diff --git a/fsk_minitel.c b/fsk_minitel.c
new file mode 100644
index 0000000..7377df1
--- /dev/null
+++ b/fsk_minitel.c
@@ -0,0 +1,627 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <math.h>
+
+#define __cplusplus__strings__
+#ifndef M_PI
+#define M_PI 3.14159265358979324
+#endif
+
+#include <sndfile.h>
+
+//#if defined(WITH_SPANDSP_INTERNALS)
+#define SPANDSP_EXPOSE_INTERNAL_STRUCTURES
+//#endif
+
+#include "my_fsk.h"
+#include "spandsp.h"
+#include "spandsp-sim.h"
+int16_t tone_amp[160];
+int tone_pos=0;
+
+typedef struct
+{
+  double x, y;
+} tComplex;
+
+tComplex complexAdd(const tComplex* a, const tComplex* b)
+{
+  tComplex c;
+  c.x = a->x + b->x;
+  c.y = a->y + b->y;
+  return c;
+}
+
+tComplex complexMul(const tComplex* a, const tComplex* b)
+{
+  tComplex c;
+  c.x = a->x * b->x - a->y * b->y;
+  c.y = a->x * b->y + a->y * b->x;
+  return c;
+}
+
+void dft(tComplex out[], const tComplex in[], size_t n, int direction)
+{
+  size_t k, i;
+  for (k = 0; k < n; k++)
+  {
+    tComplex r = { 0, 0 }, e;
+    for (i = 0; i < n; i++)
+    {
+      e.x = cos(-2 * direction * M_PI / n * ((double)k - n / 2) * ((double)i - n / 2));
+      e.y = sin(-2 * direction * M_PI / n * ((double)k - n / 2) * ((double)i - n / 2));
+      e = complexMul(&e, &in[i]);
+      r = complexAdd(&r, &e);
+    }
+    out[k] = r;
+  }
+}
+
+#define FILTER_LENGTH 64
+void TxInit(tTx* pTx,
+            uint SampleRate,
+            uint (*pTxGetDataCallBack)(tTx*, uint8*))
+{
+  memset(pTx, 0, sizeof(*pTx));
+  pTx->State = stSendingOnes;
+  pTx->SampleRate = SampleRate;
+  pTx->OnesFreq = 1300;
+  pTx->ZeroesFreq = 2100;
+  pTx->BitRate = 1200;
+  pTx->pTxGetDataCallBack = pTxGetDataCallBack;
+
+  pTx->SampleCnt = 0;
+  pTx->BitSampleCnt = pTx->SampleRate;
+  pTx->Data = 0;
+  pTx->DataLeft = 0;
+  pTx->Phase = 0.0;
+  pTx->PhaseIncrement = 2 * M_PI * pTx->OnesFreq / pTx->SampleRate;
+  pTx->queue =  queue_init(NULL, 128, QUEUE_READ_ATOMIC | QUEUE_WRITE_ATOMIC);
+}
+
+int16 TxGetSample(tTx* pTx)
+{
+  int16 sample; 
+  float sample1, sample2, mixed;
+
+  if (pTx->State == stSendingOnes &&
+      pTx->SampleCnt >= pTx->SampleRate)
+  {
+    // Sent 1 second worth of 1's, can now send data
+    pTx->State = stSendingData;
+  }
+
+  if (pTx->State == stSendingData &&
+      pTx->BitSampleCnt >= pTx->SampleRate)
+  {
+    // Another data bit can now be sent
+    uint8 d;
+
+    pTx->BitSampleCnt -= pTx->SampleRate;
+
+    if (!pTx->DataLeft)
+    {
+      // Get the next data byte (if any)
+      if (pTx->pTxGetDataCallBack(pTx, &d) != 0)
+      {
+        pTx->Data = d & 0x7F;
