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Allow 2.5MHz bandwidth on R2 use without filter optimization if needed. #107

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Allow 2.5MHz bandwidth on R2 use without filter optimization if needed. #107

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e0416c0
Allow 2.5MHz bandwidth on R2 use without filter optimization if needed.
Mar 22, 2023
bcc09cb
Merge branch 'TLeconte:master' into airspy-r2-freq-selection-fix
murrayma Sep 21, 2023
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21 changes: 14 additions & 7 deletions air.c
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Original file line number Diff line number Diff line change
Expand Up @@ -45,19 +45,26 @@ static unsigned int chooseFc(unsigned int minF,unsigned int maxF,int filter)
int i,j;

if(filter) {
/* The reasoning and research for this is described here:
* https://tleconte.github.io/R820T/r820IF.html */

for(i=7;i>=0;i--)
if((r820t_hf[5]-r820t_lf[i])>=bw) break;

if(i<0) return 0;
if(i<0) {
fprintf(stderr, "Unable to use airspy R820T filter optimization, continuing.\n");
} else {
fprintf(stderr, "Enabling airspy R820T filter optimization.\n");

for(j=5;j>=0;j--)
if((r820t_hf[j]-r820t_lf[i])<=bw) break;
j++;
for(j=5;j>=0;j--)
if((r820t_hf[j]-r820t_lf[i])<=bw) break;
j++;

off=(r820t_hf[j]+r820t_lf[i])/2-AIRINRATE/4;
off=(r820t_hf[j]+r820t_lf[i])/2-AIRINRATE/4;

airspy_r820t_write(device, 10, 0xB0 | (15-j));
airspy_r820t_write(device, 11, 0xE0 | (15-i));
airspy_r820t_write(device, 10, 0xB0 | (15-j));
airspy_r820t_write(device, 11, 0xE0 | (15-i));
}
}

return(((maxF+minF)/2+off+INTRATE/2)/INTRATE*INTRATE);
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