GSM – Global System Mobile Communications (GSM), which is digital, is used by phone companies such as AT&T, Cingular and T-Mobile in the U.S. It operates at either the 900 Megahertz (MHz), the current Australian allocation, or 1800 MHz frequency band. In locations where Cellular Phone Networks with data capabilities are available, small size and low power consumption GSM Modems are the best choice for telemetry. This is the usual LDS configuration.

CDMA – Code Division Multiple Access (CDMA) modems are country specific. Sprint and Verizon Wireless in the U.S. and Telus in Canada use CDMA, which is all digital. It usually operates at the 800 MHz frequency band, but is also country specific. This is not available with the standard LDS system, but can be implemented if required.

AMPS – Advanced Mobile Phone Service (AMPS ) is a standard system for analog signal cellular telephone service in the United States and is also used in other countries. AMPS allocates frequency ranges within the 800 and 900 MHz spectrum to cellular telephone.

Radio Telemetry

This type of telemetry is used if cell phone coverage at the lake station is not available. Line-of-sight is required and typically the lake station and the shore installation must be less than 15km apart. The system (Freewave modem) is a commercial 915-928 Mhz spread spectrum modem configured as back-to-back RS232 links. Antennae used are 5dB omnidirections.

Radio telemetry is used to link the lake station to a shore installation. This installation may be the shore station, or it may be an intermediate where a modem is connected to telephone land line, or to a cell phone. Single or multiple lake stations can optionally be supported.

Satellite Telemetry

This type of telemetry is used if cell phone coverage or land-line telephone are not available. The Iridium satellite system is used.

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