GPS Basics - What is GPS?

What is GPS?

The Global Positioning System (GPS) is a navigational system that can pinpoint your location on earth. GPS has its origin as a military project that was conceived in 1973 by the US Department of Defence. In the 1980s GPS was made available for commercial use.

Today the GPS system is made up of 24 satellites (with 3 backup satellites) that orbit the planet. The arrangement of the satellites are such, that at any given time 4 satellites are in line of sight with a GPS receiver anywhere in the world.

GPS Receiver

Even though GPS is a complex technology, its usage is very simple. In order to use GPS all you need is a GPS receiver. The GPS receiver displays its location on the planet in terms of latitude, longitude, height and time. In order to locate its position, the receiver gets signals from at least 4 satellites. In theory using signals from 3 satellites are sufficient, but in practice 4 satellites are used to improve accuracy. The GPS receiver uses a technique called tri-lateration to determine its position in a 3 dimensional space.

GPS receivers have become popular consumer electronic devices in the recent past. Their popularity is so high, nowadays the term GPS is often used to refer to the  receiver.

Unlike a subscription service such as mobile phones and xm satellites radios, the GPS infrastructure is provided free of charge. This means that you don’t pay for any connection or service charges. The primary cost involved is the initial equipment cost.

The GPS receiver does not broadcast its location. It only receives signals from the satellites to calculate its position. This means no one can track your movements using GPS technology, unless the GPS receiver has some built in mechanism to relay it’s location to the user. Electronic Pet Tracking System uses GPS receivers with relaying mechanism to track the pet.

Today, a basic GPS receiver device would have an antenna, a 12 channel receiver that can connect up to 12 satellites, a central processing unit, a LCD display and in some cases a base map of a region.

GPS Navigation Systems, Just more than a receiver

A GPS navigation system is more than a receiver. It has an electronic map stored in the memory. Using the location information obtained via the receiver, a GPS navigation system plots the position of the user in an electronic map using mapping software.

The latitude and longitude coordinates reported by the GPS receiver is know as waypoints. A series of connected waypoints make up a route. As the GPS receiver moves the virtual bread crump trail that is left is known as a track.

A typical GPS navigation system provides the user with very useful features as follows:

  1. The traveling distance between source and destination
  2. Time since departure
  3. Current speed
  4. Average speed for the trip
  5. A bread crump of trail
  6. Distance to destinationEstimated time of arrival

GPS Vendors

Garmin Ltd

Garmin is a leading provider of GPS navigation systems and technology. The company manufactures GPS systems for both the consumer electronics market and the aviation industry. Garmin GPS systems are used for in-car navigation, avionics,  boating, fishing and for other recreational purposes.

TomTom Inc

TomTom is company based in Netherlands, now operating in over 16 countries. The company specializes in providing navigation software and GPS devices for the PDAs and Pocket PCs market. The company is also a dominant player in the in-car GPS market with the TomTom GO series of user friendly portable car navigation systems. TomTom also provides mobile GPS solutions for the smart phones industry.

Thales Navigation

Thales is a leading provider of GPS systems for both professional and consumer market segments. It consumer product range is marketed under the brand name Magellan while its professional solutions are marketed under the brand name of Thales Navigation. In the consumer segment, Thales provide GPS solutions for automotive and recreational markets. In the professional segment, Thales provide surveying, GIS/Mapping and OEM products.


Magellan is the consumer  product brand of Thales Navigation (see above).


Trimble provides integrated GPS navigation solutions.

Lowrance Electronics Inc

Lowrance is a dominant player in the  manufacturing of high quality sports finishing sonar systems. The company has also made its mark in the development of marine, outdoor, aviation and automotive GPS solutions as well as OEM products.


From its humble origins as enterprise in a New Zeeland garage, Navman has grown to become a global company that is in the forefront of GPS technology. Navman provides GPS solutions for marine, in-car, wireless, sporting and commercial use.

