GPS Lab Worksheet | GPS Workshop

✅ Experiment 1: Device Validation

Verify that your GPS unit is working correctly before collecting detailed data.

Validation Checklist

Check	Expected Result	Your Result	Pass?
Satellites detected	4 or more
Valid coordinates	Lat/Long displayed (not "INVALID")
Google Maps verification	Pin within 10-20m of location
HDOP value	Less than 5

Recorded Coordinates

Latitude:
Longitude:
Time of reading:

Did the Google Maps pin match your actual location? Describe any discrepancy:

📏 Experiment 2: Distance Measurement

Compare GPS-calculated distance to a known paced distance.

Position Data

Measurement	Position A (Start)	Position B (End)
Latitude
Longitude
Satellites
HDOP

Distance Calculations

Step Count:	_______ steps
Paced Distance (steps × ~1m):	_______ meters
GPS-Calculated Distance:	_______ meters

Use: sounny.github.io/latlongdist to calculate GPS distance

Error Analysis

Difference (Error):	_______ meters
Percentage Error:	_______ %

Percentage Error = |GPS Distance - Paced Distance| / Paced Distance × 100

Is your error within the expected range (20-30m)? What factors may have contributed to error?

🌍 Experiment 3: Calculate Earth's Circumference

Recreate Eratosthenes' famous experiment using GPS!

Data from Experiment 2

Latitude A:
Latitude B:
Distance walked:	_______ meters

Calculations

Angular Difference = |Latitude B - Latitude A| = _______ degrees

Circumference = (Distance / Angular Difference) × 360 = _______ km

Show Your Work

Comparison to Actual Value

Your Calculated Circumference:	_______ km
Actual Earth Circumference:	40,075 km
Your Error:	_______ km (_______ %)

📝 Discussion Questions

1. How close did your circumference calculation come to the actual value? What sources of error affected your result?

2. How could you improve the accuracy of this experiment?

3. Why did Eratosthenes need the sun, while you could use GPS?

4. How many satellites did you typically see? Did this vary by location?

5. Did the environment (buildings, trees, indoors) affect your GPS results? Explain.

📍 Additional Waypoint Data Collection

Record GPS data from 3-5 locations around campus:

#	Location Description	Latitude	Longitude	Altitude (m)	Sats	HDOP
1
2
3
4
5

Observations

What patterns did you notice in satellite count and HDOP across different locations?

📡 GPS Workshop Lab Worksheet