The global positioning system (GPS) must be familiar to every user of a smartphone as a way to locate one’s position on Earth to within several meters. The constellation of orbiting atomic clocks equipped with radio transmitters allows receivers on Earth to determine their own position by measuring the travel times of radio signals from multiple satellites. A physics laboratory for an upper-level majors course involving GPS signals might be assumed to focus on relativistic effects (either special or general), but this paper demonstrates that the ultra-precise time signal from a GPS receiver can be used for a variety of data collection purposes.
References
1.
Brian
Patterson
et al., “An undergraduate demonstration of gravitational time dilation
,” Phys. Teach.
58
, 268
–270
(2020
).2.
M. Shane
Burns
et al., “Measurement of gravitational time dilation: An undergraduate research project
,” Am. J. Phys.
85
, 757
(2017
).3.
Digilent BASYS 3
, under $120 after academic discount
(https://store.digilentinc.com/basys-3-artix-7-fpga-trainer-board-recommended-for-introductory-users/).4.
Source files associated with this project
can be found at https://sites.google.com/georgiasouthern.edu/wbaird/home/fpga-clock.5.
“Dielectric Constant,”
https://omnexus.specialchem.com/polymer-properties/properties/dielectric-constant.6.
Robert H.
Cole
, “Time domain reflectometry
,” Ann. Rev. Phys. Chem.
28
, 283
–300
(1977
).7.
F.
Fontanelli
, L.
Repetto
, and R.
Chittofrati
, “A simple instrument for measuring time intervals with subnanosecond resolution
,” Am. J. Phys.
70
, 1234
–1236
(2002
).8.
Y.
Fujiyasu
, C. E.
Pierce
, L.
Fan
, and C. P.
Wong
, “High dielectric insulation coating for time domain reflectometry soil moisture sensor
,” Water Resour. Res.
40
, W04602
(2004
).9.
Jean Carlos
Hernandez-Meija
, “Time Domain Reflectometry (TDR
),” in Cable Diagnostic Focused Initiative Handbook
(https://www.neetrac.gatech.edu/cdfi-publications.html) is a good source of general background information.10.
William H.
Baird
, “Measuring the balance of the world’s largest machine
,” Am. J. Phys.
89
, 1086
(2021
).11.
William
Baird
, Jeffery
Secrest
, Clifford
Padgett
, Wayne
Johnson
, and Claire
Hagrelius
, “Smartphones and time zones
,” Phys. Teach.
54
, 351
–353
(2016
).© 2022 Author(s). Published under an exclusive license by American Association of Physics Teachers.
2022
Author(s)
AAPT members receive access to The Physics Teacher and the American Journal of Physics as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.