ALK Technologies Inc

ALT Technologies is just more than provider of GPS navigation systems. ALK provides routing, mileage and mapping solutions for shipping companies, private fleet and logistics companies. The company also provides decision support systems for major US railways. In addition the company provides container tracking and management systems for ocean transportation companies and barge operators.

Cobra Electronics Corporation

Cobra had its reputation as a leading manufacturer of GMRS/FRS two-way radio, radar detector technology. But now cobra has made an innovative entry into the marine and mobile GPS navigation markets.


Originally an Atlas publisher, DeLorme has become a pioneer in the area of GPS mapping software and technologies for both professional and consumer markets. DeLorme’s expertise in the field of mapping software and geographic information systems has give the company a competitive advantage in the GPS industry. The company has a wide range of GPS solutions for laptops, Palm PCs and Pocket PCs, as well as handheld GPS units.

Pharos Science and Applications Inc

Pharos is a leader in street navigation, specializing in GPS solutions for Pocket PC based PDA systems. The company also provides GPS solutions for the aerospace industry. The company has developed guidance and control technologies for the NASA space shuttle program.


FineDigital is a provider of in-car and personal navigations solutions for the consumer market segment. The company provides bundled integrated GPS solutions that can be used straight out of the box.

Microsoft Corporation

Microsoft has GPS solutions for laptops. There flagship GPS software are Microsoft Streets & Trips (2006) and AutoRoute (2006).

Mio Technology Limited

Mio provides PDA and personal GPS navigation systems for the consumer market.

OnStar Corporation

OnStar is a division of General Motors that provides a number of safety and security services for car equipped with OnStar systems. Example of such services include unlocking you car if you have lost the keys, 24hr road side assistance, track stolen vehicles, providing driving directions etc. OnStar use GPS technology to support it services.

Pioneer Corporation

Consumer electronics giant Pioneer is also involved in manufacturing street navigation GPS system for automobiles.

Sony Corporation

Consumer electronics giant Sony is also involved in manufacturing street navigation GPS system for automobiles.

TeleNav Inc

TeleNav provides GPS street navigation solutions for users of mobile phones, Blackberry wireless devices, Palm Treo and Windows Mobile Phone devices. TeleNav is a subscriptions based service that can work with various mobile phone network carrier services such as Verizon, Nextel,  Cingular etc.

Tripod Data Systems

Tripod is a subsidiary of Trimble. The company specializes in developing software systems for land surveying and construction. The company also produces software and hardware for mobile computing applications. One of  notable products from Tripod is rugged handled computers that can be used in extreme environmental and weather conditions.

Wherify Wireless Inc

Provides various wireless and GPS solutions.

Laptop based Systems

Laptop based GPS Systems

Laptop based GPS systems are relatively cheap compared with other standalone GPS units. In these systems the map and software are loaded into the laptop hard drive. The only accessory that you need is a simple receiver that can connect to your computer (via USB or serial ports).

The mapping software loaded into the computer will be able to perform the navigation. Most laptop systems come bundled with a GPS receiver. Compared with other GPS systems, a laptop system is bulkier.

But the advantage is that you are leveraging the laptop CPU power, memory and hard disk capacity for your navigation needs.

PDA based GPS Systems

PDA based Systems

A PDA which stands for Personal Data Assistant is a hand held device that has trimmed down features of a Personal Computer.

A PDA that uses the Palm OS software is usually known as a Palm Computer, while PDA the uses the Microsoft mobile operating system is called a Pocket PC.

Buying a PDA based GPS system has the added advantages of using the unit as a handled computer for general productivity and entertainment as well a using it as a GPS navigation tool.

If you already own a PDA, you can buy a GPS add on module, thus saving your initial investment in your PDA.

Sports / Training GPS Units

Sports / Training Units

Sports enthusiast or training athletes will find wearable units very useful. These units can be worn in the wrist like watches.

They have many integrate features such as heart rate monitors, lap/racing timers, calorie count monitors, and virtual partner software that allows you to set your workout target and objectives.

Many wearable units come with associated PC software that can be used to plan and analyse your workout information.

