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track.c
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// Part of readsb, a Mode-S/ADSB/TIS message decoder.
//
// track.c: aircraft state tracking
//
// Copyright (c) 2019 Michael Wolf <[email protected]>
//
// This code is based on a detached fork of dump1090-fa.
//
// Copyright (c) 2014-2016 Oliver Jowett <[email protected]>
//
// This file 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 3 of the License, or
// any later version.
//
// This file 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. If not, see <http://www.gnu.org/licenses/>.
//
// This file incorporates work covered by the following copyright and
// license:
//
// Copyright (C) 2012 by Salvatore Sanfilippo <[email protected]>
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "readsb.h"
uint32_t modeAC_count[4096];
uint32_t modeAC_lastcount[4096];
uint32_t modeAC_match[4096];
uint32_t modeAC_age[4096];
static void showPositionDebug(struct aircraft *a, struct modesMessage *mm, int64_t now, double bad_lat, double bad_lon);
static void position_bad(struct modesMessage *mm, struct aircraft *a);
static void calc_wind(struct aircraft *a, int64_t now);
static void calc_temp(struct aircraft *a, int64_t now);
static inline int declination(struct aircraft *a, double *dec, int64_t now);
static const char *source_string(datasource_t source);
static void incrementReliable(struct aircraft *a, struct modesMessage *mm, int64_t now, int odd);
static uint16_t simpleHash(uint64_t receiverId) {
uint16_t simpleHash = receiverId;
simpleHash ^= (uint16_t) (receiverId >> 16);
simpleHash ^= (uint16_t) (receiverId >> 32);
simpleHash ^= (uint16_t) (receiverId >> 48);
if (simpleHash == 0)
return 1;
return simpleHash;
}
static float knots_to_meterpersecond = (1852.0 / 3600.0);
static void calculateMessageRate(struct aircraft *a, int64_t now) {
float sum = 0.0f;
float mult = REMOVE_STALE_INTERVAL / 1000.0f;
float multSum = 0.0f;
for (int k = 0; k < MESSAGE_RATE_CALC_POINTS; k++) {
sum += a->messageRateAcc[k] * mult;
multSum += mult;
mult *= 0.7f;
}
a->messageRate = sum / multSum * Modes.messageRateMult;
a->nextMessageRateCalc = now + REMOVE_STALE_INTERVAL;
memmove(&a->messageRateAcc[1], &a->messageRateAcc[0], sizeof(uint16_t) * (MESSAGE_RATE_CALC_POINTS - 1));
a->messageRateAcc[0] = 0;
}
// Should we accept some new data from the given source?
// If so, update the validity and return 1
static int32_t currentReduceInterval(int64_t now) {
return Modes.net_output_beast_reduce_interval * (1 + (Modes.doubleBeastReduceIntervalUntil > now));
}
static inline int will_accept_data(data_validity *d, datasource_t source, struct modesMessage *mm, struct aircraft *a) {
int64_t now = mm->sysTimestamp;
if (source == SOURCE_INVALID) {
return 0;
}
if (now < d->updated) {
return 0;
}
if (source < d->source && now < d->updated + TRACK_STALE) {
return 0;
}
// this is a position and will be wholly reverted if it's not accepted
//int is_pos = (mm->sbs_pos_valid || mm->cpr_valid || d == &a->pos_reliable_valid || d == &a->position_valid || d == &a->cpr_odd_valid || d == &a->cpr_even_valid || d == &a->mlat_pos_valid);
int is_pos = (mm->sbs_pos_valid || mm->cpr_valid);
// if we have a jaero position, don't allow non-position data to have a lesser source
if (!is_pos && a->pos_reliable_valid.source == SOURCE_JAERO && source < SOURCE_JAERO) {
return 0;
}
// prevent JAERO from disrupting other data sources too quickly
if (source == SOURCE_JAERO && a->pos_reliable_valid.last_source != SOURCE_JAERO && now < d->updated + 7 * MINUTES) {
return 0;
}
// if we have recent data and a recent position, only accept data from the last couple receivers that contributed a position
