nwwautomatic vehicle control and tracking
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AUTOMATIC VEHICLE CONTROL AND
TRACKING
A PROJECT REPORT
Submitted by
PRIYA JOHNSON
PRIYANKA MOHAN K
REHANA JOSE
in partial fulfillment for the award of the degree
of
BACHELOR OF TECHNOLOGY
IN
ELECTRONICS AND COMMUNICATION ENGINEERING
SREE NARAYANA GURUKULAM COLLEGE OF ENGINEERING
MG UNIVERSITY : KOTTAYAM
MAY 2011
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MG UNIVERSITY: KOTTAYAM
BONAFIDE CERTIFICATE
Certified that this project report “AUTOMATIC VEHICLE CONTROL AND
TRACKING”
is the bonafide work of “PRIYA JOHNSON,PRIYANKA
MOHAN,REHANA JOSE” who carried out the project work under my
supervision.
<<Signature of the Head of the Department>> <<Signature of theSupervisor>>SIGNATURE SIGNATURE
<<Name>> <<Name>>HEAD OF THE DEPARTMENT SUPERVISOR
<<Academic Designation>>
<<Department>> <<Department>>
<<Full address of the Dept & College >> <<Full address of the Dept&College >>
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ABSTRACT
Automatic vehicle control and tracking is a means for automatically
controlling vehicles for the purpose of safety and for determining the
geographic location of the vehicle and transmitting the information
the requester. Automatic control and tracking is a powerful concept over
vehicles as a security measure. This system helps to send messages while the
vehicle is started, using GSM and can locate the current position of vehicle
using GPS. The controlling and tracking messages are sent through a cell
phone. If the owner itself or somebody whom he knows is starting the
vehicle no actions are taken. On the other hand, If a stranger has started
the car without the awareness of the owner, the owner can send a message
to stop the vehicle via GSM. He can also locate the current position of the
vehicle via GPS. Here we are using PIC as the microcontroller which is
programmed accordingly. This system can also be used to track the
vehicle. Suppose somebody with our consent has taken the vehicle and we
want to know the current location of the vehicle, then send a message, say,
TRACK via GSM from owners cell phone. The PIC will detect the message
and accordingly collect the location details through GPS
and send the same to owner’s cell phone via GSM.
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TABLE OF CONTENTS
CHAPTER NO. TITLE PAGE
NO.
ABSTRACT iii
LIST OF TABLE xvi
LIST OF FIGURES xviii
LIST OF SYMBOLS xxvii
1. INTRODUCTION 1
1.1 GENERAL 1
1.2 . . . . . . . . . . . . . 2
1.2.1 General 5
1.2.2 . . . . . . . . . . . 12
1.2.2.1 General 19
1.2.2.2 . . . . . . . . . . 25
1.2.2.3 . . . . . . . . . . 29
1.2.3 . . . . . . . . . . . . 30
1.3 . . . . . . . . . . .. . . . . . . 45
1.4 . . . . . . . . . . . . . . . . . . 58
2. LITERATURE REVIEW 69
2.1 GENERAL 75
2.2 . . . . . . . . . . 99
2.2 ……………. 100
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LIST OF TABLES
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LIST OF FIGURES
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LIST OF SYMBOL ABBREVIATIONS
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BLOCK DIAGRAM
EXPLANATION
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The system consist of mainly four modules. GSM, GPS, PIC and LCD. TheLED in block diagram represents the spark plug of the vehicle. PIC is
programmed in such a way that when LED is ON (which represents the ignition
of spark plug) a message is sent to the preset number.When supply is given to the LED it gets turned on. This
shows the ignition of spark plug. When this happens a
message “VEHICLE IS TURNED ON” will be sent to a preset
number via GSM from the SIM loaded in the GSM modem.
On receiving this message two actions can be done
• Stop
• Track
If the vehicle is started by a stranger then the owner can stop thevehicle on receiving the message. This can be done by sending amessage “STOP” to the sim loaded in GSM modem. On receivingthis message the supply to the spark plug is cut off stopping thevehicle. Simultaneously the current location of the vehicle isretrieved from the GPS in the form of latitude and longitude. Thena message “VEHICLE IS TURNED OFF “along with locationdetails will be sent to the preset number.
If we want to track the vehicle then a message “TRACK” is sentto the sim loaded in GSM modem. On receiving this message thecurrent location of the vehicle in the form of latitude andlongitude is retrieved from GPS. This is sent to the preset number.
Here the reception function is done by both GPS and GSM. FromGPS we receive data about the location and from GPS we receivemessages. So at a time either GSM or GPS will be performingreception. A relay is used to switch between these modules whilereception. That is, at a time the relay will connect either GSM or GPS to the PIC.
GSM
Global System for Mobile Communications, or GSM (originally from Groupe
Spécial Mobile), is the world's most popular standard for mobile telephone
systems. The GSM Association estimates that 80% of the global mobile market
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uses the standard. GSM is used by over 1.5 billion people across more than 212
countries and territories. This ubiquity means that subscribers can use their
phones throughout the world, enabled by international roaming arrangements
between mobile network operators. GSM differs from its predecessor
technologies in that both signaling and speech channels are digital, and thus
GSM is considered a second generation (2G) mobile phone system. This also
facilitates the wide-spread implementation of data communication applications
into the system.
The GSM standard has been an advantage to both consumers, who may benefit
from the ability to roam and switch carriers without replacing phones, and also
to network operators, who can choose equipment from many GSM equipment
vendors. GSM also pioneered low-cost implementation of the short message
service (SMS), also called text messaging, which has since been supported on
other mobile phone standards as well. The standard includes a worldwide
emergency telephone number feature (112).