In-Car GPS systems

Car GPS systems

Car GPS systems come in two flavours

1. Portable Add-on units

Many people now a days use a portable unit (see above) in automobiles. Most of the portable units come with accessories that allow the user to use them in a vehicle. These accessories include suction cup to attach the unit to the windshield, car power adapter, battery charges, external antennas  and etc.

2. In-dash units

These are top of the range systems that provide a wide selection of features that nicely and tidily integrate with your car electronics. In-dash units are more expensive. They have to be permanently mounted in the car. This means you cannot move unit if you happen to take another vehicle for your next road trip.

In-dash units give a professional look and feel. They have no clutter (like power adapter wires, suction cup etc). One of the main disadvantages of in-dash units is that they are permanently fixed to the car and might be prone to theft.
Double DIN systems

A Double DIN system occupies two bays in your car dash. Since they are fitted inside the bay, they do not project out and less noticeable from the outside. This might prevent the system from being stolen when the car is unattended.

Portable GPS System

Portable Units

Portable GPS units can be used in car or by a pedestrian.

Lower end portable models may have small screen sizes and little memory capacity. Due to their limited memory capacity they can only store maps of a specific region. It may not be possible to store the whole map of a country like the United States. The maps on lower end portable units are usually stored in SD Cards, CD ROMs or in the system’s built memory.

Higher end potable units have larger screens and large memory storage capacity. They typically use a hard drive or DVD disk to store the map software. Most of the high end portable units have other cool integrated features such a MP3 playback capability, xm satellite radio services, picture viewers, audio books and blue tooth integration.

Basic GPS Systems

The basic units are just the plain old receiver with minimal set of features. A basic unit can be bought for around 100 dollars.

These simple devices have the basic functionality of reporting the location in terms of latitude and longitude. They may also have a base map (a very high level map that contains major highways and few Points of Interests) of a region. Basic units have limited processor and memory capacity.

These units are ideal for a person with low budget whom would like to use GPS for basic navigation, educational activities and fun.

GPS Buyer Guide Features

What features to look for when shopping for a GPS system


Your navigation experience depends a great deal on the quality of your electronic maps. Today most of the GPS systems come preloaded with maps. The maps that come preloaded with your system may not be detailed street level maps.

An alternative may be to buy a GPS system without any preloaded maps and to buy the maps separately. If you are going to buy the maps separately make sure you check the cost of the mapping software. Some times buying the mapping software separately might cost you more.

Usually maps can be loaded into your GPS system via USB cables or via storage medias such as SD Cards, CD ROMs or DVD disks. A detailed map of the United States and Canada might take around 2 GB of storage space.

Most GPS system will have a list of points of interests. POIs are likely places that a user might visit. They include places like gas stations, bank machines, hospitals, car parks, and tourist sites.

Display size and display quality

The size of the GPS display screen will have direct impact on its usability. The bigger the screen size, its more easier to read information. A screen with higher resolution (that is more pixels) will enhance clarity.

Antiglare screens are ideal for in-car systems because they are easier to read on a very bright sunny day. Color displays are superior to greyscale units. But on battery operated units they might drain the battery more quickly than a greyscale unit. Also greyscale units are comparatively cheaper than color units.

Quality of the map graphics

Some GPS systems can provide a Bird eyes view of the map. This makes navigation more easier as the roads are shown in a 3 dimensional view.

Touch Screen

Most of the higher-end portable and in-car GPS systems in the market come with a touch screen.  A touch screen reduces the number of buttons in the system and makes them more easier to use.

Voice prompts and instructions

Nowadays it’s common to see GPS units that can guide you by giving voice instructions. This is a very useful feature while driving a vehicle as it’s not safe for the driver to see the GPS display constantly.

There are two types of voice prompts.
1. The basic voice prompt technology

Provides generic instructions without referring to any names. For example ‘on the next 500 meters turn to your left’.
2. Advanced text-to-speech voice prompts

Refers the travel route using road names. Example: ‘On the next 500 meters turn left into Queens street’.

Text-to-speech voice prompts makes it easier to follow the travel routes.

Weight and Dimensions

If portability is a key requirement then you have look into the weight and dimensions of the GPS unit.

