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PiFmRds
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Better PLL frequency selection

This commit is contained in:
SaucySoliton 2017-01-09 20:28:07 +00:00
parent 65cc5be41d
commit 6984fd64b7
1 changed files with 6 additions and 5 deletions
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11
src/pi_fm_rds.c
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@ -397,6 +397,8 @@ terminate(int num)
mem_free(mbox.handle, mbox.mem_ref); mem_free(mbox.handle, mbox.mem_ref);
} }
print_clock_tree();
printf("Terminating: cleanly deactivated the DMA engine and killed the carrier.\n"); printf("Terminating: cleanly deactivated the DMA engine and killed the carrier.\n");
exit(num); exit(num);
@ -814,8 +816,8 @@ int main(int argc, char **argv) {
if( carrier_freq*divider < 760e6 ) continue; // widest accepted frequency range if( carrier_freq*divider < 760e6 ) continue; // widest accepted frequency range
if( carrier_freq*divider > 1300e6 ) break; if( carrier_freq*divider > 1300e6 ) break;
max_int_multiplier=((int)((double)(carrier_freq+100000)*divider*xtal_freq_recip)); max_int_multiplier=((int)((double)(carrier_freq+10+DEVIATION)*divider*xtal_freq_recip));
min_int_multiplier=((int)((double)(carrier_freq-100000)*divider*xtal_freq_recip)); min_int_multiplier=((int)((double)(carrier_freq-10-DEVIATION)*divider*xtal_freq_recip));
if( min_int_multiplier!=max_int_multiplier ) continue; // don't cross integer boundary if( min_int_multiplier!=max_int_multiplier ) continue; // don't cross integer boundary
solution_count++; // if we make it here the solution is acceptable, solution_count++; // if we make it here the solution is acceptable,
@ -833,12 +835,11 @@ int main(int argc, char **argv) {
if( (frac_multiplier>0.2) && (frac_multiplier<0.8) ) fom++; // prefer mulipliers away from integer boundaries if( (frac_multiplier>0.2) && (frac_multiplier<0.8) ) fom++; // prefer mulipliers away from integer boundaries
if( divider%2 == 0 ) fom+=2; // prefer even dividers if( divider%2 == 1 ) fom+=2; // prefer odd dividers
// do odd dividers have worse 2nd harmonic? // odd dividers seem to have 6dB lower 2nd harmonic
//printf(" multiplier:%f divider:%d VCO: %4.1fMHz\n",carrier_freq*divider*xtal_freq_recip,divider,(double)carrier_freq*divider/1e6); //printf(" multiplier:%f divider:%d VCO: %4.1fMHz\n",carrier_freq*divider*xtal_freq_recip,divider,(double)carrier_freq*divider/1e6);
if( fom > best_fom ) if( fom > best_fom )
{ {
best_fom=fom; best_fom=fom;