diff --git a/README.md b/README.md index e8202cc..418a7b6 100644 --- a/README.md +++ b/README.md @@ -12,7 +12,7 @@ dd if=/dev/urandom of=uncoded.dat bs=1 count=256 Encode file ```uncoded.dat``` to ```encoded.wav``` [WAV](https://en.wikipedia.org/wiki/WAV) audio file with 48000 Hz sample rate, 16 bits and only 1 (real) channel: ``` -./encode encoded.wav 48000 16 1 1500 5 uncoded.dat +./encode encoded.wav 48000 16 1 1500 ANONYMOUS 176 uncoded.dat ``` Start recording to ```recorded.wav``` audio file and stop after 5 seconds: @@ -41,19 +41,53 @@ diff -s uncoded.dat decoded.dat ### Supported Modes -All modes need a bandwidth of 2400 Hz and use a 1/2-rate forward error correction code +All modes need a bandwidth of 2400 Hz. -These use a differential modulation scheme: -* Mode 0: DBPSK, 2.6 seconds and 256 bytes -* Mode 1: DQPSK, 2.6 seconds and 512 bytes -* Mode 2: D8PSK, 3.4 seconds and 1024 bytes +These are the durations for each differential modulation scheme: -And these a coherent modulation scheme: -* Mode 3: BPSK, 2.6 seconds and 256 bytes -* Mode 4: QPSK, 2.6 seconds and 512 bytes -* Mode 5: QAM16, 1 second and 256 bytes -* Mode 6: QAM16, 2.6 seconds and 1024 bytes -* Mode 7: QAM64, 3.4 seconds and 2048 bytes +| Modulation | Short | Normal | +| ---------- | ----- | ------ | +| DBPSK | 1.5s | 2.6s | +| DQPSK | 1.0s | 1.5s | +| D8PSK | 1.9s | 3.4s | + +And these are the durations for each coherent modulation scheme: + +| Modulation | Short | Normal | +| ---------- | ----- | ------ | +| QAM16 | 1.0s | 1.5s | +| QAM64 | 1.9s | 3.4s | +| QAM256 | 1.5s | 2.6s | +| QAM1024 | 2.2s | 4.0s | +| QAM4096 | 1.9s | 3.4s | + +Currently all digital modes use a 1/2-rate forward error correction code. + +Therefore we have the following byte payloads for each modulation: + +| Modulation | Short | Normal | +| ---------- | ----- | ------ | +| DBPSK | 128B | 256B | +| DQPSK | 128B | 256B | +| D8PSK | 512B | 1024B | +| QAM16 | 256B | 512B | +| QAM64 | 1024B | 2048B | +| QAM256 | 1024B | 2048B | +| QAM1024 | 2048B | 4096B | +| QAM4096 | 2048B | 4096B | + +Which give us the following bitrates for each modulation: + +| Modulation | Short | Normal | +| ---------- | ------- | ------- | +| DBPSK | 681b/s | 789b/s | +| DQPSK | 1070b/s | 1362b/s | +| D8PSK | 2141b/s | 2398b/s | +| QAM16 | 2141b/s | 2725b/s | +| QAM64 | 4282b/s | 4795b/s | +| QAM256 | 5449b/s | 6310b/s | +| QAM1024 | 7493b/s | 8268b/s | +| QAM4096 | 8563b/s | 9591b/s | ### Simulating @@ -62,7 +96,7 @@ Prerequisite: [disorders](https://github.com/aicodix/disorders) Encode ```uncoded.dat``` to [analytic](https://en.wikipedia.org/wiki/Analytic_signal) audio signal, add [multipath](https://en.wikipedia.org/wiki/Multipath_propagation), [CFO, SFO](https://en.wikipedia.org/wiki/Carrier_frequency_offset), [AWGN](https://en.wikipedia.org/wiki/Additive_white_Gaussian_noise), decode and compare: ``` -./encode - 48000 16 2 1500 5 uncoded.dat | ../disorders/multipath - - ../disorders/multipath.txt 10 | ../disorders/cfo - - 234.567 | ../disorders/sfo - - 147 | ../disorders/awgn - - -20 | ./decode - - | diff -q -s uncoded.dat - +./encode - 48000 16 2 1500 ANONYMOUS 176 uncoded.dat | ../disorders/multipath - - ../disorders/multipath.txt 10 | ../disorders/cfo - - 234.567 | ../disorders/sfo - - 147 | ../disorders/awgn - - -20 | ./decode - - | diff -q -s uncoded.dat - ``` ### Reading