// this hopefully reduces data jitter introduced by differing receiver latencies
// it's important to excluded data coming in alongside positions, that extra data if accepted is discarded via the scratch mechanism
if (Modes.netReceiverId && !is_pos && a->pos_reliable_valid.source >= SOURCE_TISB && now - d->updated < 5 * SECONDS && now - a->seenPosReliable < 2200 * MS) {
uint16_t hash = simpleHash(mm->receiverId);
uint32_t found = 0;
for (int i = 0; i < RECEIVERIDBUFFER; i++) {
found += (a->receiverIds[i] == hash);
}
if (!found) {
return 0;
}
}
if (0 && is_pos && a->addr == Modes.cpr_focus) {
//fprintf(stderr, "%d %p %p\n", mm->duplicate, d, &a->pos_reliable_valid);
fprintf(stderr, "%d %s", mm->duplicate, source_string(mm->source));
}
return 1;
}
static int accept_data(data_validity *d, datasource_t source, struct modesMessage *mm, struct aircraft *a, int reduce_often) {
if (!will_accept_data(d, source, mm, a)) {
return 0;
}
int64_t now = mm->sysTimestamp;
d->source = source;
if (unlikely(source == SOURCE_PRIO)) {
d->source = SOURCE_ADSB;
}
d->last_source = d->source;
d->updated = now;
d->stale = 0;
if (now > d->next_reduce_forward || mm->reduce_forward) {
int32_t reduceInterval = currentReduceInterval(now);
if (reduce_often == REDUCE_OFTEN) {
reduceInterval = reduceInterval * 3 / 4;
} else if (reduce_often == REDUCE_RARE) {
reduceInterval = reduceInterval * 4;
}
if (mm->cpr_valid && reduceInterval > 7000) {
// make sure global CPR stays possible even at high interval:
reduceInterval = 7000;
}
d->next_reduce_forward = now + reduceInterval;
mm->reduce_forward = 1;
}
return 1;
}
// Given two datasources, produce a third datasource for data combined from them.
static void combine_validity(data_validity *to, const data_validity *from1, const data_validity *from2, int64_t now) {
if (from1->source == SOURCE_INVALID) {
*to = *from2;
return;
}
if (from2->source == SOURCE_INVALID) {
*to = *from1;
return;
}
to->source = (from1->source < from2->source) ? from1->source : from2->source; // the worse of the two input sources
to->last_source = to->source;
to->updated = (from1->updated > from2->updated) ? from1->updated : from2->updated; // the *later* of the two update times
to->stale = (now > to->updated + TRACK_STALE);
}
static int compare_validity(const data_validity *lhs, const data_validity *rhs) {
if (!lhs->stale && lhs->source > rhs->source)
return 1;
else if (!rhs->stale && lhs->source < rhs->source)
return -1;
else if (lhs->updated >= rhs->updated)
return 1;
else if (lhs->updated < rhs->updated)
return -1;
else
return 0;
}
static void update_range_histogram(struct aircraft *a, int64_t now) {
double lat = a->lat;
double lon = a->lon;
double range = a->receiver_distance;
int rangeDirDirection = ((int) nearbyint(a->receiver_direction)) % RANGEDIRS_BUCKETS;
int rangeDirIval = (now * (RANGEDIRS_IVALS - 1) / Modes.range_outline_duration) % RANGEDIRS_IVALS;
if (rangeDirIval != Modes.lastRangeDirHour) {
//log_with_timestamp("rangeDirIval: %d", rangeDirIval);
// when the current interval changes, reset the data for it
memset(Modes.rangeDirs[rangeDirIval], 0, sizeof(Modes.rangeDirs[rangeDirIval]));
Modes.lastRangeDirHour = rangeDirIval;
}
struct distCoords *current = &(Modes.rangeDirs[rangeDirIval][rangeDirDirection]);
// if the position isn't proper reliable, only allow it if the range in that direction is increased by less than 25 nmi compared to the maximum of the last 24h
if (range > current->distance && (a->pos_reliable_odd < 2 || a->pos_reliable_even < 2)) {
float directionMax = 0;
for (int i = 0; i < RANGEDIRS_IVALS; i++) {
