Digital radio receiver

摘要

The present receiver includes a radiofrequency part (RF) coupled to a limiting amplifier (SL) which is in turn coupled to a demodulation means (DM) which recovers a digital signal from a received signal obtained by modulating a carrier signal with this digital signal. The limiting amplifier (SL) has an input-output characteristic which is substantially linear for smaller input signals and which strives with a decreasing gain towards a limit value for larger input signals. Due to this input-output characteristic smaller received signals are treated linearly up to the demodulation means (DM). The latter can therefore for these signals compensate for a specific spectrum shaping of the digital signal performed before the actual modulation. In this way the receiver will perform in a nearly optimal way resulting in low bit error rates. For larger received signals the limiting amplifier (SL) is non-linear and such compensation is consequently without effect resulting for these signals in a performance degradation. The Latter however is acceptable because these signals are naturally demodulated with less errors.