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AIS decoding and really bad UI.

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The decoder needs a serious refactoring/decoupling.
The UI just dumps bits of the received packets into a console window, whcih scrolls too quickly in an AIS-dense area with a good antenna.
This commit is contained in:
Jared Boone 2015-11-06 13:53:04 -08:00
parent a366b3ac4f
commit 9e694ce836
5 changed files with 388 additions and 148 deletions
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1
firmware/application/Makefile
View File

@ -167,6 +167,7 @@ CPPSRC = main.cpp \
ui_spectrum.cpp \
receiver_model.cpp \
spectrum_color_lut.cpp \
ais_baseband.cpp \
../common/utility.cpp \
../common/chibios_cpp.cpp \
../common/debug.cpp \

12
firmware/application/ui_receiver.cpp
View File

@ -27,6 +27,8 @@
#include "portapack.hpp"
using namespace portapack;
#include "ais_baseband.hpp"
namespace ui {
/* BasebandBandwidthField ************************************************/
@ -496,8 +498,8 @@ ReceiverView::~ReceiverView() {
void ReceiverView::on_show() {
context().message_map.register_handler(Message::ID::FSKPacket,
[this](Message* const p) {
auto message = static_cast<FSKPacketMessage*>(p);
(void)message;
const auto message = static_cast<const FSKPacketMessage*>(p);
this->on_packet_ais(*message);
}
);
}
@ -506,7 +508,13 @@ void ReceiverView::on_hide() {
context().message_map.unregister_handler(Message::ID::FSKPacket);
}
void ReceiverView::on_packet_ais(const FSKPacketMessage& message) {
const auto result = baseband::ais::packet_decode(message.packet.payload, message.packet.bits_received);
auto console = reinterpret_cast<Console*>(widget_content.get());
if( result.first == "OK" ) {
console->writeln(result.second);
}
}
void ReceiverView::focus() {

3
firmware/application/ui_receiver.hpp
View File

@ -415,6 +415,7 @@ private:
{ " AM ", 0 },
{ "NFM ", 1 },
{ "WFM ", 2 },
{ "AIS ", 3 },
{ "SPEC", 4 },
}
};
@ -470,6 +471,8 @@ private:
void on_headphone_volume_changed(int32_t v);
// void on_baseband_oversampling_changed(int32_t v);
void on_edit_frequency();
void on_packet_ais(const FSKPacketMessage& message);
};
} /* namespace ui */

