A system to collect energy from generation systems such as, for example, wind farms or solar farms with distributed energy-generation equipment. The value of an operational datum of the lamp which varies in time is continuously or discontinuously measured and the frequency of the alternating voltage or the alternating current is selected in dependence on the measured values. A downconversion mixer may be coupled to the transconductor input stage via a low impedance current cascode stage, and may operate to create a set of current-mode quadrature baseband signals from the current-mode modulated signal. Movements between concrete members of the joint are compensated by a free extension of the folded cover strip.