ET Vol 5 Navigation systems Flashcards by jamerion shorter

Tactical navigation is directly concerned with maneuvering the ship in navigable waters.

false

How well did you know this?

Not at all

Perfectly

Estimating ship’s position between known navigational points or fixes is known as

dead reckoning

How well did you know this?

Not at all

Perfectly

Radio navigation consists of which of the following categories?

Sub-space systems (SATNAV, TRANSIT, NAVSTAR) 2. Space–based systems (omega, loran)

How well did you know this?

Not at all

Perfectly

One of the characteristics of dead reckoning is that the accuracy of the estimated position never exceeds the navigation method used to obtain the last fix. What happens to the accuracy of the estimated position over time?

It fluctuates

How well did you know this?

Not at all

Perfectly

Referring to landmarks with known positions on earth describes which one of the following navigation methods?

piloting

How well did you know this?

Not at all

Perfectly

Which of the following actions required to determine position in piloting is/are not required in electronic navigation?

Seeing the landmarks

How well did you know this?

Not at all

Perfectly

According to the 1992 Federal Radio Navigation Plan, which of the following systems will become the primary reference navigation system for surface ships?

NAVSTAR(GPS)

How well did you know this?

Not at all

Perfectly

what is LORAN

Long Range Aid to NAvigation

How well did you know this?

Not at all

Perfectly

What is omega

VLF radio NAvigation

How well did you know this?

Not at all

Perfectly

LORAN takes advantage of what radio signal characteristic?

Constant velocity

How well did you know this?

Not at all

Perfectly

OMEGA is a hyperbolic phase— difference measuring system that compares the phase angle of two or more radio signals synchronized to what device or factor?

A common time base

How well did you know this?

Not at all

Perfectly

Which navigation system continually computes the latitude and longitude of a ship by sensing acceleration?

SINS (Ships inertial navigation system)

How well did you know this?

Not at all

Perfectly

A ship’s inertial navigation system is dependent on celestial, sight, and radio navigation aids.

false

How well did you know this?

Not at all

Perfectly

What device measures changes in speed or direction along the axis in which it lies?

Accelerometer

How well did you know this?

Not at all

Perfectly

What type of system is used to keep a SINS platform stabilized?

Gyro

How well did you know this?

Not at all

Perfectly

Which of the following is a standalone SINS?

AN/WSN-5

How well did you know this?

Not at all

Perfectly

Approximately how often can operators using the NNSS obtain fixes?

Every 2 hours

How well did you know this?

Not at all

Perfectly

NNSS satellites transmit phase modulated data every 2 minutes on how many rf carriers?

How well did you know this?

Not at all

Perfectly

What are the two types of NNSS satellite parameters included in the phase-modulated data?

Fixed and variable

How well did you know this?

Not at all

Perfectly

The nominal orbit of NNSS satellites is what type of orbital parameter?

fixed

How well did you know this?

Not at all

Perfectly

NNSS satellite data can be used as an accurate time reference.

true

How well did you know this?

Not at all

Perfectly

NNSS satellite refined orbits are calculated at which of the following facilities?

Tracking station

How well did you know this?

Not at all

Perfectly

Which of the following facilities calculates NNSS satellite clock error before satellite message injection?

Control center

How well did you know this?

Not at all

Perfectly

Approximately how long does it take the injection station to transmit information to an NNSS satellite?

15 seconds

How well did you know this?

Not at all

Perfectly

If errors are detected during a readback of freshly injected satellite data, how often is NNSS satellite message injection repeated until the transmission is verified as being correct?

every 2 minutes

At what point during the satellite pass will expansion effects cause the received frequencies to drop below the generated frequencies?

T3- Leaving away from

At what point will the received frequencies exactly match the transmitted frequencies?

T2-EVEN

At what point will compression effects cause the received frequencies to be higher than the transmitted frequencies?

T1- Approaching Fast

Which of the following factors affects the measurement of Doppler shift?

Refraction

Satellites broadcast at what to freqs to fix refraction?

150 and 400 MHZ

To solve the problem of Doppler shift accuracy, satellites are designed to transmit on how many frequencies?

Accurate NNSS position fixes for a moving vessel require what additional computation?

vessels speed

Which ship’s system will provide the information required to perform the additional computation required by NNSS?