Newer versions of the standard were backward-compatible with the original
GSM system. For example, Release '97 of the standard added packet data
capabilities by means of General Packet Radio Service (GPRS). Release '99
introduced higher speed data transmission using Enhanced Data Rates for GSM
Evolution (EDGE).
Technical details
GSM is a cellular network, which means that mobile phones connect to it by
searching for cells in the immediate vicinity. There are five different cell sizes in
a GSM network—macro, micro, pico, femto and umbrella cells. The coverage
area of each cell varies according to the implementation environment. Macro
cells can be regarded as cells where the base station antenna is installed on a
mast or a building above average roof top level. Micro cells are cells whose
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antenna height is under average roof top level; they are typically used in urban
areas. Picocells are small cells whose coverage diameter is a few dozen metres;
they are mainly used indoors. Femtocells are cells designed for use in
residential or small business environments and connect to the service provider’s
network via a broadband internet connection. Umbrella cells are used to cover
shadowed regions of smaller cells and fill in gaps in coverage between those
cells.
Cell horizontal radius varies depending on antenna height, antenna gain and
propagation conditions from a couple of hundred meters to several tens of
kilometres. The longest distance the GSM specification supports in practical use
is 35 kilometres (22 mi). There are also several implementations of the concept
of an extended cell,[11] where the cell radius could be double or even more,
depending on the antenna system, the type of terrain and the timing advance.
Indoor coverage is also supported by GSM and may be achieved by using an
indoor picocell base station, or an indoor repeater with distributed indoor
antennas fed through power splitters, to deliver the radio signals from an
antenna outdoors to the separate indoor distributed antenna system. These are
typically deployed when a lot of call capacity is needed indoors; for example, in
shopping centers or airports. However, this is not a prerequisite, since indoor
coverage is also provided by in-building penetration of the radio signals from
any nearby cell.
The modulation used in GSM is Gaussian minimum-shift keying (GMSK), akind of continuous-phase frequency shift keying. In GMSK, the signal to be
modulated onto the carrier is first smoothed with a Gaussian low-pass filter
prior to being fed to a frequency modulator , which greatly reduces the
interference to neighboring channels (adjacent-channel interference).
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GSM carrier frequencies
GSM networks operate in a number of different carrier frequency ranges
(separated into GSM frequency ranges for 2G and UMTS frequency bands for
3G), with most 2G GSM networks operating in the 900 MHz or 1800 MHz
bands. Where these bands were already allocated, the 850 MHz and 1900 MHz
bands were used instead (for example in Canada and the United States). In rare
cases the 400 and 450 MHz frequency bands are assigned in some countries
because they were previously used for first-generation systems.
Most 3G networks in Europe operate in the 2100 MHz frequency band.
Regardless of the frequency selected by an operator, it is divided into timeslots
for individual phones to use. This allows eight full-rate or sixteen half-rate
speech channels per radio frequency. These eight radio timeslots (or eight burst
periods) are grouped into a TDMA frame. Half rate channels use alternate
frames in the same timeslot. The channel data rate for all 8 channels is
270.833 kbit/s, and the frame duration is 4.615 ms.
The transmission power in the handset is limited to a maximum of 2 watts in
GSM850/900 and 1 watt in GSM1800/1900.
Voice codecs
GSM has used a variety of voice codecs to squeeze 3.1 kHz audio into between
5.6 and 13 kbit/s. Originally, two codecs, named after the types of data channel
they were allocated, were used, called Half Rate (5.6 kbit/s) and Full Rate
(13 kbit/s). These used a system based upon linear predictive coding (LPC). In
addition to being efficient with bitrates, these codecs also made it easier to
identify more important parts of the audio, allowing the air interface layer to
prioritize and better protect these parts of the signal.
GSM was further enhanced in 1997[12] with the Enhanced Full Rate (EFR)
codec, a 12.2 kbit/s codec that uses a full rate channel. Finally, with the
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development of UMTS, EFR was refactored into a variable-rate codec called
AMR-Narrowband, which is high quality and robust against interference when
used on full rate channels, and less robust but still relatively high quality when
used in good radio conditions on half-rate channels.
Network structure
The structure of a GSM network
The network is structured into a number of discrete sections:
• The Base Station Subsystem (the base stations and their controllers).
• the Network and Switching Subsystem (the part of the network most
similar to a fixed network). This is sometimes also just called the core
network.
• The GPRS Core Network (the optional part which allows packet based
Internet connections).
• The Operations support system (OSS) for maintenance of the network.
Subscriber Identity Module (SIM)
One of the key features of GSM is the Subscriber Identity Module, commonly
known as a SIM card. The SIM is a detachable smart card containing the user's
subscription information and phone book. This allows the user to retain his or
her information after switching handsets. Alternatively, the user can also change
operators while retaining the handset simply by changing the SIM. Some
operators will block this by allowing the phone to use only a single SIM, or only
a SIM issued by them; this practice is known as SIM locking.
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Global Positioning System
The Global Positioning System (GPS) is a space-based global navigation
satellite system (GNSS) that provides reliable location and time information in
all weather and at all times and anywhere on or near the Earth when and where
there is an unobstructed line of sight to four or more GPS satellites. It is
maintained by the United States government and is freely accessible by anyone
with a GPS receiver.
The GPS project was developed in 1973 to overcome the limitations of previous
navigation systems,[1] integrating ideas from several predecessors, including a
number of classified engineering design studies from the 1960s. GPS was
created and realized by the U.S. Department of Defense (USDOD) and was
originally run with 24 satellites. It became fully operational in 1994.
