The essence of the second type of pseudo-signal interference is intermodulation interference, and the pseudo-signal level is related to the interference signal and the useful signal strength.

Generation Mechanism and Characteristic Analysis of Dual-Frequency Pseudo-Signal Interference of the Swept-Frequency Radar

“…In order to find out the distance of the "hill" type pseudosignal, ignoring the influence of the third exponential term in formula (16), formula ( 16) is normalized:…”

“…When the interference field strength is strong, the pseudo-signal strength even exceeds the true echo signal strength, causing the radar to misjudge [13]. e authors in [14] pointed out that the single-frequency signal whose jamming frequency is located in the working frequency band of the radar can cause false alarm interference to the radar, but the target characteristics of the false alarm interference were not analyzed. e author in [15] believes that singlefrequency interference can cause pseudo-signal interference on the display interface of the FM CW radar, but the abovementioned documents do not involve radar multifrequency pseudo-signal interference.…”

“…e Ku-band CW radar antenna is small in physical size, has good portability and ranging functions, and is widely used in short-range tracking and guidance [16]. In this paper, a Ku-band scanning continuous wave ranging radar is taken as the test object, and the single frequency and dualfrequency continuous wave electromagnetic radiation pseudo-signal interference effect tests are carried out in and out of the radar operating frequency band.…”

Study on the Law and Mechanism of the Third-Order Intermodulation False Alarm Effect of the Stepped Frequency Ranging Radar

“…If the frequency hopping time t r and step frequency ∆f * are certain, the delay time t d in the acquisition moment t k = kt r + t d is uncertain, which will also make the false alarm signal uncertain. In the actual imaging, the actual value of the false alarm target distance should also be combined with the selection of the radar signal parameters (t r and ∆f * ) to determine whether there is distance redundancy and other related information [19][20][21]. If the radar signal parameters meet the tight constraint conditions, the unambiguous distance, corresponding to the sub-period of the transmitting signal is r τ = ct r /2.…”

“…Research on the radar's false target is mostly aimed at information interference, and there is relatively less research on the non-information interference [15,16]. In the test of the radar EMI effect, it is found that when the interference frequency falls into the filter bandwidth, it will not only produce a blocking effect on the radar, but will also cause the radar to produce a false target response, which seriously affects the effective judgment of the battlefield situation [17,18]. In addition, the out-of-band dualfrequency EMI also causes the radar to produce a false target response similar to the in-band single frequency, therefore, it is necessary to study the radar's dual-frequency false target response mechanism.…”