First stab at multilateration server. No client, incomplete.

This commit is contained in:
Nick Foster 2012-12-05 11:28:59 -08:00
parent fcb06ef25a
commit e771c21730
2 changed files with 281 additions and 0 deletions

237
apps/mlat_server.py Executable file
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#!/usr/bin/env python
#
# Copyright 2012 Nick Foster
#
# This file is part of gr-air-modes
#
# gr-air-modes 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, or (at your option)
# any later version.
#
# gr-air-modes 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 gr-air-modes; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
import time, os, sys, socket, struct
from string import split, join
from datetime import *
import air_modes
import pickle
import time
import bisect
#simple multilateration server app.
#accepts connections from clients (need a raw_client output thing)
#looks at received messages and then attempts to multilaterate positions
#will not attempt clock synchronization yet; it's up to clients to present
#accurate timestamps. later on we can do clock sync based on ADS-B packets.
#how to store records for quick retrieval?
#the data is really a hash; we use it to find correlated records.
#self._records should be a dict of replies
#so: { <adsbdata>: [{ "addr": "192.168.10.1", "secs": 11, "frac_secs": 0.123456 }, {....}...] ... }
#adsbdata should be an int.
#change this to 0 for ASCII format for debugging. use HIGHEST_PROTOCOL
#for actual use to keep the pickle size down.
pickle_prot = 0
#pickle_prot = pickle.HIGHEST_PROTOCOL
class rx_data:
def __init__(self):
self.secs = 0
self.frac_secs = 0.0
self.data = None
class stamp:
def __init__(self, addr, secs, frac_secs):
self.addr = addr
self.secs = secs
self.frac_secs = frac_secs
def __lt__(self, other):
if self.secs == other.secs:
return self.frac_secs < other.frac_secs
else:
return self.secs < other.secs
def __gt__(self, other):
if self.secs == other.secs:
return self.frac_secs > other.frac_secs
else:
return self.secs > other.secs
def __eq__(self, other):
return self.secs == other.secs and self.frac_secs == other.frac_secs
def __ne__(self, other):
return self.secs != other.secs or self.frac_secs != other.frac_secs
#good to within ms for comparison
def tofloat(self):
return self.secs + self.frac_secs
def ordered_insert(a, item):
a.insert(bisect.bisect_right(a, item), item)
class client_info:
def __init__(self):
self.name = ""
self.latitude = 0.0
self.longitude = 0.0
self.altitude = 0.0
self.offset_secs = 0
self.offset_frac_secs = 0.0
class connection:
def __init__(self, addr, sock, clientinfo):
self.addr = addr
self.sock = sock
self.clientinfo = clientinfo
class mlat_server:
def __init__(self, mypos, port):
self._s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self._s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self._s.bind(('', port))
self._s.listen(1)
self._s.setblocking(0) #nonblocking
self._conns = [] #list of active connections
self._reports = {} #hashed by data
self._lastreport = 0 #used for pruning
self._parser = air_modes.parse(None)
def __del__(self):
self._s.close()
def get_messages(self):
for conn in self._conns:
pkt = None
try:
pkt = conn.sock.recv(1024)
except socket.error:
self._conns.remove(conn)
if not pkt: break
#try:
msglist = pickle.loads(pkt)
for msg in msglist:
#DEBUG: change conn.clientinfo.name to conn.addr for production
st = stamp(conn.clientinfo.name, msg.secs, msg.frac_secs)
if msg.data not in self._reports:
self._reports[msg.data] = []
#ordered insert
ordered_insert(self._reports[msg.data], st)
self._lastreport = st.tofloat()
# for report in self._reports.values():
# for st in report:
# print st.addr, st.secs, st.frac_secs
#except Exception as e:
# print "Invalid message from %s: %s" % (conn.addr, pkt)
# print e
#self.prune()
#prune should delete all reports in self._reports older than 5s.
#how do we get the appropriate time? we either trust the reporting
#stations, or we use UTC.
#if we assume all stations are using UTC, we can prune on UTC, but
#this computer has to be closely synchronized as well
def prune(self):
for report in self._reports:
if self._reports[report][-1].tofloat() - self._lastreport > 5:
self._reports.remove(report)
#return a list of eligible messages for multilateration
#eligible reports are:
#1. bit-identical
#2. from distinct stations (at least 3)
#3. within 0.001 seconds of each other
#traverse the reports for each data pkt (hash) looking for >3 reports
#within 0.001s, then check for unique IPs (this should pass 99% of the time)
#let's break a record for most nested loops. this one goes four deep.
#it's loop-ception!
def get_eligible_reports(self):
groups = []
for data,stamps in self._reports.iteritems():
if len(stamps) > 2: #quick check before we do a set()
stations = set([st.addr for st in stamps])
if len(stations) > 2:
i=0
#it's O(n) since the list is already sorted
#can probably be cleaner and more concise
while(i < len(stamps)):
refstamp = stamps[i].tofloat()
reps = []
while (i<len(stamps)) and (stamps[i].tofloat() < (refstamp + 0.001)):
reps.append(stamps[i])
i+=1
deduped = []
for addr in stations:
for st in reps[::-1]:
if st.addr == addr:
deduped.append(st)
break
if len(deduped) > 2:
groups.append({"data": data, "stamps": deduped})
if len(groups) > 0:
return groups
return None
#issue multilaterated positions
def output(self, msg):
#do something here to compose a message
if msg is not None:
try:
for conn in self._conns[:]: #iterate over a copy of the list
conn.sock.send(msg)
except socket.error:
print "Client %s disconnected" % conn.clientinfo.name
self._conns.remove(conn)
print "Connections: ", len(self._conns)
#add a new connection to the list
def add_pending_conns(self):
try:
conn, addr = self._s.accept()
conn.send("HELO\n") #yeah it's like that
msg = conn.recv(1024)
if not msg:
return
try:
clientinfo = pickle.loads(msg)
except:
print "Invalid pickle received from client"
return
if clientinfo.__class__.__name__ != "client_info":
print "Invalid datatype received from client"
return
conn.send("OK")
self._conns.append(connection(addr[0], conn, clientinfo))
print "New connection from %s: %s" % (addr[0], clientinfo.name)
except socket.error:
pass
if __name__=="__main__":
srv = mlat_server("nothin'", 31337)
while 1:
srv.output("Buttes")
srv.get_messages()
srv.add_pending_conns()
reps = srv.get_eligible_reports()
if reps:
for rep in reps:
print "Report with data %x" % rep["data"]
for st in rep["stamps"]:
print "Stamp from %s: %f" % (st.addr, st.tofloat())
srv.prune()
time.sleep(0.3)

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apps/mlat_test.py Executable file
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#!/usr/bin/env python
#test stuff for mlat server
import socket, pickle, time, random, sys
class rx_data:
secs = 0
frac_secs = 0.0
data = None
class client_info:
def __init__(self):
self.name = ""
self.latitude = 0.0
self.longitude = 0.0
self.altitude = 0.0
self.offset_secs = 0
self.offset_frac_secs = 0.0
info = client_info()
info.name = sys.argv[1]
info.latitude = float(sys.argv[2])
info.longitude = float(sys.argv[3])
info.altitude = 123
info.offset_secs = 0
info.offset_frac_secs = 0.0
data1 = rx_data()
data1.secs = 0
data1.data = int("0x8da81f875857f10eb65b10cb66f3", 16)
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setblocking(1)
sock.connect(("localhost", 31337))
sock.send(pickle.dumps(info))
print sock.recv(1024)
while 1:
time.sleep(0.05)
data1.frac_secs = random.random()
sock.send(pickle.dumps([data1]))
sock.close()
sock = None