In addition to GPS, other systems are in use or under development. The Russian
GLObal NAvigation Satellite System (GLONASS) was in use by the Russian
military only until it was made fully available to civilians in 2007. There are
also the planned Chinese Compass navigation system and the European Union's
Galileo positioning system.
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Basic concept of GPS
A GPS receiver calculates its position by precisely timing the signals sent by
GPS satellites high above the Earth. Each satellite continually transmits
messages that include
• the time the message was transmitted
• precise orbital information (the ephemeris)
• The general system health and rough orbits of all GPS satellites (the
almanac).
The receiver uses the messages it receives to determine the transit time of each
message and computes the distance to each satellite. These distances along with
the satellites' locations are used with the possible aid of trilateration, depending
on which algorithm is used, to compute the position of the receiver. This
position is then displayed, perhaps with a moving map display or latitude and
longitude; elevation information may be included. Many GPS units show
derived information such as direction and speed, calculated from position
changes.
Three satellites might seem enough to solve for position since space has three
dimensions and a position near the Earth's surface can be assumed. However,
even a very small clock error multiplied by the very large speed of light — the
speed at which satellite signals propagate — results in a large positional error.
Therefore receivers use four or more satellites to solve for the receiver's location
and time. The very accurately computed time is effectively hidden by most GPS
applications, which use only the location. A few specialized GPS applications
do however use the time; these include time transfer , traffic signal timing, and
synchronization of cell phone base stations.
Although four satellites are required for normal operation, fewer apply in
special cases. If one variable is already known, a receiver can determine its
position using only three satellites. For example, a ship or aircraft may have
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known elevation. Some GPS receivers may use additional clues or assumptions
(such as reusing the last known altitude, dead reckoning, inertial navigation, or
including information from the vehicle computer) to give a less accurate
(degraded) position when fewer than four satellites are visible.
Position calculation introduction
To provide an introductory description of how a GPS receiver works, error
effects are deferred to a later section. Using messages received from a minimum
of four visible satellites, a GPS receiver is able to determine the times sent and
then the satellite positions corresponding to these times sent. The x, y, and z
components of position, and the time sent, are designated as where the subscript
i is the satellite number and has the value 1, 2, 3, or 4. Knowing the indicated,
or uncorrected, time the message was received, the GPS receiver can compute
the uncorrected transit time of the message as . Assuming the message traveled
at the speed of light, c, the uncorrected distance traveled or pseudo range, can
be computed as .A satellite's position and pseudo range define a sphere, centered on the satellite
with radius equal to the pseudo range. The position of the receiver is somewhere
on the surface of this sphere. Thus with four satellites, the indicated position of
the GPS receiver is at or near the intersection of the surfaces of four spheres. In
the ideal case of no errors, the GPS receiver would be at a precise intersection
of the four surfaces.If the surfaces of two spheres intersect at more than one point, they intersect in a
circle. The article trilateration shows this mathematically. A figure, Two Sphere
Surfaces Intersecting in a Circle, is shown below. Two points where the
surfaces of the spheres intersect are clearly shown in the figure. The distance
between these two points is the diameter of the circle of intersection.
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Two sphere surfaces intersecting in a circle
The intersection of a third spherical surface with the first two will be its
intersection with that circle; in most cases of practical interest, this means they
intersect at two points.[31] Another figure, Surface of Sphere Intersecting a
Circle (not a solid disk) at Two Points, illustrates the intersection. The two
intersections are marked with dots. Again the article trilateration clearly shows
this mathematically.
Surface of sphere intersecting a circle (not a solid disk) at two points
For automobiles and other near-earth vehicles, the correct position of the GPS
receiver is the intersection closest to the Earth's surface. For space vehicles, the
intersection farthest from Earth may be the correct one.
The correct position for the GPS receiver is also the intersection closest to the
surface of the sphere corresponding to the fourth satellite.
Structure
The current GPS consists of three major segments. These are the space segment
(SS), a control segment (CS), and a user segment (U.S.). The U.S. Air Force
develops, maintains, and operates the space and control segments. GPS
satellites broadcast signals from space, and each GPS receiver uses these signals
to calculate its three-dimensional location (latitude, longitude, and altitude) and
the current time.
The space segment is composed of 24 to 32 satellites in medium Earth orbit and
also includes the payload adapters to the boosters required to launch them into
orbit. The control segment is composed of a master control station, an alternate
master control station, and a host of dedicated and shared ground antennas and
monitor stations. The user segment is composed of hundreds of thousands of
U.S. and allied military users of the secure GPS Precise Positioning Service,
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and tens of millions of civil, commercial, and scientific users of the Standard
Positioning Service (see GPS navigation devices).
Space segmentThe space segment (SS) is composed of the orbiting GPS satellites or Space
Vehicles (SV) in GPS parlance. The GPS design originally called for 24 SVs,
eight each in three circular orbital planes. But this was modified to six planes
with four satellites each.] The orbital planes are centered on the Earth, not
rotating with respect to the distant stars.] The six planes have approximately 55°
inclination (tilt relative to Earth's equator ) and are separated by 60° right
ascension of the ascending node (angle along the equator from a reference point
to the orbit's intersection). The orbits are arranged so that at least six satellites
are always within line of sight from almost everywhere on Earth's surface. The
result of this objective is that the four satellites are not evenly spaced (90
degrees) apart within each orbit. In general terms, the angular difference
between satellites in each orbit is 30, 105, 120, and 105 degrees apart which, of course, sum to 360 degrees.
