diff --git a/auto_rx/autorx/__init__.py b/auto_rx/autorx/__init__.py
index e364e7b..a12f9ee 100644
--- a/auto_rx/autorx/__init__.py
+++ b/auto_rx/autorx/__init__.py
@@ -12,7 +12,7 @@ from queue import Queue
 # MINOR - New sonde type support, other fairly big changes that may result in telemetry or config file incompatability issus.
 # PATCH - Small changes, or minor feature additions.
 
-__version__ = "1.6.0-beta12"
+__version__ = "1.6.0-beta13"
 
 
 # Global Variables
diff --git a/demod/mod/demod_mod.c b/demod/mod/demod_mod.c
index 0b1dc0c..38d8f5c 100644
--- a/demod/mod/demod_mod.c
+++ b/demod/mod/demod_mod.c
@@ -618,17 +618,17 @@ static int lowpass_update(float f, int taps, float *ws) {
 }
 
 static float complex lowpass0(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
-    ui32_t n;
+    ui32_t n;            // sample: oldest_sample
     double complex w = 0;
     for (n = 0; n < taps; n++) {
-        w += buffer[(sample+n+1)%taps]*ws[taps-1-n];
+        w += buffer[(sample+n)%taps]*ws[taps-1-n];
     }
     return (float complex)w;
 }
 static float complex lowpass1a(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
     double complex w = 0;
     ui32_t n;
-    ui32_t S = taps + (sample % taps);
+    ui32_t S = taps-1 + (sample % taps);
     for (n = 0; n < taps; n++) {
         w += buffer[n]*ws[S-n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
     }
@@ -639,7 +639,7 @@ static float complex lowpass1a(float complex buffer[], ui32_t sample, ui32_t tap
 static float complex lowpass(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
     float complex w = 0;
     int n; // -Ofast
-    int S = taps-1 - (sample % taps);
+    int S = taps - (sample % taps);
     for (n = 0; n < taps; n++) {
         w += buffer[n]*ws[S+n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
     }
@@ -650,9 +650,9 @@ static float complex lowpass2(float complex buffer[], ui32_t sample, ui32_t taps
     float complex w = 0;
     int n; // -Ofast
     int s = sample % taps;
-    int S1 = s+1;
+    int S1 = s;
     int S1N = S1-taps;
-    int n0 = taps-1-s;
+    int n0 = taps-s;
     for (n = 0; n < n0; n++) {
         w += buffer[S1+n]*ws[n];
     }
@@ -664,16 +664,16 @@ static float complex lowpass2(float complex buffer[], ui32_t sample, ui32_t taps
 }
 static float complex lowpass0_sym(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
     ui32_t n;
-    double complex w = buffer[(sample+(taps+1)/2) % taps]*ws[(taps-1)/2]; // (N+1)/2 = (N-1)/2 + 1
+    double complex w = buffer[(sample+(taps-1)/2) % taps]*ws[(taps-1)/2]; // (N+1)/2 = (N-1)/2 + 1
     for (n = 0; n < (taps-1)/2; n++) {
-        w += (buffer[(sample+n+1)%taps]+buffer[(sample+taps-n)%taps])*ws[n];
+        w += (buffer[(sample+n)%taps]+buffer[(sample+taps-n-1)%taps])*ws[n];
     }
     return (float complex)w;
 }
 static float complex lowpass2_sym(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
     float complex w = 0;
     int n;
-    int s = (sample+1) % taps; // lpIQ
+    int s = sample % taps; // lpIQ
     int SW = (taps-1)/2;
     int B1 = s + SW;
     int n1 = SW - s;
@@ -704,18 +704,18 @@ static float re_lowpass0(float buffer[], ui32_t sample, ui32_t taps, float *ws)
     ui32_t n;
     double w = 0;
     for (n = 0; n < taps; n++) {
-        w += buffer[(sample+n+1)%taps]*ws[taps-1-n];
+        w += buffer[(sample+n)%taps]*ws[taps-1-n];
     }
     return (float)w;
 }
 static float re_lowpass(float buffer[], ui32_t sample, ui32_t taps, float *ws) {
-    ui32_t n;
-    ui32_t s = sample % taps;
-    double w = 0;
+    float w = 0;
+    int n;
+    int S = taps - (sample % taps);
     for (n = 0; n < taps; n++) {
-        w += buffer[n]*ws[taps+s-n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
+        w += buffer[n]*ws[S+n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
     }
-    return (float)w;
+    return w;
 }
 
