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common: Add pre and de emphasis, if the radio does not support it

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Connect to the oscillator of the transmitter - good girl!
You need to enable pre emphasis in this case.

Connect to the discriminator of the receiver - good boy!
You need to enable de emphasis in this case.
This commit is contained in:
Andreas Eversberg
2016-04-23 18:50:11 +02:00
parent 5062628e52
commit 4356c93afa
20 changed files with 256 additions and 19 deletions
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5
src/nmt/dsp.c
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@@ -33,7 +33,7 @@
#define PI M_PI
/* signalling */
#define TX_AUDIO_0dBm0 16384 /* works quite well */
#define TX_AUDIO_0dBm0 32767 /* works quite well */
#define TX_PEAK_FSK 16384.0 /* peak amplitude of signalling FSK */
#define TX_PEAK_SUPER 1638.0 /* peak amplitude of supervisory signal */
#define BIT_RATE 1200 /* baud rate */
@@ -467,8 +467,7 @@ void sender_receive(sender_t *sender, int16_t *samples, int length)
spl = nmt->sender.rxbuf;
pos = nmt->sender.rxbuf_pos;
for (i = 0; i < count; i++) {
#warning hacking: remove after preemphasis implementation
spl[pos++] = down[i] / 2;
spl[pos++] = down[i];
if (pos == 160) {
call_tx_audio(nmt->sender.callref, spl, 160);
pos = 0;