Orbiting at an altitude of approximately 20,200 kilometers (about 12,550 miles
or 10,900 nautical miles; orbital radius of approximately 26,600 km (about
16,500 mi or 14,400 NM)), each SV makes two complete orbits each sidereal
day, repeating the same ground track each day. This was very helpful during
development because even with only four satellites, correct alignment means allfour are visible from one spot for a few hours each day. For military operations,
the ground track repeat can be used to ensure good coverage in combat zones.
As of March 2008, there are 31 actively broadcasting satellites in the GPS
constellation, and two older, retired from active service satellites kept in the
constellation as orbital spares. The additional satellites improve the precision of
GPS receiver calculations by providing redundant measurements. With the
increased number of satellites, the constellation was changed to a no uniform
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arrangement. Such an arrangement was shown to improve reliability and
availability of the system, relative to a uniform system, when multiple satellites
fail. About eight satellites are visible from any point on the ground at any one
time (see animation at right).
A visual example of the GPS constellation in motion with the Earth rotating. Notice how the
number of satellites in view from a given point on the Earth's surface, in this example at 45°N,
changes with time.
Control segment
The control segment is composed of
1. a master control station (MCS),
2. an alternate master control station,
3. four dedicated ground antennas and
4. six dedicated monitor stations
The MCS can also access U.S. Air Force Satellite Control Network (AFSCN)ground antennas (for additional command and control capability) and NGA
( National Geospatial-Intelligence Agency) monitor stations. The flight paths of
the satellites are tracked by dedicated U.S. Air Force monitoring stations in
Hawaii, Kwajalein, Ascension Island, Diego Garcia, Colorado Springs,
Colorado and Cape Canaveral, along with shared NGA monitor stations
operated in England, Argentina, Ecuador, Bahrain, Australia and WashingtonDC. The tracking information is sent to the Air Force Space Command's MCS at
Schriever Air Force Base 25 km (16 miles) ESE of Colorado Springs, which is
operated by the 2nd Space Operations Squadron (2 SOPS) of the U.S. Air Force.
Then 2 SOPS contacts each GPS satellite regularly with a navigational update
using dedicated or shared (AFSCN) ground antennas (GPS dedicated ground
antennas are located at Kwajalein, Ascension Island, Diego Garcia, and Cape
Canaveral). These updates synchronize the atomic clocks on board the satellites
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to within a few nanoseconds of each other, and adjust the ephemeris of each
satellite's internal orbital model. The updates are created by a Kalman filter that
uses inputs from the ground monitoring stations, space weather information, and
various other inputs.
Satellite maneuvers are not precise by GPS standards. So to change the orbit of
a satellite, the satellite must be marked unhealthy, so receivers will not use it in
their calculation. Then the maneuver can be carried out, and the resulting orbit
tracked from the ground. Then the new ephemeris is uploaded and the satellite
marked healthy again.
User segment
The user segment is composed of hundreds of thousands of U.S. and allied
military users of the secure GPS Precise Positioning Service, and tens of
millions of civil, commercial and scientific users of the Standard Positioning
Service. In general, GPS receivers are composed of an antenna, tuned to the
frequencies transmitted by the satellites, receiver-processors, and a highly stableclock (often a crystal oscillator ). They may also include a display for providing
location and speed information to the user. A receiver is often described by its
number of channels: this signifies how many satellites it can monitor
simultaneously. Originally limited to four or five, this has progressively
increased over the years so that, as of 2007, receivers typically have between 12
and 20 channels.
GPS receivers may include an input for differential corrections, using the
RTCM SC-104 format. This is typically in the form of an RS-232 port at
4,800 bit/s speed. Data is actually sent at a much lower rate, which limits the
accuracy of the signal sent using RTCM. Receivers with internal DGPS
receivers can outperform those using external RTCM data. As of 2006, even
low-cost units commonly include Wide Area Augmentation System (WAAS)
receivers.
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Many GPS receivers can relay position data to a PC or other device using the
NMEA 0183 protocol. Although this protocol is officially defined by the
National Marine Electronics Association (NMEA), references to this protocol
have been compiled from public records, allowing open source tools like gpsd
to read the protocol without violating intellectual property laws. Other
proprietary protocols exist as well, such as the SiRF and MTK protocols.
Receivers can interface with other devices using methods including a serial
connection, USB, or Bluetooth
A typical GPS receiver with integrated antenna.
Applications
While originally a military project, GPS is considered a dual-use technology,
meaning it has significant military and civilian applications.
GPS has become a widely deployed and useful tool for commerce, scientific
uses, tracking, and surveillance. GPS's accurate time facilitates everyday
activities such as banking, mobile phone operations, and even the control of
power grids by allowing well synchronized hand-off switching.
Civilian
This antenna is mounted on the roof of a hut containing a scientific experiment needing precise
timing.
Many civilian applications use one or more of GPS's three basic components:
absolute location, relative movement, and time transfer.
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• Cellular telephony: Clock synchronization enables time transfer, which is
critical for synchronizing its spreading codes with other base stations to
facilitate inter-cell handoff and support hybrid GPS/cellular position
detection for mobile emergency calls and other applications. The first
handsets with integrated GPS launched in the late 1990s. The U.S.
Federal Communications Commission (FCC) mandated the feature in
either the handset or in the towers (for use in triangulation) in 2002 so
emergency services could locate 911 callers. Third-party software
developers later gained access to GPS APIs from Nextel upon launch,
followed by Sprint in 2006, and Verizon soon thereafter.