 
@@ -750,7 +750,7 @@ int f32buf_sample(dsp_t *dsp, int inv) {
             }
             if (dsp->decM > 1)
             {
-                z = lowpass(dsp->decXbuffer, dsp->sample_decX, dsp->dectaps, ws_dec);
+                z = lowpass(dsp->decXbuffer, dsp->sample_decX, dsp->dectaps, ws_dec); // oldest sample: dsp->sample_decX
             }
         }
         else if ( f32read_csample(dsp, &z) == EOF ) return EOF;
@@ -764,7 +764,7 @@ int f32buf_sample(dsp_t *dsp, int inv) {
         // IF-lowpass
         if (dsp->opt_lp & LP_IQ) {
             dsp->lpIQ_buf[dsp->sample_in % dsp->lpIQtaps] = z;
-            z = lowpass(dsp->lpIQ_buf, dsp->sample_in, dsp->lpIQtaps, dsp->ws_lpIQ);
+            z = lowpass(dsp->lpIQ_buf, dsp->sample_in+1, dsp->lpIQtaps, dsp->ws_lpIQ);
         }
 
 
@@ -842,7 +842,7 @@ int f32buf_sample(dsp_t *dsp, int inv) {
     // FM-lowpass
     if (dsp->opt_lp & LP_FM) {
         dsp->lpFM_buf[dsp->sample_in % dsp->lpFMtaps] = s_fm;
-        s_fm = re_lowpass(dsp->lpFM_buf, dsp->sample_in, dsp->lpFMtaps, dsp->ws_lpFM);
+        s_fm = re_lowpass(dsp->lpFM_buf, dsp->sample_in+1, dsp->lpFMtaps, dsp->ws_lpFM);
         if (dsp->opt_iq < 2) s = s_fm;
     }
 
diff --git a/imet/imet4iq.c b/imet/imet4iq.c
index 9c82e3d..b96d432 100644
--- a/imet/imet4iq.c
+++ b/imet/imet4iq.c
@@ -397,7 +397,7 @@ static int lowpass_init(float f, int taps, float **pws) {
 static float complex lowpass1a(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
     double complex w = 0;
     ui32_t n;
-    ui32_t S = taps + (sample % taps);
+    ui32_t S = taps-1 + (sample % taps);
     for (n = 0; n < taps; n++) {
         w += buffer[n]*ws[S-n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
     }
@@ -408,7 +408,7 @@ static float complex lowpass1a(float complex buffer[], ui32_t sample, ui32_t tap
 static float complex lowpass(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
     float complex w = 0;
     int n; // -Ofast
-    int S = taps-1 - (sample % taps);
+    int S = taps - (sample % taps);
     for (n = 0; n < taps; n++) {
         w += buffer[n]*ws[S+n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
     }
@@ -419,9 +419,9 @@ static float complex lowpass2(float complex buffer[], ui32_t sample, ui32_t taps
     float complex w = 0;     // -Ofast
     int n;
     int s = sample % taps; // lpIQ
-    int S1 = s+1;
+    int S1 = s;
     int S1N = S1-taps;
-    int n0 = taps-1-s;
+    int n0 = taps-s;
     for (n = 0; n < n0; n++) {
         w += buffer[S1+n]*ws[n];
     }
@@ -433,13 +433,13 @@ static float complex lowpass2(float complex buffer[], ui32_t sample, ui32_t taps
 }
 
