Next-Generation Satellite telecommunication payloads will require extended functionalities and more flexibility, which will result in increasing the complexity and the capability requiring a large number of frequency converters. The implementation of the satellite digital/RF payload is traditionally carried out by using several frequency down-conversion stages, thus requiring LOs, mixers, amplifiers, filters, from the native frequency (e.g. Ka band) to the down-converted frequency.
This traditional frequency down-conversion process has some limitations that have to be carefully taken into account in the system design. For example, some effects from the RF chain are the LO leakage, the image rejection, which requires the use of different down-conversion and filtering stages (super-heterodyne configuration), the phase noise and frequency/amplitude stability of the oscillators, the conversion losses, etc. These issues make the design complex, which impacts on achieving reduced size, mass (limited by mechanical isolations for avoiding EMI and leakage effects) and power consumption.
By carrying out a sub-sampling technique for the RF signals down-conversion process the system complexity may be significantly reduced by mitigating, or even eliminating, the previously described issues and obtaining substantial improvements in performance by saving mass, volume, complexity and cost thanks to the use of distributed architectures and fiber optic remote delivery.