SINS

Given the orbital parameters of a satellite, the Doppler shift of the signal transmitted from that satellite, and the velocity of a vessel, it is possible to obtain a navigational fix if the satellite is within what distance from the navigation set?

LOS Line-of-Sight

One of the capabilities of the AN/WRN-5 includes time-ordered alerts for up to how many satellites?

What is the “at sea” accuracy of the AN/SRN-19(V)2?

.25 miles

What activity may degrade the accuracy of the AN/SRN-19(V)2?

sunspots

You are initializing the AN/SRN– 19(V)2. In addition to programing the set’s position, what other parameter must you enter?

antenna length

What navigational system will replace the NNSS?

NAVSTAR GPS

Which of the following terms describe GPS satellite positioning data?

Almanac (data for ground satellites) and ephemeris (position data for single satellite)

How often is the GPS satellite navigation data message updated?

every 24 hours

What facility transmits the data required to update the GPS satellite navigation data message?

Manned Control Center

There are how many (a) active spare and (b) active operational GPS satellites?

(a) 21 (b) 3

How many earth orbits will each GPS satellite complete in a 24–hour period

What communications technique is used for GPS satellite broadcasts?

Spread–spectrum

What are the to Spread-Spectrum Rf Freqs?

1575.42 MHz (L1-RF) 1227.60 MHz (L2-RF)

GPS satellites are positioned so a minimum of how many satellites are observable to a user anywhere on earth?

Which of the two codes (C/A and P) transmitted by GPS satellites is NOT available to civilian users?

Precise code (only Military)

Which of the following data is NOT included in the GPS NAV–msg?

Spectral

GPS navigation is based on what principle?

Satellite ranging (measure time from Satellite to NAVSET divide travel time by speed of light

Within how many feet can GPS determine position fixes?

50ft

To obtain the above accuracy, how many satellite inputs are required

How is the time difference between satellite transmission and when the navigation set receives this signal related to the distance between the satellite and the receiver?

Directly proportional

GPS satellites use atomic clocks; the receivers do not. What type of error must be computed based on this fact?

Clock

Tropospheric delay is predicted and included in what satellite data?

Almanac

Ionospheric delay is greatest when a signal is received from directly overhead.

false (near the horizon)

Of the frequencies listed below, which one will ionospheric delay phase–shift the most?

1227.60 MHz L2

Satellite signals reflecting off one or more objects before reaching the navigation set produce what type of reception?

Multipath-reached it different times

What data do operators enter into the AN/WRN-6(V) to speed up satellite acquisition?

Time and date Current position

Which of the following is the normal operating mode of the AN/WRN-6(V)?

Navigation

Which of the following is a portable GPS receiver?

AN/PSN–8

TACAN is based on what type of radio air-navigation system?

Polar-coordinate

Instead of depending on radio-wave reflection, beacon-transponders generate what type of replies?

Artificial

What type of decoders do TACAN transponders use?

Twin–pulse

Which of the following receiver controls provides noise–generated output?

Squitter

If more interrogating aircraft come into the TACAN’S range, the number of noise–generated pulses will

decrease

What signal does the TACAN ground station transmit to identify itself?

Identification pulse group

What characteristic of the transmitted TACAN pulses supplies the distance information to aircraft?

Timing

What type of modulation is used to convey TACAN bearing information?

bearing

What type of radiation pattern is transmitted by the TACAN ground station antenna?

cardioid

What is the common name of the 135–Hz reference burst?

Auxiliary reference burst

How often is the identification code broadcast?

Every 37.5 minutes

What is the designation of latest TACAN equipment in the fleet?

URN-25

In the AS–3240 electronically– scanned antenna, the old singlephase rotating parasitic element has been replaced by how many electronically–switched inner parasitic elements?

What is one big advantage the electronically–scanned antenna has over the old mechanically–rotated antenna?

It eliminates bandwidth limitations

The AN/URN-20 uses the same electronically-scanned antenna as the AN/URN-25.

true

What is the total number of TACAN channels available using both X and Y modes?

252 (126 for X) (126 for Y)

The TACAN receiver frequency is always displaced how many MHz from the transmitter frequency?

How many aircraft can be provided distance data simultaneously?

100