+        pTx->Data |= (__builtin_popcount( d & 0x7F ) & 1) << 7; // insert parity
+        pTx->Data |= 1 << 8; // insert the stop bit
+        pTx->Data <<= 1; // insert the start bit
+        pTx->DataLeft = 10;
+      }
+      else
+      {
+        pTx->Data = 0x3FF; // no data, send 10 1's
+        pTx->DataLeft = 10;
+      }
+    }
+
+    // Extract the next data bit to send
+    d = pTx->Data & 1;
+    pTx->Data >>= 1;
+    pTx->DataLeft--;
+
+    // Choose the appropriate frequency for 0 and 1
+    if (d)
+    {
+      pTx->PhaseIncrement = 2 * M_PI * pTx->OnesFreq / pTx->SampleRate;
+    }
+    else
+    {
+      pTx->PhaseIncrement = 2 * M_PI * pTx->ZeroesFreq / pTx->SampleRate;
+    }
+  }
+
+  // Generate the next sample, advance the generator's phase
+  sample = (int16)(16000 * cos(pTx->Phase));
+  pTx->Phase += pTx->PhaseIncrement;
+  if (pTx->Phase >= 2 * M_PI)
+  {
+    pTx->Phase -= 2 * M_PI;
+  }
+
+  if (pTx->State == stSendingData)
+  {
+    pTx->BitSampleCnt += pTx->BitRate;
+  }
+
+  pTx->SampleCnt++;
+  
+  /*Mix tone*/
+  sample1 = sample / 32768.0f;
+  sample2 = tone_amp[tone_pos%sizeof(tone_amp)] / 32768.0f;
+  mixed = sample1+sample2;
+  mixed *= 0.75;
+  if (mixed > 1.0f) { mixed = 1.0f ;printf("clip\n"); }
+  if (mixed < -1.0f){mixed = -1.0f; printf("clip\n"); }
+  
+  tone_pos++;
+  return (uint16_t)(mixed * 32768.0f);
+
+}
+
+void RxInit(tRx* pRx,
+            uint SampleRate,
+            void (*pRxGetDataCallBack)(struct tRx*, uint8))
+{
+  tComplex tmp[FILTER_LENGTH];
+  uint i;
+
+  memset(pRx, 0, sizeof(*pRx));
+  pRx->State = stCarrierLost;
+  pRx->SampleRate = SampleRate;
+  pRx->OnesFreq = 1300;
+  pRx->ZeroesFreq = 2100;
+  pRx->MidFreq = (pRx->OnesFreq + pRx->ZeroesFreq) / 2;
+  pRx->BitRate = 1200;
+  pRx->pRxGetDataCallBack = pRxGetDataCallBack;
+
+  pRx->SampleCnt = 0;
+  pRx->BitSampleCnt = 0;
+  pRx->Data = 0x3FF;
+  pRx->Phase = 0.0;
+  pRx->PhaseIncrement = 2 * M_PI * pRx->MidFreq / pRx->SampleRate;
+  pRx->LastAngle = 0.0;
+  pRx->LastDelta = 0;
+  pRx->Deltas = 0;
+  pRx->CarrierAngle = 0;
+  pRx->CarrierCnt = 0;
+  pRx->LongAvgPower = 0.0;
+  pRx->ShortAvgPower = 0.0;
+  pRx->queue = queue_init(rx->queue, 128, QUEUE_READ_ATOMIC | QUEUE_WRITE_ATOMIC);
+  
+  for (i = 0; i < FILTER_LENGTH; i++)
+  {
+    pRx->Delay[i] = 0.0;
+  }
+
+  for (i = 0; i < FILTER_LENGTH; i++)
+  {
+    if (i == 0) // w < 0 (min w)
+    {
+      pRx->Filter[i].x = 0;
+      pRx->Filter[i].y = 0;
+    }
+    else if (i < FILTER_LENGTH / 2) // w < 0
+    {
+      pRx->Filter[i].x = 0;
+      pRx->Filter[i].y = 0;
+    }
