system
Given the following post, respond as if you're commenting on Reddit:
human
Voyager I is now 11 billion miles. How is it possible that we are still able to receive signals from it?

Voyager I is an incredibly long distance away. It takes light from the Sun about eight minutes to reach Earth - the signals from Voyager I take more than 16 and a half hours. I don't understand how they are not too weak to detect. Anyone able to give some insight?
gpt
The system used to communicate is a bidirectional system which is supported on-earth by NASA (called Nasa Deep Space), which is a really really big radar (EDIT: Antenna) system pointed to the Voyager, ready to capture the signal.
As like any other electromagnetical wave, the radio waves travel at the speed of light; so the time needed for this signal to arrive depends on a lot of things, such as the straight-line (so to say) distance from Earth, and you can calculate it using the equation 

    t = D/c

where *t* is the time, *D* is the distance and *c* is the speed of light.
So if you know the time, for example, you can revert the formula to know the distance, using 

    D = t *x* c

The probe has a relatively big dish-antenna which uses radio frequencies in a certain bandwidth (S-band) to obtain better communication and not to be confused with any other radio signal. So, even if they're actually really weak, we can decode them as we know their exact wavelength.