How many satellites must be received to...

Question 1 / 270706W73LwIW2jEsBhtrfcAV

Question 1 of 270706W73LwIW2jEsBhtrfcAV

How many satellites must be received to provide complete position and time?

Back

Question 1 of 27070

Q

How many satellites must be received to provide complete position and time?

🔍 Key Concepts

• GPS position fixing uses range measurements from satellites • Each satellite gives you a distance from a known point in space (like a sphere around your position) • To get a full 3D position (latitude, longitude, and altitude) plus time, more satellites are needed than for a 2D fix

💭 Think About

• How many unknowns are you solving for when you want latitude, longitude, altitude, and receiver clock error? • If each satellite gives you one equation (one distance), how many satellites do you need to solve for that many unknowns? • What is the difference in satellite requirement between a 2D position (assuming you know altitude) and a full 3D position with precise time?

✅ Before You Answer

• Count the number of unknowns (lat, lon, altitude, receiver clock error) you are solving for • Match that to the number of independent measurements (one from each satellite) you need • Remember that accurate time in GPS is not free; it is solved as an extra unknown in the navigation solution

Question 1 of 27070

Q

How many satellites must be received to provide complete position and time?

A

1

B

2

C

3

D

4

Question 1 / 270706W73LwIW2jEsBhtrfcAV

Question 1 of 270706W73LwIW2jEsBhtrfcAV

How many satellites must be received to provide complete position and time?

Back

Question 1 of 27070

Q

How many satellites must be received to provide complete position and time?

🔍 Key Concepts

• GPS position fixing uses range measurements from satellites • Each satellite gives you a distance from a known point in space (like a sphere around your position) • To get a full 3D position (latitude, longitude, and altitude) plus time, more satellites are needed than for a 2D fix

💭 Think About

• How many unknowns are you solving for when you want latitude, longitude, altitude, and receiver clock error? • If each satellite gives you one equation (one distance), how many satellites do you need to solve for that many unknowns? • What is the difference in satellite requirement between a 2D position (assuming you know altitude) and a full 3D position with precise time?

✅ Before You Answer

• Count the number of unknowns (lat, lon, altitude, receiver clock error) you are solving for • Match that to the number of independent measurements (one from each satellite) you need • Remember that accurate time in GPS is not free; it is solved as an extra unknown in the navigation solution