User's Manual

SPSx50 Modular GPS Receiver User Guide 163
Glossary
This section explains some of the terms used in this manual.
almanac A file that contains orbit information on all the satellites, clock corrections, and
atmospheric delay parameters. The almanac is transmitted by a GPS satellite to a GPS
receiver, where it facilitates rapid acquisition of GPS signals when you start collecting
data, or when you have lost track of satellites and are trying to regain GPS signals.
The orbit information is a subset of the emphemeris / ephemerides data.
AutoBase AutoBase uses the position of the receiver to automatically select the correct base
station; allowing for one button press operation of a base station. It shortens setup
time associated with repeated daily base station setups at the same location on
jobsites.
base station Also called reference station.
A base station is a GPS antenna and receiver positioned on a known location
specifically to collect data for differential correction Base data needs to be collected
at the same time as you collect data on a rover unit. A base station can be a permanent
station that collects base data for provision to multiple users, or a rover unit that you
locate on known coordinates for the duration of the datalogging session.
Binary exchange
format
See BINEX.
BINEX (BInary EXchange format)
BINEX is an operational binary format standard for GPS/GLONASS/SBAS research
purposes. It has been designed to grow and allow encapsulation of all (or most) of the
information currently allowed for in a range of other formats.
broadcast server An Internet server that manages authentication and password control for a network of
VRS servers, and relays VRS corrections from the VRS server that you select.
carrier A radio wave having at least one characteristic (such as frequency, amplitude, or phase)
that can be varied from a known reference value by modulation.
carrier frequency The frequency of the unmodulated fundamental output of a radio transmitter. The GPS
L1 carrier frequency is 1575.42 MHz.
carrier phase The difference between the carrier signal generated by the internal oscillator of a
receiver and the carrier signal coming in from the satellite.
carrier phase The time taken for the L1 or L2 carrier signal generated by the satellite to reach the
GPS receiver. Measuring the number of carrier waves between the satellite and receiver
is a very accurate method of calculating the distance between them.
cellular modems A wireless adapter that connects a laptop computer to a cellular telephone system for
data transfer. Cellular modems, which contain their own antennas, plug into a PC Card
slot or into the USB port of the computer and are available for a variety of wireless data
services such as GPRS.
CMR (Compact Measurement Record)
A real-time message format developed by Trimble for broadcasting corrections to
other Trimble receivers. CMR is a more efficient alternative to RTCM.
covanance The mean value.