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B-4
Glossary
only uses one burst in 26. When the FACCH steals control from
the TCH small drop-outs in the speech can often be heard.
Frame A repetitive collection of time slots in a TDMA system.
GMSK Gaussian Filtered Minimum Shift Keying. The type of digital
modulation used for the GSM system.
GSM900 Global System for Mobile Communication. GSM900 is the
original GSM system, using frequencies in the 900 MHz band,
and is designed for wide area cellular operation.
Global Phase
Error
An in-channel test of modulation quality for GSM transmitters
using a constant amplitude envelope when transmitting
information. Global phase measures the difference between the
measured phase trajectory and the ideal phase trajectory.
Guard Bits These bits provide a buffer between adjacent data packets.
There are ramp-up and ramp-down guard bits.
IMSI International Mobile Subscriber Identification. A unique
subscriber number which is contained on the SIM card.
MSK Minimum Shift Keying. A form of digital modulation in which
a frequency shift is chosen to exactly twice the data bit rate. It is
called minimum shift keying because the frequency spacing
between the two frequency states is the minimum spacing that
allows the two frequency states to be orthogonal to each other.
PCS1900 Personal Communications System. This is a system used in the
USA, bands have been released around 1.9 GHz.
PRBS Pseudo-Random Bit Sequence. A pattern of bits used in bit
error testing.
Pulsed RF
Power
An in-channel, test of the mobile phone’s ability to correctly
turn its transmitter on and off.
RACH RACH (Random Access Channel) is used to grab the attention
of the BS. RACH is a special short burst used to inform the
mobile of its timing advance. These bursts are short to avoid
collisions with other timeslots.