+    else if (i == FILTER_LENGTH / 2) // w = 0
+    {
+      pRx->Filter[i].x = 0;
+      pRx->Filter[i].y = 0;
+    }
+    else if (i > FILTER_LENGTH / 2) // w > 0
+    {
+      pRx->Filter[i].x = 0;
+      pRx->Filter[i].y = -1;
+
+      // Extra filter to combat channel noise
+      if (i - FILTER_LENGTH / 2 < 875UL * FILTER_LENGTH / pRx->SampleRate ||
+          i - FILTER_LENGTH / 2 > (2350UL * FILTER_LENGTH + pRx->SampleRate - 1) / pRx->SampleRate)
+      {
+        pRx->Filter[i].y = 0;
+      }
+    }
+  }
+
+  memcpy(tmp, pRx->Filter, sizeof(tmp));
+  dft(pRx->Filter, tmp, FILTER_LENGTH, -1);
+}
+
+#define RX_VERBOSE 0
+void RxGetSample(tRx* pRx, int16 Sample)
+{
+  tComplex s = { 0.0, 0.0 }, ss;
+  double angle;
+  uint i;
+  int delta;
+  double pwr;
+
+  // Insert the sample into the delay line
+  memmove(&pRx->Delay[0], &pRx->Delay[1], sizeof(pRx->Delay) - sizeof(pRx->Delay[0]));
+  pRx->Delay[FILTER_LENGTH - 1] = Sample;
+
+  // Get the next analytic signal sample by applying Hilbert transform/filter
+  for (i = 0; i < FILTER_LENGTH; i++)
+  {
+    s.x += pRx->Delay[i] * pRx->Filter[FILTER_LENGTH - 1 - i].x;
+    s.y += pRx->Delay[i] * pRx->Filter[FILTER_LENGTH - 1 - i].y;
+  }
+
+  // Frequency shift by MidFreq down
+  ss.x = cos(-pRx->Phase);
+  ss.y = sin(-pRx->Phase);
+  s = complexMul(&s, &ss);
+  pRx->Phase += pRx->PhaseIncrement;
+  if (pRx->Phase >= 2 * M_PI)
+  {
+    pRx->Phase -= 2 * M_PI;
+  }
+
+  // Calculate signal power
+  pwr = (s.x * s.x + s.y * s.y) / 32768 / 32768;
+  pRx->LongAvgPower *= 1 - pRx->BitRate / (pRx->SampleRate * 8.0 * 8);
+  pRx->LongAvgPower += pwr;
+  pRx->ShortAvgPower *= 1 - pRx->BitRate / (pRx->SampleRate * 8.0);
+  pRx->ShortAvgPower += pwr;
+
+#if 0
+  printf("LongAvgPower:%f ShortAvgPower:%f\n", pRx->LongAvgPower, pRx->ShortAvgPower);
+#endif
+
+  // Disconnect if the signal power changes abruptly.
+  if (pRx->State != stCarrierLost &&
+      pRx->LongAvgPower > pRx->ShortAvgPower * 8 * 8)
+  {
+    // N.B. The receiver may have received a few extra (garbage) bytes
+    // while demodulating the abruptly changed signal.
+    // Prefixing data with its size or using a more advanced protocol
+    // may be a good solution to this little problem.
+    pRx->State = stCarrierLost;
+    pRx->BitSampleCnt = 0;
+    pRx->Data = 0x3FF;
+    pRx->Phase = 0.0;
+    pRx->LastAngle = 0.0;
+    pRx->LastDelta = 0;
+    pRx->Deltas = 0;
+    pRx->CarrierAngle = 0;
+    pRx->CarrierCnt = 0;
+  }
+
+  // Get the phase angle from the analytic signal sample
+  angle = (fpclassify(s.x) == FP_ZERO && fpclassify(s.y) == FP_ZERO) ?
