GNSS Flashcards

1
Q

What is GNSS and what does it encompass?

A

Global Navigation Satelite System:

GPS - US Based
Galileo - EU
BeiDou - China

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2
Q

A GPS position is based on:

A

Measuring the time and distance from the satellites to the receiver to establish a position

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3
Q

How many satelites are needed to get a two dimensional position (like lat and long)?

A
  1. You need 4 satellites for a 3D (lat, long, altitude) position
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4
Q

Why do you need 3 satellites to get a 2D position?

A

Trillateration

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5
Q

What advantages does GPS have over ADF or VOR?

A
  • Point to Point navigation
  • Unlimited range
  • Not affected by weather
  • Very accurate (to as little as 1 meter)
  • Very cheap
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6
Q

What are the pitfalls of GPS?

A

A user-made waypoint could have been entered incorrectly, leading you to the wrong place

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7
Q

When was GPS originally designed?

A

In the US by the Department of Defence

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8
Q

GNSS horizontal and verticle positions are accurate to:

A

6 and 8 meters respectively 95% of the time

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9
Q

What two frequencies does the GNSS system transmit on continuously?

A

1227.6 and 1575.42 Mhz

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10
Q

GPS is line of sight, what problems can that create?

A

Signal masking/blocking can be an issue.

This can occure when there is mountainous terrain, man-made structures, or a poorly located antenna on the AC.

Still tho GSP coverage is way better than anythign else we have

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11
Q

How many atomic clocks are on board each satallite?

A

4, with a guaranteed accuracy down to 1 nanosecond (1 billionth of a second)

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12
Q

GPS accuracy is dependent on the relative position (the geometry) of the _____

A

Satellite

The further apart the satellites are from one another, the more accurate your position will be

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13
Q

What is differential GPS?

A

A GPS that uses differential techniques to achieve better accuracy.

This is done by locating a receiver on the ground at a precisely surveyed position

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14
Q

What are the two types of differential GPSs?

A

WAAS - Wide Area Augmentation System

LAAS - Local Area Augmentation System

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15
Q

What is LAAS?

A

An all-weather aircraft landing system based on real-time differential correction of the GPS signal

We dont have it in Canada

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16
Q

What is RAIM?

A

A warning system? Works by comparing position solutions using different combinations of satellites

  • Requires at least 5 satellites
  • Baro-Aiding RAIM: At least 4
  • FDE (Advanced RAIM): At least 6
17
Q

Which GSP is approved for primary nav use in IFR ops?

A

TSO C-129

18
Q

Your track over the ground as shown by your GPS will not be the same as your heading because…

A

It doesn’t account for wind correction. In a no wind situation, your GPS track and heading would be the same.

19
Q

Basic GPS terms

A