Bluetooth Integration

Bluetooth is a short range wireless technology for communication between various types of electronic devices. The devices that are interconnected via Bluetooth wireless technology creates a network known as a PAN (which stands for Personal Areas Networks).

A Bluetooth enabled GPS system can talk to a GPS enabled mobile phone. For example the user can call a hotel listed in the GPS map using a Bluetooth enabled phone and GPS system.


Capability to play mp3, wma files and dvd movies will be a nice addition to your GPS system. You get more value for your money since these entertainment features are bundled into your GPS systems.

Voice Input

Some GPS unit’s can take voice based commands. These systems are ideal for in car use since the users can operate the units without taking their hands off the steering wheel.

Data storage media and capacity

A GPS system primary needs a storage capacity to keep the electronic map. Systems that use hard drives and DVD disks can hold larger amount of map data (such the map of North America) while CD and SD card based system can only store maps of a region. Since SD cards are getting bigger in capacity and less expensive they may be able to hold more data in the future.

There are water resistant and shock proof systems in the market.

Other entertainment features

MP3 playback, audio books, picture viewers and DVD movie capability make your system more versatile. You can also save money by not buying these system separately and buying then all bundled together with you next GPS system.

Battery life

This is an important factor for portable GPS units. When you buy a battery operated unit look for one that might have support for and external power supply (example car cigarette lighter power adapter).

GPS Buyer Guide Factors

Buyer Guide

What type of GPS system is right for you?

Even though GPS systems are straight forward and easy to use devices, many people are confused in selecting the right GPS system. Choosing the right GPS Navigation System is a real challenge.

There are different types of GPS systems catering for the needs of different users and applications.

For example the GPS requirements for a hiker in the wilderness would substantially differ from the requirements of a business person who predominately uses the GPS system in busy highways.

Factors to consider

The big question that you need to ask yourself, before buying a GPS system is “What will be my primary usage of the GPS system?”
Primary Use

You need to buy a GPS system based on your primary use. The majority of our readers will find that their requirements for a GPS system would fall under one of the following categories:

1. For in car use with a any vehicle

In this class you are looking for a GPS system that can be used in car at the same time for it to be portable.

2. For in-car use in my own car

If you want to use a GPS unit primarily in your own vehicle and if your usage is very heavy, you may consider getting a GPS system permanently installed in your car. Permanently mounted GPS units are more expensive compared to the portable in-car units.

3. For in-car and pedestrian or travel use

In this class you are looking for a GPS unit that can be portable for pedestrian or travel use at the same time the system can be used in a car as well. Size and weight are important consideration in this class.

4. For hiking, mount biking and other adventure sports

These systems are ideal for sporting enthusiasts. Durability, light weight and longer battery power are key features in this class.

5. For Educational and fun activities

Ideal for beginners or students who like to use GPS for fun and learning purposes, these systems have very basic features.

How many times will you be using the GPS device per year?

* Daily
* Once a week
* Once a month
* Few times a year

If you are going to use the GPS system very heavily, it’s better to invest in a high end system.

If your usage is minimal, then you may consider investing in a mid-range system that might have other cool features such as mp3 playback and picture viewers. This way you can use the system for other purposes (example listing to songs while camping) and get more use out of the system, when it’s not being used for navigational purposes.

If you are going to use a GPS system only few times a year, invest in a basic unit.

Sometimes you may want to use a GPS only few times a year, but you may need good navigational capability. In this case try getting a laptop or PDA GPS add on module.

Price / budget

If your budget is around 100$ dollars look for a basic unit.

If your price budget is around 300$ – 500$ you can shop around for a mid range portable unit that can be used in a car as well.

If you can spend 1000$ or more go for a high end unit. Most of the high end units are in-car GPS systems.


Size, weight and battery power of the systems are key portability features. If you plan to use the system for both travel and in car purposes, go for a portable unit that comes with accessories for in-car use. If you plan to use the portable units in the wilderness make sure the system is rugged enough for your environment. Such a water resistant and shock proof/ absorbent units.