Geodesy Review Answers

Question 1

In GPS, distances are measured through satellites orbiting in nearly _______ orbits at nominal altitude of about _________.

Answer 1

a. circular, 21,038 km

Question 2

Ranges are measured with signals that are broadcast from the satellites to the gps receivers in the ________ part of the _________ spectrum.

Answer 2

b. microwave, electromagnetic

Question 3

The satellite can mark the moment the signal _______ and the receiver can mark the moment it _______.

Answer 3

c. departs, arrives

Question 4

From satellites codes are carried to GPS receivers by _____ waves. This waves has at least ______ characteristic such as phase, amplitude, or frequency that may change or modulate to carry information.

Answer 4

b. carrier, one

Question 5

Are freely available to the public. This code is a 1,023 bit long pseudo-random code broadcast at 1.023 MHz, repeating every millisecond.

Answer 5

a. Coarse / Acquisition code

Question 6

Reserved for military usage. This is a similar code broadcast at 10.23 MHz, but it repeats only once a week.

Answer 6

c. Restricted Precise code

Question 7

The P Code provides service for _____. Which is designed for higher positioning accuracy and was originally available only to users authorized by the department of defense.

Answer 7

d. Precise positioning service

Question 8

What are the GPS frequencies of L1and L2?

Answer 8

c. 1575.42 MHz and 1227.60 MHz

Question 9

The satellites are equipped with _______ clocks.

Answer 9

atomic

Question 10

Only needs one frequency standard because its electromagnetic wave travels to a retroprism and is reflected back to its origination

Answer 10

a. EDM ranging

Question 11

Broadcast signals from satellites are collected by the receiver, not reflected.

Answer 11

c. GPS ranging

Question 12

What is NAVSTAR GPS?

Answer 12

b. Navigation system with timing and ranging, global positioning system

Question 13

A method of electronic ranging using pulsed VHF(very-high-frequency) signals, was originally designed for bomber navigation, but was later adapted to more benign uses.

Answer 13

b. SHORAN

Question 14

By knitting together continental datum’s, ______ might be considered to be the first practical step toward positioning on a truly global scale.

Answer 14

HIRAN

Question 15

The first earth-orbiting satellite, made that possible.

Answer 15

SPUTNIK

Question 16

NASA’s first satellite tracking system. A ranging technique useful to GPS

Answer 16

PRIME MINITRACK

Question 17

The technique is that the recordings are encoded with time tags controlled by hydrogen masers, the most stable oscillators(clocks).

Answer 17

VLBI

Question 18

Its signal provides enough information to determine the exact moment of its closest approach to the earth.

Answer 18

DOPPLER SHIFT

Question 19

The first prototype satellite of the immediate precursor of the GPS system that was successfully launched reached orbit on June 29, 1961.

Answer 19

TRANSIT

Question 20

TRANSIT satellites used the frequencies of ______ and ______, while GPS uses 1575.42 MHz and 1227.60 MHz.

Answer 20

400 MHz and 150 MHz

Question 21

GPS needed at least ______ satellite above an observer’s horizon for adequate positioning, it has to be satisfied at all times anywhere on or near the earth.

Answer 21

Four

Question 22

The ________ allowed the GPS receiver to acquire signals from several satellites simultaneously and still distinguish them from one another.

Answer 22

PRN Codes

Question 23

When an observer actually performs a GPS survey project, one of the most noticeable aspects of a satellite’s motion is that it returns to the same position in the sky about _____________ each day.

Answer 23

4 minutes earlier

Question 24

The satellite actually ________________ with each successive solar day.

Answer 24

lose 3 minutes and 56 seconds

Question 25

The accuracy of a GPS position is subject to a geometric phenomenon called dilution of precision(DOP). A low DOP factor is _____, a high DOP factor is _____.

Answer 25

good, bad

Question 26

11 GPS satellites launched from Vanderberg Air Force between 1978 and 1985 were known _______.

Answer 26

BLOCK I satellites