if (Modes.rangeDirs[i][rangeDirDirection].distance > directionMax)
directionMax = Modes.rangeDirs[i][rangeDirDirection].distance;
}
directionMax += 50.0f * 1852.0f; // allow 50 nmi more than recorded for that direction in the last 24h
if (range > directionMax && !Modes.debug_bogus && Modes.json_reliable > 0) {
return;
}
//fprintf(stderr, "actual %.1f max %.1f\n", range / 1852.0f, (directionMax / 1852.0f));
}
if (range > current->distance) {
current->distance = range;
current->lat = lat;
current->lon = lon;
if (trackDataValid(&a->baro_alt_valid) || !trackDataValid(&a->geom_alt_valid)) {
current->alt = a->baro_alt;
} else {
current->alt = a->geom_alt;
}
}
if (range > Modes.stats_current.distance_max)
Modes.stats_current.distance_max = range;
if (range < Modes.stats_current.distance_min)
Modes.stats_current.distance_min = range;
int bucket = round(range / Modes.maxRange * RANGE_BUCKET_COUNT);
if (bucket < 0)
bucket = 0;
else if (bucket >= RANGE_BUCKET_COUNT)
bucket = RANGE_BUCKET_COUNT - 1;
++Modes.stats_current.range_histogram[bucket];
}
static int cpr_duplicate_check(int64_t now, struct aircraft *a, struct modesMessage *mm) {
struct cpr_cache *cpr;
uint32_t inCache = 0;
uint32_t cpr_lat = mm->cpr_lat;
uint32_t cpr_lon = mm->cpr_lon;
uint64_t receiverId = mm->receiverId;
for (int i = 0; i < CPR_CACHE; i++) {
cpr = &a->cpr_cache[i];
if (
(
now - cpr->ts < 2 * SECONDS
&& cpr->cpr_lat == cpr_lat
&& cpr->cpr_lon == cpr_lon
&& cpr->receiverId != receiverId
)
) {
inCache += 1;
}
}
if (inCache > 0) {
mm->duplicate = 1;
return 1;
} else {
// CPR not yet known to cpr cache
a->cpr_cache_index = (a->cpr_cache_index + 1) % CPR_CACHE;
cpr = &a->cpr_cache[a->cpr_cache_index];
cpr->ts = now;
cpr->cpr_lat = cpr_lat;
cpr->cpr_lon = cpr_lon;
cpr->receiverId = receiverId;
return 0;
}
}
static int duplicate_check(int64_t now, struct aircraft *a, double new_lat, double new_lon, struct modesMessage *mm) {
if (mm->duplicate_checked || mm->duplicate) {
// already checked
return mm->duplicate;
}
mm->duplicate_checked = 1;
// if the last position is older than 2 seconds we don't consider it a duplicate
if (now > a->seen_pos + 2 * SECONDS) {
return 0;
}
// duplicate
if (a->lat == new_lat && a->lon == new_lon) {
mm->duplicate = 1;
return 1;
}
// if the previous position is older than 2 seconds we don't consider it a duplicate
if (now > a->prev_pos_time + 2 * SECONDS) {
return 0;
}
// duplicate (this happens either with some transponder or delayed data arrival due to odd / even CPR, not certain)
if (a->prev_lat == new_lat && a->prev_lon == new_lon) {
mm->duplicate = 1;
return 1;
}
return 0;
}
static int uat2esnt_duplicate(int64_t now, struct aircraft *a, struct modesMessage *mm) {
return (
mm->cpr_valid && mm->cpr_odd && mm->msgtype == 18
&& (mm->timestamp == MAGIC_UAT_TIMESTAMP || mm->timestamp == 0)
&& now - a->seenPosReliable < 2500
);
}
static int inDiscCache(int64_t now, struct aircraft *a, struct modesMessage *mm) {
struct cpr_cache *disc;
uint32_t inCache = 0;
uint32_t cpr_lat = mm->cpr_lat;
uint32_t cpr_lon = mm->cpr_lon;
uint64_t receiverId = mm->receiverId;
for (int i = 0; i < DISCARD_CACHE; i++) {
disc = &a->disc_cache[i];
// don't decrement pos_reliable if we already got the same bad position within the last second
// rate limit reliable decrement per receiver
if (
(
now - disc->ts < 4 * SECONDS
&& disc->cpr_lat == cpr_lat
&& disc->cpr_lon == cpr_lon
)
||
(
now - disc->ts < 300
&& disc->receiverId == receiverId
)
) {
inCache += 1;
}
}
if (inCache > 0) {
return 1;
} else {
return 0;
}
}
// return true if it's OK for the aircraft to have travelled from its last known position
// to a new position at (lat,lon,surface) at a time of now.