+    0.0 : 180 / M_PI * atan2(s.y, s.x);
+  // Calculate the phase angle change and force it to the -PI to +PI range
+  delta = (int)(360.5 + angle - pRx->LastAngle) % 360;
+  if (delta > 180) delta -= 360;
+
+  if (pRx->State == stCarrierLost)
+  {
+    // Accumulate the phase angle change to see if we're receiving 1's
+    pRx->CarrierAngle += delta;
+    pRx->CarrierCnt++;
+
+    // Check whether or not the phase corresponds to 1's
+    if (delta < 0)
+    {
+      if (pRx->CarrierCnt >= pRx->SampleRate / pRx->OnesFreq * 8)
+      {
+        double ph = (double)pRx->CarrierAngle / pRx->CarrierCnt;
+#if RX_VERBOSE
+        printf("ca:%5ld, cc:%4ld, ca/cc:%4ld\n",
+               (long)pRx->CarrierAngle,
+               (long)pRx->CarrierCnt,
+               (long)(pRx->CarrierAngle / pRx->CarrierCnt));
+#endif
+        // Frequency tolerance is +/-16 Hz per the V.23 spec
+        if (ph < (pRx->OnesFreq - 17.0 - pRx->MidFreq) * 360.0 / pRx->SampleRate ||
+            ph > (pRx->OnesFreq + 17.0 - pRx->MidFreq) * 360.0 / pRx->SampleRate)
+        {
+          goto BadCarrier;
+        }
+      }
+    }
+    else
+    {
+BadCarrier:
+      // Phase doesn't correspond to 1's
+      pRx->CarrierAngle = 0.0;
+      pRx->CarrierCnt = 0;
+    }
+
+    if (pRx->CarrierCnt >= pRx->SampleRate / 2 + pRx->SampleRate / 4)
+    {
+      // 0.75 seconds worth of 1's have been detected, ready to receive data
+
+      // Adjust MidFreq to compensate for the DAC and ADC sample rate difference
+      double f1 = (double)pRx->CarrierAngle / pRx->CarrierCnt / 360 * pRx->SampleRate + pRx->MidFreq;
+      pRx->MidFreq = (uint)(pRx->MidFreq * f1 / pRx->OnesFreq);
+      pRx->PhaseIncrement = 2 * M_PI * pRx->MidFreq / pRx->SampleRate;
+#if RX_VERBOSE
+      printf("f1:%u, new MidFreq:%u\n", (uint)f1, pRx->MidFreq);
+#endif
+      pRx->State = stCarrierDetected;
+    }
+  }
+  else
+  {
+    // Detect frequency changes (transitions between 0's and 1's)
+    int freqChange = ((int32)pRx->LastDelta * delta < 0 || pRx->LastDelta && !delta);
+    int reAddDelta = 0;
+
+#if RX_VERBOSE
+    printf("%6lu: delta:%4d freqChange:%d BitSampleCnt:%u\n",
+           (ulong)pRx->SampleCnt,
+           delta,
+           freqChange,
+           pRx->BitSampleCnt);
+#endif
+
+    // Synchronize with 1<->0 transitions
+    if (freqChange)
+    {
+      if (pRx->BitSampleCnt >= pRx->SampleRate / 2)
+      {
+        pRx->BitSampleCnt = pRx->SampleRate;
+        pRx->Deltas -= delta;
+        reAddDelta = 1;
+      }
+      else
+      {
+        pRx->BitSampleCnt = 0;
+        pRx->Deltas = 0;
+      }
+    }
+
+    // Accumulate analytic signal phase angle changes
+    // (positive for 0, negative for 1)
+    pRx->Deltas += delta;
+
+    if (pRx->BitSampleCnt >= pRx->SampleRate)
+    {
+      // Another data bit has accumulated
+      pRx->BitSampleCnt -= pRx->SampleRate;
+
+#if RX_VERBOSE
+      printf("bit: %u\n", pRx->Deltas < 0);
+#endif
+
+      pRx->Data >>= 1;
+      pRx->Data |= (pRx->Deltas < 0) << 9;
+      pRx->Deltas = delta * reAddDelta;
+
+      if ((pRx->Data & 0x201) == 0x200)
+      {
+        // Start and stop bits have been detected
+        if (pRx->State == stCarrierDetected)
+        {
+          pRx->State = stReceivingData;
+        }
+        pRx->Data = (pRx->Data >> 1) & 0x7F;
+        pRx->pRxGetDataCallBack(pRx, (uint8)pRx->Data);
+
+#if RX_VERBOSE
+        printf("byte: 0x%02X ('%c')\n",
+               pRx->Data,
+               (pRx->Data >= 0x20 && pRx->Data <= 0x7F) ? pRx->Data : '?');
+#endif
+
+        pRx->Data = 0x3FF;
+      }
+    }
+
+    pRx->BitSampleCnt += pRx->BitRate;
+  }
+
+  pRx->LastAngle = angle;
+  pRx->LastDelta = delta;
