#define B1MUL 32441
#define B1SMUL -38328
#define B1SHFT 15 // 10 bits gives us plenty of headroom between 31 bits of int and 14 bits of ADC
-#define B2MUL 24593 // This actually matches BETA2 exactly with the supplied BETA1
+#define B2MUL 24593 // This actually matches BETA2 exactly with the supplied BETA1
#define B2SHFT 15 // 10 is also the lowest we can go without beta1=1
#define BETA2 (1.0 - (1.0-BETA1)*DUC_M) // B2MUL/(2**B2SHFT)
#define IN_SCALE 2.0 //Input scaling factor. Should be as large as the amplitude of the incoming samples
//IIR and FIR filter states. Global for go fast.
float f_1,f_2,f;
-int n_1,n_2,n;
+int n_1,n_2,n,m_1,m_2,m;
/*
Upconvert and bandpass filter a chunk of spectrum from Fs/M to Fs. We're going for 700khz here.
}
}
+/*
+ Upconvert and bandpass filter a chunk of spectrum from Fs/M to Fs. We're going for 700khz here.
+ modin needs to be DUC_N long and dac_out needs to be DUC_N*DUC_M long. This
+*/
+
+void iir_upconv_fixp(int modin[], unsigned short dac_out[]){
+ int i,j,k;
+ int l;
+ k=0;
+ //Iterate through input samples and apply pre-eq FIR, interpolate, and apply BPF IIR
+ for(i=0;i<DUC_N;i++){
+ l = modin[i];//(modin[i]*10)>>4;
+ m = l+((m_2*B2MUL)>>B2SHFT);
+ m_2 = m_1;
+ m_1 = l; //Scale fir output and convert to fixed.
+ //m = (int)((f/(IN_SCALE))*DAC_SCALE_2); //Scale fir output and convert to fixed
+ n = m + ((B1SMUL*n_1)>>B1SHFT) - ((B1MUL*n_2)>>B1SHFT); //Apply one cycle of IIR. This feeds the fir-ed sample into the output filter
+ n_2 = n_1;
+ n_1 = n;
+ dac_out[k]=(unsigned short)(n+DAC_SCALE_2);
+ k++;
+ //now do the rest of the filtering. Because we're zero-stuffing we can neglect the sample from the fir filter.
+ for(j=1;j<DUC_M;j++,k++){
+ n = ((B1SMUL*n_1)>>B1SHFT) - ((B1MUL*n_2)>>B1SHFT);
+ n_2 = n_1;
+ n_1 = n;
+ dac_out[k]=(unsigned short)((n)+DAC_SCALE_2);
+ }
+ }
+}
+
#define F48C80R_LEN 25
#define F48C80R_MUL 4096
static int js3 = 0; //Index for downsampling
static int js5 = 0; //Index for upsampling
-static int w48c80r; //Phase for real to comp conversion
+static unsigned int w48c80r; //Phase for real to comp conversion
static int ptr_48c80r; //Pointer in fir delay lines
static int fir_48c80r[]; //Fir filter coeffs
static int fir_48c80r_re[F48C80R_LEN*2]; //Real delay line. Can probably be made much smaller.
static int fir_48c80r_im[F48C80R_LEN*2]; //Imag delay line. Can probably be made much smaller.
+static int * sel_48c80r[2] = {fir_48c80r_re,fir_48c80r_im}; //Selector used to optimize out branches in inner loops
-void upconv_48c_80r(COMP comp_48[],float real_80[],int count){
+/*
+ Interpolate and shift from 48k complex to 80k real, centered on Fs/4.