static int speed_check(struct aircraft *a, datasource_t source, double lat, double lon, struct modesMessage *mm, cpr_local_t cpr_local) {
int64_t now = mm->sysTimestamp;
int64_t elapsed = trackDataAge(now, &a->position_valid);
int receiverRangeExceeded = 0;
if (0 && mm->sbs_in && a->addr == Modes.cpr_focus) {
fprintf(stderr, ".");
}
if (duplicate_check(now, a, lat, lon, mm)) {
// don't use duplicate positions
mm->pos_ignore = 1;
// but count it as a received position towards receiver heuristics
if (!Modes.userLocationValid) {
receiverPositionReceived(a, mm, lat, lon, now);
}
if (elapsed > 200 && a->receiverId == mm->receiverId && (Modes.debug_cpr || Modes.debug_speed_check || a->addr == Modes.cpr_focus)) {
// let speed_check continue for displaying this duplicate (at least for non-aggregated receivers)
} else {
// omit rest of speed check to save on cycles
return 1;
}
}
if (0 && (a->prev_lat == lat && a->prev_lon == lon) && (Modes.debug_cpr || Modes.debug_speed_check || a->addr == Modes.cpr_focus)) {
fprintf(stderr, "%06x now - seen_pos %6.3f now - prev_pos_time %6.3f\n",
a->addr,
(now - a->seen_pos) / 1000.0,
(now - a->prev_pos_time) / 1000.0
);
}
if (mm->cpr_valid && inDiscCache(now, a, mm)) {
mm->in_disc_cache = 1;
}
float distance = -1;
float range = -1;
float speed = -1;
float transmitted_speed = -1;
float calc_track = -1;
int inrange;
int override = 0;
double oldLat = a->lat;
double oldLon = a->lon;
int surface = trackDataValid(&a->airground_valid)
&& a->airground == AG_GROUND
&& a->pos_surface
&& (!mm->cpr_valid || mm->cpr_type == CPR_SURFACE);
// json_reliable == -1 disables the speed check
if (Modes.json_reliable == -1 || mm->source == SOURCE_PRIO) {
override = 1;
} else if (bogus_lat_lon(lat, lon) ||
(mm->cpr_valid && mm->cpr_lat == 0 && mm->cpr_lon == 0)
|| (
mm->cpr_valid && (mm->cpr_lat == 0 || mm->cpr_lon == 0)
&& (a->position_valid.source < SOURCE_TISB || !posReliable(a))
)
) {
mm->pos_ignore = 1; // don't decrement pos_reliable
} else if (a->pos_reliable_odd < 0.2 || a->pos_reliable_even < 0.2) {
override = 1;
} else if (now - a->position_valid.updated > POS_RELIABLE_TIMEOUT) {
override = 1; // no reference or older than 60 minutes, assume OK
} else if (source > a->position_valid.source && source > a->position_valid.last_source && source > a->pos_reliable_valid.source) {
override = 1; // data is better quality, OVERRIDE
} else if (source > a->position_valid.source && a->position_valid.source == SOURCE_INDIRECT) {
override = 1; // data is better quality, OVERRIDE
} else if (source <= SOURCE_MLAT && elapsed > 45 * SECONDS) {
override = 1;
} else if (a->addr == 0xa19b53) {
// Virgin SS2
override = 1;
}
if (mm->in_disc_cache) {
override = 0; // don't override if in discard cache
}
if (trackDataValid(&a->gs_valid)) {
// use the larger of the current and earlier speed
speed = (a->gs_last_pos > a->gs) ? a->gs_last_pos : a->gs;
// add 3 knots for every second we haven't known the speed and the position
speed = speed + (3 * trackDataAge(now, &a->gs_valid)/1000.0f) + (3 * trackDataAge(now, &a->position_valid)/1000.0f);
} else if (trackDataValid(&a->tas_valid)) {
speed = a->tas * 4 / 3;
} else if (trackDataValid(&a->ias_valid)) {
speed = a->ias * 2;
}
transmitted_speed = speed;
// find actual distance
distance = greatcircle(oldLat, oldLon, lat, lon, 0);
mm->distance_traveled = distance;
float track_diff = -1;
float track_bonus = 0;
int64_t track_max_age = 5 * SECONDS;
int64_t track_age = -1;
float track = -1;
if (trackDataAge(now, &a->track_valid) < track_max_age) {
track = a->track;
track_age = trackDataAge(now, &a->track_valid);
} else if (trackDataAge(now, &a->true_heading_valid) < track_max_age) {
track = a->true_heading;
track_age = trackDataAge(now, &a->true_heading_valid);
}
if (distance > 2.5f) {
calc_track = bearing(oldLat, oldLon, lat, lon);
mm->calculated_track = calc_track;
if (source != SOURCE_MLAT
&& track > -1
&& trackDataAge(now, &a->position_valid) < 7 * SECONDS
) {
track_diff = fabs(norm_diff(track - calc_track, 180));
}
}
if (track_diff > 70.0f) {
mm->trackUnreliable = +1;
} else if (track_diff > -1) {
mm->trackUnreliable = -1;
}
if (!posReliable(a)) {
// don't use track_diff for further calculations unless position is already reliable
track_diff = -1;
}
if (speed < 0 || a->speedUnreliable > 8) {
speed = surface ? 120 : 900; // guess
}
if (speed > 1 && track_diff > -1 && a->trackUnreliable < 8) {
track_bonus = speed * (90.0f - track_diff) / 90.0f;
track_bonus *= (surface ? 0.9f : 1.0f) * (1.0f - track_age / track_max_age);
if (a->gs < 10) {
// don't allow negative "bonus" below 10 knots speed
track_bonus = fmaxf(0.0f, track_bonus);
speed += 2;
}
speed += track_bonus;
if (track_diff > 160) {
mm->pos_old = 1; // don't decrement pos_reliable
}
// allow relatively big forward jumps
if (speed > 40 && track_diff < 10) {
range += 2e3;
}
} else {
// Work out a reasonable speed to use:
// current speed + 1/3
speed = speed * 1.3f;
}
if (surface) {
range += 10;
} else {
range += 30;
}
// same TCP packet (2 ms), two positions from same receiver id, allow plenty of extra range
if (elapsed < 2 && a->receiverId == mm->receiverId && source > SOURCE_MLAT) {
range += 500; // 500 m extra in this case
}
// cap speed at 2000 knots ..
