For a long time, the modular design has been the mainstream implementation method of missile-borne telemetry and control equipment. However, there is no uniform standard for information interaction between modules. The development unit defines it according to its own technical and signal characteristics. The way of definition directly affects or determines the difficulty of implementing missile-borne telemetry and control equipment. In order to develop an efficient internal interconnection technology for missile-borne telemetry and control equipment, so that the connection of modules is simpler and more efficient, and the degree of generalization is higher when the performance requirements of missile-borne telemetry and control equipment become more complex, this paper divides the missile-borne telemetry and control equipment into three core modules and function expansion modules,and defines an efficient module-level bus interface form and protocol. The bus includes the input and output of primary power supply, secondary power supply, and internal cross-linked signals. The signal interaction adopts the form of a half-duplex bus. Each module can access the bus online and edit the bus online. Through design and experimental verification, the bus design method simplifies the external interface of the missile-borne telemetry and control equipment, and enables convenient and efficient online generation of telemetry PCM (Pulse Code Modulation) code stream. The function expansion module can be freely added or reduced without increasing the hardware burden of the bus interface, making the missile-borne telemetry and control equipment highly versatile.

TT&C communication link of sun pointing satellite in sun-synchronous orbit is easy to be interrupted due to the gain pattern interference area of the satellite’s TT&C antennas which are placed in traditional way. In order to reduce this kind of communication link interruption, the antennas’ placement on the satellite should be optimized by taking advantage of the characteristic that the orbital plane of the sun-synchronous orbit and the solar vector maintain a relatively fixed. In this paper, the concrete realization process of TT&C antennas’ placement for sun pointing satellite in sun-synchronous orbit is given through a simulation example, and the recommended installation angle of the TT&C antennas for sun pointing satellites in different sun-synchronous orbit are also provided as a reference.

The living environment of satellite navigation and positioning equipment is increasingly complex and severe,all kinds of electronic countermeasures,interference and deception are very fierce,and man-made interference has become the focus of satellite navigation and positioning security and confrontation. In view of the shortcomings of traditional means to effectively deal with the complexity, comprehensiveness and systematization of interference,the paper ,based on the analysis of OODA ring theory and practice transformation, combined with the overall counter process of interference and anti-interference in complex environment, optimized operation, coupled with satellite navigation and positioning security and counter, innovative satellite navigation and positioning security and counter non-directional circular link which is based on environment awareness, screening isolation, detection and recognition, performance evaluation, strategic planning, counter attack-return visit feedback, reperception. The seven links of expansion and mapping are analyzed and demonstrated. By introducing the concepts of loop and undirected, the operation mechanism of nested iteration and guided transmission of cyclic outer loop and loop in link is not only realized, but also the freedom of the inner loop is optimized, so that links are interconnected and independent, and loop but not directed, effectively enhance the safety of satellite navigation and positioning and the robustness of confrontation. The design idea of the paper can accelerate the realization of the dynamic closed-loop loop of cyclic link, improve the overall efficiency of countermeasure, and has certain reference value in practical application and technology demonstration.

The sum and difference channels of Kaband dual channel telemetry equipment have phase differences, which can vary with environmental changes. Phase correction is required at the baseband terminal to achieve phase difference correction and ultimately achieve autonomous tracking of the target. In the shooting range, baseband phase calibration was usually achieved by setting up calibration rods, which can achieve the purpose of phase calibration. However, with the expansion of telemetry equipment in the field of combat, it has expanded to areas such as deep sea and plateau. Due to the various limitations of these special location environments on setting up calibration rods, this article focuses on studying how to achieve the purpose of calibrating the phase zero value of the differential channel, without setting up calibration rods, transmit signals through biased antennas in plateau environments. This article presents the principle and method of rodless calibration based on biased antennas, and verifies the effectiveness of the proposed method through experiments.

Accurate measurement of underwater terrain in coastal areas is the key to human activities in the ocean. Synthetic aperture radar (SAR) provides a new means for the detection of shallow sea terrain. TerraSAR-X bunching mode can obtain highresolution SAR data with a long integration time, so that the seabed terrain of shallow sea can be inverted more accurately. Traditional SAR image underwater terrain detection is based on the assumption of constant wave period, which not only needs to know the initial water depth to solve the wave period, but also brings some errors to the detection results. In this paper, an underwater terrain detection method based on subaperture images is proposed. A SAR image is decomposed into subaperture images with fixed multiscene time intervals, and the time interval between subaperture images is used to solve the changing wave period, so as to obtain more accurate underwater terrain. The TerraSAR-X data of Wuzhizhou Island in Hainan Province was used to verify the feasibility of this method. The results obtained by inversion of this method were compared with the GEBCO data, and it was found that the two were in good agreement（the MAE was 2.8m and the MRE was 23.91%）. It is proved that this method has great potential for retrieving water depth in shallow sea.

The phased array wave spectrometer is a Ku-band real aperture radar that illuminates the sea surface at small incidence angles to receive sea surface echo power. It extracts three-dimensional sea surface information by removing radar-related factors like EIRP（Effective Isotropically Radiated Power）, antenna patterns, and system loss, which can be measured in a microwave anechoic chamber. However, the antenna pattern's precision is limited, leading to the 'concave' anomaly in the backscatter coefficient profile that hinders wave spectrum inversion. To address this, the paper uses particle swarm optimization to correct integral antenna gain. Validation with flight test data shows a 12% improvement in data reliability, supporting operational wave spectrum production.

Accurate prediction of ionospheric clutter is of great significance in improving the target detection performance of high-frequency surface wave radar. This paper proposes a short-term prediction model of ionospheric clutter using the Opposite Artificial Rabbits Optimization optimized Gated Recurrent Unit (OARO-GRU) network. Firstly, based on the a priori knowledge that ionospheric clutter received by high-frequency surface wave radar has chaotic characteristics, the input and output sample sets of the GRU network are constructed using the phase space reconstruction technique. Then, two improvement strategies, namely, the opposition-based learning and the Cauchy-based mutation, are incorporated to enhance the optimization capability of the original ARO, which is used to optimizthe GRU network with the values of three hyperparameters including the number of hidden layer nodes, the initial learning rate, and the maximum number of iterations. Finally, the optimized GRU network is retrained and fed into the test sample set for testing. The model is evaluated based on the given evaluation metrics. The experimental results show that compared with the other seven comparison forecast models, the proposed OARO-GRU network model has obvious superiority in prediction accuracy and reliability, and provides a new idea and method for effectively improving the target detection performance of high-frequency surface wave radar.