Satellites used for communications are typically placed in geostationary orbit, which is at an altitude of approximately 36,000 kilometers (22,236 miles) above Earth's equator. This specific orbit allows the satellite to match the rotation of the Earth, appearing to hover over a fixed point on the ground. As a result, the satellite remains in a constant position relative to an observer on Earth, making it ideal for communication purposes such as television broadcasting, internet connectivity, and telephone services.
On the other hand, satellites orbiting at 1,000 kilometers above Earth's surface would not be suitable for communications due to their much lower altitude. Satellites at this altitude would have a much faster orbital period and would not appear stationary relative to the Earth's surface. They would move across the sky relatively quickly and would require more satellites to maintain consistent coverage, which is not efficient for communication purposes. Lower altitude orbits are often used for Earth observation, scientific research, and certain types of remote sensing, rather than for communication purposes.