G063 - Satellite ‘phones

Learning Objectives: At the end of this topic you should be able to: describe satellite ‘phone communications, describe the advantages and disadvantages of satellite ‘phone systems

Examination question:

How does a Satellite ‘Phone work? a ‘cluster’ of LEO satellites is used 1.number is dialled from a satellite ‘phone 2.satellite ‘phone sends the request to a satellite –using microwaves 3.signal is received & amplified by a satellite 4.signal is transmitted back to a receiver on Earth –or is passed to another satellite 5.signal reaches its recipient –connected via PSTN (if call is to a landline) –or sent to a satellite and then to the receiving satellite phone

Advantages of Satellite Communication global coverage –available any where in the world  people can be contacted wherever they are can be used where other communications not available –remote areas (no landline or mobile network) –after natural disasters more secure than landline/mobile communications –satellite-to-satellite communications don’t use PSTN/cells  can avoid conversations being monitored

Disadvantages of Satellite Communication cost of equipment –satellite phones are expensive compared to mobile ‘phones cost per call is higher than non-satellite methods line of sight to satellite required –won’t work if mountains or buildings in the way a time delay of a fraction of a second –due to large distance between Earth and satellite –makes telephone conversations difficult battery life limited –problem on long expeditions