 static float re_lowpass(float buffer[], ui32_t sample, ui32_t taps, float *ws) {
-    ui32_t n;
-    ui32_t s = sample % taps;
-    double w = 0;
+    float w = 0;
+    int n;
+    int S = taps - (sample % taps);
     for (n = 0; n < taps; n++) {
-        w += buffer[n]*ws[taps+s-n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
+        w += buffer[n]*ws[S+n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
     }
-    return (float)w;
+    return w;
 }
 
 static
@@ -498,7 +498,7 @@ int f32_sample(dsp_t *dsp, float *out) {
             // IF-lowpass
             if (dsp->opt_lp & LP_IQ) {
                 dsp->lpIQ_buf[_sample % dsp->lpIQtaps] = z;
-                z = lowpass(dsp->lpIQ_buf, _sample, dsp->lpIQtaps, dsp->ws_lpIQ);
+                z = lowpass(dsp->lpIQ_buf, _sample+1, dsp->lpIQtaps, dsp->ws_lpIQ);
             }
 
 
@@ -520,7 +520,7 @@ int f32_sample(dsp_t *dsp, float *out) {
         if (dsp->opt_lp & LP_FM) {
             dsp->lpFM_buf[_sample % dsp->lpFMtaps] = s_fm;
             if (m+1 == decFM) {
-                s_fm = re_lowpass(dsp->lpFM_buf, _sample, dsp->lpFMtaps, dsp->ws_lpFM);
+                s_fm = re_lowpass(dsp->lpFM_buf, _sample+1, dsp->lpFMtaps, dsp->ws_lpFM);
                 if (dsp->opt_iq < 2 || dsp->opt_iq > 5) s = s_fm; //opt_iq==0,1,6
             }
         }
diff --git a/mk2a/mk2a1680mod.c b/mk2a/mk2a1680mod.c
index 760f3d4..fc7ad01 100644
--- a/mk2a/mk2a1680mod.c
+++ b/mk2a/mk2a1680mod.c
@@ -735,7 +735,7 @@ static int lowpass_init(float f, int taps, float **pws) {
 static float complex lowpass1a(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
     double complex w = 0;
     ui32_t n;
-    ui32_t S = taps + (sample % taps);
+    ui32_t S = taps-1 + (sample % taps);
     for (n = 0; n < taps; n++) {
         w += buffer[n]*ws[S-n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
     }
@@ -746,7 +746,7 @@ static float complex lowpass1a(float complex buffer[], ui32_t sample, ui32_t tap
 static float complex lowpass(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
     float complex w = 0;
     int n; // -Ofast
-    int S = taps-1 - (sample % taps);
+    int S = taps - (sample % taps);
     for (n = 0; n < taps; n++) {
         w += buffer[n]*ws[S+n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
     }
@@ -757,9 +757,9 @@ static float complex lowpass2(float complex buffer[], ui32_t sample, ui32_t taps
     float complex w = 0;
     int n;
     int s = sample % taps;
-    int S1 = s+1;
+    int S1 = s;
     int S1N = S1-taps;
-    int n0 = taps-1-s;
+    int n0 = taps-s;
     for (n = 0; n < n0; n++) {
         w += buffer[S1+n]*ws[n];
     }
@@ -771,13 +771,13 @@ static float complex lowpass2(float complex buffer[], ui32_t sample, ui32_t taps
 }
 
 static float re_lowpass(float buffer[], ui32_t sample, ui32_t taps, float *ws) {
-    ui32_t n;
-    ui32_t s = sample % taps;
-    double w = 0;
+    float w = 0;
+    int n;
+    int S = taps - (sample % taps);
     for (n = 0; n < taps; n++) {
-        w += buffer[n]*ws[taps+s-n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
+        w += buffer[n]*ws[S+n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
     }
-    return (float)w;
+    return w;
 }
 
 
@@ -835,7 +835,7 @@ int f32buf_sample(dsp_t *dsp, int inv) {
             // IF-lowpass
             if (dsp->opt_lp & LP_IQ) {
                 dsp->lpIQ_buf[_sample % dsp->lpIQtaps] = z;
-                z = lowpass(dsp->lpIQ_buf, _sample, dsp->lpIQtaps, dsp->ws_lpIQ);
+                z = lowpass(dsp->lpIQ_buf, _sample+1, dsp->lpIQtaps, dsp->ws_lpIQ);
             }
 