371
firmware/common/ais_baseband.cpp Normal file
View File

@ -0,0 +1,371 @@
/*
* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
*
* This file is part of PortaPack.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#include "ais_baseband.hpp"
#include <cstdint>
#include <cstddef>
#include <cstdlib>
#include <string>
#include "crc.hpp"
// TODO: Move string formatting elsewhere!!!
#include "ui_widget.hpp"
namespace baseband {
template<typename T, typename BitRemap>
class FieldReader {
public:
constexpr FieldReader(
const T& data
) : data { data }
{
}
uint32_t read(const size_t start_bit, const size_t length) const {
uint32_t value = 0;
for(size_t i=start_bit; i<(start_bit + length); i++) {
value = (value << 1) | data[bit_remap(i)];
}
return value;
}
private:
const T& data;
const BitRemap bit_remap { };
};
namespace ais {
struct BitRemap {
size_t operator()(const size_t bit_index) const {
return bit_index ^ 7;
}
};
struct CRCBitRemap {
size_t operator()(const size_t bit_index) const {
return bit_index;
}
};
using FieldReader = baseband::FieldReader<std::bitset<1024>, BitRemap>;
using CRCFieldReader = baseband::FieldReader<std::bitset<1024>, CRCBitRemap>;
struct PacketLengthRange {
constexpr PacketLengthRange(
) : min_bytes { 0 },
max_bytes { 0 }
{
}
constexpr PacketLengthRange(
const uint16_t min_bits,
const uint16_t max_bits
) : min_bytes { static_cast<uint8_t>(min_bits / 8U) },
max_bytes { static_cast<uint8_t>(max_bits / 8U) }
{
// static_assert((min_bits & 7) == 0, "minimum bits not a multiple of 8");
// static_assert((max_bits & 7) == 0, "minimum bits not a multiple of 8");
}
bool contains(const size_t bit_count) const {
return !is_above(bit_count) && !is_below(bit_count);
}
bool is_above(const size_t bit_count) const {
return (min() > bit_count);
}
bool is_below(const size_t bit_count) const {
return (max() < bit_count);
}
size_t min() const {
return min_bytes * 8;
}
size_t max() const {
return max_bytes * 8;
}
private:
const uint8_t min_bytes;
const uint8_t max_bytes;
};
static constexpr std::array<PacketLengthRange, 64> packet_length_range { {
{ 0, 0 }, // 0
{ 168, 168 }, // 1
{ 168, 168 }, // 2
{ 168, 168 }, // 3
{ 168, 168 }, // 4
{ 424, 424 }, // 5
{ 0, 0 }, // 6
{ 0, 0 }, // 7
{ 0, 1008 }, // 8
{ 0, 0 }, // 9
{ 0, 0 }, // 10
{ 0, 0 }, // 11
{ 0, 0 }, // 12
{ 0, 0 }, // 13
{ 0, 0 }, // 14
{ 0, 0 }, // 15
{ 0, 0 }, // 16
{ 0, 0 }, // 17
{ 168, 168 }, // 18
{ 0, 0 }, // 19
{ 72, 160 }, // 20
{ 272, 360 }, // 21
{ 168, 168 }, // 22
{ 160, 160 }, // 23
{ 160, 168 }, // 24
{ 0, 168 }, // 25
{ 0, 0 }, // 26
{ 0, 0 }, // 27
{ 0, 0 }, // 28
{ 0, 0 }, // 29
{ 0, 0 }, // 30
{ 0, 0 }, // 31
} };
struct PacketLengthValidator {
bool operator()(const uint_fast8_t message_id, const size_t length) {
return packet_length_range[message_id].contains(length);
}
};
struct PacketTooLong {
bool operator()(const uint_fast8_t message_id, const size_t length) {
return packet_length_range[message_id].is_below(length);
}
};
struct CRCCheck {
bool operator()(const std::bitset<1024>& payload, const size_t data_length) {
CRCFieldReader field_crc { payload };
CRC<uint16_t> ais_fcs { 0x1021 };
uint16_t crc_calculated = 0xffff;
for(size_t i=0; i<data_length + 16; i+=8) {
if( i == data_length ) {
crc_calculated ^= 0xffff;
}
const uint8_t byte = field_crc.read(i, 8);
crc_calculated = ais_fcs.calculate_byte(crc_calculated, byte);
}
return crc_calculated == 0x0000;
}
};
static int32_t ais_latitude_normalized(
const FieldReader& field,
const size_t start_bit
) {
// Shifting and dividing is to sign-extend the source field.
// TODO: There's probably a more elegant way to do it.
return static_cast<int32_t>(field.read(start_bit, 27) << 5) / 32;
}
static int32_t ais_longitude_normalized(
const FieldReader& field,
const size_t start_bit
) {
// Shifting and dividing is to sign-extend the source field.
// TODO: There's probably a more elegant way to do it.
return static_cast<int32_t>(field.read(start_bit, 28) << 4) / 16;
}
static std::string ais_format_latlon_normalized(const int32_t normalized) {
const int32_t t = (normalized * 5) / 3;
const int32_t degrees = t / (100 * 10000);
const int32_t fraction = std::abs(t) % (100 * 10000);
return ui::to_string_dec_int(degrees) + "." + ui::to_string_dec_int(fraction, 6, '0');
}
static std::string ais_format_latitude(
const FieldReader& field,
const size_t start_bit
