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Transponder
A "transponder" can be defined as a set of satellite equipment which defines one unit of satellite capacity.
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Typically 36 MHz of bandwidth: Horizons-2 contains four transponders with double this amount of bandwidth (i.e., 72 MHz).
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Also comes with a specified radio frequency power, measured dB relative to one watt, or dBW; typical value is 48 dBW at Ku band and 36 dBW at C-band.
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Equipment elements are shown below:
- Section 1 receives the combined uplink and is shared among up to 12 transponders.
- Section 2 contains the RF filters that divide the total bandwidth up into 36 MHz transponders.
- Section 3 provides one power amplifier (PA) per transponder; spare amplifiers are available to replace early failures.
- Section 4 contains more RF filters used to sum up all of the transponder channels and transfer them to the same downlink beam.
Illustration of the repeater section of a geostationary communications satellite - Ku band or C band; equipment for one transponder is indicated.
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A customer may purchase or lease an entire transponder, which dedicates the full bandwidth and power to a particular application or network.
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Alternatively, a customer my lease a portion of one transponder and thereby only pay for what is needed at a particular time.
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When leasing or renting transponder capacity, the customer must determine what level of performance guarantee fits their needs and financial budget. Typical designations used in service level agreements include:
- Protected
- Unprotected
- Preemptable
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