Satellite to Satellite Communication
How it works
Optical communications in free space between two satellites traditionally have used microwaves as the data carrier. A system using optical frequencies requires the satellites to have both a transmitter and a receiver that typically share the optical antenna, and a mechanism for beam steering an on board laser. A beam splitter is also used at the receiving end: half the beam goes to the optical detector for demodulation and decoding, while the other half is used to adjust the receive antenna to make sure the beam is centered.
Advantages/Disadvantages
Advantages:
- Much faster data rates than with using the traditional microwave method.
- Direct point-to-point signals at very high frequencies mean less interference with outside signals
- Transmitting in free space also introduces interference from background radiation, most notably the Sun.
- Point to-Point signals make it difficult to aim receiver at the very small beam being transmitted.
- A new system means new infrastructure which means new (expensive) equipment including telescopes, lasers, mirrors, detectors, a pointing and tracking system and control electronics