 
@@ -919,7 +919,7 @@ int f32buf_sample(dsp_t *dsp, int inv) {
         if (dsp->opt_lp & LP_FM) {
             dsp->lpFM_buf[_sample % dsp->lpFMtaps] = s_fm;
             if (m+1 == decFM) {
-                s_fm = re_lowpass(dsp->lpFM_buf, _sample, dsp->lpFMtaps, dsp->ws_lpFM);
+                s_fm = re_lowpass(dsp->lpFM_buf, _sample+1, dsp->lpFMtaps, dsp->ws_lpFM);
                 if (dsp->opt_iq < 2 || dsp->opt_iq > 5) s = s_fm; //opt_iq==0,1,6
             }
         }
@@ -928,7 +928,7 @@ int f32buf_sample(dsp_t *dsp, int inv) {
         if (dsp->opt_lp & LP_IQFM) {  // opt_iq==5
             dsp->lpIQFM_buf[_sample % dsp->lpIQFMtaps] = s;
             if (m+1 == decFM) {
-                s = re_lowpass(dsp->lpIQFM_buf, _sample, dsp->lpIQFMtaps, dsp->ws_lpIQFM);
+                s = re_lowpass(dsp->lpIQFM_buf, _sample+1, dsp->lpIQFMtaps, dsp->ws_lpIQFM);
             }
         }
 
diff --git a/scan/dft_detect.c b/scan/dft_detect.c
index 42b32c2..65b2646 100644
--- a/scan/dft_detect.c
+++ b/scan/dft_detect.c
@@ -646,7 +646,7 @@ static float complex lowpass0(float complex buffer[], ui32_t sample, ui32_t taps
     ui32_t n;
     double complex w = 0;
     for (n = 0; n < taps; n++) {
-        w += buffer[(sample+n+1)%taps]*ws[taps-1-n];
+        w += buffer[(sample+n)%taps]*ws[taps-1-n];
     }
     return (float complex)w;
 }
@@ -654,7 +654,7 @@ static float complex lowpass0(float complex buffer[], ui32_t sample, ui32_t taps
 static float complex lowpass(float complex buffer[], ui32_t sample, ui32_t taps, float *ws) {
     float complex w = 0;
     int n; // -Ofast
-    int S = taps-1 - (sample % taps);
+    int S = taps - (sample % taps);
     for (n = 0; n < taps; n++) {
         w += buffer[n]*ws[S+n]; // ws[taps+s-n] = ws[(taps+sample-n)%taps]
     }
@@ -665,9 +665,9 @@ static float complex lowpass2(float complex buffer[], ui32_t sample, ui32_t taps
     float complex w = 0;
     int n;
     int s = sample % taps;
-    int S1 = s+1;
+    int S1 = s;
     int S1N = S1-taps;
-    int n0 = taps-1-s;
+    int n0 = taps-s;
     for (n = 0; n < n0; n++) {
         w += buffer[S1+n]*ws[n];
     }
@@ -711,8 +711,8 @@ static int f32buf_sample(FILE *fp, int inv) {
         // b) 3 FM-streams
         //
         lpIQ_buf[sample_in % dsp__lpIQtaps] = z;
-        z_fm0 = lowpass(lpIQ_buf, sample_in, dsp__lpIQtaps, ws_lpIQ[0]);
-        z_fm1 = lowpass(lpIQ_buf, sample_in, dsp__lpIQtaps, ws_lpIQ[1]);
+        z_fm0 = lowpass(lpIQ_buf, sample_in+1, dsp__lpIQtaps, ws_lpIQ[0]);
+        z_fm1 = lowpass(lpIQ_buf, sample_in+1, dsp__lpIQtaps, ws_lpIQ[1]);
 
         // IQ: different modulation indices h=h(rs) -> FM-demod
         w = z_fm0 * conj(z0_fm0);