Link Budget Equation (Friis Equation Solver)

A TI-84 Plus CE program that solves the Friis transmission equation for any unknown variable. Built using the TI-84 Plus CE C/C++ Toolchain.

Equation

Pr = Pt + Gt + Gr + 20*log10(λ / (4πd))

Variable	Description	Unit
Pr	Received power	dBm
Pt	Transmit power	dBm
Gt	Transmit antenna gain	dBi
Gr	Receive antenna gain	dBi
d	Distance between antennas	meters
f	Frequency (used to compute λ = c/f)	MHz

How to Use

1. Transfer bin/FRIIS.8xp to the calculator using TI Connect CE.
2. Run the program from the homescreen: prgmFRIIS
3. The main menu shows six solvable variables. Press 1-6 to choose which to solve for.
4. Enter the five known values when prompted. Press ENTER after each value. Use the (-) key for negative numbers.
5. The result is displayed along with a summary of all inputs. Press any key to return to the menu.
6. Press CLEAR on the menu to exit the program. Pressing CLEAR during input returns to the menu.

Building

Requires the CE C/C++ Toolchain (cedev-config must be on PATH).

make          # builds bin/FRIIS.8xp
make clean    # removes build artifacts

References

• Friis transmission equation (Wikipedia)
• CE Toolchain documentation