diff --git a/firmware/scripts/wspr_coding b/firmware/scripts/wspr_coding
new file mode 100755
index 0000000..ed8466e
Binary files /dev/null and b/firmware/scripts/wspr_coding differ
diff --git a/firmware/scripts/wspr_coding.c b/firmware/scripts/wspr_coding.c
index 193d2dd..4317e95 100644
--- a/firmware/scripts/wspr_coding.c
+++ b/firmware/scripts/wspr_coding.c
@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <ctype.h>
 #include <stdint.h>
+#include <string.h>
 
 uint8_t wspr_call_char(char c) {
 	c = toupper(c);
@@ -37,7 +38,7 @@ uint8_t wspr_power(uint8_t power) {
 	return power;
 }
 
-uint64_t wspr_message(char *call, char* loc, uint8_t power) {
+uint64_t wspr_message(char *call, char *loc, uint8_t power) {
 	uint32_t m, n;
 
 	n = wspr_loc_char(call[0]);
@@ -54,13 +55,92 @@ uint64_t wspr_message(char *call, char* loc, uint8_t power) {
 	return n << 21 | m;
 }
 
+const uint32_t WSPR_FEC_TAPS1 = 0xF2D05351;
+const uint32_t WSPR_FEC_TAPS2 = 0xE4613C47;
 
+uint8_t wspr_parity32(uint32_t x) {
+	x ^= x >> 16;
+    x ^= x >> 8;
+    x ^= x >> 4;
+    x ^= x >> 2;
+    x ^= x >> 1;
+	return x & 1;
+}
+
+void wspr_fec(uint64_t msg, uint8_t *output) {
+	memset(output, 0, 162);
+
+	uint32_t reg = 0;
+	for(uint8_t i = 0;  i < 81; i++) {
+		uint8_t bit = 0;
+		if(i < 50) {
+			bit = (msg & (1 << (50 - i))) != 0;
+		}
+
+		reg = (reg << 1) | bit;
+
+		uint32_t tabs1 = reg & WSPR_FEC_TAPS1;
+		uint32_t tabs2 = reg & WSPR_FEC_TAPS2;
+
+		output[i * 2] = wspr_parity32(tabs1);
+		output[i * 2 + 1] = wspr_parity32(tabs2);
+	}
+}
+
+uint8_t wspr_reverse_bits(uint8_t bits) {
+	//https://gcc.gnu.org/onlinedocs/gcc-4.7.1/gcc/AVR-Built_002din-Functions.html
+	//return __builtin_avr_insert_bits (0x01234567, bits, 0);
+	return (bits & 0x80 ? 0x01 : 0) |
+       (bits & 0x40 ? 0x02 : 0) |
+       (bits & 0x20 ? 0x04 : 0) |
+       (bits & 0x10 ? 0x08 : 0) |
+       (bits & 0x08 ? 0x10 : 0) |
+       (bits & 0x04 ? 0x20 : 0) |
+       (bits & 0x02 ? 0x40 : 0) |
+       (bits & 0x01 ? 0x80 : 0);
+}
+
+
+void wspr_interleave(uint8_t *input, uint8_t *output) {
+	uint8_t p = 0;
+	uint8_t i = 0;
+	while(p < 162) {
+		uint8_t rev_i = wspr_reverse_bits(i);
+		if(rev_i < 162) {
+			output[rev_i] = input[p];
+			p++;
+		}
+		i++;
+	}
+}
+
+const uint8_t WSPR_SYNC[162] = {
+	1,1,0,0,0,0,0,0,1,0,0,0,1,1,1,0,0,0,1,0,0,1,0,1,1,1,1,0,0,0,0,0,0,0,1,0,0,1,0,1,0,0,
+	0,0,0,0,1,0,1,1,0,0,1,1,0,1,0,0,0,1,1,0,1,0,0,0,0,1,1,0,1,0,1,0,1,0,1,0,0,1,0,0,1,0,
+	1,1,0,0,0,1,1,0,1,0,1,0,0,0,1,0,0,0,0,0,1,0,0,1,0,0,1,1,1,0,1,1,0,0,1,1,0,1,0,0,0,1,
+	1,1,0,0,0,0,0,1,0,1,0,0,1,1,0,0,0,0,0,0,0,1,1,0,1,0,1,1,0,0,0,1,1,0.0,0
+};
+
+void wspr_add_sync(uint8_t *symbols) {
+	for(uint8_t i = 0; i < 161; i++) {
+		symbols[i] = WSPR_SYNC[i] + 2 * symbols[i];
+	}
+}
 
 int main(int argc, char const *argv[]) {
 
+	uint8_t test[161];
+	uint8_t test1[161];
+	uint64_t msg = wspr_message("DL1SSK", "JN39WE", 27);
 
+	wspr_fec(msg, test);
+	wspr_interleave(test, test1);
+	wspr_add_sync(test1);
 
-
+	for(uint8_t i = 0; i < 161; i++) {
+		printf("%d,", test1[i]);
+	}
+	printf("\n");
 
 	return 0;
 }