среда, 3 февраля 2010 г.

Signals. PSK: Tetra

Professional digital trunking system, pi/4 DQPSK

Author: SergUA6
Band Width ~ 22000 Hz
Low Range ~ 2000 Hz, shift is possible, acception in SSB
Baud Rate 18000 Hz
n-Ary (PSK/MPSK) PSK-8, pi/4 DQPSK
Carrier frequency ~ 13242 Hz, shift is possible, acception in SSB
ACF ~56-57 and 14 ms
RX mode SSB

pic.1 Generall view
pic.2 the signal in 4th exponantion
pic.3 the signal in 8th exponantion
pic.4 manipulation speed
pic.5 Phase constellation
pic.5 ACF after PSK demodulator

TETRA - is the standard called to replace analogue systems of type PMR on VHF range. It was established approximately in 1995. From the point of view of a signal, it is easily enough recognised under the basic characteristics, such are speed of manipulation 18000 Hz and individual ACF. It is necessary to notice that, despite wide enough prevalence, there are almost no good records of this type of signals, because relvatively wideband strips IF and AF bands are required, altought we have two records with this signal, with good quality.