+  pRx->SampleCnt++;
+}
+
+typedef struct
+{
+  tTx Tx;
+  FILE* DataFile;
+  int CountDown;
+} tTxTest;
+
+uint TxGetDataCallBack(tTx* pTx, uint8* pTxData)
+{
+  tTxTest* pTxTest = (tTxTest*)pTx;
+  uchar c;
+
+  if (pTxTest->CountDown)
+  {
+    pTxTest->CountDown--;
+    return 0;
+  }
+  /*
+  if (fread(&c, 1, 1, pTxTest->DataFile) != 1)
+  {
+    pTxTest->CountDown = 20;
+    return 0;
+  }
+ */
+ if( ! queue_empty(pTx->queue)){
+    c =  queue_read_byte(pTx->queue);
+    pTxTest->CountDown = 20;
+   }
+  *pTxData = c;
+  return 1;
+}
+
+int testTx(uint SampleRate,
+           double NoiseLevel,
+           const char* DataFileName,
+           const char* AudioFileName)
+{
+  FILE *fData = NULL;
+  SNDFILE *fAudio = NULL;
+  //FILE *fAudio = NULL;
+  tone_gen_descriptor_t t_desc;
+  tone_gen_state_t t_state;
+    
+  int err = EXIT_FAILURE;
+  tTxTest txTest;
+
+  if ((fData = fopen(DataFileName, "rb")) == NULL)
+  {
+    printf("Can't open file \"%s\"\n", DataFileName);
+    goto Exit;
+  }
+
+  tone_gen_descriptor_init(&t_desc, 1300, -12.0, 0, 0,20, 0, 0, 0, 0);
+
+  tone_gen_init(&t_state, &t_desc);
+  tone_gen(&t_state, tone_amp, sizeof(tone_amp));
+
+ if ((fAudio = sf_open_telephony_write(AudioFileName, 1)) == NULL)  
+// if ((fAudio = fopen(AudioFileName, "wb")) == NULL)  
+{
+    printf("Can't create file \"%s\"\n", AudioFileName);
+    goto Exit;
+  }
+
+  txTest.DataFile = fData;
+  txTest.CountDown = 0;
+
+  TxInit(&txTest.Tx,
+         SampleRate,
+         &TxGetDataCallBack);
+
+  do
+  {
+    int16 sample = TxGetSample(&txTest.Tx);
+    if (txTest.CountDown > 1 && txTest.CountDown <= 10)
+    {
+#if 0 // Enable this code to test disconnecting.
+      // Finish with silence.
+      
+#endif
+    }
+    //sample += (rand() - (int)RAND_MAX / 2) * NoiseLevel * 16000 / (RAND_MAX / 2);
+    sf_writef_short(fAudio, &sample, 1);
+    //fwrite(&sample, 1, sizeof(sample), fAudio);
+  } while (txTest.CountDown != 1); // Drain all data-containing samples
+
+  err = EXIT_SUCCESS;
+
+Exit:
+
+  if (fData != NULL) fclose(fData);
+  if (fAudio != NULL)
+	sf_close(fAudio);
+//	 fclose(fAudio);
+
+  return err;
+}
+
+typedef struct
+{
+  tRx Rx;
+  FILE* DataFile;
+} tRxTest;
+
+void RxGetDataCallBack(tRx* pRx, uint8 RxData)
+{
+  tRxTest* pRxTest = (tRxTest*)pRx;
+  uchar c = RxData;
+  if (queue_free_space(pRx->queue)){
+     queue_write_byte(pRx->queue, (uint16_t)Rxdata); 
+  }
+  //fwrite(&c, 1, 1, pRxTest->DataFile);
+}
+
+int testRx(uint SampleRate,
+           const char* AudioFileName,
+           const char* DataFileName)
+{
+  uint lastState;
+  int err = EXIT_FAILURE;
+  tRxTest rxTest;
+
+
+  RxInit(&rxTest.Rx,
+         8000,//SampleRate,
+         &RxGetDataCallBack);
+
+  for (;;)
+  {
+    int16 sample;
+
+    if (fread(&sample, 1, sizeof(sample), fAudio) != sizeof(sample))
+    {
+      if (rxTest.Rx.State != stCarrierLost) goto NoCarrier;
+      break;
+    }
+
+    lastState = rxTest.Rx.State;
+    RxGetSample(&rxTest.Rx, sample);
+
+    if (rxTest.Rx.State != lastState && rxTest.Rx.State == stCarrierDetected)
+    {
+      printf("\nCONNECT %u\n\n", rxTest.Rx.BitRate);
+    }
+
+    if (rxTest.Rx.State != lastState && rxTest.Rx.State == stCarrierLost)
+    {
+NoCarrier:
+      printf("\n\nNO CARRIER\n");
+      break;
+    }
+  }
+
+  err = EXIT_SUCCESS;
+
+Exit:
+
+  if (fAudio != NULL) fclose(fAudio);
+  if (fData != NULL) fclose(fData);
+
+  return err;
+}
+/*
+int main(int argc, char* argv[])
+{
+  uint sampleRate;
+  double noiseLevel;
+
+  if (argc < 2 ||
+      !strcasecmp(argv[1], "-help") ||
+      !strcasecmp(argv[1], "/help") ||
+      !strcasecmp(argv[1], "-?") ||
+      !strcasecmp(argv[1], "/?"))