speed = fmin(speed, 2000);
if (source == SOURCE_MLAT) {
speed *= 1.4;
speed += 50;
range += 250;
}
if (distance > 2.5f && (track_diff < 70 || track_diff == -1)) {
if (distance <= range + (((float) elapsed + 50.0f) * (1.0f / 1000.0f)) * (transmitted_speed * knots_to_meterpersecond)) {
mm->speedUnreliable = -1;
} else if (distance > range + (((float) elapsed + 400.0f) * (1.0f / 1000.0f)) * (transmitted_speed * knots_to_meterpersecond)) {
mm->speedUnreliable = +1;
}
}
// plus distance covered at the given speed for the elapsed time + 0.2 seconds.
range += (((float) elapsed + 200.0f) * (1.0f / 1000.0f)) * (speed * (1852.0f / 3600.0f));
inrange = (distance <= range);
// don't allow going backwards in the air contrary to good track information
// when only a short time has elapsed
// when the receiverId differs
// this mostly happens due to static range allowed
if (!surface && a->gs > 10 && track_diff > 135 && elapsed < 2 * SECONDS && trackDataAge(now, &a->track_valid) < 2 * SECONDS && a->receiverId != mm->receiverId) {
inrange = 0;
}
float backInTimeSeconds = 0;
if (!inrange && a->gs > 10 && track_diff > 135 && trackDataAge(now, &a->gs_valid) < 10 * SECONDS) {
backInTimeSeconds = distance / (a->gs * (1852.0f / 3600.0f));
}
if (!Modes.userLocationValid && (inrange || override)) {
if (receiverPositionReceived(a, mm, lat, lon, now) == RECEIVER_RANGE_BAD) {
// far outside receiver area
receiverRangeExceeded = 1;
}
}
if (!Modes.userLocationValid && !override && mm->source == SOURCE_ADSB) {
if (!receiverRangeExceeded && !inrange
&& (distance - range > 800 || backInTimeSeconds > 3) && track_diff > 45
&& a->pos_reliable_odd >= Modes.position_persistence * 3 / 4
&& a->pos_reliable_even >= Modes.position_persistence * 3 / 4
&& a->trackUnreliable < 3
) {
struct receiver *r = receiverBad(mm->receiverId, a->addr, now);
if (r && Modes.debug_garbage && r->badCounter > 6) {
fprintf(stderr, "hex: %06x id: %016"PRIx64" #good: %6d #bad: %3.0f trackDiff: %3.0f: %7.2fkm/%7.2fkm in %4.1f s, max %4.0f kt\n",
a->addr, r->id, r->goodCounter, r->badCounter,
track_diff,
distance / 1000.0,
range / 1000.0,
elapsed / 1000.0,
speed
);
}
}
}
if (
(
((!inrange && track_diff < 160) || (!surface && (a->speedUnreliable > 8 || a->trackUnreliable > 8)))
&& source == a->position_valid.source && source > SOURCE_MLAT && (Modes.debug_cpr || Modes.debug_speed_check)
)
|| (a->addr == Modes.cpr_focus && source >= a->position_valid.source)
|| (Modes.debug_maxRange && track_diff > 90)
|| (receiverRangeExceeded && Modes.debug_receiverRangeLimit)
) {
if (uat2esnt_duplicate(now, a, mm) || (!inrange && !override && mm->in_disc_cache) || mm->garbage) {
// don't show debug
} else {
char *failMessage;
if (inrange) {
failMessage = "pass";
} else if (override) {
failMessage = "ovrd";
} else if (receiverRangeExceeded) {
failMessage = "RcvR";
} else {
failMessage = "FAIL";
}
char uuid[32]; // needs 18 chars and null byte
