diff --git a/firmware/baseband/dsp_decimate.cpp b/firmware/baseband/dsp_decimate.cpp
index 165fbcfb..930a2fb3 100644
--- a/firmware/baseband/dsp_decimate.cpp
+++ b/firmware/baseband/dsp_decimate.cpp
@@ -197,32 +197,27 @@ buffer_s16_t FIR64AndDecimateBy2Real::execute(
 	return { dst.p, src.count / 2, src.sampling_rate / 2 };
 }
 
-size_t fir_and_decimate_by_2_complex_fast(
-	const complex16_t* const src_start,
-	const size_t src_count,
-	complex16_t* const dst_start,
-	complex16_t* const z,
-	const complex16_t* const taps,
-	const size_t taps_count,
-	const size_t decimation_factor
+buffer_c16_t FIRAndDecimateComplex::execute(
+	buffer_c16_t src,
+	buffer_c16_t dst
 ) {
 	/* int16_t input (sample count "n" must be multiple of decimation_factor)
 	 * -> int16_t output, decimated by decimation_factor.
 	 * taps are normalized to 1 << 16 == 1.0.
 	 */
-	const auto src_p = src_start;
-	auto dst_p = dst_start;
+	const sample_t* src_p = src.p;
+	sample_t* dst_p = dst.p;
 
-	while(src_p < &src_start[src_count]) {
+	while(src_p < &src.p[src.count]) {
 		/* Put two new samples into delay buffer */
-		auto z_new_p = &z[taps_count - decimation_factor];
-		for(size_t i=0; i<decimation_factor; i++) {
+		auto z_new_p = &samples_[taps_count_ - decimation_factor_];
+		for(size_t i=0; i<decimation_factor_; i++) {
 			*__SIMD32(z_new_p)++ = *__SIMD32(src_p)++;
 		}
 
-		size_t loop_count = taps_count / 8;
-		auto t_p = &taps[0];
-		auto z_p = &z[0];
+		size_t loop_count = taps_count_ / 8;
+		auto t_p = &taps_reversed_[0];
+		auto z_p = &samples_[0];
 
 		int64_t t_real = 0;
 		int64_t t_imag = 0;
@@ -282,10 +277,10 @@ size_t fir_and_decimate_by_2_complex_fast(
 
 		/* Shift sample buffer left/down by decimation factor. */
 		const size_t unroll_factor = 4;
-		size_t shift_count = (taps_count - 1) / unroll_factor;
+		size_t shift_count = (taps_count_ - decimation_factor_) / unroll_factor;
 
-		auto t = &z[0];
-		auto s = &z[decimation_factor];
+		sample_t* t = &samples_[0];
+		const sample_t* s = &samples_[decimation_factor_];
 		
 		while(shift_count > 0) {
 			*__SIMD32(t)++ = *__SIMD32(s)++;
@@ -295,14 +290,14 @@ size_t fir_and_decimate_by_2_complex_fast(
 			shift_count--;
 		}
 
-		shift_count = (taps_count - 1) % unroll_factor;
+		shift_count = (taps_count_ - decimation_factor_) % unroll_factor;
 		while(shift_count > 0) {
 			*(t++) = *(s++);
 			shift_count--;
 		}
 	}
 
-	return src_count / decimation_factor;
+	return { dst.p, src.count / decimation_factor_, src.sampling_rate / decimation_factor_ };
 }
 
 buffer_s16_t DecimateBy2CIC4Real::execute(
diff --git a/firmware/baseband/dsp_decimate.hpp b/firmware/baseband/dsp_decimate.hpp
index e24207c6..cbb6204b 100644
--- a/firmware/baseband/dsp_decimate.hpp
+++ b/firmware/baseband/dsp_decimate.hpp
@@ -78,17 +78,7 @@ private:
 	const std::array<int16_t, taps_count>& taps;
 };
 
