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Improved POCSAG receiver reliability

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This commit is contained in:
furrtek 2017-02-05 20:57:20 +00:00
parent 46482a110c
commit 98f89a84bb
11 changed files with 304 additions and 164 deletions
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45
firmware/baseband/proc_pocsag.cpp
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@ -29,13 +29,6 @@
#include <cstdint>
#include <cstddef>
#define POCSAG_AUDIO_RATE 24000
#define POCSAG_SYNC 0x7CD215D8
#define POCSAG_IDLE 0x7A89C197
#define POCSAG_PREAMBLE_LENGTH 576
#define POCSAG_BATCH_LENGTH (9 * 32)
void POCSAGProcessor::execute(const buffer_c8_t& buffer) {
// This is called at 1500Hz
@ -46,12 +39,11 @@ void POCSAGProcessor::execute(const buffer_c8_t& buffer) {
const auto decim_1_out = decim_1.execute(decim_0_out, dst_buffer);
const auto channel_out = channel_filter.execute(decim_1_out, dst_buffer);
auto audio = demod.execute(channel_out, audio_buffer);
//audio_output.write(audio);
// End up with 32 samples ?
for (uint32_t c = 0; c < 16; c++) {
const int32_t sample_int = audio.p[c] * 32768.0f;
//const int32_t audio_sample = audio.p[c] * 32768.0f;
const int32_t audio_sample = __SSAT(sample_int, 16);
slicer_sr <<= 1;
@ -84,23 +76,22 @@ void POCSAGProcessor::execute(const buffer_c8_t& buffer) {
break;
case PREAMBLE:
if (sync_timeout < POCSAG_PREAMBLE_LENGTH) {
if (sync_timeout < POCSAG_TIMEOUT) {
sync_timeout++;
if (rx_data == POCSAG_SYNC) {
packet.clear();
frame_counter = 0;
codeword_count = 0;
rx_bit = 0;
msg_timeout = 0;
last_rx_data = rx_data;
rx_state = SYNC;
} else if (rx_data == POCSAG_IDLE) {
push_packet(pocsag::PacketFlag::IDLE);
} /*else if (rx_data == POCSAG_IDLE) {
rx_state = WAITING;
}
}*/
} else {
rx_state = WAITING; // Timed out: abort
push_packet(pocsag::PacketFlag::TOO_LONG); // DEBUG
}
break;
@ -116,29 +107,18 @@ void POCSAGProcessor::execute(const buffer_c8_t& buffer) {
//pocsag_brute_repair(&s->l2.pocsag, &rx_data);
packet.set(frame_counter, rx_data);
packet.set(codeword_count, rx_data);
if ((rx_data == POCSAG_IDLE) && (!(last_rx_data & 0x80000000))) {
// SYNC then IDLE always means end of message ?
if (frame_counter)
push_packet(pocsag::PacketFlag::NORMAL);
else
push_packet(pocsag::PacketFlag::IDLE);
rx_state = WAITING;
if (codeword_count < 15) {
codeword_count++;
} else {
if (frame_counter < 15) {
frame_counter++;
} else {
// More than 17-1 codewords
push_packet(pocsag::PacketFlag::TOO_LONG);
rx_state = WAITING;
}
push_packet(pocsag::PacketFlag::NORMAL);
rx_state = WAITING;
}
last_rx_data = rx_data;
}
} else {
// Timed out (no end of message received)
packet.set(0, codeword_count); // DEBUG
push_packet(pocsag::PacketFlag::TIMED_OUT);
rx_state = WAITING;
}
@ -180,6 +160,7 @@ void POCSAGProcessor::configure(const POCSAGConfigureMessage& message) {
decim_1.configure(taps_11k0_decim_1.taps, 131072);
channel_filter.configure(taps_11k0_channel.taps, 2);
demod.configure(demod_input_fs, 4500);
//audio_output.configure(false);
bitrate = message.bitrate;
sphase_delta = 0x10000u * bitrate / POCSAG_AUDIO_RATE;