sprint_uuid1(mm->receiverId, uuid);
fprintTime(stderr, now);
fprintf(stderr, " %06x R%3.1f|%3.1f %s %s %s %s %4.0f%%%2ds%2dt %3.0f/%3.0f td %3.0f %8.3fkm in%4.1fs, %4.0fkt %11.6f,%11.6f->%11.6f,%11.6f biT %4.1f s %s rId %s\n",
a->addr,
a->pos_reliable_odd, a->pos_reliable_even,
mm->cpr_odd ? "O" : "E",
cpr_local == CPR_LOCAL ? "L" : (cpr_local == CPR_GLOBAL ? "G" : "S"),
(surface ? "S" : "A"),
failMessage,
fmin(9001.0, 100.0 * distance / range),
a->speedUnreliable,
a->trackUnreliable,
track,
calc_track,
track_diff,
fmin(9001.0, distance / 1000.0),
elapsed / 1000.0,
fmin(9001.0, distance / elapsed * 1000.0 / 1852.0 * 3600.0),
oldLat, oldLon, lat, lon,
backInTimeSeconds, source_string(mm->source), uuid);
}
}
// override, this allows for printing stuff instead of returning
if (override) {
if (!inrange) {
a->lastOverrideTs = now;
}
inrange = override;
}
if (receiverRangeExceeded && Modes.netReceiverId) {
mm->pos_receiver_range_exceeded = 1;
inrange = 0; // far outside receiver area
mm->pos_ignore = 1;
mm->pos_bad = 1;
}
return inrange;
}
/* debug code for surface CPR decoding ... might be useful and reduce typing at some point
if (Modes.debug_receiver && Modes.debug_speed_check && receiver && a->seen_pos
&& *lat < 89
&& *lat > -89
&& (fabs(a->lat - *lat) > 35 || fabs(a->lon - *lon) > 35 || fabs(reflat - *lat) > 35 || fabs(reflon - *lon) > 35)
&& !bogus_lat_lon(*lat, *lon)
) {
//struct receiver *r = receiver;
//fprintf(stderr, "id: %016"PRIx64" #pos: %9"PRIu64" lat min:%4.0f max:%4.0f lon min:%4.0f max:%4.0f\n",
// r->id, r->positionCounter,
// r->latMin, r->latMax,
// r->lonMin, r->lonMax);
int sc = speed_check(a, mm->source, *lat, *lon, mm, CPR_GLOBAL);
fprintf(stderr, "%s%06x surface CPR rec. ref.: %4.0f %4.0f sc: %d result: %7.2f %7.2f --> %7.2f %7.2f\n",
(a->addr & MODES_NON_ICAO_ADDRESS) ? "~" : " ",
a->addr, reflat, reflon, sc, a->lat, a->lon, *lat, *lon);
}
if (Modes.debug_receiver && receiver && a->addr == Modes.cpr_focus)
fprintf(stderr, "%06x using reference: %4.0f %4.0f result: %7.2f %7.2f\n", a->addr, reflat, reflon, *lat, *lon);
*/
static int doGlobalCPR(struct aircraft *a, struct modesMessage *mm, double *lat, double *lon, unsigned *nic, unsigned *rc) {
int result;
int fflag = mm->cpr_odd;
int surface = (mm->cpr_type == CPR_SURFACE);
struct receiver *receiver;
double reflat, reflon;
// derive NIC, Rc from the worse of the two position
// smaller NIC is worse; larger Rc is worse
*nic = (a->cpr_even_nic < a->cpr_odd_nic ? a->cpr_even_nic : a->cpr_odd_nic);
*rc = (a->cpr_even_rc > a->cpr_odd_rc ? a->cpr_even_rc : a->cpr_odd_rc);
if (surface) {
// surface global CPR
// find reference location
int ref = 0;
if (Modes.userLocationValid) {
reflat = Modes.fUserLat;
reflon = Modes.fUserLon;
ref = 1;
} else if ((receiver = receiverGetReference(mm->receiverId, &reflat, &reflon, a, 0))) {
//function sets reflat and reflon on success, nothing to do here.