• Disaster relief /emergency services: Depend upon GPS for location and
timing capabilities.
• Geofencing: Vehicle tracking systems, person tracking systems, and pet
tracking systems use GPS to locate a vehicle, person, or pet. These
devices are attached to the vehicle, person, or the pet collar. The
application provides continuous tracking and mobile or Internet updates
should the target leave a designated area.[47]
• Geotagging: Applying location coordinates to digital objects such as
photographs and other documents for purposes such as creating map
overlays.
• GPS Aircraft Tracking
• GPS tours: Location determines what content to display; for instance,
information about an approaching point of interest.
• Map-making: Both civilian and military cartographers use GPS
extensively.
• Navigation: Navigators value digitally precise velocity and orientation
measurements.
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• Phasor measurement units: GPS enables highly accurate timestamping of
power system measurements, making it possible to compute phasors.
• Recreation: For example, geocaching, geodashing, GPS drawing and
waymarking.
• Surveying: Surveyors use absolute locations to make maps and determine
property boundaries.
• Tectonics: GPS enables direct fault motion measurement in earthquakes.
Military
As of 2009, military applications of GPS include:• Navigation: GPS allows soldiers to find objectives, even in the dark or in
unfamiliar territory, and to coordinate troop and supply movement. In the
United States armed forces, commanders use the Commanders Digital
Assistant and lower ranks use the Soldier Digital Assistant .
• Target tracking: Various military weapons systems use GPS to track
potential ground and air targets before flagging them as hostile.[citation needed ]
These weapon systems pass target coordinates to precision-guided
munitions to allow them to engage targets accurately. Military aircraft,
particularly in air-to-ground roles, use GPS to find targets (for example,
gun camera video from AH-1 Cobras in Iraq show GPS co-ordinates that
can be viewed with special software.)
•
Missile and projectile guidance: GPS allows accurate targeting of variousmilitary weapons including ICBMs, cruise missiles and precision-guided
munitions. Artillery projectiles. Embedded GPS receivers able to
withstand accelerations of 12,000 g or about 118 km/s2 have been
developed for use in 155 millimeters (6.1 in) howitzers.
• Search and Rescue: Downed pilots can be located faster if their position
is known.
• Reconnaissance: Patrol movement can be managed more closely.
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GPS satellites carry a set of nuclear detonation detectors consisting of an optical
sensor (Y-sensor), an X-ray sensor, a dosimeter, and an electromagnetic pulse
(EMP) sensor (W-sensor), that form a major portion of the United States
Nuclear Detonation Detection System
Communication
The navigational signals transmitted by GPS satellites encode a variety of
information including satellite positions, the state of the internal clocks, and the
health of the network. These signals are transmitted on two separate carrier
frequencies that are common to all satellites in the network. Two different
encodings are used, a public encoding that enables lower resolution navigation,
and an encrypted encoding used by the U.S. military.
Message format
GPS message
format
Subframes Description
1Satellite clock,
GPS time relationship
2–3Ephemeris
(precise satellite orbit)
4–5
Almanac component
(satellite network synopsis,
error correction)
Each GPS satellite continuously broadcasts a navigation message at a rate of 50
bits per second (see bitrate). Each complete message is composed of 30-second
frames, distinct groupings of 1,500 bits of information. Each frame is further
subdivided into 5 subframes of length 6 seconds and with 300 bits each. Each
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subframe contains 10 words of 30 bits with length 0.6 seconds each. Each
30 second frame begins precisely on the minute or half minute as indicated by
the atomic clock on each satellite.
The first part of the message encodes the week number and the time within the
week, as well as the data about the health of the satellite. The second part of the
message, the ephemeris, provides the precise orbit for the satellite. The last part
of the message, the almanac, contains coarse orbit and status information for all
satellites in the network as well as data related to error correction.
All satellites broadcast at the same frequencies. Signals are encoded using code
division multiple access (CDMA) allowing messages from individual satellites
to be distinguished from each other based on unique encodings for each satellite
(that the receiver must be aware of). Two distinct types of CDMA encodings are
used: the coarse/acquisition (C/A) code, which is accessible by the general
public, and the precise (P) code, that is encrypted so that only the U.S. military
can access it.
The ephemeris is updated every 2 hours and is generally valid for 4 hours, with
provisions for updates every 6 hours or longer in non-nominal conditions. The
almanac is updated typically every 24 hours. Additionally data for a few weeks
following is uploaded in case of transmission updates that delay data upload.
Satellite frequencies
GPS frequency
overview
Band Frequency Description
L1 1575.42 MHz
Course-acquisition (C/A) and encrypted
precision P(Y) codes, plus the L1
civilian (L1C) and military (M) codes on
future Block III satellites.
L2 1227.60 MHz P(Y) code, plus the L2C and military
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codes on the Block IIR-M and newer
satellites.
L3 1381.05 MHz
Used for nuclear detonation (NUDET)
detection.
L4 1379.913 MHzBeing studied for additional ionospheric
correction.
L5 1176.45 MHzProposed for use as a civilian safety-of-
life (SoL) signal.
All satellites broadcast at the same two frequencies, 1.57542 GHz (L1 signal)
and 1.2276 GHz (L2 signal). The satellite network uses a CDMA spread-
spectrum technique where the low-bitrate message data is encoded with a high-
rate pseudo-random (PRN) sequence that is different for each satellite. The
receiver must be aware of the PRN codes for each satellite to reconstruct the
actual message data. The C/A code, for civilian use, transmits data at
1.023 million chips per second, whereas the P code, for U.S. military use,
transmits at 10.23 million chips per second. The L1 carrier is modulated by both
the C/A and P codes, while the L2 carrier is only modulated by the P code. The
P code can be encrypted as a so-called P(Y) code that is only available to
military equipment with a proper decryption key. Both the C/A and P(Y) codes
impart the precise time-of-day to the user.
