SCPT vs MCPT: Understanding the Differences

This article explains the difference between SCPT (Single Carrier Per Transponder) and MCPT (Multiple Carrier Per Transponder) techniques used in satellite communication.

As we know, satellites are commonly used for wireless communication, primarily in the C band and Ku band frequencies. Their main application is to connect remote and inaccessible areas, fulfilling basic communication needs such as voice and data transmission. Nowadays, even video and TV transmission are possible due to the availability of high-bandwidth modems and other supporting devices.

However, satellite resources are limited and scarce. A satellite has a limited bandwidth of approximately 500 MHz in both the C band and Ku band.

This total bandwidth is divided into smaller bandwidths, each used by a single transponder. Typically, one transponder has a bandwidth of 36 MHz. Depending on the application’s bandwidth demand, either SCPT or MCPT is employed.

MCPT (Multiple Carrier Per Transponder)

MCPT-Multiple Carrier Per Transponder

MCPT is generally used in situations where the bandwidth requirement is relatively low. In this approach, the 36 MHz bandwidth of a satellite transponder is shared by multiple earth stations simultaneously using different, non-overlapping frequencies. This is achieved using FDMA (Frequency Division Multiple Access).

For example, 2.5 MHz might be allocated to each earth station. Refer to FDMA vs TDMA vs CDMA for a detailed description of FDMA, TDMA, and CDMA multiple access techniques.

SCPT (Single Carrier Per Transponder)

SCPT-Single Carrier Per Transponder

SCPT is deployed in scenarios requiring higher bandwidth, such as television transmission. In SCPT, the entire bandwidth of the transponder (approximately 36 MHz) is used by a single earth station.

This is utilized to uplink data from multiple TV stations for broadcasting or relaying. The satellite typically picks up these high-bandwidth signals and broadcasts them over a larger area of the Earth. This approach is known as SCPT, or Single Carrier Per Transponder.