How Satellite Telephones Work
Ever wondered how satellite telephones work? A few years ago satellite phones cost in excess of $10,000 and charges for calls were $10 per minute! These days, however, international call charges from a satellite phone are cheaper than a GSM mobile cell phone and coverage is global so if you are, for example, a keen traveler or live in a rural location for weeks or months at a time, a satellite telephone is the perfect way to stay in touch. So! How do satellite telephones work? Satellite telephones are basically a type of phone that sends radio signals direct to a satellite in space and then down to an earth station. From here, the call is connected to the public switched telephone network (PSTN). Almost as if by magic, you can call anyone, anywhere at any time.
Here’s how a High Speed Satellite Internet Service allows you to use a telephone via satellite:
* The best satellite systems offer telephone and fax over a satellite Internet link via a hardware-based solution that doesn’t require a PC or specific software. This kind of system works via your high speed satellite Internet connection in the same way as your home telephone does.
* High speed satellite Internet remote sites are able to answer normal telephone calls dialed to a standard ten-digit telephone number and 800 numbers. Outgoing calls from the site may use any selected 1+ long-distance carrier, calling cards or 10-10-XXX access.
* Satellite telephones work really well for users in remote locations and using high speed satellite Internet service where access to traditional telephone service is not available. It isn’t really designed to save money on long distance calls.
* Of course the quality of sound you will receive over satellite telephones is similar to that of a cell phone. There is also a slight delay. If a dedicated satellite voice channel with QoS (Quality of Service) is added to your system you can improve on the quality and availability of your service.
* Once the call reaches the remote site, calls are handled by a remote terminal. Where the system joins the ordinary telephone network there is a host terminal. A host terminal can support two or more remote terminals that are configured in a range of ways.
* High speed satellite systems usually feature a specifically configured hardware terminal at each end of a connection. A telephone jack located at the remote site on the remote terminal is connected to a customer-provided telephone or FAX machine. A remote terminal is connected to the satellite Internet service via a standard Ethernet connection.
* On the landline end the host terminal is connected via Ethernet to the customers LAN switch or hub. The host terminal features a standard telephone jack which connects to the standard telephone line. Telephone calls made to the remote site telephone number will ring through as though the remote site telephone were in the same room as the host terminal although there is a three-quarter of a second of delay.
* Calls made via the remote side will be local if local to the telephone line, or are placed through the selected long distance carrier.
* Even though it does seem to be an almost mystical way of communication there are a few natural laws that satellite telephones can’t break:
* Satellite telephones need a clear line-of-sight view of the satellite.
* For an Iridium Satellite telephone, for example, this means that the phone’s antenna must be outside with a relatively unobstructed view of most of the sky. Iridium phones use a non-directional antenna. This means you don’t have to point it in any direction.
* Inmarsat telephones use geostationary satellites so the antenna does need to point directly at the satellite with an unobstructed view. The antenna will also need to be outside, but it’s fairly easy to set up. The Inmarsat system makes use or four satellites which are positioned above the equator.
* If you need to operate the phones inside a building a long antenna cable extension is fitted. This allows the telephone handset to be used inside. If you will be inside a vehicle or for maritime use, the Inmarsat is fitted with an optional automatic antenna, which points itself towards the satellite.
*Limited Bandwidth
* Satellite telephones work by sharing the limited resources of a satellite amongst users in many different countries. Satellite engineers have developed astounding systems that allow narrow-band carriers to be used to carry our voice signals.
* The technology isn’t capable of delivering high bandwidth data. Even though Internet access is possible, connections can be very slow.
* Higher bandwidth options require a large antenna version of the Inmarsat system – Inmarsat M4. or a Satellite Broadband option which uses DVB-RCS technology.
Satellite telephones are invaluable for many fields of work, for example news reporting, working with wildlife or in field medicine and can be a life-saver in an emergency or disaster situation.
Most of us won’t need to make use of a satellite telephone in the normal course of events but if you do choose to invest in one at least you will be able to say you know how satellite telephones work. I am quite sure it will impress your friends!