The L3 signal at a frequency of 1.38105 GHz is used by the United States
Nuclear Detonation (NUDET) Detection System (USNDS) to detect, locate, and
report nuclear detonations (NUDETs) in the Earth's atmosphere and near space.
One usage is the enforcement of nuclear test ban treaties.
The L4 band at 1.379913 GHz is being studied for additional ionospheric
correction.
The L5 frequency band at 1.17645 GHZ was added in the process of GPS
modernization. This frequency falls into an internationally protected range for
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aeronautical navigation, promising little or no interference under all
circumstances. The first Block IIF satellite that would provide this signal is set
to be launched in 2009. The L5 consists of two carrier components that are in
phase quadrature with each other. Each carrier component is bi-phase shift key
(BPSK) modulated by a separate bit train.
A waiver has recently been granted to LightSquared to operate a terrestrial
broadband service in the L1 band. There is some concern that this will seriously
degrade the GPS signal for many consumer uses.
Demodulation and decoding
Demodulating and Decoding GPS Satellite Signals using the Coarse/Acquisition Gold code.
Because all of the satellite signals are modulated onto the same L1 carrier
frequency, the signals must be separated after demodulation. This is done by
assigning each satellite a unique binary sequence known as a Gold code. The
signals are decoded after demodulation using addition of the Gold codes
corresponding to the satellites monitored by the receiver.
If the almanac information has previously been acquired, the receiver picks the
satellites to listen for by their PRNs, unique numbers in the range 1 through 32.
If the almanac information is not in memory, the receiver enters a search mode
until a lock is obtained on one of the satellites. To obtain a lock, it is necessarythat there be an unobstructed line of sight from the receiver to the satellite. The
receiver can then acquire the almanac and determine the satellites it should
listen for. As it detects each satellite's signal, it identifies it by its distinct
C/A code pattern. There can be a delay of up to 30 seconds before the first
estimate of position because of the need to read the ephemeris data.
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Processing of the navigation message enables the determination of the time of
transmission and the satellite position at this time. For more information see
Demodulation and Decoding, Advanced.
PROGRAM
ALGORITHM
1.LCD is initialized.
2.project name is diplayed on LCD.
3.USART is initialized.
4.GSM is initialized and is displayed on LCD.5.Supply is given to LED (RC3=1).
6.Message “vehicle is on” is send to a mobile number.And is also diplayed on
LCD.
7.Received message is saved.
8.If the message is “track”, “tracking…..” is displayed on LCD.
9.Latitude and longitude of position is sent to mobile and is also displayed on
LCD.
10.IF the message is “stop”,supply to LED is cut off.
11.A message “vehicle engine is turned off ” is sent to mobile and is also
displayed on LCD.
12.Also the location is sent to mobile and is displayed on LCD.
13.IF any other messages,a message “wrong command ” is sent to mobile and
is also displayed on LCD.
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PROGRAM
#include"pic.h"#include"delay.h"#include"usart.h"#include"gsmreceive.h"#include"gsmsend.h"#include"lcd_4.h"
void flags(void);void read(void);void check();char nn,q,t;unsigned char bank1 inbox[10];unsigned char bank1 recmob[14];char bank1 pp;char jj;
void main(){char a,b,c,i,d;
TRISC0=0;TRISC2=1;TRISC3=0;RC0=0;RC2=0;
RC3=0;lcd_init();cmdwrt(0x01);cmdwrt(0x80);LCD_string("VEHICLE TRACKING");usart_init();gsm_init();cmdwrt(0x01);cmdwrt(0x80);
LCD_string("GSM INITIALIZED");DelayMs(250);
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DelayMs(250);DelayMs(250);DelayMs(250);DelayMs(250);
DelayMs(250);DelayMs(250);DelayMs(250);DelayMs(250);DelayMs(250);
while(RC2==0);
RC3=1;
cmdwrt(0xC0);
LCD_string(" VEHICLE IS ON ");
usart_string("AT+CMGS=\"+9495302630\"");
usart_trx(0x0D);
DelayMs(5);
usart_trx(0x0A);
DelayMs(50);
usart_string("Vehicle is turned ON!!");
usart_trx(0x0D);
DelayMs(5);
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usart_trx(0x1A);