+  {
+Usage:
+    printf("Usage:\n\n"
+           "  %s tx <sample rate> <noise level> <data input file> <PCM output file>\n"
+           "  %s rx <sample rate> <PCM input file> <data output file>\n",
+           argv[0],
+           argv[0]);
+    return 0;
+  }
+
+  if (!strcasecmp(argv[1], "tx") &&
+      argc == 6 &&
+      sscanf(argv[2], "%u", &sampleRate) == 1 &&
+      sscanf(argv[3], "%lf", &noiseLevel) == 1)
+  {
+    return testTx(sampleRate, noiseLevel, argv[4], argv[5]);
+  }
+  else if (!strcasecmp(argv[1], "rx") &&
+           argc == 5 &&
+           sscanf(argv[2], "%u", &sampleRate) == 1)
+  {
+    return testRx(sampleRate, argv[3], argv[4]);
+  }
+  else
+  {
+    goto Usage;
+  }
+}
+*/
diff --git a/fsk_minitel.h b/fsk_minitel.h
new file mode 100644
index 0000000..2a6f956
--- /dev/null
+++ b/fsk_minitel.h
@@ -0,0 +1,94 @@
+
+typedef unsigned char uchar, uint8;
+typedef signed char schar, int8;
+typedef unsigned short ushort, uint16;
+typedef short int16;
+typedef unsigned int uint;
+typedef unsigned long ulong;
+#if UINT_MAX >= 0xFFFFFFFF
+typedef int int32;
+typedef unsigned int uint32;
+#else
+typedef long int32;
+typedef unsigned long uint32;
+#endif
+typedef long long int64;
+typedef unsigned long long uint64;
+
+
+typedef struct tTx
+{
+  enum
+  {
+    stSendingOnes,
+    stSendingData
+  } State;
+
+  uint SampleRate;
+  uint OnesFreq;
+  uint ZeroesFreq;
+  uint BitRate;
+
+  uint32 SampleCnt;
+  uint BitSampleCnt;
+  uint Data;
+  uint DataLeft;
+
+  double Phase;
+  double PhaseIncrement;
+
+  queue_state_t *queue;
+  uint (*pTxGetDataCallBack)(struct tTx*, uint8*);
+} tTx;
+
+typedef struct tRx
+{
+  enum
+  {
+    stCarrierLost,
+    stCarrierDetected,
+    stReceivingData
+  } State;
+
+  uint SampleRate;
+  uint OnesFreq;
+  uint ZeroesFreq;
+  uint MidFreq;
+  uint BitRate;
+
+  uint32 SampleCnt;
+  uint BitSampleCnt;
+  uint Data;
+
+  double Phase;
+  double PhaseIncrement;
+
+  tComplex Filter[FILTER_LENGTH];
+  double Delay[FILTER_LENGTH];
+
+  double LastAngle;
+  int LastDelta;
+  int32 Deltas;
+
+  int32 CarrierAngle;
+  int32 CarrierCnt;
+
+  double LongAvgPower;
+  double ShortAvgPower;
+  queue_state_t *queue;
+  void (*pRxGetDataCallBack)(struct tRx*, uint8);
+} tRx;
+
+
+void TxInit(tTx* pTx,
+            uint SampleRate,
+            uint (*pTxGetDataCallBack)(tTx*, uint8*));
+
+int16 TxGetSample(tTx* pTx);
+
+void RxInit(tRx* pRx,
+            uint SampleRate,
+            void (*pRxGetDataCallBack)(struct tRx*, uint8));
+
+void RxGetSample(tRx* pRx, int16 Sample);
+