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20 Cards in this Set
- Front
- Back
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GPS signals are in the _________ part of the electromagnetic spectrum.
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microwave
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Satellites move at about ___km/sec or ______km/hr.
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4, 14400
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What are the 4 types of information that a GPS signal contains?
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- time on the satellite at transmission time
- instantaneous position - information on atmospheric corrections - satellite ID info |
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Codes are carried to receivers by _________ waves.
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carrier
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The L-Band ranges in frequency from _____MHz to _____MHz.
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390, 1550
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What are the three primary frequencies used by GPS signals?
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L1 - 1575.42 MHz
L2 - 1227.60 MHz L5 - 1176.45 MHz |
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What are 3 code types used by GPS signals?
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- Navigation code
- P Code - C/A Code |
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What information is contained within the navigation message of Navigation Code?
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- Clock corrections
- Ephemeris Data - Atmospheric corrections - satellite almanac - satellite health |
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What is a Julian Date?
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- a number that represents the day counted from Jan. 1
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How does GPS Time differ from UTC time?
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UTC uses leap seconds, unlike GPS time.
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What are some differences with P Code and C/A Code?
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- P code is on both L1 and L2; C/A uses only L1
- P code is much faster and more precise - P code repeats once per week; C/A code repeats once per millisecon - each satellite broadcasts an assigned portion of P code; C/A is broadcast with its own unique code |
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GPS satellites orbit the earth at approximately what altitude?
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20,000 km
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What are the 3 segments of GPS?
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Space
Control User |
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How many satellites are fully operational? How many orbital planes are there and what is the angle to the equator?
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31, four, 55 degrees
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What is DOP? When is DOP good or bad?
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Dilution of Precision - concerns the geometric strength of the figure connecting the visible satellites and the receiver. Bad DOP occurs when all the satellites are crowded together in one part of the sky, resulting in a high DOP - which is bad. The larger the volume of the body defined by the lines from the receiver to the satellites, the better.
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What is the Control Segment?
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- The U.S Dept of Defence's network of GPS monitoring and upload stations around the world.
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Where is the Master Control Station located?
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Schriver Air Force Base - near Colorado Springs, CO
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What do the monitoring stations keep track of? What information do they provide to the MCS?
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Navigation signals of all satellites. They provide meteorlogical, pseudorange, and carrier phase data.
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What information does the MCS provide?
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- broadcast ephemeris
- satellite clock |
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What is the User Segment?
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- component of the GPS system that includes the user equipment, applications, and operational procedures.
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