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BFM decoder: implement RDS decoder

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This commit is contained in:
f4exb 2015-12-13 02:54:22 +01:00
parent dae67170a7
commit 6782c753ad
4 changed files with 29 additions and 8 deletions
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10
plugins/channel/bfm/bfmdemod.cpp
View File

@ -137,11 +137,17 @@ void BFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
if (m_running.m_rdsActive)
{
//Complex r(demod * 2.0 * std::cos(3.0 * m_pilotPLLSamples[2]), 0.0);
Complex r(demod * 2.0 * std::cos(3.0 * m_pilotPLLSamples[2]), m_pilotPLLSamples[2]);
Complex r(demod * 2.0 * std::cos(3.0 * m_pilotPLLSamples[2]), 0.0);
if (m_interpolatorRDS.interpolate(&m_interpolatorRDSDistanceRemain, r, &cr))
{
m_rdsDemod.process(cr.real(), cr.imag());
bool bit;
if (m_rdsDemod.process(cr.real(), bit))
{
m_rdsDecoder.frameSync(bit);
}
m_interpolatorRDSDistanceRemain += m_interpolatorRDSDistance;
}
}

2
plugins/channel/bfm/bfmdemod.h
View File

@ -31,6 +31,7 @@
#include "audio/audiofifo.h"
#include "util/message.h"
#include "rdsdemod.h"
#include "rdsdecoder.h"
#define rfFilterFftLength 1024
@ -192,6 +193,7 @@ private:
Real m_pilotPLLSamples[3];
RDSDemod m_rdsDemod;
RDSDecoder m_rdsDecoder;
LowPassFilterRC m_deemphasisFilterX;
LowPassFilterRC m_deemphasisFilterY;

20
plugins/channel/bfm/rdsdemod.cpp
View File

@ -44,6 +44,7 @@ RDSDemod::RDSDemod() :
m_parms.prev_acc = 0;
m_parms.counter = 0;
m_parms.reading_frame = 0;
m_parms.dbit = 0;
}
RDSDemod::~RDSDemod()
@ -55,8 +56,10 @@ void RDSDemod::setSampleRate(int srate) /// FIXME: fix rate for now
{
}
void RDSDemod::process(Real demod, Real pilot)
bool RDSDemod::process(Real demod, bool& bit)
{
bool ret = false;
m_udpDebug.write(m_parms.lo_clock * m_parms.subcarr_bb[0]);
// Subcarrier downmix & phase recovery
@ -101,7 +104,7 @@ void RDSDemod::process(Real demod, Real pilot)
if (sign(m_parms.lo_clock) != sign(m_parms.prev_lo_clock))
{
biphase(m_parms.acc, m_parms.clock_phi - m_parms.prev_clock_phi);
ret = biphase(m_parms.acc, bit, m_parms.clock_phi - m_parms.prev_clock_phi);
m_parms.acc = 0;
}
@ -112,10 +115,13 @@ void RDSDemod::process(Real demod, Real pilot)
m_parms.prev_bb = m_parms.subcarr_bb[0];
m_parms.prev_clock_phi = m_parms.clock_phi;
m_prev = demod;
return ret;
}
void RDSDemod::biphase(Real acc, Real d_cphi)
bool RDSDemod::biphase(Real acc, bool& bit, Real d_cphi)
{
bool ret = false;
if (sign(acc) != sign(m_parms.prev_acc)) // two successive of different sign: error detected
{
@ -124,7 +130,11 @@ void RDSDemod::biphase(Real acc, Real d_cphi)
if (m_parms.counter % 2 == m_parms.reading_frame) // two successive of the same sing: OK
{
// TODO: take action print_delta(sign(acc + prev_acc));
// new bit found
int b = sign(m_parms.acc + m_parms.prev_acc);
bit = b ^ m_parms.dbit;
m_parms.dbit = b;
ret = true;
}
if (m_parms.counter == 0)
@ -149,6 +159,8 @@ void RDSDemod::biphase(Real acc, Real d_cphi)
m_parms.prev_acc = acc; // memorize (z^-1)
m_parms.counter = (m_parms.counter + 1) % 800;
return ret;
}
Real RDSDemod::filter_lp_2400_iq(Real input, int iqIndex)

5
plugins/channel/bfm/rdsdemod.h
View File

@ -32,10 +32,10 @@ public:
~RDSDemod();
void setSampleRate(int srate);
void process(Real rdsSample, Real pilotSample);
bool process(Real rdsSample, bool &bit);
protected:
void biphase(Real acc, Real d_cphi);
bool biphase(Real acc, bool &bit, Real d_cphi);
Real filter_lp_2400_iq(Real in, int iqIndex);
Real filter_lp_pll(Real input);
int sign(Real a);
@ -58,6 +58,7 @@ private:
int counter;
int reading_frame;
int tot_errs[2];
int dbit;
} m_parms;
Real m_xv[2][2+1];