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Methods to improve interference immunity of tonal track circuits

100%

Honcharov K. , Rybalka R.

Archives of Transport System Telematics

2013

tom Vol. 6, iss. 1

9--13

One of the ways to improve track circuits is associated with transfer of equipment to modern microelectronic element base and with using new more advanced signal processing techniques. In paper the various methods to improve interference immunity of tonal track circuits have been considered. It was proposed instead of periodic amplitude shift keying signals use the phase shift keying signals with six-bit Hamming code. This will allow to expand the number of selective marks and to increase the information redundancy of signal. As a result, the probability of correct detection of such signal under influence of interferences will increase. The expedience of using the correlation demodulation with receiving code combination by symbols also has been shown. The efficiency of proposed methods is confirmed by the results of simulation.

Study of the GNSS Jamming in Real Environment

100%

Morong T. , Puričer P. , Kovář P.

International Journal of Electronics and Telecommunications

2019

tom Vol. 65, No. 1

65--70

GNSS systems are susceptible to radio interference despite then operating in a spread spectrum. The commerce jammers power up to 2 watts that can block the receiver function at a distance of up to 15 kilometers in free space. Two original methods for GNSS receiver testing were developed. The first method is based on the usage of a GNSS simulator for generation of the satellite signals and a vector signal RF generator for generating different types of interference signals. The second software radio method is based on a software GNSS simulator and a signal processing in Matlab. The receivers were tested for narrowband CW interference, FM modulated signal and chirp jamming signals, and scenarios. The signal to noise ratio usually drops down to 27 dBc-Hz while the jamming to signal ratio is different for different types of interference. The chirp signal is very effective. The jammer signal is well propagated in free space while in the real mobile urban and suburban environment it is usually strongly attenuated.