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FSKProcessor: remove separate channel filter.

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RRC filter alone will do the trick!
This commit is contained in:
Jared Boone
2015-11-07 14:10:44 -08:00
parent fc037c739a
commit 5dcca89172
3 changed files with 29 additions and 177 deletions
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30
firmware/baseband/proc_fsk.cpp
View File

@@ -21,6 +21,8 @@
#include "proc_fsk.hpp"
#include "ais_baseband.hpp"
#include "portapack_shared_memory.hpp"
#include "i2s.hpp"
@@ -43,10 +45,8 @@ FSKProcessor::~FSKProcessor() {
}
void FSKProcessor::configure(const FSKConfiguration new_configuration) {
// TODO: Matched filter characteristics are hard-coded for the moment. YUCK!
decimator.set_decimation_factor(ChannelDecimator::DecimationFactor::By16);
channel_filter.configure(channel_filter_taps.taps, 8);
mf.configure(baseband::ais::rrc_taps_128_decim_4_p, 1);
decimator.set_decimation_factor(ChannelDecimator::DecimationFactor::By32);
mf.configure(baseband::ais::rrc_taps_76k8_4t_p, 4);
clock_recovery.configure(new_configuration.symbol_rate * 2, new_configuration.symbol_rate, { 0.0555f });
packet_builder.configure(
{ new_configuration.access_code, new_configuration.access_code_length, new_configuration.access_code_tolerance },
@@ -59,20 +59,8 @@ void FSKProcessor::execute(buffer_c8_t buffer) {
auto decimator_out = decimator.execute(buffer);
/* 153.6kHz, 128 samples */
const buffer_c16_t work_baseband_buffer {
(complex16_t*)decimator_out.p,
decimator_out.count
};
/* 153.6kHz complex<int16_t>[128]
* -> FIR filter, <?kHz (?fs) pass, gain 1.0
* -> 19.2kHz int16_t[16] */
auto channel = channel_filter.execute(decimator_out, work_baseband_buffer);
/* 76.8kHz, 64 samples */
feed_channel_stats(channel);
feed_channel_stats(decimator_out);
/* No spectrum display while FSK decoding.
feed_channel_spectrum(
channel,
@@ -80,14 +68,12 @@ void FSKProcessor::execute(buffer_c8_t buffer) {
decimator_out.sampling_rate * channel_filter_taps.stop_frequency_normalized
);
*/
// 76.8k
// TODO: Factor out this hidden decimation magic.
for(size_t i=0; i<channel.count; i++) {
for(size_t i=0; i<decimator_out.count; i++) {
// TODO: No idea why implicit cast int16_t->float is not allowed.
const std::complex<float> sample {
static_cast<float>(channel.p[i].real()),
static_cast<float>(channel.p[i].imag())
static_cast<float>(decimator_out.p[i].real()),
static_cast<float>(decimator_out.p[i].imag())
};
if( mf.execute_once(sample) ) {
clock_recovery(mf.get_output());

6
firmware/baseband/proc_fsk.hpp
View File

@@ -25,9 +25,7 @@
#include "baseband_processor.hpp"
#include "channel_decimator.hpp"
#include "dsp_decimate.hpp"
#include "matched_filter.hpp"
#include "dsp_fir_taps.hpp"
#include "clock_recovery.hpp"
#include "symbol_coding.hpp"
@@ -39,8 +37,6 @@
#include <cstddef>
#include <bitset>
#include "ais_baseband.hpp"
class FSKProcessor : public BasebandProcessor {
public:
using payload_t = std::bitset<1024>;
@@ -54,8 +50,6 @@ public:
private:
ChannelDecimator decimator;
const fir_taps_real<64>& channel_filter_taps = taps_64_lp_042_078_tfilter;
dsp::decimate::FIRAndDecimateComplex channel_filter;
dsp::matched_filter::MatchedFilter mf;
clock_recovery::ClockRecovery<clock_recovery::FixedErrorFilter> clock_recovery {