ref = 2;
} else if (a->seen_pos && a->surfaceCPR_allow_ac_rel) {
reflat = a->latReliable;
reflon = a->lonReliable;
ref = 3;
} else {
// No local reference, give up
return (-1);
}
result = decodeCPRsurface(reflat, reflon,
a->cpr_even_lat, a->cpr_even_lon,
a->cpr_odd_lat, a->cpr_odd_lon,
fflag,
lat, lon);
double refDistance = greatcircle(reflat, reflon, *lat, *lon, 0);
if (refDistance > 450e3) {
if (0 && (a->addr == Modes.cpr_focus || Modes.debug_cpr)) {
fprintf(stderr, "%06x CPRsurface ref %d refDistance: %4.0f km (%4.0f, %4.0f) allow_ac_rel %d\n", a->addr, ref, refDistance / 1000.0, reflat, reflon, a->surfaceCPR_allow_ac_rel);
}
// change to failure which doesn't decrement reliable
result = -1;
return result;
}
} else {
// airborne global CPR
result = decodeCPRairborne(a->cpr_even_lat, a->cpr_even_lon,
a->cpr_odd_lat, a->cpr_odd_lon,
fflag,
lat, lon);
}
if (result < 0) {
if (!mm->duplicate && (a->addr == Modes.cpr_focus || Modes.debug_cpr) && !inDiscCache(mm->sysTimestamp, a, mm)) {
fprintf(stderr, "CPR: decode failure for %06x (%d): even: %d %d odd: %d %d fflag: %s\n",
a->addr, result,
a->cpr_even_lat, a->cpr_even_lon,
a->cpr_odd_lat, a->cpr_odd_lon,
fflag ? "odd" : "even");
}
return result;
}
// check max range
if (Modes.maxRange > 0 && Modes.userLocationValid) {
mm->receiver_distance = greatcircle(Modes.fUserLat, Modes.fUserLon, *lat, *lon, 0);
if (mm->receiver_distance > Modes.maxRange) {
if (a->addr == Modes.cpr_focus || Modes.debug_bogus) {
fprintf(stdout, "%5llu %5.1f Global range check failed: %06x %.3f,%.3f, max range %.1fkm, actual %.1fkm\n",
(long long) mm->timestamp % 65536,
10 * log10(mm->signalLevel),
a->addr, *lat, *lon, Modes.maxRange / 1000.0, mm->receiver_distance / 1000.0);
}
if (mm->source != SOURCE_MLAT) {
Modes.stats_current.cpr_global_range_checks++;
if (Modes.debug_maxRange) {
showPositionDebug(a, mm, mm->sysTimestamp, *lat, *lon);
}
}
return (-2); // we consider an out-of-range value to be bad data
}
}
// check speed limit
if (!speed_check(a, mm->source, *lat, *lon, mm, CPR_GLOBAL)) {
if (mm->source != SOURCE_MLAT)
Modes.stats_current.cpr_global_speed_checks++;
return -2;
}
return result;
}
static int doLocalCPR(struct aircraft *a, struct modesMessage *mm, double *lat, double *lon, unsigned *nic, unsigned *rc) {
// relative CPR
// find reference location
double reflat, reflon;
double range_limit = 0;
int result;
int fflag = mm->cpr_odd;
int surface = (mm->cpr_type == CPR_SURFACE);
int relative_to = 0; // aircraft(1) or receiver(2) relative
if (fflag) {
*nic = a->cpr_odd_nic;
*rc = a->cpr_odd_rc;
} else {
*nic = a->cpr_even_nic;
*rc = a->cpr_even_rc;
}
int64_t now = mm->sysTimestamp;
if (now < a->seenPosGlobal + 10 * MINUTES && a->localCPR_allow_ac_rel) {
reflat = a->lat;
reflon = a->lon;
if (a->pos_nic < *nic)
*nic = a->pos_nic;
if (a->pos_rc < *rc)
*rc = a->pos_rc;
range_limit = 1852*100; // 100NM
// 100 NM in the 10 minutes of position validity means 600 knots which
// is fast but happens even for commercial airliners.
// It's not a problem if this limitation fails every now and then.
// A wrong relative position decode would require the aircraft to
// travel 360-100=260 NM in the 10 minutes of position validity.
// This is impossible for planes slower than 1560 knots/Mach 2.3 over the ground.
// Thus this range limit combined with the 10 minutes of position
// validity should not provide bad positions (1 cell away).
relative_to = 1;
} else if (!surface && Modes.userLocationValid) {
reflat = Modes.fUserLat;
reflon = Modes.fUserLon;
// The cell size is at least 360NM, giving a nominal
// max range of 180NM (half a cell).
