Hi all,
thank you for reading this.
I've been trying to use the FDMDV modem 1600 to transmit data. Meaning I
altered the code slightly to transmit a text message. I am transmitting
characters instead of the codec2 bits which are sent to the modulator.
Enclosed is a text document with the source code for the functions used.
On the other end I do actually see the text but instead it is all jumbled
up.
So I am repetitively transmitting this for example:
"CQ-CQ-This_9H5JF_NINE_HOTEL_FIVE_JULIETT_FOXTROT,_CALLING_CQ_AND_STANDING
BY."
On the other side is the a signalink and an altered FreeDV program. The
FreeDV program features an additional text panel where the
f-packed_codec_bits are being copied to an external unsigned char *
malloced space.
Instead of the sentence as is I am getting something like this:
BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BY___aND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYcQ-CQ-cQ-C___aND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-BYaND-
Any help is really appreciated.
Many thanks,
-
//---------------------------------------------------
//
// Snippet from SM1000 code (modified)
//
//---------------------------------------------------
/* Acknowledge switch events */
switch_ack(&sw_select);
switch_ack(&sw_back);
switch_ack(&sw_ptt);
switch (core_state) {
case STATE_MENU:
if (!menuLEDTicker) {
led_pwr(LED_INV);
menuLEDTicker = MENU_LED_PERIOD;
}
break;
case STATE_TX:
/* Transmit
-------------------------------------------------------------------------*/
/* ADC2 is the SM1000 microphone, DAC1 is the modulator signal we send
to radio tx */
if (adc2_read(&adc16k[FDMDV_OS_TAPS_16K], n_samples_16k) == 0) {
GPIOE->ODR = (1 << 3);
/* clipping indicator */
for (i=0; i<n_samples_16k; i++) {
if (abs(adc16k[FDMDV_OS_TAPS_16K+i]) > 28000)
led_err(1);
}
fdmdv_16_to_8_short(adc8k, &adc16k[FDMDV_OS_TAPS_16K],
n_samples);
// Additional code for trying a simple data transmission
// #ifdef RDIO_DATA_TEST
if (op_mode == DATA){
led_rt(1);
led_err(1);
switch(data_text_ctr% NO_DATA_TEXTS){
case(10) :
uchar_ptr = data_text_B;
break;
case(9) :
uchar_ptr = data_text_A;
break;
case(8) :
uchar_ptr = data_text_9;
break;
case(7) :
uchar_ptr = data_text_8;
break;
case(6) :
uchar_ptr = data_text_7;
break;
case(5) :
uchar_ptr = data_text_6;
break;
case(4) :
uchar_ptr = data_text_5;
break;
case(3) :
uchar_ptr = data_text_4;
break;
case(2) :
uchar_ptr = data_text_3;
break;
case(1) :
uchar_ptr = data_text_2;
break;
case(0) :
uchar_ptr = data_text_1;
break;
}
if((counter % 10) == 0){
data_text_ctr++;
}
if(counter < 11){
counter++;
int char_num = sizeof(uchar_ptr)/sizeof(uchar_ptr[0]);
*(off) = 0;
jak_origmod_freedv_comptx_fdmdv_1600(f,&dac8k[FDMDV_OS_TAPS_8K],uchar_ptr,char_num,
off);
for(i=0; i<n_samples; i++)
dac8k[FDMDV_OS_TAPS_8K+i] *= 0.398; /* 8dB back off from peak */
fdmdv_8_to_16_short(dac16k, &dac8k[FDMDV_OS_TAPS_8K], n_samples);
dac1_write(dac16k, n_samples_16k);
}
//-----------------------------------------------------
//
// FreeDV Function
//
//-----------------------------------------------------
#ifdef JAK_FUNCTIONS
void jak_data_fdmdv_mod_1600(struct freedv *f, short mod_out1[], unsigned char
* mod_in, int char_num,int* off){
int bit, byte, i, j;
int bits_per_codec_frame, bits_per_modem_frame;
int data, codeword1, data_flag_index;
COMP tx_fdm[f->n_nat_modem_samples];
// Jak Edit
COMP mod_out[f->n_nat_modem_samples];
// Jak Edit
bits_per_codec_frame = codec2_bits_per_frame(f->codec2);
bits_per_modem_frame = fdmdv_bits_per_frame(f->fdmdv);
/* unpack bits, MSB first */
int num_chars_codec_frame = bits_per_codec_frame / 8;
int offset = 0;
bit = 7; byte = 0;
offset = *(off);
for (i = 0; i<bits_per_codec_frame; i++) {
mod_out1[i] = (mod_in[byte + *(off)] >> bit) & 0x1;
bit--;
if (bit < 0) {
bit = 7;
byte++;
}
}
// Rollover and retransmit string
if (*(off)< char_num)
(*(off)) += num_chars_codec_frame;
else
*(off) = 0;
fdmdv_mod(f->fdmdv, tx_fdm, f->tx_bits, &f->tx_sync_bit);
assert(f->tx_sync_bit == 1);
fdmdv_mod(f->fdmdv, &tx_fdm[FDMDV_NOM_SAMPLES_PER_FRAME],
&f->tx_bits[bits_per_modem_frame], &f->tx_sync_bit);
assert(f->tx_sync_bit == 0);
assert(2 * FDMDV_NOM_SAMPLES_PER_FRAME == f->n_nom_modem_samples);
for (i = 0; i<f->n_nom_modem_samples; i++)
mod_out[i] = fcmult(FDMDV_SCALE, tx_fdm[i]);
for (i = 0; i<f->n_nom_modem_samples; i++)
mod_out1[i] = mod_out[i].real;
}
#endif JAK_FUNCTIONS
------------------------------------------------------------------------------
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