DelayMs(50);
usart_trx(0x0D);
DelayMs(5);
usart_trx(0x0A);
DelayMs(50);
gsm_init();
while(1){
cmdwrt(0x01);
cmdwrt(0x80);
LCD_string("VEHICLE TRACKING");
cmdwrt(0xC0);
LCD_string(" WELCOME ");
mess_recv();
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for(i=0;i<10;i++) inbox[i]=0;
for(i=0;i<14;i++) recmob[i]=0;
}}
Delay fn
#include
"delay.h"
voidDelayMs(unsigned char cnt){#if XTAL_FREQ <= 2MHZ
do {
DelayUs(996);
} while(--cnt);#endif
#if XTAL_FREQ > 2MHZ
unsigned char i;
do {
i = 4;
do {
DelayUs(250);
} while(--i);
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} while(--cnt);#endif }
GPS
#include"pic.h"#include"delay.h"#include"usart.h"#include"gps.h"#include"lcd_4.h"
char day1;char day2;char mon1;char mon2;char yer1;char yer2;char hr1;char hr2;char min1;
char min2;
void gps(){char aa,bb,cc,i;char mm;
cmdwrt(0xC0);
LCD_string(" TRACKING.... ");RC0=1;DelayMs(250);BAUD_RATE=0x33;DelayMs(250);
while (usart_rx()!='$');
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while (usart_rx()!='G');
while (usart_rx()!='P'); while (usart_rx()!='R'); while (usart_rx()!='M'); while (usart_rx()!='C'); mm=usart_rx();
hr1=usart_rx();hr2=usart_rx();
min1=usart_rx();min2=usart_rx();
mm=usart_rx();mm=usart_rx();for(aa=0;aa<5;aa++){mm=usart_rx();}
while (usart_rx()!='A');
mm=usart_rx(); for(aa=0;aa<11;aa++)
{latitude[aa]=usart_rx();
}
mm=usart_rx();
for(bb=0;bb<12;bb++){longitude[bb]=usart_rx();
}
for(aa=0;aa<=11;aa++)
{
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mm=usart_rx();
}
day1=usart_rx();day2=usart_rx();mon1=usart_rx();mon2=usart_rx();yer1=usart_rx();yer2=usart_rx();RC0=0;
DelayMs(250);
cmdwrt(0x01);cmdwrt(0x80);LCD_string("LATTITUDE IS:");
cmdwrt(0xC0);
for(aa=0;aa<11;aa++){datwrt(latitude[aa]);
}for(i=0;i<10;i++){DelayMs(250);}cmdwrt(0x01);cmdwrt(0x80);LCD_string("LONGITUDE IS:");
cmdwrt(0xC0);
for(bb=0;bb<11;bb++){datwrt(longitude[bb]);
}DelayMs(250);
BAUD_RATE=0x19;DelayMs(250);
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}
LCD
#include"pic.h"#include"delay.h"#include"lcd_4.h"
void lcd_init(){
unsigned char TRISB=0x00;
TRISA=0X00;
ADCON1=0x07;
cmdwrt(0x28);
cmdwrt(0x28);
cmdwrt(0x28);
cmdwrt(0x06);
cmdwrt(0x0F);
cmdwrt(0x01);
cmdwrt(0x80);return;
}
void cmdwrt(char a){
char c;
c=a;
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a=(a&0xF0)>>4;
PORTB=a;
RA0=0;
RA1=0;
RA2=1;
DelayUs(5);
RA2=0;
DelayUs(1);
a=(c&0x0F);
PORTB=a;
RA0=0;
RA1=0;
RA2=1;
DelayUs(5);
RA2=0;
DelayMs(10);return;
}
void datwrt(char b){
char c;
c=b;
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b=(b&0xF0)>>4;
PORTB=b;
RA0=1;
RA1=0;
RA2=1;
DelayUs(10);
RA2=0;
DelayUs(1);
b=(c&0x0F);
PORTB=b;
RA0=1;
RA1=0;
RA2=1;
DelayUs(10);
RA2=0;
DelayMs(10);return;
}
void LCD_string(const char *DATA){while(*DATA){
datwrt(*DATA);DATA++;
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}
GSM receive
#include"pic.h"#include"delay.h"#include"usart.h"#include"gsmreceive.h"#include"gsmsend.h"#include"string.h"#include"gps.h"#include"lcd_4.h"
void DELAY();extern unsigned char bank1 inbox[10];extern unsigned char bank1 recmob[14];char bank1 latitude[11];char bank1 longitude[12];
char mess_recv(){
int j=0;
unsigned int i,k;
unsigned char l,sp1,sp2,val,x,qq;
cmdwrt(0xC0);
LCD_string(" MESSAGE ");while(usart_rx()!='+');
while(usart_rx()!='C');
while(usart_rx()!='M');
while(usart_rx()!='T');
while(usart_rx()!='I');
while(usart_rx()!=',');
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qq=usart_rx();
//MSG INDEX
usart_string("AT+CMGR=1");
usart_trx(0x0D);DelayMs(5);
usart_trx(0x0A);
while(usart_rx()!='+');
while(usart_rx()!='C');
while(usart_rx()!='M');
while(usart_rx()!='G');
while(usart_rx()!='R');
while(usart_rx()!=',');x=usart_rx();
while(1)
{
x=usart_rx();
if(x=='"')
break;
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else
{
recmob[j]=x;
j++;
continue;
}
break;
}
j=0;
while(usart_rx()!=0x0D);
x=usart_rx();
while(1){
x=usart_rx();if(x==0x0D)
break;else
{
inbox[j]=x;
j++;
continue;
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}
break;}x=usart_rx(); cmdwrt(0xC0);
LCD_string(" MSG RECEIVED ");DELAY();cmdwrt(0xC0);LCD_string(" ");
cmdwrt(0xC0);LCD_string("MSG=");for(i=0;inbox[i]!='\0';i++)
{
datwrt(inbox[i]);}
DELAY();if(strcmp(inbox,"track")==0)
{//
cmdwrt(0xC0);//
LCD_string(" TRACKING.... ");gps();
