diff --git a/demod/mod/demod_mod.c b/demod/mod/demod_mod.c
index a432647..529796f 100644
--- a/demod/mod/demod_mod.c
+++ b/demod/mod/demod_mod.c
@@ -304,6 +304,7 @@ float read_wav_header(pcm_t *pcm, FILE *fp) {
 
     if (bits_sample != 8 && bits_sample != 16 && bits_sample != 32) return -1;
 
+    if (sample_rate == 900001) sample_rate -= 1;
 
     pcm->sr  = sample_rate;
     pcm->bps = bits_sample;
@@ -346,6 +347,7 @@ typedef struct {
     double sumIQy;
     float avgIQx;
     float avgIQy;
+    float complex avgIQ;
     ui32_t cnt;
     ui32_t maxcnt;
     ui32_t maxlim;
@@ -375,16 +377,22 @@ static int f32read_csample(dsp_t *dsp, float complex *z) {
         y = (u[1]-128)/128.0;
     }
 
-    *z = (x - IQdc.avgIQx) + I*(y - IQdc.avgIQy);
+    *z = x + I*y;
 
-    IQdc.sumIQx += x;
-    IQdc.sumIQy += y;
-    IQdc.cnt += 1;
-    if (IQdc.cnt == IQdc.maxcnt) {
-        IQdc.avgIQx = IQdc.sumIQx/(float)IQdc.maxcnt;
-        IQdc.avgIQy = IQdc.sumIQy/(float)IQdc.maxcnt;
-        IQdc.sumIQx = 0; IQdc.sumIQy = 0; IQdc.cnt = 0;
-        if (IQdc.maxcnt < IQdc.maxlim) IQdc.maxcnt *= 2;
+    // IQ-dc removal optional
+    if (dsp->opt_iqdc) {
+        *z -= IQdc.avgIQ;
+
+        IQdc.sumIQx += x;
+        IQdc.sumIQy += y;
+        IQdc.cnt += 1;
+        if (IQdc.cnt == IQdc.maxcnt) {
+            IQdc.avgIQx = IQdc.sumIQx/(float)IQdc.maxcnt;
+            IQdc.avgIQy = IQdc.sumIQy/(float)IQdc.maxcnt;
+            IQdc.avgIQ  = IQdc.avgIQx + I*IQdc.avgIQy;
+            IQdc.sumIQx = 0; IQdc.sumIQy = 0; IQdc.cnt = 0;
+            if (IQdc.maxcnt < IQdc.maxlim) IQdc.maxcnt *= 2;
+        }
     }
 
     return 0;
@@ -395,63 +403,42 @@ static int f32read_cblock(dsp_t *dsp) {
     int n;
     int len;
     float x, y;
+    ui8_t s[4*2*dsp->decM]; //uin8,int16,flot32
+    ui8_t *u = (ui8_t*)s;
+    short *b = (short*)s;
+    float *f = (float*)s;
 
-    len = dsp->decM;
 
