Add sliding-frequency audio receiver tuning

firmware/baseband/proc_nfm_audio.hpp

@@ -29,6 +29,7 @@
 
 #include "dsp_decimate.hpp"
 #include "dsp_demodulate.hpp"
+#include "dsp_frequency_xlator.hpp"
 #include "dsp_iir.hpp"
 
 #include "audio_output.hpp"
@@ -50,6 +51,7 @@ class NarrowbandFMAudio : public BasebandProcessor {
 
    private:
     static constexpr size_t baseband_fs = 3072000;
+    static constexpr auto spectrum_rate_hz = 30.0f;
 
     std::array<complex16_t, 512> dst{};
     const buffer_c16_t dst_buffer{
@@ -69,8 +71,9 @@ class NarrowbandFMAudio : public BasebandProcessor {
         (int16_t*)tone.data(),
         sizeof(tone) / sizeof(int16_t)};
 
-    dsp::decimate::FIRC8xR16x24FS4Decim8 decim_0{};
-    dsp::decimate::FIRC16xR16x32Decim8 decim_1{};
+    dsp::decimate::FIRC8xR16x24FS4Decim4 decim_0{};
+    dsp::decimate::FIRC16xR16x16Decim2 audio_decim_0{};
+    dsp::FrequencyTranslatingDecimator32By8 translating_decim_1{};
     dsp::decimate::FIRAndDecimateComplex channel_filter{};
     int32_t channel_filter_low_f = 0;
     int32_t channel_filter_high_f = 0;
@@ -85,6 +88,9 @@ class NarrowbandFMAudio : public BasebandProcessor {
     AudioOutput audio_output{};
 
     SpectrumCollector channel_spectrum{};
+    size_t spectrum_interval_samples{0};
+    size_t spectrum_samples{0};
+    bool spectrum_capture_active{false};
 
     uint32_t tone_phase{0};
     uint32_t tone_delta{0};
@@ -113,6 +119,7 @@ class NarrowbandFMAudio : public BasebandProcessor {
     void pitch_rssi_config(const PitchRSSIConfigureMessage& message);
     void configure(const NBFMConfigureMessage& message);
     void capture_config(const CaptureConfigMessage& message);
+    void ddc_config(const AudioDDCConfigMessage& message);
 };
 
 #endif /*__PROC_NFM_AUDIO_H__*/