usart_string("AT+CMGS=\"");
for(i=0;recmob[i]!='\0';i++)
{usart_trx(recmob[i]);
DelayMs(50);
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}usart_string("\"");usart_trx(0x0D);
DelayMs(5);
usart_trx(0x0A);DelayMs(50);usart_string("Vehicle Tracked!!, Location:-");usart_trx(0x0D);DelayMs(5);
usart_trx(0x0A);DelayMs(100);
for(i=0;i<11;i++)
{usart_trx(latitude[i]);
DelayMs(50);}
for(i=0;i<12;i++){
usart_trx(longitude[i]);DelayMs(50);
}
usart_trx(0x0D);
DelayMs(5);usart_trx(0x1A);
DelayMs(50);usart_trx(0x0D);
DelayMs(5);usart_trx(0x0A);
while(usart_rx()!='O');
while(usart_rx()!='K');
usart_string("AT+CMGD=1");usart_trx(0X0D);DelayMs(5);usart_trx(0X0A);DELAY();
}else if(strcmp(inbox,"stop")==0)
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{
cmdwrt(0x01);
cmdwrt(0x80);
LCD_string("WARNING!!!");
cmdwrt(0xC0);
LCD_string("ENGINE HALTED!!");
RC3=0;
gps();usart_string("AT+CMGS=\"");
for(i=0;recmob[i]!='\0';i++){usart_trx(recmob[i]);
DelayMs(50);}
usart_string("\"");
usart_trx(0x0D);DelayMs(5);
usart_trx(0x0A);DelayMs(50);usart_string("Location:- ");usart_trx(0x0D);DelayMs(5);
usart_trx(0x0A);DelayMs(100);
for(i=0;i<11;i++){
usart_trx(latitude[i]);DelayMs(50);
}
for(i=0;i<12;i++)
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{usart_trx(longitude[i]);
DelayMs(50);
}
usart_string(" VEHICLE ENGINE TURNED OFF");usart_trx(0x0D);
DelayMs(5);
usart_trx(0x1A);
DelayMs(50);usart_trx(0x0D);
DelayMs(5);
usart_trx(0x0A);while(usart_rx()!='O');while(usart_rx()!='K');DelayMs(50);
usart_string("AT+CMGD=1");
usart_trx(0X0D);DelayMs(5);usart_trx(0X0A);DELAY();
while(1);}
else{
cmdwrt(0xC0);LCD_string("wrong command!!");usart_string("AT+CMGS=\"");
for(i=0;recmob[i]!='\0';i++){usart_trx(recmob[i]);
DelayMs(50);}
usart_string("\"");usart_trx(0x0D);
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DelayMs(5);usart_trx(0x0A);
DelayMs(50);usart_string("Wrong Command!!");
usart_trx(0x0D);DelayMs(5);
usart_trx(0x1A);DelayMs(50);
usart_trx(0x0D);
DelayMs(5);usart_trx(0x0A);
while(usart_rx()!='O');
while(usart_rx()!='K');DelayMs(50);usart_string("AT+CMGD=1");usart_trx(0X0D);DelayMs(5);usart_trx(0X0A);DELAY();
}cmdwrt(0xC0);LCD_string(" MSG SENT ");
for(i=0;i<12;i++)DelayMs(250);
}void DELAY(){int xxxx;for(xxxx=0;xxxx<32;xxxx++){DelayMs(250);
}}
GSM send#include"pic.h"#include"delay.h"#include"usart.h"
#include"gsmsend.h"#include"gps.h"
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extern char bank1 latitude[11];extern char bank1 longitude[12];void gsm_init()
//GSM Initialisation{
int ccc;
usart_string("AT");
usart_trx(0x0D);
DelayMs(5);
usart_trx(0x0A); DelayMs(100);
usart_string("AT");
usart_trx(0x0D);
DelayMs(5);
usart_trx(0x0A);while(usart_rx()!='O');while(usart_rx()!='K');DelayMs(100);
usart_string("AT");
usart_trx(0x0D);DelayMs(5);
usart_trx(0x0A);while(usart_rx()!='O');while(usart_rx()!='K');DelayMs(100);
usart_string("AT+CMGF=1");
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usart_trx(0x0D);DelayMs(5);
usart_trx(0x0A);
while(usart_rx()!='O');while(usart_rx()!='K');DelayMs(100);
usart_string("AT+CMGD=1");
usart_trx(0x0D);DelayMs(5);
usart_trx(0x0A);while(usart_rx()!='O');while(usart_rx()!='K');DelayMs(100);
usart_string("AT+CMGD=2");
usart_trx(0x0D);
DelayMs(5);
usart_trx(0x0A);
while(usart_rx()!='O');while(usart_rx()!='K');DelayMs(100);
usart_string("AT+CMGD=3");
usart_trx(0x0D);DelayMs(5);
usart_trx(0x0A);while(usart_rx()!='O');while(usart_rx()!='K');DelayMs(100);
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for(ccc=0;ccc<=8;ccc++)
{
DelayMs(250);
}return;}
USART
#include"pic.h"#include"delay.h"#include"usart.h"char e;unsigned int i;/*USART Initialisation*/void usart_init(){TRANSMIT_PIN=CLEAR;RECEIVE_PIN=SET;
BAUD_TYPE=SET;BAUD_RATE=0x19;SERIAL_PORT=SET;RECEIVE_ENABLE=SET;TRANSMIT_ENABLE=SET;}
/* USART transmission function*/
void usart_trx( char xx){TRANSMIT_REGISTER=xx;while(TRANSMIT_FLAG==CLEAR);}
void usart_string(const char *DATA){
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while(*DATA){TRANSMIT_REGISTER=*DATA;while(TRANSMIT_FLAG==CLEAR);
DelayMs(50);DATA++;}return;}
/*USART reception function*/
char usart_rx(){char yy;if(OVER_RUN==1){OVER_RUN=CLEAR;RECEIVE_ENABLE=CLEAR;DelayUs(5);
RECEIVE_ENABLE=SET;}while(RECEIVE_FLAG==CLEAR);yy=RECEIVE_REGISTER;return yy;}
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