The other problem with satellites is latency (the time it takes the signal to move from point A to point B). Telecom satellites orbit 26,000 miles above the equator, so the minimum time for the round trip will be ~0.3 seconds but much longer at higher latitudes. Using cables it’s usually less than 0.025 seconds.
Do both signals move at the theoretical speed of light, or are they limited by air/cable friction factors?