Study of the GNSS Jamming in Real Environment

GNSS systems are susceptible to radio interferencedespite then operating in a spread spectrum. The commercejammers power up to 2 watts that can block the receiver functionat 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 simulatorfor generation of the satellite signals and a vector signal RFgenerator for generating different types of interference signals.The second software radio method is based on a software GNSSsimulator and a signal processing in Matlab. The receivers weretested for narrowband CW interference, FM modulated signaland chirp jamming signals, and scenarios. The signal to noiseratio usually drops down to 27 dBc-Hz while the jamming tosignal ratio is different for different types of interference. Thechirp signal is very effective.The jammer signal is well propagated in free space while inthe real mobile urban and suburban environment it is usuallystrongly attenuated

Digital Up and Down Converter for High Performance VHF and UHF transceiver

The Digital Up and Down Converter (DUC/DDC) is a basic building part of the professional digital mobile transceiver. The paper presents DDC/DDS for dual mode professional VHF/UHF transceiver developed for railway radio. The transceiver complies ETSI standards for NFM and Digital Mobile Radio (DMR). The DUC/DDC is featured with the channel selectivity exceeding 70 dB and dynamic range more than 90 dB. The implementation of the other standards that use constant envelope modulation like small satellite UHF communication links is also possible

Digital Up and Down Converter for High Performance VHF and UHF transceiver

The Digital Up and Down Converter (DUC/DDC) is a basic building part of the professional digital mobile transceiver. The paper presents DDC/DDS for dual mode professional VHF/UHF transceiver developed for railway radio. The transceiver complies ETSI standards for NFM and Digital Mobile Radio (DMR). The DUC/DDC is featured with the channel selectivity exceeding 70 dB and dynamic range more than 90 dB. The implementation of the other standards that use constant envelope modulation like small satellite UHF communication links is also possible