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The precision of satellite positioning system depends largely on the numbers and geometric layout of the positioning satellite, the GDOP is one of the important parameters to measure the geometric layout of positioning satellites. From the perspective of GDOP, the relation between a different pseudo-satellite location and layout for the accuracy of the positioning system has been studied. For the positioning of the four pseudo-satellites, the simulation analysis of the relationship of the GDOP parameter changes with the pseudo-satellite longitude, latitude and location of the user. Studies have shown that different latitudes, the symmetrical distribution of the pseudo-satellite layout has good geometric accuracy; the same layout, the low-latitude, GDOP is less than the high-latitude; when the user moves in the regional variation in the geometric center of the pseudo-satellite layout, the GDOP values did not change and less than the value of the central region; at the same time, increasing the number of pseudo-satellite can reduce the GDOP value.

ESPAC method is a rapidly emerging field of seismological research, which can reflect the physical properties of the Earth’s medium. In the process of using the ESPAC method, sometimes the noise of the original data is relatively large, and the raw data of each seismometer needs to be preprocessed, including operations such as de-averaging, de-trending, re-sampling, normalization, and filtering. The selection of the normalized method and the selection of the bandwidth of the filter are particularly important, and it will produce the wrong result if not handled properly. This article attempts to use the extended spatial autocorrelation (ESPAC) method to extract Rayleigh-wave phase velocity dispersion curves from the vertical component of the seismic stations’ microtremors, and proposes feasible and effective solutions to the selection of the normalized method and bandwidth of bandpass filtering.

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Time jitter is an important means for evaluating the performance of high-speed communication systems. Current high-speed digital designs require faster edge speeds and smaller effective data windows. Therefore, analysis of the root cause of jitter has become the key factor in determining the success or failure of a design. To analyze the jitter source of the whole link, the jitter is usually extracted and analyzed by software or hardware at the receivers. To verify the accuracy of jitter extraction at the receivers, many instrument manufacturing companies have developed oscilloscope software to inject jitter at the transmitters, but the core algorithms for jitter generation are commercially sensitive and the software cannot inject all types of jitter, particularly bounded uncorrelated jitter, into the pure signals. This paper proposes a software jitter modeling and injection algorithm that can be implemented in MATLAB and includes transmitter test signal modeling, jitter generation, and the injection of various types of jitter. Unlike other research and commercial software, the proposed algorithm enables the injection of various types of jitter, notably bounded uncorrelated jitter, into test signals. This algorithm is suitable for integration into real-time oscilloscopes for jitter generation and injection.