+ comp_8 - Input samples - 8Kc complex - must be DUC_48N*count long
+ upout - Output samples - must be DUC_N*count long
+ count - how many chunks of samples must be processed
+*/
+
+void upconv_48c_80r(COMP comp_48[],int real_80[],int count){
int i,j,k; //Loop counters
- float ret; //Temp vars
+ int ret; //Temp vars
int nr,ni; //Temp vars
int inidx = 0; //Input index
- int outidx = 0; //Output index
+ int outidx = 0;
+ int ncs_48c80r[3];
for(i=0;i<count;i++){ //Iterate through sample blocks
for(j=0;j<DUC_N*3;j++){ //Iterate through high rate intermediate
if(js5==0){ //Upsample by 5
fir_48c80r_re[ptr_48c80r+F48C80R_LEN] = nr;
fir_48c80r_im[ptr_48c80r+F48C80R_LEN] = ni;
inidx++;
- js5=5;
+ js5=5;
+ if(ptr_48c80r>=F48C80R_LEN)
+ ptr_48c80r-=F48C80R_LEN;
}
if(js3==0){ //Downsample by 3
- nr=0;ni=0;
- if(w48c80r&0x1){ //Only compute FIR for the line we need
- for(k=js5;k<F48C80R_LEN;k+=5) //Skip zero-stuffed samples
- nr+=(fir_48c80r[k]*fir_48c80r_re[ptr_48c80r+k]);
- }else{
- for(k=js5;k<F48C80R_LEN;k+=5)
- ni+=(fir_48c80r[k]*fir_48c80r_im[ptr_48c80r+k]);
- }
- switch(w48c80r&0x3){ //Do comp->real conversion by hand
- case 0:ret=(float)(-ni>>11);break;
- case 1:ret=(float)(nr>>11);break;
- case 2:ret=(float)(ni>>11);break;
- case 3:ret=(float)(-nr>>11);break;
- }
- real_80[outidx]=ret/8192; //Scale back result; should probably just return int
+ ni=0;
+ /*This loop computes the FIR filter. It only computes from either the re or the im delay line,
+ depending on comp->re phase It also skips all 'zeros' in the delay line */
+ for(k=js5;k<F48C80R_LEN;k+=5)
+ ni+=(fir_48c80r[k]*sel_48c80r[w48c80r&0x1][ptr_48c80r+k]);
+ ncs_48c80r[0]=ni;
+ ncs_48c80r[2]=-ni;
+ ret=(ncs_48c80r[w48c80r&0x2]);
+ real_80[outidx]=ret>>14; //Scale back result; should probably just return int
outidx++;
js3=3;
+ w48c80r+=3;
}
- w48c80r++;
ptr_48c80r++;
- if(ptr_48c80r>=F48C80R_LEN)
- ptr_48c80r=0;
js3--;
js5--;
}
}
COMP in[48000];
-float s[NIN];
+int s[NIN];
float fout[NIN];
unsigned short todac[NOUT];
//interpolate from 8k comp to 80k real
upconv_48c_80r(in,s,NOUT_BUFS);
for(i=0;i<NOUT_BUFS;i++)
- iir_upconv(&s[i*(DUC_N)],&todac[i*(DUC_N*DUC_M)]);
+ iir_upconv_fixp(&s[i*(DUC_N)],&todac[i*(DUC_N*DUC_M)]);
f = fopen("iir_duc_s.txt", "wt"); assert(f != NULL);
for(i=0; i<NIN; i++)
- fprintf(f, "%f\n", s[i]);
+ fprintf(f, "%d\n", s[i]);
fprintf(f, "\n");
fclose(f);
#endif
-// constants for a fir filter used to convert 8kc complex to 80kc real
-/*static float fir_8c80r_cic[] = {
-0.000029,-0.000218,0.001966,-0.013414,-0.016592,0.020464,0.029699,-0.037796,
--0.056654,0.070474,0.101466,-0.122748,-0.170446,0.201349,0.275064,-0.319207,
--0.440914,0.506617,0.740998,-0.855843,-1.501563,1.688391,5.983289,5.983289,
-1.688391,-1.501563,-0.855843,0.740998,0.506617,-0.440914,-0.319207,0.275064,
-0.201349,-0.170446,-0.122748,0.101466,0.070474,-0.056654,-0.037796,0.029699,
-
-};*/
//Coeffs for fixed point fir LPF and CIC precompensation
static int fir_8c80r_cic_i[] = {
-0,0,-2,16,-16,-20,26,37,-47,-68,83,116,-139,-187,219,294,-339,-461,528,766,
--882,-1540,1730,6117,6117,1730,-1540,-882,766,528,-461,-339,294,219,-187,-139,116,83,-68,-47,37,26};
-
+ 0, 0, -2, 16, -16, -20, 26, 37, -47, -68,
+ 83, 116, -139, -187, 219, 294, -339, -461, 528, 766,
+ -882,-1540, 1730, 6117, 6117, 1730,-1540, -882, 766, 528,
+ -461, -339, 294, 219, -187, -139, 116, 83, -68, -47,
+ 37, 26,
+};
+
+//Coeffs for fir filter used in 48k comp to 80k real conversion
static int fir_48c80r[] = {
--21, -41, -74, -109, -115, -42, 153, 493, 958, 1483, 1970, 2316, 2441, 2316, 1970, 1483, 958, 493, 153, -42, -115, -109, -74, -41, -21,};
+ -21, -41, -74, -109, -115, -42, 153, 493, 958, 1483,
+ 1970, 2316, 2441, 2316, 1970, 1483, 958, 493, 153, -42,
+ -115, -109, -74, -41, -21,
+};
projects / freetel-svn-tracking.git / commitdiff