) {
const auto value = static_cast<int32_t>(field.read(start_bit, 27) << 5) / 32;
return ais_format_latlon_normalized(value);
}
static std::string ais_format_longitude(
const FieldReader& field,
const size_t start_bit
) {
const auto value = static_cast<int32_t>(field.read(start_bit, 28) << 4) / 16;
return ais_format_latlon_normalized(value);
}
struct ais_datetime {
uint16_t year;
uint8_t month;
uint8_t day;
uint8_t hour;
uint8_t minute;
uint8_t second;
};
static ais_datetime ais_get_datetime(
const FieldReader& field,
const size_t start_bit
) {
return {
static_cast<uint16_t>(field.read(start_bit + 0, 14)),
static_cast<uint8_t >(field.read(start_bit + 14, 4)),
static_cast<uint8_t >(field.read(start_bit + 18, 5)),
static_cast<uint8_t >(field.read(start_bit + 23, 5)),
static_cast<uint8_t >(field.read(start_bit + 28, 6)),
static_cast<uint8_t >(field.read(start_bit + 34, 6)),
};
}
static std::string ais_format_datetime(
const FieldReader& field,
const size_t start_bit
) {
const auto datetime = ais_get_datetime(field, start_bit);
return ui::to_string_dec_uint(datetime.year, 4) + "/" +
ui::to_string_dec_uint(datetime.month, 2, '0') + "/" +
ui::to_string_dec_uint(datetime.day, 2, '0') + " " +
ui::to_string_dec_uint(datetime.hour, 2, '0') + ":" +
ui::to_string_dec_uint(datetime.minute, 2, '0') + ":" +
ui::to_string_dec_uint(datetime.second, 2, '0');
}
static char ais_char_to_ascii(const uint8_t c) {
return (c ^ 32) + 32;
}
static std::string ais_read_text(
const FieldReader& field,
const size_t start_bit,
const size_t character_count
) {
std::string result;
const size_t character_length = 6;
const size_t end_bit = start_bit + character_count * character_length;
for(size_t i=start_bit; i<end_bit; i+=character_length) {
result += ais_char_to_ascii(field.read(i, character_length));
}
return result;
}
static std::string ais_format_navigational_status(const unsigned int value) {
switch(value) {
case 0: return "under way w/engine";
case 1: return "at anchor";
case 2: return "not under command";
case 3: return "restricted maneuv";
case 4: return "constrained draught";
case 5: return "moored";
case 6: return "aground";
case 7: return "fishing";
case 8: return "sailing";
case 9: case 10: case 13: return "reserved";
case 11: return "towing astern";
case 12: return "towing ahead/along";
case 14: return "SART/MOB/EPIRB";
case 15: return "undefined";
default: return "unexpected";
}
}
decoded_packet packet_decode(const std::bitset<1024>& data, const size_t data_length) {
if( data_length < 38 ) {
return { "short " + ui::to_string_dec_uint(data_length, 3), "" };
}
const size_t extra_bits = data_length & 7;
if( extra_bits != 0 ) {
return { "extra bits " + ui::to_string_dec_uint(data_length, 3), "" };
}
FieldReader field { data };
const auto message_id = field.read(0, 6);
const size_t payload_length = data_length - 16;
PacketLengthValidator packet_length_valid;
if( !packet_length_valid(message_id, payload_length) ) {
return { "bad length " + ui::to_string_dec_uint(payload_length, 3), "" };
}
CRCCheck crc_ok;
if( !crc_ok(data, payload_length) ) {
return { "crc", "" };
}
const auto source_id = field.read(8, 30);
std::string result { ui::to_string_dec_uint(message_id, 2) + " " + ui::to_string_dec_uint(source_id, 10) };
switch(message_id) {
case 1:
case 2:
case 3:
{
const auto navigational_status = field.read(38, 4);
result += " " + ais_format_navigational_status(navigational_status);
result += " " + ais_format_latlon_normalized(ais_latitude_normalized(field, 89));
result += " " + ais_format_latlon_normalized(ais_longitude_normalized(field, 61));
}
break;
case 4:
{
result += " " + ais_format_datetime(field, 38);
result += " " + ais_format_latlon_normalized(ais_latitude_normalized(field, 107));
result += " " + ais_format_latlon_normalized(ais_longitude_normalized(field, 79));
}
break;
case 5:
{
const auto call_sign = ais_read_text(field, 70, 7);
const auto name = ais_read_text(field, 112, 20);
const auto destination = ais_read_text(field, 302, 20);
result += " \"" + call_sign + "\" \"" + name + "\" \"" + destination + "\"";
}
break;
case 21:
{
const auto name = ais_read_text(field, 43, 20);
result += " \"" + name + "\" " + ais_format_latitude(field, 192) + " " + ais_format_longitude(field, 164);
}
break;
default:
break;
}
return { "OK", result };
}
} /* namespace ais */
} /* namespace baseband */