-    if (dsp->bps == 8) { //uint8
-        ui8_t u[2*dsp->decM];
-        len = fread( u, dsp->bps/8, 2*dsp->decM, dsp->fp) / 2;
-        //for (n = 0; n < len; n++) dsp->decMbuf[n] = (u[2*n]-128)/128.0 + I*(u[2*n+1]-128)/128.0;
-        // u8: 0..255, 128 -> 0V
-        for (n = 0; n < len; n++) {
+    len = fread( s, dsp->bps/8, 2*dsp->decM, dsp->fp) / 2;
+
+    //for (n = 0; n < len; n++) dsp->decMbuf[n] = (u[2*n]-128)/128.0 + I*(u[2*n+1]-128)/128.0;
+    // u8: 0..255, 128 -> 0V
+    for (n = 0; n < len; n++) {
+        if (dsp->bps == 8) { //uint8
             x = (u[2*n  ]-128)/128.0;
             y = (u[2*n+1]-128)/128.0;
-            dsp->decMbuf[n] = (x-IQdc.avgIQx) + I*(y-IQdc.avgIQy);
-            IQdc.sumIQx += x;
-            IQdc.sumIQy += y;
-            IQdc.cnt += 1;
-            if (IQdc.cnt == IQdc.maxcnt) {
-                IQdc.avgIQx = IQdc.sumIQx/(float)IQdc.maxcnt;
-                IQdc.avgIQy = IQdc.sumIQy/(float)IQdc.maxcnt;
-                IQdc.sumIQx = 0; IQdc.sumIQy = 0; IQdc.cnt = 0;
-                if (IQdc.maxcnt < IQdc.maxlim) IQdc.maxcnt *= 2;
-            }
         }
-    }
-    else if (dsp->bps == 16) { //int16
-        short b[2*dsp->decM];
-        len = fread( b, dsp->bps/8, 2*dsp->decM, dsp->fp) / 2;
-        for (n = 0; n < len; n++) {
+        else if (dsp->bps == 16) { //int16
             x = b[2*n  ]/32768.0;
             y = b[2*n+1]/32768.0;
-            dsp->decMbuf[n] = (x-IQdc.avgIQx) + I*(y-IQdc.avgIQy);
-            IQdc.sumIQx += x;
-            IQdc.sumIQy += y;
-            IQdc.cnt += 1;
-            if (IQdc.cnt == IQdc.maxcnt) {
-                IQdc.avgIQx = IQdc.sumIQx/(float)IQdc.maxcnt;
-                IQdc.avgIQy = IQdc.sumIQy/(float)IQdc.maxcnt;
-                IQdc.sumIQx = 0; IQdc.sumIQy = 0; IQdc.cnt = 0;
-                if (IQdc.maxcnt < IQdc.maxlim) IQdc.maxcnt *= 2;
-            }
         }
-    }
-    else { // dsp->bps == 32   //float32
-        float f[2*dsp->decM];
-        len = fread( f, dsp->bps/8, 2*dsp->decM, dsp->fp) / 2;
-        for (n = 0; n < len; n++) {
+        else { // dsp->bps == 32   //float32
             x = f[2*n];
             y = f[2*n+1];
-            dsp->decMbuf[n] = (x-IQdc.avgIQx) + I*(y-IQdc.avgIQy);
-            IQdc.sumIQx += x;
-            IQdc.sumIQy += y;
-            IQdc.cnt += 1;
-            if (IQdc.cnt == IQdc.maxcnt) {
-                IQdc.avgIQx = IQdc.sumIQx/(float)IQdc.maxcnt;
-                IQdc.avgIQy = IQdc.sumIQy/(float)IQdc.maxcnt;
-                IQdc.sumIQx = 0; IQdc.sumIQy = 0; IQdc.cnt = 0;
-                if (IQdc.maxcnt < IQdc.maxlim) IQdc.maxcnt *= 2;
-            }
+        }
+
+        // baseband: IQ-dc removal mandatory
+        dsp->decMbuf[n] = (x-IQdc.avgIQx) + I*(y-IQdc.avgIQy);
+
+        IQdc.sumIQx += x;
+        IQdc.sumIQy += y;
+        IQdc.cnt += 1;
+        if (IQdc.cnt == IQdc.maxcnt) {
+            IQdc.avgIQx = IQdc.sumIQx/(float)IQdc.maxcnt;
+            IQdc.avgIQy = IQdc.sumIQy/(float)IQdc.maxcnt;
+            IQdc.avgIQ  = IQdc.avgIQx + I*IQdc.avgIQy;
+            IQdc.sumIQx = 0; IQdc.sumIQy = 0; IQdc.cnt = 0;
+            if (IQdc.maxcnt < IQdc.maxlim) IQdc.maxcnt *= 2;
         }
     }
 
diff --git a/demod/mod/demod_mod.h b/demod/mod/demod_mod.h
index 26934fd..d2a2879 100644
--- a/demod/mod/demod_mod.h
+++ b/demod/mod/demod_mod.h
@@ -67,6 +67,7 @@ typedef struct {
 
