B. What is the difference between TETRA and Tetrapol?
TETRA is an open standard defined by ETSI (European Telecommunications Standards Institute), while Tetrapol is a standard established and first employed by Matra-Nortel Communications. Both have a similar range of applications: TETRA focuses more on PAMR systems, while Tetrapol specialises in PMR. Although the names are quite similar, the technologies are very different: TETRA applies a modulation format called pi/4 DQPSK, TDMA with 4 channels per carrier, and carrier spacing of 25 kHz. In contrast, Tetrapol uses GMSK, FDMA, and channels are typically separated by 12.5 kHz. The protocols are also different. Both TETRA and Tetrapol support fast call set-up times, data transmission (at different rates), and encryption.