149
firmware/common/ais_baseband.hpp
View File

@ -22,38 +22,14 @@
#ifndef __AIS_BASEBAND_H__
#define __AIS_BASEBAND_H__
#include "crc.hpp"
#include <cstdint>
#include <cstddef>
#include <complex>
#include <array>
#include <bitset>
#include <utility>
namespace baseband {
template<typename T, typename BitRemap>
class FieldReader {
public:
constexpr FieldReader(
const T& data
) : data { data }
{
}
uint32_t read(const size_t start_bit, const size_t length) const {
uint32_t value = 0;
for(size_t i=start_bit; i<(start_bit + length); i++) {
value = (value << 1) | data[bit_remap(i)];
}
return value;
}
private:
const T& data;
const BitRemap bit_remap { };
};
namespace ais {
// RRC length should be about 4 x the symbol length to do a good job of
@ -209,128 +185,9 @@ constexpr std::array<std::complex<float>, 128> rrc_taps_128_decim_1_p { {
{ -1.1001696231e-04f, 4.5570517881e-05f }, { -2.5877077742e-04f, 5.1472707944e-05f },
} };
struct BitRemap {
size_t operator()(const size_t bit_index) const {
return bit_index ^ 7;
}
};
using decoded_packet = std::pair<std::string, std::string>;
struct CRCBitRemap {
size_t operator()(const size_t bit_index) const {
return bit_index;
}
};
using FieldReader = baseband::FieldReader<std::bitset<1024>, BitRemap>;
using CRCFieldReader = baseband::FieldReader<std::bitset<1024>, CRCBitRemap>;
struct PacketLengthRange {
constexpr PacketLengthRange(
) : min_bytes { 0 },
max_bytes { 0 }
{
}
constexpr PacketLengthRange(
const uint16_t min_bits,
const uint16_t max_bits
) : min_bytes { static_cast<uint8_t>(min_bits / 8U) },
max_bytes { static_cast<uint8_t>(max_bits / 8U) }
{
// static_assert((min_bits & 7) == 0, "minimum bits not a multiple of 8");
// static_assert((max_bits & 7) == 0, "minimum bits not a multiple of 8");
}
bool contains(const size_t bit_count) const {
return !is_above(bit_count) && !is_below(bit_count);
}
bool is_above(const size_t bit_count) const {
return (min() > bit_count);
}
bool is_below(const size_t bit_count) const {
return (max() < bit_count);
}
size_t min() const {
return min_bytes * 8;
}
size_t max() const {
return max_bytes * 8;
}
private:
const uint8_t min_bytes;
const uint8_t max_bytes;
};
constexpr std::array<PacketLengthRange, 64> packet_length_range { {
{ 0, 0 }, // 0
{ 168, 168 }, // 1
{ 168, 168 }, // 2
{ 168, 168 }, // 3
{ 168, 168 }, // 4
{ 424, 424 }, // 5
{ 0, 0 }, // 6
{ 0, 0 }, // 7
{ 0, 1008 }, // 8
{ 0, 0 }, // 9
{ 0, 0 }, // 10
{ 0, 0 }, // 11
{ 0, 0 }, // 12
{ 0, 0 }, // 13
{ 0, 0 }, // 14
{ 0, 0 }, // 15
{ 0, 0 }, // 16
{ 0, 0 }, // 17
{ 168, 168 }, // 18
{ 0, 0 }, // 19
{ 72, 160 }, // 20
{ 272, 360 }, // 21
{ 168, 168 }, // 22
{ 160, 160 }, // 23
{ 160, 168 }, // 24
{ 0, 168 }, // 25
{ 0, 0 }, // 26
{ 0, 0 }, // 27
{ 0, 0 }, // 28
{ 0, 0 }, // 29
{ 0, 0 }, // 30
{ 0, 0 }, // 31
} };
struct PacketLengthValidator {
bool operator()(const uint_fast8_t message_id, const size_t length) {
return packet_length_range[message_id].contains(length);
}
};
struct PacketTooLong {
bool operator()(const uint_fast8_t message_id, const size_t length) {
return packet_length_range[message_id].is_below(length);
}
};
struct CRCCheck {
bool operator()(const std::bitset<1024>& payload, const size_t data_length) {
CRCFieldReader field_crc { payload };
CRC<uint16_t> ais_fcs { 0x1021 };
uint16_t crc_calculated = 0xffff;
for(size_t i=0; i<data_length + 16; i+=8) {
if( i == data_length ) {
crc_calculated ^= 0xffff;
}
const uint8_t byte = field_crc.read(i, 8);
crc_calculated = ais_fcs.calculate_byte(crc_calculated, byte);
}
return crc_calculated == 0x0000;
}
};
decoded_packet packet_decode(const std::bitset<1024>& data, const size_t data_length);
} /* namespace ais */
} /* namespace baseband */