     // IQ-data
     int opt_iq;
+    int opt_iqdc;
     int N_IQBUF;
     float complex *rot_iqbuf;
     float complex F1sum;
diff --git a/demod/mod/dfm09mod.c b/demod/mod/dfm09mod.c
index 1712c89..3edb3ed 100644
--- a/demod/mod/dfm09mod.c
+++ b/demod/mod/dfm09mod.c
@@ -897,6 +897,7 @@ int main(int argc, char **argv) {
     int option_auto = 0;
     int option_min = 0;
     int option_iq = 0;
+    int option_iqdc = 0;
     int option_lp = 0;
     int option_dc = 0;
     int option_bin = 0;
@@ -1009,6 +1010,7 @@ int main(int argc, char **argv) {
         else if   (strcmp(*argv, "--iq0") == 0) { option_iq = 1; }  // differential/FM-demod
         else if   (strcmp(*argv, "--iq2") == 0) { option_iq = 2; }
         else if   (strcmp(*argv, "--iq3") == 0) { option_iq = 3; }  // iq2==iq3
+        else if   (strcmp(*argv, "--iqdc") == 0) { option_iqdc = 1; }  // iq-dc removal (iq0,2,3)
         else if   (strcmp(*argv, "--IQ") == 0) { // fq baseband -> IF (rotate from and decimate)
             double fq = 0.0;                     // --IQ <fq> , -0.5 < fq < 0.5
             ++argv;
@@ -1147,6 +1149,7 @@ int main(int argc, char **argv) {
         dsp.BT = 0.5; // bw/time (ISI) // 0.3..0.5
         dsp.h = 1.8;  // 2.4 modulation index abzgl. BT
         dsp.opt_iq = option_iq;
+        dsp.opt_iqdc = option_iqdc;
         dsp.opt_lp = option_lp;
         dsp.lpIQ_bw = lpIQ_bw;  // 12e3; // IF lowpass bandwidth
         dsp.lpFM_bw = 4e3; // FM audio lowpass
diff --git a/demod/mod/lms6Xmod.c b/demod/mod/lms6Xmod.c
index 2632790..6f90e7c 100644
--- a/demod/mod/lms6Xmod.c
+++ b/demod/mod/lms6Xmod.c
@@ -949,6 +949,7 @@ int main(int argc, char **argv) {
     int option_inv = 0;    // invertiert Signal
     int option_min = 0;
     int option_iq = 0;
+    int option_iqdc = 0;
     int option_lp = 0;
     int option_dc = 0;
     int option_softin = 0;
@@ -1073,6 +1074,7 @@ int main(int argc, char **argv) {
         else if   (strcmp(*argv, "--iq0") == 0) { option_iq = 1; }  // differential/FM-demod
         else if   (strcmp(*argv, "--iq2") == 0) { option_iq = 2; }
         else if   (strcmp(*argv, "--iq3") == 0) { option_iq = 3; }  // iq2==iq3
+        else if   (strcmp(*argv, "--iqdc") == 0) { option_iqdc = 1; }  // iq-dc removal (iq0,2,3)
         else if   (strcmp(*argv, "--IQ") == 0) { // fq baseband -> IF (rotate from and decimate)
             double fq = 0.0;                     // --IQ <fq> , -0.5 < fq < 0.5
             ++argv;
@@ -1199,6 +1201,7 @@ int main(int argc, char **argv) {
         dsp.BT = 1.2; // bw/time (ISI) // 1.0..2.0  // BT(lmsX) < BT(lms6) ? -> init_buffers()
         dsp.h = 0.9;  // 0.95 modulation index
         dsp.opt_iq = option_iq;
+        dsp.opt_iqdc = option_iqdc;
         dsp.opt_lp = option_lp;
         dsp.lpIQ_bw = lpIQ_bw;  // 16e3; // IF lowpass bandwidth // soft decoding?
         dsp.lpFM_bw = 6e3; // FM audio lowpass
diff --git a/demod/mod/m10mod.c b/demod/mod/m10mod.c
index 8e47984..1622a78 100644
--- a/demod/mod/m10mod.c
+++ b/demod/mod/m10mod.c
@@ -1115,6 +1115,7 @@ int main(int argc, char **argv) {
     int option_ptu = 0;
     int option_min = 0;
     int option_iq = 0;
+    int option_iqdc = 0;
     int option_lp = 0;
     int option_dc = 0;