//
// If the receiver range is more than half a cell
// then we must limit this range further to avoid
// ambiguity. (e.g. if we receive a position report
// at 200NM distance, this may resolve to a position
// at (200-360) = 160NM in the wrong direction)
if (Modes.maxRange == 0) {
return (-1); // Can't do receiver-centered checks at all
} else if (Modes.maxRange <= 1852 * 180) {
range_limit = Modes.maxRange;
} else if (Modes.maxRange < 1852 * 360) {
range_limit = (1852 * 360) - Modes.maxRange;
} else {
return (-1); // Can't do receiver-centered checks at all
}
relative_to = 2;
} else {
// No local reference, give up
return (-1);
}
result = decodeCPRrelative(reflat, reflon,
mm->cpr_lat,
mm->cpr_lon,
fflag, surface,
lat, lon);
if (result < 0) {
return result;
}
// check range limit
if (range_limit > 0) {
double range = greatcircle(reflat, reflon, *lat, *lon, 0);
if (range > range_limit) {
if (mm->source != SOURCE_MLAT)
Modes.stats_current.cpr_local_range_checks++;
return (-1);
}
}
// check max range
if (Modes.maxRange > 0 && Modes.userLocationValid) {
mm->receiver_distance = greatcircle(Modes.fUserLat, Modes.fUserLon, *lat, *lon, 0);
if (mm->receiver_distance > Modes.maxRange) {
if (a->addr == Modes.cpr_focus || Modes.debug_bogus) {
fprintf(stdout, "%5llu %5.1f Global range check failed: %06x %.3f,%.3f, max range %.1fkm, actual %.1fkm\n",
(long long) mm->timestamp % 65536,
10 * log10(mm->signalLevel),
a->addr, *lat, *lon, Modes.maxRange / 1000.0, mm->receiver_distance / 1000.0);
}
if (mm->source != SOURCE_MLAT) {
Modes.stats_current.cpr_local_range_checks++;
if (Modes.debug_maxRange) {
showPositionDebug(a, mm, mm->sysTimestamp, *lat, *lon);
}
}
return (-2); // we consider an out-of-range value to be bad data
}
}
// check speed limit
if (!speed_check(a, mm->source, *lat, *lon, mm, CPR_LOCAL)) {
if (mm->source != SOURCE_MLAT)
Modes.stats_current.cpr_local_speed_checks++;
return -2;
}
return relative_to;
}
static int64_t time_between(int64_t t1, int64_t t2) {
if (t1 >= t2)
return t1 - t2;
else
return t2 - t1;
}
static void setPosition(struct aircraft *a, struct modesMessage *mm, int64_t now) {
if (0 && a->addr == Modes.cpr_focus) {
showPositionDebug(a, mm, now, 0, 0);
}
// if we get the same position again but from an inferior source, assume it's delayed and treat as duplicate
if (now < a->seen_pos + 10 * MINUTES && mm->source < a->position_valid.last_source && mm->distance_traveled < 20) {
if (a->addr == Modes.cpr_focus) {
fprintf(stderr, "%06x less than 20 m\n", a->addr);
}
mm->duplicate = 1;
mm->pos_ignore = 1;
}
if (duplicate_check(now, a, mm->decoded_lat, mm->decoded_lon, mm)) {
// don't use duplicate positions
mm->pos_ignore = 1;
}
if (bogus_lat_lon(mm->decoded_lat, mm->decoded_lon)) {
if (0 && (fabs(mm->decoded_lat) >= 90.0 || fabs(mm->decoded_lon) >= 180.0)) {
fprintf(stderr, "%06x lat,lon out of bounds: %.2f,%.2f source: %s\n", a->addr, mm->decoded_lat, mm->decoded_lon, source_enum_string(mm->source));
}
return;
}
// for UAT messages converted by uat2esnt each position becomes a odd / even message pair
// only update the position for the odd message if we've recently seen a reliable position
if (uat2esnt_duplicate(now, a, mm)) {
return;
}
Modes.stats_current.pos_by_type[mm->addrtype]++;
Modes.stats_current.pos_all++;
// mm->pos_bad should never arrive here, handle it just in case
if (mm->cpr_valid && (mm->garbage || mm->pos_bad)) {
Modes.stats_current.pos_garbage++;
return;
}
if (mm->client) {
mm->client->positionCounter++;
}
if (mm->duplicate) {
Modes.stats_current.pos_duplicate++;
return;
}
a->receiverId = mm->receiverId;
if (mm->source != SOURCE_JAERO && mm->distance_traveled >= 100) {
if (mm->calculated_track != -1)
a->calc_track = mm->calculated_track;
else
a->calc_track = bearing(a->lat, a->lon, mm->decoded_lat, mm->decoded_lon);
}