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improved phase unwrapping

chibios
Marshal Horn 2020-07-22 09:25:04 -07:00
rodzic 048e851c47
commit eab3e985a9
1 zmienionych plików z 11 dodań i 6 usunięć
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17
code/radio/ssb.c
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@ -49,6 +49,7 @@ msg_t ssb_tx(mailbox_t * inbox, enum radio_mode * mode, struct synth * txclk){
const int sample_rate = 5000;
int16_t raw[len];
int16_t phase[len];
int16_t tmp_phase=0;
while((USB==*mode) || (LSB==*mode)){
for( int i=0; i<len; ++i){
/** Fetch new data */
@ -62,13 +63,12 @@ msg_t ssb_tx(mailbox_t * inbox, enum radio_mode * mode, struct synth * txclk){
imag=-imag;
uint8_t j = (i-16)&mask; // Match group delay of Hilbert transform
int16_t real = raw[j]; //TODO: Match frequency response of Hilbert transform
phase[i]=arctan3(imag, real);
// Unwrap the phase
j = (i-1)&mask;
if( (phase[i]-phase[j]) > 180 )
phase[i] -=360;
else if( (phase[i]-phase[j]) < 180 )
phase[i] +=360;
int16_t diff = arctan3(imag, real) - tmp_phase;
if( diff > 180 )
diff -=360;
tmp_phase += diff;
phase[i]=tmp_phase;
// Calculate outputs
int16_t amp=magn(imag, real);
int32_t freq = diff32(phase,i);
@ -80,6 +80,11 @@ msg_t ssb_tx(mailbox_t * inbox, enum radio_mode * mode, struct synth * txclk){
synthSetBaseband(txclk, freq);
dacPutChannelX(&DACD1, 1, amp);
}
/** Prevent rollover of phase */
for(int i=0; i<len; ++i){
phase[i]-=tmp_phase;
}
tmp_phase=0;
}
return MSG_OK;
}