     int option_chk = 0;
@@ -1214,6 +1215,7 @@ int main(int argc, char **argv) {
         else if   (strcmp(*argv, "--iq0") == 0) { option_iq = 1; }  // differential/FM-demod
         else if   (strcmp(*argv, "--iq2") == 0) { option_iq = 2; }
         else if   (strcmp(*argv, "--iq3") == 0) { option_iq = 3; }  // iq2==iq3
+        else if   (strcmp(*argv, "--iqdc") == 0) { option_iqdc = 1; }  // iq-dc removal (iq0,2,3)
         else if   (strcmp(*argv, "--IQ") == 0) { // fq baseband -> IF (rotate from and decimate)
             double fq = 0.0;                     // --IQ <fq> , -0.5 < fq < 0.5
             ++argv;
@@ -1313,6 +1315,7 @@ int main(int argc, char **argv) {
         dsp.BT = 1.8; // bw/time (ISI) // 1.0..2.0
         dsp.h = 0.9;  // 1.2 modulation index
         dsp.opt_iq = option_iq;
+        dsp.opt_iqdc = option_iqdc;
         dsp.opt_lp = option_lp;
         dsp.lpIQ_bw = 24e3; // IF lowpass bandwidth
         dsp.lpFM_bw = 10e3; // FM audio lowpass
diff --git a/demod/mod/mXXmod.c b/demod/mod/mXXmod.c
index f33a246..4656cb3 100644
--- a/demod/mod/mXXmod.c
+++ b/demod/mod/mXXmod.c
@@ -755,6 +755,7 @@ int main(int argc, char **argv) {
     int option_ptu = 0;
     int option_min = 0;
     int option_iq = 0;
+    int option_iqdc = 0;
     int option_lp = 0;
     int option_dc = 0;
     int option_softin = 0;
@@ -862,6 +863,7 @@ int main(int argc, char **argv) {
         else if   (strcmp(*argv, "--iq0") == 0) { option_iq = 1; }  // differential/FM-demod
         else if   (strcmp(*argv, "--iq2") == 0) { option_iq = 2; }
         else if   (strcmp(*argv, "--iq3") == 0) { option_iq = 3; }  // iq2==iq3
+        else if   (strcmp(*argv, "--iqdc") == 0) { option_iqdc = 1; }  // iq-dc removal (iq0,2,3)
         else if   (strcmp(*argv, "--IQ") == 0) { // fq baseband -> IF (rotate from and decimate)
             double fq = 0.0;                     // --IQ <fq> , -0.5 < fq < 0.5
             ++argv;
@@ -961,6 +963,7 @@ int main(int argc, char **argv) {
         dsp.BT = 1.8; // bw/time (ISI) // 1.0..2.0  // M20 ?
         dsp.h = 0.9;  // 1.2 modulation index       // M20 ?
         dsp.opt_iq = option_iq;
+        dsp.opt_iqdc = option_iqdc;
         dsp.opt_lp = option_lp;
         dsp.lpIQ_bw = 24e3; // IF lowpass bandwidth
         dsp.lpFM_bw = 10e3; // FM audio lowpass
diff --git a/demod/mod/meisei100mod.c b/demod/mod/meisei100mod.c
index 6397c5a..815ec88 100644
--- a/demod/mod/meisei100mod.c
+++ b/demod/mod/meisei100mod.c
@@ -210,6 +210,7 @@ int main(int argc, char **argv) {
         option_jsn = 0;    // JSON output (auto_rx)
     int option_min = 0;
     int option_iq = 0;
+    int option_iqdc = 0;
     int option_lp = 0;
     int option_dc = 0;
     int option_softin = 0;
@@ -332,6 +333,7 @@ int main(int argc, char **argv) {
         else if   (strcmp(*argv, "--iq0") == 0) { option_iq = 1; }  // differential/FM-demod
         else if   (strcmp(*argv, "--iq2") == 0) { option_iq = 2; }
         else if   (strcmp(*argv, "--iq3") == 0) { option_iq = 3; }  // iq2==iq3
+        else if   (strcmp(*argv, "--iqdc") == 0) { option_iqdc = 1; }  // iq-dc removal (iq0,2,3)
         else if   (strcmp(*argv, "--IQ") == 0) { // fq baseband -> IF (rotate from and decimate)
