Radio communication on the ISS can be carried out in two ways:

– Direct radio communication – between an amateur station on Earth and an amateur station on board the ISS.

– Teleconference – where special amateur radio equipment located somewhere on Earth establishes radio contact with the ISS.

Space radio communication depends on many different factors: range, transmitter power, sizes of onboard and ground antennas, wavelength, quality of transceiver electronics, interference, noise.

Radio waves of different ranges pass through the earth’s atmosphere in different ways. For space communications, the optimal wavelength range is from 1.5 to 30 centimeters.

On Earth, transmission delays are almost not felt, and in orbit it is necessary to speak with a delay.

The answer from the Moon will go one and a half seconds, from Mars – already about six minutes, and the most distant space object with which radio contact is maintained is the American automatic interplanetary station Voyager-1, launched on September 5, 1977. She crossed the line of 100 astronomical units (15 billion kilometers) and came close to the border of the solar system. A radio signal from such a distance takes about 15 hours.