A higher-load-reflects-a-positive-step ledger shows that a load above the line impedance sends back a same-sign voltage echo. The 12 ohm load against a 4 ohm line gives Gamma = 1/2, so the stated 12 V incident step reflects as +6 V only inside the ideal lossless-line model. Real lines add loss, dispersion, connector discontinuities, source impedance, finite rise time, calibration limits, finite precision, and measurement uncertainty.
A load above the line impedance returns a same-sign reflected step. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
A higher load gives a positive coefficient
The load is 12 ohms and the line is 4 ohms, so the coefficient is 1 over 2.
Γ=12+412−4=21
The reflected step has the same sign
Half of the 12 volt incident step reflects as 6 volts.