Sokkia GSR2700 ISX, Operation Manual

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Glossary
84 GSR2700 ISX Operations Manual
GSM—
Global System for Mobile Communications. A digital cellular
phone technology based on TDMA. First introduced in 1991, the GSM
standard has been deployed at three different frequency bands: 900
MHz, 1800 MHz, and 1900 MHz. GSM uses narrowband TDMA,
which allows eight simultaneous calls on the same radio frequency.
I
Integer ambiguity/bias—
See Ambiguity .
Integrated Doppler—
See Carrier phase .
Ionosphere—
The layers of ionized air in the atmosphere extending
from 70 kilometers to 700 kilometers and higher. Depending on
frequency, the ionosphere can either block radio signals completely or
change the propagation speed. GPS/GNSS signals penetrate the
ionosphere but are delayed. This delay induces error in the GPS/
GNSS measurements that can result in poor survey results. Most
GPS/GNSS receivers and processing software model the ionosphere
to minimize its affects. Also, the effects of ionosphere can be nearly
eliminated by using dual frequency receivers which can calculate the
delay due to ionosphere.
L
L1—
The 1575.42 MHz GPS carrier frequency, which contains the
coarse acquisition (C/A) code, as well as encrypted P-code and
navigation messages used by commercial GPS receivers.
L2—
A secondary GPS carrier (at 1227.60 MHz) that presently
contains only the encrypted P-code. A C/A code will be available on
the L2 frequency in the future.
L-Band—
The range of radio frequencies that includes the GPS L1
and L2 carrier frequencies and the OmniSTAR satellite signals.
M
Mask angle—
See Elevation mask angle .