DIGITAL SIMULATOR OF GPS C/A SIGNALS

A structure of a digital signal simulator which allows generating testing GPS C/A signals or creating signal-like interference is observed. Proposed scheme of the simulator includes generators of navigation signals, a generator of noiselike signal, a signal summation block and a block of signal bit capacity transformation. A vari-ant of simulator hardware implementation in FPGA is showed. Examples of gener-ated signals are presented.

Creation of a Hardware-Software Dynamic Signal Simulator of the Upgraded Inter-Satellite Radio Link of the GLONASS System

This work is aimed at creating a hardware-software signal simulator of the upgraded inter-satellite radio link (ISRL) of the GLONASS system. The simulator shapes ISRL signals with dynamically changing parameters of the Doppler frequency shift and delay, which correspond to the mutual dynamics of spacecraft (SC) motion of the GLONASS system. The upgraded inter-satellite radio link will provide (as compared to the current ISRL) an increase in the information transfer rate of up to four times, as well as boost the accuracy of measuring the distance between satellites by two times. Modernization consists in complementing the radio signal of the second orthogonal (phase-shifted carrier frequency by 90 degrees relative to the existing one) component. To modernize the ISRL, it is necessary to create and verify new equipment for receiving and transmitting signals of the upgraded ISRL of the GLONASS system. The simulator is designed to process measurement algorithms embedded in the on-board equipment for inter-satellite measurements and assess their consistency. Consistency evaluation consists in measuring and analyzing the difference between the Doppler parameters and delay introduced into the signal and the estimation of these parameters in the receiving equipment of the ISRL. This difference will be the measurement error. Dynamic simulation is performed for 24 system points, corresponding to GLONASS satellites, on the half-period of satellite revolution (20 280 seconds). The signal is generated at the input of the antenna-feeder device of one of the satellites in accordance with the information for generating the measuring signal, parameters of the transmitters of the signals of the upgraded ISRL and the almanac of the satellite constellation (because the signal at the input of the antenna-feeder device of the navigation receiver incomes from several SC) specified by the user.

Design of Electrocardiograph Signal Simulator

Medical equipment functional test and calibration is a routine activity that must be carried on periodically. Electrocardiograph (ECG) requires an ECG phantom to calibrate the function. This calibrator is commonly called ECG signal simulator. The purpose of this study is to design a simple ECG signal simulator with ten leads of signals that can be used to test ECG recorders with standard recording procedures. With the ECG signal simulator that was designed and made, the development of signal patterns can be made as needed. The normal human cardiac signal displayed on the ECGSIM software. The potential value that displayed on ECGSIM software can be extracted manually and assembled as a flash program of microcontroller, so this microcontroller will generate some digital code by each parallel port. This digital code then converted as an analog signal by DAC. The electrocardiograph signal simulator output is an analog signal that identical with each lead according to the recording method of bipolar, unipolar and precordial of ECG. This analog signal was tested using a standard ECG recorder. It is proved that the simulator is able to generate an electrical signal in accordance with the characteristics of the human cardiac signal displayed on ECGSIM software. The results of human electrocardiograph signal simulator design are a device that generates electrical signals with output specifications that correspond to the bioelectric signals of the human heart. The statistical test showed that the p-value is more than 0.05. It is mean that there is no significant difference between the design and standard. The signals pattern has met the specification of ECGSIM signal