Satellites

Geosynchronous satellites orbit 22,300 miles above the earth's surface. Because they are so high in the sky, the area to which each satellite is capable of beaming signals is large. This is analogous to a flashlight beam. Holding a flashlight higher in the air extends the amount of area the light illuminates. Lowering the flashlight lessens the amount of area the light covers.

Because they are so high from the earth, geosynchronous satellites introduce a few-seconds delay on voice and data transmissions. Consider voice telephone calls placed in locations where fiber optic cabling is not in place. People who placed calls to international locations in the 1970s and 1980s often experienced clipping and delay. If two people on a telephone call spoke at the same time, parts of words were “clipped” off. The quality of these calls was notably degraded by delays in transmission. The same problem exists in interactive, two-way data communications over satellites.

The reach and broadcast nature of satellite service makes it suitable for paid television service. However, to date the leader in the United States, Hughes' DirectTV service, has only 10 million customers and the next largest provider, EchoStar, has about half that number. By year-end 2000, cable TV had 69 million customers. DirectTV has an additional 3 million customers in Latin America. EchoStar has made an offer to purchase Hughes Electronics from its current owner General Motors.

Low earth-orbiting satellites (LEOs) solve the delay problem because they are positioned from 435 to 1500 miles above the earth. However, placing satellites lower in orbit decreases each satellite's coverage area. Because they are lower in the sky, LEOs cover a smaller area than geosynchronous satellites. Thus more of them are needed for worldwide reach. The requirement for a greater number of satellites increases the cost of LEOs.

Geosynchronous satellites orbit the earth in fixed orbits. In contrast, low earth-orbiting satellites are non-stationary. Therefore, calls need to be handed over to other satellites or points on the earth rather quickly. An advantage to LEOs is that their low position relative to the earth means that lower power is required on the devices and handsets used with LEOs. Lower power translates to lower costs. Regardless of the type, all satellites have a limited life, 7 to 15 years before they “decay” and must be replaced. One service, Teledesic, conceived by Craig McCaw and backed by both McCaw and Microsoft's founder Bill Gates, initially planned to use 840 satellites, but scaled back to 288.

A third type of satellite is called middle earth-orbiting satellite, or MEO. MEOs orbit the earth at 6000 to 13,000 miles up. The 24 GPS satellites owned by the United States government are MEO satellites.

VSAT Service—Small Satellite Dishes

Very small aperture terminals (VSATs) are small satellite dishes that contain antennas that receive and transmit signals between computers and satellites. The dish ranges in size from 24 inches high by 36 inches wide for VSATs used for data communications to 18 inches wide for those used for direct broadcast television. Their small size is possible because of highly focused beams generated from antennas on satellites and the fact that the service is offered at high frequencies, which have shorter wavelengths. The development of VSAT technology in the late 1980s made satellite service affordable for commercial applications where many branch locations transmit back to a central location. These applications include gas stations for transmission of credit authorizations and daily receipts and retail chains for inventory and pricing updates and sales results. The implementation of VSAT networks obviated the need for organizations such as retail chains and postal services to main complex networks of private lines.

Satellite networks are composed of a hub, satellites and receiving antennas on dishes. Receiving antennas also are called ground stations. Receivers on antennas convert airborne signals to electrical signals. The transmitter on the antenna converts electrical signals to airborne (radio frequency) signals. The point from which broadcasts originate is the hub. The hub has a large dish, routing equipment and fiber links to either the enterprise's headquarters for commercial customers or the Internet for Internet access applications. The hub site also is called the network operations center (NOC). For Internet access applications, the NOC has the ISP services such as email and home page on servers. All communications broadcast from the hub travel up to the satellite and then down to the ground stations.

Satellite transmissions consist of broadcasts from the satellite to customers. The downlink from the satellite to the VSAT is relatively simple. All of the signals are broadcast to everyone and each customer takes off data addressed to them. Systems with two-way communications capability have more complexity. The uplink communications from the customer to the satellite are more complex because thousands of users transmit at the same time. The hub needs complex software to be able to manage receiving data from thousands of users without introducing delay.

The two-way VSAT satellite service developed for commercial applications was initially too costly to be offered for residential customers. When customers first used satellites for Internet access it was one-way only. People used a telephone line to send messages to the Internet and the satellite link for receiving Internet data.

Vendors of LEOs

The proliferation of cellular service and the growing availability of transcontinental fiber links have hurt low earth-orbiting satellite networks. In addition, implementation and construction of LEOs requires a long lead time during which user requirements and competitive technologies are developed. To date, none of them have been successful. Teledesic had funding from the former owner, Craig McCaw, of McCaw Cellular. Bill Gates of Microsoft added $10 million and Motorola at one time also invested in the endeavor. Teledesic has combined assets with ICO Global Communications. The combined endeavor, ICO-Teledesic Global Limited, will sell Internet access, mobile voice and data communications to industries such as gas, oil, transportation and construction starting in 2003. ICO service operates with middle earth-orbiting satellites. It's unclear how the two different types of satellites will operate with each other.

Two other LEO providers are Globalstar and Orbcomm. Orbcomm focuses on paging, messaging and tracking services. The satellites are capable of sending two-way data in packet-data format. Its monitoring services are aimed at oil pipeline, gas companies and utility companies for meter reading. Its satellites also are used to track vehicles. Neither company is profitable and Globalstar has said that it might file for bankruptcy. Iridium, which was started by Motorola, filed for bankruptcy in 2000 and was purchased by a private company later in 2000 for $25 million. Seven billion dollars had been invested into Iridium.