CIC compensation filters now follow the 2-stage decimating CIC filters for the I-Q-signals.
The CIC compensation filters are two identical FIR filters (one filter each for the I signal and an identical filter for the Q signal) with currently 81 taps. They flatten the passbands of the CIC filters. At the same time they improve the overall selectivity of the whole filter chain.
The coefficients were calculated in such a way that the filter also acts as a high pass for very low frequencies.
The diagram of the receiver now looks like this:
The following video shows a short excerpt from today’s broadcast:
As you may notice, at the end of the video, the sound slowly fades away.
In order to compensate for that, some sort of AGC will be necessary…