             double fq = 0.0;                     // --IQ <fq> , -0.5 < fq < 0.5
             ++argv;
@@ -427,6 +429,7 @@ int main(int argc, char **argv) {
         dsp.BT = 1.2; // bw/time (ISI) // 1.0..2.0
         dsp.h = 2.4;  // 2.8
         dsp.opt_iq = option_iq;
+        dsp.opt_iqdc = option_iqdc;
         dsp.opt_lp = option_lp;
         dsp.lpIQ_bw = 16e3; // IF lowpass bandwidth
         dsp.lpFM_bw = 4e3; // FM audio lowpass
diff --git a/demod/mod/rs41mod.c b/demod/mod/rs41mod.c
index 95ee379..25b6147 100644
--- a/demod/mod/rs41mod.c
+++ b/demod/mod/rs41mod.c
@@ -1749,6 +1749,7 @@ int main(int argc, char *argv[]) {
     //int option_inv = 0;    // invertiert Signal
     int option_min = 0;
     int option_iq = 0;
+    int option_iqdc = 0;
     int option_lp = 0;
     int option_dc = 0;
     int option_bin = 0;
@@ -1856,6 +1857,7 @@ int main(int argc, char *argv[]) {
         else if   (strcmp(*argv, "--iq0") == 0) { option_iq = 1; }  // differential/FM-demod
         else if   (strcmp(*argv, "--iq2") == 0) { option_iq = 2; }
         else if   (strcmp(*argv, "--iq3") == 0) { option_iq = 3; }  // iq2==iq3
+        else if   (strcmp(*argv, "--iqdc") == 0) { option_iqdc = 1; }  // iq-dc removal (iq0,2,3)
         else if   (strcmp(*argv, "--IQ") == 0) { // fq baseband -> IF (rotate from and decimate)
             double fq = 0.0;                     // --IQ <fq> , -0.5 < fq < 0.5
             ++argv;
@@ -1973,6 +1975,7 @@ int main(int argc, char *argv[]) {
             dsp.BT = 0.5; // bw/time (ISI) // 0.3..0.5
             dsp.h = 0.6; //0.7;  // 0.7..0.8? modulation index abzgl. BT
             dsp.opt_iq = option_iq;
+            dsp.opt_iqdc = option_iqdc;
             dsp.opt_lp = option_lp;
             dsp.lpIQ_bw = lpIQ_bw;  // 7.4e3 (6e3..8e3) // IF lowpass bandwidth
             dsp.lpFM_bw = 6e3; // FM audio lowpass
diff --git a/demod/mod/rs92mod.c b/demod/mod/rs92mod.c
index 98c9e3e..03e3f0c 100644
--- a/demod/mod/rs92mod.c
+++ b/demod/mod/rs92mod.c
@@ -1237,6 +1237,7 @@ int main(int argc, char *argv[]) {
     int option_der = 0;    // linErr
     int option_min = 0;
     int option_iq = 0;
+    int option_iqdc = 0;
     int option_lp = 0;
     int option_dc = 0;
     int option_softin = 0;
@@ -1411,6 +1412,7 @@ int main(int argc, char *argv[]) {
         else if   (strcmp(*argv, "--iq0") == 0) { option_iq = 1; }  // differential/FM-demod
         else if   (strcmp(*argv, "--iq2") == 0) { option_iq = 2; }
         else if   (strcmp(*argv, "--iq3") == 0) { option_iq = 3; }  // iq2==iq3
+        else if   (strcmp(*argv, "--iqdc") == 0) { option_iqdc = 1; }  // iq-dc removal (iq0,2,3)
         else if   (strcmp(*argv, "--IQ") == 0) { // fq baseband -> IF (rotate from and decimate)
             double fq = 0.0;                     // --IQ <fq> , -0.5 < fq < 0.5
             ++argv;
@@ -1533,6 +1535,7 @@ int main(int argc, char *argv[]) {
         dsp.BT = 0.5; // bw/time (ISI) // 0.3..0.5
         dsp.h = 0.8; // 1.0 modulation index abzgl. BT
         dsp.opt_iq = option_iq;
+        dsp.opt_iqdc = option_iqdc;
         dsp.opt_lp = option_lp;
         dsp.lpIQ_bw = 8e3; // IF lowpass bandwidth
         dsp.lpFM_bw = 6e3; // FM audio lowpass