-size_t fir_and_decimate_by_2_complex_fast(
-	const complex16_t* const src_start,
-	const size_t src_count,
-	complex16_t* const dst_start,
-	complex16_t* const z,
-	const complex16_t* const taps,
-	const size_t taps_count,
-	const size_t decimation_factor
-);
-
-class FIRAndDecimateBy2Complex {
+class FIRAndDecimateComplex {
 public:
 	using sample_t = complex16_t;
 	using tap_t = complex16_t;
@@ -98,18 +88,21 @@ public:
 	/* NOTE! Current code makes an assumption that block of samples to be
 	 * processed will be a multiple of the taps_count.
 	 */
-	FIRAndDecimateBy2Complex(
-	 	const size_t taps_count
+	FIRAndDecimateComplex(
+	 	const size_t taps_count,
+	 	const size_t decimation_factor
 	) : samples_ { std::make_unique<samples_t>(taps_count) },
 		taps_reversed_ { std::make_unique<taps_t>(taps_count) },
-		taps_count_ { taps_count }
+		taps_count_ { taps_count },
+		decimation_factor_ { decimation_factor }
 	{
 	}
 
 	template<typename T>
-	FIRAndDecimateBy2Complex(
-		const T& taps
-	) : FIRAndDecimateBy2Complex(taps.size())
+	FIRAndDecimateComplex(
+		const T& taps,
+		const size_t decimation_factor
+	) : FIRAndDecimateComplex(taps.size(), decimation_factor)
 	{
 		std::reverse_copy(taps.cbegin(), taps.cend(), &taps_reversed_[0]);
 	}
@@ -117,18 +110,15 @@ public:
 	buffer_c16_t execute(
 		buffer_c16_t src,
 		buffer_c16_t dst
-	) {
-		const auto dst_count = fir_and_decimate_by_2_complex_fast(src.p, src.count, dst.p, &samples_[0], &taps_reversed_[0], taps_count_, decimation_factor);
-		return { dst.p, dst_count, src.sampling_rate / decimation_factor };
-	}
-
+	);
+	
 private:
 	using samples_t = sample_t[];
 
 	const std::unique_ptr<samples_t> samples_;
 	const std::unique_ptr<taps_t> taps_reversed_;
 	const size_t taps_count_;
-	const size_t decimation_factor { 2 };
+	const size_t decimation_factor_;
 };
 
 class DecimateBy2CIC4Real {
diff --git a/firmware/baseband/proc_am_audio.hpp b/firmware/baseband/proc_am_audio.hpp
index 1302a2ea..994ff74d 100644
--- a/firmware/baseband/proc_am_audio.hpp
+++ b/firmware/baseband/proc_am_audio.hpp
@@ -38,7 +38,7 @@ public:
 private:
 	ChannelDecimator decimator { ChannelDecimator::DecimationFactor::By32 };
 	const fir_taps_real<64>& channel_filter_taps = taps_64_lp_031_070_tfilter;
-	dsp::decimate::FIRAndDecimateBy2Complex channel_filter { channel_filter_taps.taps };
+	dsp::decimate::FIRAndDecimateComplex channel_filter { channel_filter_taps.taps, 2 };
 	dsp::demodulate::AM demod;
 	IIRBiquadFilter audio_hpf { audio_hpf_config };
 };
diff --git a/firmware/baseband/proc_fsk.hpp b/firmware/baseband/proc_fsk.hpp
index 4af86592..d2324dc9 100644
--- a/firmware/baseband/proc_fsk.hpp
+++ b/firmware/baseband/proc_fsk.hpp
@@ -55,7 +55,7 @@ private:
 	
 	ChannelDecimator decimator { ChannelDecimator::DecimationFactor::By16 };
 	const fir_taps_real<64>& channel_filter_taps = taps_64_lp_031_070_tfilter;
-	dsp::decimate::FIRAndDecimateBy2Complex channel_filter { channel_filter_taps.taps };
+	dsp::decimate::FIRAndDecimateComplex channel_filter { channel_filter_taps.taps, 2 };
 
 	dsp::matched_filter::MatchedFilter mf { baseband::ais::rrc_taps_128_decim_4_p, 1 };
 
diff --git a/firmware/baseband/proc_nfm_audio.hpp b/firmware/baseband/proc_nfm_audio.hpp
index 72437adc..42922ede 100644
--- a/firmware/baseband/proc_nfm_audio.hpp
+++ b/firmware/baseband/proc_nfm_audio.hpp
@@ -39,7 +39,7 @@ public:
 private:
 	ChannelDecimator decimator { ChannelDecimator::DecimationFactor::By32 };
 	const fir_taps_real<64>& channel_filter_taps = taps_64_lp_042_078_tfilter;
-	dsp::decimate::FIRAndDecimateBy2Complex channel_filter { channel_filter_taps.taps };
+	dsp::decimate::FIRAndDecimateComplex channel_filter { channel_filter_taps.taps, 2 };
 	dsp::demodulate::FM demod { 48000, 7500 };
 
 	IIRBiquadFilter audio_hpf { audio_hpf_config };